| 摘要 |
PURPOSE:To suppress the pulsating output torque of a motor by correcting the firing phase timing of a thyristor in the vicinity of zero current and approaching the instantaneous current of a load current to a current reference signal. CONSTITUTION:A level detector 34 inputs a current reference signal 21 and generates an output signal when the input value becomes lower than the prescribed ratio of the peak value of a sinusoidal wave. A phase control correcting circuit 35 receives a signal representing that the signal 21 becomes lower than the prescribed value from the detector 34, thereby correcting the phase control signal. In this manner, the followup delay to the sinusoidal wave current reference signal 21 of the load current immediately before switching can be prevented, thereby reducing the distortion of the waveform of the load current and reducing the pulsating output torque of a motor. |
