Method and apparatus for torque control of a machine

• US 6,566,829 B1
• Filed: 09/07/2000
• Issued: 05/20/2003
• Est. Priority Date: 09/07/2000
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust), Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Nehl, Thomas Wolfgang, Naidu, Malakondaiah, Henry, Rassem Ragheb
• Primary Examiner(s): Nappi, Robert E.
• Assistant Examiner(s): Duda, Rina I.
• Application Number:
  US09/656,903
• Time in Patent Office: 985 Days
• Field of Search: 318/717, 318/718, 318/721, 318/801-811, 318/459, 318/432, 180/421, 180/422, 180/443, 180/446, 701/41, 701/42
• US Class Current: 318/432
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence

Abstract

An exemplary embodiment of the invention is a method for torque control of a PM synchronous machine. The method includes obtaining a torque command signal and a machine speed and determining an operating mode in response to the torque command signal and the machine speed. The operating mode includes a first operating mode and a second operating mode. In the first operating mode, a stator phase voltage magnitude is computed and an angle between the stator phase voltage and a stator phase back emf is determined in response to the stator phase voltage magnitude. In the second operating mode, the stator phase voltage is set to a predetermined magnitude and the angle between the stator phase voltage and the stator phase back emf is determined in response to the predetermined magnitude.

Claims

1. A method for torque control of a machine comprising:

obtaining a torque command signal;

obtaining a machine speed;

determining an operating mode in response to the torque command signal and the machine speed, said operating mode including a first operating mode and a second operating mode;

in the first operating mode, computing a stator phase voltage magnitude and determining an angle between the stator phase voltage and a stator phase back emf in response to the stator phase voltage magnitude;

in the second operating mode, setting the stator phase voltage to a predetermined magnitude and determining the angle between the stator phase voltage and the stator phase back emf in response to the predetermined magnitude.

2. The method of claim 1 wherein:

the stator phase voltage magnitude is computed in response to the torque command signal and the machine speed, and

the angle between the stator phase voltage and the stator phase back emf is determined in response to the torque command signal, the machine speed and the stator phase voltage magnitude.

3. The method of claim 1 wherein:

the predetermined magnitude is based on a battery voltage; and

,

the angle between the stator phase voltage and the stator phase back emf is determined in response to the torque command signal, the machine speed and the predetermined magnitude.

4. The method of claim 3, wherein

in the second mode, the angle 6 between the stator phase voltage and the stator phase back emf is determined by iteratively varying the angle 6 until a computed torque value equals or exceeds a demanded torque value.

5. The method of claim 4 wherein the demanded torque value is

6. The method of claim 1, wherein said machine is part of a vehicular electric power steering system.

7. The method of claim 1 wherein said machine is a permanent magnet motor.

8. A system for control of torque of a machine, the system comprising:

a driver coupled to the machine;

an encoder coupled to a shaft of the machine, the encoder generating a rotation angle signal;

a controller coupled to an input of the driver and coupled to an output of the encoder, wherein the controller;

obtains a torque command signal;

determines a machine speed in response to the rotation angle signal;

determines an operating mode in response to the torque command signal and the machine speed, said operating mode including a first operating mode and a second operating mode;

in the first operating mode, computing a stator phase voltage magnitude and determining an angle between the stator phase voltage and a stator phase back emf in response to the stator phase voltage magnitude;

in the second operating mode, setting the stator phase voltage to a predetermined magnitude and determining the angle between the stator phase voltage and the stator phase back emf in response to the predetermined magnitude.

9. The system of claim 8 wherein:

the stator phase voltage magnitude is computed in response to the torque command signal and the machine speed, and

the angle between the stator phase voltage and the stator phase back emf is determined in response to the torque command signal, the machine speed and the stator phase voltage magnitude.

10. The system of claim 8 wherein:

the predetermined magnitude is based on a battery voltage; and

,

the angle between the stator phase voltage and the stator phase back emf is determined in response to the torque command signal, the machine speed and the predetermined magnitude.

11. The system of claim 10, wherein

in the second mode, the angle δ

between the stator phase voltage and the stator phase back emf is determined by iteratively varying the angle δ

until a computed torque value equals or exceeds a demanded torque value.

12. The system of claim 11 wherein the demanded torque value is

13. The system of claim 8, wherein said machine is part of a vehicular electric power steering system.

14. The system of claim 13 wherein said machine is a motor.

15. The system of claim 8 wherein said driver is a PWM inverter.

16. The system of claim 8 wherein said machine is a permanent magnet motor.