U.S. patent application number 15/424352 was filed with the patent office on 2017-08-24 for compressor capacity modulation system for multiple compressors.
This patent application is currently assigned to Emerson Climate Technologies, Inc.. The applicant listed for this patent is Emerson Climate Technologies, Inc.. Invention is credited to Jacob A. GROSHEK.
Application Number | 20170241690 15/424352 |
Document ID | / |
Family ID | 59626304 |
Filed Date | 2017-08-24 |
United States Patent
Application |
20170241690 |
Kind Code |
A1 |
GROSHEK; Jacob A. |
August 24, 2017 |
Compressor Capacity Modulation System For Multiple Compressors
Abstract
A system includes a plurality of compressors, an evaporator, an
expansion device, and a system controller. The compressors may be
linked in parallel. The system controller may: determine a
saturated evaporator temperature, a saturated condensing
temperature, and a target capacity demand; determine an estimated
system capacity and an estimated power consumption for each
compressor operating configuration; compare the estimated system
capacity with the target capacity demand and an error tolerance
value; select an optimum operating mode based on the comparisons
and based on the estimated power consumption; and command
activation and deactivation of the plurality of compressors to
achieve the selected optimum operating mode. The optimum operating
mode may be selected after the normal system logic achieves a
steady state and may be selected from a group having the estimated
system capacity within the error tolerance of the target capacity
demand and a lowest associated power consumption value.
Inventors: |
GROSHEK; Jacob A.; (Sidney,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Emerson Climate Technologies, Inc. |
Sidney |
OH |
US |
|
|
Assignee: |
Emerson Climate Technologies,
Inc.
Sidney
OH
|
Family ID: |
59626304 |
Appl. No.: |
15/424352 |
Filed: |
February 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62297680 |
Feb 19, 2016 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 28/08 20130101;
F25B 1/10 20130101; F25B 2700/2117 20130101; F25B 2400/0751
20130101; F04C 29/0085 20130101; F25B 2700/151 20130101; F25B
2700/197 20130101; F04C 23/001 20130101; F04C 28/02 20130101; F25B
2600/0251 20130101; F25B 2700/21152 20130101; F25B 2700/21151
20130101; F25B 2500/19 20130101; F25B 2700/1931 20130101; F25B
2700/195 20130101; F25B 49/022 20130101; F25B 2700/1933 20130101;
F04C 28/18 20130101; F04C 18/0215 20130101; F25B 2600/0253
20130101; F04C 28/28 20130101; F25B 2400/061 20130101; F25B
2700/2116 20130101; F04C 28/26 20130101 |
International
Class: |
F25B 49/02 20060101
F25B049/02; F04C 28/08 20060101 F04C028/08; F04C 28/18 20060101
F04C028/18; F25B 1/10 20060101 F25B001/10; F04C 23/00 20060101
F04C023/00; F04C 29/00 20060101 F04C029/00; F04C 28/02 20060101
F04C028/02; F04C 18/02 20060101 F04C018/02; F04C 28/28 20060101
F04C028/28 |
Claims
1. A system comprising: a plurality of compressors linked in
parallel by a common discharge line and a common suction line; an
evaporator; a condenser; and a system controller that determines a
saturated evaporator temperature of the evaporator, a saturated
condensing temperature of the condenser, a target capacity demand
for the plurality of compressors, and an estimated system capacity
and an estimated power consumption for each operating configuration
of the plurality of compressors based on the saturated evaporator
temperature and the saturated condensing temperature; wherein the
system controller compares the estimated system capacity for each
operating configuration with the target capacity demand and an
error tolerance value and selects an optimum operating mode of the
plurality of compressors based on the comparisons and the estimated
power consumption for each operating configuration, the optimum
operating mode being selected from a group of operating
configurations having the estimated system capacity within the
error tolerance of the target capacity demand and the optimum
operating mode having a lowest associated power consumption value
in the group; and wherein the system controller commands activation
and deactivation of the plurality of compressors to achieve the
selected optimum operating mode.
2. The system of claim 1, wherein the plurality of compressors
includes at least one fixed capacity compressor and at least one
two-stage compressor.
3. The system of claim 2, wherein the at least one two-stage
compressor includes a compressor having a delayed suction
system.
4. The system of claim 2, wherein the at least one two-stage
compressor includes a compressor having a variable speed motor.
5. The system of claim 2, wherein the at least one two-stage
compressor includes a compressor having a scroll separation
system.
6. The system of claim 1, wherein the plurality of compressors
includes a variable volume ratio compressor.
7. The system of claim 1, wherein the estimated system capacity is
calculated based on characteristics of each of the plurality of
compressors.
8. The system of claim 1, wherein the operating configuration for
the plurality of compressors includes a location of each of the
plurality of compressors and a coefficient performance curve for
each of the plurality of compressors.
9. The system of claim 1, wherein the system controller determines
the estimated power consumption for each operating configuration
based on a ten coefficient performance curve for each of the
plurality of compressors in the associated operating
configuration.
10. The system of claim 1, wherein the system controller determines
the estimated system capacity for each operating configuration
based on a ten coefficient performance curve for each of the
plurality of compressors in the associated operating
configuration.
11. The system of claim 1, wherein the system controller determines
whether the plurality of compressors have stabilized before
selecting the optimum operating mode, the determination of whether
the plurality of compressors have stabilized being based on an
output of at least one of a current sensor, a common suction line
temperature sensor, a common discharge line temperature sensor, a
common suction line pressure sensor, and a common discharge line
pressure sensor.
12. The system of claim 1, wherein the plurality of compressors
includes two fixed capacity compressors having different capacities
and one two-stage compressor, and has eleven associated operating
configurations.
13. The system of claim 1, wherein the plurality of compressors
includes two fixed capacity compressors and one two-stage
compressor with different capacities, and has seven associated
operating configurations.
14. A system comprising: a first circuit having a first plurality
of compressors linked in parallel by a first common discharge line
and a first common suction line; a second circuit having a second
plurality of compressors linked in parallel by a second common
discharge line and a second common suction line; and a system
controller that determines an estimated system capacity and an
estimated power consumption for each operating configuration of the
plurality of compressors in the first circuit and the plurality of
compressors in the second circuit based on a saturated evaporator
temperature and a saturated condensing temperature; wherein the
system controller selects an optimum operating mode of the
plurality of compressors in the first circuit and the plurality of
compressors in the second circuit based on a comparison of the
estimated system capacity for each operating configuration with a
target capacity demand and an error tolerance value and based on
the estimated power consumption for each operating configuration,
the optimum operating mode being selected from a group of operating
configurations having the estimated system capacity within the
error tolerance of the target capacity demand and the optimum
operating mode having a lowest associated power consumption value
in the group; and wherein the system controller commands activation
and deactivation of the plurality of compressors in the first
circuit and the plurality of compressors in the second circuit to
achieve the selected optimum operating mode.
15. A method for operating a system comprising: determining a
saturated evaporator temperature of the evaporator, a saturated
condensing temperature of the condenser, and a target capacity
demand for a plurality of compressors; determining an estimated
system capacity and an estimated power consumption for each
operating configuration of the plurality of compressors based on
the saturated evaporator temperature and the saturated condensing
temperature; comparing the estimated system capacity for each
operating configuration with the target capacity demand and an
error tolerance value; selecting an optimum operating mode of the
plurality of compressors based on the comparisons and based on the
estimated power consumption for each operating configuration, the
optimum operating mode being selected from a group of operating
configurations having the estimated system capacity within the
error tolerance of the target capacity demand and the optimum
operating mode having a lowest associated power consumption value
in the group; and commanding activation and deactivation of the
plurality of compressors to achieve the selected optimum operating
mode.
16. The method of claim 15, wherein the plurality of compressors
includes at least one of a fixed capacity compressor, a two-stage
compressor, and a variable volume ratio compressor, wherein if the
plurality of compressors includes the two-stage compressor, the
two-stage compressor includes at least one of a compressor having a
delayed suction system, a compressor having a variable speed motor,
and a compressor having a scroll separation system.
17. The method of claim 15, further comprising calculating the
estimated system capacity based on the operating configuration for
the plurality of compressors.
18. The method of claim 17, wherein the operating configuration for
the plurality of compressors includes a location of each of the
plurality of compressors and a ten coefficient performance curve
for each of the plurality of compressors.
19. The method of claim 15, further comprising determining the
estimated power consumption for each operating configuration based
on a ten coefficient performance curve for each of the plurality of
compressors in the associated operating configuration.
20. The method of claim 15, further comprising determining the
estimated system capacity for each operating configuration based on
a ten coefficient performance curve for each of the plurality of
compressors in the associated operating configuration.
21. The method of claim 15, further comprising determining whether
the plurality of compressors have stabilized before selecting the
optimum operating mode, the determination of whether the plurality
of compressors have stabilized being based on an output of at least
one of a current sensor, a common suction line temperature sensor,
a common discharge line temperature sensor, a common suction line
pressure sensor, and a common discharge line pressure sensor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/297,680, filed on Feb. 19, 2016. The entire
disclosure of the above application is incorporated herein by
reference.
FIELD
[0002] The present disclosure relates to a compressor capacity
modulation system and, more particularly, to a compressor capacity
modulation system for multiple compressors that optimizes overall
system efficiency.
BACKGROUND
[0003] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0004] Compressors are used in a wide variety of industrial and
residential applications to circulate refrigerant within a
refrigeration, heat pump, HVAC, or chiller system (generically
referred to as "refrigeration systems") to provide a desired
heating and/or cooling effect. In any of the foregoing systems, the
compressor should provide consistent and efficient operation to
ensure that the particular refrigeration system functions
properly.
[0005] Compressor systems may include multiple fixed compressors
connected together for increased efficiency and capacity
modulation. The compressors have the capability to operate together
or individually, delivering several discrete capacity steps as
needed. System capacity can be modulated by using multiple
refrigeration circuits or by using multiple compressors in a
single-circuit. For example, in a four compressor system,
frequently used in packaged rooftops, individual compressors can be
turned on and off to achieve a specific output. In other examples,
such as for chillers, two to eight compressors is the typical
number per unit, which means, depending on the even or uneven
combinations, up to 12 capacity steps are available to match the
load by cycling the compressors on and off.
[0006] The multiple fixed compressors are started and shut down in
the order in which they are connected to meet capacity demands for
the system. The multiple fixed compressors may also be started in
the order of least to most run time. The compressors run until a
temperature (or other) threshold is met. Based on the temperature's
position relative to the threshold, the last compressor is turned
on and off to modulate system capacity. Current multiple compressor
systems are focused on meeting capacity needs and can tend to cycle
unnecessarily, often overlooking more efficient operating
modes.
SUMMARY
[0007] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0008] An example system includes a plurality of compressors, an
evaporator, a condenser, and a system controller. The plurality of
compressors may be linked in parallel by a common discharge line
and a common suction line. The system controller may determine a
saturated evaporator temperature of the evaporator, a saturated
condensing temperature of the condenser, and a target capacity
demand for the plurality of compressors. The system controller may
determine an estimated system capacity and an estimated power
consumption for each operating configuration of the plurality of
compressors based on the saturated evaporator temperature and the
saturated condensing temperature. The system controller may compare
the estimated system capacity for each operating configuration with
the target capacity demand and an error tolerance value. The system
controller may select an optimum operating mode of the plurality of
compressors based on the comparisons and based on the estimated
power consumption for each operating configuration. The optimum
operating mode may be selected from a group of operating
configurations having the estimated system capacity within the
error tolerance of the target capacity demand and the optimum
operating mode having a lowest associated power consumption value
in the group. The system controller may command activation and
deactivation of the plurality of compressors to achieve the
selected optimum operating mode.
[0009] The compressor system may further include a plurality of
compressors having at least one fixed capacity compressor and at
least one two-stage compressor.
[0010] The compressor system may further include at least one
two-stage compressor having a compressor with a delayed suction
system.
[0011] The compressor system may further include at least one
two-stage compressor having a compressor with a variable speed
motor.
[0012] The compressor system may further include a plurality of
compressors having a variable volume ratio compressor.
[0013] The compressor system may further include at least one
two-stage compressor having a compressor with another capacity
modulation scheme or a scroll separation system.
[0014] The compressor system may further include an estimated
system capacity that is calculated based on characteristics of each
of the plurality of compressors.
[0015] The compressor system may further include an operating
configuration for the plurality of compressors having a location of
each of the plurality of compressors and a coefficient performance
curve for each of the plurality of compressors.
[0016] The compressor system may further include a system
controller that determines the estimated power consumption for each
operating configuration based on a ten coefficient performance
curve for each of the plurality of compressors in the associated
operating configuration.
[0017] The compressor system may further include a system
controller that determines the estimated system capacity for each
operating configuration based on a ten coefficient performance
curve for each of the plurality of compressors in the associated
operating configuration.
[0018] The compressor system may further include a system
controller that determines whether the plurality of compressors
have stabilized before selecting the optimum operating mode. The
determination of whether the plurality of compressors have
stabilized may be based on an output of at least one of a current
sensor, a common suction line temperature sensor, a common
discharge line temperature sensor, a common suction line pressure
sensor, and a common discharge line pressure sensor.
[0019] The compressor system may further include a plurality of
compressors having two fixed capacity compressors with different
capacities and one two-stage compressor, and having eleven
associated operating configurations.
[0020] The compressor system may further include a plurality of
compressors having two fixed capacity compressors and one two-stage
compressor with different capacities, and having seven associated
operating configurations.
[0021] An example system includes a first circuit, a second
circuit, and a system controller. The first circuit has a first
plurality of compressors linked in parallel by a first common
discharge line and a first common suction line. The second circuit
has a second plurality of compressors linked in parallel by a
second common discharge line and a second common suction line. The
system controller determines an estimated system capacity and an
estimated power consumption for each operating configuration of the
plurality of compressors in the first circuit and the plurality of
compressors in the second circuit based on a saturated evaporator
temperature and a saturated condensing temperature. The system
controller selects an optimum operating mode of the plurality of
compressors in the first circuit and the plurality of compressors
in the second circuit based on a comparison of the estimated system
capacity for each operating configuration with a target capacity
demand and an error tolerance value and based on the estimated
power consumption for each operating configuration. The optimum
operating mode is selected from a group of operating configurations
that have the estimated system capacity within the error tolerance
of the target capacity demand and the optimum operating mode has a
lowest associated power consumption value in the group. The system
controller commands activation and deactivation of the plurality of
compressors in the first circuit and the plurality of compressors
in the second circuit to achieve the selected optimum operating
mode. It should be understood that the system is not limited to two
circuits but can control and optimize the compressor operating
modes in any number of circuits.
[0022] An example method for operating a system may include
determining a saturated evaporator temperature of the evaporator, a
saturated condensing temperature of the condenser, and a target
capacity demand for a plurality of compressors; determining an
estimated system capacity and an estimated power consumption for
each operating configuration of the plurality of compressors based
on the saturated evaporator temperature and the saturated
condensing temperature; comparing the estimated system capacity for
each operating configuration with the target capacity demand and an
error tolerance value; selecting an optimum operating mode of the
plurality of compressors based on the comparisons and based on the
estimated power consumption for each operating configuration, the
optimum operating mode being selected from a group of operating
configurations having the estimated system capacity within the
error tolerance of the target capacity demand and the optimum
operating mode having a lowest associated power consumption value
in the group; and commanding activation and deactivation of the
plurality of compressors to achieve the selected optimum operating
mode.
[0023] The method may further include a plurality of compressors
including at least one of a fixed capacity compressor, a two-stage
compressor, and a variable volume ratio compressor, wherein if the
plurality of compressors includes the two-stage compressor, the
two-stage compressor includes at least one of a compressor having a
delayed suction system, a compressor having a variable speed motor,
and a compressor having a scroll separation system.
[0024] The method may further include calculating the estimated
system capacity based on the operating configuration for the
plurality of compressors.
[0025] The method may further include an operating configuration
for the plurality of compressors having a location of each of the
plurality of compressors and a ten coefficient performance curve
for each of the plurality of compressors.
[0026] The method may further include determining the estimated
power consumption for each operating configuration based on a ten
coefficient performance curve for each of the plurality of
compressors in the associated operating configuration.
[0027] The method may further include determining the estimated
system capacity for each operating configuration based on a ten
coefficient performance curve for each of the plurality of
compressors in the associated operating configuration.
[0028] The method may further include determining whether the
plurality of compressors have stabilized before selecting the
optimum operating mode, the determination of whether the plurality
of compressors have stabilized being based on an output of at least
one of a current sensor, a common suction line temperature sensor,
a common discharge line temperature sensor, a common suction line
pressure sensor, and a common discharge line pressure sensor.
[0029] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
DRAWINGS
[0030] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0031] FIG. 1 is a schematic of a compressor system according to
the present disclosure;
[0032] FIG. 2 is a perspective view of multiple compressors of the
compressor system of FIG. 1;
[0033] FIG. 3 is a chart illustrating a number of operating modes
for a variety of compressor systems;
[0034] FIG. 4 is a table illustrating the possible operating modes
for an uneven trio compressor system;
[0035] FIG. 5 is a schematic of a control system for the compressor
system of FIG. 1;
[0036] FIG. 6 is an example pressure-temperature chart for a
compressor;
[0037] FIG. 7 is a flow chart illustrating the steps for operating
the compressor system of FIG. 1; and
[0038] FIG. 8 is a graph illustrating the efficiency impact of an
optimized fixed pressure ratio versus a traditional fixed pressure
ratio versus a variable valve ratio compressor system.
[0039] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0040] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0041] With reference to FIG. 1, a compressor capacity modulation
system 10 is provided. The compressor capacity modulation system 10
may be used in conjunction with a heating, ventilation, and air
conditioning (HVAC) system or refrigeration system 12 including at
least multi-linked, or multi-connected, compressors 14, a condenser
18, and an evaporator 22. While the refrigeration system 12 is
described and shown as including multi-linked compressors 14, the
condenser 18, and the evaporator 22, the refrigeration system 12
may include additional and/or alternative components (for example
only, an expansion valve). Further, the present disclosure is
applicable to various types of refrigeration systems including, but
not limited to, heating, ventilating, air conditioning (HVAC), heat
pump, refrigeration, and chiller systems.
[0042] During operation of the refrigeration system 12, the
multi-linked compressors 14 circulate refrigerant generally between
the condenser 18 and the evaporator 22 to produce a desired heating
and/or cooling effect. Specifically, the multi-linked compressors
14 receive refrigerant in vapor form and compress the refrigerant.
The multi-linked compressors 14 provide pressurized refrigerant in
vapor form to the condenser 18.
[0043] All or a portion of the pressurized refrigerant received
from the multi-linked compressors 14 may be converted into a liquid
state within the condenser 18. Specifically, the condenser 18
transfers heat from the refrigerant to the surrounding air, thereby
cooling the refrigerant. When the refrigerant vapor is cooled to a
temperature that is less than a saturation temperature, the
refrigerant changes state from a vapor to a liquid. The condenser
18 may include a condenser fan (not illustrated) that increases the
rate of heat transfer away from the refrigerant by forcing air
across a heat-exchanger coil associated with the condenser 18.
[0044] The refrigerant may pass through an expansion valve (not
illustrated) that expands the refrigerant prior to reaching the
evaporator 22. The evaporator 22 may receive a mixture of vapor
refrigerant and liquid refrigerant or purely liquid refrigerant
from the condenser 18. The refrigerant absorbs heat in the
evaporator 22. Accordingly, liquid refrigerant disposed within the
evaporator 22 changes state from a liquid to a vapor when warmed to
a temperature that is greater than or equal to the saturation
temperature of the refrigerant. The evaporator 22 may include an
evaporator fan (not illustrated) that increases the rate of heat
transfer to the refrigerant by forcing air across a heat-exchanger
coil associated with the evaporator 22.
[0045] As the liquid refrigerant absorbs heat, the ambient air
disposed proximate to the evaporator 22 is cooled. The evaporator
22 may be disposed within a space to be cooled such as a building
or refrigerated case where the cooling effect produced by the
refrigerant absorbing heat is used to cool the space. The
evaporator 22 may also be associated with a heat-pump refrigeration
system where the evaporator 22 may be located remotely from the
building such that the cooling effect is lost to the atmosphere and
the rejected heat generated by the condenser 18 is directed to the
interior of a space to be heated.
[0046] Referring additionally to FIG. 2, the multi-linked
compressors 14 may further include two or more compressors 26, 30,
34 connected in parallel. Each of the compressors 26, 30, 34 of the
multi-linked compressors 14 includes a plurality of solenoids 36
and contactors 38 that can be activated to control the compressor.
For example only, the solenoids 36 and contactors 38 may be
activated to run the compressor at full capacity or load or at a
part capacity or load, where applicable. For example only, three
compressors 26, 30, 34 are illustrated in FIGS. 1 and 2. While
three compressors are illustrated and described, it is understood
that any number of compressors may be included in the multi-linked
compressors 14, including two compressors and more than three
compressors. The compressors 26, 30, 34 share a single suction
header or common suction line 40 and a single discharge header or
common discharge line 42.
[0047] While a single circuit of multi-linked compressors is
discussed and illustrated, it is understood that there may be
multiple circuits in a single system. Each circuit in the system
includes its own multi-linked compressors linked in tandem, trio,
quad, or any other number. The circuits in a multi circuit system
are independent but may run through a common evaporator and a
common condenser. The output may be modulated by turning on the
individual circuits separately or in combination with other
circuits. Thus, the present disclosure is not limited to a single
circuit of multi-linked compressors, but may be applied across any
number of multiple circuits, each having multi-linked
compressors.
[0048] The multi-linked compressors 14 may include one or more
multi-stage compressors that are operable at multiple different
capacity levels. For example, a two-stage compressor operable at
full capacity or load (or full scroll volume ratio) and at
modulated capacity or load (with a lower scroll volume ratio) can
be used. The multi-stage compressor may utilize any manner of
capacity modulation, including, but not limited to two-step
capacity modulation or continuous capacity modulation. Two-step
capacity modulation is where the compressor runs at either a full
capacity or load (for example, 100% capacity) or a part capacity or
load (for example, 67% capacity), depending on cooling and/or
heating demand. For example, two-step capacity modulation may be
accomplished with a delayed suction system that modulates
compressor capacity by venting an intermediate pressurized chamber
to the suction chamber, as described in U.S. Pat. No. 6,821,092,
the disclosure of which is incorporated herein by reference. With
continuous capacity modulation, or variable valve modulation, the
capacity of the compressor can be modulated from 10-100 percent so
that the output precisely matches the changing cooling requirements
of the space. For example, a bypass valve and passage can be used
to continuously modulate compressor capacity, without changing the
speed of the motor. For further example, continuous capacity
modulation can be accomplished with a variable speed capacity
modulation system that varies the speed of the compressor motor.
The compressor motor speed determines the rate of refrigerant flow;
thus, by varying the motor frequency, capacity can be modulated.
Therefore, with a variable speed capacity modulation system,
capacity output increases and decreases with motor speed. For
further example, continuous capacity modulation can be accomplished
with a scroll separation capacity modulation system. In a scroll
separation capacity modulation system, capacity control is achieved
by separating the scroll sets axially over a small period of time.
For example, a scroll separation capacity modulation system is
described in U.S. Pat. No. 6,213,731, which is incorporated herein
by reference. In addition, any of the continuous capacity modulated
systems can also be operated in two discrete capacity steps to
accomplish two-step capacity modulation. A two-stage compressor,
because of its capacity modulation, has three different operating,
or power, modes: off, full capacity or load, and modulated, or
reduced, capacity or load.
[0049] The multi-linked compressors 14 may include fixed capacity
compressors. A fixed capacity compressor is a compressor having a
traditional scroll design with a single, standard built-in volume
ration (BIVR). The fixed capacity compressor has two different
operating, or power, modes: off and full capacity or load.
[0050] The multi-linked compressors 14 may include variable volume
ratio compressors. A variable volume ratio compressor incorporates
a bypass passage to eliminate over compression losses by porting
compressed fluid though a bypass valve in a fixed scroll of the
compressor. The variable volume ratio compressor has three
different operating, or power, modes: off, full BIVR and capacity,
and reduced scroll volume ratio. The variable volume ratio
compressor may be a passive scheme or any other scheme. While the
variable volume ratio compressor may be a passive scheme in terms
of control, the variable volume ratio compressor adds additional
complexity by adapting scroll volume ratio to meet needs. In
multi-linked compressors, knowing which compressors have variable
volume ratio designs and selectively turning them on and off can
influence the overall system efficiency (see FIG. 8, discussed in
further detail below). Variable volume ratio compressors may offer
higher efficiency over a larger range of system pressures, as
compared with a compressor having an optimized fixed pressure ratio
or a traditional fixed pressure ratio. The pressure ratio, as seen
in FIG. 8, is calculated as discharge pressure over suction
pressure.
[0051] The multi-linked compressors 14 may be compressors linked in
parallel in even multiples or uneven multiples. Even multiples are
parallel compressors of the same BIVR and capacity; whereas uneven
multiples are parallel compressors of different BIVR and/or
capacities. The multi-linked compressors 14 may also incorporate
one or more of the types of two-stage compressors, the fixed
capacity compressors, and variable volume ratio compressors.
[0052] Now referring to FIG. 3, in some embodiments, the
multi-linked compressors 14 may be an even tandem of fixed capacity
compressors, meaning that the multi-linked compressors 14 may
include two fixed capacity compressors having the same BIVR and
capacity being linked in parallel. Because of the two operating
modes for each of the two fixed capacity compressors, and the fact
that the two fixed capacity compressors have the same BIVR and
capacity, the even tandem of fixed capacity compressors has two
total possible operating, or power, modes, excluding the operating
mode where all compressors are off, i.e., the two operating, or
power, modes being: (1) one compressor on; and (2) two compressors
on.
[0053] In other embodiments, the multi-linked compressors 14 may be
an even trio of fixed capacity compressors meaning that the
multi-linked compressors 14 may include three fixed capacity
compressors having the same BIVR and capacity being linked in
parallel. Because of the two operating modes for each of the three
fixed capacity compressors, and the fact that the three fixed
capacity compressors have the same BIVR and capacity, the even trio
of fixed capacity compressors has three total possible operating,
or power, modes, excluding the operating mode where all compressors
are off, i.e., the three operating, or power modes, being: (1) one
compressor on; (2) two compressors on; and (3) three compressors
on.
[0054] In other embodiments, the multi-linked compressors 14 may be
an uneven tandem of fixed capacity compressors meaning that the
multi-linked compressors 14 may include two fixed capacity
compressors having different BIVR and capacities being linked in
parallel. Because of the two operating modes for each of the two
fixed capacity compressors, and the fact that the two fixed
capacity compressors have different BIVR and capacities, the uneven
tandem of fixed capacity compressors has three total possible
operating, or power, modes, excluding the operating mode where all
compressors are off, i.e., the three operating, or power, modes
being: (1) lower capacity compressor on; (2) higher capacity
compressor on; and (3) both compressors on.
[0055] In other embodiments, the multi-linked compressors 14 may be
an uneven trio of fixed capacity compressors meaning that the
multi-linked compressors 14 may include three fixed capacity
compressors having different BIVR and capacities being linked in
parallel. Because of the two operating modes for each of the three
fixed capacity compressors, and the fact that the three fixed
capacity compressors have different BIVR and capacities, the uneven
trio of fixed capacity compressors has seven total possible
operating, or power, modes, excluding the operating mode where all
compressors are off, i.e., the seven operating, or power, modes
being: (1) lowest capacity compressor on; (2) middle capacity
compressor on; (3) highest capacity compressor on; (4) lowest and
middle capacity compressors on; (5) lowest and highest capacity
compressors on; (6) middle and highest capacity compressors on; and
(7) all three compressors on.
[0056] In other embodiments, the multi-linked compressors 14 may be
an even tandem of two-stage compressors, meaning that the
multi-linked compressors 14 may include one two-stage compressor
and one fixed capacity compressor, with both compressors having the
same BIVR and capacity being linked in parallel. Because of the
three operating modes for the two-stage compressor and the two
operating modes for the fixed capacity compressor, and the fact
that the two-stage and the fixed capacity compressors have the same
BIVR and capacities, the even tandem of two-stage compressors has
four total possible operating, or power, modes, excluding the
operating mode where all compressors are off, i.e., the four
operating, or power, modes being: (1) fixed capacity compressor on
(or two-stage compressor on at high capacity); (2) two-stage
compressor on at low capacity; (3) fixed capacity compressor on and
two stage compressor on at low capacity; and (4) fixed capacity
compressor on and two stage compressor on at high capacity.
[0057] In other embodiments, the multi-linked compressors 14 may be
an even trio of two-stage compressors meaning that the multi-linked
compressors 14 may include one two-stage compressor and two fixed
capacity compressors having the same BIVR and capacity being linked
in parallel. Because of the three operating modes for the two-stage
compressor and the two operating modes for each of the fixed
capacity compressors, and the fact that the two-stage and fixed
capacity compressors have the same BIVR and capacity, the even trio
of two-stage compressors has six total possible operating, or
power, modes, excluding the operating mode where all compressors
are off, i.e., the six operating, or power, modes being: (1) either
fixed capacity compressor on (or two-stage compressor on at high
capacity); (2) two-stage compressor on at low capacity; (3) one
fixed capacity compressor on and two-stage compressor on at low
capacity; (4) two fixed capacity compressors on (or one fixed
capacity compressor and two-stage compressor on at high capacity);
(5) two fixed capacity compressors on and two-stage compressor on
at low capacity; and (6) two fixed capacity compressors on and
two-stage compressor on at high capacity.
[0058] In other embodiments, the multi-linked compressors 14 may be
an uneven tandem of two-stage compressors, meaning that the
multi-linked compressors 14 may include one two-stage compressor
and one fixed capacity compressor having different BIVR and
capacities being linked in parallel. Because of the three operating
modes for the two-stage compressor and the two operating modes for
the fixed capacity compressor, and the fact that the two-stage and
fixed capacity compressors have different BIVR and capacities, the
uneven tandem of two-stage compressors has five total possible
operating, or power, modes, excluding the operating mode where all
compressors are off, the five operating, or power, modes being: (1)
two-stage compressor on at low capacity; (2) fixed capacity
compressor on (3) two-stage compressor on at high capacity; (4)
fixed capacity compressor on and two-stage compressor on at low
capacity; and (5) fixed capacity compressor on and two-stage
compressor on at high capacity.
[0059] In other embodiments, the multi-linked compressors 14 may be
an uneven trio of two-stage compressors, meaning that the
multi-linked compressors 14 may include one two-stage compressor
and two fixed capacity compressors having different BIVR and
capacities being linked in parallel. Because of the three operating
modes for the two-stage compressor and the two operating modes for
each of the fixed capacity compressors, and the fact that the
two-stage and fixed capacity tech compressors have different BIVR
and capacities, the uneven trio of two-stage compressors has eleven
total possible operating, or power, modes, excluding the operating
mode where all compressors are off, the eleven operating, or power,
modes being: (1) lower capacity fixed compressor on; (2) higher
capacity fixed compressor on; (3) two-stage compressor on at low
capacity; (4) two-stage compressor on at high capacity; (5) lower
capacity fixed compressor on and higher capacity fixed compressor
on; (6) lower capacity fixed compressor on and two-stage compressor
on at low capacity; (7) lower capacity fixed compressor on and
two-stage compressor on at high capacity; (8) higher capacity fixed
compressor on and two-stage compressor on at low capacity; (9)
higher capacity fixed compressor on and two-stage compressor on at
high capacity; (10) lower capacity fixed compressor on, higher
capacity fixed compressor on, and two-stage compressor on at low
capacity; and (11) lower capacity fixed compressor on, higher
capacity fixed compressor on, and two-stage compressor on at high
capacity.
[0060] In other embodiments, the multi-linked compressors 14 may be
a trio of uneven two-stage compressors comprising three two-stage
compressors having different BIVR and capacities linked in
parallel. Because of the three operating modes for each of the
three two-stage compressors, and the fact that the two-stage
compressors have different BIVR and capacities, the trio of
two-stage compressors have twenty-six total possible operating, or
power, modes, excluding the operating mode where all compressors
are off, the twenty-six operating, or power, modes being: (1) lower
capacity two-stage compressor on at high capacity; (2) lower
capacity two-stage compressor on at low capacity; (3) middle
capacity two-stage compressor on at high capacity; (4) middle
capacity two-stage compressor on at low capacity; (5) higher
capacity two-stage compressor on at high capacity; (6) higher
capacity two-stage compressor on at low capacity; (7) lower and
middle capacity two-stage compressors on at high capacity; (8)
lower and middle capacity two-stage compressors on at low capacity;
(9) lower capacity two-stage compressor on at high capacity and
middle capacity two-stage compressors on at low capacity; (10)
lower capacity two-stage compressor on at low capacity and middle
capacity two-stage compressors on at high capacity; (11) lower and
higher capacity two-stage compressors on at high capacity; (12)
lower and higher capacity two-stage compressors on at low capacity;
(13) lower capacity two-stage compressor on at high capacity and
high capacity two-stage compressors on at low capacity; (14) lower
capacity two-stage compressor on at low capacity and high capacity
two-stage compressors on at high capacity (15) middle and higher
capacity two-stage compressors on at high capacity; (16) middle and
higher capacity two-stage compressors on at low capacity; (17)
middle capacity two-stage compressor on at high capacity and high
capacity two-stage compressors on at low capacity; (18) middle
capacity two-stage compressor on at low capacity and high capacity
two-stage compressors on at high capacity (19) lower, middle, and
higher capacity two-stage compressors on at high capacity; (20)
lower, middle, and higher capacity two-stage compressors on at low
capacity; (21) lower and middle capacity two-stage compressors on
at high capacity and higher capacity two-stage compressor on at low
capacity; (22) lower and higher capacity two-stage compressors on
at high capacity and middle capacity two-stage compressor on at low
capacity; (23) middle and higher capacity two-stage compressors on
at high capacity and lower capacity two-stage compressor on at low
capacity; (24) lower and middle capacity two-stage compressors on
at low capacity and higher capacity two-stage compressor on at high
capacity; (25) lower and higher capacity two-stage compressors on
at low capacity and middle capacity two-stage compressor on at high
capacity; and (26) middle and higher capacity two-stage compressors
on at low capacity and lower capacity two-stage compressor on a
high capacity.
[0061] Now referring to FIG. 4, the total possible operating modes
is determined based on the number of possible operating modes for
each of the compressors and whether the compressors have the same
or different BIVR and capacities. For example, the uneven trio of
two-stage compressors shown in FIG. 4 has one two-stage compressor
(for example, a two-stage compressor with a 83,000 BTU/hr capacity)
and two fixed capacity compressors with different BIVR and
capacities (for example, a fixed capacity compressor with a 76,000
BTU/hr capacity and a fixed capacity compressor with a 91,000
BTU/hr capacity) being linked in parallel. With this combination of
compressors, there are eleven total possible operating modes,
depicted by the eleven rows in FIG. 4. Each possible operating mode
is identified in FIG. 4. With reference to the Key, the two-stage
compressor has the possibility of being off (0), at a full BIVR and
capacity or load (1), or at a lower or modulated capacity or load
(-1). Each of the fixed capacity compressors has the possibility of
being off (0) or at full BIVR and capacity or load (1). Thus, the
different combinations of compressor on/off/modulated modes are
combined to make the total eleven possible operating modes,
excluding the operating mode where all compressors are off.
[0062] While the fixed capacity even tandem, fixed capacity even
trio, fixed capacity uneven tandem, fixed capacity uneven trio,
two-stage even tandem, two-stage even trio, two-stage uneven
tandem, and two-stage uneven trio are discussed above, it is
understood that any combination of two-stage, multi-stage, fixed
capacity, and variable valve compressors may be combined in
parallel for the multi-linked compressors 14. The total number of
possible operating modes for the multi-linked compressor 14 is
determined based on the number of possible operating modes for each
of the compressors and whether the compressors have the same or
different full BIVR and capacities.
[0063] Referring to FIGS. 1, 2, and 5, a system controller 46 may
be associated with the compressor capacity modulation system 10
and/or the multi-linked compressors 14 and may command start up,
stabilization, shut down, more capacity, and less capacity for each
of the multi-linked compressors 14 and/or the refrigeration system
12. The system controller 46 may utilize a series of sensors to
determine both measured and non-measured operating parameters of
the compressor 14 and/or the refrigeration system 12. While the
system controller 46 is shown as being associated with the
multi-linked compressors 14, the system controller 46 could be
located anywhere within or outside of the refrigeration system 12.
The system controller 46 may use the non-measured operating
parameters in conjunction with the measured operating parameters to
command start up, stabilization, shut down, more capacity, and less
capacity for each of the multi-linked compressors 14 and/or the
refrigeration system 12.
[0064] The system controller 46 may receive a common discharge line
temperature to determine stabilization of the compressors in the
multi-linked compressors 14, as further described below. The system
controller 46 may also communicate with various sensors to
determine a stabilization of the multi-linked compressors. For
example, stabilization may be determined from a current sensor 50
measuring motor current of each of the compressors in the
multi-linked compressors 14. Stabilization may also be determined
from a suction line temperature. A suction line temperature sensor
54 may be placed in the suction line into the multi-linked
compressors 14. The common discharge line temperature may be
directly sensed by a discharge line temperature sensor 58 from the
discharge line out of the multi-linked compressors 14 and the
system controller may look for the discharge line temperature
signal to steady out and/or a derivative of the signal to go to
zero. Similarly, when the stabilization of the multi-linked
compressors is determined from an output of the current sensor 50
or a suction line temperature sensor 54, the system controller 46
will look for the signal(s) to steady out and/or a derivative of
the signal(s) to go to zero.
[0065] The system controller 46 may also receive operating
conditions of the compressor, such as a saturated evaporator
temperature (Ts) and a saturated condensing temperature (Tc). The
saturated evaporator temperature and saturated condensing
temperature may be directly sensed from a temperature sensor 62 in
the evaporator 22 and a temperature sensor 66 in the condenser 18,
respectively. The saturated evaporator temperature and saturated
condensing temperature may also be determined from pressures sensed
from a pressure sensor 70 at the evaporator 22 and a pressure
sensor 74 at the condenser 18, respectively. The condensing
pressure sensed from the pressure sensor 74 is the pressure at
which the refrigerant is phase changing from a vapor to a liquid.
The evaporating pressure sensed from the pressure sensor 70 is the
pressure at which the refrigerant is phase changing from a liquid
to a vapor.
[0066] For example only, the saturated evaporator temperature may
be directly correlated to the saturated evaporator pressure and the
saturated condensing temperature may be directly correlated to the
saturated condensing pressure. An example chart correlating the
pressures with the temperatures for various refrigerant types is
provided at FIG. 6. Thus, the system controller 46 can determine
the saturated evaporator temperature and saturated condensing
temperature from looking up the sensed values in a table stored in
a memory 78 within the system controller 46.
[0067] The system controller 46 may further store in memory 78 a
ten-coefficient performance model for each of the multi-linked
compressors 14. The ten-coefficient performance model is determined
by the manufacturer or installer and describes the operating
characteristics for the compressor. The ten-coefficient performance
model may be entered into the memory 78 through a user interface 82
during installation or inspection or at the completion of
manufacture. The ten-coefficient performance model is compressor
model and size specific and is published by compressor
manufacturers. Compressor capacity can be calculated from the ARI
(Air-Conditioning and Refrigeration Institute, now the
Air-Conditioning, Heating, & Refrigeration Institute) ten
coefficient performance curve formula:
X=C0+(C1*S)+(C2*D)+(C3*S.sup.2)+(C4*S*D)+(C5*D.sup.2)+(C6*S.sup.3)+(C7*D-
*S.sup.2)+(C8*S*D.sup.2)+(C9*D.sup.3)
where X is capacity (BTU/HR) or Power (watts or amps), S is
saturated evaporating temperature, and D is saturated condensing
temperature.
[0068] While a ten-coefficient performance model is discussed, it
is understood that different coefficient characterizations may be
implemented. For example, the compressor may be modeled based on a
twenty-coefficient system. The present disclosure is not limited to
a ten-coefficient performance model, but may implement any
compressor characterization scheme such as a ten-coefficient
scheme, a twenty-coefficient scheme, or any other number of
coefficient schemes.
[0069] A position, or configuration, of each compressor in the
multi-linked compressors 14 is also stored in the memory 78. For
example, referring additionally to FIGS. 1, 2, and 4, if the
multi-linked compressors 14 are aligned in the order of two-stage
compressor, fixed capacity compressor 1, and fixed capacity
compressor 2, the two-stage compressor may be assigned the A
position, fixed capacity compressor 1 may be assigned the B
position, and fixed capacity compressor 2 may be assigned the C
position. Thus, the memory 78 stores the identity and location, or
configuration, of each compressor in the multi-liked compressors
14.
[0070] The system controller 46 receives inputs for, or calculates
from sensor data, common discharge line temperature, saturated
evaporator temperature, saturated condensing temperature, the ten
coefficient performance models or curves, and the identity and
position of each compressor in the multi-linked compressors 14.
From this data, the system controller 46 commands start up,
stabilization, shut down, more capacity, and less capacity for the
multi-linked compressors 14.
[0071] The system controller 46 may include processing circuitry 86
for carrying out the functions of a method 100 for modulating
compressor capacity. Now referring to FIGS. 5 and 7, the system
controller 46 receives a request for a target system capacity (or a
capacity demand) at step 104. For example, the target system
capacity may be calculated or determined based on a comparison of a
current temperature within an air-conditioned or refrigerated space
with a target temperature within the air-conditioned or
refrigerated space. For further example, the target system capacity
may be calculated or determined based on a current refrigerant
temperature or pressure as compared with a target refrigerant
temperature or pressure. The processing circuitry 86 may command a
startup of one or more of the compressors 26, 30, 34 in the
multi-linked compressors 14 at step 108 based on the capacity
demand or request for a target system capacity. Once the
compressors in the multi-linked compressors 14 are running, the
processing circuitry 86 may wait for and determine a stabilization
state of the activated compressor(s) 26, 30, 34 in the multi-linked
compressors 14 at step 112.
[0072] The stabilization/start state follows a prescribed starting
process which brings each of the compressors 26, 30, 34 in the
multi-linked compressors 14 on one at a time to limit inrush
current. For example, the largest capacity single compressor may be
started first. The remaining compressors may be started in order of
largest capacity to smallest capacity until the target system
capacity is met. The stabilization/start state of the multi-linked
compressors 14 starts with the first demand signal from the system
controller 46 and ends with steady state operation of the activated
compressors in the multi-linked compressors 14. Steady state
operation is determined by monitoring a derivative value of
discharge line temperature over time and watching for the
derivative value to approach a low value or threshold value for a
set period of time. For example only, a stability or steady state
operation may be determined where the derivative value (a discharge
line temperature change) is less than three degrees Fahrenheit
(.degree. F.) of discharge line temperature over a time frame of
two minutes. Thus the target threshold value may be three degrees
Fahrenheit (.degree. F.). However, it is understood that the target
threshold value threshold may change with each different system or
application type. Some systems may stabilize faster than others.
For example, if the system uses an electronic expansion valve
rather than a traditional thermal expansion valve (TXV), the
electronic expansion valve system will stabilize faster than the
traditional system having the TXV. Thus, while an example of three
degrees Fahrenheit (.degree. F.) is provided, different target
threshold values may be utilized to determine stability or steady
state operation for different systems and application types.
[0073] As stated above, the system controller 46 may determine
stabilization of the compressors 26, 30, 34 in the multi-linked
compressors 14 through monitoring a common discharge line
temperature. The system controller 46 may communicate with
discharge line temperature sensor 58 to receive the common
discharge line temperature. Alternatively, stabilization may be
determined from the signal output of the current sensor 50 or the
signal output of the suction line temperature sensor 54. The system
controller 46 may determine that the multi-linked compressors 14
have stabilized when the discharge line temperature, the signal
from the current sensor 50, or the suction line temperature sensor
54 becomes steady and/or a derivative of the temperatures or the
current signal goes to zero.
[0074] The processing circuitry 86 communicates with the memory 78
and may receive the ten coefficient performance models and the
identity and position of each compressor 26, 30, 34 in the
multi-linked compressors 14 from the memory 78. From the inputs,
the processing circuitry 86 may determine a current estimated
system capacity (ESC) for the activated compressors in the
multi-linked compressors 14 at step 116 based on the current
saturated evaporator temperature, saturated condensing temperature,
and the applicable ten coefficient performance model for the
current group of activated compressors in the multi-linked
compressors 14. The estimated system capacity may be the same as or
close to the target capacity or the capacity demand from step 104.
For example only, the estimated system capacity or target capacity
may be determined from the ten coefficient performance models and
the compressor efficiency formula previously described.
[0075] The processing circuitry 86 may receive the common discharge
line temperature, saturated evaporator temperature, and saturated
condensing temperature from various sensors or may calculate the
common discharge line temperature, saturated evaporator
temperature, and saturated condensing temperature from other
received sensor data, as previously described. The processing
circuitry 86 may then determine estimated compressor capacity and
associated estimated power consumption values for all applicable
operating modes for the multi-linked compressors 14 from the
various inputs at step 120. For example only, compressor capacity
may be calculated using the ten coefficient performance models for
estimating compressor capacity and power consumption. As described
above with reference to FIG. 3, each discrete operating mode
includes a combination of activated compressors, with any two-stage
compressors operating at a particular operating level. The
processing circuitry 86 uses the ten coefficient performance models
for capacity and power to calculate the estimated capacity and the
estimated power consumption for each discrete operating mode
associated with the multi-linked compressors 14. For example, as
shown in FIG. 3, an uneven trio of compressors has eleven
associated operating modes. In such case, the processing circuitry
will calculate an estimated capacity and an estimated power
consumption for each of the eleven operating modes using the ten
coefficient performance models for the uneven trio of
compressors.
[0076] At step 124, the processing circuitry 86 receives a capacity
error tolerance (ET) from the memory 78. The ET may be saved in the
memory and initially set by an installer or manufacturer. The ET
may also be modified by a user of the system. The processing
circuitry 86 then compares the estimated capacity values for each
discrete operating mode to the target capacity and eliminates from
consideration all modes with an estimated capacity value that is
outside of the target system capacity plus or minus the error
tolerance (ET) at step 128. In other words, any operating modes
with an estimated capacity value that is not within the error
tolerance (ET) of the target system capacity are eliminated from
consideration.
[0077] At step 132, the processing circuitry 86 analyzes the power
values for the remaining operating modes in consideration and
selects the operating mode with the lowest estimated power
consumption value from the operating modes that were not eliminated
in step 128. The lowest power mode of the modes meeting the
estimated system capacity is the optimum mode because the lowest
power mode meets target capacity, plus or minus the error tolerance
(ET) while using the least amount of power. In other words, the
optimum operating mode corresponds to the configuration of the
multi-linked compressors 14 that can meet the target capacity while
consuming the least amount of power.
[0078] At step 136, the processing circuitry 86 activates
contactors 38 and solenoids 36 of the multi-linked compressors 14
as needed to achieve the optimum mode or an optimized state. As
discussed above, the optimized state will meet the capacity needs
at the lowest power mode. In some cases, the current operating mode
of the multi-linked compressors 14 may already correspond to the
optimum operating mode. In such case, the processing circuitry 86
will not need to activate or deactivate any compressors or change
the capacity level of any two-stage compressors to achieve the
optimum operating mode. In other cases, the current operating mode
may be different from the optimum operating mode. In such case, the
processing circuitry 86 activates and deactivates compressors and
commands any two-stage compressors to operate at the appropriate
capacity level, as necessary, to accomplish the optimum operating
mode.
[0079] At step 140, the processing circuitry 86 waits for and
determines stabilization of the multi-linked compressors. For
example, the processing circuitry waits until a derivative of the
discharge line temperature out of the multi-linked compressor 14
approaches stability. For example only, the derivative of the
discharge line temperature reaches stability when the derivative
value to approaches a low value or threshold value for a set period
of time (for example only, where the derivative value is less than
three degrees Fahrenheit (.degree. F.) over a time frame of two
minutes). When the derivative of the discharge line temperature
approaches stability, the multi-linked compressors 14 are operating
in the optimized state. The optimized state, or optimization state,
optimizes compressor modulation to both meet the capacity demand
from the refrigerant system 12 and optimizes the performance of the
multi-linked compressors 14 by minimizing power consumption.
[0080] At step 144, the system controller 46 may command the
processing circuitry 86 to shut down compressors in the
multi-linked compressors 14 once the demand for capacity has been
removed. For example, once the target temperature within a cooled
or refrigerated space has been reached, the system may remove the
demand for cooling. The processing circuitry 86 then follows a
pre-programmed powered shut down routine. The processing circuitry
86 will shut down the compressors of the multi-linked compressors
14 one at a time. For example only, the compressors may be shut
down in the order of highest capacity compressor to lowest capacity
compressor. In another example, the compressors may be shut down in
order of position, shutting off C first, then B, then A.
[0081] Based on cooling requirements, instead of proceeding to step
144, the system controller 46 may command a new capacity. In such
case, the processing circuitry will then return to step 104 and
start the optimization algorithm over again.
[0082] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific components, devices, and methods, to provide a
thorough understanding of embodiments of the present disclosure. It
will be apparent to those skilled in the art that specific details
need not be employed, that example embodiments may be embodied in
many different forms and that neither should be construed to limit
the scope of the disclosure. In some example embodiments,
well-known processes, well-known device structures, and well-known
technologies are not described in detail.
[0083] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an," and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
[0084] Although the terms first, second, third, etc. may be used
herein to describe various elements, components, regions, layers
and/or sections, these elements, components, regions, layers and/or
sections should not be limited by these terms. These terms may be
only used to distinguish one element, component, region, layer or
section from another region, layer or section. Terms such as
"first," "second," and other numerical terms when used herein do
not imply a sequence or order unless clearly indicated by the
context. Thus, a first element, component, region, layer or section
discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of
the example embodiments.
[0085] Spatially relative terms, such as "inner," "outer,"
"beneath," "below," "lower," "above," "upper," and the like, may be
used herein for ease of description to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Spatially relative terms may be
intended to encompass different orientations of the device in use
or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an
orientation of above and below. The device may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein interpreted
accordingly.
[0086] In this application, including the definitions below, the
terms controller or module may be replaced with the term circuit.
The terms controller or module may refer to, be part of, or include
an Application Specific Integrated Circuit (ASIC); a digital,
analog, or mixed analog/digital discrete circuit; a digital,
analog, or mixed analog/digital integrated circuit; a combinational
logic circuit; a field programmable gate array (FPGA); a processor
(shared, dedicated, or group) that executes code; memory (shared,
dedicated, or group) that stores code executed by a processor;
other suitable hardware components that provide the described
functionality; or a combination of some or all of the above, such
as in a system-on-chip.
[0087] The term code, as used above, may include software,
firmware, and/or microcode, and may refer to programs, routines,
functions, classes, and/or objects. The term shared processor
encompasses a single processor that executes some or all code from
multiple modules. The term group processor encompasses a processor
that, in combination with additional processors, executes some or
all code from one or more modules. The term shared memory
encompasses a single memory that stores some or all code from
multiple modules. The term group memory encompasses a memory that,
in combination with additional memories, stores some or all code
from one or more modules. The term memory may be a subset of the
term computer-readable medium. The term computer-readable medium
does not encompass transitory electrical and electromagnetic
signals propagating through a medium, and may therefore be
considered tangible and non-transitory. Non-limiting examples of a
non-transitory tangible computer readable medium include
nonvolatile memory, volatile memory, magnetic storage, and optical
storage.
[0088] The apparatuses and methods described in this application
may be partially or fully implemented by one or more computer
programs executed by one or more processors. The computer programs
include processor-executable instructions that are stored on at
least one non-transitory tangible computer readable medium. The
computer programs may also include and/or rely on stored data.
[0089] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
* * * * *