A step-down isolated three-phase IGBT boost PFC rectifier using a novel control algorithm with a novel start-up method

For some industrial converter applications such as battery chargers, a DC/DC converter is needed to step down the high DC (direct current) voltages generated by PWM (pulse with modulated) rectifiers to lower voltage levels such as 110V/220V. These both complicate the design and decrease the efficiency. In this paper, a novel topology that includes a step-down transformer and a novel control algorithm is proposed. The proposed current, which is synchronized, look-up table based, sinusoidal PWM control method (CS-LUT-SPWM method) using switching frequency-oriented synchronization (SWFOS) results in a very fast PWM generation and stable operation. Finally, a new thyristor-based start-up circuit providing safe operation when there is energy black out is proposed. A 32-kW converter has been designed, built, and tested to prove the concepts. The proposed converter has an efficiency higher than 94%, an input current total harmonic distortion (THDi) less than 5%, and a power factor closer to 0.99. Theoretical calculations and experimented results show that proposed converter has better efficiency (94%-96%) compared to classical PWM boost rectifiers with a series DC/DC converter topology (92%) in the literature. Fast PWM control algorithm, less complexity, low switching noises, one-stage conversion circuit, and novel start-up circuit are other advantages of the proposed converter.