Apparatus, system, and method for controlling multiple power supplies

• US 7,663,342 B2
• Filed: 01/26/2007
• Issued: 02/16/2010
• Est. Priority Date: 01/26/2007
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Solarbridge Technologies Incorporated (Totalenergies Se)
• Inventors: Kimball, Jonathan W., Krein, Philip T., Benavides, Nicholas D.
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Berhanu; Samuel
• Application Number:
  US11/627,731
• Publication Number:
  US 20080179961A1
• Time in Patent Office: 1,117 Days
• Field of Search: 320/132, 324/427, 307 55- 58
• US Class Current: 320/132
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems

Abstract

In an electrical power supply having a plurality of switching power converter circuits and configured to supply a voltage to an electrical load, a method of controlling a duty cycle of at least one switch of one of the plurality of switching power converter circuits includes determining a storage voltage produced by the one of the plurality of energy storage devices. The method further includes determining an average storage voltage corresponding to an average of storage voltages produced by each of the plurality of energy storage devices. The method further includes determining at least one control signal as a function of the storage voltage, the average storage voltage, and a reference voltage. The method further includes controlling the duty cycle of the at least one switch of the one of the plurality of switching power converter circuits based upon the at least one control signal.

Claims

1. In an electrical power supply having a plurality of switching power converter circuits and configured to supply a voltage to an electrical load, a method of controlling a duty cycle of at least one switch of one of the plurality of switching power converter circuits comprising:

determining a storage voltage produced by one of a plurality of energy storage devices,

determining an average storage voltage corresponding to an average of storage voltages produced by each of the plurality of energy storage devices,

determining at least one control signal as a function of the storage voltage, the average storage voltage, and a reference voltage, and

controlling the duty cycle of the at least one switch of the one of the plurality of switching power converter circuits based upon the at least one control signal.

2. The method of claim 1, wherein the determining at least one control signal comprises determining at least one control signal as a function of a predetermined upper limit when the average storage voltage is greater than the predetermined upper limit and as a function of a lower predetermined limit when the average storage voltage is less than the predetermined lower limit.

3. The method of claim 2, wherein the predetermined upper limit and the predetermined lower limit are based upon the storage voltage.

4. The method of claim 1, wherein the determining an average storage voltage comprises determining the voltage at an electrical node that is electrically connected to an output terminal of each of the plurality of energy storage devices through a respective resistive element.

5. The method of claim 1, wherein the determining at least one control signal comprises determining at least one control signal as a function of power losses associated with the at least one switch of the one of the plurality of switching power converter circuits.

6. The method of claim 5, wherein the at least one switch comprises a first and second switch, and

wherein, the controlling the duty cycle comprises controlling the duty cycle of the first switch of the one of the plurality of switching power converters according to the equation:

D=k∫

(V_sh,cl−

q₁V_sw−

q₂V_ref*)dt,

wherein;

D is the duty cycle of the first switch, k is a predetermined constant, V_sh,cl is the average storage voltage bounded by a predetermined upper and lower limit, q₁ is the logic state of the first switch, V_sw is the voltage associated with the power losses of the first switch of each of the plurality of switching power converter circuits, q₂ is the logic state of the second switch, and V_ref* is the reference voltage.

7. The method of claim 1, further comprising determining an output current signal of the one of the plurality of energy storage devices, and

wherein, the determining at least one control signal comprises determining the at least one control signal of the at least one switch based upon the output current signal.

8. An electrical power supply configured to supply a voltage to an electrical load, the power supply comprising:

a first energy storage device,

a switching power converter circuit having a first input configured to receive a control signal and a second input configured to receive a first storage voltage produced by the first energy storage device, the switching power converter circuit configured to produce the voltage supplied to the electrical load based on the first storage voltage and having a duty cycle defined by the control signal, and

a controller having a first input configured to receive the first storage voltage, a second input configured to receive an average voltage corresponding to an average of storage voltages produced by a number of other energy storage devices and the first storage voltage, and a third input configured to receive a reference voltage, the controller configured to produce the first control signal as a function of the first storage voltage, the average voltage, and the reference voltage.

9. The power supply of claim 8, wherein the first energy storage device comprises a number of ultracapacitors and each of the number of other energy storage devices comprises a number of ultracapacitors.

10. The power supply of claim 8, wherein the first energy storage device comprises a number of rechargeable batteries and each of the number of other energy storage devices comprises a number of rechargeable batteries.

11. The power supply of claim 8, wherein:

the controller has a fourth input configured to receive the output current from the first energy storage device, and

the controller is further configured to produce the first control signal as a function of the output current.

12. The power supply of claim 8, wherein the controller is configured to limit the average voltage between an upper limit and a lower limit, and

wherein the upper and lower limits are each based upon the first storage voltage.

13. The power supply of claim 8, wherein:

the a switching power converter circuit further includes at least one switch, and

the controller is further configured to produce the first control signal as a function of the power losses associated with the at least one switch.

14. The power supply of claim 8, wherein the switching power converter circuit is configured to conduct energy bidirectionally.

15. The power supply of claim 8, wherein the switching power converter circuit is configured to conduct energy unidirectionally.

16. The power supply of claim 8, wherein the average voltage comprises the voltage at an electrical node being electrically connected through separate resistive elements to an output terminal of the first energy storage device and an output terminal of each of the number of other energy storage devices.

17. The power supply of claim 8, wherein the reference voltage is an average voltage of a plurality of reference voltages.

18. The power supply of claim 8, wherein the switching power converter circuit is a boost converter circuit.

19. The power supply of claim 8, wherein the switching power converter circuit is a buck converter circuit.

20. The power supply of claim 8, wherein the switching power converter circuit is a push-pull converter circuit.

21. The power supply of claim 8, wherein the at least one switch is a MOSFET.

22. A power supply system comprising:

a plurality of power supplies each including a first and second output terminal, wherein;

the first output terminals of each of the plurality of power supplies are electrically connected to one another and the second output terminals of each of the plurality of power supplies are electrically connected to one another, and

each of the plurality of power supplies includes an energy storage device configured to produce a storage voltage, each energy storage device being electrically connected to a common electrical node through a separate resistive element, wherein the voltage at the electrical node is an average voltage of the storage voltages produced by each of the energy storage devices, and

each of the plurality of power supplies further includes;

a switching power converter circuit having a first input configured to receive a control signal and a second input configured to receive the storage voltage produced by the energy storage device, the switching power converter circuit configured to produce an output voltage across the first and second output terminals and having a duty cycle defined by the control signal, and

a controller having a first input configured to receive the storage voltage, a second input configured to receive the average voltage, and a third input configured to receive a reference voltage, the controller configured to produce the control signal based upon the storage voltage, the average voltage, and a reference voltage.