An Improved Full-Bridge Converter with a Five-Diode Rectifier for High Efficiency in Wide Voltage Range

This article presents an improved full-bridge converter with a five-diode rectifier. The primary side circuit is composed of a full bridge with two transformers and two split capacitors. On the secondary side, five diodes are employed in the rectifier stage. By using the asymmetrical pulse width modulation (PWM) signals, this converter can realize the zero-voltage switching (ZVS) of all switches and reduce the circulating current. The two transformers share the load power equally in whole load range. Compared with the other dual transformer isolated full-bridge converters, the transformers in the proposed converter are easy to optimize because of the load power equal sharing. Furthermore, the output filter inductance is reduced, which reduces the loss and volume. According to the loss analysis, the proposed converter has higher efficiency compared with some other dc-dc converters. The experimental results of a prototype with 300-400 V input voltage and 250 V/4 A output verify the performance of the proposed converter.