Testing Inverter Driven Electric Motor Shut-Off Path

• US 20080150573A1
• Filed: 12/22/2006
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: FCA US LLC (Stellantis NV)
• Original Assignee: Chrysler Group LLC (Stellantis NV)
• Inventors: Heller, Marcus, Fu, Zhenxing
• Granted Patent: US 7,545,111 B2
• Time in Patent Office: Days
• US Class Current: 324/772
• CPC Class Codes: G01R 31/24 Testing of discharge tubes during manufacture H01J9/42

Abstract

A method for testing electric motor shut-off including injecting current into an electric motor, applying at least one of a short or an open to the electric motor for a predetermined length of time, calculating the rate of decay of the current and comparing rate of the decay with a predetermined decay criteria. In one implementation, a predefined sequence of opening and short circuiting the electric motor is used, and the shut-off path tests for the motor three phases can be verified with one test.

Claims

1. A method of testing electric traction motor shut-off paths, the method comprising the steps of:

injecting current into a three-phase electric motor;

applying at least one of a short or an open to the three-phase electric motor for a predetermined length of time;

calculating a rate of decay of the current; and

comparing the rate of decay with predetermined decay criteria.

2. The method of claim 1 further comprising checking whether a main contactor is closed before the current is injected.

3. The method of claim 1 further comprising verifying that motor speed is substantially zero before carrying out the applying step.

4. The method of claim 1 further comprising injecting current into the electric motor using a three-phase inverter.

5. The method of claim 1 further comprising measuring current in at least one phase of the three-phase motor.

6. The method of claim 1 wherein the injected current is a substantially zero-amp current in accord with a first axis.

7. The method of claim 1 wherein the injected current is substantially non-zero amp current in accord with a second axis.

8. The method of claim 1 further comprising determining that the injected current is substantially the same as the measured current after the injecting step.

9. The method of claim 1 further comprising determining that testing passed if the rate of decay meets the predetermined decay criteria.

10. A method of diagnosing faults in an electric motor deactivation device, the method comprising the steps of:

injecting current into a three-phase electric motor using a three-phase inverter;

disabling the inverter for a predetermined length of time;

calculating a rate of current decay; and

comparing the rate of current decay with predetermined decay criteria.

11. The method of claim 10 further comprising checking whether the main contactor is closed before the current is injected.

12. The method of claim 10 further comprising verifying that motor speed is substantially zero before carrying out the applying step.

13. The method of claim 10 further comprising injecting current into the electric motor using a three-phase inverter.

14. The method of claim 10 wherein the injected current is a substantially zero-amp current in accord with a first axis L_d.

15. The method of claim 10 wherein the injected current is a substantially non-zero amp current in accord with a second axis L_q.

16. The method of claim 10 further comprising measuring current in at least one phase of the three-phase motor.

17. The method of claim 10 further comprising determining that the test passed if the current decay is within the predetermined ranges.

18. A method for checking an electric motor deactivation device, comprising the steps of:

checking whether a main contactor is closed before current is injected;

injecting current into an electric motor where the current is insufficient to cause motor rotation and includes a non-zero amp direct-axis current and a substantially zero amp quadrature axis current;

measuring current in at least one phase of the three phase motor;

verifying that electric motor speed is substantially zero;

applying a three-phase short to the three-phase electric motor for a predetermined length of time;

calculating a first current decay as a result of the application of the three-phase short;

comparing the first current decay with a current decay criteria;

applying a three-phase open to the electric motor for another predetermined length of time;

calculating a second current decay as a result of the application of the three-phase open; and

comparing the second current decay with another current decay criteria.

19. The method of claim 18 including injecting current into the electric motor using a three-phase inverter.

20. The method of claim 18 including injecting DC current into the electric motor.