Power converter protection circuit

Patent metadata

Field	Value
Publication number	US-11456677-B2
Application number	US-202017117603-A
Country	US
Kind code	B2
Filing date	Dec 10, 2020
Priority date	Dec 10, 2020
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

A power conversion system includes a first switch configured to be connected between a first phase of a polyphase alternating current (AC) power source and an electrical load and a first diode configured to be connected between the first phase of the polyphase AC power source and the electrical load, the diode configured to conduct a current from the AC power source to the electrical load. The power conversion system also includes a control unit configured to interface with the first switch to close, responsive to the occurrence of a short circuit fault, the first switch during a negative current portion of the AC cycle of the first phase of the polyphase AC power source and open, responsive to the occurrence of the short circuit fault, the first switch during a positive current portion of the AC cycle of the first phase of the polyphase AC power source.

First claim

The invention claimed is:

1. A power conversion system comprising:
a first switch configured to be connected between a first phase of a polyphase alternating current (AC) power source and an electrical load;
a first diode configured to be connected between the first phase of the polyphase AC power source and the electrical load, wherein the diode is configured to conduct a current from the first phase of the polyphase AC power source to the electrical load; and
a control unit configured to interface with the first switch to close, responsive to the occurrence of a short circuit fault, the first switch during a negative current portion of the AC cycle of the first phase of the polyphase AC power source and open, responsive to the occurrence of the short circuit fault, the first switch during a positive current portion of the AC cycle of the first phase of the polyphase AC power source.

2. The power conversion system of claim 1 , further comprising:
a second switch configured to be connected between a second phase of the polyphase AC power source and the electrical load;
a second diode configured to be connected between the second phase of the polyphase AC power source and the electrical load, wherein the diode is configured to conduct a current from the second phase of the polyphase AC power source to the electrical load;
a third switch configured to be connected between a third phase of the polyphase AC power source and the electrical load; and
a third diode configured to be connected between the third phase of the polyphase AC power source and the electrical load, wherein the diode is configured to conduct a current from the third phase of the polyphase AC power source to the electrical load,
wherein the control unit is configured to interface with the second switch to close, responsive to the occurrence of the short circuit fault, the second switch during a negative current portion of the AC cycle of the second phase of the polyphase AC power source and open, responsive to the occurrence of the short circuit fault, the second switch during a positive current portion of the AC cycle of the second phase of the polyphase AC power source,
wherein the control unit is configured to interface with the third switch to close, responsive to the occurrence of the short circuit fault, the third switch during a negative current portion of the AC cycle of the third phase of the polyphase AC power source and open, responsive to the occurrence of the short circuit fault, the third switch during a positive current portion of the AC cycle of the third phase of the polyphase AC power source.

3. The power conversion system of claim 2 , wherein each of the first, second, and third phases of the polyphase AC power source are configured to output AC that is 120 degrees out of phase with each of the other phases.

4. The power conversion system of claim 3 , wherein each of the first, second, and third switches and each of the first, second, and third diodes are configured to be high-side connected between the polyphase AC power source and the electrical load.

5. The power conversion system of claim 1 , further comprising:
a first low-side switch configured to be connected between the first phase of the polyphase AC power source and the electrical load; and
a first low-side diode configured to be connected between the first phase of the polyphase AC power source and the electrical load, wherein the diode is configured to conduct a current from the electrical load to the first phase of the polyphase AC power source,
wherein the control unit configured to interface with the first switch to, responsive to the occurrence of the short circuit fault, close the first switch and open the first low-side switch for a first amount of time and open the first switch and close the first low-side switch for a second amount of time, wherein the first and second amounts of time occur during different periods of time.

6. The power conversion system of claim 5 , wherein the first and second amounts of time comprise at least one AC cycle of the first phase of the polyphase AC power source.

7. The power conversion system of claim 6 , wherein the control unit configured to interface with the first switch to close, responsive to the occurrence of the short circuit fault, the first switch during a negative current portion of the AC cycle of the first phase of the polyphase AC power source and open, responsive to the occurrence of the short circuit fault, the first switch during a positive current portion of the AC cycle of the first phase of the polyphase AC power source during the first amount of time,
wherein the control unit configured to interface with the first low-side switch to close, responsive to the occurrence of the short circuit fault, the first low-side switch during a negative current portion of the AC cycle of the first phase of the polyphase AC power source and open, responsive to the occurrence of the short circuit fault, the first low-side switch during a positive current portion of the AC cycle of the first phase of the polyphase AC power source during the second amount of time.

8. The power conversion system of claim 1 , wherein the first switch is a metal oxide silicon field effect transistor (MOSFET).

9. The power conversion system of claim 1 , wherein the power conversion system is a multi-level power conversion system configured to generate high-voltage wave forms from lower-voltage components.

10. The power conversion system of claim 1 , wherein the power conversion system is a neutral point clamped power conversion system.

11. A method of protecting a power conversion system during a short circuit fault, the method comprising:
closing, via a control unit and in response to the short circuit, a first switch connected to a first phase of a polyphase alternating current (AC) power source during a negative current portion of an AC cycle of the first phase of the polyphase AC power source; and
opening, via the control unit and in response to the short circuit, the first switch during a positive current portion of the AC cycle of the first phase of the polyphase AC power source.

12. The method of claim 11 , further comprising:
closing, via a control unit and in response to the short circuit, a second switch connected to a second phase of the polyphase AC power source during a negative current portion of an AC cycle of the second phase of the polyphase AC power source; and
opening, via the control unit and in response to the short circuit, the second switch during a positive current portion of the AC cycle of the second phase of the polyphase AC power source;
closing, via a control unit and in response to the short circuit, a third switch connected to a third phase of the polyphase AC power source during a negative current portion of an AC cycle of the third phase of the polyphase AC power source; and
opening, via the control unit and in response to the short circuit, the third switch during a positive current portion of the AC cycle of the third phase of the polyphase AC power source.

13. The method of claim 12 , wherein each of the first, second, and third phases of the polyphase AC power source output AC that is 120 degrees out of phase with each of the other phases.

14. The method of claim 13 , wherein each of the first, second, and third switches and each of the first, second, and third diodes are configured to be high-side connected between the polyphase AC power source and the electrical load.

15. The method of claim 11 , further comprising:
closing, via a control unit and in response to the short circuit, the first switch f

Assignees

• Rolls Royce Corp
• Rolls Royce Singapore Pte Ltd

Inventors

• Wang Shaui
• Gajanayake Chandana Jayampathi
• Mukherjee Suvajit
• Dasgupta Souvik
• Trawick David Russell

Classifications

• H02M7/2173 Primary

  in a biphase or polyphase circuit arrangement (H02M7/2176 takes precedence; voltage multipliers H02M7/25) · CPC title

• H02M7/219

  in a bridge configuration · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02M7/79

  using devices of a triode or transistor type requiring continuous application of a control signal · CPC title

• H02H7/1257

  responsive to short circuit or wrong polarity in output circuit · CPC title