Demagnetization for a motor in an electric or partially electric motor vehicle

• US 20030055584A1
• Filed: 09/17/2001
• Published: 03/20/2003
• Est. Priority Date: 09/17/2001
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Curran, Patrick J., Raftari, Abbas, Garg, Vijay K.
• Granted Patent: US 6,720,792 B2
• Time in Patent Office: Days
• US Class Current: 702/58
• CPC Class Codes: B60K 6/26 characterised by the motors or the generators
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/427 Voltage
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2250/10 by alarm
• CPC Class Codes: B60L 2270/145 Structure borne vibrations
• CPC Class Codes: B60L 3/0061 relating to electrical machines
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02K 11/20 for measuring, monitoring, testing, protecting or switching rectifiers H02K11/04; power electronics H02K11/33
• CPC Class Codes: H02K 11/35 Devices for recording or transmitting machine parameters, e.g. memory chips or radio transmitters for diagnosis
• CPC Class Codes: H02K 15/03 : having permanent magnets
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y10S 903/906 : Motor or generator

Abstract

In an electric or hybrid electric vehicle, a voltage monitor (102) is directly coupled to a traction motor (38) and/or generator motor (30) to detect a permanent magnet induced voltage within the motor at a predetermined speed and no load condition. A controller (100) compares the detected permanent magnet induced voltage with an expected reference voltage that represents an expected permanent magnet induced voltage at full magnetization and the predetermined speed. The comparison includes identifying points of synchronization and using those points to determine a difference in the detected permanent magnet induced voltage that is caused by a faulty component.

Claims

1. A device for detecting faults due to permanent magnet degradation in a motor in a vehicle comprising:

a permanent magnet induced voltage monitor that measures a detected permanent magnet induced voltage of the motor at a predetermined speed; and

a processor that;

compares the detected permanent magnet induced voltage with a reference voltage that reflects a permanent magnet induced voltage of the motor with a fully magnetized permanent magnet at the predetermined speed; and

analyzes the detected permanent magnet induced voltage with reference to the reference voltage to determine whether a characteristic of the detected permanent magnet induced voltage indicates a component of the motor is faulty.

2. The device of claim 1 wherein the permanent magnet induced voltage monitor comprises coils on a stator of the motor and a voltmeter coupled to the coils to detect the detected permanent magnet induced voltage.

3. The device of claim 1 wherein the processor analyzes the detected permanent magnet induced voltage with reference to a point of synchronization that relates to a position of a permanent magnet in the motor.

4. The device of claim 3 wherein the point of synchronization is caused by a predetermined irregularity in the motor.

5. The device of claim 4 wherein the predetermined irregularity is formed in one of a rotor and a permanent magnet.

6. The device of claim 3 wherein the point of synchronization is caused by a predetermined change in one of motor reluctance and magnetic strength.

7. A method for identifying a component that is faulty and causing permanent magnet degradation in a motor of a vehicle, the method comprising the steps of:

detecting a first signal that is a function of permanent magnetization of a plurality of permanent magnets in the motor;

comparing the first signal with a reference signal that represents a function of permanent magnetization of the plurality of magnets in the motor, wherein the reference signal reflects a level of magnetization that is expected where the plurality of permanent magnets in the motor are fully magnetized; and

analyzing a difference between the first signal and the reference signal to determine a faulty component that is likely causing the difference.

8. The method of claim 7 further comprising the step of:

setting a diagnostic code indicating the faulty component.

9. The method of claim 7 wherein the first signal is a permanent magnet induced voltage and the reference signal is a permanent magnet induced voltage.

10. The method of claim 7 wherein the first signal includes a point of synchronization and the reference signal includes a point of synchronization.

11. The method of claim 10 wherein the point of synchronization of the first signal is determined by a predetermined irregularity in the motor.

12. The method of claim 11 wherein the predetermined irregularity causes a change in one of motor reluctance and magnetic strength.

13. The method of claim 9 wherein the first signal is detected by inducing a voltage in a coil adjacent a stator of the motor.

14. A device for identifying a component that is faulty and causing permanent magnet degradation in a motor of a vehicle, the device comprising:

a processor that;

receives a first signal that is a function of permanent magnetization of a plurality of permanent magnets in the motor;

compares the first signal with a reference signal that represents a function of permanent magnetization of the plurality of magnets in the motor, wherein the reference signal reflects a level of magnetization that is expected where the plurality of permanent magnets in the motor are fully magnetized;

analyzes a difference between the first signal and the reference signal to determine a faulty component that is likely causing the difference.

15. The device of claim 14 further comprising the processor setting a diagnostic code indicating the faulty component.

16. The device of claim 14 wherein the first signal is a permanent magnet induced voltage and the reference signal is a permanent magnet induced voltage.

17. The device of claim 14 wherein the first signal includes a point of synchronization and the reference signal includes a point of synchronization.

18. The device of claim 17 wherein the point of synchronization of the first signal is determined by a predetermined irregularity in the motor.

19. The device of claim 18 wherein the predetermined irregularity is formed in one of a rotor and a permanent magnet of the plurality of permanent magnets.

20. The device of claim 16 wherein the first signal is detected by inducing a voltage in a coil adjacent a stator of the motor.