A hybrid resonant ZVZCS PWM full-bridge converter for MVDC grids

A novel hybrid resonant zero-voltage zero-current switching PWM full-bridge converter with capacitive output filter is proposed in this paper. The hybrid resonant converter, with two full-bridge cells sharing a bridge leg and connecting the secondary windings of two transformers in series, operates in discontinuous current mode and can achieve zero-current switching for main power switches and rectifier diodes over the whole load range. Meanwhile, the auxiliary switches with small current rating can realize zero-voltage switching naturally. Hence, the switching loss is reduced, which is vital in MVDC applications. The influence of the turns ratio of auxiliary transformer and the resonant capacitance on the peak and turn-off currents is discussed in detail. The performance of the converter is validated by simulation and experimental results.