System and method for bidirectional DC-AC power conversion

• US 8,698,354 B2
• Filed: 11/05/2010
• Issued: 04/15/2014
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Inventors: Ghosh, Rajesh, Lipare, Mahesh, Klikic, Damir, Narasimha, Raju
• Primary Examiner(s): AMAYA, CARLOS DAVID
• Application Number:
  US12/940,100
• Publication Number:
  US 20120112547A1
• Time in Patent Office: 1,257 Days
• Field of Search: 307/64, 307/66, 307/82
• US Class Current: 307/66
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 3/33553 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: H02M 3/33584 Bidirectional converters

Abstract

A power converter includes a power input configured to receive input power from an AC power source, a power output configured to provide output power to a load, a battery interface configured to exchange DC power with a battery, and power converter circuitry. The power converter circuitry is adapted to, in a first interconnection configuration, convert the input power into the DC power at the battery interface, and, in a second interconnection configuration, convert the DC power at the battery interface into the output power. The power converter circuitry has a power line, a transformer, a first connection node switchably connected to the power line in the first interconnection configuration and switchably connected to the transformer in the second interconnection configuration, and a second connection node switchably connected to the transformer in the first interconnection configuration and switchably connected to the power line in the second interconnection configuration.

Claims

1. A power converter, comprising:

a power input configured to receive input power from an AC power source;

a power output configured to provide output power to a load;

a battery interface configured to exchange DC power with a battery; and

power converter circuitry coupled to the power input, the power output, and the battery interface, the power converter circuitry adapted to, in a first interconnection configuration, convert the input power into the DC power at the battery interface, and further adapted to, in a second interconnection configuration, convert the DC power at the battery interface into the output power, the power converter circuitry having;

a power line coupled to at least one of the power input and the power output;

a transformer;

a first connection node switchably connected to the power line in the first interconnection configuration and switchably connected to the transformer in the second interconnection configuration; and

a second connection node switchably connected to the transformer in the first interconnection configuration and switchably connected to the power line in the second interconnection configuration.

2. The power converter of claim 1, wherein the power converter circuitry includes a relay coupled to the first connection node, the second connection node, the power line and the transformer for interconnecting the first connection node, the second connection node, the power line and the transformer into one of the first interconnection configuration and the second interconnection configuration.

3. The power converter of claim 1, further comprising a controller coupled to the power converter circuitry and configured to select one of the first interconnection configuration and the second interconnection configuration based upon the input power received at the power input.

4. The power converter of claim 1, wherein the first interconnection configuration of the power converter circuitry includes a boost converter.

5. The power converter of claim 1, wherein the second interconnection configuration of the power converter circuitry includes an inverter.

6. The power converter of claim 5, wherein the inverter includes a plurality of switching devices configured in one of a full-bridge configuration and a half-bridge configuration.

7. The power converter of claim 1, wherein the power converter circuit includes a DC-to-DC converter configured as one of a full-bridge converter and a push-pull converter.

8. The power converter of claim 7, wherein the DC-to-DC converter includes a series resonant power converter.

9. The power converter of claim 8, wherein the DC-to-DC converter includes a high-frequency transformer.

10. The power converter of claim 1, further comprising the battery coupled to the battery interface.

11. The power converter of claim 10, wherein the power converter is included in an uninterruptible power supply.

12. The power converter of claim 1, wherein the transformer has a first tap and a second tap, wherein the first connection node is switchably connected to the first tap of the transformer in the second interconnection configuration, and wherein the second connection node is switchably connected to the second tap of the transformer in the first interconnection configuration.

13. A method of converting power in an uninterruptible power supply, the method comprising:

connecting, in a first mode of operation, a first connection node of a power conversion circuit to an AC power source;

connecting, in the first mode of operation, a second connection node of the power conversion circuit to a transformer;

receiving, in the first mode of operation, input power from the AC power source;

converting the input power into DC power during the first mode of operation;

connecting, in a second mode of operation, the first connection node to the transformer;

connecting, in the second mode of operation, the second connection node to a load;

receiving, in the second mode of operation, the DC power from a DC power source; and

converting the DC power into output power during the second mode of operation.

14. The method of claim 13, wherein the power conversion circuit includes a plurality of switching devices, and wherein the method further comprises operating, in the first mode of operation, the plurality of switching devices with a square wave pulse width modulated signal to convert the input power into a high-voltage DC power.

15. The method of claim 14, wherein the plurality of switching devices is a first plurality of switching devices, wherein the power conversion circuit further includes a second plurality of switching devices, and wherein the method further comprises operating, in the first mode of operation, the second plurality of switching devices in synchronization with the first plurality of switching devices to convert the high-voltage DC power into the DC power.

16. The method of claim 15, wherein the uninterruptible power supply includes a boost converter, and wherein the method further comprises regulating, in the first mode of operation, a battery charging current of the uninterruptible power supply by operating the first plurality of switching devices and the second plurality of switching devices with a pulse width modulated signal having a duty cycle of 50%, and adjusting, in the first mode of operation, a switching frequency of the boost converter.

17. The method of claim 15, wherein the uninterruptible power supply includes a series resonant DC to DC converter, and wherein the method further comprises regulating, in the first mode of operation, a battery charging current of the uninterruptible power supply by operating the first plurality of switching devices and the second plurality of switching devices with a pulse width modulated signal having a duty cycle of less than 50%, and adjusting, in the first mode of operation, a resonance link current of the series resonant DC to DC converter by varying the duty cycle of the pulse width modulated signal.

18. The method of claim 13, wherein the uninterruptible power supply includes a series resonant DC to DC converter, wherein the power conversion circuit includes a plurality of switching devices, and wherein the method further comprises operating, in the second mode of operation, the plurality of switching devices with a pulse width modulated signal having a duty cycle of 50% and further having a frequency approximately equal to a resonance frequency of the series resonant DC to DC converter to convert the DC power into a high-voltage DC power.

19. A power converter, comprising:

a power input configured to receive an input power from a power source;

a power output configured to provide an output power to a load;

a battery interface configured to exchange a battery power with a battery;

a power converter circuit coupled to the power input, the power output, and the battery interface, the power converter circuit including a transformer, a plurality of selectively interconnectable electrical components, a first connection node disposed between at least two of the plurality of selectively interconnectable electrical components and switchably coupled to one of the power input and the transformer, and a second connection node disposed between at least two others of the plurality of selectively interconnectable electrical components and switchably coupled to one of the power input and the transformer; and

means for selectively configuring an interconnection of the plurality of electrical components into one of a first interconnection configuration for converting the input power into the battery power and a second interconnection configuration for converting the battery power into the output power, the second interconnection configuration having a different interconnection of the plurality of electrical components than the first interconnection configuration.

20. The power converter of claim 19, wherein the plurality of electrical components, in the first interconnection configuration, includes a boost converter, and wherein the plurality of electrical components, in the second interconnection configuration, includes an inverter.