Drive circuit for a permanent magnet motor

Patent metadata

Field	Value
Publication number	US-9755555-B2
Application number	US-201514822353-A
Country	US
Kind code	B2
Filing date	Aug 10, 2015
Priority date	Aug 8, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A drive circuit for an electric motor connected in series with an AC power source between a first node and a second node. The drive circuit includes a controllable bidirectional AC switch, an AC-DC conversion circuit connected in parallel with the controllable bidirectional AC switch between the first node and the second node, a position sensor configured to detect a position of a rotor of the motor, and a switch control circuit configured to control the controllable bidirectional AC switch to be conductive or non-conductive in a predetermined way, based on the position of the rotor and a polarity of the AC power source.

First claim

The invention claimed is:

1. A drive circuit for a permanent magnet motor comprising a stator and a permanent magnet rotor, the stator comprising a stator core and a stator winding wound on the stator core and adapted to be connected in series with an AC power source between a first node and a second node, the drive circuit comprising:
a controllable bidirectional AC switch connected between the first node and the second node;
an AC-DC conversion circuit connected in parallel with the controllable bidirectional AC switch between the first node and the second node;
a position sensor configured to detect a magnetic pole position of the permanent magnet rotor; and
a switch control circuit configured to control the controllable bidirectional AC switch to be switched between a switch-on state and a switch-off state in a predetermined way, based on the magnetic pole position of the permanent magnet rotor and the polarity of the AC power source such that the stator winding drives the rotor to rotate only in a fixed direction,
wherein the first node and the second node are short circuited when the controllable bidirectional AC switch is conductive and there is no current flowing through the AC-DC conversion circuit when the first node and the second node are short circuited by the controllable bidirectional AC switch.

2. The drive circuit of claim 1 , wherein the controllable bidirectional AC switch includes a TRIAC.

3. The drive circuit of claim 2 , wherein a first anode of the TRIAC is connected to the first node, a second anode of the TRIAC is connected to the second node, and a control electrode of the TRIAC is connected to the switch control circuit.

4. The drive circuit of claim 3 , wherein the AC-DC conversion circuit comprises a full wave rectifying circuit having a high voltage output terminal and a low voltage output terminal.

5. The drive circuit of claim 4 , wherein a zener diode is connected between the high voltage output terminal and the low voltage output terminal.

6. The drive circuit of claim 3 , wherein the AC-DC conversion circuit comprises a first diode and a second diode which are reversely connected in parallel between the first node and the second node respectively via a first resistor and a second resistor, a high voltage output terminal of the AC-DC conversion circuit is formed at a connection point of the first resistor and a cathode of the first diode, a low voltage output terminal of the AC-DC conversion circuit is formed at a connection point of the second resistor and an anode of the second diode, and the first diode and the second diode are zener diodes.

7. The drive circuit of claim 4 , wherein the AC-DC conversion circuit comprises a first resistor connected in series with the full wave bridge rectifier between the first node and the second node.

8. The drive circuit of claim 4 , wherein the full wave bridge rectifier comprises two rectifier branches connected in parallel, one of the two rectifier branches comprising a first diode and a third diode reversely connected in series, and the other of the two rectifier branches comprises a second diode and a fourth diode reversely connected in series, the high voltage output terminal of the AC-DC conversion circuit is formed at a connection point of a cathode of the first diode and a cathode of the third diode, and the low voltage output terminal of the AC-DC conversion circuit is formed at a connection point of an anode of the second diode and an anode of the fourth diode.

9. The drive circuit of claim 8 , wherein the second diode and the fourth diode are zener diodes.

10. The drive circuit of claim 4 , wherein the full wave bridge rectifier comprises two rectifier branches connected in parallel, one of the two rectifier branches comprises two silicon control rectifiers reversely connected in series, and the other of the two rectifier branches comprises a second diode and a fourth diode reversely connected in series, the high voltage output terminal of the AC-DC conversion circuit is formed at a connection point of cathodes of the two silicon control rectifiers, and the low voltage output terminal of the AC-DC conversion circuit is formed at a connection point of an anode of the second diode and an anode of the fourth diode.

11. The drive circuit of claim 10 , further comprising: a first signal terminal connected to cathodes of the two silicon control rectifiers and a second signal terminal connected to control terminals of the two silicon control rectifiers, wherein the first signal terminal is connected to a reference voltage; a control signal input from the second signal terminal ensures the two silicon control rectifiers to be switched between a switch-on state and a switch-off state in a predetermined way in a case that the drive circuit operates normally, or a control signal input from the second signal terminal enables the two silicon control rectifiers to be switched off in a case that the drive circuit fails.

12. The drive circuit of claim 1 , wherein the AC-DC conversion circuit has a high voltage output terminal and a low voltage output terminal, the switch control circuit comprises a first terminal connected to the high voltage output terminal, a second terminal connected to an output terminal of the position sensor, and a third terminal connected to the control electrode of the controllable bidirectional AC switch, the high voltage output terminal of the AC-DC conversion circuit is connected to a positive power supply terminal of the position sensor, and a low voltage output terminal of the AC-DC conversion circuit is connected to a negative power supply terminal of the position sensor.

13. The drive circuit of claim 12 , wherein a preset steering circuit is disposed between the third terminal of the switch control circuit and the control electrode of the controllable bidirectional AC switch, and the preset steering circuit comprises a first jumper switch connected between the third terminal and the control electrode of the controllable bidirectional AC switch, and a second jumper switch and an inverter connected in series which are connected in parallel with the first jumper switch between the third terminal and the control electrode.

14. The drive circuit of claim 12 , wherein the switch control circuit further comprises a third resistor, a fourth resistor, and a fifth diode and a sixth diode reversely connected in series between the output terminal of the position sensor and the control electrode of the controllable bidirectional AC switch; a cathode of the fifth diode is connected to the output terminal of the position sensor, and a cathode of the sixth diode is connected to the control electrode of the controllable bidirectional AC switch; one terminal of the third resistor is connected to the high voltage output terminal of the AC-DC conversion circuit, and the other terminal of the third resistor is connected to a connection point of an anode of the fifth diode and an anode of the sixth diode; and two terminals of the fourth resistor are connected to a cathode of the fifth diode and a cathode of the sixth diode respectively.

15. The drive circuit of claim 12 , wherein the switch control circuit further comprises a third resistor, a fifth diode, and a fourth resistor and a sixth diode connected in series between the output terminal of the position sensor and the control electrode of the controllable bidirectional AC switch; an anode of the sixth diode is connected to the control electrode of the controllable bidirectional AC switch; one terminal of the third resistor is connected to the high voltage output terminal of the AC-DC conversion circuit

Assignees

• Johnson Electric Sa

Inventors

• Li Yue
• Sun Chi Ping
• Liu Bao Ting
• Wang En Hui
• Xin Fei
• Yeung Shing Hin
• Yang Xiu Wen
• Cui yan yun
• Huang Shu Juan

Classifications

• H10W70/465

  Bumps or wires · CPC title

• H10W72/50

  Bond wires · CPC title

• H02P6/08

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• H02K11/05

  Rectifiers associated with casings, enclosures or brackets · CPC title

• H02P6/30 Primary

  Arrangements for controlling the direction of rotation (H02P6/22 takes precedence) · CPC title