Zero-voltage-switched, three-phase pulse-width-modulating switching rectifier with power factor correction

A three-phase, zero-voltage-switched, pulse-width-modulated, a.c.-to-d.c.-converter, comprising in combination:

• a transformer having a primary winding and a secondary winding;
• means including rectifying means and filter means for coupling said secondary winding to a load;
• a three-phase input, comprising a first-phase input, a second-phase input, and a third-phase input;
• switching bridge means for coupling said three-phase input means to said primary winding;
• said switching bridge means comprising a first switching means coupled between said first phase input and a first side of said primary winding, second switching means coupled between said first-phase input and a second side of said primary winding, third switching means coupled between said second-phase input and said first side of said primary winding, fourth switching means coupled between said second phase input and said second side of said primary winding, fifth switching means coupled between said third-phase input and said first side of said primary winding, and sixth switching means coupled between said third phase and said second side of said primary winding;
• resonant circuit means, including a leakage inductance of said transformer and a parasitic capacitance of said switching bridge means, said resonant circuit periodically established zero voltage across said first, second, third, fourth, fifth, and sixth switching means;
• means for generating a six-step, pulse-width-modulating signal to switch between an off-state and an on-state said first, second, third, fourth, fifth, and sixth switching means at a zero voltage established by said resonant circuit means and generate a pulse-width-modulated series of in-phase, current and voltage pulses with successive voltage pulses of said series of opposite sign;
• and
• said means for generating a six-step, pulse-width-modulating signal providing a period of zero transformer primary voltage between each successive voltage pulse of said series.