U.S. patent application number 12/692489 was filed with the patent office on 2010-11-11 for thermoelectric management unit.
Invention is credited to Jason William Dickmann, Pedro Ramon Guitart, William James Hanson, Larry Allen Larson, John Myron Rawski, Joseph David Ricke, Alan Frank Wells.
Application Number | 20100281884 12/692489 |
Document ID | / |
Family ID | 42356223 |
Filed Date | 2010-11-11 |
United States Patent
Application |
20100281884 |
Kind Code |
A1 |
Rawski; John Myron ; et
al. |
November 11, 2010 |
Thermoelectric Management Unit
Abstract
Embodiments of the invention provide a thermal management unit
including a housing, at least one fan, a plurality of
thermoelectric modules, at least one heat sink assembly coupled to
the plurality of thermoelectric modules, and controller providing
power to the plurality of thermoelectric modules. The thermal
management unit also includes a printed circuit board incorporating
the plurality of thermoelectric modules and electrically connecting
the plurality of thermoelectric modules to the controller. The
printed circuit board separates an ambient side of the thermal
management unit and an enclosure side of the thermal management
unit.
Inventors: |
Rawski; John Myron;
(Plymouth, MN) ; Larson; Larry Allen; (Rogers,
MN) ; Dickmann; Jason William; (Champlin, MN)
; Guitart; Pedro Ramon; (Lakeville, MN) ; Ricke;
Joseph David; (Arden Hills, MN) ; Hanson; William
James; (Edina, MN) ; Wells; Alan Frank;
(Anoka, MN) |
Correspondence
Address: |
GREENBERG TRAURIG (PHX)
INTELLECTUAL PROPERTY DEPARTMENT, 2450 COLORADO AVENUE , SUITE 400E
SANTA MONICA
CA
90404
US
|
Family ID: |
42356223 |
Appl. No.: |
12/692489 |
Filed: |
January 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61146593 |
Jan 22, 2009 |
|
|
|
61172266 |
Apr 24, 2009 |
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Current U.S.
Class: |
62/3.6 |
Current CPC
Class: |
H05K 7/20163 20130101;
G06F 1/206 20130101; F25B 2321/0211 20130101; F25B 21/04 20130101;
F25B 2321/0212 20130101; F25B 2321/023 20130101 |
Class at
Publication: |
62/3.6 |
International
Class: |
F25B 21/02 20060101
F25B021/02 |
Claims
1. A thermal management unit for an enclosure, the thermal
management unit comprising: a housing; at least one fan to direct
air flow through the housing; a plurality of thermoelectric
modules; at least one heat sink assembly coupled to the plurality
of thermoelectric modules; a controller providing power to the
plurality of thermoelectric modules; and a printed circuit board
incorporating the plurality of thermoelectric modules and
electrically connecting the plurality of thermoelectric modules to
the controller, the printed circuit board separating an ambient
side of the thermal management unit and an enclosure side of the
thermal management unit.
2. The thermal management unit of claim 1 wherein the plurality of
thermoelectric modules comprises a first plurality of
thermoelectric modules positioned in an area of higher air flow in
the housing and a second plurality of thermoelectric modules
position in an area of lower air flow in the housing, wherein the
controller provides higher power to the first plurality of
thermoelectric modules and lower power to the second plurality of
thermoelectric modules.
3. The thermal management unit of claim 1 wherein the controller
further provides power to the at least one fan using pulse width
modulation.
4. The thermal management unit of claim 3 wherein the controller
modulates the speed of the at least one fan in substantially
real-time.
5. The thermal management unit of claim 4 wherein the at least one
fan includes at least one enclosure fan positioned in the enclosure
side of the thermal management unit and at least one ambient fan
positioned in the ambient side of the thermal management unit,
wherein the controller individually modulates the speed of the at
least one enclosure fan and the at least one ambient fan
separately.
6. The thermal management unit of claim 1 wherein the at least one
heat sink assembly includes an ambient heat sink on the ambient
side of the thermal management unit and an enclosure heat sink on
the enclosure side of the thermal management unit.
7. The thermal management unit of claim 1 wherein the at least one
fan includes an ambient fan on the ambient side of the thermal
management unit and an enclosure air fan on the enclosure side of
the thermal management unit.
8. The thermal management unit of claim 1 wherein the controller
provides regulated voltage levels to the plurality of
thermoelectric modules.
9. The thermal management unit of claim 1 wherein the plurality of
thermoelectric modules includes one of four, eight, twelve, and
sixteen thermoelectric modules.
10. The thermal management unit of claim 1 wherein the ambient side
of the thermal management unit and the enclosure side of the
thermal management unit are positioned inside the enclosure, and
the ambient side is in communication with air outside the
enclosure.
11. The thermal management unit of claim 1 wherein the ambient side
of the thermal management unit is positioned outside of the
enclosure and the enclosure side of the thermal management unit is
positioned inside of the enclosure.
12. The thermal management unit of claim 1 wherein the ambient side
of the thermal management unit and the enclosure side of the
thermal management unit are positioned outside the enclosure, and
the enclosure side is in communication with air inside the
enclosure.
13. The thermal management unit of claim 1 further comprising a
thermal transfer material applied at an interface between the
plurality of thermoelectric modules and the at least one heat sink
assembly.
14. The thermal management unit of claim 1 further comprising a
tachometer to measure a speed of the at least one fan, the
tachometer being in communication with the controller.
15. The thermal management unit of claim 1 wherein the printed
circuit board includes electrical connections to at least
electrically connect the controller to the plurality of
thermoelectric modules, the electrical connections being positioned
on the enclosure side of the thermal management unit.
16. The thermal management unit of claim 1 further comprising at
least one temperature sensor in communication with the
controller.
17. The thermal management unit of claim 16 wherein the at least
one temperature sensor is a thermistor and is positioned to monitor
temperature of the air flow through the housing.
18. The thermal management unit of claim 17 wherein the at least
one temperature sensor is positioned along at least one of an inlet
of the ambient side of the thermal management unit, an outlet of
the ambient side of the thermal management unit, an inlet of the
enclosure side of the thermal management unit, and an outlet of the
enclosure side of the thermal management unit.
19. The thermal management unit of claim 1 wherein the controller
is adapted to change a polarity of the power to the plurality of
thermoelectric modules.
20. The thermal management unit of claim 1 further comprising an
alarm in communication with the controller, the alarm being
activated by the controller when the controller senses a fault in
the thermal management unit.
21. The thermal management unit of claim 20 wherein the alarm
includes at least one of a visual alarm and an audio alarm.
22. The thermal management unit of claim 1 further comprising an
external communication link connected to the controller.
23. The thermal management unit of claim 1 further comprising one
of an RS-232 port, an I2C communications port, an RS-485 port, a
USB port, and an ETHERNET port connected to the controller
24. A thermal management unit for an enclosure, the thermal
management unit comprising: a housing; at least one fan to direct
air flow through the housing; a first plurality of thermoelectric
modules positioned in an area of higher air flow in the housing; a
second plurality of thermoelectric modules position in an area of
lower air flow in the housing; a first heat sink assembly coupled
to the first plurality of thermoelectric modules; a second heat
sink assembly coupled to the second plurality of thermoelectric
modules; and a controller providing power to the first plurality of
thermoelectric modules and the second plurality of thermoelectric
modules, the controller providing a higher power to the first
plurality of thermoelectric modules and a lower power to the second
plurality of thermoelectric modules.
25. The thermal management unit of claim 24 further comprising a
printed circuit board incorporating the first plurality of
thermoelectric modules and the second plurality of thermoelectric
modules, the printed circuit board electrically connecting the
first plurality of thermoelectric modules and the second plurality
of thermoelectric modules to the controller, the printed circuit
board separating an ambient side of the thermal management unit and
an enclosure side of the thermal management unit.
26. A thermal management unit for an enclosure, the thermal
management unit comprising: a housing; at least one fan to direct
air flow through the housing; a plurality of thermoelectric
modules; at least one heat sink assembly coupled to the plurality
of thermoelectric modules; a controller providing regulated power
independently to at least one of the plurality of thermoelectric
modules to optimize thermal management unit performance; and a
printed circuit board incorporating the plurality of thermoelectric
modules and electrically connecting the plurality of thermoelectric
modules to the controller, the printed circuit board separating an
ambient side of the thermal management unit and an enclosure side
of the thermal management unit.
27. A thermal management unit for an enclosure, the thermal
management unit comprising: a housing; at least one fan to direct
air flow through the housing; a plurality of thermoelectric
modules; at least one heat sink assembly coupled to the plurality
of thermoelectric modules; a controller providing power
independently to at least one of the at least one fan to vary
airflow to the plurality of thermoelectric modules and the at least
one heat sink assembly to optimize thermal management unit
performance; and a printed circuit board incorporating the
plurality of thermoelectric modules and electrically connecting the
plurality of thermoelectric modules to the controller, the printed
circuit board separating an ambient side of the thermal management
unit and an enclosure side of the thermal management unit.
Description
RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.119
to U.S. Provisional Patent Application Nos. 61/146,593, filed on
Jan. 22, 2009 and 61/172,266, filed on Apr. 24, 2009, the entire
contents of which are incorporated herein by reference.
BACKGROUND
[0002] Thermal management units, such as air conditioning and
heating units, are used to cool and heat electrical enclosures.
Most conventional thermal management units use compressors.
However, thermoelectric (TE) devices can convert electrical current
into heating or cooling based on the Peltier effect and are
generally much more efficient than compressors.
[0003] Electrical circuits that provide electrical current to the
TE devices are often housed in junction boxes separate from the
thermal management units. These junction boxes are bulky and take
up an excessive amount of space within the electrical
enclosures.
SUMMARY
[0004] Some embodiments of the invention provide a thermal
management unit for an enclosure. The thermal management unit
includes a housing, at least one fan to direct air flow through the
housing, a plurality of thermoelectric modules, at least one heat
sink assembly coupled to the plurality of thermoelectric modules,
and controller providing power to the plurality of thermoelectric
modules. The thermal management unit also includes a printed
circuit board incorporating the plurality of thermoelectric modules
and electrically connecting the plurality of thermoelectric modules
to the controller. The printed circuit board separates an ambient
side of the thermal management unit and an enclosure side of the
thermal management unit. The plurality of thermoelectric modules
can include a first plurality of thermoelectric modules positioned
in an area of higher air flow in the housing and a second plurality
of thermoelectric modules position in an area of lower air flow in
the housing. The controller can provide higher power to the first
plurality of thermoelectric modules and lower power to the second
plurality of thermoelectric modules.
DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1A is a perspective view of an ambient side of a
thermoelectric (TE) management unit according to one embodiment of
the invention.
[0006] FIG. 1B is a perspective view of an enclosure side of the TE
management unit of FIG. 1A.
[0007] FIGS. 2A-2D are top, front, side, and back views of a TE
management unit according to one embodiment of the invention.
[0008] FIG. 3 is a perspective view of a heat sink assembly
including a TE module, an enclosure heat sink, and an ambient heat
sink for use in the TE management unit of FIGS. 1A and 1B.
[0009] FIGS. 4A-4E are perspective and various side views of the
heat sink assembly of FIG. 3.
[0010] FIGS. 5A-5F are perspective and various views of alternate
head sinks for use with the TE management unit.
[0011] FIGS. 6A-6B are tables of performance values for a phase
change material (PCM) for use in the interface between the TE
module and the heat sinks of FIG. 3.
[0012] FIGS. 7A, 7B, and 7C are side views of a TE management unit
positioned half inside and half outside an enclosure, outside an
enclosure, and inside an enclosure, respectively.
[0013] FIGS. 8A-8D are block wiring diagrams of electrical
configurations of TE modules in a thermoelectric management unit
according to some embodiments of the invention.
[0014] FIG. 9 is a block diagram of a controller for use with a TE
management unit according to one embodiment of the invention.
[0015] FIGS. 10A-10J are a block diagram and electrical schematics
of a control circuit of the controller of FIG. 9.
[0016] FIGS. 11A-11E are a block diagram and electrical schematics
of a power circuit of the controller of FIG. 9.
[0017] FIG. 12 is a wiring schematic of components of the TE
management unit.
[0018] FIG. 13 is a top view of a printed circuit board for use
with the TE management unit according to one embodiment of the
invention.
[0019] FIGS. 14A-14G are flow charts of a control scheme according
to one embodiment of the invention for use with the TE management
unit.
[0020] FIG. 15A is a perspective view of an ambient side of a TE
management unit according to another embodiment of the
invention.
[0021] FIG. 15B is a perspective view of an enclosure side of the
TE management unit of FIG. 15A.
[0022] FIG. 16 is a perspective view of a separator printed circuit
board including a plurality of heat sink assemblies for use with
the TE management unit of FIGS. 15A-15B.
[0023] FIG. 17 is a front view of an enclosure side of the
separator printed circuit board of FIG. 16.
[0024] FIG. 18 is a front view of an ambient side of the separator
printed circuit board of FIG. 16.
[0025] FIGS. 19A-19H are a block diagram and electrical schematics
of a power circuit according to another embodiment of the invention
for use with a TE management unit.
[0026] FIGS. 20A-20I are a block diagram and electrical schematics
of a control circuit according to another embodiment of the
invention for use with a TE management unit.
DETAILED DESCRIPTION
[0027] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless specified or limited otherwise,
the terms "mounted," "connected," "supported," and "coupled" and
variations thereof are used broadly and encompass both direct and
indirect mountings, connections, supports, and couplings. Further,
"connected" and "coupled" are not restricted to physical or
mechanical connections or couplings.
[0028] The following discussion is presented to enable a person
skilled in the art to make and use embodiments of the invention.
Various modifications to the illustrated embodiments will be
readily apparent to those skilled in the art, and the generic
principles herein can be applied to other embodiments and
applications without departing from embodiments of the invention.
Thus, embodiments of the invention are not intended to be limited
to embodiments shown, but are to be accorded the widest scope
consistent with the principles and features disclosed herein. The
following detailed description is to be read with reference to the
figures, in which like elements in different figures have like
reference numerals. The figures, which are not necessarily to
scale, depict selected embodiments and are not intended to limit
the scope of embodiments of the invention. Skilled artisans will
recognize the examples provided herein have many useful
alternatives and fall within the scope of embodiments of the
invention.
[0029] FIGS. 1A and 18 illustrate a thermoelectric (TE) management
unit 10 according to one embodiment of the invention. The TE
management unit 10 can be used to cool and/or heat an electrical
enclosure 12 (as shown schematically in FIGS. 7A-7C) or other
enclosed space. As shown in FIGS. 2A-2D, the TE management unit 10
can include a housing 14 with an enclosure (e.g., internal) side 16
and an ambient (e.g., external) side 18. The enclosure side 16 can
be used to condition air in the enclosure 12. If the TE management
unit 10 is being used to cool the enclosure 12, the enclosure side
16 and the ambient side 18 can be considered a cold side and a warm
side, respectively. If the TE management unit 10 is being used to
warm the enclosure 12, the enclosure side 16 and the ambient side
18 can be considered a warm side and a cold side, respectively. In
addition, the enclosure side 16 can include an enclosure air inlet
11 (as shown in FIG. 2C) and an enclosure air outlet 13 and the
ambient side can include an ambient air inlet 15 (as shown in FIG.
2B) and an ambient air outlet 17 (as shown in FIG. 2D). In some
embodiments, the housing 14 can be a NEMA type 12, 3R, 4, or 4X
housing constructed of stainless steel. In one embodiment, the
housing 14 can be coated with a light grey (e.g., RAL 7035)
semi-texture paint.
[0030] As shown in FIG. 1A, the TE management unit 10 can include
one or more heat sink assemblies 20. The number of heat sink
assemblies 20 can depend on the necessary cooling or heating
capacity of the TE management unit 10. As shown in FIGS. 3 and
4A-4E, each heat sink assembly 20 can include an ambient heat sink
22 and an enclosure heat sink 24. In some embodiments, the
enclosure heat sink 24 can be smaller than the ambient heat sink
22. The ambient heat sink 22 can be coupled to the enclosure heat
sink 24 with fasteners 25, such as bolts and washers, or attached
in another suitable manner. One suitable type of heat sink that can
be used for the ambient heat sink 22 and/or the enclosure heat sink
24, as shown in FIGS. 5A-5F, is sold by AAVID Thermalloy.
[0031] As shown in FIG. 3, each heat sink assembly 20 can include a
TE module 26 positioned between the ambient heat sink 22 and the
enclosure heat sink 24. The TE module 26 can include two wires 28,
30. When a voltage is applied to the wires 28, 30, the TE module 26
can transfer heat from one side of the TE management unit 10 (e.g.,
the ambient side 18) to the other side of the TE management unit 10
(e.g., the enclosure side 16). Due to the TE management unit 10
using the TE modules 26 rather than a compressor, as used in
conventional thermal management units, the TE management unit 10
can be easier to manufacture and also easier to service after
installation. In addition, the TE management unit 10 can be
substantially quieter compared to conventional units that use
compressors. The TE management unit 10 can also be used for
condensate management in the enclosure 12.
[0032] In one embodiment as shown in FIGS. 1A and 1B, the TE
management unit 10 includes twelve separate heat sink assemblies 20
coupled to a panel 32. The panel 32 can include twelve apertures
through which the heat sink assemblies 20 can be positioned.
Depending on the thermal (i.e., cooling or heating) capacity
necessary for a particular application, the TE management unit 10
can include any suitable number of heat sink assemblies 20. In some
embodiments, the thermal capacity of the TE management unit 10 can
range from about 100 watts to about 1000 watts. Table 1 below lists
approximate cooling capacities and approximate unit sizes for TE
management units 10 according to some embodiments of the
invention.
TABLE-US-00001 TABLE 1 Nominal Cooling Capacity and Nominal Unit
Size Nominal Cooling Nominal Unit Size Capacity (height .times.
width .times. depth) 100 Watts 5.5'' .times. 12'' .times. 6'' 200
Watts 5.5'' .times. 12'' .times. 6'' 300 Watts 7.0'' .times. 15.5''
.times. 8'' 400 Watts 9.0'' .times. 17.5'' .times. 8'' 600 Watts
9.0'' .times. 17.5'' .times. 8'' 800 Watts 9.0'' .times. 17.5''
.times. 8'' 1000 Watts 11.0'' .times. 23.5'' .times. 10''
[0033] The TE management unit 10 can include one or more ambient
fans 34 coupled to the panel 32 (which are illustrated as fan
housings in FIG. 1A). As shown in FIGS. 1A and 2C, the ambient fans
34 can move air from the ambient inlet 15, across the ambient heat
sinks 22, and out the ambient outlet 17, away from the TE
management unit 10, creating an ambient air loop. As shown in FIG.
1B, the TE management unit 10 can also include one or more
enclosure fans 36. As shown in FIGS. 1B and 2C, the enclosure fans
36 can move air from the enclosure inlet 11, across the enclosure
heat sinks 24, and out the enclosure outlet 13 to feed conditioned
air back into the enclosure 12, creating an enclosure air loop. In
some embodiments, the ambient fans 34 and/or the enclosure fans 36
can be impeller fans.
[0034] The heat sink assemblies 20 can be designed in a modular
fashion so that any suitable number of heat sink assemblies 20 can
be used to achieve the desired thermal capacity. The modular heat
sink assemblies 20 can also minimize the effects of shear forces
that occur in the TE modules 26, as compared to conventional,
larger heat sink assemblies that are coupled to multiple TE
modules. Since the colder side of the TE module 26 will contract in
size and the warmer side of the TE module 26 will expand in size,
large heat sinks attached to multiple TE modules tend to experience
shear stresses, warping, and the loss of physical contact, and
thus, the loss of efficient thermal transfer with some of the TE
modules. Also, when large heat sinks warp, gaskets between the heat
sink and the enclosure can start to leak, allowing water from
outdoors to leak inside the enclosure.
[0035] Using the modular heat sink assemblies 20 can help minimize
the effects of shear stresses and warping at the interface between
the TE modules 26 and the heat sinks 22, 24. A phase change
material (PCM), or other suitable thermal transfer material, can
also be used at the interface between the TE modules 26 and the
heat sinks 22, 24. The PCM can enhance thermal transfer. Once
suitable PCM is sold by Berquist under the brand Hi-Flow.RTM. 225U,
as described in the tables of FIGS. 6A-6B.
[0036] The housing 14 can be a side-mount type unit and can be
rack-mounted to the enclosure 12. In other embodiments, the housing
14 can be mounted to the enclosure 12 via other suitable mounting
methods. FIG. 7A illustrates the TE management unit 10 with the
ambient side 18 positioned outside of the enclosure 12 and the
enclosure side 16 positioned inside the enclosure 12 (i.e., a
partial recess unit). FIG. 7B illustrates both the ambient side 18
and the enclosure side 16 positioned outside the enclosure 12
(i.e., a full exterior unit), with the enclosure air inlet 11 and
enclosure air outlet 13 positioned so that the enclosure fans 36
can pull air from the enclosure 12 through the enclosure air loop.
FIG. 7C illustrates both the ambient side 18 and the enclosure side
16 positioned inside the enclosure 12 (i.e., a full recess unit),
with the ambient air inlet 15 and ambient air outlet 17 positioned
so that the ambient fans 34 can pull air from outside the enclosure
12 through the ambient air loop.
[0037] In some embodiments, the modular design concept is based on
using the single panel 32 that incorporates the TE modules 26. The
TE modules 26 can be ganged together in order to provide the TE
management unit 10 with increased thermal capacity. More
specifically, each TE module 26 configuration can have a wiring
scheme that allows the TE management unit 10 to achieve a maximum
combination of efficiency and thermal power. FIGS. 8A-8B illustrate
wiring options for TE module sets with sixteen TE modules 26. In a
configuration with sixteen TE modules 26, the air distribution may
not even be across all sixteen TE modules 26, and there may be
areas of higher flow and areas of lower flow. The sixteen TE module
stack can be configured as two, three, or four separate strings to
allow a control system to achieve maximum benefits of thermal power
and efficiency by providing more or less power to each string. The
TE management unit 10 can include lower power TE modules 26 in an
area of lower air flow and higher power TE modules 26 in an area of
higher air low. In this manner, each TE module 26 can achieve a
higher level of efficiency, with the net result a higher efficiency
of the entire thermal unit. For a three-string configuration, since
sixteen TE modules cannot be evenly divided by three, multiple
uneven strings can be used (e.g., two strings of five TE modules 26
and one string of six TE modules 26). FIGS. 8C-8D illustrate wiring
options for TE module sets with twelve and eight TE modules 26,
respectively.
[0038] Fan power has a large effect on efficiency of the TE
management unit 10, and fan speed has a large affect on fan power.
The fans 34, 36, as well as the TE modules 26, can be monitored and
controlled to achieve maximum efficiency at all combinations of
temperatures. In some embodiments of the invention, the speed of
the fans 34, 36 can be varied (e.g., in substantially real-time)
based on a combination of inputs to a controller 38 to maximize
efficiency given a particular thermal load. The thermal transfer,
or thermal load, can be determined by measuring a temperature
difference across the TE modules 26. The controller 38 can
incorporate this information into a programmed algorithm to set the
optimum fan speed for each combination of power input, cooling
output, ambient temperature, and enclosure temperature. Fan speed
can be controlled using pulse width modulation (PWM) control with a
tachometer output to monitor status and, in some embodiments, the
ambient fans 34 can be controlled separately from the enclosure
fans 36. In addition, power to the TE modules 26 can be controlled
to vary the thermal transfer of the TE management unit 10.
[0039] In some embodiments, the approach to variable control can be
to adjust the TE module power based on the thermal load required.
Normal fan control options for this approach can be as follows: (1)
let both the enclosure and ambient fans run full speed; (2) let the
enclosure fan run full speed and speed control the ambient fans
based on external air in temperature or air out temperature; (3)
let the external fan run full speed and speed control the ambient
fan based on a temperature difference that is set at a fixed value;
and (4) speed control both the enclosure and ambient fans, as
described in the previous paragraph. The control of the fans 34, 36
and the TE modules 26 according to some embodiments of the
invention is further described below with respect to the flowcharts
of FIGS. 13A-13G.
[0040] FIG. 9 illustrates the controller 38 according to one
embodiment of the invention. The controller 38 can include a
control circuit 39, as shown in FIGS. 10A-10J, and a power circuit
41, as shown in FIGS. 11A-11E. The electrical circuits of FIGS.
10A-10J and 11A-11E can be incorporated into a separate junction
box or control board that is positioned remotely from the TE
management unit 10. In one embodiment, the control circuit 39 can
be housed in one junction box and the power circuit 41 can be
housed in another, separate junction box.
[0041] As shown in FIG. 10A, the control circuit 39 can include a
temperature sensor circuit 40 (further illustrated in FIG. 10B), a
fan speed control circuit 42 (further illustrated in FIG. 10C), a
tachometer circuit 44 (further illustrated in FIG. 10D), an alarms
circuit 46 (further illustrated in FIG. 10E), a serial port 48
(further illustrated in FIG. 10F), a memory/external interface
circuit 50 (further illustrated in FIG. 10G), a programming
interface 52 (further illustrated in FIG. 10H), a power monitor
circuit 54 (further illustrated in FIG. 10I), and a microcontroller
circuit 56 (further illustrated in FIG. 10J). In one embodiment,
these components can be connected as shown by the connections in
FIG. 10A as described below.
[0042] FIG. 10B illustrates the temperature sensor circuit 40 of
the control circuit 39. The temperature sensor circuit 40 can
include four temperature sensors S1-S4. The temperature sensors
S1-S4 can be thermistors (e.g., 10 kilo-ohm thermistors with a 1%
tolerance), thermocouples, or similar devices. Each temperature
sensor S1-S4 can have an accompanying sensor circuit including
three resistors and one capacitor: Resistors R1-R3 and capacitor C1
for sensor S1; resistors R4-R6 and capacitor C2 for sensor S2;
resistors R7-R9 and capacitor C3 for sensor S3; and resistors
R10-R12 and capacitor C4 for sensor S4. In some embodiments,
resistors R1, R4, R7, and R10 can be about 232 kilo-ohms with a 1%
tolerance, resistors R2, R5, R8, and R11 can be about 1 kilo-ohm
with a 1% or 5% tolerance, and resistors R3, R6, R9, and R12 can be
about 10 kilo-ohms with a 1% or 5% tolerance. In addition,
capacitors C1-C4 can have a capacitance of about 0.1 microfarads.
Resistors R1-R12, as well as all other resistors described herein,
can be provided using incorporated resistor packs, such as DIP
(dual in-line) packages. Each accompanying sensor circuit can also
include an input voltage V1. In one embodiment, the voltage V1 is
about 3.3 volts.
[0043] The first sensor circuit, including sensor S1, can be routed
to the microcontroller circuit 56 via a connection 58. The second
sensor circuit, including sensor S2, can be routed to the
microcontroller circuit 56 via a connection 60. The third sensor
circuit, including sensor S3, can be routed to the microcontroller
circuit 56 via a connection 62. Finally, the fourth sensor circuit,
including sensor S4, can be routed to the microcontroller circuit
56 via a connection 64.
[0044] The temperature sensors S1-S4 can be remotely mounted in
various airflow regions (e.g., of the housing 14) for temperature
control. For example, one of the temperature sensors (S1, for
example) can be positioned at the enclosure inlet 11 and another
temperature sensor (S2, for example) can be positioned at the
enclosure outlet 13. A third temperature sensor (S3, for example)
can be positioned at the ambient inlet 15 and a fourth temperature
sensor (S4, for example) can be positioned at the ambient outlet
17. Therefore, temperatures can be sensed at both the inlets and
outlets of the enclosure air loop and the ambient air loop. In some
embodiments, the temperature sensors S1-S4 can have a temperature
accuracy of about +/-2 degrees Celsius. In addition, in some
embodiments, the controller 38 can have an operational temperature
range of about minus 40 degrees Celsius to about 80 degrees
Celsius.
[0045] FIG. 10C illustrates the fan speed control circuit 42 of the
control circuit 39. The fan speed control circuit 42 can operate
servomotors for each fan 34, 36. In some embodiments, PWM speed
control can be used to operate the servomotors (i.e., via the fan
speed control circuit 42), and open collector tachometers can be
used for feedback (i.e., via the tachometer circuit 44, described
with respect to FIG. 10D), allowing full closed-loop digital
control for the fans 34, 36. The fan speed control circuit 42 can
connect to PWM inputs for each fan. For example, a connection 66
can lead to a PWM input for a first ambient fan 34, a connection 68
can lead to a PWM input for a second ambient fan 34, a connection
70 can lead to a PWM input for a first enclosure fan 36, and a
connection 72 can lead to a PWM input for a second enclosure fan
36.
[0046] As shown in FIG. 10C, the controller 38 can independently
speed control each of the four fans 34, 36 separately. To speed
control the first ambient fan 34 (via the connection 66), a PWM
signal from the microcontroller circuit 56 is transmitted to a
resistor R13 via a connection 74 and can switch on and off a
transistor Q1. The base of the transistor Q1 can be connected to
the resistor R13 and the emitter of the transistor Q1 can be
connected to ground. When the signal from connection 74 applies a
substantial cut-in voltage across the base-emitter junction, the
transistor Q1 becomes active and allows current flow from the
collector to the emitter. The current is conducted from a voltage
source V2 (e.g., about 15 volts), through resistors R14 and R15,
and through the collector and the emitter to ground. The connection
66 is connected between the resistors R14 and R15 to provide the
PWM input to the first ambient fan 34 when the transistor Q1 is on.
This method is used to speed control the second ambient fan 34, and
the first and second enclosure fans 36 as well, via PWM inputs to
connections 76, 78, and 80, respectively, from the microcontroller
circuit 56. The resistor R13, and resistors R16, R19, and R22, can
be about 100 ohms. The resistor R14, and resistors R17, R20, and
R23, can be about 100 kilo-ohms. The resistor R15, and resistors
R18, R21, and R24, can be about 100 ohms. The transistor Q1, and
transistors Q2, Q3, and Q4, can be NPN, BJT transistors, such as
Part No. 2N222, manufactured by Fairchild Semiconductors.RTM.,
among others.
[0047] The fans 34, 36 can be modulated from minimum to maximum
control points. For example, the enclosure fans 36 can be operated
between 75% and 100% of their maximum speed and the ambient fans 34
can be operated between 25% and 100% of their maximum speed. In one
embodiment, the maximum speed for both the enclosure fans 36 and
the ambient fans 34 can be about 4900 rotations per minute (RPM).
In another embodiment, the enclosure fans 36 can operate at or
above about 3000 RPM and the ambient fans 34 can operate at or
above about 1000 RPM. In some embodiments, the fans 34, 36 can be
digitally stable up to 4 kilo-Hertz control frequency.
[0048] FIG. 10D illustrates the tachometer circuit 44 of the
control circuit 39. The tachometer circuit 44 can receive outputs
from open collector tachometers (not shown) in connection with the
fans 34, 36 to monitor fan speed. The controller 38 can use the
outputs from the tachometer circuit 44 to adjust the PWM inputs to
the fans 34, 36, if necessary. The tachometer circuit 44 can
convert the tachometer outputs (in pulses per revolution) to
frequencies in hertz to analyze the fan speeds (e.g., using a timer
to determine a period between rising edges of the tachometer
outputs). A calculated tachometer frequency in hertz can be equal
to one to six pulses per revolution, depending on a gain value
used. For example, in one embodiment, the tachometer frequency from
the ambient fans 34 can be equal to four pulses per revolution
(i.e., the gain value is four), while the tachometer frequency from
the enclosure fans 36 can be equal to one pulse per revolution
(i.e., the gain value is one). The tachometer outputs can be
referenced to a power return line of the fans 34, 36.
[0049] As shown in FIG. 10D, a connection 82 can be connected to a
tachometer output of the first ambient fan 34, a connection 84 can
be connected to a tachometer output of the second ambient fan 34, a
connection 86 can be connected to a tachometer output of the first
enclosure fan 36, and a connection 88 can be connected to a
tachometer output of the second enclosure fan 36. Each tachometer
output connection 82, 84, 86, 88 can have an accompanying circuit
including two resistors and one capacitor leading to a multiplexer
U1: Resistors R25-R26 and capacitor C5 for the connection 82,
leading to pin 4 of the multiplexer U1; resistors R27-R28 and
capacitor C6 for the connection 84, leading to pin 3 of the
multiplexer U1; resistors R29-R30 and capacitor C7 for the
connection 86, leading to pin 2 of the multiplexer U1; and
resistors R31-R32 and capacitor C8 for the connection 88, leading
to pin 1 of the multiplexer U1. The resistors, R25, R27, R29, and
R31 can each be about 100 kilo-ohms. The resistors R26, R28, R30,
and R32 can each be about 1 kilo-ohms. The capacitors C5-C8 can be
about 0.01 microfarads.
[0050] The multiplexer U1 can be an 8-input multiplexer, such as
Part No. 74HC151, manufactured by Philips Semiconductors. Pins 1-4,
which can be coupled to connections 82, 84, 86, and 88 can be
multiplexer inputs of the multiplexer U1. Pins 12-14 can also be
multiplexer inputs and can receive outputs from various override
devices, such as smoke detectors, door switches, etc., which the
control circuit 39 can monitor. In FIG. 10D, pins 14 and 15 are
connected to override devices (not shown), while pins 12 and 13 are
left open. For example, an input signal from the override device at
a connection 90 is transmitted through a resistor R33 to a
regulator U2 (i.e., a voltage regulator) and a return connection to
the override device can be at a connection 92. A positive output
from the regulator U2 creates a voltage at resistor R34 from
voltage V1, sending a positive voltage to pin 15 of the multiplexer
U1. A similar circuit for pin 14 of the multiplexer U1 can include
an input connection 94, a return connection 96, resistors R35-R36,
and a regulator U3. The resistors R34 and R36 can each be about 100
kilo-ohms. In some embodiments, the resistors R33 and R35 can
depend on the override device to which they are connected. In one
example, the resistors R33 and R35 can be about 1 kilo-ohm and
about 100 ohms, respectively.
[0051] The multiplexer U1 also receives an enable input at pin 7
from the microcontroller circuit 56 via a connection 98. In
addition, select inputs to pins 9, 10, and 11 of the multiplexer U1
are routed from the microcontroller circuit 56 via connections 100,
102, and 104, respectively. The output of the multiplexer, at pin
5, is routed to the microcontroller circuit 56 via a connection
106. The select inputs (connections 100, 102, and 104 from the
microcontroller circuit 56) can also be routed to the alarm circuit
46, as shown in FIG. 10E.
[0052] FIG. 10E illustrates the alarm circuit 46 of the control
circuit 39. The alarm circuit 46 can include four independent,
optically-isolated, open-collector outputs for remote alarm output
detection. For example, a first alarm (not shown) can be connected
via an input connection 108 and a return connection 110, a second
alarm (not shown) can be connected via an input connection 112 and
a return connection 114, a third alarm (not shown) can be connected
via an input connection 116 and a return connection 118, and a
fourth alarm (not shown) can be connected via an input connection
120 and a return connection 122. Alarm outputs can be controlled
via a latch U4. As shown in FIG. 10E, the input connection to each
alarm is connected to the latch U4 via a resistor, a regulator, and
another resistor, and the return connection for each alarm is
connection through the regulator to ground. Thus, the first alarm
is connected to the latch U4 at pin 4 via resistors R37 and R38 and
a regulator U5, the second alarm is connected to the latch U4 at
pin 5 via resistors R39 and R40 and a regulator U6, the third alarm
is connected to the latch U4 at pin 6 via resistors R41 and R42 and
a regulator U7, and the fourth alarm is connected to the latch U4
at pin 7 via resistors R43 and R44 and a regulator U8. If the latch
U4 outputs a high logic level at any of pins 4-7, the respective
alarm will be activated, indicating a fault in the TE management
unit 10. If the latch U4 outputs a low logic level, there is no
fault and the alarm is not activated. In some embodiments,
resistors R38, R40, R42, and R44 can each be about 330 ohms,
resistors R37 and R39 can each be about 100 ohms, and resistors R41
and R43 can each be about 1 kilo-ohm.
[0053] The latch U4 can also provide output signals to remote
devices, such as slave units. For example, pins 9 and 10 can be
connected to remote units via connections 124 and 126, through
resistors R45 and R46, respectively. Both resistors R45 and R46 can
have a resistance of about 330 ohms. The remote units can also be
connected to a reference voltage V1 via a connection 128, and
ground via a connection 130. The latch U4 can also output signals
to alarm light emitting diodes (LEDs) via pins 11 and 12. For
example, two LEDS, D1 and D2, can be used to communicate alarm
outputs. In one embodiment, D1 is a green LED and D2 is a red LED.
If an alarm function is active (i.e., if a fault has occurred), D1
can be switched off and D2 can be switched on. If the alarm
function is not active, the D1 can be switched on and D2 can be
switched be off. The LEDs D1 and D2 can be connected to pins 11 and
12 through resistors R47 (about 100 ohms) and R48 (about 100
kilo-ohms), respectively.
[0054] The latch U4 can be an 8-bit addressable latch, such as part
no. 74HC259, manufactured by Philips Semiconductors. Address inputs
to pins 1, 2, and 3 can be from the connections 104, 102, and 100,
respectively, from the microctroller circuit 40 (the connections
104, 102, and 100 are also routed to the tachometer circuit 44). An
enable input to pin 14 of the latch U4 can be received from the
microcontroller circuit 56 via a connection 132. Pin 15 can be a
conditional reset input, which is active when low, and can be
connected to the voltage V1. Pin 13 can receive input data from the
microcontroller circuit 56 via a connection 134.
[0055] Various faults can activate alarm outputs for the alarms.
Faults that can activate the first, second, and third alarms, in
some embodiments, are described below.
[0056] The first alarm output can be an airflow alarm, caused by
failing fans (e.g., a fan fault) or an excessive temperature change
across the enclosure or ambient airflow loops (e.g., a temperature
delta fault). Ambient or enclosure temperature delta faults can
occur when a measured temperature across the TE module 26 is
greater than about 15 degrees Celsius. If this occurs, the
controller 38 can, in addition to activating the first alarm
output, reset the TE power to about zero and ramp the power back up
to a steady state value. If there is an enclosure temperature delta
fault, the controller 38 can also run the enclosure fans 36 at
maximum speed. Similarly, if there is an ambient temperature delta
fault, the controller 38 can also run the ambient fans 34 at
maximum speed. Additionally, if any fan 34, 36 fails, the
controller 38 can run all other functioning fans 34, 36 at maximum
speed.
[0057] The second alarm output can be a temperature or sensor
failure alarm, due to a failing sensor (e.g., a sensor fault) or an
exceeded enclosure high or low temperature limit as measured by the
enclosure inlet temperature sensor S1 (e.g., a temperature fault).
For example, a high temperature alarm can be activated when a
temperature sensor (the enclosure inlet temperature sensor S1, for
example), is about 10 degrees Celsius above the cooling set-point
and a low temperature alarm can be activated when the temperature
sensor (also the temperature sensor S1, for example) is about 10
degrees Celsius below the heating set-point. Plus or minus about 10
degrees Celsius can be a factory default for the high and low
temperature limits and can be adjusted by a user. A sensor fault
can occur, and the second alarm can be activated, if any
temperature sensor S1-S4 reads less than about minus 50 degrees
Celsius or greater than about 85 degrees Celsius. If either of
these conditions is measured, it can be assumed that the
temperature sensor in question (i.e., S1, S2, S3, or S4) has failed
and, in addition to the second alarm, the controller 38 can set the
TE voltage to about 18 volts, direct current (Vdc) and set the fans
34, 36 to maximum speed.
[0058] A third alarm output can be a power fault alarm, which can
be triggered by power faults (e.g., if the controller input voltage
is out of range, the fan voltage or current is out of range, or if
the TE module voltage or current is out of range). For example, a
power fault can be triggered if the TE current (i.e., the current
to the TE modules 26) is greater than about 20 amperes, direct
current, or the voltage is greater than about 24 Vdc. If such an
event occurs, the controller 38 can reset the TE module power to
zero and ramp the power back up to a steady state value, and run
the fans 34, 36 at maximum speed. In another example, a power fault
can be triggered if the fan current (i.e., the current to the fans
34, 36) is greater than about 4 amperes, direct current. If such an
event occurs, the controller 38 can reset the fan power to zero and
ramp the voltage back up to about 12 Vdc.
[0059] The controller 38 can have a delay period (e.g., thirty
seconds or fifteen seconds) for alarm outputs to minimize nuisance
alarms. Any of the alarms can be on and stable for the full delay
period to activate the output and display functions when the delay
period has been exceeded. For any faults, the controller 38 can
either continue normal operation, or go to a max ON condition
(e.g., by setting the TE module voltage to about 18 Vdc and the
fans 34, 36 to maximum speed). In some embodiments, alarm pull-ups
can be provided to reset the alarms. The pull-ups can be referenced
to the return connections of the alarms (e.g., the connections 110,
114, 118, and 122) and can have maximum parameters of about 5
milli-amperes and about 80 Vdc.
[0060] FIG. 10F illustrates the serial port 48 of the control
circuit 39. The serial port 48 can be an external communication
link for the microcontroller circuit 56 to communicate with an
outside source (e.g., an external computer) for automated test
functions, data logging, etc. In one embodiment, the serial port 48
can allow RS-232 communication between the microcontroller circuit
56 and the outside source. The serial port 48 can receive signals
from the microcontroller circuit 56 via a connection 136 and can
transmit signals to the microcontroller circuit 56 via a connection
138. The serial port 48 can also have a power connection, using the
voltage V1, and a ground connection. The outside source can command
the controller 38 via the serial port 48 to run in a manual mode
and begin automated testing. The outside source can further command
the controller 38 back into normal mode to continue normal
operation after, or during, testing. For example, the outside
source can manually override control temperatures to force the TE
management unit 10 to run in a certain test state. The outside
source can send a request to receive all controller data during or
after the test. Data from past operations can be collected and/or
data can be collected in near real-time. The data can be processed
by the outside source to determine the results of the test. If,
while connected to the outside source and a command is not received
for a time period, such as 15 seconds, the controller 38 can revert
back to normal mode. In some embodiments, the serial port 48 can be
an "I2C" communications port, an RS-232 port, an RS-485 port, a USB
port, or an Ethernet port.
[0061] FIG. 10G illustrates the memory/external interface circuit
50 of the control circuit 39. The memory/external interface circuit
50 can include a memory chip U9 and connection port J1. The memory
chip U9 can be a SEEPROM (serial EEPROM) chip. The connection port
J1 can be used to connect an external device, such as a display
board. "I2C" communications can be used for communication between
the microcontroller circuit 56, the memory chip U9, and the
connection port J1 via connections 140 and 142. For example, I2C
communications can be used with the memory chip U9 for loading and
storing controller runtime variables and logging faults. In some
embodiments, the connection 140 can be a data line and the
connection 142 can be a clock line. Also, resistors R49 and R50,
both about 1 kilo-ohm, can be included in the memory/external
interface circuit 50, connecting the voltage V1 to connections 140
and 142, respectively.
[0062] FIG. 10H illustrates the programming interface 52 of the
control circuit 39. The programming interface 52 can include a
reprogramming port J2 to allow reprogramming of a microcontroller
U10 (as shown in FIG. 10J) within the microcontroller circuit 56
once the TE management unit 10 is already installed. Five pins of
the reprogramming port J2 can be connected to the microcontroller
circuit 56 via connections 144, 146, 148, 150, and 152, three pins
be connection to ground, and two pins can be connected to voltage
source V1. One of the two pins connected to the voltage source V1
is connected via a resistor R51 (e.g., about 47.5 kilo-ohms).
[0063] FIG. 10I illustrates the power monitor 54 of the control
circuit 39. The power monitor 54 amplifies various voltages from
the power circuit 41 (as shown in FIGS. 11A-11E) and inputs the
amplified voltages to the microcontroller circuit 56 for monitoring
purposes. For example, a voltage V3 (described later) is amplified
via amplifier A1 and connected to the microcontroller circuit 56
via a connection 154. A voltage V4 is amplified via amplifier A2
and connected to the microcontroller circuit 56 via a connection
156. A voltage V5 is amplified via amplifier A3 and resistors R52
(e.g., 1 kilo-ohm), R53 (e.g., 100 ohms), and R54 (e.g., 33
kilo-ohms) and connected to the microcontroller circuit 56 via a
connection 158. A voltage V6 is amplified via amplifier A4 and
resistors R55 (e.g., 1 kilo-ohm), R56 (e.g., 1.8 kilo-ohms), and
R57 (e.g., 1 kilo-ohm) and connected to the microcontroller circuit
56 via a connection 160.
[0064] FIG. 10J illustrates the microcontroller circuit 56 of the
control circuit 39. The microcontroller circuit 56 can incorporate
the microcontroller U10, which can include a microprocessor and/or
a digital signal processor, a digital-to-analog converter, and an
analog-to-digital converter. In some embodiments, the
microcontroller U10 can be a digital signal controller, such as
Part No. MC56F8025, manufactured by Freescale Semiconductor.RTM..
The following paragraphs describe pin assignments for the
microcontroller U10 according to one embodiment of the
invention.
[0065] The connection 136, which is the receiving line of the
serial port 48, can be connected to pin 1 of the microcontroller
U10. The connection 142, which is the clock line of the I2C bus
line to the memory circuit 50, can be connected to pin 2 of the
microcontroller U10. The connection 138, which is the transmission
line of the serial port 48, can be connected to pin 3 of the
microcontroller U10. The connection 106, which is the output of the
multiplexer U1 in the tachometer circuit 44, can be connected to
pin 4 of the microcontroller U10. Pin 5 of the microcontroller U10
can be connected to a voltage divider circuit including the voltage
V1, a resistor R58 (e.g., about 10 kilo-ohms), and a resistor R59
(e.g., about 10 kilo-ohms). The connection 160, which is an
amplified voltage signal of the voltage V6 from the power monitor
circuit 54, can be connected to pin 6 of the microcontroller U10.
The connection 154, which is an amplified voltage signal of the
voltage V3 from the power monitor circuit 54, can be connected to
pin 7 of the microcontroller U10. The connection 156, which is an
amplified voltage signal of the voltage V4 from the power monitor
circuit 54, can be connected to pin 8 of the microcontroller U10.
The connection 132, which is the enable input for the latch U4 of
the alarm circuit 46, can be connected to pin 9 of the
microcontroller U10. The connection 98, which is the enable input
for the multiplexer U1 of the tachometer circuit 44, can be
connected to pin 10 of the microcontroller U10. Pins 11, 29, 35,
16, 23, and 12, 17, 28, and 36 of the microcontroller U10 can be
connected to a capacitor circuit including capacitors C9-C13 in
connection with the voltage V1 (at pins 11, 29, 35, 16, and 23) and
ground (at pins 12, 17, 28, and 36), with the configuration shown
in FIG. 10J. The capacitors C9 and C11 can have a capacitance of
about 1 microfarad, the capacitors C10 and C12 can have a
capacitance of about 0.1 microfarads, and the capacitor C13 can
have a capacitance of about 10 microfarads.
[0066] The connection 64, which is an input from the temperature
sensor S4, can be connected to pin 13 of the microcontroller U10.
The connection 62, which is an input from the temperature sensor
S3, can be connected to pin 14 of the microcontroller U10. The
connection 60, which is an input from the temperature sensor S2,
can be connected to pin 15 of the microcontroller U10. The
connection 58, which is an input from the temperature sensor S1,
can be connected to pin 16 of the microcontroller U10. The
connection 146 from the programming interface 52 can be connected
to pin 19 of the microcontroller U10. The connection 104, which can
lead to inputs in both the tachometer circuit 44 and the alarm
circuit 46, can be connected to pin 20 of the microcontroller U10.
The connection 152 from the programming interface 52 can be
connected to pin 21 of the microcontroller U10. The microcontroller
U10 can output a voltage V7 (described below), at pin 22, to the
power circuit 41. The microcontroller U10 can output another
voltage V8 (described below), at pin 23, to the power circuit 41.
The microcontroller U10 can output another voltage V9 (described
below), at pin 24, to the power circuit 41.
[0067] The connection 158, which is an amplified voltage signal
from the voltage V5 from the power monitor circuit 54, can be
connected to pin 25 of the microcontroller U10. The connection 134,
which is the data input line to the latch U4 in the alarm circuit
46, can be connected to pin 26 of the microcontroller U10. The
connection 100, which can lead to inputs to both the tachometer
circuit 44 and the alarm circuit 46, can be connected to pin 27 of
the microcontroller U10. The connection 140, which is the data line
of the I2C bus line to the memory/external interface 50, can be
connected to pin 30 of the microcontroller U10. The microcontroller
U10 can output another voltage V10 (described below), at pin 31, to
the power circuit 41. The connection 78, which is the PWM input to
the first enclosure fan 36, can be connected to pin 32 of the
microcontroller U10. The connection 80, which is the PWM input to
the second enclosure fan 36, can be connected to pin 33 of the
microcontroller U10. The connection 76, which is the PWM input to
the second ambient fan 34, can be connected to pin 39 of the
microcontroller U10. The connection 74, which is the PWM input to
the first ambient fan 34, can be connected to pin 40 of the
microcontroller U10. The connection 150 from the programming
interface 52 can be connected to pin 41 of the microcontroller U10.
The connection 102, which can lead to inputs to both the tachometer
circuit 44 and the alarm circuit 46, can be connected to pin 42 of
the microcontroller U10. The connection 144 from the programming
interface 52 can be connected to pin 43 of the microcontroller U10.
The connection 148 from the programming interface 52 can be
connected to pin 44 of the microcontroller U10.
[0068] FIG. 11A illustrates the power circuit 41. The power circuit
41 can include a fan power circuit 162 (further illustrated in FIG.
11B), a TE power circuit 164 (further illustrated in FIGS. 11C and
11D), and a unit power circuit 166 (further illustrated in FIG.
11E).
[0069] FIG. 11B illustrates the fan power circuit 162. In some
embodiments, each fan 34, 36 can include four connections: power in
connections, return power connections, tachometer outputs (as
described with respect to the tachometer circuit 44 above), and PWM
inputs (as described with respect to the fan speed control circuit
42 above). The power in and return power connections can provide or
remove power to the fans 34, 36. The power in and return power
connections, as shown in FIG. 11B, can receive DC power from a
switcher circuit controlled by the microcontroller U10. The voltage
V8 from the microcontroller U10, which is an oscillating (i.e.,
PWM) signal, and the voltage V1 turn on transistors Q5 and Q6,
which can switch on a high-side gate driver U11 to provide a
boosted voltage (i.e., the voltage V2) to a gate of MOSFET Q7.
Input to a drain of the MOSFET Q7 can come from the unit power
circuit 166, described below, via a connection 168. The voltage V2
can be provided through a diode D3 (rated for 100 volts, 1 ampere)
to the high-side gate driver U11 and also to charge a capacitor C14
(e.g., 1.0 microfarads, rated for 100 volts). When the high-side
gate driver U11 is switched off, the capacitor C14 can still
provide a boosted voltage to the MOSFET Q7. Resistors R60-R62 can
provide a voltage divider circuit for the transistors Q5 and Q6.
The resistors R60, R61, and R62 can be 2.1 kilo-ohms, 1 kilo-ohm,
and 1 kilo-ohm, respectively. The switcher circuit can also include
resistors R63 (e.g., 47.5 kilo-ohms), R64 (10 kilo-ohms), R65 (15
ohms), and C15 (47 microfarads, rated for 25 volts).
[0070] Following the source of the MOSFET Q7 can be an
inductor-capacitor circuit including voltage clamping diode D4, a
parallel inductor L1 (e.g., 47 micro-henries, rated for 2.7
amperes), and parallel capacitors C16 (e.g., 0.1 microfarads, rated
for 100 volts) and C17 (e.g., 1500 microfarads, rated for 35
volts). Following the inductor-capacitor circuit can be the input
line to the power in connections for the fans 34, 36 (four fans in
total), and the circuit can be completed via the return power
connections from the fans 34, 36 (e.g., to ground). For example,
power in to the first enclosure fan 36 can be received at
connection 170 and return through connection 172, power in to the
second enclosure fan 36 can be received at connection 174 and
return through connection 176, power in to the first ambient fan 34
can be received at connection 178 and return through connection
180, and power in to the second ambient fan 34 can be received at
connection 182 and return through connection 184. In some
embodiments, the tachometers (i.e., from the tachometer circuit 44)
are connected to the return power connections 172, 176, 180, and
184 to determine the speed of the fans 34, 36.
[0071] A voltage divider including resistors R66 (e.g., 100
kilo-ohms) and R67 (e.g., 6.34 kilo-ohms) can provide the feedback
voltage V3 to the power monitor circuit 54. The microcontroller U10
can use an amplified signal of the voltage V3 to monitor an output
of the switching circuit and adjust the oscillating PWM signal
(i.e., the voltage V8) accordingly. Also included after the return
power connection is sensing resistor R68 (e.g., 0.005 ohms) and
capacitor C18 (e.g., 0.1 microfarads, rated for 50 volts). The
voltage V5 of the power return connection, can be directed to the
power monitor circuit 54 for monitoring. For example, if too much
current is being conducted through resistor R68, as would be seen
by the voltage V5, the controller 38 can limit the input voltage
V8. In addition, a voltage V11 can be monitored at the power in
connections. The input voltage V8 can be a fixed voltage and can
regulate a desired output voltage to the fans 34, 36 within about
+/-1.0 Vdc. In some embodiments, the desired output voltage at the
power in connections to the fans 34, 36 can be about 12.0 Vdc, with
an output current up to about 2.7 amperes.
[0072] FIGS. 11C-11D illustrate the TE power circuit 164. The TE
power circuit 164 can provide power to the TE modules 26. The TE
power circuit 164 can have a first switching circuit, similar to
the fan power circuit 162, which can withstand higher power inputs.
The circuits of FIGS. 11C and 11D are connected via connections 186
and 188.
[0073] As shown in FIG. 11C, the voltage V7 from the
microcontroller U10, which is an oscillating (i.e., PWM) signal,
and the voltage V1 can turn on transistors Q8 and Q9, which can
switch on a high-side gate driver U12 to provide a boosted voltage
(i.e., the voltage V2) to a gate of MOSFET Q10. Input to a drain of
the MOSFET Q10 can come from the unit power circuit 166, described
below, via the connection 168. The voltage V2 can be provided
through a diode D5 (e.g., rated for 100 volts, 1 ampere) to the
high-side gate driver U12 and also to charge a capacitor C19 (e.g.,
1.0 microfarads, rated for 100 volts). When the high-side gate
driver U12 is switched off, the capacitor C19 can still provide a
boosted voltage to the MOSFET Q10. Resistors R69-R71 can provide a
voltage divider circuit for the transistors Q8 and Q9. In addition,
when the high-side gate driver U12 is switched on, power can be
provided to charge the capacitor C19 via the voltage V10 from the
microcontroller U10 and a circuit including resistors R72-R75,
schottke diodes D6 and D7, zener diode D8, capacitor C20, and
transistor Q11. As a result, a boosted voltage can be provided to
the drain of the MOSFET Q10 at all times, whether the driver U12 is
switched on or off.
[0074] The resistors R69, R73, and R75 can be about 2.1 kilo-ohms,
the resistors R70 and R71 can be about 1 kilo-ohm, the resistor R72
can be about 330 ohms, and the resistor R74 can be about 100
kilo-ohms. The capacitor C20 can be about 1.0 microfarads (rated
for 100 volts) and the zener diode D8 can have a 15-volt breakdown
voltage. The switcher circuit can also include resistors R76 (e.g.,
47.5 kilo-ohms), R77 (10 kilo-ohms), R78 (15 ohms), and C21 (47
microfarads, rated for 25 volts).
[0075] Following the source of the MOSFET Q10 can be an
inductor-capacitor circuit including voltage clamping diode D9, a
parallel inductor L2 (e.g., 220 micro-henries, rated for 27
amperes), and parallel capacitors C22 (e.g., 0.1 microfarads, rated
for 100 volts), C23 (e.g., 2700 microfarads, rated for 35 volts),
and C24 (e.g., 2700 microfarads, rated for 35 volts). Following the
inductor-capacitor circuit can be a voltage divider including
resistors R79 (e.g., 100 kilo-ohms) and R80 (e.g., 6.34 kilo-ohms)
that provides the feedback voltage V4 to the power monitor circuit
54. The microcontroller U10 can use an amplified signal of the
voltage V4 to monitor an output of the switching circuit and adjust
the oscillating PWM signal (i.e., voltage V7) accordingly. Also
following the inductor-capacitor circuit are resistor R81 (e.g.,
0.002 ohms), resistor R82 (e.g., 0.002 ohms) and capacitor C25
(e.g., 0.1 microfarads, rated for 50 volts). The inductor-capacitor
circuit, through the resistors R81-R82 and the capacitor C25, leads
to the connections 186 and 188.
[0076] As shown in FIG. 11D, the TE power circuit 164 includes an
H-bridge with two identical circuits. The voltage V2 is provided to
high-side gate drivers U13 and U14, which output voltages to gates
of MOSFETs Q12 and Q13, respectively. Input to a drain of the
MOSFETs Q12 and Q13 can come from the positive output of the first
switching circuit via the connection 186. The voltage V2 can also
be provided through diodes D10 and D11 (rated for 100 volts, 1
ampere) to the high-side gate drivers U13 and U14 and also to
charge capacitors C26 and C27 (e.g., 1.0 microfarads, rated for 100
volts). When the high-side gate drivers U13 and U14 are on, power
can be provided to charge the capacitors C26 and C27 via the
voltage V10 from the microcontroller U10 and circuits including
resistors R82-R85 and R86-R89, schottke diodes D12-D13 and D14-D15,
zener diodes D16 and D17, capacitors C28 and C29, and transistors
Q14 and Q15.
[0077] The resistors R82, R86 and R88 can be about 330 ohms, the
resistors R83, R85, R87, and R89 can be about 2.1 kilo-ohms, the
resistor R84 can be about 100 kilo-ohms, and the resistor R74 can
be about 100 kilo-ohms. The capacitors C28 and C29 can be about 1.0
microfarads (rated for 100 volts) and the zener diodes D16 and D17
can have a 15-volt breakdown voltage. The identical circuits can
also include resistors R90 and R91 (e.g., both 10 kilo-ohms) and
resistors R92 and R93 (15 ohms).
[0078] One of the two identical circuits can be switched on, while
the other is switched off, and vice versa, to provide forward or
reverse polarity power to the TE modules 26, allowing the TE
management unit 10 to work in a cooling mode or a heating mode. The
microcontroller U10 can control such switching via the input
voltage V9, as described below.
[0079] When the input V9 is high, current can flow through a
resistor R94 (e.g., 10 kilo-ohms), through the base to the emitter
of transistor Q16 to ground. This also can allow current flow from
voltage source V1 through a resistor R95 (e.g., 330 ohms), through
the collector of the transistor Q16 to ground. As a result, no
current flows to the base of transistor Q17 and it is not active.
Because the transistor Q17 is not active, no current is being
pulled through the resistor R90 to the collector of transistor Q17,
and thus, no voltage is provided to turn on the high-side gate
driver U13. In addition, when the input V9 is high, current can
flow through a resistor R96 (e.g., 330 ohms), through the base to
the emitter of transistor Q18 to ground. This pulls current from
voltage V2 through the resistor R91, through the collector of the
transistor Q18 to ground, which then allows a voltage to be
provided to the high-side gate driver U14, thus turning it on.
Therefore, when the input V9 is high, the high-side gate driver U13
is off and the high-side gate driver U14 is on.
[0080] When the input V9 is low, the transistor Q16 is not in
active mode, and thus, current can flow from voltage source V1
through the resistor R95 to turn on the transistor Q17, which in
turn pulls current from voltage source V2 through the resistor R90,
allowing the high-side gate driver U13 to turn on. Also, when the
input V9 is low, the transistor Q18 is not in active mode, and
thus, no voltage is provided to the high-side gate driver U14.
Therefore, when the input V9 is low, the high-side gate driver U13
is on and the high-side gate driver U14 is off.
[0081] When the high-side gate driver U13 is on, voltage is applied
to switch on the MOSFET Q12, which in turn provides voltage (from
connection 186) supplied to the TE modules 26 at the connections
190 and 192. Also, when the high-side gate driver U13 is on,
voltage from V2 is applied across a the resistor R90 and a resistor
R97 (e.g., 10 kilo-ohms) to ground, which can switch on a MOSFET
Q19. The active MOSFET Q19 provides a return line from the TE
modules 26 (at the connections 194 and 196) to ground. While in
this configuration, the TE management unit 10 can be in a cooling
mode.
[0082] When the high-side gate driver U14 is on, voltage is applied
to switch on the MOSFET Q13, which in turn provides voltage (from
connection 186) supplied to the TE modules 26 at the connections
194 and 196. Also, when the high-side gate driver U14 is on,
voltage from V2 is applied across the resistor R91 and a resistor
R98 (e.g., 10 kilo-ohms) to ground, which can switch on a MOSFET
Q20. The active MOSFET Q20 then provides a return line from the TE
modules 26 (at the connections 190 and 192) to ground. While in
this configuration, the TE management unit 10 can be in a heating
mode.
[0083] In some embodiments, the high-side gate drivers U11-U14 can
each be Part No. FAN7361, manufactured by Fairchild
Semiconductor.RTM., the transistors Q5, Q6, Q8, Q9, Q15, Q16, Q17
and Q18 can be NPN transistors, such as Part No. MMBTH24,
manufactured by Fairchild Semiconductor.RTM., and the MOSFETs Q7,
Q10, Q12, Q13, Q19, and Q20 can be Part No. IRF520NPBF,
manufactured by International Rectifier.
[0084] The voltage V6 at connections 194 and 196 can be directed to
the power monitor circuit 54 for monitoring. In addition, a voltage
V12 can be monitored at the connections 190 and 192. The input
voltage V7 (as shown in FIG. 11C) can be a variable voltage and can
regulate a desired output voltage level to the TE modules 26 within
about +/-1.0 Vdc. In some embodiments, the desired output voltage
to the TE modules 26 can be between about 15 Vdc and about 60 Vdc,
depending input voltage to the TE management unit 10, with an
output current up to about 13.5 amperes. In one embodiments, the
output voltage to the TE modules 26 can be between about 0 Vdc and
3.0 Vdc less than the input voltage to the TE management unit 10.
As earlier discussed, the TE power circuit 164 is capable of
switching the polarity of the output voltage to the TE modules 26
so the TE management unit 10 can operate in a cooling mode or a
heating mode.
[0085] FIG. 11E illustrates the unit power circuit 166. The unit
power circuit 166 can provide power to the TE management unit 10,
including the fan power circuit 162, the TE power circuit 164, and
the control circuit 39. The input voltage to the unit power circuit
166 can be supplied at connections 198 and 200 (with return lines
at connections 202 and 204). In some embodiments, the input
voltage, such as from power input 203 in FIG. 12, can range from
about 18 Vdc to about 60 Vdc, and an input current can be as high
as about 20 amperes, direct current. The unit power circuit 166 can
be reverse-polarity protected with diode D18, such as Part No.
30CPF12Pbf, a fast-soft recovery rectifier diode, manufactured by
International Rectifier, among others. In other embodiments, the
input voltage can range from about 115 volts, alternate current
(Vac) to about 230 Vac, at about 50 Hertz to 60 Hertz. In such
embodiments, the unit power circuit 166 can include an additional
transformer circuit (not shown) to produce a direct current voltage
input at the connections 198, 200, 202, and 204.
[0086] The unit power circuit 166 can have a series of filtering
capacitors C30-C33, followed by a voltage regulator U15, such as a
high voltage step down switching regulator (e.g., Part No. LM5008,
manufactured by National Semiconductor). The filtering capacitors
C30, C31, C32, and C33 can have a capacitance of 0.001 microfarads,
0.001 microfarads, 10 microfarads, and 0.1 microfarads,
respectively, and can all be rated for 100 volts. The input
voltage, after diode D18, can be connected to pin 8 of the
regulator U15. The input voltage can also be connected to pin 6,
with a resistor R99 (e.g., 232 kilo-ohms) in between. Pins 3, 7,
and 4 can be connected to the return line, with a resistor R100
(e.g., 232 kilo-ohms) between pin 3 and the return line, and a
capacitor C34 (e.g., 0.1 microfarads, rated for 50 volts) between
pin 7 and the return line. Pin 1 of the regulator U15, through
inductor L3 (e.g., 470 micro-Henries, rated for 0.79 amperes),
outputs the voltage V2 for the TE management unit 10. A feedback
voltage from a voltage divider including the voltage V2 and
resistors R101 (e.g., 10 kilo-ohms) and R102 (e.g., 2550 ohms) can
be fed back to pin 5 of the regulator U15. Also, pin 2 of the
regulator U15 can be connected to the output of pin 1, with
capacitor C35 (e.g., 0.01 microfarads) in between, followed by
diode D19, connected to ground.
[0087] The voltage V2 is connected to another voltage regulator U16
to produce the voltage V1 Transient protection capacitors C36-C39
can also be present before and after the regulator U16. The output
of the regulator U16, connected through a resistor R103 to ground,
can be the voltage V1 for the TE management unit 10. A fuse F1 can
be provided before voltage source V1 to prevent current overload.
The fuse F1 can be a resettable fuse (i.e., a PTC). In some
embodiments, the capacitors C36, C37, C38, and C39 can have a
capacitance of 47 microfarads (rated for 25 volts), 0.1 microfarads
(rated for 50 volts), 10 microfarads (rated for 6.3 volts), and 0.1
microfarads (rated for 50 volts), respectively. The voltage
regulator U16 can be Part No. LD1117DT, manufactured by ST
Microelectronics.
[0088] In addition, the input voltage, after diode D18, can be
provided to the fan power circuit 162 and the TE power circuit 164,
via the connection 168. A bulk capacitor C40 (e.g., 4700
microfarads, rated for 80 volts) can be connected to the connection
168 to provide power to the fan power circuit 162 and the TE power
circuit 164 in case of any transients at the input connections 198
and 200.
[0089] The wiring diagram of FIG. 12 illustrates the connections
between the controller 38 and elements of the TE management unit
10. In some embodiments, the control circuit 39 and power circuit
41 can be housed in a junction box (not shown) remote from the TE
management unit 10. FIG. 12 also shows a power input 203 for the
controller 38. In addition, the control circuit 39 and the power
circuit 41 can be custom printed on a printed circuit board (PCB)
205, which is then housed in the junction box. FIG. 13 illustrates
a top side of the PCB 205 according to some embodiments of the
invention.
[0090] FIGS. 14A-14G are flow charts of a control scheme according
to one embodiment of the invention for use with the TE management
unit 10. The control scheme of FIGS. 14A-14G can be implemented via
the control and power circuits 39, 41 of the controller 38.
[0091] FIGS. 14A-14B illustrate a main routine for the TE
management unit 10. After startup 206, the controller 38 proceeds
to step 208, which can include flashing red and green LEDS (i.e.,
diodes D2 and D1 of the alarm circuit 46) and toggling the alarm
outputs for a first time period (e.g., four seconds). The
controller 38 can then determine whether a loop counter is less
than a preset integer (e.g., ten) at step 210. If the loop counter
is less than the preset integer, the controller 38 can proceed to
step 212, which can include the controller 38 determining if a fan
feedback voltage (i.e., the voltage V3) is less than a fan setpoint
voltage and if the PWM signal (i.e., the input voltage V8) is less
than or equal to 80% duty cycle. The controller 38 can then either
proceed to step 214 if the fan feedback voltage is less than the
fan setpoint voltage and the PWM signal is less than or equal to
80%, or to step 216 if the fan feedback voltage is more than the
fan setpoint voltage or the PWM signal is less than or equal to
80%. At step 214, the controller 38 increases the PWM signal one
step (i.e., one timing interval). At step 216, the controller 38
decreases the PWM output one step. Following either step 214 or
step 216, the controller 38 restricts the PWM signal to between 0%
to 80% duty cycle at step 218 (i.e., to keep the duty cycle within
a proper operating range). The controller 38 then checks a fan over
current comparator (i.e., the voltage V4) at step 220. If the fan
over current comparator is low, the controller 38 sets the updated
PWM signal (i.e., updates the input voltage V8) and resets the loop
count to zero at step 222. If the fan over current comparator is
high, the controller 38 first proceeds to step 224 and sets the fan
PWM signal to 0% duty cycle, then proceeds to step 222.
[0092] If, at step 210 the loop count is greater than the preset
integer, the controller 38 proceeds to step 226 and calculates
various temperatures and voltages, checks the temperature sensors
S1-S4 for any faults, and increments the loop counter. Following
either step 222 or 226, the controller 38 proceeds to step 228
(FIG. 14B) and determines if a second time period (e.g., 1 second)
has passed since the last entry (i.e., the last time the PWM signal
was updated). If the second time period has not passed, the
controller 38 returns to step 210. If the second time period has
passed, the controller 38 proceeds to step 230 and calculates the
speed of the fans 34, 36 (e.g., using the tachometer inputs).
Following step 230, the controller 38 determines if a third time
period (e.g., 2 seconds) has passed since startup (step 206) by
checking a startup timer at step 232. If not, the controller 38
proceeds to step 234 and adjusts the enclosure fan PWM signal,
toggles the polarity of the voltage output to the TE modules 26
(i.e., via the voltage V9), and increments the startup timer. If
the third time period from step 232 has passed, the controller 38
proceeds to step 236 and determines if the time is between the
third time period from step 232 and a fourth time period (e.g., 4
seconds after startup). If so, the controller 38 proceeds to step
238 and adjusts the ambient fan PWM signal and increments the
startup timer. If not, the controller 38 instead proceeds to step
240 and determines if the time after startup is past or is equal to
the fourth time period. If so, the controller 38 proceeds to step
242 and adjusts the PWM signal for both the enclosure fan 36 and
the ambient fan 34. If not, the controller 38, at step 244, sets
and clears any delayed alarm outputs, maps the alarm outputs to
their respective alarms (i.e., at the alarm circuit 46), and
performs any miscellaneous "1-second updates," such as checking a
door switch or a door alarm (via the tachometer circuit 44), then
proceeds back to step 210 in FIG. 14A.
[0093] FIG. 14C illustrates a routine to set the fan PWM signals.
The controller 38 can modulate fan speeds (i.e., via the fan PWM
signals) to maintain a set temperature change across the TE modules
26 as measured by the temperature sensors S1-S4 in the enclosure
loop and the ambient loop. The following routine can be executed
separately for the ambient fans 34 (i.e., using the ambient air
loop temperatures) and the enclosure fans 36 (i.e., using the
enclosure air loop temperatures). After startup 246 of the routine,
the controller 38 determines if the fans 34, 36 are set in a "run"
mode at step 248. If so, the controller 38 calculates an air loop
temperature change (e.g., the difference between enclosure inlet
and outlet temperatures or the ambient inlet and outlet
temperatures) at step 250. Following step 250, the controller 38
determines if the air loop temperature change is greater than a fan
change setpoint plus 3 (or some other set integer) at step 252. If
so, a PWM step change value is set to 100 at step 254. If not, the
controller 38 determines if the air loop temperature change is
greater than the fan change setpoint plus 1 (or some other set
integer) at step 256. If so, the PWM step change value is set to 25
at step 258. If not, the controller 38 determines if the air loop
temperature change is greater than the fan change setpoint minus 1
(or some other set integer) at step 260. If so, the PWM step change
value is set to 5 at step 262. If not, the PWM step change value is
set to 25 at step 264. Following any one of steps 254, 258, 262, or
264, the controller 38 proceeds to step 266 and determines if any
alarms are active (e.g., airflow alarm, temperature or sensor
failure alarm, power fault alarm, etc. described above). If an
alarm is active, the PWM step change value is set to 100 and the
PWM step change value is then subtracted from the PWM signals at
step 268. Following step 268, the controller 38 restricts the
enclosure fan PWM signal between 75% and 100% and the ambient fan
PWM signal between 25% to 100% at step 270, to keep the fans 34, 36
operating within desired, or operable, speed ranges. If, for
example, the PWM signal is outside the ranges (such as 125%), the
PWM signal is then set to its low or high limit value (such as
100%, in this example). The controller 38 then proceeds to step 272
and sets the updated PWM signal (i.e., updates the input voltage
V8) and tests the fan speeds for validity (e.g., using the
tachometer circuit 44). Following step 272, the routine is
completed 274. In some embodiments, the target temperature change
in the ambient air loop or the enclosure air loop can be about 7
degrees Celsius +/- 2 degrees Celsius.
[0094] If, at step 266, there are no alarms active, the controller
38 determines, at step 276, if the air loop temperature change is
greater than the fan change setpoint. If not, the PWM step change
value is subtracted from the PWM signals at step 278. If so, the
PWM step change value is added to the PWM signals at step 280.
Following either step 278 or 280, the controller 38 proceeds to
step 270 (described above).
[0095] If, at step 248, the controller 38 determines that the fans
34, 36 are not in a "run" mode, the controller 38 determines if the
fans 34, 36 are in an "off" mode at step 282. If the fans 34, 36
are in the off mode, the controller 38 proceeds to step 284 and
sets the PWM signals to 0%, then proceeds to step 272. If the
controller 38 determines at step 282 that the fans are not in off
mode, the controller 38 proceeds straight to step 272.
[0096] FIG. 14D illustrates a flowchart for an interrupt service
routine (ISR) used by the controller 38 to calculate the voltage
output to the TE modules 26 (i.e., the "TE voltage output"). The
controller 38 can modulate the TE voltage output to maintain a
desired heating or cooling temperature set-point. The controller 38
can use a single temperature control zone as the input for TE
voltage output control. For example, the controller 38 can use the
inlet temperature of the enclosure air loop (e.g., as obtained from
the temperature sensor S1) as an input to control the TE voltage
output. After startup 286 of the ISR, the controller 38 determines
whether it is currently switching between heating and cooling modes
at step 288. If so, the controller 38 sets a "TE reset" flag at
step 290. If the controller 38 is not switching modes, or following
step 290, the controller 38 determines if the temperature in the
enclosure inlet 11 is greater than a cool temperature setpoint at
step 292 (e.g., via temperature sensor S1). If so, the controller
38 sets the TE management unit 10 to the cooling mode at step 294,
then proceeds to step 296 and determines if the air loop
temperature change is greater than a maximum air loop temperature
change. If so, the controller 38 sets the TE voltage output to 0
volts at step 298. The controller 38 then confirms the TE voltage
output is within a range of greater than or equal to 0 volts and
less than or equal to 24 volts, and adjusts it accordingly if it is
not, at step 300. Following step 300, the ISR is completed at step
302.
[0097] If, at step 292, the controller 38 determines that the
enclosure temperature is not greater than the cool temperature
setpoint, the controller 38 proceeds to step 304 and determines if
the enclosure inlet temperature is less than a warm temperature
setpoint. If so, the controller 38 sets the TE management unit 10
to the heating mode at step 306, then proceeds to step 296. If not,
the controller 38 does nothing and proceeds to step 296 and
determines if the air loop temperature change is greater than a
maximum air loop temperature change.
[0098] If, at step 296, the controller 38 determines that the air
loop temperature change is not greater than a maximum air loop
temperature change, the controller 38 proceeds to step 308. At step
308, the controller 38 sets and records a setpoint error value as
the difference between the enclosure temperature and the
temperature setpoint, then sets a "sum of setpoint errors" value as
the sum of the last 16 setpoint error values recorded. If the sum
of setpoint errors value is above a maximum value, the controller
38 limits the sum of setpoint errors value to the maximum value.
The controller 38 then sets a voltage adjust value as the product
of a constant Kp and the setpoint error value plus a product of
another constant Ki and the sum of setpoint errors value. The
controller 38 then proceeds to step 310 and determines if the TE
management unit 10 is in cooling mode. If so, the controller 38
proceeds to step 312 and adds the voltage adjust value to the
current TE voltage output value. If not, the controller 38 proceeds
to step 314 and subtracts the voltage adjust value from the current
TE voltage output value. Following either step 312 or step 314, the
controller 38 determines if an enclosure temperature alarm (e.g.,
the temperature or sensor failure alarm or the airflow alarm) is
active at step 316. If so, the controller 38 sets the TE voltage
output to 18 Vdc at step 318. If there is no enclosure temperature
alarm active at step 316, or following step 318, the controller 38
determines if a fan alarm (e.g., the airflow alarm or the power
fault alarm) is active at step 320. If so, the controller 38 sets
the TE voltage output to 0 volts at step 322. If there is no fan
alarm active at step 320, or following step 322, the controller 38
proceeds to step 300 and confirms the TE voltage output is within a
range of greater than or equal to 0 volts and less than or equal to
24 volts, and adjusts the TE voltage output accordingly if it is
not. Following step 300, the ISR is completed at step 302. The
temperature set points in steps 292 and 304 can be factory-set or
adjusted through a programming interface (e.g., the programming
interface 52), display board, or other user interface by a user.
Also, in some embodiments, if the TE management unit 10 is between
temperature set-points upon startup, the controller 38 can default
to heating mode.
[0099] FIG. 14E illustrates a flowchart for an ISR used by the
controller 38 to calculate the TE module PWM output (i.e., the
voltage V7). After startup 324 of the ISR, the controller 38
determines whether the TE voltage feedback value (i.e., the
feedback voltage V4) is less than a TE voltage setpoint at step
326. If so, the TE PWM output is increased one step at step 328. If
not, the PWM output is decreased one step at step 330. Following
either step 320 or 330, the controller 38 determines if the TE PWM
output is set to greater than 100% duty cycle at step 332. If so,
the controller 38 limits the TE PWM output to 100% at step 334. If
the TE PWM output is not greater than 100% at step 332, or
following step 334, the controller 38 determines if the TE PWM
output is either less than 0% or the TE over current comparator's
output is high at step 336 (e.g., from the voltage V6 or the
voltage V12). If either is true, the TE PWM output is set to 0% at
step 338. If one or both are not true at step 336, or following
step 338, the controller 38 sets the updated TE module PWM output
signal (i.e., updates the input voltage V7) and resets the ISR
timer at step 340. Following step 340, the ISR is completed at step
342.
[0100] FIG. 14F illustrates a flowchart for a fan over-current ISR.
After startup 334 of the ISR, the controller 38 determines, on the
rising edge of a clock signal (i.e., as a rising edge interrupt),
whether an amplified voltage on a fan current sense resister (i.e.,
the voltage V5 from resistor R68) is greater than a fan current
limit (step 336). The fan current limit can be set by a
digital-to-analog converter of the microcontroller U10. If the
voltage on the fan current sense resister is greater than the fan
current limit at step 336, the controller 38 proceeds to step 338
and stops the fans 34, 36. In particular, in step 338, the
controller 38 sets the PWM signal value (i.e., the voltage V8) to
0% duty cycle, updates the PWM signal, and resets the ISR. If the
voltage on the fan current sense resister is not greater than the
fan current limit at step 336, or following step 338, the
controller 38 determines on the falling edge of a clock signal
(i.e., as a falling edge interrupt), whether the amplified voltage
on the fan current sense resister is less than the fan current
limit (step 340). If so, the controller 38 resets the ISR at step
342. If not, or following step 342, the ISR is completed at step
344.
[0101] FIG. 14G illustrates a flowchart for a TE over-current ISR.
After startup 346 of the ISR, the controller 38 determines, on the
rising edge of a clock signal (i.e., as a rising edge interrupt),
whether an amplified voltage on a TE current sense resister is
greater than a TE current limit (step 348). The TE current limit
can be set by a digital-to-analog converter of the microcontroller
U10. If the voltage on the TE current sense resister is greater
than the TE current limit at step 348, the controller 38 proceeds
to step 350 and stops providing power to the TE modules 26. In
particular, in step 350, the controller 38 sets the TE module PWM
output to 0%, updates the TE module PWM output, and resets the ISR.
If the voltage on the TE current sense resister is not greater than
the TE current limit at step 348, or following step 350, the
controller 38 determines on the falling edge of a clock signal
(i.e., as a falling edge interrupt), whether the amplified voltage
on the TE current sense resister is less than the TE current limit
(step 352). If so, the controller 38 resets the ISR at step 354. If
not, or following step 354, the ISR is completed at step 356.
[0102] In some embodiments, as shown in FIGS. 15A and 15B, the TE
management unit 10 can incorporate a separator printed circuit
board (PCB) 358, in place of the panel 32 (shown in FIGS. 1A-1B).
The separator PCB 358 can extend the physical length and width of
the TE management unit 10. The separator PCB 358 can be used to
integrate several functions of the controller 38, as well as also
separate the cold and warm thermal circuits of the TE modules 26,
as also shown in FIG. 16. Further, the separator PCB 358 can
separate the enclosure side 16 from the ambient side 18 of the TE
management unit 10.
[0103] The separator PCB 358 can be custom-made, and thus, can be
populated with different electronic circuits that perform several
different functions, such as control, regulation, monitoring, etc.
of the TE management unit 10. FIG. 17 illustrates an enclosure side
357 of the separator PCB 358, and FIG. 18 illustrates an ambient
side 359 of the separator PCB 358 according to one embodiment of
the invention. If the TE management unit 10 is mainly used for
cooling the enclosure, the separator PCB 358 can keep delicate
electronic circuits on the enclosure side 357 (e.g., the cool side)
to provide higher reliability.
[0104] The separator PCB 358 can provide some or all of the
electrical and electronic connections for the controller 38 and the
elements of the TE management unit 10. For example, the separator
PCB 358 can include some or all elements necessary to perform the
same functions of the control circuit 39 and power circuit 41
described above (i.e., at least the functions described in flow
charts 13A-13G). Thus, the separator PCB 358 can allow for the TE
modules 26 as well as other components of the TE management unit 10
to reliably connect and interconnect on the traces of the PCB,
rather than using separate circuitry and connectors. The separator
PCB 358 can integrate circuitry without the need, or with minimal
need, for external housings or junction boxes.
[0105] FIG. 19A illustrates a schematic of a power circuit 360,
according to another embodiment of the invention, that can be
implemented on the separator PCB 358. An accompanying control
circuit 361 (illustrated in FIGS. 20A-20G) can be implemented on
another PCB (not shown) remote from and connected to the separator
PCB 358. In other embodiments, both the power circuit 360 and the
control circuit 361 (or the power circuit 41 and the control
circuit 39) can be implemented on the separator PCB 358. As shown
in FIG. 19A, the power circuit 360 can include a main power input
362 (further illustrated in FIG. 19B), a low voltage supply 364
(further illustrated in FIG. 19C), a high voltage supply 366
(further illustrated in FIG. 19D), a bulk power regulator 368
(further illustrated in FIG. 19E), an H-bridge 370 (further
illustrated in FIG. 19F), fan power outputs 372 (further
illustrated in FIG. 19G), and TE stack connections 374 (further
illustrated in FIG. 19H). Dotted lines between the elements of the
power circuit 360 illustrate virtual connections where voltage
inputs are referenced to and from.
[0106] FIG. 19B illustrates the main power input circuit 362. The
input voltage to the TE management unit 10 can be supplied at
connections 198 and 200 (with return lines at connections 202 and
204). Following filtering capacitors C41 and C42 (e.g., 2000
microfarads, rated for 80 volts, and 1.0 microfarads, rated for 100
volts, respectively) can be a reference power voltage V13. The
voltage V13 can be provided to the low voltage supply 364 and the
high voltage supply 366. In addition, the main power input 362 can
include an earth ground reference via connections 376 and 378. In
some embodiments, the input voltage, such as from power input 203
in FIG. 12, can range from about 18 Vdc to about 60 Vdc, and an
input current can be as high as about 20 amperes, direct current.
In other embodiments, the input voltage can range from about 115
volts, alternate current (Vac) to about 230 Vac, at about 50 Hertz
to 60 Hertz. In such embodiments, the main power input circuit 362
can include an additional transformer circuit (not shown) to
produce a direct current voltage input at the connections 198, 200,
202, and 204.
[0107] FIG. 19C illustrates the low voltage supply circuit 364. The
low voltage supply 364 regulates the reference power voltage V13
down to a low supply voltage V14 (e.g., 3.3 volts) to be used by
the H-bridge 370 and the control circuit 361. The low voltage
supply 364 can have a series of filtering capacitors C43-C44,
followed by a voltage regulator U17, such as a high voltage step
down switching regulator (e.g., Part No. LM5008, manufactured by
National Semiconductor). The filtering capacitors C43 and C44 can
have a capacitance of 0.1 microfarads and 1.0 microfarads,
respectively, and can both be rated for 100 volts. The reference
power voltage V13 can be connected to pin 8 of the regulator U17.
The voltage V13 can also be connected to pin 6, with a resistor
R104 (e.g., 232 kilo-ohms) in between. Pins 3, 7, and 4 can be
connected to ground, with a resistor R105 (e.g., 232 kilo-ohms)
between pin 3 and ground, and a capacitor C45 (e.g., 0.1
microfarads) between pin 7 and ground. Pin 1 of the regulator U17,
through inductor L4 (e.g., 470 micro-Henries, rated for 0.79
amperes), outputs the voltage V14 for the TE management unit 10. A
feedback voltage from a voltage divider including the voltage V14
and resistors R106 (e.g., 1 kilo-ohm) and R107 (e.g., 3.46
kilo-ohms) can be fed back to pin 5 of the regulator U17. Also, pin
2 of the regulator U17 can be connected to the output of pin 1,
with capacitor C46 (e.g., 0.1 microfarads, rated for 100 volts) in
between, followed by diode D20, connected to ground. The low
voltage supply 364 can further include capacitors C47 (10
microfarads, rated for 16 volts) and C48 (0.1 microfarads, rated
for 50 volts) for transient protection.
[0108] FIG. 19D illustrates the high voltage supply circuit 366.
The high voltage supply 366 regulates the reference power voltage
V13 down to a high supply voltage V15 (e.g., 12 volts) to be used
by the bulk power regulator 368, the H-bridge 370, and the control
circuit 361. The high voltage supply 366 can have a series of
filtering capacitors C49-050, followed by a voltage regulator U18,
such as a high voltage step down switching regulator (e.g., Part
No. LM5008, manufactured by National Semiconductor). The filtering
capacitors C49 and C50 can have a capacitance of 0.1 microfarads
and 1.0 microfarads, respectively, and can both be rated for 100
volts. The reference power voltage V13 can be connected to pin 8 of
the regulator U18. The voltage V13 can also be connected to pin 6,
with a resistor R108 (e.g., 232 kilo-ohms) in between. Pins 3, 7,
and 4 can be connected to ground, with a resistor R109 (e.g., 232
kilo-ohms) between pin 3 and ground, and a capacitor C51 (e.g., 0.1
microfarads) between pin 7 and ground. Pin 1 of the regulator U17,
through inductor L5 (e.g., 470 micro-Henries, rated for 0.79
amperes), outputs the voltage V15 for the TE management unit 10. A
feedback voltage from a voltage divider including the voltage V15
and resistors R110 (e.g., 13.7 ohms) and R111 (e.g., 2.4 ohms) can
be fed back to pin 5 of the regulator U18. Also, pin 2 of the
regulator U18 can be connected to the output of pin 1, with
capacitor C52 (e.g., 0.1 microfarads, rated for 100 volts) in
between, followed by diode D21, connected to ground. In addition, a
resistor R112 (e.g., 33 kilo-ohms) can be connected between pins 1
and 5. The high voltage supply 366 can further include capacitors
C53 (5600 picofarads, rated for 50 volts), C54 (10 microfarads,
rated for 16 volts), and C55 (0.1 microfarads, rated for 50 volts)
for transient protection. The high voltage V15 can be connected to
the bulk power regulator 368 via a connection 380, with three
diodes D22, D23, and D24 (all rated for 100 volts and 1 ampere) in
between for reverse-voltage protection.
[0109] FIG. 19E illustrates the bulk power regulator circuit 368.
The bulk power regulator circuit 368 regulates the reference power
voltage V13 down to a voltage V16 for use with the H-bridge 370.
The bulk power regulator circuit 368 can include a synchronous buck
controller U19 such as Part No. LM5116, manufactured by National
Semiconductor. Pin 1 of the controller U19 can be connected to the
reference power voltage V13. Pin 1 of the controller U19 can also
be connected to ground with a capacitor C56 (e.g., 0.1 microfarads,
rated for 100 volts) in between. Pin 2 of the controller U19 can be
connected to a voltage divider between the voltage V13 and ground,
including two resistors R113 (e.g., 232 kilo-ohms) and R114 (e.g.,
20 kilo-ohms). In addition, a diode D25 (rated for 100 volts, 1
ampere) separates the input at pin 2 and V13, and a capacitor C57
(e.g., 1.0 microfarads) separates the input at pin 2 and ground.
Pin 3 of the buck controller U19 is connected to ground with a
resistor R115 (e.g., 12.4 kilo-ohms) in between. Pin 4 of the
controller U19 can either be connected to voltage V13 via the
resistor R116 (e.g., 750 kilo-ohms) or connected to ground via a
switch SW1. Pin 5 of the controller U19 can be connected to ground
with a capacitor C58 (e.g., 1 kilo-picofarad) in between. Pin 5 of
the controller U19 can also be connected to pin 16 via resistor
R117 (e.g., 100 kilo-ohms), which is then connected to ground with
a capacitor C59 (e.g., 1.0 microfarads) in between.
[0110] Pins 6, 11, 13, 14, and 21 of the controller U19 can be
connected to ground. Pins 6, 14, and 21 can also be connected to
the voltage V13 with the capacitor C56 in between. Pin 7 of the
controller U19 can be connected to ground with a capacitor C60
(e.g., 0.01 microfarads) in between. Pins 8 and 9 of the controller
U19 can be connected to the output of the controller U19 at pin 10.
For example, pin 8 can be a feedback input. A compensation loop
connected between pins 8 and 9 can include a resistor R118 (e.g.,
27.4 kilo-ohms) and capacitors C61 (e.g., 0.01 microfarads) and C62
(e.g., 1 kilopicofarad). The compensation loop can be connected to
pin 10 via feedback resistors R119 (e.g., 16.4 kilo-ohms), R120
(e.g., 650 ohms), R121 (e.g., 180 ohms), and high power jumper J3
in connection with ground.
[0111] The bulk power regulator 368 further includes a pair of
MOSFETs Q21 and Q22. The source of MOSFET Q21 and the drain of
MOSFET Q22 can be connected. Pins 19 and 15 of the controller U19
can be connected to the gates of the MOSFETs Q21 and Q22,
respectively. The drain of MOSFET Q21 can be connected to the
voltage V13. The source of MOSFET Q22 and pin 12 of the buck
controller U19 can be connected to ground with a resistor R122
(e.g., 0.005 ohms, rated for 1 watt) in between. Pins 16, 18, and
20 of the controller U19 can be connected between the source of
MOSFET Q21 and the drain of MOSFET Q22 via resistor R123, a diode
D26, and a capacitor C63. Also connected between the source of
MOSFET Q21 and the drain of MOSFET Q22 can be the output from pin
10 of the controller U19 with an inductor L6 in between, followed
by an output capacitor bank C64, leading to the regulated, direct
current voltage V16. The output capacitor bank C64 can include ten
10-microfarad capacitors, all rated for 35 volts, and can be
followed by another capacitor C65 (e.g., 680 microfarads, rated for
35 volts). The bulk power regulator 368 can further include an
input capacitor bank, including capacitors C66, C67, C68, and C69
(each 2.2 microfarads, rated for 100 volts) connected to the
voltage V13. In addition, the voltage V15, from the connection 380
can be connected to the input pin 17. The input pin 17 can further
be connected to ground through a capacitor C70 for transient
filtering.
[0112] FIG. 19F illustrates the H-bridge 370. The H-bridge 370
includes two identical circuits. The voltage V15 is provided to
high-side gate drivers U20 and U21, which can provide voltage to
gates of MOSFETs Q23 and Q24. Input to a drain of each MOSFET Q23
and Q24 can come from the voltage V16. The voltage V15 can also be
provided through diodes D27 and D28 (rated for 100 volts, 1 ampere)
to the high-side gate drivers U20 and U21 and also to charge
capacitors C71 and C72 (e.g., 1.0 microfarads, rated for 100
volts), respectively. When one of the high-side gate drivers U20
and U21 is on, power can be provided to charge the respective
capacitor C71 or C72 via the voltage V17 and circuits including
resistors R124-R126 and R127-R129, schottke diodes D29-D30 and
D31-D32, capacitors C73 and C74, and transistors Q25 and Q26.
[0113] The resistors R124 and R127 can be about 2.0 kilo-ohms, the
resistors R125 and R128 can be about 1 kilo-ohm, and the resistors
R126 and R129 can be about 470 ohms. The capacitors C73 and C74 can
be about 1.0 microfarads (rated for 100 volts). The identical
circuits can also include resistors R130 and R131 (e.g., each 10
kilo-ohms), resistors R132 and R133 (e.g., each 15 ohms), and
capacitors C75 and C76 (e.g., each 10 microfarads, rated for 16
volts).
[0114] One of the two identical circuits can be switched on, while
the other is switched off, and vice versa, to provide forward or
reverse polarity power to the TE modules 26, allowing the TE
management unit 10 to work in a cooling mode or a heating mode. The
control circuit 361 can control such switching via the input
voltages V18 and V19, as described below.
[0115] When the voltage V18 is high, current can flow through a
resistor R134 (e.g., 470 ohms), through the base to the emitter of
transistor Q27 to ground. This pulls current from voltage V15
through the resistor R131, through the collector of the transistor
Q27 to ground, which then allows a voltage to be provided to the
high-side gate driver U21, thus turning it on. In addition, when
voltage V18 is high, voltage V19 can be low. When voltage V19 is
low, no current travels to the base of transistor Q28 and it is not
active. Because the transistor Q28 is not active, no current is
being pulled through the resistor R128 to the collector of
transistor Q28, and thus, no voltage is provided to turn on the
high-side gate driver U20. Therefore, when the voltage V18 is high
and the voltage V19 is low, the high-side gate driver U20 is off
and the high-side gate driver U21 is on. Also, the voltage V14 can
be provided at the output of voltage V18 with a resistor R135
(e.g., 232 kilo-ohms) in between.
[0116] When the voltage V18 is low, the transistor Q27 is not in
active mode, and thus, no voltage is provided to the high-side gate
driver U21. Also, when the voltage V18 is low, the voltage V19 is
high, and current is allowed to flow through the transistor Q28,
which in turn pulls current from voltage source V15 through the
resistor R130, allowing the high-side gate driver U20 to turn on.
Therefore, when the voltage V18 is low and the voltage V19 is high,
the high-side gate driver U20 is on and the high-side gate driver
U21 is off.
[0117] When the high-side gate driver U20 is on, voltage is applied
to switch on the MOSFET Q23, which in turn provides voltage V16
supplied to the TE modules 26 (i.e., at voltage V20). Also, when
the high-side gate driver U20 is on, voltage from V15 is applied
across a the resistor R130 and a resistor R136 (e.g., 232
kilo-ohms) to ground, which can switch on a MOSFET Q29. The active
MOSFET Q29 provides a return line from the TE modules 26 (i.e.,
voltage V21) to ground. While in this configuration, the TE
management unit 10 can be in a cooling mode. Also, the voltage V14
can be provided at the output of voltage V19 with a resistor R137
(e.g., 232 kilo-ohms) in between.
[0118] When the high-side gate driver U21 is on, voltage is applied
to switch on the MOSFET Q24, which in turn provides voltage V16
supplied to the TE modules 26 (i.e., at voltage V21). Also, when
the high-side gate driver U21 is on, voltage from V15 is applied
across the resistor R129 and a resistor R138 (e.g., 232 kilo-ohms)
to ground, which can switch on a MOSFET Q30. The active MOSFET Q30
then provides a return line from the TE modules 26 (i.e., voltage
V20) to ground. While in this configuration, the TE management unit
10 can be in a heating mode.
[0119] Both the voltages V18 and V19 can be pulse-width modulated
by the controller 38. In some embodiments, the high-side gate
drivers U20-U21 can each be Part No. FAN7361, manufactured by
Fairchild Semiconductor.RTM., the transistors Q25, Q26, Q27 and Q28
can be NPN transistors, such as Part No. MMBTH24, manufactured by
Fairchild Semiconductor.RTM., and the MOSFETs Q23, Q24, Q29, and
Q30 can be Part No. IRF520NPBF, manufactured by International
Rectifier. In addition, the voltage V16 and ground can each be
connected to the earth ground reference via capacitors C77 and
C78.
[0120] FIG. 19G illustrates the fan power outputs 372. Input power
to four fans 34, 36, via connections 382, 384, 386, and 388 can
come from the voltage V16 from the bulk power circuit 368. Return
voltage from the fans 34, 36, via connection 390, 392, 394, and 396
can lead to ground.
[0121] FIG. 19H illustrates the TE stack connections 374 according
to one embodiment of the invention. Power to the TE stack can come
from voltages V20 and V21 from the H-bridge 370. As previously
described, power to the TE modules 26 can be forward or reverse
polarity depending on whether the TE management unit 10 is in
cooling mode or heating mode. In the illustrated embodiment, the TE
stack (including TE modules TE1-TE12) is arranged in four strings,
with each string including three modules connected in parallel.
[0122] FIG. 20A illustrates a schematic of the control circuit 361,
according to one embodiment of the invention. The control circuit
361 can be implemented on another PCB (not shown) remote from and
connected to the separator PCB 358. In other embodiments, both the
power circuit 360 and the control circuit 361 (or the power circuit
41 and the control circuit 39) can be implemented on the separator
PCB 358. As shown in FIG. 20A, the control circuit 361 can include
a temperature sensor circuit 398 (further illustrated in FIG. 20B),
a fan speed control circuit 400 (further illustrated in FIG. 20C),
a tachometer circuit 402 (further illustrated in FIG. 20D), an
alarm circuit 404 (further illustrated in FIG. 20E), a
memory/external ports circuit 406 (further illustrated in FIG.
20F), a programming interface 408 (further illustrated in FIG.
20G), a solid state (SS) relay drive 409 (further illustrated in
FIG. 20H), and a microcontroller circuit 410 (further illustrated
in FIG. 20I). In one embodiment, these components can be connected
as shown by connections in FIG. 20A and described below. Dotted
lines between the elements of the control circuit 361 illustrate
virtual connections where voltage inputs are referenced to and
from.
[0123] FIG. 20B illustrates the temperature sensor circuit 398 of
the control circuit 361. The temperature sensor circuit 398 can
include four temperature sensors S5-S8. The temperature sensors
S5-S8 can be similar to temperature sensors S1-S4, described above.
Each temperature sensor S5-S8 can have an accompanying sensor
circuit including three resistors and one capacitor: Resistors
R139-R141 and capacitor C79 for sensor S5; resistors R142-R144 and
capacitor C80 for sensor S6; resistors R145-R147 and capacitor C81
for sensor S7; and resistors R148-R150 and capacitor C82 for sensor
S8. In some embodiments, resistors R139, R142, R145, and R148 can
be about 232 kilo-ohms with a 1% tolerance, resistors R140, R143,
R146, and R149 can be about 1 kilo-ohm and resistors R141, R144,
R147, and R150 can be about 10 kilo-ohms. In addition, capacitors
C79-C82 can have a capacitance of about 0.1 microfarads. Each
accompanying sensor circuit can also include an input voltage, V14
(e.g., 3.3. volts).
[0124] The first sensor circuit, including sensor 55, can be routed
to the microcontroller circuit 410 via a connection 412. The second
sensor circuit, including sensor S6, can be routed to the
microcontroller circuit 410 via a connection 414. The third sensor
circuit, including sensor S7, can be routed to the microcontroller
circuit 410 via a connection 416. The fourth sensor circuit,
including sensor S8, can be routed to the microcontroller circuit
410 via a connection 418. In addition, an external sensor circuit,
including resistors R151 (e.g., 10 kilo-ohms) and R152 (e.g., 3.46
kilo-ohms), and capacitor C83 (e.g., 01 microfarad) can be
connected to the microcontroller circuit 410 via a connection 420.
The external sensor circuit can accompany an external sensor S9,
which may be, for example, a door switch or a smoke detector. The
external sensor S9 can receive power from the voltage V15.
[0125] One of the temperature sensors (S5, for example) can be
positioned at the enclosure inlet 11 and another temperature sensor
(S6, for example) can be positioned at the enclosure outlet 13. A
third temperature sensor (S7, for example) can be positioned at the
ambient inlet 15 and a fourth temperature sensor (S8, for example)
can be positioned at the ambient outlet 17. Therefore, temperatures
can be sensed at both the inlets and outlets of the enclosure air
loop and the ambient air loop. The temperature sensors S5-S8 can
have a temperature accuracy of about +/- 2 degrees Celsius.
[0126] FIG. 20C illustrates the fan speed control circuit 400 of
the control circuit 361. The fan speed control circuit 400 can
operate servomotors for each fan 34, 36. In some embodiments, PWM
speed control can be used to operate the servomotors (i.e., via the
fan speed control circuit 400), and open collector tachometers can
be used for feedback (i.e., via the tachometer circuit 402,
described below), allowing full closed-loop digital control for the
fans 34, 36. The fan speed control circuit 400 can connect to PWM
inputs for each fan 34, 36. For example, a connection 422 can lead
to a PWM input for the first ambient fan 34, a connection 424 can
lead to a PWM input for the second ambient fan 34, a connection 426
can lead to a PWM input for the first enclosure fan 36, and a
connection 428 can lead to a PWM input for the second enclosure fan
36.
[0127] The controller 38 can independently speed control each of
the four fans 34, 36 separately. To speed control the first ambient
fan 34 (via connection 422), a PWM signal from the microcontroller
circuit 410 is transmitted to a resistor R153 via a connection 430
and can switch on and off a transistor Q31. The base of the
transistor Q31 can be connected to the resistor R153 and the
emitter of the transistor Q31 can be connected to ground. When the
signal from connection 430 applies a substantial cut-in voltage
across the base-emitter junction, the transistor Q31 becomes active
and allows current flow from the collector to the emitter. This
current is conducted from the voltage source V15, through resistors
R154 and R155, and through the collector and the emitter to ground.
The connection 422 is connected between the resistors R154 and R155
to provide the PWM input to the first ambient fan 34 when the
transistor Q31 is on. This method and configuration is also used to
speed control the second ambient fan 34, and the first and second
enclosure fans 36 as well, via signals through connections 432,
434, and 436, respectively, from the microcontroller circuit 410,
as illustrated in FIG. 20C. The resistor R153, and resistors R156,
R159, and R162, can be about 100 ohms. The resistor R154, and
resistors R157, R160, and R163, can be about 100 kilo-ohms. The
resistor R155, and resistors R158, R161, and R164, can be about 100
ohms. The transistor Q31, and transistors Q32, Q33, and Q34, can be
simple NPN, BJT transistors, such as Part No. 2N222, manufactured
by Fairchild Semiconductors.RTM., among others.
[0128] FIG. 20D illustrates the tachometer circuit 402 of the
control circuit 361. The controller 38 can receive outputs from
open collector tachometers (not shown) in connection with the fans
34, 36 to monitor fan speed, as described above. A connection 438
can be connected to the tachometer output of the first ambient fan
34, a connection 440 can be connected to the tachometer output of
the second ambient fan 34, a connection 442 can be connected to the
tachometer output of the first enclosure fan 36, and a connection
444 can be connected to the tachometer output of the second
enclosure fan 36. Each tachometer output connection 438, 440, 442,
444 can have an accompanying circuit including two resistors and
one capacitor leading to a multiplexer U22: Resistors R165-R166 and
capacitor C84 for the connection 438, leading to pin 4 of the
multiplexer U22; resistors R167-R168 and capacitor C85 for the
connection 440, leading to pin 3 of the multiplexer U22; resistors
R169-R170 and capacitor C86 for the connection 442, leading to pin
2 of the multiplexer U22; and resistors R171-R172 and capacitor C87
for the connection 444, leading to pin 1 of the multiplexer U22.
The resistors, R165, R167, R169, and R171 can be about 100
kilo-ohms. The resistors R166, R168, R170, and R172 can be about 1
kilo-ohms. The capacitors C84-C87 can be about 0.01
microfarads.
[0129] The multiplexer U22 can be an 8-input multiplexer, such as
Part No. 74HC151, manufactured by Philips Semiconductors. Pins 1-4,
which can be coupled to connections 438, 440, 442, and 444 can be
multiplexer inputs of U2. Pins 12-15 can also be multiplexer inputs
and can receive outputs from various override devices (not shown),
such as smoke detectors, door switches, etc., which the controller
38 can monitor. When none of pins 12-15 are connected to override
devices, as illustrated in FIG. 20D, the pins 12-15 can be
connected to ground. In addition, select inputs to pins 9-11 of U22
can be routed from the alarm circuit 404 via connections 446, 448,
and 450, respectively. The output V22 of the multiplexer U22 (from
pin 5) can be routed to the microcontroller circuit 410.
[0130] FIG. 20E illustrates the alarm circuit 404 of the control
circuit 361. The alarm circuit 404 can include four red LEDs and
four green LEDs (not shown) as visual indicators for alarm outputs.
For example, a first alarm output can be connected to a red LED via
connection 452 and a green LED via connection 454, a second alarm
output can be connected to a red LED via connection 456 and a green
LED via connection 458, a third alarm output can be connected to a
red LED via connection 460 and a green LED via connection 462, and
a fourth alarm output can be connected to a red LED via connection
464 and a green LED via connection 466. Alarm outputs can be
controlled via a latch U23.
[0131] As shown in FIG. 20E, the first alarm output is connected to
the latch U23 at pin 4. The red LED of the first alarm output, at
connection 452, is connected directly to the output of pin 4, while
the green LED, at connection 454, is connected via an inverter G1
and a resistor R173. Thus, when the output at pin 4 is low, the red
LED is off and the green LED is on, which can indicate there is no
fault present. However, when the output at pin 4 is high, the red
LED is on and the green LED is off, which can indicate that there
is a fault in the TE management unit 10. Similarly, for the second
alarm output, the red LED is connected to the latch U23 at pin 5
and the green LED, at connection 458, is connected to pin 5 via an
inverter G2 and a resistor R174; for the third alarm output, the
red LED is connected to the latch U23 at pin 6 and the green LED,
at connection 462, is connected to pin 6 via an inverter G3 and a
resistor R175; and for the fourth alarm output, the red LED is
connected to the latch U23 at pin 7 and the green LED, at
connection 466, is connected to pin 7 via an inverter G4 and a
resistor R176. The resistors R173-176 each can have a resistance of
about 470 ohms.
[0132] The latch U23 can also output signals to communicate alarm
outputs with a remote device (not shown). For example, pin 9 can be
connected to the remote device at connections 468, 470, and 472 via
the circuit including resistor R177 (e.g., 470 ohms), diode D33,
transistor Q35, reference voltage V15 and signal relay U24. The
signal relay U24 can have both normally open and normally closed
contacts, allowing alarm outputs to be communicated to the remote
device in a zero potential circuit.
[0133] The latch U23 can be an 8-bit addressable latch, such as
Part No. 74HC259, manufactured by Philips Semiconductors. Address
inputs to pins 1, 2, and 3 can be from input voltages V23, V24, and
V25, respectively, from the microcontroller circuit 410. An enable
input to pin 14 can be from input voltage V26 from the
microcontroller circuit 410. Pin 15 can be a conditional reset
input, which is active when low, and can be connected to voltage
V15. Pin 13 can receive input data from the microcontroller circuit
410 via an input voltage V27. The output voltages at pins 10, 11,
and 12 (voltages V28, V29 and V30, respectively) can be routed to
the tachometer circuit 402 via the connections 446, 448, and
450.
[0134] FIG. 20F illustrates the memory/external ports circuit 406
of the control circuit 361. The memory/external ports circuit 406
can include a serial port at connections 474, 476, 478 and 480,
which can allow RS-232 communication between the microcontroller
circuit 410 and an outside source (e.g., an external computer) for
automated test functions, data logging, etc. The connection 476 can
receive signals from the microcontroller circuit 410 via a
connection 482 through resistor R180 (e.g., 1 kilo-ohm) and the
connection 478 can transmit signals to the microcontroller circuit
410 via a connection 484 through resistor R181 (e.g., 1 kilo-ohm).
The connection 474 can supply power to the outside source, via the
voltage V14, and the connection 480 can be ground connection for
the outside source. The outside source can command the controller
38 via the serial port to run in a manual mode and begin automated
testing. The outside source can further command the controller 38
back into normal mode to continue normal operation after, or
during, testing. For example, the outside source can manually
override control temperatures to force the TE management unit 10 to
run in a certain test state. The outside source can send a request
to receive all controller data during or after the test. The
controller data from past operations can be collected and/or data
can be collected in near real-time. The controller data can be
processed by the outside source to determine the results of the
test. If, while connected to the outside source and a command is
not received for a time period, such as 15 seconds, the controller
38 can revert back to normal mode.
[0135] The memory/external ports circuit 406 can also include a
memory chip U25 and connection port J4. The memory chip U25 can be
a SEEPROM (serial EEPROM) chip. The connection port J4 can be used
to connect an external device, such as a display board. "I2C"
communications can be used for communication between the
microcontroller circuit 410, the memory chip U25, and the
connection port J4 via connections 486 and 488. For example, I2C
communications can be used with the memory chip U25 for loading and
storing controller runtime variables and logging faults. In some
embodiments, connection 488 can be the data line and connection 486
can be the clock line. Also, resistors R178 and R179 (both about 1
kilo-ohm) can be included in the memory/external ports circuit 406,
connecting voltage V14 to connections 486 and 488, respectively. In
addition, when not connected to an external device, the connection
port J4 can be connected to voltages V14 and V15 with filtering
capacitors C88-C93. The capacitors C88, C89, C91, and C92 each can
have a capacitance of about 1 microfarad and the capacitors C90 and
C93 each can have a capacitance of about 10 microfarads, rated for
16 volts.
[0136] The memory/external ports circuit 406 can further include a
connection port (including connections 490, 492, 494, and 496) for
remote devices, such as slave units. For example, input to the
remote unit, at the connection 494, can come from the
microcontroller circuit 410 via a connection 498. Output from the
remote unit, at the connection 492, can be routed to the
microcontroller circuit 410 via a connection 500. A pull-up
voltage, such as voltage V14 can be connected to the remote unit at
the connection 490, and a return from the remote unit, at the
connection 496, can lead to ground. The connection port can include
resistors R182 (e.g., 100 kilo-ohms), R183 (e.g., 1 kilo-ohm), R184
(e.g., 1 kilo-ohm), and capacitor C94 (e.g., 0.1 microfarads).
[0137] FIG. 20G illustrates the programming interface 408 of the
control circuit 361. The programming interface 408 can include a
reprogramming port J5 to allow reprogramming of a microcontroller
U26 (illustrated in FIG. 20I) within the microcontroller circuit
410 once the TE management unit 10 is already installed. Five pins
of the reprogramming port J5 can be connected to the
microcontroller circuit 410 via connections 502, 504, 506, 508, and
510, three pins be connection to ground, and two pins can be
connected to voltage source V14. One of the two pins connected to
the voltage source V14 is connected via a resistor R185 (e.g.,
about 47.5 kilo-ohms).
[0138] FIG. 20H illustrates the SS relay drive 409 of the control
circuit 361. The SS relay drive 409 can power external circuits
(not shown) with a solid state relay mechanism including a
transistor Q36 (e.g., Part No. MJD112, manufactured by Fairchild
Semiconductor.RTM., among others) and a resistor R186 (e.g., about
470 ohms). The SS relay drive 409 can receive signals from the
microcontroller circuit 410 via a connection 512. The base of the
transistor Q36 can be connected to the resistor R186 and the
emitter of the transistor Q36 can be connected to ground. When a
signal from the connection 512 applies a substantial cut-in voltage
across the base-emitter junction, the transistor Q36 becomes active
and allows current flow from the collector to the emitter. The
current flow can provide a path for a return connection 514 from
the external circuit through the collector and the emitter to
ground. With the active return current path to ground, the external
circuit can be powered by voltage V15 via a connection 516. Without
the signal from the microcontroller circuit 410 at the connection
512, the external circuit can remain without power (i.e., switched
off). In some embodiments, the external circuit can be a heater or
relay.
[0139] FIG. 20I illustrates the microcontroller circuit 410 of the
control circuit 361. The microcontroller circuit 410 can
incorporate the microcontroller U26, which can include a
microprocessor and/or a digital signal processor, a
digital-to-analog converter and an analog-to-digital converter. In
some embodiments, the microcontroller U26 can be a digital signal
controller, such as Part No. MC56F8025, manufactured by Freescale
Semiconductor.RTM.. The following paragraphs describe pin
assignments for the microcontroller U26 according to one embodiment
of the invention.
[0140] The connection 482, which is the receiving line of the
serial port in the memory/external ports circuit 406, can be
connected to pin 1 of the microcontroller U26. The connection 488,
which is the data line of the I2C bus line to the memory/external
ports circuit 406, can be connected to pin 2 of the microcontroller
U26. The connection 484, which is the transmission line of the
serial port in the memory/external ports circuit 406, can be
connected to pin 3 of the microcontroller U26. Pin 4 of the
microcontroller U26 can output voltage V25, which can transmitted
to the latch U23 in the alarm circuit 404. Pin 5 of the
microcontroller U26 can receive voltage V22, which is the output
from the multiplexer U22 in the tachometer circuit 402. The
connection 498, which is input line to the remote unit in the
memory/external ports circuit 406 can be connected to pin 6 of the
microcontroller U26. The connection 420, which is an input from the
sensor S9 of the temperature sensors circuit 398, can be connected
to pin 7 of the microcontroller U26. Pins 8, 9, 10, 37, and 38 of
the microcontroller U26 can be open. Pins 11, 29, 35, 16, 23, and
12, 17, 28, and 36 of the microcontroller U10 can be connected to a
capacitor circuit including capacitors C95-C99 in connection with
the voltage V14 (pins 11, 29, 35, 16, and 23) and ground (pins 12,
17, 28, and 36), with the configuration shown in FIG. 20I. The
capacitors C95 and C97 can each have a capacitance of about 1
microfarad, the capacitors C96 and C98 can each have a capacitance
of about 0.1 microfarads, and the capacitor C99 can have a
capacitance of about 10 microfarads.
[0141] The connection 418, which is an input from the temperature
sensor S8, can be connected to pin 13 of the microcontroller U26.
The connection 416, which is an input from the temperature sensor
S7, can be connected to pin 14 of the microcontroller U26. The
connection 414, which is an input from the temperature sensor S6,
can be connected to pin 15 of the microcontroller U26. The
connection 412, which is an input from the temperature sensor S5,
can be connected to pin 16 of the microcontroller U26. The
connection 504 from the programming interface 408 can be connected
to pin 19 of the microcontroller U26. Pin 20 of the microcontroller
U26 can output voltage V26, which can transmitted to the latch U23
in the alarm circuit 404. The connection 510 from the programming
interface 408 can be connected to pin 21 of the microcontroller
U26. Pins 22, 23, 24, 27, and 31 of the microcontroller U26 can
output the voltages V24, V23, V17, V18, and V19, respectively,
which can all be transmitted to the power circuit 360.
[0142] Pin 25 of the microcontroller U26 can output voltage V27,
which can be transmitted to the latch U23 in the alarm circuit 404.
The connection 500, which is input from to the remote unit in the
memory/external ports circuit 406 can be connected to pin 26 of the
microcontroller U26. The connection 486, which is the clock line of
the I2C bus line to the memory/external ports circuit 406, can be
connected to pin 30 of the microcontroller U26. The connections
430, 432, 434, and 436 from the fan speed control circuit 400 can
be connected to pins 40, 39, 32, and 33, respectively, of the
microcontroller U26. The connections 508, 502, and 506 from the
programming interface 408 can be connected to pins 41, 43, and 44,
respectively, of the microcontroller U26. In addition, the
connection 512 from the SS Relay Drive 409 can be connected to pin
42 of the microcontroller U26.
[0143] It will be appreciated by those skilled in the art that
while the invention has been described above in connection with
particular embodiments and examples, the invention is not
necessarily so limited, and that numerous other embodiments,
examples, uses, modifications and departures from the embodiments,
examples and uses are intended to be encompassed by the claims
attached hereto. The entire disclosure of each patent and
publication cited herein is incorporated by reference, as if each
such patent or publication were individually incorporated by
reference herein. Various features and advantages of the invention
are set forth in the following claims.
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