Three-phase high power factor rectifier with unidirectional power flow

This paper presents a three-phase multilevel rectifier with reduced power switches to achieve high power factor, low harmonics and high voltage capability. In the conventional three-phase neutral point clamped rectifiers, twelve power switches are used to draw the sinusoidal line currents with unity power factor. The mains drawback of these systems is the large number of power switches used in the circuits. Only six power switches with voltage rating of half DC-link are adopted in the proposed multilevel rectifier. Based on the proposed control strategy, the input power factor is close to unity and line currents are controlled to be balanced and sinusoidal. Simulation results are provided to verify the effectiveness of the proposed control strategy.