High-efficiency drive due to power factor control of a permanent magnet synchronous motor

A drive system for a permanent magnet motor without a magnetic position detector is described. Generally, the position data of a magnet are obtained from the terminal voltage of the motor. In the newly developed method, the inverter DC-link current waveform provides the control signal for driving without a detector. Since the power factor of the motor is controlled at around 1.0, the motor runs at a higher efficiency than that of the conventional method. Therefore, this control method saves energy. Current pulsation induced by sudden load fluctuations has been studied, and its stabilization has been achieved. The principle and operation of the method, simulated characteristics, and experimental results are presented