Inverter diagnostic testing methods and apparatus

Patent metadata

Field	Value
Publication number	US-12360174-B2
Application number	US-202218064413-A
Country	US
Kind code	B2
Filing date	Dec 12, 2022
Priority date	Dec 12, 2022
Publication date	Jul 15, 2025
Grant date	Jul 15, 2025

Abstract

Methods of testing a multilevel inverter include selectively pulsing (i.e., attempting to turn on) at least one of the inner and outer switches of the inverter and determining a status of at least one of the inner switches, the outer switches and the neutral clamping diodes of the inverter based whether the pulsed at least one of the inner and outer switches desaturates. The pulsing may be preceded by charging the DC bus to a predetermined voltage magnitude that is less than a nominal working voltage magnitude of the DC bus, e.g., the predetermined voltage magnitude may be around 50% or less of the nominal working voltage magnitude.

First claim

What is claimed is:

1. A method of testing a multilevel inverter comprising a plurality of poles coupled to a DC bus, each pole having inner and outer switches and a neutral clamping diode coupled thereto, the method comprising:
charging the DC bus to a predetermined voltage magnitude that is less than a nominal working voltage magnitude of the DC bus;
selectively pulsing at least one of the inner and outer switches; and
determining a status of at least one of the inner switches, the outer switch and the neutral clamping diodes based whether the pulsed at least one of the inner and outer switches desaturates.

2. The method of claim 1 , wherein the predetermined voltage magnitude is around 50% or less of the nominal working voltage magnitude.

3. The method of claim 1 :
wherein the charging of the DC bus comprises:
connecting the DC bus to a DC power source to charge the DC bus; and
disconnecting the DC bus from the DC power source responsive to a magnitude of a voltage of the DC bus meeting or exceeding the predetermined voltage magnitude; and

wherein the pulsing occurs after disconnecting the DC bus from the DC power source.

4. The method of claim 1 , wherein the pulsing is for a duration sufficient to allow desaturation of the pulsed switch without exceeding ratings of the switches and diodes of the inverter.

5. The method of claim 1 , further comprising:
selectively pulsing at least one of the inner and outer switches; and
responsively determining a status of at least one of the inner switches and the outer switches based whether a non-zero phase current for a load attached to the inverter occurs.

6. A method of testing a multilevel inverter comprising a plurality of poles coupled to a DC bus, each pole having inner and outer switches and a neutral clamping diode coupled thereto, the method comprising:
by charging the DC bus to a predetermined voltage magnitude that is less than a nominal working voltage magnitude of the DC bus;
selectively pulsing at least one the inner and outer switches; and
determining a status of at least one of the inner switches and the outer switches based whether a non-zero phase current for a load attached to the inverter occurs in response to the pulsing.

7. The method of claim 6 , wherein the predetermined voltage magnitude is around 50% or less of the nominal working voltage magnitude.

8. The method of claim 6 :
wherein the charging of the DC bus comprises:
connecting the DC bus to a DC power source to charge the DC bus; and
disconnecting the DC bus from the DC power source responsive to a magnitude of a voltage of the DC bus meeting or exceeding the predetermined voltage magnitude; and

wherein the pulsing occurs after disconnecting the DC bus from the DC power source.

9. A method of testing a multilevel inverter comprising a positive pole and a negative pole coupled to a DC bus, each of the positive and negative poles comprising an outer switch, an inner switch and a neutral clamping diode, the method comprising:
charging the DC bus to a predetermined voltage magnitude that is less than a nominal working voltage magnitude of the DC bus;
pulsing one of the outer switches; and
determining a status of at least one of the inner switches and the neutral clamping diodes based on whether the one of the outer switches desaturates in response to the pulsing.

10. The method of claim 9 , further comprising:
pulsing the inner switches of the positive and negative poles; and
determining a status of at least one of the positive pole inner switch, the negative pole outer switch and the positive pole outer switch based on whether either of the pulsed inner switches desaturates.

11. The method of claim 9 , further comprising:
pulsing the inner and outer switches of a first one of the positive and negative poles; and
determining a status of at least one of the inner switch and the neutral clamping diode of a second one of the positive and negative poles based on whether either of the pulsed inner and outer switches desaturates.

12. The method of claim 11 , further comprising:
pulsing one of a combination of the positive pole inner switch for a first phase and the negative pole inner switch for a second phase or the negative pole inner switch for the second phase; and
determining a status of the positive pole inner switch for the first phase based on whether the pulsing of the one of the combination of the positive pole inner switch for a first phase and the negative pole inner switch for a second phase or the negative pole inner switch for the second phase produces a current in the first phase.

13. The method of claim 12 , wherein the inverter comprises at least two phases, each comprising positive and negative poles, the method further comprising:
pulsing one of the negative pole inner switch of the second phase or a combination of a positive pole inner switch of a first phase and a negative pole inner switch of a second phase; and
determining a status of a positive pole outer switch of the first phase based on whether the pulsing of the one of the negative pole inner switch of the second phase or a combination of a positive pole inner switch of a first phase and a negative pole inner switch of a second phase produces a current in the first phase.

14. The method of claim 13 , further comprising:
pulsing one of the negative pole inner switch of the second phase, a combination of the positive pole outer switch of the first phase and the negative pole inner switch of the second phase or a combination of the negative pole inner switch and the negative pole outer switch of the second phase or a third phase; and
determining a status of the positive pole inner switch of the second phase based on whether the pulsing of the one of the negative pole inner switch of the second phase, a combination of the positive pole outer switch of the first phase and the negative pole inner switch of the second phase or a combination of the negative pole inner switch and the negative pole outer switch of the first phase or a third phase produces a current in the first phase.

15. The method of claim 14 , further comprising:
pulsing one of a combination of the positive pole outer switch of the first phase, the positive pole inner switch of the first phase and the negative pole inner switch of the second phase or a combination of the positive pole inner switch of the first phase and the negative pole inner and outer switches of the second phase or the third phase; and
determining the status of the positive pole inner switch of the first phase based on whether the pulsing of the one of a combination of the positive pole outer switch of the first phase, the positive pole inner switch of the first phase and the negative pole inner switch of the second phase or a combination of the positive pole inner switch of the first phase and the negative pole inner and outer switches of the second phase or the third phase produces a non-zero current in the first phase.

16. The method of claim 14 , further comprising:
pulsing a combination of the positive pole outer switch for the first phase, the positive pole inner switch for the first phase and the negative pole inner switch for the second phase;
determining a status of the positive pole outer switch of the first phase based on whether the pulsing of the combination of the positive pole outer switch for the first phase, the positive pole inner switch for the first phase and the negative pole inner switch for the second phase produces a current in the first phase; and
if the pulsing of the combination of the positive pole o

Assignees

• Eaton Intelligent Power Ltd

Inventors

• Simms Stan Rex
• Gibbs Irving A
• Braga Gabriel
• Farr Thomas A

Classifications

• H02M7/487

  Neutral point clamped inverters · CPC title

• G01R31/42 Primary

  AC power supplies · CPC title