Feedback control for parallel power converter synchronization

Patent metadata

Field	Value
Publication number	US-10291111-B1
Application number	US-201815934244-A
Country	US
Kind code	B1
Filing date	Mar 23, 2018
Priority date	Mar 23, 2018
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

A system and method includes parallel power converters, at least one current sensor, and a first feedback control circuit. A first power converter is configured to convert a first input power to a first output power, and is controlled using pulse width modulation having a first switching period. One or more second power converters are connected in parallel with the first power converter and configured to convert a second input power to a second output power. The first output power and the second output power are provided to a load. The at least one current sensor is positioned to sense first output current of the first output power, and the first feedback control circuit is configured to calculate a first metric based on the first sensed current at each of a plurality of first edges of each half switching period of the first switching period, and at intermediate points between each of the plurality of first edges. The first feedback control circuit is configured to adjust the first switching period based upon the first metric.

First claim

The invention claimed is:

1. A system comprising:
a first power converter configured to convert a first input power to a first output power, wherein the first power converter is controlled using pulse width modulation having a first switching period;
one or more second power converters connected in parallel with the first power converter and configured to convert a second input power to a second output power, wherein the first output power and the second output power are provided to a load;
at least one current sensor positioned to sense first output current of the first output power; and
a first feedback control circuit configured to calculate a first metric based on the first sensed current at each of a plurality of first edges of each half switching period of the first switching period, and at an intermediate point between each of the plurality of first edges;
wherein the first feedback control circuit is configured to adjust the first switching period based upon the first metric and the first power converter is further controlled using a first carrier wave, and wherein the plurality of first edges are upper and lower bounds of the first carrier wave.

2. The system of claim 1 , wherein one of the one or more second power converters is controlled using pulse width modulation having a second switching period, and wherein the system further comprises:
at least one second current sensor positioned to sense second output current of the second output power; and
a second feedback control circuit configured to calculate a second metric based on the second sensed current at each of a plurality of second edges of each half switching period of the second switching period, and at intermediate points between each of the plurality of second edges.

3. The system of claim 2 , wherein the second feedback control circuit is configured to adjust the second switching period based upon the second metric.

4. The system of claim 3 , wherein the first metric is based further upon an average of a sign of a duty cycle of the pulse width modulation of the first output current multiplied by the difference between the first sensed current at each of the plurality of first edges and the intermediate points between each of the plurality of first edges.

5. The system of claim 3 , wherein the first current metric is a root mean square of the difference between the first sensed current at each of the plurality of first edges and the intermediate points between each of the plurality of first edges.

6. The system of claim 3 , wherein the first feedback control circuit employs a proportional gain for adjusting the first switching period.

7. The system of claim 2 , further comprising:
a synchronization circuit configured to calculate a metric difference between the first metric and the second metric, and wherein the first feedback control circuit is configured to adjust the first or the second switching period based further upon the metric difference.

8. The system of claim 7 , wherein the first current metric is a root mean square of the first sensed current at each of the plurality of intermediate points between each of the plurality of first edges and the second metric is a root mean square of the second current sampled at the intermediate points between each of the plurality of second edges.

9. The system of claim 7 , wherein the first current metric is based upon an average of the first sensed current at each of the intermediate points between each of the plurality of first edges and the second metric is an average of the second current sampled at the intermediate points between each of the plurality of second edges.

10. The system of claim 1 , wherein the first input power is direct current power and wherein the first output power is three-phase alternating current power having three output phases.

11. The system of claim 10 , wherein the first feedback control circuit is configured to calculate the first metric based on the first sensed current of only one of the three output phases.

12. The system of claim 1 , wherein the first input power is direct current power and the first output power is single-phase alternating current power.

13. A method of controlling parallel power converters, the method comprising:
sensing a first output current of a first one of the parallel power converters as first edge sensed current, wherein the first one of the parallel power converters is controlled using pulse width modulation generated using a carrier wave and having a first switching period, and wherein the first edge sensed current is the first output current at each of a plurality of first edges of each half switching period of the first switching period, wherein the plurality of first edges are upper and lower bounds of the carrier wave;
sensing the first output current of the first one of the parallel power converters as first intermediate sensed current at a point between each of the plurality of first edges;
determining a first current metric based on the first edge sensed current and the first intermediate sensed current; and
adjusting the first switching period based on the first current metric.

14. The method of claim 13 , further comprising:
sensing a second output current of a second one of the parallel power converters as second edge sensed, wherein the second one of the parallel power converters is controlled using pulse width modulation having a second switching period, and wherein the second edge sensed current is the second output current at each of a plurality of second edges of each half switching period of the second switching period;
sensing the second output current of the second one of the parallel power converters as second intermediate sensed current at a point between each of the plurality of second edges; and
determining a second current metric based on the second edge sensed current and the second intermediate sensed current.

15. The method of claim 14 , further comprising adjusting the second switching period based on the second current metric.

16. The method of claim 15 , wherein adjusting the first and second switching periods comprises:
generating a first synchronization signal based on the first current metric;
providing the first synchronization signal to the first one of the plurality of parallel converters;
adjusting the first switching period using the first synchronization signal;
generating a second synchronization signal based on the second current metric;
providing the second synchronization signal to the second one of the plurality of parallel converters; and
adjusting the second switching period using the second synchronization signal.

17. The method of claim 14 , wherein adjusting the first switching period based on the first current metric comprises:
calculating a metric difference between the first current metric and the second current metric; and
adjusting the first switching period based on the metric difference.

18. The method of claim 13 , wherein determining the first current metric based on the first edge sensed current and the first intermediate sensed current comprises:
calculating a difference between the first edge sensed current and the first intermediate sensed current;
multiplying the difference by a sign of a duty cycle of the pulse width modulation of the first output current to obtain a multiplied output; and
determining an average of the multiplied output over a period of the output current to obtain the first current metric.

19. A method of controlling a plurality of parallel power co

Assignees

• Hamilton Sundstrand Corp

Inventors

• Rosado Sebastian
• Valdivia Guerrero Virgilio
• Albiol-Tendillo Laura

Classifications

• H02M3/285

  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 title

• H02M5/44

  using discharge tubes or semiconductor devices to convert the intermediate DC into AC · CPC title

• H02M1/10 Primary

  Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from AC or DC · CPC title

• H02M7/493 Primary

  the static converters being arranged for operation in parallel · CPC title

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title