Control circuit and motor device

Patent metadata

Field	Value
Publication number	US-2016006342-A1
Application number	US-201514856946-A
Country	US
Kind code	A1
Filing date	Sep 17, 2015
Priority date	Mar 26, 2010
Publication date	Jan 7, 2016
Grant date	—

Abstract

A control circuit includes: an input terminal for receiving an input AC voltage; a voltage decreasing unit for decreasing the input AC voltage; an A-D converter for converting the decreasing AC voltage to a DC voltage; a driving unit for receiving the DC voltage and to driving a motor, a detecting unit for detecting the DC voltage; and a current shunt unit configured to be conductive to lower the DC voltage at the output terminal of the A-D converter to a voltage which is less than a threshold voltage when the detecting signal indicates that the detected DC voltage exceeds the threshold value. A motor device includes the control circuit and a motor.

First claim

1 . A control circuit comprising:
an input terminal for receiving an input AC voltage; a voltage decreasing unit for decreasing the input AC voltage; an A-D converter for converting the decreasing AC voltage output from the voltage decreasing unit to a DC voltage; a driving unit for receiving the DC voltage output from the A-D converter and outputting voltage to drive a motor, a detecting unit for detecting the DC voltage and to produce a detecting signal indicating whether the detected DC voltage exceeds a predetermined threshold value; and a current shunt unit configured to be conductive to lower the DC voltage at the output terminal of the A-D converter to a voltage which is less than the threshold voltage when the detecting signal indicates that the detected DC voltage exceeds the threshold value, and to be non-conductive to allow the A-D converter output a DC voltage for the driving unit when the detecting signal indicates that the detected DC voltage is lower than the threshold value.

2 . The control circuit of claim 1 , wherein the voltage decreasing unit comprises a capacitor unit connected between the input terminal and the input of the A-D converter.

3 . The control circuit of claim 2 , wherein the capacitor unit comprises at least a fixed capacitor electrically connected between the input terminal and the A-D converter.

4 . The control circuit of claim 2 , wherein the capacitor unit is an adjustable capacitor unit which comprises at least two fixed capacitors with fixed capacitance and a control unit for respectively and selectively, electrically connecting the at least two fixed capacitors between input terminal and the A-D converter.

5 . The control circuit of claim 4 , wherein the control unit comprises at least two switches which are respectively electrically connected in series with the at least two fixed capacitors, and each switch and a corresponding capacitor form a switching capacitor and the at least two switching capacitors are electrically connected in parallel with each other; when a switch is closed or conductive, its corresponding capacitor is electrically connected between the AC power supply and the A-D converter; when a switch is open or non-conductive, its corresponding capacitor is electrically disconnected from the circuit with the AC power supply.

6 . The control circuit of claim 3 or 1 , wherein the over-voltage detecting unit comprises a first Zener diode and the current shunt unit comprises a NPN transistor, the anode of the first Zener diode is electrically connected with the positive output of the A-D converter and the cathode of the first Zener diode is electrically with the base of the NPN transistor, the collector of the NPN transistor is connected with the positive output of the A-D converter, and the emitter of the NPN transistor is connected with the negative output of the A-D converter.

7 . The control circuit of claim 6 , wherein the negative output of the A-D converter is connected with ground.

8 . The control circuit of claim 1 , further comprising a low-voltage generating unit configured to generate a lower DC voltage from the output DC voltage of the A-D converter.

9 . The control circuit of claim 8 , wherein the low-voltage generating unit comprises a resistor and a second Zener diode, one end of the resistor is electrically connected with the positive output of the A-D converter, the other end is electrically connected with the cathode of the second Zener diode, and the anode of the second Zener diode is electrically connected with the negative output of the A-D converter.

10 . The control circuit of claim 9 , wherein a filtering capacitor electrically connected in parallel with the second Zener diode is arranged to make smooth or to stabilize the output of the low-voltage generating unit at the cathode of the second Zener diode.

11 . The control circuit of claim 8 , wherein the driving unit comprises an inverter, a controller and a position detecting unit, the position detecting unit is configured to detect the position of the rotor of a BLDC motor and output a corresponding position signal, the controller is also powered by the lower DC voltage and configured to respond to the position signal to output a corresponding commutation signal, and the inverter is powered by the DC voltage output from the A-D converter and configured to respond to the commutation signal to control the power to the motor.

12 . The control circuit of claim 8 , wherein the A-D converter, the driving unit, the over-voltage detecting unit, the current shunt unit and the low-voltage generating unit are arranged on a single printed circuit board.

13 . The control circuit of claim 12 , wherein the voltage decreasing unit is mechanically independent from the printed circuit board but electrically connected with the printed circuit board.

14 . The control circuit of claim 1 , the threshold voltage is substantially equal to the nominal voltage of the input terminal.

15 . A motor device comprising a motor and the control circuit of claim 1 , wherein the motor is driven by the driving unit.

16 . The motor device of claim 15 , wherein the motor is a BLDC motor.

17 . The motor device of claim 16 , wherein the motor is a single-phase BLDC motor.

18 . The control circuit of claim 4 , wherein the over-voltage detecting unit comprises a first Zener diode and the current shunt unit comprises a NPN transistor, the anode of the first Zener diode is electrically connected with the positive output of the A-D converter and the cathode of the first Zener diode is electrically with the base of the NPN transistor, the collector of the NPN transistor is connected with the positive output of the A-D converter, and the emitter of the NPN transistor is connected with the negative output of the A-D converter.

19 . The control circuit of claim 18 , wherein the negative output of the A-D converter is connected with ground.

Assignees

• Johnson Electric Sa

Inventors

• Wang En Hui
• Xin Fei
• Sun Chi Ping
• Zhang Ming Li

Classifications

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02P6/14

  Electronic commutators · CPC title

• H02M7/066 Primary

  particular circuits having a special characteristic · CPC title

• H02M7/2176

  comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output · CPC title

• H02H7/1222

  responsive to abnormalities in the input circuit, e.g. transients in the DC input · CPC title