To prevent a motor failure by overload operation in a sensor failure by limiting motor operation on the failure of the temperature sensor.

Load points are calculated depending on the operating state of a motor and the atmospheric temperature, and the drive control of the motor is performed based on an accumulation point calculated by accumulating the load points. A temperature correction point is acquired corresponding to the atmospheric temperature of the motor at the startup of the motor operation, and the acquired temperature correction point is used as an addition starting value. The accumulation point is calculated from this addition starting value and the accumulation value of the load points. When a failure of the temperature sensor is detected in acquiring the temperature correction point, a point equivalent to the upper limit, the temperature correction point in the upper limit of the motor working temperature, is used as the temperature correction point.

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