MOTOR CONTROLLER AND ELECTRIC POWER STEERING APPARATUS

• US 20080203958A1
• Filed: 02/25/2008
• Published: 08/28/2008
• Est. Priority Date: 02/26/2007
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: SUZUKI, Hiroshi
• Granted Patent: US 7,843,154 B2
• Time in Patent Office: Days
• US Class Current: 318/629
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: H02P 21/06 Rotor flux based control involving the use of rotor position or rotor speed sensors
• CPC Class Codes: H02P 21/22 Current control, e.g. using a current control loop

Abstract

A second computing section executing a compensation control is provided with a third computing section computing a d-axis correction amount, and a fourth computing section computing a q-axis correction amount. The respective computing sections compute a d-axis correction coefficient and a q-axis correction coefficient corresponding to an rotation angle by referring to a map. The respective computing sections compute the d-axis correction amount and the q-axis correction amount on the basis of an arithmetic expression constituted by a first term obtained by multiplying a correction coefficient relating to an object axis by a q-axis current command value and a second term obtained by multiplying a correction coefficient relating to an auxiliary axis by a d-axis current command value. The second computing section computes a d-axis current command value and a q-axis current command value which do not generate a torque ripple caused by a distortion of an induced voltage waveform, by adding the d-axis correction amount and the q-axis correction amount to the d-axis current command value and the q-axis current command value.

Claims

1. A motor controller controlling a motor having a plurality of phases and provided with a plurality of motor coils each corresponding to one of the phases, the motor controller comprising:

computing means computing, as current command values for controlling the motor, a d-axis current command value and a q-axis current command value of a d/q coordinate system;

signal generating means converting detected current values of the phases of the motor into the d-axis current value and the q-axis current value of the d/q coordinate system, and generating a motor control signal by executing a feedback control in such a manner as to cause the d-axis current value and the q-axis current value to follow the computed d-axis current command value and q-axis current command value; and

correcting means correcting the d-axis current command value and the q-axis current command value in such a manner as to suppress a torque ripple caused by a distortion of an induced voltage waveform generated in the motor coil in each of the phases,

wherein the correcting means has, per rotation angle of the motor, correction coefficients each relating to one of the d axis and the q axis computed on the basis of a actually measured data of the induced voltage waveform,

wherein the correcting means executes the correction by adding, to the d-axis current command value and the q-axis current command value, a d-axis correction amount and a q-axis correction amount corresponding to the rotation angle and computed on the basis of each of the correction coefficients,

wherein the correcting means computes the d-axis correction amount by using an expression that consists of a first term obtained by multiplying the correction coefficient relating to the d-axis by the q-axis current command value and a second term obtained by multiplying the correction coefficient relating to the q-axis by the d-axis current command value, and

wherein the correcting means computes the q-axis correction amount by using an expression that consists of a first term obtained by multiplying the correction coefficient relating to the q-axis by the q-axis current command value and a second term obtained by multiplying the correction coefficient relating to the d-axis by the d-axis current command value.

2. The motor controller according to claim 1, wherein the correcting means computes the d-axis correction amount and the q-axis correction amount on the basis of the following expressions:

Expression

3. The motor controller according to claim 1, wherein the correcting means computes a speed gain for suppressing the generation of a torque ripple caused by an computation cycle difference between compensation control for suppressing a torque ripple caused by distortion of the induced voltage waveform and feedback control in the signal generating means.

4. The motor controller according to claim 3, wherein the correcting means computes a speed gain corresponding to the rotation angular velocity of the motor.

5. The motor controller according to claim 4, wherein, in the case where the rotation angular velocity of the motor exceeds a predetermined speed, the correcting means computes such a speed gain as to reduce the d-axis correction amount and the q-axis correction amount as the rotation angular velocity becomes higher.

6. The motor controller according to claim 4, wherein the correcting means sets the speed gain to 1 in the case where the absolute value of the rotation angular velocity is equal to or less than a first value, and sets the speed gain to 0 in the case where the absolute value of the rotation angular velocity is equal to or more than a second value, which is greater than the first value.

7. The motor controller according to claim 6, wherein, in the case where the absolute value of the rotation angular velocity is greater than the first value and smaller than the second value, the correcting means computes such a speed gain as to reduce the d-axis correction amount and the q-axis correction amount as the rotation angular velocity becomes higher.

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