Simplified loss analysis and comparison of full-bridge, full-range-ZVS DC-DC converters

The loss of zero-voltage-switching (ZVS) of active switches has been a serious limitation of full-bridge (FBZVS) converters. Many techniques have been proposed in the past to extend the range of ZVS operation over the wider and also the full range of operation. However, in these techniques ZVS is achieved at the expense of additional conduction loss in active switches and losses in the auxiliary components. In this paper, the analysis for the additional losses in various full-range FBZVS DC-DC converters and their comparative evaluation is reported. Closed form expressions are derived for average value of device currents and losses. The loss curves for various topologies are plotted and compared. The analytical results are found to be consistent with the experimental efficiency tests performed on 500 W, 100 kHz prototype. It is concluded that a recently proposed new topology has the least penalty of additional losses.