On-line diagnostic method for electronic switch faults in neutral-point-clamped converters

Patent metadata

Field	Value
Publication number	US-11119159-B2
Application number	US-201615775247-A
Country	US
Kind code	B2
Filing date	Nov 10, 2016
Priority date	Nov 13, 2015
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

Systems and methods of diagnosing open-circuit fault in power converters receives a neutral point current value, a switching state of the power converter, and load current values. At least one fault condition is identified based upon the switching state of the power converter and the load current values. The neutral point current value current value is compared to the at least one fault condition. An open circuit fault is determined to be present at the switching state of the power converter based upon the comparison.

First claim

The invention claimed is:

1. A method of diagnosing an open-circuit fault in a power converter, the method comprising:
receiving a neutral point current value;
receiving a switching state of the power converter;
receiving load current values;
identifying at least one fault condition based upon the switching state of the power converter and the load current values;
comparing the neutral point current value to the at least one fault condition;
determining an open-circuit fault is present at the switching state based upon the comparison; and
initiating a response based upon the determination of the open-circuit fault.

2. The method of claim 1 , wherein the power converter is a neutral-point clamped (NPC) power converter.

3. The method of claim 2 , wherein the NPC power converter is a three-phase power converter and the load current values comprise an A phase leg load current value, a B phase leg load current value, and a C phase leg load current value.

4. The method of claim 1 , wherein the switch devices comprise at least one of Insulated Gate Bipolar Transistors (IGBT) and Metal Oxide Field Effect Transistors (MOSFET).

5. The method of claim 1 , wherein determining the at least one fault condition further comprises:
calculating an expected neutral point current value based upon the switching state of the power converter and the load current values;
comparing the received neutral point current value to the expected neutral point current value; and
determining a probable fault condition based upon the comparison.

6. The method of claim 5 , wherein determining the at least one fault condition further comprises:
identifying at least one fault condition based upon the switching state of the power converter; and
comparing the received neutral point current value to the at least one fault condition;
wherein the open-circuit fault is determined to be present based upon the comparison.

7. The method of claim 1 , wherein determining the at least one fault condition further comprises:
identifying at least one confirmation condition based upon the switching state of the power converter and at least one fault condition compared to the neutral point current value; and
comparing the neutral point current value to the at least one confirmation condition;
wherein determining the open-circuit fault to be present further comprises identifying a location of the open-circuit fault based upon the comparison of the neutral point current value to the at least one fault condition and at least one confirmation condition.

8. The method of claim 1 , wherein determining the at least one fault condition further comprises:
identifying at least one fault condition based upon the switching state of the power converter; and
comparing the received neutral point current value to the at least one fault condition;
wherein the open-circuit fault is determined to be present based upon the comparison.

9. The method of claim 8 , wherein the at least one fault condition is a value selected from zero, and the load current values.

10. The method of claim 8 , wherein determining the at least one fault condition further comprises:
identifying at least one confirmation condition based upon the switching state of the power converter and at least one fault condition compared to the neutral point current; and
upon determining that the neutral point current value meets at least one fault condition, comparing the received neutral point current value to the at least one confirmation condition;
wherein determining the open-circuit fault to be present further comprises identifying a location of the open-circuit fault based upon the comparison of the neutral point current value to the at least one fault condition and at least one confirmation condition.

11. The method of claim 10 , wherein identifying the at least one fault condition and identifying the at least one confirmation condition comprises referencing a look-up table with the switching state of the power converter to point to the at least one fault condition and at least one confirmation condition.

12. The method of claim 1 , wherein the power converter comprises at least one auxiliary switch and the response comprises operating at least one auxiliary switch to remediate the detected open-switch fault.

13. The method of claim 1 , wherein the response comprises operating a graphical display to present a report of the detected open-switch fault and a location of the open-switch fault.

14. A system for diagnosing open-circuit faults in a multi-level power converter, the system comprising:
a neutral point current transducer configured to measure a neutral point current value from a DC-bus midpoint of the power converter;
load current transducers configured to measure load current values from a plurality of phase legs of the multi-level power converter; and
a microcontroller that receives a switching state of the multi-level power converter, receives the neutral point current value from the neutral point current transducer, and receives the load current values from the load current transducers, the microcontroller further identifies least one fault condition based upon the switching state and the load current values, compares the neutral point current value to the at least one fault condition, determines an open-circuit fault is present at the switching state based upon the comparison, and initiates a response based upon the determination of the open-circuit fault.

15. The system of claim 14 , wherein the microcontroller is configured to operate the multi-level power converter through a plurality of switching states, and the microcontroller provides the switching state to itself.

16. The system of claim 14 , further comprising a current transducer that measures a value of the neutral point current and provides the value to the microcontroller.

17. The system of claim 14 , wherein the microcontroller calculates an expected neutral point current value based upon the switching state of the power converter and the load current values, compares the received neutral point current value to the expected neutral point current value, and determines a probable fault condition based upon the comparison.

18. The system of claim 17 , wherein if the microcontroller determines a probable fault condition, the microcontroller identifies at least one fault condition and at least one confirmation condition based upon the switching state of the power converter, compares the received neutral point current value to the at least one fault condition, and based upon the comparison to the at least one fault condition, compares the received neutral point current value to the at least one confirmation condition and determines the open-circuit fault to be present and identifies a location of the open-circuit fault based upon the comparisons.

19. The system of claim 14 , further comprising:
wherein the microcontroller references a look-up table with the switching state of the power converter to point to the at least one fault condition and at least one confirmation condition to identify the at least one fault condition and at least one confirmation; and
wherein the microcontroller compares the received neutral point current value to the at least one fault condition, and based upon the comparison to the at least one fault condition, compares the received neutral point current value to the at least one confirmation condition and determines the open-circuit fault to be present and identifies a location of the open-circuit fault based upon the

Assignees

• Univ Marquette

Inventors

• He Jiangbiao
• Demerdash Nabeel A O

Classifications

• H02M7/537

  using semiconductor devices only, e.g. single switched pulse inverters · CPC title

• H02M7/487

  Neutral point clamped inverters · CPC title

• H02M7/00

  Conversion of AC power input into DC power output; Conversion of DC power input into AC power output · CPC title

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title

• H02H7/1227

  responsive to abnormalities in the output circuit, e.g. short circuit · CPC title