Motor control apparatus

• US 7,312,595 B2
• Filed: 05/30/2003
• Issued: 12/25/2007
• Est. Priority Date: 07/09/2002
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kamio, Shigeru, Fujiki, Kenichi
• Primary Examiner(s): Donovan, Lincoln
• Assistant Examiner(s): MCCLOUD, RENATA D
• Application Number:
  US10/448,409
• Publication Number:
  US 20040008002A1
• Time in Patent Office: 1,670 Days
• Field of Search: 318/701, 318/696, 318/685, 318/254, 318/640
• US Class Current: 318/701
• CPC Class Codes: G05B 19/4062 Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference
• CPC Class Codes: G05B 2219/42287 On feedback failure, use profile stored in memory during learning
• CPC Class Codes: G05B 2219/42322 Emit dummy pulses, detect loss of pulses, feedback failure, wire brake, short
• CPC Class Codes: H02P 6/12 Monitoring commutation; Providing indication of commutation failure

Abstract

Presence/absence of a failure in a feedback control system of a motor is monitored. When a failure is detected in the feedback control system, the motor is driven by switching to an open-loop control. During the open-loop control, the motor is rotated by sequentially switching the motor current supply phase without feeding back encoder count information. The position count is incremented or decremented every time the current supply phase is switched. When the position count has reached a target count, it is determined that the rotor has reached a target position, whereupon the open-loop control is finished.

Claims

1. A motor control apparatus comprising:

a single motor having a single rotor, a single stator, and at least two drive coils wound on the single stator and operable independently to rotate the single rotor;

an encoder for producing a pulse signal in synchronism with rotation of the single rotor of the motor, the motor rotating a control object;

feedback control means for performing a feedback control for rotating the rotor to a target position by detecting a rotation position of the rotor on a basis of a count of the pulse signal of the encoder and sequentially switching a current supply phase of the motor;

at least two systems each of which includes one of the drive coils of the motor and a drive circuit for separately driving the drive coil of the motor in that one of the at least two systems, wherein each of the at least two systems are independently operable from other of the at least two systems, the drive coil and the drive circuit of each system are provided so as to be able to rotate the rotor independently of the drive coil and the drive circuit of the other of the at least two systems, and the drive coil in each of the at least two independently operable systems includes a plurality of phase coils;

abnormality diagnosis means for determining presence or absence of an abnormality in the drive coil and/or the drive circuit of each system; and

open-loop control means for sequentially switching, when the abnormality diagnosis means has detected an abnormality in one of the at least two systems including a drive coil and a drive circuit, the current supply phase by supplying a drive signal to a drive circuit of a remaining system of the at least two systems by an open-loop control, counting pulses of the drive signal, and rotating the rotor to the target position on a basis of a resulting count.

2. The motor control apparatus according to claim 1,

wherein, during the open-loop control, the open-loop control means restricts a rotation speed of the rotor in accordance with a power source voltage that is supplied to the motor.

4. The motor control apparatus according to claim 1,

wherein, in driving the motor from a stop state by the open-loop control, the open-loop control means performs two-phase current supply as first current supply and thereafter performs one-phase current supply and two-phase current supply alternately.

5. The motor control apparatus according to claim 1,

wherein, in driving the motor from a stop state by the open-loop control, the open-loop control means sets a current supply time of a specific number of first current supply attempts so that the current supply time is longer than a current supply time of subsequent current supply attempts.

6. The motor control apparatus according to claim 1,

wherein, during the open-loop control, the open-loop control means sets a current supply time on a basis of at least one of a rotation speed of the rotor, a rotation amount of the rotor after a start of driving, an elapsed time from the start of the driving, a rotation amount to the target position, and load torque.

7. The motor control apparatus according to claim 1, further comprising:

an output shaft sensor for detecting a rotation position of an output shaft of the motor or position information correlated with the output shaft of the motor, wherein the open-loop control means finishes the open-loop control when a rotation position of the rotor inferred on a basis of a count of the drive signal during the open-loop control has reached the target position, the open-loop control means determines whether driving of the motor by the open-loop control has succeeded or failed on a basis of an output signal of the output shaft sensor, and, if the driving of the motor has failed, the open-loop control means drives the motor again by an open-loop control.

8. The motor control apparatus according to claim 7,

wherein, if the driving of the motor by the open-loop control has failed a specific number of times consecutively, the open-control means determines that the motor cannot be controlled by an open-loop control and turns off current supply of the motor.

9. The motor control apparatus according to claim 7,

wherein the open-loop control means infers an initial position of the rotor at a start of the open-loop control on the basis of the output signal of the output shaft sensor, and infers a rotation position of the rotor during the open-loop control on a basis of the initial position of the rotor inferred by the open-loop control means and the count of the drive signal.

10. The motor control apparatus according to claim 1,

wherein the motor is a switched reluctance motor.

11. The motor control apparatus according to claim 1,

wherein the control object is a position switching device for switching between a parking position and another position of a vehicle.

3. A motor control apparatus comprising:

an encoder for producing a pulse signal in synchronism with rotation of a single rotor of a motor that rotates a control object;

feedback control means for performing a feedback control for rotating the rotor to a target position by detecting a rotation position of the rotor on a basis of a count of the pulse signal of the encoder and sequentially switching a current supply phase of the motor;

at least two systems each of which includes a drive coil of the motor and a drive circuit for separately driving the drive coil of the motor in that one of the at least two systems, wherein, each of the at least two systems are independently operable from other of the at least two systems and the drive coil and the drive circuit of each system are provided so as to be able to rotate the rotor independently of the drive coil and the drive circuit of the other of the at least two systems;

abnormality diagnosis means for determining presence or absence of an abnormality in the drive coil and/or the drive circuit of each system; and

open-loop control means for sequentially switching, when the abnormality diagnosis means has detected an abnormality in one of the at least two systems including a drive coil and a drive circuit, the current supply phase by supplying a drive signal to a drive circuit of a remaining system of the at least two systems by an open-loop control, counting pulses of the drive signal, and rotating the rotor to the target position on a basis of a resulting count;

wherein the abnormality diagnosis means comprises means for detecting a disconnection in the drive coils, and wherein when a disconnection is detected in the drive coil of one system of the at least two systems, the open-loop control means supplies a drive signal to the drive circuit of a remaining system of the at least two systems so that a rotation speed of the rotor becomes lower than when an abnormality other than a disconnection is detected.

12. A control method for a single motor having a single rotor, a single stator, and at least two drive coils wound on the single stator and operable independently to rotate the single rotor, and at least two independently operable systems including the drive coils and drive circuits for separately driving the drive coils, each independently operable system being able to rotate the single rotor of the motor independently of any other of the at least two independently operable systems, the method comprising:

supplying electric currents to each of the drive coils of the independently operable systems by each of the drive circuits of the independently operable systems, respectively, to drive the motor to a target position by rotating the rotor of the motor, wherein each of the drive coils of the independently operable systems includes a plurality of phase coils;

determining whether an abnormality is present in any of the drive circuits and/or any of the drive coils with respect to each of the independently operable systems; and

supplying the electric current, when the abnormality is determined in one of the independently operable systems, to the drive coil of an other one of the independently operable systems to drive the motor to the target position without supplying the electric current to the drive coil of the one of the independently operable systems.

13. The control method according to claim 12, wherein:

determining an abnormality includes detecting the current flowing in the phase coils in each of the independently operable systems separately from each of an other of the phase coils in an other of the independently operable systems and determining the abnormality based on the detected current.

14. The method according to claim 12, further comprising, when the abnormality is determined, restricting a rotation speed of the rotor in accordance with a power source voltage that is supplied to the motor using an open loop control.

16. The method according to claim 12, further comprising, when the abnormality is determined, driving the motor from a stop state by an open-loop control, the open-loop control performing two-phase current supply as first current supply and thereafter performing one-phase current supply and two-phase current supply alternately.

17. The method according to claim 12, further comprising, when the abnormality is determined, driving the motor from a stop state by an open-loop control, the open-loop control setting a current supply time of a specific number of first current supply attempts so that the current supply time is longer than a current supply time of subsequent current supply attempts.

18. The method according to claim 12, further comprising, when the abnormality is determined, setting a current supply time on a basis of at least one of a rotation speed of the rotor, a rotation amount of the rotor after a start of driving, an elapsed time from the start of the driving, a rotation amount to the target position, and load torque.

19. The method according to claim 12, further comprising:

detecting a rotation position of an output shaft of the motor or position information correlated with the output shaft of the motor, finishing open-loop control when a rotation position of the rotor inferred on a basis of a count of a drive signal during the open-loop control has reached a target position, determining whether driving of the motor by the open-loop control has succeeded or failed on a basis of an output signal of an output shaft sensor, and, if the driving of the motor has failed, driving the motor again by an open-loop control.

20. The method according to claim 19, further comprising if the driving of the motor by the open-loop control has failed a specific number of times consecutively, determining that the motor cannot be controlled by an open-loop control and turning off current supply of the motor.

21. The method according to claim 19, further comprising inferring an initial position of the rotor at a start of the open-loop control on the basis of the output signal of the output shaft sensor, and inferring a rotation position of the rotor during the open-loop control on a basis of the initial position of the rotor inferred at a start of the open-loop control and the count of the drive signal.

15. A control method for a motor having at least two independently operable systems of drive coils and drive circuits for separately driving the drive coils, each independently operable system being able to rotate a rotor of the motor independently of any other of the at least two independently operable systems, the method comprising:

supplying electric currents to each of the drive coils of the independently operable systems by each of the drive circuits of the independently operable systems, respectively, to drive the motor to a target position;

determining whether an abnormality is present in any of the drive circuits and/or any of the drive coils with respect to each of the independently operable systems; and

supplying the electric current, when the abnormality is determined in one of the independently operable systems, to the drive coil of an other one of the independently operable systems to drive the motor to the target position without supplying the electric current to the drive coil of the one of the independently operable systems;

wherein determining an abnormality includes detecting a disconnection in the at least one of the drive coils, and wherein when a disconnection is detected in the drive coil of the one of the independently operable systems, a drive signal is supplied to the drive circuit of an other one of the independently operable systems so that a rotation speed of the rotor becomes lower than when an abnormality other than a disconnection is detected.