APPARATUS AND METHOD FOR POWER SWITCH HEALTH MONITORING

• US 20130328596A1
• Filed: 06/11/2012
• Published: 12/12/2013
• Est. Priority Date: 06/11/2012
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Zoels, Thomas Alois, Curbelo, Alvaro Jorge Mari
• Granted Patent: US 8,957,723 B2
• Time in Patent Office: Days
• US Class Current: 327/109
• CPC Class Codes: H03K 17/18 Modifications for indicating state of switch

Abstract

A method includes obtaining a standard value for a characteristic of a power switch and obtaining a measured value of the characteristic, via a gate drive unit connected to a gate terminal of the power switch. The method also includes determining a health state of the power switch by comparing the measured value to the standard value of the characteristic.

Claims

1. A method comprising:

obtaining a standard value for a characteristic of a power switch;

obtaining a measured value of the characteristic, via a gate drive unit connected to a gate terminal of the power switch; and

determining a health state of the power switch based on a comparison of the measured value to the standard value of the characteristic.

2. A method as claimed in claim 1, wherein the measured value is compared to the standard value within the gate drive unit.

3. A method as claimed in claim 2, wherein the gate drive unit periodically transmits a health monitoring signal to a central controller separate from the gate drive unit, and wherein the health monitoring signal includes information of the health state.

4. A method as claimed in claim 1, wherein the measured value is compared to the standard value within a central controller separate from the gate drive unit.

5. A method as claimed in claim 1, wherein the characteristic comprises at least one of

a stray inductance of a commutation path associated with the power switch when the power switch is switched on or off,

an estimated thermal resistance to heat transfer from the power switch junction to the power switch case,

a voltage drop across the power switch while the power switch is conducting,

a gate voltage threshold level when the power switch starts to conduct,

a Miller capacitance of the power switch,

a collector to gate capacitance of the power switch, or

a parameter of a time function describing current through the power switch.

6. A method as claimed in claim 1, wherein the characteristic is a gate to emitter capacitance of the power switch.

7. A method as claimed in claim 6, further comprising reporting a failure location based on repeated comparison, during a sequence of power transients, of the measured value of the characteristic to the standard value of the characteristic.

8. A method as claimed in claim 1, further comprising recommending replacement of a power switch, based on the determined health state of the power switch.

9. A system comprising:

a gate drive unit comprising;

an output stage configured to deliver gate voltage and/or gate current to a power switch; and

a sensor module configured to obtain a measured value of a characteristic of the power switch; and

a controller configured to determine a health state of the power switch based on a comparison of the measured value to a standard value of the characteristic.

10. A gate drive unit as claimed in claim 9, wherein the controller is incorporated into the gate drive unit.

11. A gate drive unit as claimed in claim 9, wherein the controller is separate from the gate drive unit and is configured to communicate with other gate drive units.

12. A gate drive unit as claimed in claim 9, wherein the controller is configured to periodically transmit a health monitoring signal to a different controller, and wherein the health monitoring signal includes information of the health state.

13. A gate drive unit as claimed in claim 9, wherein the characteristic comprises at least one of

a stray inductance of a commutation path associated with the power switch when the power switch is switched on or off,

an estimated thermal resistance to heat transfer from the power switch junction to the power switch case,

a voltage drop across the power switch while the power switch is conducting,

a gate voltage threshold level when the power switch starts to conduct,

a Miller capacitance of the power switch,

a collector to gate capacitance of the power switch,

a parameter of a time function describing current through the power switch, or

a gate to emitter capacitance of the power switch.

14. A power converter comprising:

a plurality of power switches;

a plurality of gate drive units comprising;

output stages connected to deliver gate voltages and/or gate currents to the plurality of power switches; and

sensor modules connected to obtain, during operation of the power converter, measured values of at least one characteristic of the plurality of power switches; and

at least one controller configured to determine health states of the power switches based on comparisons of the plurality of measured values to at least one standard value.

15. A power converter as claimed in claim 14, wherein the at least one controller includes a plurality of controllers respectively incorporated into the gate drive units.

16. A power converter as claimed in claim 14, wherein the characteristic is at least one of

a stray inductance of a commutation path associated with the power switch when the power switch is switched on or off,

an estimated thermal resistance to heat transfer from the power switch junction to the power switch case,

a voltage drop across the power switch while the power switch is conducting,

a gate voltage threshold level when the power switch starts to conduct,

a Miller capacitance of the power switch,

a collector to gate capacitance of the power switch,

a parameter of a time function describing current through the power switch, or

a gate to emitter capacitance of the power switch.

17. A power converter as claimed in claim 14, wherein the at least one controller is configured to report a risk of power switch failure based on a determined health state.

18. A method comprising:

monitoring respective health states of a plurality of power switches in a power converter; and

communicating information of the health states to a recipient remote from the power converter;

wherein the step of monitoring the health states comprises;

obtaining from a memory unit one or more respective standard values for one or more characteristics of the power switches;

periodically obtaining measured values of the one or more characteristics of the power switches during operation of the power converter; and

periodically determining the health states based on comparisons of the measured values to the standard values.

19. The method of claim 18, wherein the information identifies one or more of the plurality of power switches to be repaired or replaced.