Single phase brushless DC motor and method of adjusting output phase thereof

Patent metadata

Field	Value
Publication number	US-9780705-B2
Application number	US-201615004991-A
Country	US
Kind code	B2
Filing date	Jan 24, 2016
Priority date	Nov 18, 2015
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A single phase brushless DC motor comprises a Hall effect sensor, a coil assembly and a motor control circuit which generating a driving signal to guide a coil current flowing through the coil assembly. The Hall effect sensor senses the magnetic pole of the rotor to accordingly generate a Hall effect signal. The motor control circuit outputs a current polarity reverse signal according to the voltage at one end of the coil assembly. The time when the current polarity reverse signal is generated corresponds to the polarity reverse time of the coil current. The motor control circuit adjusts the phase of the driving signal according to the polarity reverse time of the Hall effect signal and the time when the current polarity reverse signal is generated to synchronize the phase of the back emf of the single phase brushless DC motor with the phase of the coil current.

First claim

What is claimed is:

1. A single phase brushless DC motor, comprising:
a Hall effect sensor sensing a position of the magnetic pole of a rotor of the motor to accordingly generate a Hall effect signal;
a coil assembly; and
a motor control circuit comprising:
a coil switching unit coupled to the coil assembly;
a driving unit generating a driving signal to drive the coil switching unit to guide a coil current flowing through the coil assembly;
a coil voltage converting unit coupled to the coil assembly and the coil switching unit and detecting the voltage at one end of the coil assembly to accordingly output a phase voltage transition signal;
a reverse current polarity detection unit receiving the phase voltage transition signal to accordingly output a current polarity reverse signal, wherein the time when the current polarity reverse signal is generated corresponds to the polarity reverse time of the coil current;
a phase error detection unit receiving the Hall effect signal and the current polarity reverse signal, and outputting a phase error signal according to the time interval between the polarity reverse time of the Hall effect signal and the time when the current polarity reverse signal is generated;
a phase control unit receiving the Hall effect signal and the phase error signal to accordingly output a phase compensation commutation signal; and
a logic unit receiving the phase compensation commutation signal to accordingly adjust the phase of the driving signal to synchronize the phase of the back emf of the single phase brushless DC motor with the phase of the coil current.

2. The motor of claim 1 , wherein the coil switching unit comprises a first switching element, a second switching element, a third switching element and a fourth switching element, a first end of the coil assembly is coupled to the first switching element and the third switching element, a second end of the coil assembly is coupled to the second switching element and the fourth switching element.

3. The motor of claim 2 , wherein the reverse current polarity detection unit receives the phase voltage transition signal related to the voltage detected at the second end and outputted by the coil voltage converting unit to accordingly output the current polarity reverse signal when the driving signal controls the first switching element to be cut off, the second switching element to conduct, the third switching element to conduct and the fourth switching element to be cut off and the second switching element receives a PWM signal out of the duty cycle.

4. The motor of claim 2 , wherein the reverse current polarity detection unit receives the phase voltage transition signal related to the voltage detected at the first end and outputted by the coil voltage converting unit to accordingly output the current polarity reverse signal when the driving signal controls the first switching element to conduct, the second switching element to be cut off, the third switching element to be cut off and the fourth switching element to conduct, and the first switching element receives a PWM signal out of the duty cycle.

5. The motor of claim 2 , wherein the reverse current polarity detection unit receives the phase voltage transition signal related to the voltage detected at the first end and outputted by the coil voltage converting unit to accordingly output the current polarity reverse signal when the driving signal controls the first switching element to be cut off, the second switching element to conduct, the third switching element to conduct and the fourth switching element to be cut off, and the third switching element receives a PWM signal out of the duty cycle.

6. The motor of claim 2 , wherein the reverse current polarity detection unit receives the phase voltage transition signal related to the voltage detected at the second end and outputted by the coil voltage converting unit to accordingly output the current polarity reverse signal when the driving signal controls the first switching element to conduct, the second switching element to be cut off, the third switching element to be cut off and the fourth switching element to conduct, and the fourth switching element receives a PWM signal out of the duty cycle.

7. The motor of claim 1 , wherein the motor control circuit further comprises a compensation adjusting unit coupled between the phase error detection unit and the phase control unit, and the compensation adjusting unit receives the phase error signal to accordingly adjust the compensation magnitude for the phase compensation commutation signal of the phase control unit.

8. A method of adjusting output phase of motor for a single phase brushless DC motor, wherein the single phase brushless DC motor comprises a coil assembly, a Hall effect sensor and a motor control circuit, the motor control circuit comprises a coil switching unit, the coil switching unit is coupled to the coil assembly and receives a driving signal to guide a coil current flowing through the coil assembly, comprising:
sensing a position of the magnetic pole of the rotor of the single phase brushless DC motor to generate a Hall effect signal by the Hall effect sensor;
generating a current polarity reverse signal according to a voltage at one end of the coil assembly and the duration of the voltage kept at a high level ranging from VCC to VCC+V F by the motor control circuit, wherein V F is an applied voltage of a freewheeling diode; and
adjusting a phase of the driving signal according to the time interval between the polarity reverse time of the Hall effect signal and the time when the current polarity reverse signal is generated by the motor control circuit to synchronize a phase of the back emf of the single phase brushless DC motor with a phase of the coil current and synchronize a phase of the current polarity reverse signal with a phase of the Hall effect signal.

9. The method of claim 8 , wherein the step of adjusting the phase of the driving signal comprises:
determining whether the polarity reverse time of the Hall effect signal lags the time when the current polarity reverse signal is generated by the motor control circuit;
accordingly advancing the phase of the driving signal by the motor control circuit if the polarity reverse time of the Hall effect signal is earlier than the time when the current polarity reverse signal is generated; and
accordingly delaying the phase of the driving signal by the motor control circuit if the polarity reverse time of the Hall effect signal is later than the time when the current polarity reverse signal is generated.

Assignees

• Delta Electronics Inc

Inventors

• Lin Yi-Fan
• Lin Chien-Sheng
• Tang Chung-Hung
• Chiu Chun-Lung

Classifications

• H02P6/16 Primary

  Circuit arrangements for detecting position · CPC title

• H02P6/157

  wherein the commutation is function of electro-magnetic force [EMF] · CPC title

• H02P6/26 Primary

  Arrangements for controlling single phase motors · CPC title

• H02K29/08 Primary

  using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) · CPC title