Three-phase high power factor AC/DC converter

A unidirectional three-phase AC/DC converter is proposed to obtain almost unity power factor, draw sinusoidal line currents and keep the DC-bus voltage constant. Two active switches and two power diodes are used in each converter leg to generate a three-level PWM waveform on the AC terminal voltages. The proposed converter has simpler circuit configuration compared with the conventional three-level PWM converters. The classical proportional-integral voltage controller and the hysteresis current controller are adopted in the control scheme to achieve DC-bus voltage regulation and line-current command tracking. A neutral-point voltage compensator is used to balance the neutral-point voltage due to load change. The validity and effectiveness of the proposed control algorithm is verified through simulations and experimental results.