U.S. patent application number 13/560726 was filed with the patent office on 2013-02-21 for solar synchronized loads for photovoltaic systems.
This patent application is currently assigned to Robert Boach GmbH. The applicant listed for this patent is Eric Daniels, John Saussele. Invention is credited to Eric Daniels, John Saussele.
Application Number | 20130043724 13/560726 |
Document ID | / |
Family ID | 47631958 |
Filed Date | 2013-02-21 |
United States Patent
Application |
20130043724 |
Kind Code |
A1 |
Daniels; Eric ; et
al. |
February 21, 2013 |
Solar Synchronized Loads for Photovoltaic Systems
Abstract
An electrical power supply arrangement includes a solar power
device that converts sunlight into DC electrical power. A DC load
runs on the DC current electrical power. The DC load may be
controlled or adjusted to consume a maximum amount of the
electrical output of the solar power device. A DC-to-AC converter
converts the DC electrical power into AC electrical power. A
controller enables the DC-to-AC converter to receive a portion of
the DC current electrical power from the solar power device only if
all of the DC current electrical power cannot be consumed by the DC
load.
Inventors: |
Daniels; Eric; (Union Hall,
VA) ; Saussele; John; (Davidson, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Daniels; Eric
Saussele; John |
Union Hall
Davidson |
VA
NC |
US
US |
|
|
Assignee: |
Robert Boach GmbH
Stuttgart
IL
Robert Bosch LLC
Broadview
|
Family ID: |
47631958 |
Appl. No.: |
13/560726 |
Filed: |
July 27, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13489412 |
Jun 5, 2012 |
|
|
|
13560726 |
|
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|
61525483 |
Aug 19, 2011 |
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Current U.S.
Class: |
307/23 ; 307/31;
363/84; 363/95 |
Current CPC
Class: |
H02J 7/35 20130101; Y02B
70/3225 20130101; H02J 2310/14 20200101; H02M 7/44 20130101; H02J
3/383 20130101; Y04S 20/242 20130101; H02J 2300/24 20200101; Y02E
10/56 20130101; Y02B 70/30 20130101; Y02B 10/10 20130101; H02J 3/14
20130101; H02J 3/381 20130101; Y04S 20/222 20130101 |
Class at
Publication: |
307/23 ; 307/31;
363/95; 363/84 |
International
Class: |
H02J 1/00 20060101
H02J001/00; H02M 7/44 20060101 H02M007/44; H02M 7/04 20060101
H02M007/04; H02J 9/00 20060101 H02J009/00 |
Claims
1. An electrical power supply arrangement comprising: a solar power
device configured to convert sunlight into DC electrical power; at
least one adjustable DC load configured to run on the DC current
electrical power; an electrical output sensing device configured to
sense a level of electrical output of the solar power device; and a
controller coupled to each of the at least one adjustable DC load
and the electrical output sensing device, the controller being
configured to: receive a signal from the electrical output sensing
device; adjust the at least one adjustable DC load such that the at
least one adjustable DC load consumes a maximum amount of the
electrical output of the solar power device, the adjusting of the
at least one adjustable DC load being dependent upon the received
signal; and if the at least one adjustable DC load cannot consume
all of the electrical output of the solar power device, then cause
a remaining portion of the electrical output of the solar power
device to be converted into AC electrical power.
2. The arrangement of claim 1 wherein the solar power device
comprises a solar photovoltaic device.
3. The arrangement of claim 1 wherein the electrical output sensing
device comprises a power meter.
4. The arrangement of claim 1 wherein the adjustable DC load
comprises an HVAC system.
5. The arrangement of claim 4 wherein the HVAC system comprises a
circulation fan, the controller being configured to use power from
the solar power device to operate the circulation fan while heating
and cooling is not needed.
6. The arrangement of claim 4 wherein the HVAC system comprises a
compressor, the controller being configured to use power from the
solar power device to operate the compressor in a dehumidification
mode while heating and cooling is not needed.
7. The arrangement of claim 4 wherein the controller is configured
to use power from the solar power device to perform overheating or
overcooling with the HVAC system beyond a set temperature of the
HVAC system, the set temperature having been set by a human
user.
8. The arrangement of claim 1 further comprising a battery
configured to supplement the DC electrical power provided by the
solar power device.
9. An electrical power supply method, comprising the steps of:
converting sunlight into DC electrical power by use of a solar
power device; providing the DC current electrical power to a
plurality of adjustable DC loads; sensing a level of electrical
output of the solar power device; and adjusting each of the DC
loads such that the DC loads conjointly consume a maximum amount of
the electrical output of the solar power device, the adjusting of
the DC loads being dependent upon the level of electrical output of
the solar power device.
10. The method of claim 9 comprising the further step, if the DC
loads cannot consume all of the electrical output of the solar
power device, of converting a remaining portion of the electrical
output of the solar power device into AC electrical power.
11. The method of claim 9 comprising the further step of
determining a respective portion of the electrical output of the
solar power device to be consumed by each of the loads.
12. The method of claim 11 wherein the determining step is
performed by use of an algorithm or a lookup table.
13. The method of claim 11 wherein the determining step includes
controlling a rate of change of an aggregate consumption of the
electrical output of the solar power device by the loads such that
the rate of change does not exceed a threshold rate of change.
14. The method of claim 11 wherein each of the loads includes a
processor, the determining step including the processors of the
loads communicating with each other.
15. An electrical power supply arrangement comprising: a solar
power device configured to convert sunlight into DC electrical
power; a DC load configured to run on the DC current electrical
power; a DC-to-AC converter configured to convert the DC electrical
power into AC electrical power; and a controller configured to
enable the DC-to-AC converter to receive a portion of the DC
current electrical power from the solar power device only if all of
the DC current electrical power cannot be consumed by the DC
load.
16. (canceled)
17. The arrangement of claim 15 further comprising an AC-to-DC
power supply configured to supply DC electrical power to the DC
load if sunlight is not available to the solar power device.
18. The arrangement of claim 15 further comprising a DC power bus
interconnecting the solar power device and the DC load.
19. The arrangement of claim 15 wherein the DC load comprises an
appliance.
20. The arrangement of claim 19 wherein the appliance comprises
HVAC equipment.
21. An electrical power supply arrangement comprising: A first AC
load configured to run on AC electrical power; a solar power device
configured to convert sunlight into DC electrical power; an
adjustable electric motor powered by the DC electrical power; and a
motor control circuit coupling the solar power device to the
adjustable electric motor and to the first AC load, the motor
control circuit being configured to control operation of the
adjustable electric motor, the motor control circuit including a
first inverter configured to invert the DC electrical power into AC
electrical power for the first AC load only if the adjustable
electrical motor is unable to entirely consume the DC electrical
power.
22. The arrangement of claim 21, wherein the first AC load receives
power only through the motor control circuit.
23. The arrangement of claim 21, wherein the motor control circuit
further couples the solar power device to a DC load separate from
the electric motor.
24. The arrangement of claim 21, wherein the motor control circuit
further includes an inverter coupling the solar power device to a
DC load, the inverter being configured to convert a first voltage
of the DC electrical power provided by the solar power device to a
second voltage suitable for powering the DC load.
25. The arrangement of claim 21, wherein the motor control circuit
further includes a second inverter configured to invert the DC
electrical power into AC electrical power for a second AC load only
if the adjustable electric motor and the first AC load together are
unable to entirely consume the DC electrical power.
26. The arrangement of claim 21, wherein the motor control circuit
further couples the solar power device to a battery configured to
supplement the DC electrical power provided by the solar power
device.
27. The arrangement of claim 21, wherein the adjustable electric
motor drives at least one of an HVAC compressor and an HVAC
circulation fan.
28. The arrangement of claim 21, wherein the adjustable electric
motor is a DC motor.
29. The arrangement of claim 21 wherein the motor control circuit
includes a Variable Frequency Drive including a DC input, the
Variable Frequency Drive being configured to vary a speed of the
electric motor such that the electric motor consumes a maximum
amount of the electrical output of the solar power device.
30. The arrangement of claim 21 wherein the motor control circuit
is directly connected to the solar power device.
31. The arrangement of claim 21 further comprising an electrical
output sensing device coupled to the motor control circuit and
configured to sense a level of electrical output of the solar power
device, the motor control circuit being configured to: receive a
signal from the electrical output sensing device; adjust operation
of the adjustable electrical motor such that the adjustable
electrical motor consumes a maximum amount of the electrical output
of the solar power device, the adjusting of the adjustable
electrical motor being dependent upon the received signal; and if
the adjustable electrical motor cannot consume all of the
electrical output of the solar power device, then cause a remaining
portion of the electrical output of the solar power device to be
converted into AC electrical power.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of, and claims the
benefit of, nonprovisional application Ser. No. 13/489,412, filed
Jun. 5, 2012, entitled "Solar Synchronized Loads for Photovoltaic
Systems", by applicants Eric Daniels and John Saussele, and
provisional application 61/525,483, filed Aug. 19, 2011, entitled
"DC Power Bus for Solar Photovoltaics", by applicants Eric Daniels
and John Saussele, each of which is hereby incorporated by
reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to solar power, and, more
particularly, to running DC loads by use of solar power.
[0004] 2. Description of the Related Art
[0005] Current solar photovoltaic (PV) systems for residential and
commercial buildings typically produce direct current (DC) which is
inverted to alternating current (AC) using inverters in and
connected to an AC circuit breaker box within or on the building.
Such systems suffer from power intermittency caused when the grid
must make up any short term reduction in PV output. Current HVAC
systems such as heat pumps often utilize AC-to-DC-to-AC, AC motor
controls or AC-to-DC power supplies especially when the fans or
compressors have variable-speed motors. There are a variety of
variable-speed motors which could utilize DC input. Examples are
brushless DC motors (BLDC motors) also known as electronically
commutated motors (ECM), as well as variable-frequency drives (VFD)
for AC motors, which may also be configured to use DC as the input
to the VFD. For example, a Bosch brand geothermal heat pump uses
AC-to-DC power supply to power a variable speed ECM fan motor. For
the purposes of this invention description, the phrase "DC motor"
refers to any motor system where DC is the PV input to the motor or
motor controls, even in the case of a DC input VFD controlling a
variable speed AC motor or similar.
[0006] It is known to convert all of the DC from PV to AC for use
by AC building loads or for export to the utility grid. What is not
known in the conventional art is to adjust DC loads such that the
DC loads consume a maximum amount of the DC electrical output of
the solar panels, and to convert DC power from solar panels to AC
only if all of the DC power is not being consumed by a DC load.
Moreover, it is not known to purposefully manage loads, in a
variable manner, on the demand side of the meter in concert with
the variability of PV power for the purpose of reduction in or
avoidance of power intermittency on the grid. Further, it is not
known in the conventional art that the DC load is in the form of an
HVAC system, such as a heat pump with DC input to the DC phase of
AC-DC-AC motor controls.
SUMMARY OF THE INVENTION
[0007] The invention is directed to an HVAC power supply
arrangement in which the DC output from a solar array is either
directly or through DC/DC converters connected to the DC circuits
of the HVAC equipment. The variable-speed DC motor may be
controlled or adjusted to consume a maximum amount of the
electrical output of the solar panels, increasing consumption when
output is higher, lowering consumption when output is lower. An
inverter that is either within (motor control circuits for
instance) or separate from the HVAC equipment may operate in a
bidirectional mode to invert the DC output from the solar array to
AC for the home circuit if the output energy is not being entirely
consumed by the variable-speed DC motor. This technique also
enables the integration of a DC power bus within the home or
commercial building for direct coupling to DC appliances and other
DC devices.
[0008] In one embodiment, the invention comprises an electrical
power supply arrangement including a solar power device that
converts sunlight into DC electrical power. An adjustable DC load
runs on the DC current electrical power. An electrical output
sensing device senses a level of electrical output of the solar
power device. A controller is coupled to each of the adjustable DC
loads and the electrical output sensing device. The controller
receives a signal from the electrical output sensing device, and
adjusts the DC load such that the DC loads consumes substantially
all of the electrical output of the solar power device. The
adjusting of the DC loads is performed dependent upon the received
signal, and depending on which other loads need to receive power.
For example, it may be determined how much of the available
solar-generated electricity should be sent to the HVAC systems and
how much should be sent to other loads, such as a charging station
for an Electric Vehicle (EV).
[0009] In another embodiment, the invention comprises an electrical
power supply arrangement including a solar power device that
converts sunlight into DC electrical power. A DC load runs on the
DC current electrical power. A DC-to-AC converter converts the DC
electrical power into AC electrical power. A controller enables the
DC-to-AC converter to receive a portion of the DC current
electrical power from the solar power device only if all of the DC
current electrical power cannot be consumed by the DC load.
[0010] In yet another embodiment, the invention comprises an
electrical power supply method including converting sunlight into
DC electrical power by use of a solar power device. The DC current
electrical power is provided to a plurality of adjustable DC loads.
A level of electrical output of the solar power device is sensed.
Each of the DC loads is adjusted such that the DC loads conjointly
consume a maximum amount of the electrical output of the solar
power device. The adjusting of the DC loads is dependent upon the
level of electrical output of the solar power device.
[0011] In yet another embodiment, the invention comprises an
electrical power supply method including converting sunlight into
DC electrical power by use of a solar power device. The DC current
electrical power is provided to an inverter to provide power to an
AC load. A level of electrical output of the solar power device is
sensed. The AC load or series of AC loads are operated in a
variable fashion that optimizes the consumption of the variable PV
DC electrical power in a manner which intends to eliminate or
reduce AC power demands from the utility grid. The adjusting of the
AC loads is dependent upon the level of electrical output of the
solar power device.
[0012] The invention may eliminate the need to have an inverter
between the photovoltaic (PV) system and the circuit breaker box.
Instead, the DC output from the solar array may be either directly,
or through DC/DC converters, connected to the DC circuits of the
HVAC equipment. The inverter within the HVAC equipment then may act
in a bidirectional mode to invert the DC from the solar array to AC
for the home circuit or utility grid, if the output energy is not
being entirely consumed by the variable-speed DC motor or other DC
loads in the building. This technique also enables the integration
of a DC power bus within the home or commercial building for direct
coupling to DC appliances and other DC devices. The elimination of
the traditional inverter conventionally used for solar systems may
greatly reduce system cost, reduce electrical losses due to the
inversion, and may result in increased system efficiency at lower
cost. The invention may achieve the lower cost, higher efficiency,
and higher reliability through simplification of the system.
[0013] In another embodiment, electrical DC loads (e.g., HVAC
systems, appliances, EV chargers, water pumps, etc.) are adjusted
in a variable manner such that the power consumption of the loads
corresponds as closely as possible to the power available from a PV
system. This adjustment of the DC loads is intended to result in
less variation in the demand on other power sources in the system
(e.g., the utility grid, battery, etc.) by the DC loads. In such
applications, the PV output is designed to provide adequate power
to the load without call for additional power from the utility or
storage device. Utility or storage power is intended to only
provide power during evenings or emergencies. This adjustment of
the DC loads may also reduce system losses, minimize utility
transformer size, lower system costs, and increase the ability of
the utility grid to support higher penetration levels of renewable
energy. Such application allows the utilities to avoid the added
costs of spinning reserves for the purpose of managing the power
intermittency caused by traditional PV system designs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above mentioned and other features and objects of this
invention, and the manner of attaining them, will become more
apparent and the invention itself will be better understood by
reference to the following description of embodiments of the
invention taken in conjunction with the accompanying drawings,
wherein:
[0015] FIG. 1 is a block diagram of one embodiment of an electrical
power supply arrangement of the present invention.
[0016] FIG. 2 is a block diagram of another embodiment of an
electrical power supply arrangement of the present invention.
[0017] FIG. 3 is a flow chart of one embodiment of an electrical
power supply method of the present invention.
[0018] FIG. 4 is a block diagram of yet another embodiment of an
electrical power supply arrangement of the present invention.
[0019] FIG. 5 is a diagram illustrating communication between DC
loads according to another embodiment of an electrical power supply
method of the present invention.
[0020] FIG. 6 is a block diagram of still another embodiment of an
electrical power supply arrangement of the present invention.
[0021] Corresponding reference characters indicate corresponding
parts throughout the several views. Although the exemplification
set out herein illustrates embodiments of the invention, in several
forms, the embodiments disclosed below are not intended to be
exhaustive or to be construed as limiting the scope of the
invention to the precise forms disclosed.
DESCRIPTION OF THE PRESENT INVENTION
[0022] Referring now to the drawings, and particularly to FIG. 1,
there is illustrated one embodiment of an electrical power supply
arrangement 10 of the present invention including a solar PV array
12, and a DC power bus 14 electrically connecting array 12 to a
bidirectional inverter 16 of an HVAC system 18 (or DC input to the
DC phase in an AC-DC-AC motor controller circuit). Inverter 16 may
convert DC voltage from array 12 to a DC voltage level that is
appropriate for use by HVAC system 18. Array 12 may include a
DC-to-DC converter which may convert the DC voltage output by the
solar array to a voltage level suitable for transmission on bus 14.
Inverter 16 may also convert DC voltage from array 12 to an AC
voltage that may be used through the remainder of a house 20 with
which arrangement 10 is associated. Excess AC power that cannot be
used within house 20 may be provided to a grid 22 for use outside
of house 20. In one embodiment, DC voltage from array 12 may be
converted to AC voltage by inverter 16 only if HVAC system 18 (or
other variable AC or DC loads) cannot consume all of the DC power
from array 12.
[0023] By transferring the DC voltage from array 12 directly to
HVAC system 18, arrangement 10 may eliminate the need for a
separate inverter to convert the DC voltage from array 12 to AC
voltage for transmission and use by both AC loads and DC loads
(after conversion of the AC voltage back to DC voltage). The
omission of the separate inverter may reduce electrical losses,
reduce cost, and provide improved reliability of the system.
Moreover, the invention may provide a high voltage DC power bus 14
which may be used by other appliances within the building or EV
charging systems.
[0024] In another embodiment, the bidirectional inverter may simply
be a DC drive or DC motor, and an optional, often smaller, inverter
may be added to the DC bus. The need for an inverter and the size
of the inverter may be determined by the amount of PV energy, if
any, that could not be consumed by the DC loads under certain
building circumstances.
[0025] In an alternative embodiment (not shown), the DC/DC
conversion at PV array 12 is omitted. That is, the DC voltage may
be transmitted on bus 14 in the same voltage as produced by the
solar cells of array 12.
[0026] In another embodiment (FIG. 2), an electrical power supply
arrangement 100 of the present invention includes a DC load 118
which can be adjusted by a controller 124 to maximize the use of a
varying PV output of a solar array 112. That is, a power meter 126
or a similar device may sense the output power of solar array 112
and communicate the sensed reading to controller 124, as indicated
at 128. In turn, controller 124 can adjust DC load 118, as
indicated at 130, such that load 118 consumes substantially all of
the power that solar array 112 can produce. Thus, no inverter, or a
reduced size inverter, may be needed to feed excess PV output into
the utility grid (not shown). A practical example would be to run
air conditioning motors at lower speed for a longer time under the
reduced solar power output of lower light (e.g., cloudy)
conditions. This could achieve the same building cooling, while
reducing the variation (intermittency) of power on the grid, which
is highly desirable to the utility companies. Also, by the load(s)
using the entire amount of electrical power produced by the solar
array, the invention avoids the energy losses associated with
converting the DC power from the solar array to AC power,
transferring the AC power to the grid, receiving AC power from the
grid, and converting the AC power from the grid to DC power.
[0027] The same principle may apply to systems utilizing battery
storage in place of, or in addition to, solar arrays. In this case,
the battery controller and/or charge controller could be reduced or
eliminated by adjusting the load to consume all of the power output
of the battery. In one embodiment, the battery ensures that a
minimum required level of electrical power may be provided to the
load when the solar array cannot provide the minimum required level
of electrical power. For example, the battery may power the
electronic controller as well as any electronics operating in
association with the load. For example, a battery may keep lights
operating on the load at night so that a user can interact with the
load, even though the solar array cannot provide power to keep the
load fully operating until daylight in the morning. The battery may
be recharged by the solar array in the event that the solar array
produces more power than is required by the load. In addition,
synchronizing the loads to the available solar energy could reduce
the amount and frequency of charging and discharging batteries in
the system which may extend the battery life. Solar Synchronized
Loads can also improve battery life by reducing the intermittency
in battery charging/discharging in the same way as intermittency in
utility grid demand is reduced.
[0028] An electrical power supply method 300 (FIG. 3) of the
invention is described below with reference to FIGS. 4 and 5. In a
first step 302, sunlight is converted into DC electrical power by
use of a solar power device. For example, electrical power supply
arrangement 400 (FIG. 4) includes a solar array 412 which converts
sunlight into DC electrical power.
[0029] In a next step 304, the DC current electrical power is
provided to a plurality of adjustable DC loads. As shown in the
specific embodiment of FIG. 4, a plurality of DC loads 418a through
418n each receives and runs on the DC current electrical power
generated by solar array 412. Alternatively, DC loads 418 may be AC
loads.
[0030] Next, in step 306, a level of electrical output of the solar
power device is sensed. For example, a power meter 426 or a similar
device may sense the output power of solar array 412 and
communicate the sensed reading to controller 424, as indicated at
428.
[0031] In step 308, each of the DC loads is adjusted such that the
DC loads conjointly consume a maximum amount of the electrical
output of the solar power device. The adjusting of the DC loads is
dependent upon the level of electrical output of the solar power
device. In the example embodiment of FIG. 4, controller 424 can
adjust each of DC loads 418a-n, as indicated at 430a-n, such that
loads 418a-n in combination consume substantially all of the power
that solar array 412 can produce. Thus, no inverter, or a reduced
size inverter, may be needed to feed excess PV output into the
utility grid (not shown). For example, loads 418a-n may represent n
number of air conditioning motors each of which is primarily
responsible for cooling a respective section of a building. In an
alternative embodiment, loads 418a-n may represent n number of
refrigeration and/or ice-making motors. Although the various
sections of the building may be at or below the desired set
temperature (e.g., 72 degrees F.), AC motors 418a-n may continue to
run during and around the noon hour when sunlight is most direct
and thus the output of solar array 412 is greatest. Thereby, the
various sections of the building may be "overcooled" to a
temperature of approximately between 68 and 71 degrees F., for
example. By virtue of such overcooling, AC motors 418a-n may
require less electrical power output from solar array 412 in the
late afternoon when sunlight is less direct and the electrical
power output capability of solar array 412 is lower. Thus, the
building may be efficiently cooled with only small variations in
temperature which may not be noticeable to the inhabitants of the
building. Also, the variation in the amount of power require from
the grid may be reduced, which is highly desirable to the utility
companies. Further, by the loads using the full amount of
electrical power produced by the solar array, the invention avoids
the energy losses associated with converting the DC power from the
solar array to AC power, transferring the AC power to the grid,
receiving AC power from the grid, and converting the AC power from
the grid to DC power.
[0032] In a next step 310, a respective portion of the electrical
output of the solar power device to be consumed by each of the
loads is determined, possibly by use of an algorithm or a lookup
table. For example, if DC loads 418a-n represent n number of air
conditioning motors cooling respective sections of a building, then
each of the sections of the building may be at different actual
temperatures, and possibly may have different set temperatures.
Thus, controller 424 may adjust air conditioning (or cooling
equipment) motors 418a-n such that each motor consumes an amount or
portion of electrical power that varies with the difference between
the actual temperature and the set temperature of the motor's
respective building section. The algorithm or lookup table may take
into account expected thermal conditions in each of the building
sections in the immediate future (e.g., in the next three hours).
For example, a section on the west side of the building that is
more exposed to sunlight may be expected to heat up more in the
next few afternoon hours, and thus the respective air conditioning
motor may be adjusted to consume a greater portion of the
electrical power output of solar array 412. Generally, the HVAC
equipment may no longer operate in a digital fashion as in all on
or all off. Instead, the compressor and blower unit may operate at
levels consistent with the output of the solar array. When the sun
shines strongest, heat loads tend to be highest. The same principle
applies to ice-making and refrigeration.
[0033] The step 310 of determining a respective portion of the
electrical output of the solar power device to be consumed by each
of the loads may include controlling a rate of change of an
aggregate consumption of the electrical output of the solar power
device by the loads such that the rate of change does not exceed a
threshold rate of change. Thus, the amount of power drawn from
solar array 412 may change with a gradual ramp up in order to avoid
spikes of power being sent to and/or from the grid. Such spikes may
result in inefficiencies and wasted energy. For example, controller
424 may adjust loads 418a-n such that a rate of change of power
consumption by loads 418a-n does not exceed a threshold or maximum
level of Watts per second of time. If the load requires more energy
than can be delivered from the array, a signal may be sent to the
utility advising that the load is planning a gradual ramp and an
increased power call from the utility. The timing of the ramp may
be adjustable based upon a feedback loop (power availability) from
the utility.
[0034] Each of the loads may include a respective processor, and
the step of determining a respective portion of the electrical
output of the solar power device to be consumed by each of the
loads may include communication between the processors. For
example, as shown in FIG. 5, loads 518a-e each includes a
respective one of processors 532a-e. Each of processors 532a-e may
communicate directly with each of the other ones of processors
532a-e, as indicated by the dashed double-sided arrows in FIG. 5.
The communication between processors 532a-e may occur wirelessly,
or may be carried by same the electrical conductors that carry
power to loads 518a-e. In one embodiment, processors 532a-e
communicate with each other in order to conjunctively determine how
much power will be drawn by each of loads 518a-e. For example,
processors 532a-e may conjunctively determine how much power will
be drawn by each of loads 518a-e such that all of the power
produced by the solar array is consumed. Alternatively, or in
addition, processors 532a-e may conjunctively determine how much
power will be drawn by each of loads 518a-e such that a rate of
change of power consumption by loads 518a-e does not exceed a
threshold or maximum level of Watts per second of time.
[0035] In a final step 312 (FIG. 3), if the DC loads cannot consume
all of the electrical output of the solar power device, then a
remaining portion of the electrical output of the solar power
device is converted into AC electrical power. There may also be
situations in which the load 418a-n are capable, strictly speaking,
of consuming all of the electrical output of the solar power device
412, but processor 424 does not allow one or more the loads 418a-n
to consume all the power they are capable of consuming in order to
avoid damaging or overheating loads 418a-n. In the above-described
embodiment including loads in the form of air conditioning motors,
processor 424 may not allow one or more the motor to consume all
the power they are capable of consuming in order to avoid burning
out the motors. Regardless of whether the loads are physically
incapable of consuming all of the electrical output of the solar
power device or the processor prevents the loads from consuming all
of the electrical output of the solar power device strictly to
avoid damaging the loads, the remaining portion of the electrical
output of solar array 412 may be converted in AC electrical power.
This AC electrical power may then be consumed by AC appliances
within the building, consumed by full home, commercial building
loads, or sent to the grid for use by other consumers.
[0036] Other features of electrical power supply arrangement 400
may be substantially similar to those of electrical power supply
arrangement 100 as described above, and thus are not further
described herein in order to avoid needless repetition.
[0037] In FIG. 6 there is illustrated still another embodiment of
an electrical power supply arrangement 610 of the present invention
including a solar PV array 612, and a DC power bus 614 electrically
connecting array 612 to a bidirectional inverter 616 associated
with a DC load 618. Inverter 616 may convert DC voltage from array
612 to a DC voltage level that is appropriate for use by DC load
618. A uni-directional (e.g., one-way) power connector 634 may
couple DC load 618 to inverter 616. Connector 634 may allow current
to flow in only one direction (e.g., from inverter 616 to load
618), and may prevent current from flowing from load 618 to
inverter 616 if load 618 happens to function as a generator for a
brief period. In one embodiment, connector 634 may be in the form
of one or more diodes (not shown). Thus, uni-directional connector
634 may prevent power from load 618 from damaging inverter 616.
[0038] Array 612 may include a DC-to-DC converter which may convert
the DC voltage output by the solar array to a voltage level
suitable for transmission on bus 614. Inverter 616 may also convert
DC voltage from array 612 to an AC voltage that may be used through
the remainder of a house 620 with which arrangement 610 is
associated. Excess AC power that cannot be used within house 620
may be provided to a grid 622 for use outside of house 620. In one
embodiment, DC voltage from array 612 may be converted to AC
voltage by inverter 616 only if HVAC system 618 (or other variable
AC or DC loads) cannot consume all of the DC power from array 612.
A uni-directional (e.g., one-way) power connector 636 may couple
array 612 to inverter 616. Connector 636 may allow current to flow
in only one direction (e.g., from array 612 to inverter 616), and
may prevent current from flowing from inverter 616 to array 612. In
one embodiment, connector 636 may be in the form of one or more
diodes (not shown). Thus, uni-directional connector 636 may prevent
power from inverter 616 from damaging electronics associated with
array 612.
[0039] As the invention may be applied to an HVAC system as the
load, if heating or cooling is not needed while the PV electrical
output is available, the circulation fan could still run to provide
air filtering functionality. Similarly, the compressor could run in
a dehumidification mode. Buildings can also be "overcooled" or
"overheated" by a slight amount, reducing future energy demand.
Thus, by use of these techniques, all of the electrical power
produced by the PV may be consumed by the HVAC system.
[0040] As the invention may be applied to a freezer or refrigerator
as the load, the motor speed of the freezer's compressor could be
varied to match or completely consume the PV electrical output. Any
excess electrical output could be used to "overcool", or further
lower, the freezer temperature beyond the temperature that would
ordinarily be called for. This allows the thermal energy stored in
the freezer to be recovered at night (when there may be no PV
electrical output), thereby enabling the freezer to draw a lower
level of electrical power from other sources.
[0041] As the invention may be applied to a heat pump or
conventional electric hot water heater as the load, the load can be
adjusted to match or completely consume the PV electrical output.
Any excess PV electrical output may be used to "overheat" the water
above the temperature that would ordinarily be called for. Thus,
the need to draw power from other non-PV sources during the day or
at night is reduced.
[0042] As the invention may be applied to a water pump as the load,
the pump could be run at variable speed to match or completely
consume the PV output. Any extra water that is pumped at a higher
motor speed may be stored or deployed during the daytime, thereby
reducing the nighttime needs for pumping water.
[0043] As the invention may be applied to electric vehicle charging
as the load, the battery charge rate can vary with PV electrical
output. A DC power bus between the PV system and the DC motor loads
may provide an efficient way to vary the load. PV modules output DC
voltage, so utilizing the DC voltage directly via the DC power bus
without conversion to AC voltage may reduce conversion losses.
[0044] In one embodiment, a DC input Variable Frequency Drive (VFD)
for an AC motor or DC brushless motor provides an efficient way to
vary the speed of a motor and thereby vary the load to match the PV
electrical output. The DC input Variable Frequency Drive may be
employed to vary the amount of work done instead of the
conventionally-used on/off cycle or duty cycle. A DC input Variable
Frequency Drive may be employed in an HVAC system, an irrigation
water pump, or a refrigerator, for example.
[0045] In one embodiment, the application is applied to HVAC
systems on commercial rooftops. Wiring costs and electrical losses
may be reduced by directly feeding the PV power into the HVAC
rooftop compressor or air handling unit. Losses may be further
reduced by utilizing a DC bus to a DC motor.
[0046] The principle of solar synchronized DC loads may be applied
to standardized DC building bus systems (e.g., the emerging 380 VDC
standard). In one embodiment, PV modules may contain DC/DC
converters, with the known inherent benefits of ease of
application, flexibility to modify the system to accommodate
rooftop changes, tolerance to shadowing, etc. Various building
electrical loads may be developed to operate off a standardized
voltage (e.g. 380 VDC), and all loads may be synchronized to PV
output via central control to minimize variation in grid
demand.
[0047] The invention may beneficially influence electricity
consumption via a smart grid. For example, the peak power load and
the peak power generation by the utility company may be reduced by
the invention.
[0048] In another aspect, the invention may realize system
synergies. For example, the invention may enable the coordination
of run times, prevent overloading, and enable the scheduling of
events based on the current weather or forecast (e.g., the amount
of cloud cover).
[0049] In another aspect, the communication between the solar array
and the loads, and the potential communication between the various
loads enabled by the invention may enable the
homeowner/user/operator to locally and remotely control the user
interface. For example, the user may control the user interface
from his couch within the building, from his work place remotely,
or from his vacation home remotely. This local and/or remote user
control may include reviewing performance data, scheduling
operation of appliances based on power cost rates, reviewing
billing, and optimizing operation.
[0050] In another aspect, the invention may include features
utilized by a professional appliance installer. For example, the
installer may be provided with an interface for remotely servicing,
diagnosing, and/or troubleshooting. This interface may eliminate
the need for the installer to make a trip to the job site for
troubleshooting. The interface may also enable the installer to
offer system optimization as a service.
[0051] In still another aspect, the invention may enable an
appliance manufacturer to optimize the appliance or system
remotely. The appliance manufacturer may also remotely diagnose the
appliance or system to thereby assist the installer. The invention
may also enable the appliance manufacturer to monitor the
performance of the appliance or system, as well as monitor the
appliance or system on a long-term basis.
[0052] In a further aspect, the invention may provide a central
user interface in the form of an existing device that is already
familiar to the user, such as an iPhone, television or laptop
computer. By using a familiar interface, the number of questions
from the user is reduced, the number of errors made by the user is
reduced, and the user is enabled to have an intuitive interaction
with the appliance.
[0053] In a still further aspect, the invention may operate with a
universal open source protocol, such as Zigbee, WLAN, etc. Thus,
interaction with other devices may be enabled.
[0054] In another aspect of the invention, there may be a gateway
with firewall in each appliance or device. Thus, a high level of
operational security may be provided.
[0055] In yet another aspect, the invention may be integrated in a
home network. Such home networks may include the Google power meter
or Apple Apps, and/or may be marketed by the Microsoft
HomeStore.
[0056] In a further aspect, the invention may include a parallel DC
network to eliminate DC-to-AC conversion or AC-to-DC conversion.
Thus significant losses caused by such conversions may be
eliminated.
[0057] The invention has been described in some embodiments above
as applying to an HVAC system. However, in other embodiments, the
invention is applied to domestic hot water (DHW), building access
control/alarm systems/security systems/fire alarms, automobile
charging (electric vehicle/plug-in hybrid electric vehicle),
kitchen appliances, media, internet, etc.
[0058] The invention has been described above as applying to a DC
power source in the form of a solar array. However, in other
embodiments, the invention is applied to other sources of DC power,
such as the rectified output of a wind turbine, for example. The
invention may be applied to any DC power source, but may be
particularly applicable to a DC power source whose level of DC
power output fluctuates with time.
[0059] In another embodiment, a bidirectional inverter, similar to
bidirectional inverter 16 in FIG. 1, includes a DC solar variable
frequency drive (VFD) optimizer. This embodiment may be
advantageous with an electric vehicle charger or DC LED lighting
being powered on the bus between the solar PV array and the DC VFD
optimizer. The solar VFD optimizer may remove the need for a solar
inverter and may minimize AC cycling on the utility supply (e.g.,
demand smoothing).
[0060] With a variable frequency drive used in conjunction with an
HVAC, the speed of rotation may be driven by solar radiation. Also,
there may be longer cycles if necessary to offset slower compressor
rotation. Further, this variable frequency drive to HVAC embodiment
may seek constant draw from the utility as opposed to ON/OFF
cycling.
[0061] The solar variable frequency drive (VFD) optimizer may
enable post-installation changes to the solar configuration, and
may enable the use of a high voltage DC power bus, such as could be
used with LED lighting and/or EV changing as mentioned above. Also,
the solar variable frequency drive (VFD) optimizer embodiment may
apply to refrigeration, pumping, etc.
[0062] While this invention has been described as having an
exemplary design, the present invention may be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles.
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