An Interleaved Three-Phase PWM Single-Stage Resonant Rectifier With High-Frequency Isolation

This article proposes a novel interleaved three-phase pulsewidth modulation (PWM) single-stage resonant ac-dc converter with high-frequency isolation. The proposed converter comes from an interleaved three-phase power factor correction (PFC) semistage and a three-phase LLC resonant dc-dc semistage. Soft-switching commutation can be achieved on the power switches in this converter including zero-voltage-switching-on on the primary side power switches and zero-current-switching-off on the secondary diodes. The LLC resonant tank in the dc-dc semistage serves as a bandpass filter that attenuates the line-frequency ripple and keeps the switching frequency component passing through the transformer. The high frequency transformer keeps in a small size. Steady-state analysis of the resonant dc-dc semistage for PWM control is proposed to analyze the dc-link voltage stress. Moreover, the dc-link capacitor value can be greatly reduced without affecting the PFC operation. A prototype that converts a wide three-phase input voltage to 300 V dc output voltage is built and tested. The experimental results present an almost unity power factor with a conversion efficiency as high as 96.3% with total harmonic distortion as low as 3.86% at a full-load condition.