A General Pulse Width Modulation Method for Zero-Voltage-Switching Active-clamping Three-phase Power Converters: Edge Aligned Pulse Width Modulation (EA-PWM)

A general PWM method for soft-switching three-phase power converters-Edge Aligned PWM (EA-PWM) is proposed. It aligns all the high loss commutation instants of the converter bridges in a switching cycle at the same instant so that all the switches of the three-phase converter can realize zero-voltage-switching (ZVS) with the help of the resonant auxiliary circuit which operates once each switching cycle. EA-PWM scheme for ZVS active-clamping three-phase converter is introduced. ZVS condition and voltage stress of the converters is derived. EA-PWM can adapt to various modulation methods such as SPWM, Harmonic Injected SPWM, Continuous Pulse Width Modulation (CPWM), Discontinuous Pulse Width Modulation (DPWM), etc. The ZVS condition of three-phase Compound Active Clamping (CAC) converter are discussed. Finally, EA-PWM scheme is verified in Back-to-Back (BTB) converter prototype.