| 摘要 |
PROBLEM TO BE SOLVED: To enhance the degree of freedom for time setting required for determining a motor current by providing motor driving direction control means which makes the motor driving direction limited area variable in accordance with the motor current value after filter treatment of the detected motor current using different charging/discharging time constants. SOLUTION: The filter time constant of the filter treatment means in the motor drive limiting means 5 is switched depending on the time for increasing or decreasing current. For example, the motor current when releasing the wheel is limited to the level in which the motor 2 cannot rotate, that is, equal to or lower than the torque loss of the motor 2, or equal to or lower than the torque obtained by adding the torque loss of the motor 2 and the loss torque of a gear portion connected to the steering such that the revolution of the motor 2 is suppressed for securing safety. Alternatively, the charging time constant of the filter when increasing the motor current is reduced and the discharging time constant of the filter when decreasing the motor current is elongated so as to increase the motor driving direction limit when the steering torque is at around the neutral position. By this, the motor driving direction can be limited quickly in response to the abnormal state. |
