Motor controller and electric power steering apparatus

• US 7,859,206 B2
• Filed: 02/25/2008
• Issued: 12/28/2010
• Est. Priority Date: 02/26/2007
• Status: Expired due to Fees

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: Suzuki, Hiroshi
• Primary Examiner(s): Benson; Walter
• Assistant Examiner(s): Paul; Antony M
• Application Number:
  US12/036,670
• Publication Number:
  US 20080203963A1
• Time in Patent Office: 1,037 Days
• Field of Search: 318/628, 318/700, 318/400.02, 318/400.14, 318/400.21, 318/400.23, 318/400.26, 318/400.35, 318/727, 318/430, 318/432, 318/437, 318/799, 318/811, 180/271, 180/412, 180/443, 180/447
• US Class Current: 318/400.02
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: B62D 5/0484 for reaction to failures, e.g. limp home
• CPC Class Codes: B62D 5/0487 detecting motor faults B62D5/0496 takes precedence

Abstract

A microcomputer includes a calculating section calculating a d-axis electric current command value and a q-axis electric current command value and a signal generating section. The signal generating section generates a motor control signal through feedback control in a d-q coordinate system based on the d-axis electric current command value and the q-axis electric current command value. The microcomputer also has an anomaly determining section, which detects an anomaly if a failure of electric current flow has occurred in any one of phases of a motor. If the anomaly is detected, the microcomputer produces a motor control signal instructing to use, as electric current flowing phases, two phases other than the phase with the failed electric current flow. At this stage, the microcomputer calculates the d-axis electric current command value in such a manner as to produce the q-axis electric current value corresponding to the q-axis electric current command value except for values at angles corresponding to the phase with the failed electric current flow.

Claims

1. A motor controller having signal output means outputting a motor control signal and a driver circuit supplying a three phase drive power to a motor in response to the motor control signal, wherein the signal output means includes:

calculating means calculating, as electric current command values, a d-axis electric current command value and a q-axis electric current command value of a d/q coordinate system;

signal generating means generating the motor control signal by converting respective detected phase electric current values of the motor to a d-axis electric current value and a q-axis electric current value of the d/q coordinate system and performing feedback control in such a manner that the d-axis electric current value and the q-axis electric current value follow the calculated d-axis electric current command value and the calculated q-axis electric current command value, respectively; and

detecting means, wherein, if a failure of electric current flow occurs in any one of phases of the motor, the detecting means is capable of detecting the anomaly,

wherein, if the anomaly is detected, the signal output means outputs the motor control signal instructing to use, as electric current flowing phases, the phases other than the phase with the anomaly, and

wherein, when the anomaly is detected, the calculating means calculates the d-axis electric current command value in such a manner that a q-axis electric value corresponding to the q-axis electric current command value is generated, except that the q-axis electric value does not correspond to the q-axis electric current command value for a rotation angle corresponding to the phase with the anomaly.

2. The motor controller according to claim 1, wherein, when the anomaly is detected, the calculating means calculates the d-axis electric current command value that changes in a monotonically nondecreasing manner or a monotonically nonincreasing manner in correspondence with the sign of the q-axis electric current command value with a predetermined rotation angle as an asymptotic line.

3. The motor controller according to claim 1, wherein, when the anomaly is detected, the calculating means calculates the d-axis electric value command value that changes along a tangential curve with a predetermined rotation angle as an asymptotic line.

4. The motor controller according to claim 1, wherein, when the anomaly is detected, the calculating means calculates the d-axis electric current command value in accordance with the phase with the anomaly, using the following expressions:

if the failure of electric current flow has occurred in the U phase;

I_d*=I_q*×

tan θ

 

 

(1)

if the failure of electric current flow has occurred in the V phase;

5. The motor controller according to claim 1, wherein the calculating means performs a guard procedure that restricts the d-axis electric current command value to a predetermined range.

6. The motor controller according to claim 1, wherein the signal output means detects the anomaly in any one of phases based on respective phase electric current values of the motor, a rotation angular velocity of the motor, and a duty command value of each of the phases.

7. The motor controller according to claim 6, wherein the signal output means determines that a failure of electric current flow has occurred in any one of the phases if the phase electric current value of the phase is smaller than or equal to a predetermined value, the rotation angular velocity of the phase is smaller than or equal to a predetermined value, and a duty command value of the phase is outside a predetermined range.

8. The motor controller according to claim 7, wherein the signal output means determines that a failure of electric current flow has occurred in any one of the phases if the phase is continuously maintained for a predetermined period or more in a state in which the phase electric current value of the phase is smaller than or equal to the predetermined value, the rotation angular velocity of the phase is smaller than or equal to the predetermined value, and the duty command value of the phase is outside the predetermined range.

9. The motor controller according to claim 7, wherein, the predetermined value of the phase electric current value is set to a value close to zero and the predetermined value of the rotation angular velocity is set to a value corresponding to a maximum number of rotation of the motor.

10. An electric power steering apparatus comprising the motor controller according to claim 1.