AGING DETERMINATION OF POWER SEMICONDUCTOR DEVICE IN ELECTRIC DRIVE SYSTEM

• US 20160377671A1
• Filed: 06/24/2016
• Published: 12/29/2016
• Est. Priority Date: 06/25/2015
• Status: Active Application

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: Abb Oy (ABB Limited)
• Inventors: Sjoroos, Jukka-Pekka, Tikkanen, Kari
• Granted Patent: US 10,261,122 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 31/005 Testing of electric installations on transport means
• CPC Class Codes: G01R 31/2608 for testing bipolar transistors
• CPC Class Codes: G01R 31/2642 Testing semiconductor operation lifetime or reliability, e.g. by accelerated life tests
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36

Abstract

Monitoring aging in an electric drive system includes energizing the electric drive system such that electrical current flows through a power semiconductor device therein, determining a value indicative of a voltage across the power semiconductor device, at a current level where voltage is substantially independent of temperature, comparing the determined value with a reference value, and outputting a signal responsive to a difference between the values that is indicative of an aging state of the power semiconductor device.

Claims

1. A method of monitoring aging in an electric drive system comprising:

energizing the electric drive system such that electrical current flows through a power semiconductor device in the electric drive system;

determining a value indicative of a voltage across the power semiconductor device, at a level of the electrical current where the voltage is substantially independent of a temperature of the power semiconductor device;

comparing the determined value with a reference value; and

outputting a signal indicative of an aging state of the power semiconductor device responsive to a difference between the determined value and the reference value.

2. The method of claim 1 further comprising powering an external load via the electric drive system, during the energizing of the electric drive system.

3. The method of claim 1 wherein the determined value includes an average value of the voltage in a plurality of sampling periods after placing the power semiconductor device in service in the electric drive system, and wherein the reference value includes a stored reference value indicative of a starting voltage across the power semiconductor device prior to service in the electric drive system.

4. The method of claim 1 wherein outputting a signal includes outputting a warning signal to a user interface of the electric drive system where the difference is indicative of an aging state of about 90% or greater.

5. The method of claim 4 wherein outputting a signal includes outputting the warning signal where the difference is indicative of an increase in voltage drop across the power semiconductor of about 2% or greater.

6. The method of claim 1 further comprising calculating a remaining life of the power semiconductor device responsive to the signal at least in part by multiplying logged service hours of the power semiconductor device by a proportional multiplier.

7. The method of claim 1 wherein the power semiconductor device includes a transistor, and determining the value includes determining a voltage drop via sensing leads electrically connected to a collector and an emitter of the transistor.

8. The method of claim 1 wherein the power semiconductor device includes a diode, and determining the value includes determining a voltage drop via sensing leads electrically connected to an anode and a cathode of the diode.

9. A method of determining health of power semiconductor devices in an electric drive system comprising:

energizing the electric drive system such that electrical current flows through a power semiconductor device therein at a first level where a relation between electrical current level and voltage across the power semiconductor device is dependent on temperature;

energizing the electric drive system such that electrical current flows through the power semiconductor device at a second level where the relation is substantially independent of temperature;

sensing voltage across the power semiconductor device where the electrical current is at the second level; and

setting a fault responsive to the sensed voltage.

10. The method of claim 9 wherein the power semiconductor device includes an insulated gate bipolar transistor (IGBT), and the first level is from about 50 Amps to about 75 Amps.

11. The method of claim 9 wherein the power semiconductor device includes a freewheeling diode, and the first level is from about 75 Amps to about 100 Amps.

12. The method of claim 9 wherein sensing the voltage includes sensing the voltage in a plurality of sampling periods so as to determine an average voltage, and further comprising comparing the average voltage with a reference voltage.

13. The method of claim 12 wherein the power semiconductor device is in an on-state and the electric drive system supplies electrical power to an external electrical load during the energizing of the electric drive system.

14. An electric drive system comprising:

a power module for conveying electrical power between an electrical power supply and an external electrical load;

a power semiconductor device within the power module;

a sensing mechanism having sensing leads coupled to electrical terminals of the power semiconductor device, and a controller coupled to the sensing leads;

the controller being structured to determine a value indicative of a voltage across the power semiconductor device when electrical current through the power semiconductor device is at a level where the voltage is substantially independent of a temperature of the power semiconductor device; and

the controller being further structured to compare the determined value with a reference value, and to output a signal indicative of an aging state of the power semiconductor device responsive to a difference between the determined value and the reference value.

15. The electric drive system of claim 14 further comprising a user interface coupled with the sensing mechanism, and wherein the signal includes a warning signal and the controller is further structured to output the warning signal to the user interface where the difference is indicative of an expected increase in a rate of change of the voltage over a plurality of power cycles.

16. The electric drive system of claim 15 wherein the power semiconductor device includes a transistor, and the sensing leads of the sensing mechanism are coupled to a collector and an emitter of the transistor.

17. The electric drive system of claim 16 wherein the transistor includes an insulated gate bipolar transistor (IGBT).

18. The electric drive system of claim 16 further comprising a freewheeling diode connected electrically in parallel with the transistor.

19. The electric drive system of claim 18 wherein the sensing mechanism further includes a comparator coupled with each of the freewheeling diode and the transistor via the sensing leads.

20. The electric drive system of claim 14 further comprising a plurality of input nodes for coupling the electric drive system with a plurality of phases of an AC power supply, and a plurality of output nodes for coupling the electric drive system with an external load, and the power semiconductor device including one of a plurality of power semiconductor devices coupled between the input nodes and the output nodes.

21. The electric drive system of claim 20 wherein the sensing mechanism is structured to sense the voltage across the power semiconductor device when the power semiconductor device is energized and the electric drive system supplies electrical power from the AC power supply to the external load.