Implementation of an interleaved three-level PWM converter with ZVS/ZCS functions

An interleaved pulse-width modulation (PWM) converter is presented to achieve the functions of zero voltage switching (ZVS) for all power switches and zero current switching (ZCS) for all rectifier diodes. Three-level hybrid DC converter is adopted to reduce the voltage stress of power switched at half the DC bus voltage and automatically balance the two input capacitor voltages. Therefore, MOSFETs with 600V voltage stress can be used at the second stage DC/DC converter after the three-phase power factor correction (PFC) circuit. The fixed frequency PWM is used in three-level PWM resonant converter to regulate output voltage. Since the selected switching frequency is less than the series resonant frequency, MOSFETs can be turned on at ZVS and rectifier diodes can be turned off at ZCS. Thus, the switching losses of power switches are reduced and the reverse recovery losses of rectifier diodes are eliminated. Furthermore, the high switching frequency at the light load in the conventional series resonant converter is overcome. Interleaved PWM scheme is adopted to share load current and further cancel current ripple at output capacitor side. Thus, output capacitance can be reduced. Finally, experiments are provided to verify the effectiveness of the proposed converter.