MOTOR CONTROLLER

PURPOSE:To reduce vibrations caused by the difference between a generated torque and a load torque by a method wherein a fluctuation in the load torque is computed on the basis of information on a rotational position during one rotation of a rotor and a current and a torque are controlled. CONSTITUTION:A control part 20 computes the magnitude and the time of a load torque, during one rotation, which is applied to a compressor 13 on the basis of a positional signal, and it sends to a power-supply drive part 21 a signal which makes the output torque of a motor coincide with the detected load torque. The power-supply drive part 21 receives the signal. When the output torque is small, the drive part acts so as to increase a supply voltage to the motor and, when the output torque is large, the drive party acts so as to lower the supply voltage to the motor. Thereby, the output torque of the motor becomes nearly equal to the load torque which is changed during one rotation, a fluctuation in the rotational speed of a rotor due too a fluctuation in the load torque is eliminated, and vibrations are reduced.