Single-stage soft-switched HF transformer isolated AC-to-DC multiphase converter

A single-stage soft-switched high-frequency (HF) transformer isolated AC-to-DC multiphase converter is proposed. The operation and analysis of the proposed converter is presented for different operating modes. Using harmonic analysis, it is shown that N = 3 is almost the optimum number of cells to reduce the input current HF harmonic components. A design example of a 5 kW, 420 V, 50 kHz AC-to-DC multiphase converter is presented to illustrate the design procedure. PSPICE simulation results are presented to verify the operation and performance of the designed converter. A 110 V RMS, 1.5 kW, 50 kHz laboratory prototype was built using fast IGBTs to verify the operation and performance of the proposed 3-cell single-stage AC-to-DC multiphase converter. The PSPICE simulation and experimental results show that all the switches are soft-switched. Because of the HF transformer isolation, the intercell cross-conduction problem is eliminated