An improved zero-voltage and zero-current-switching PWM full-bridge DC-DC converter

An improved isolated zero-voltage and zero-current switching full-bridge pulse width modulation (ZVZCS-FB-PWM) DC-DC converter having dual voltage outputs of 42 V and 5 V are presented. The leading leg achieves zero voltage switching, and the lagging leg with a series diode and active snubber circuit achieves zero current switching. A phase-shifted (PS) PWM technique is used to obtain ZVZCS by equalizing the small dead times. Also, PS-PWM strategy with a robust average current-mode control can regulate the output voltage to obtain stability and reliability. Furthermore, the active snubber circuit is replaced with a flyback converter operated in the ZVS discontinuous conduction mode due to the ringing voltage of the fast recovery diodes in the secondary side. The steady-state analysis of the topology is illustrated. In this paper, simulated and experimental results are shown to verify the validity of the proposed concept. Moreover, this configuration and results in lower conduction losses in the primary side are well suited for applications above a few kilowatts.