| 摘要 |
The second torque value and a motor speed detected from the motor in operation are compared to an upper limit and lower limit of torque tolerance which is obtained based on the third torque value. Accordingly, if the third torque value exceeds the upper limit or underruns the lower limit of the torque tolerance, the motor is stopped in accordance with a difference between the third torque value and the torque tolerance. Consequently, since abnormality of the motor can be promptly and accurately detected within an entire speed range including a lower speed range, it is effective for protecting the motor or the machine equivalent of a load for the motor. |
