Multi-phase motor control method and device using the same

Patent metadata

Field	Value
Publication number	US-9654037-B2
Application number	US-201414461918-A
Country	US
Kind code	B2
Filing date	Aug 18, 2014
Priority date	Sep 11, 2013
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

A multi-phase motor control method controls a multi-phase motor which includes multiple nodes respectively receiving a corresponding number of driving voltage signals to control a rotation of a rotor. The motor control method includes: sensing a signal phase of a current signal corresponding to at least one node, for example by sensing a zero-crossing point of the current signal; determining a reference phase for the current signal; calculating a phase difference between the signal phase and the reference phase; and controlling a phase switching frequency of the stator according to the phase difference, such that the signal phase is close to or in phase with the reference phase, to thereby obtain an optimum rotation speed of the rotor corresponding to a given driving voltage. The present invention also provides a multi-phase motor control device using the motor control method.

First claim

What is claimed is:

1. A multi-phase motor control method for controlling a multi-phase motor which includes a plurality of nodes respectively receiving a corresponding number of driving voltage signals to control a rotation of a rotor in the multi-phase motor, the multi-phase motor control method comprising:
sensing a current signal corresponding to one of the plurality of nodes and detecting a signal phase of the current signal;
comparing the signal phase of the current signal with a reference phase of a desired target current signal which is obtained according to the driving voltage signals, to determine a phase difference; and
adjusting a rotation speed of the rotor by adjusting phase switching frequencies of the driving voltage signals according to the comparing result.

2. The multi-phase motor control method of claim 1 , wherein the driving voltage signals are sinusoidal driving voltage signals, or space vector pulse width modulation signals.

3. The multi-phase motor control method of claim 1 , wherein the step of comparing the signal phase of the current signal with a reference phase of a desired target current signal to determine a phase difference comprises:
detecting a zero-crossing point between the current signal and a ground;
determining a zero-crossing point of the desired target current signal; and
calculating a time difference between the zero-crossing points of the current signal and the desired target current signal to determine the phase difference.

4. The multi-phase motor control method of claim 3 , wherein the zero-crossing point of the desired target current signal is equal to a zero-crossing point between the driving voltage signal corresponding to the current signal and the ground plus a predetermined value.

5. The multi-phase motor control method of claim 4 , wherein the predetermined value is an internal constant or a sum of the internal constant and either a positive safety tolerance or a negative safety tolerance, and the internal constant is equal to an equivalent inductance of a wiring connected to the corresponding node divided by an equivalent resistance of the wiring.

6. The multi-phase motor control method of claim 1 , wherein the step of comparing the signal phase of the current signal with a reference phase of a desired target current signal to determine a phase difference comprises:
detecting a differential zero-crossing point between the current signal and another current signal corresponding to another node, wherein the differential zero-crossing point between the two current signals is an intersection between the two current signals;
determining a differential zero-crossing point between the desired target current signal and another desired target current signal which correspond to the two current signals, wherein the differential zero-crossing point between the two desired target current signals is an intersection between the two desired target current signals; and
calculating a time difference between the differential zero-crossing point between the two current signals and the differential zero-crossing point between the two desired target current signals to determine the phase difference.

7. The multi-phase motor control method of claim 6 , wherein the differential zero-crossing point between the two desired target current signals is equal to a differential zero-crossing point between two of the driving voltage signals corresponding to the two current signals plus a predetermined value, wherein the differential zero-crossing point between two of the driving voltage signals is an intersection between the two driving voltage signals.

8. The multi-phase motor control method of claim 7 , wherein the predetermined value is an internal constant or a sum of the internal constant and either a positive safety tolerance or a negative safety tolerance, and the internal constant is equal to an equivalent inductance of a wiring connected to the corresponding node divided by an equivalent resistance of the wiring.

9. The multi-phase motor control method of claim 1 , wherein the step of controlling a rotation speed of the rotor according to the comparing result comprises:
increasing the rotation speed of the rotor by increasing the phase switching frequencies of the driving voltage signals when the signal phase of the current signal is behind the reference phase of the desired target current signal; or
decreasing the rotation speed of the rotor by decreasing the phase switching frequencies of the driving voltage signals when the signal phase of the current signal is ahead of the reference phase of the desired target current signal.

10. The multi-phase motor control method of claim 1 , further comprising: activating the multi-phase motor; and performing the step of sensing the current signal corresponding to one of the plurality of nodes after it is confirmed that the rotor has started rotating.

11. The multi-phase motor control method of claim 1 , further comprising: activating the multi-phase motor; sensing the rotation speed of the rotor; and performing the step of sensing the current signal corresponding to one of the plurality of nodes after the rotation speed reaches a predetermined speed.

12. The multi-phase motor control method of claim 1 , further comprising:
controlling the phase switching frequency of at least one of the driving voltage signals according to the comparison result of comparing the signal phase of the current signal and the reference phase of the desired target current signal, such that a zero-crossing point of the current signal is close to or in phase with a zero-crossing point of the desired target current signal, wherein the zero-crossing point of the desired target current signal is set to be larger than a zero-crossing reference point plus an internal constant of the multi-phase motor; and
judging that the multi-phase motor is locked when the phase switching frequency of the driving voltage signal declines to a threshold value.

13. The multi-phase motor control method of claim 1 , further comprising:
controlling the phase switching frequency of at least one of the driving voltage signals according to the comparison result of comparing the signal phase of the current signal and the reference phase of the desired target current signal, such that a zero-crossing point of the current signal is close to or in phase with a zero-crossing point of the desired target current signal, wherein the zero-crossing point of the desired target current signal is set to be smaller than a zero-crossing reference point plus an internal constant of the multi-phase motor; and
judging that the multi-phase motor is locked when the phase switching frequency of the driving voltage signal rises to a threshold value.

14. A multi-phase motor control device, coupled to a multi-phase motor with a plurality of nodes respectively receiving a corresponding number of driving voltage signals to control a rotation of a rotor in the multi-phase motor, the multi-phase motor control device comprising:
a zero-crossing point detector, for receiving a current signal of one of the phases and detecting a zero-crossing point between the current signal and a ground;
a phase time calculator, for calculating a time difference between the zero-crossing point of the current signal and a zero-crossing point between a desired target current signal and the ground to obtain a phase difference between the current signal and the desired target current signal, and generating a frequency adjusting signal according to the phase difference; and
a driver, for adjusting a rotation speed of the rotor according to the frequency adjust

Assignees

• Lee Kuo-Chung
• Chang Wei-Hsu
• Chen An-Tung
• Wang Chun-Wen
• Richtek Technology Corp

Inventors

• Lee Kuo-Chung
• Chang Wei-Hsu
• Chen An-Tung
• Wang Chun-Wen

Classifications

• H02P6/182 Primary

  using back-emf in windings · CPC title

• H02P6/18 Primary

  without separate position detecting elements · CPC title

• H02P6/15

  Controlling commutation time · CPC title