A new current-fed full-bridge converter for high step-up gain and high efficiency

Till now, the various types of current-fed-type converters have been developed, and they exhibit good performance in high power step-up applications. However, they have a common serious problem caused by the leakage inductor of a transformer. Therefore, they require an RCD snubber to prevent high voltage spikes across the turn-off switches, which causes the deterioration of overall efficiency. To relieve these limitations, a new current-fed full-bridge (CFFB) converter, which is integrated with a two-switch forward (TSF) converter, is proposed for high step-up gain and high efficiency in this paper. In the proposed converter, the integrated TSF converter can not only absorb the voltage surges across the turn-off switches without an additional loss, but also help the proposed converter to obtain high step-up gain. Therefore, the proposed converter can be promising for the isolated high power step-up applications. To confirm the operation, validity, and the features of the proposed circuit, experimental results from a 960W, 48-480 V_dc prototype are presented.