Drive device for a brushless motor

• US 7,719,217 B2
• Filed: 02/12/2008
• Issued: 05/18/2010
• Est. Priority Date: 02/15/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kimura, Azuma, Yokota, Youji
• Primary Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US12/029,881
• Publication Number:
  US 20080211439A1
• Time in Patent Office: 826 Days
• Field of Search: 318/400.21, 318/400.22, 318/430, 318/432, 318/490, 318/254, 701/41
• US Class Current: 318/400.21
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G01R 31/50 Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections testing of sparking plugs H01T13/58
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02P 29/032 Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
• CPC Class Codes: H02P 6/10 Arrangements for controlling torque ripple, e.g. providing reduced torque ripple

Abstract

A drive device for a brushless motor executes an abnormality diagnosis (disconnection/short-circuit) of a motor side circuit. In detecting abnormality of the motor side circuit, the drive device includes a terminal voltage monitor circuit that monitors a terminal voltage of an output terminal that is connected to a motor terminal of respective phases. A microcomputer starts abnormality diagnosis under a condition where the motor is stopped, and an object to be driven has normally operated at the time of driving the motor. For executing the abnormality diagnosis, the microcomputer turns on/off only a transistor of the drive circuit of one phase in a state where all of transistors are turned off, and acquires monitor signals to execute the abnormality diagnosis based on signal levels of the monitor signals.

Claims

1. A drive device for a brushless motor, comprising:

a plurality of drive circuits that are connected to a plurality of motor terminals of the brushless motor, respectively, each drive circuit having a pair of switching elements that connects a power supply fine of a DC power supply and a ground line to the motor terminals, respectively;

a plurality of terminal voltage detecting means that detects terminal voltages of the respective motor terminals, respectively; and

abnormality diagnosing means that executes abnormality diagnosis of a motor side circuit after turning off all of the switching elements in the plurality of drive circuits,

wherein the abnormality diagnosing means applies a voltage to one of the motor terminals after turning off the switching elements by turning on the switch element on a power supply line side that is disposed in one of the plurality of drive circuits, and takes in the terminal voltages of the respective motor terminals from the respective terminal voltage detecting means as high or low level signals, thereby executing the abnormality diagnosis based on a signal level of the taken terminal voltages.

2. The drive device for a brushless motor according to claim 1, wherein:

the brushless motor is a three-phase brushless motor, which includes a three star-connected windings; and

the switching elements of each of the drive circuits are connected in a half-bridge configuration.

3. The drive device for a brushless motor according to claim 1, wherein:

the abnormality diagnosing means turns on only the switch element on a power supply line side that is disposed in one of the plurality of drive circuits, thereby applying the voltage to one of the motor terminals.

4. A drive device for a brushless motor, comprising:

a plurality of drive circuits that are connected to a plurality of motor terminals of the brushless motor, respectively, each drive circuit having have a pair of switching elements that connects a power supply fine of a DC power supply and a ground line to the motor terminals, respectively;

a plurality of terminal voltage detecting means that detects terminal voltages of the respective motor terminals, respectively;

a rotation sensor that is disposed in the brushless motor;

checking means that checks whether the brushless motor has stopped rotating based on the detection signal of the rotation sensor; and

abnormally diagnosing means that executes abnormality diagnosis of a motor side circuit after turning off all of the switching elements in the plurality of drive circuits,

wherein the abnormality diagnosing means applies a voltage to one of the motor terminals after turning off the switching elements and takes in the terminal voltages of the respective motor terminals from the respective terminal voltage detecting means as high or low level signals, thereby executing the abnormality diagnosis based on a signal level of the taken terminal voltages, when the checking means determines that the brushless motor has stopped rotating.

5. The drive device for a brushless motor according to claim 4, wherein:

the abnormality diagnosing means turns on the switch element on a power supply line side that is disposed in one of the plurality of drive circuits, thereby applying the voltage to one of the motor terminals.

6. The drive device for a brushless motor according to claim 4, wherein:

the brushless motor is a three-phase brushless motor, which includes a three star-connected windings; and

the switching elements of each of the drive circuits are connected in a half-bridge configuration.

7. The drive device for a brushless motor according to claim 4, wherein:

the abnormality diagnosing means turns on only the switch element on a power supply line side that is disposed in one of the plurality of drive circuits, thereby applying the voltage to one of the motor terminals.

8. A drive device for a brushless motor, comprising:

a plurality of drive circuits that are connected to a plurality of motor terminals of the brushless motor, respectively, each drive circuit having have a pair of switching elements that connects a power supply line of a DC power supply and a ground line to the motor terminals, respectively;

a plurality of terminal voltage detecting means that detects terminal voltages of the respective motor terminals, respectively;

checking means that checks whether an object to be driven connected to a motor shaft of the brushless motor has operated normally at the time of driving the brushless motor; and

abnormality diagnosing means that executes abnormality diagnosis of a motor side circuit after turning off all of the switching elements in the plurality of drive circuits,

wherein the abnormality diagnosing means applies a voltage to one of the motor terminals after turning off the switching elements and takes in the terminal voltages of the respective motor terminals from the respective terminal voltage detecting means as high or low level signals, thereby executing the abnormality diagnosis based on a signal level of the taken terminal voltages, when the checking means determines that the object to be driven has operated normally.

9. The drive device for a brushless motor according to claim 8, further comprising:

a rotation sensor that is disposed in the brushless motor,

wherein the checking means further checks whether the brushless motor has stopped rotating based on the detection signal of the rotation sensor, and

wherein the abnormality diagnosing means applies a voltage to one of the motor terminals after turning off the switching elements and takes in the terminal voltages of the respective motor terminals from the respective terminal voltage detecting means, thereby executing the abnormality diagnosis based on the taken terminal voltages, when the checking means further determines that the brushless motor has stopped rotating.

10. The drive device for a brushless motor according to claim 8, wherein:

the abnormality diagnosing means turns on the switch element on a power supply line side that is disposed in one of the plurality of drive circuits, thereby applying the voltage to one of the motor terminals.

11. The drive device for a brushless motor according to claim 8, wherein:

the brushless motor is a three-phase brushless motor, which includes a three star-connected windings; and

the switching elements of each of the drive circuits are connected in a half-bridge configuration.

12. The drive device for a brushless motor according to claim 8, wherein:

the abnormality diagnosing means turns on only the switch element on a power supply line side that is disposed in one of the plurality of drive circuits, thereby applying the voltage to one of the motor terminals.