Method of controlling rotary magnet multi-phase synchronous motor and control therefor

• US 5,796,228 A
• Filed: 03/25/1997
• Issued: 08/18/1998
• Est. Priority Date: 09/04/1996
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kojima, Sadaaki, Kato, Satoru, Araki, Hiroshi
• Primary Examiner(s): SIRCUS, BRIAN
• Application Number:
  US08/823,579
• Time in Patent Office: 511 Days
• Field of Search: 318/568.19, 318/568.22, 318/600-605, 318/640, 318/652-670, 318/700, 364/571.01-571.08, 324/207.11-207.26, 340/870.3-870.38
• US Class Current: 318/605
• CPC Class Codes: H02P 25/03 with brushless excitation

Abstract

A method of controlling a rotary magnet multi-phase synchronous motor and a control system based on this method increases the permissible range of accuracy in installing a position detector on the synchronous motor and automatically calculates a phase correction to improve controllability. Using a position detector for detecting a magnet position of a rotary magnet multi-phase synchronous motor and a drive unit, the synchronous motor having the position detector is driven by a drive unit. After the synchronous motor reaches a constant speed, current and drive voltage of the synchronous motor are measured to calculate a phase correction value between a biaxial coordinate axis based upon the installation error of the position detector and a biaxial coordinate system from conversion of a polyphase AC coordinate system based on the measured current and drive voltage, constants of the synchronous motor, and the constant speed. The rotor position of the synchronous motor is corrected based on this phase correction value.

Claims

1. A method of controlling a rotary magnet multi-phase synchronous motor using a position detector for detecting a magnet position of the synchronous motor, and a drive unit for driving the synchronous motor, the control method comprising:

driving a synchronous motor including a position detector using a drive unit to detect when said synchronous motor reaches a constant speed;

measuring a current and a drive voltage of said synchronous motor when said synchronous motor reaches a constant speed;

calculating a phase correction value between a biaxial coordinate axis used for control based on installation error of said position detector and a biaxial coordinate system due to conversion of a polyphase AC coordinate system based on measured current, measured drive voltage, a constant of said synchronous motor, and the constant speed; and

correcting rotor position of said synchronous motor based on the phase correction value.

2. The method as defined in claim 1, wherein the current and drive voltage are components of a current and a drive voltage viewed from the polyphase AC coordinate system.

3. The method as defined in claim 1, wherein the current and drive voltage are components of a current and a drive voltage viewed from the biaxial coordinate axis.

4. The method as defined in claim 1, including calculating the phase correction value between the biaxial coordinate axis based on the installation error of said position detector and the biaxial coordinate system due to conversion of the polyphase AC coordinate system when said position detector is initially attached to said synchronous motor, and thereafter correcting the rotor position of said synchronous motor based on a stored phase correction value.

5. The method as defined in claim 3, including calculating the phase correction value by subtracting a voltage drop due to an armature winding self inductance and a q-axis current component from a d-axis voltage component of the biaxial coordinate axis to produce a first difference, subtracting a voltage drop due to an armature winding resistance and the q-axis current component from a q-axis voltage component to produce a second difference, and dividing the first difference by the second difference.

6. The method as defined in claim 1, wherein the phase correction value is an average of a phase correction value obtained through a forward rotation of said synchronous motor and a phase correction value obtained through reverse rotation of said synchronous motor.

7. The method as defined in claim 1, including using said synchronous motor to drive an elevator winding machine, and calculating the phase correction value where an elevator car and a counterweight of the elevator car are balanced.

8. The method as defined in claim 1, including using said synchronous motor to drive an elevator winding machine, and calculating the phase correction value as an average of a phase correction value obtained when the elevator winding machine is driven in a lifting direction and a phase correction attained when the elevator winding machine is driven in lowering direction.

9. A control system for a rotary magnet multi-phase synchronous motor comprising:

a position detector for detecting a magnet position of a synchronous motor;

a drive unit for driving the synchronous motor;

detection timing detecting means for detecting when the synchronous motor reaches a constant speed;

data pick-up means for measuring a current and a drive voltage of the synchronous motor when the synchronous motor reaches the constant speed;

phase correction value detecting means for calculating a difference in phase between a biaxial coordinate axis based upon installation error of said position detector and a biaxial coordinate system resulting from conversion of a polyphase AC coordinate system based on the measured current, the measured drive voltage, a constant of the synchronous motor, and the constant speed; and

rotor position correction means for correcting rotor position of the synchronous motor based on a phase correction value detected by said phase correction value detecting means.

10. The control system as defined in claim 9, wherein the current and the drive voltage of the synchronous motor are components of a current and a drive voltage viewed from the polyphase AC coordinate system.

11. The control system as defined in claim 9, wherein the current and the drive voltage of the synchronous motor are components of a current and a drive voltage viewed from the biaxial coordinate axis.

12. The control system as defined in claim 9, wherein the phase correction value between the biaxial coordinate axis based on the installation error of said position detector and the biaxial coordinate system due to the conversion of the polyphase AC coordinate system is calculated when said position detector is initially attached to the synchronous motor, and thereafter the rotor position of the synchronous motor is corrected based on a stored phase correction value.

13. The control system as defined in claim 11, wherein the phase correction value is calculated by:

subtracting a voltage drop due to an armature winding self inductance and a q-axis current component of a d-axis voltage component of the biaxial coordinate axis to produce a first difference;

subtracting a voltage drop due to armature winding resistance and the q-axis current component from a q-axis voltage component to produce a second difference; and

dividing the first difference by the second difference.

14. The control system as defined in claim 9, wherein the phase correction value is an average of a phase correction value obtained when the synchronous motor is driven in a forward direction and a phase correction value obtained when the synchronous motor is driven in a reverse direction.

15. The control system as defined in claim 9, wherein the synchronous motor is an elevator winding machine, and the phase correction value is calculated when an elevator car and a counterweight of the elevator, driven by the elevator winding machine, are balanced.

16. The control system as defined in claim 9, wherein the synchronous motor is an elevator winding machine, and the phase correction value is an average value of a phase correction value obtained when the elevator winding machine is driven in a lifting direction and a phase correction value obtained when the elevator winding machine is driven in a lowering direction.