New series half-bridge converters with the balance input split capacitor voltages

Abstract

A new DC/DC converter is presented for high input voltage and high load current applications. In order to reduce the converter size and achieve high circuit efficiency, MOSFETs with high switching frequency are adopted in the converter. To achieve high circuit efficiency, two half-bridge converters are connected in series to reduce the voltage rating of power switches and asymmetric pulse-width modulation is adopted to control output voltage and achieve zero voltage switching turn-on for all power switches. In order to share the load current and reduce the current rating of rectifier diodes for high output current applications, two center-tapped rectifiers are connected in parallel. The series-connected transformers at high voltage side are used to balance two output inductor currents. Two series capacitors are connected at the AC terminals of two half-bridge converters to balance two input capacitor voltages in every switching cycle. The output capacitances of MOSFETs and the resonant inductances are resonant at the transition instant such that MOSFETs can be turned on at zero voltage switching. Finally, experiments based on a laboratory prototype with 1kW rated power are provided to verify the effectiveness of proposed converter.