A novel filter design for suppression of high voltage gradient in voltage-fed PWM inverter

This paper proposes a new filter topology that suppresses the high voltage gradient (dv/dt) in AC motor terminals when a cable feeding a motor is very long. By using the proposed filter in the inverter terminal, the rising and the falling edge of the PWM waveform of the inverter are smoothed, resulting in less voltage gradient to the AC motor. The effectiveness of the proposed filter is compared to that of the conventional scheme and its effectiveness is verified by computer simulation, as well as by prototype experiments.