MULTILEVEL POWER CONVERTER AND METHODS OF MANUFACTURING AND OPERATION THEREOF

• US 20130003431A1
• Filed: 06/28/2011
• Published: 01/03/2013
• Est. Priority Date: 06/28/2011
• Status: Active Grant

• Current Assignee: Acleap Power Incorporated
• Original Assignee: General Electric Company
• Inventors: Reddy, Raghothama
• Granted Patent: US 8,792,254 B2
• Time in Patent Office: Days
• US Class Current: 363/126
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/0074 Plural converter units whose inputs are connected in series
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H02M 1/4216 operating from a three-phase input voltage H02M1/4233 takes precedence
• CPC Class Codes: H02M 3/285 Single converters with a plurality of output stages connected in parallel parallel operation of a plurality of converters in dc distribution networks H02J1/10
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A power converter includes an input stage connected to receive a three phase AC input voltage and to provide multiple DC voltage levels. The power converter also includes an output stage of a plurality of interleaved LLC converters having series-connected inputs coupled to the multiple DC voltage levels and parallel-connected outputs to provide a DC output voltage. Additionally, the power converter includes a balancing circuit interconnected to the input and output stages to provide substantially balanced output currents from the plurality of interleaved LLC converters for the DC output voltage. Methods of manufacturing and operating a power converter are also provided.

Claims

1. A power converter, comprising:

an input stage connected to receive a three phase AC input voltage and to provide multiple DC voltage levels;

an output stage of a plurality of interleaved LLC converters having series-connected inputs coupled to the multiple DC voltage levels and parallel-connected outputs to provide a DC output voltage; and

a balancing circuit interconnected to the input and output stages to provide substantially balanced output currents from the plurality of interleaved LLC converters for the DC output voltage.

2. The power converter of claim 1 wherein the balancing circuit includes a balancing capacitor for each of the plurality of interleaved LLC converters.

3. The power converter of claim 1 wherein the balancing circuit includes balancing capacitors that are nominally equal in value.

4. The power converter of claim 1 wherein the balancing circuit includes a bidirectional clamp connected between a junction of two balancing capacitors and one of the multiple DC voltage levels.

5. The power converter of claim 1 wherein the balancing circuit includes (N−

1) balancing capacitors connected to (N−

2) bidirectional clamps for (N−

1) interleaved LLC converters connected to N DC voltage levels, for N equal to at least three.

6. The power converter of claim 5 wherein a nominal phase angle for each control signal of the (N−

1) interleaved LLC converters corresponds to a phase angle of 180°

/(N−

1).

7. The power converter of claim 1 wherein the balancing circuit includes a transorb.

8. The power converter of claim 1 wherein the balancing circuit includes a bidirectional clamp employing one selected from the group consisting of:

a metal oxide varistor;

a resistor or capacitor; and

a MOSFET or a diode.

9. A method of manufacturing a power converter, comprising:

connecting an input stage to receive a three phase AC input voltage and provide multiple DC voltage levels;

constructing an output stage from a plurality of LLC converters having series-connected inputs coupled to the multiple DC voltage levels and parallel-connected outputs to provide a DC output voltage; and

interconnecting a balancing circuit to the input and output stages to substantially balance output currents from the plurality of LLC converters for the DC output voltage.

10. The method of claim 9 wherein the balancing circuit includes a balancing capacitor for each of the plurality of LLC converters.

11. The method of claim 9 wherein the balancing circuit includes balancing capacitors that are nominally equal in value.

12. The method of claim 9 wherein the balancing circuit includes a bidirectional clamp connected between a junction of two balancing capacitors and one of the multiple DC voltage levels.

13. The method of claim 9 wherein the balancing circuit includes (N−

1) balancing capacitors connected to (N−

2) bidirectional clamps for (N−

1) LLC converters connected to N DC voltage levels, for N equal to at least three.

14. The method of claim 13 wherein a nominal phase angle for each control signal of the (N−

1) LLC converters corresponds to a phase angle of 180°

/(N−

1).

15. The method of claim 9 wherein the balancing circuit includes a transorb.

16. The method of claim 9 wherein the balancing circuit includes a bidirectional clamp employing one selected from the group consisting of:

a metal oxide varistor;

a resistor or capacitor; and

a MOSFET or a diode.

17. A method of operating a power converter, comprising:

receiving a three phase AC input voltage and providing multiple DC voltage levels;

generating a DC output voltage from parallel-connected outputs of a plurality of interleaved LLC converters having series-connected inputs coupled to the multiple DC voltage levels; and

providing substantially balanced output currents from the plurality of interleaved LLC converters for the DC output voltage.

18. The method of claim 17 wherein the providing includes providing a balancing capacitor for each of the plurality of interleaved LLC converters.

19. The method of claim 17 wherein the providing includes providing balancing capacitors that are nominally equal in value.

20. The method of claim 17 wherein the providing includes providing bidirectional clamping between a junction of two balancing capacitors and one of the multiple DC voltage levels.

21. The method of claim 17 wherein the providing, for N equal to at least three, includes providing (N−

1) balancing capacitors and (N−

2) bidirectional clamps for (N−

1) interleaved LLC converters and N DC voltage levels.

22. The method of claim 21 wherein a nominal phase angle for each control signal of the (N−

1) interleaved LLC converters corresponds to a phase angle of 180°

/(N−

1).

23. The method of claim 17 wherein the balancing circuit includes a transorb.

24. The method of claim 17 wherein the balancing circuit includes a bidirectional clamp employing one selected from the group consisting of:

a metal oxide varistor;

a resistor or capacitor; and

a MOSFET or a diode.