Motor driving control method and motor driving control apparatus

A motor driving control apparatus comprising:

• a three-phase bridge circuit connected to a three-phase brushless motor provided in a vehicle for steering assist;
• a motor control circuit for making the three-phase bridge circuit output three-phase alternating currents as motor drive current, by performing PWM control in a triangle comparison method based on a command value determined in dependence on a steering angle, a vehicle speed, and other driving states;
• shunt resistances for providing current-feedback of the motor drive current;
• and
• steering state judgment means for judging whether the steering manipulation is at the time of an ordinary steering in which the steering angular velocity is lower than a predetermined reference steering angular velocity or at the time of a quick steering in which the steering angular velocity is higher than the reference steering angular velocity;
• and
• wherein:
• at the time of the ordinary steering, the motor control circuit detects actual motor drive currents by the respective shunt resistances with the peak level of each of the three-phase alternating current command waves being limited so that the interval between a pair of intersection points of a peak area of each of the three-phase alternating current command waves with a peak point neighborhood of a triangle wave, which waves are compared in the triangle comparison method, becomes longer than the sum of a current detection time by the shunt resistances and a dead time for switching, and
• at the time of the quick steering, the motor control circuit infers an actual motor drive current from a back electromotive voltage and an applying voltage in the three-phase brushless motor instead of the current detections by the shunt resistances and mitigates the limitation on the peak level of each of the three-phase alternating current command waves by permitting the interval between the pair of intersection points to become approximately the same length as the dead time.

A motor driving control apparatus comprising:

• a three-phase bridge circuit connected to a three-phase brushless motor provided in a vehicle for steering assist;
• a motor control circuit for making the three-phase bridge circuit output three-phase alternating currents as motor drive current, by performing PWM control in a triangle comparison method based on a command value determined in dependence on a steering angle, a vehicle speed, and other driving states;
• shunt resistances for providing current-feedback of the motor drive current;
• steering state judgment means for judging whether the steering manipulation is at the time of an ordinary steering in which the steering angular velocity is lower than a predetermined reference steering angular velocity or at the time of a quick steering in which the steering angular velocity is higher than the reference steering angular velocity;
• current detection means provided in the motor control circuit and configured to operate at the time of the ordinary steering for detecting actual motor drive currents by the respective shunt resistances with the peak level of each of the three-phase alternating current command waves being limited so that the interval between a pair of intersection points of a peak area of each of the three-phase alternating current command waves with a peak point neighborhood of a triangle wave, which waves are compared in the triangle comparison method, becomes longer than the sum of a current detection time by the shunt resistances and a dead time for switching;
• and
• inference means provided in the motor control circuit and configured to operate at the time of the quick steering, for inferring an actual motor drive current from a back electromotive voltage and an applying voltage in the three-phase brushless motor instead of detecting the actual motor drive currents by the respective shunt resistances;
• and
• limitation mitigation means provided in the motor control circuit and configured to operate at the time of the quick steering, for mitigating the limitation on the peak level of each of the three-phase alternating current command waves by permitting the interval between the pair of intersection points to become approximately the same length as the dead time.