Method and apparatus for controlling an electric machine

Patent metadata

Field	Value
Publication number	US-9242576-B1
Application number	US-201414340642-A
Country	US
Kind code	B1
Filing date	Jul 25, 2014
Priority date	Jul 25, 2014
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

A method for operating an electric machine of a ground vehicle includes periodically determining an aging parameter based upon a temperature of the electric machine and periodically determining a short-term aging effect based upon the periodically determined aging parameter. A long-term aging effect is determined based upon the short-term aging effect. A short-term temperature adjustment is determined based upon the short-term aging effect and a long-term temperature adjustment is determined based upon the long-term aging effect. A temperature-based derated motor torque is determined based upon the long-term temperature adjustment and the short-term temperature adjustment. Operation of the electric machine is controlled responsive to an operator command for torque based upon the temperature-based derated motor torque.

First claim

The invention claimed is:

1. A method for operating a high-voltage electric machine of a ground vehicle, comprising:
periodically determining an aging parameter based upon a temperature of the electric machine;
periodically determining a short-term aging effect based upon the periodically determined aging parameter;
determining a long-term aging effect based upon the short-term aging effect;
determining a short-term temperature adjustment based upon the short-term aging effect;
determining a long-term temperature adjustment based upon the long-term aging effect;
determining a temperature-based derated motor torque based upon the long-term temperature adjustment and the short-term temperature adjustment; and
controlling, by a controller, operation of the electric machine based upon the temperature-based derated motor torque.

2. The method of claim 1 , wherein periodically determining an aging parameter based upon the temperature of the electric machine comprises:
empirically developing a temperature-aging relationship based upon temperature-induced changes in insulative material of insulated conductive wires of the electric machine; and
periodically determining the aging parameter based upon the temperature of the electric machine and the empirically developed temperature-aging relationship.

3. The method of claim 2 , wherein empirically developing a temperature-aging relationship based upon temperature-induced changes in insulative material of insulated conductive wires of the electric machine comprises empirically developing the temperature-aging relationship based upon fatigue of the insulative material induced by cyclically applied loads related to temperature of the electric machine.

4. The method of claim 1 , wherein periodically determining a short-term aging effect based upon the periodically determined aging parameters comprises dynamically integrating the periodically determined aging parameters during each driving cycle.

5. The method of claim 1 , wherein determining a long-term aging effect based upon the short-term aging effect comprises accumulating the periodically determined short-term aging effects and, at the end of a present driving cycle, integrating the accumulated short-term aging effects with a long-term aging effect determined during a previous driving cycle.

6. The method of claim 1 , wherein determining a short-term temperature adjustment based upon the short-term aging effect comprises dynamically determining a short-term adjustment in temperature based upon a temperature-induced material stress in the electric machine.

7. The method of claim 6 , further comprising resetting the short-term temperature adjustment to zero at the beginning of each driving cycle.

8. The method of claim 1 , wherein determining a long-term temperature adjustment based upon the long-term aging effect comprises determining a long-term adjustment in temperature based upon temperature-induced material stress in the electric machine, said long-term temperature adjustment updated once each driving cycle.

9. The method of claim 1 , wherein controlling, by a controller, operation of the electric machine based upon the temperature-based derated motor torque comprises dynamically controlling maximum torque output of the electric machine, said maximum torque output limited by the temperature-based derated motor torque.

10. A method for operating an electrically-powered torque machine configured to generate tractive torque in a ground vehicle, comprising:
periodically determining an aging parameter based upon a temperature of the electric machine;
determining a short-term aging effect based upon an accumulation of the periodically determined aging parameter;
determining a long-term aging effect based upon an accumulation of the short-term aging effect;
determining a short-term temperature adjustment based upon the short-term aging effect;
determining a long-term temperature adjustment based upon the long-term aging effect;
determining a temperature-based derated motor torque based upon the long-term temperature adjustment and the short-term temperature adjustment; and
controlling, by a controller, operation of the electric machine responsive to an operator command for torque limited based upon the temperature-based derated motor torque.

11. The method of claim 10 , wherein periodically determining an aging parameter based upon a temperature of the electric machine comprises:
empirically developing a temperature-aging relationship based upon fatigue of the insulative material induced by cyclically applied loads related to temperature of the electric machine; and
periodically determining the aging parameter based upon the temperature of the electric machine and the empirically developed temperature-aging relationship.

12. The method of claim 10 , wherein determining a short-term aging effect based upon an accumulation of the periodically determined aging parameters comprises dynamically integrating the periodically determined aging parameters during each driving cycle.

13. The method of claim 10 , wherein determining a long-term aging effect based upon an accumulation of the short-term aging effect comprises accumulating the short-term aging effects and, at the end of a present driving cycle, integrating the accumulated short-term aging effects with a long-term aging effect determined during a previous driving cycle.

14. The method of claim 10 , wherein determining a short-term temperature adjustment based upon the short-term aging effect comprises dynamically determining a short-term adjustment in temperature based upon a temperature-induced material stress in the electric machine.

15. The method of claim 14 , further comprising resetting the short-term temperature adjustment to zero at the beginning of each driving cycle.

16. The method of claim 10 , wherein determining a long-term temperature adjustment based upon the long-term aging effect comprises determining a long-term adjustment in temperature based upon temperature-induced material stress in the electric machine, said long-term temperature adjustment updated once each driving cycle.

17. The method of claim 10 , wherein controlling, by a controller, operation of the electric machine responsive to an operator command for torque limited based upon the temperature-based derated motor torque comprises dynamically controlling operation of the electric machine responsive to the operator command for torque limited based upon a maximum torque output of the electric machine, said maximum torque output limited by the temperature-based derated motor torque.

Assignees

• Gm Global Tech Operations Inc

Inventors

• Turnbull Paul F
• Hayslett Steven L
• Bauer Harry J
• Berry Daniel J
• Dolan George D

Classifications

• H02P29/00

  Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors (arrangements for starting electric motors H02P1/00; arrangements for stopping or slowing electric motors H02P3/00; control of motors that can be connected to two or more different electric power supplies H02P4/00; regulating or controlling the speed or torque of two or more electric motors H02P5/00; vector control H02P21/00) · CPC title

• B60L15/20 Primary

  for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed · CPC title

• Y02T10/64

  Electric machine technologies in electromobility · CPC title

• B60L2240/423

  Torque · CPC title

• H02P29/60

  Controlling or determining the temperature of the motor or of the drive (H02P29/02 takes precedence) · CPC title