Bridgeless Filterless Neutral-Point-Clamped Resonant AC/DC Converter

In this article, we present a bridgeless filterless neutral-point-clamped (NPC) resonant ac/dc converter. By using the push-pull transformer itself, with the primary-side switching modulation fixed at 0.5, the proposed ac/dc converter accomplishes theoretically zero input-current ripple and so does not need the extra input filter. Semibridgeless configuration reduces the conduction loss associated with an input full-bridge diode rectifier. The resonant NPC structure much reduces the voltage stress at turn-off instant; this aspect reduces the turn-off loss occurred at the secondary-side switches. Therefore, the proposed converter features low cost, high power density, and high efficiency. A prototype with 1-kW output power is implemented to verify the superior properties of the proposed ac/dc converter.