A multilevel-voltage source rectifier with a three-phase diode bridge circuit as a main power circuit

A novel system obtaining very low distorted waveforms of input AC currents of three-phase rectifier circuits is proposed. This rectifier system consists of a three-phase diode bridge circuit as a main power circuit, AC reactors, and an additional circuit which serves as an active filter with low switching frequencies and a forced commutation circuit for the diodes. The authors describe the operation principle, analysis of the waveforms of input voltage and current, multiple phase-shifted systems, and experimental results. The proposed system gives excellent input current waveforms and has many advantages over conventional systems