WO2016033597A1 - Intelligent load switch for solar electric system and method of using the same - Google Patents

Abstract

Disclosed are apparatuses, systems and methods for prioritizing loads of an off-grid power supply network to conserve power resources. The off-grid power supply network includes remote sensors, a plurality of power sources and a plurality of loads. According to some embodiments, the system comprises an inverter connected to one of the plurality of the power sources and an intelligent load switch connected to the inverter and the plurality of loads. The output of the one of the plurality of the power sources is input to the inverter. The intelligent switch takes output of the inverter as input, and generates output that drives the plurality of loads in response to feedback and status of the plurality of power sources and the plurality of loads.

Description

INTELLIGENT LOAD SWITCH FOR SOLAR ELECTRIC SYSTEM

AND METHOD OF USING THE SAME

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit under 35 USC 119(e) of prior co-pending U.S.

Provisional Patent Application Serial No. 62/044,115, filed August 29, 2014, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE ART

[0002] The disclosure relates generally to an intelligent load switching apparatus and methods. In particular, this disclosure is directed to apparatus and methods for making intelligent conservation decisions and lowering overall cost of an off-grid power system.

BACKGROUND

[0003] Off grid power applications often require different types of inverters to drive different types of loads. Specialty pump inverters are generally very effective for driving 3- phase pumps using variable frequency drive (VFD) techniques. Other inverters output "pure sine" AC voltages at a fixed frequency for household loads such as lights, televisions and computers. Using multiple inverters usually requires multiple separate power sources, such as multiple different solar arrays.

[0004] Additionally, while desirable to prioritize loads in order to conserve critical resources such as battery power, the conventional systems lacks the capability to prioritize loads in conjunction with off grid power applications. A solution is needed to prioritize loads to intelligently conserve critical off-grid energy resources and lower the overall system cost. SUMMARY

[0005] Described is an integrated device that is a component in a larger off-grid electric system, such as solar, that serves to lower the overall system cost and make intelligent conservation decisions when the off-grid energy resources are limited, and methods related thereto.

[0006] In a preferred embodiment is described an intelligent load switching apparatus that is preferably a component of an off- grid electric system, and methods of using the same.

[0007] In a particularly preferred embodiment the intelligent load switching apparatus addresses both the adaptation of loads with different electrical requirements as well as the conservation of energy by making intelligent switching decisions through the use of a policy engine.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the disclosure in conjunction with the accompanying figures, wherein:

[0009] FIG. 1 illustrates a high level drawing of an example system for intelligent load switching according to one embodiment of the present disclosure.

[0010] FIG. 2 illustrates a block diagram of a switch according to one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] This specification discloses one or more embodiments that incorporate the features of this disclosure. The disclosed embodiment(s) merely exemplify the inventive concepts. The scope of the disclosure is not limited to the disclosed embodiment(s). The disclosure is defined by the claims appended hereto. The embodiment(s) described, and references in the specification to "one embodiment", "an embodiment", "an example

embodiment", etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0012] Embodiments of the disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the disclosure may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc.

[0013] As described above, off grid energy applications, particularly solar applications, often require different types of inverters to drive different types of loads. It has been recognized herein that using multiple inverters usually requires multiple separate solar arrays, thus making it very inefficient to share resources and adding significant cost to the overall system. As such, combining multiple types of outputs in a flexible configuration within a single device, as described herein, will add significant functionality to systems that otherwise would not exist, and will also drive down overall system cost and size.

[0014] Additionally, the apparatus and methods described herein also advantageously allow for the prioritization of loads, including to conserve critical resources such as battery power as noted above. For example, in a solar power system with fixed storage, many consecutive days of inclement weather can limit the ability to charge batteries, and the apparatus and methods described herein allow for the prioritization and scheduling of critical loads in order to conserve energy. The intelligence to determine when certain loads can be switched off and on is driven by a software policy engine, further described herein, which uses a combination of heuristics, predictive analysis and human input to determine the policies.

[0015] FIG 1 illustrates a high level drawing of the system in which an embodiment according to the disclosure works.

[0016] As shown, a single inverter (1) is used to convert a PV array to AC voltage, which is then fed into the intelligent load switch (1 A). Here, the single inverter (1) provides the Maximum Power Point Tracking (MPPT) control of the solar array and provides a single AC output, which is used as the main source of power for the switch (1 A).

[0017] Typically, backup batteries are used for AC backup: they get charged from the solar array using a build-in charge controller in the inverter (1), and then drains at night when no PV is available. In some embodiments, the DC of the battery bank also goes directly into the load switch (1 A).

[0018] As shown, in addition to the AC from the PV array, the switch (1 A) takes grid AC input and external DC input from the battery bank (shown in FIG. 1) directly.

[0019] Most conventional inverters provide a single AC output, and this output is usually fixed at one voltage, frequency or phase. Here, as shown in FIG. 1, the load switch (1 A) generates multiple outputs: output 2, outputs 3 and output 4.

[0020] In some embodiments, one of the outputs (output 2) of the switch (1 A) is configured to be a Sinusoidal Pulse Width Modulation (SPWM) output so as to drive a VFD pump. This output 2 is typically scheduled to run only during the day when more solar energy is available according to a priority policy as discussed further below.

[0021] In some embodiments, the three outputs (3) of the switch (1 A) feed a home. Each output (3) is pure sine, fixed frequency, and attached to a circuit breaker at the electrical panel on the side of the house. These outputs (3) are prioritized by the policy engine in the switch (1 A) as described further below. As an example, the refrigerator circuit may be prioritized ahead of the circuit with the TV if the available power is limited.

[0022] In some embodiments, another output (4) of the switch load (1 A) regulates DC to a desired voltage and drives LED loads. [0023] FIG. 2 shows a block diagram of the load switch (1 A), attached to the inverter (1).

In some embodiments, the inverter (1) is integrated within the load switch (1A).

[0024] As shown in FIG. 2, the switch 1 A includes a voltage and frequency signal conditioning circuit 10, a phase converter 20, a DC/DC conversion circuit 30, each of which receives various power inputs, including DC from a PV/battery as shown, AC power from the inverter (1) as shown, and power from the grid (not shown). In addition, each of the voltage and frequency signal conditioning circuit 10, the phase converter 20, and the DC/DC conversion circuit 30 is controlled using control signals obtained from the configuration control output 52, which is part of the policy engine 50, described hereinafter.

[0025] Also shown in FIG. 2 is the power switching circuit 40, which receives outputs from each of the voltage and frequency signal conditioning circuit 10, the phase converter 20, and the DC/DC conversion circuit 30. In addition, the switching circuit 40 is controlled using switch control signals obtained from the switching scheduling output 54, which is part of the policy engine 50, described hereinafter.

[0026] In addition, the policy engine 50 takes as input feedback from the switching circuit to determine whether the current configuration and prioritization is appropriate or should be changed. The feedback is preferably in the form of parameters such as voltage, frequency, and current. Of these feedback signals, current is most significant as it provides data relative to the amount of power that is being consumed (i.e. "consumption information") to the policy engine 50, which is invaluable for keeping track of the finite resources such as the battery life of the backup battery bank as shown in FIG. 1.

[0027] In some embodiments, monitoring of the switching circuit 40 takes place using either the same feedback that is reported to the policy engine 50. In some embodiments, further analysis of the feedback is performed externally and the resulting analysis data is then provided to the policy engine 50 or mobile applications through the communication module 60.

[0028] In many instances, the monitoring information of most significance is information that might trigger an alarm, such as which outputs are active, disabled or being stressed. The monitoring information is then communicated to the communication module 60, for use in providing external notifications of status, among others. [0029] Further, external policies can be formed and provided to the policy engine 50 through the communication module 60, either based upon the monitoring information provided or based upon other requests, using a comiection 62, which can be wired and/or wireless (and WIFI and Bluetooth being shown).

[0030] The policy engine 50 is designed to control the behavior of the load switch 1 A based on a series of inputs, where the inputs are specified by the user, remote sensors, or other external sources such as GPS, weather station data or real time clock information.

[0031] A simple embodiment to implement the policy engine 50 includes the use of a timer that switches an output on or off based on the time of day. For example:

1) Keep Output #1 on at all times.

2) Switch Output #2 off between 11PM and 6AM on Monday through Friday.

[0032] However, a preferred embodiment of the policy engine 50, as illustrated above, is to make intelligent decisions based on a number of factors, using a combination oftiistorical, real time, and predictive data, an a manner that is configurable and changeable over time, including based upon data from remote sensors that are read by remote sensor logic 56 as well as real time clock data and GPS data that can be obtained using real time clock and GPS block 58. Such an embodiment is preferably implemented using a processor, memory and control block 51, as shown, that also may include other components that are conventionally used in computer systems, so as to run an application program contained in programmed software instructions, as is conventionally known, in order to implement the various features described herein, and allow changes to be made based on changes to settings within the applications software and/or updates to the application software, as shown by the descriptions herein, thereby ultimately providing the signals to the configuration control output 52 and the switching scheduling output 54, as shown.

[0033] A more complex example of how the policy engine 50 may be used to make a switching decision is provided below:

[0034] A user is utilizing the Intelligent Load Switch (ILS) according to the present disclosure in an off-grid solar system, which has enough capacity during a sunny day to fully charge a battery bank and still provide power to the loads. The system is wired to feed critical loads, such as their refrigerator and their emergency lighting, from output #1 of the load switch. They are feeding the rest of their home through output #2 of the load switch. Using a GUI interface and configuration wizard associated with the policy engine 50, they have configured the policy engine 50 with the following logic:

1) Enable Outputs #1 and #2 at 120V AC, 60Hz.

2) If the sensor that monitors current from the charge controller senses that the batteries have been draining more than expected for several days in a row, issue an e-mail alarm to the system owner to allow manual intervention on the loading, such as adjusting the temperature in the home to use less air conditioning. In some implementations, the charge controller is part of the inverter that is external to the load switch. It is noted that the sensor may be part of the remote sensors (as shown in FIG.2) and implemented as a simple data interface (wired or wireless).

3) If the backup batteries continue to drain, and another sensor such as a weather station predicts cloudy weather for the next few days, issue another warning and begin to cycle Output #2 off from 1 1PM to 6 AM, or a time preset by the user as "low battery mitigation policy" to save battery power.

4) As the daily battery levels become even worse the system may invoke another predefined policy named "critical battery level policy" that turns off Output #2 entirely and starts to cycle Output #1 off for 20 minutes every hour between 12AM and 7AM.

5) As the system predicts recovery of the battery capacity due to better weather, the policies will eventually return to a normal state.

6) E-mail or SMS is sent to the system owner each time one of the predefined policies is invoked, including information on what caused the change in state. Warnings could also be sent in advance to allow a system owner to override a possible state change.

[0035] As is evident, the system provides a robust method of controlling multiple different power outputs, based upon a policy engine 50 that is preferably programmable and configurable, and related components as described.

[0036] Although the present invention has been particularly described with reference to embodiments thereof, it should be readily apparent to those of ordinary skill in the art that various changes, modifications and substitutes are intended within the form and details thereof, without departing from the spirit and scope of the invention. Accordingly, it will be appreciated that in numerous instances some features of the invention will be employed without a corresponding use of other features. Further, those skilled in the art will understand that variations can be made in the number and arrangement of components illustrated in the above figures.

Claims

What is claimed is:

1. A system for intelligently switching load of an off-grid power supply network, the off- grid power supply network including a plurality of power sources and a plurality of loads, the system comprising:

an inverter connected to one of the plurality of the power sources, wherein the output of the one of the plurality of the power sources is input to the inverter; and

an intelligent switch connected to the inverter and the plurality of loads, wherein the intelligent switch takes output of the inverter as input, and generates output that drives the plurality of loads in response to feedback and status of the plurality of power sources and the plurality of loads.

2. An apparatus for intelligently switching load of an off- grid power supply network,

wherein the off-grid power supply network includes an inverter and remote sensors and is connected to a plurality of power consumption entities, the apparatus comprising:

an input processing circuit, wherein the input processing circuit receives various power inputs;

a switching circuit, wherein the switching circuit receives output from the input processing circuit and generates a plurality of power output signals according to switching control signals, and

a policy engine, wherein the policy engine generates the switching control signals using a combination of historical, real time and predictive data in a manner that is configurable and changeable over time.

3. The apparatus of claim 2, wherein the various power inputs comprise AC power from the inverter, grid AC power and DC power from PV/Battery.

4. The apparatus of claim 3, wherein the inverter is capable of converting a PV array to AC power.

5. The apparatus of claim 3, wherein the AC power has a fixed voltage, frequency or phase.

6. The apparatus of claim 3, wherein the inverter is capable of performing Maximum Power Point Tracking.

7. The apparatus of claim 2, wherein the input processing circuit comprises a voltage and frequency signal conditioning circuit, a phase converter, and a DC to DC conversion circuit.

8. The apparatus of claim 2, wherein the policy engine comprises a processor, an output configuration controller, a switching scheduling controller, a remote sensor logic, and a timing control circuit.

9. The apparatus of claim 2, wherein the policy engine generates the switching control signals based in part on input from the remote sensors and feedback from the switching circuit.

10. The apparatus of claim 3, wherein at least one of the remote sensors is capable of sensing the drainage of batteries of the PV/Battery.

11. The apparatus of claim 2, wherein the plurality of power output signals comprise one or more power output signals that are pure sine signals with a fixed frequency.

12. The apparatus of claim 2, wherein the plurality of power output signals comprise a power output signal that is a sinusoidal pulse width modulated signal.

13. The apparatus of claim 2, wherein the policy engine prioritizes the plurality of power output signals based on availability of the various power inputs.

14. The system of claim 1, further comprises a communication module, wherein the

communication module is capable of sending warning messages in advance.

15. A method for prioritizing loads of an off- grid power supply network to conserve power resources, the off-grid power supply network including remote sensors, a plurality of power sources and a plurality of loads, the method comprising:

receiving various power inputs from the plurality of power sources;

processing the various power inputs according to configuration control signals; and

generating a plurality of power output signals from the processed various power inputs according to switching scheduling control signals,

wherein the configuration control signals and the switching scheduling control signals are generated using a combination of historical, real time and predictive data in a manner that is configurable and changeable over time.

16. The method of claim 15, wherein the various power inputs comprise AC power from an inverter, grid AC power and DC power from PV/Battery.

17. The method of claim 16, wherein the inverter is capable of converting a PV array to AC power.

18. The method of claim 16, wherein the AC power has a fixed voltage, frequency or phase.

19. The method of claim 16, the inverter is capable of performing Maximum Power Point Tracking.

20. The method of claim 15, wherein the processing comprises conditioning voltage and frequency of the various power inputs.

21. The method of claim 15, wherein the switching scheduling control signals are generated based in part on input from one or more of the remote sensors and feedback from the switching circuit.

22. The method of claim 15, further comprising sending warning messages regarding the plurality of loads in advance.

23. The method of claim 15, further comprising prioritizing the plurality of power output signals based on availability of the various power inputs.