Efficiency Improvement of an Adaptive-Energy-Storage Full-Bridge Converter by Modifying Turns Ratio of a Coupled Inductor

This letter proposes a simple and practical way to improve the efficiency of an adaptive-energy-storage (AES) full bridge converter. Since the turns ratio of coupled inductor is 1 in the conventional AES converter, the leading-leg and lagging-leg have the same peak current. By modifying turns ratio of coupled inductor, part of leading-leg current can be steered to the lagging-leg; thus, the peak current of lagging-leg is higher than that of leading-leg and a wider range of zero-voltage switching (ZVS) operation is obtained. In the improved AES converter with modified turns ratio, the energy from primary side can be transferred to the secondary side during freewheeling interval. Both the current ripple of filter inductor and the voltage stress of rectifier diode are reduced. Compared with the conventional AES converter, the improved converter can obtain a wider ZVS range, lower current ripple, and higher conversion efficiency. The detailed theory analysis and experimental results are presented in this letter.