Current Stress Optimization Of Dual Active Bridge Converter Based On Extended Phase Shift Control

With the aggravation of energy crisis and the improvement of environmental protection awareness,renewable energy power generation technology is developing rapidly.Among them,Dual Active Bridge(DAB)converter is widely used in DC microgrid and energy storage due to its small size and easy to realize soft switching.In order to reduce the current stress of double active bridge converter(DAB)based on extended phase-shift control in soft switching,a current stress optimization strategy applied to All-ZVS mode and adaptive soft switching mode is proposed.Based on the loss model of DAB converter,the optimal current stress and efficiency under different soft switching modes are compared and analyzed.The specific research contents are as follows:Firstly,the working principle of DAB converter is analyzed in detail,and through comparison,it is found that when the input and output voltages do not match,the extended phase-shift control can obtain better current stress optimization effect through a relatively simple control method,and the converter efficiency is higher.Secondly,in order to reduce the current stress of DAB converter in soft switching,a current stress optimization strategy suitable for All-ZVS mode and adaptive soft switching mode is proposed.According to the transmission power,the optimization objective is transformed into a single variable function,and the optimal value curve is obtained by calculating the extreme value.Combined with the characteristics of transmission power region and current stress relationship of different soft switching modes,the optimal combination of phase shift ratio is found in the feasible region to minimize the current stress.Finally,based on the loss model of DAB converter,the influence of optimized current stress of two soft switching modes on converter efficiency is analyzed.An experimental platform based on GaN-HEMT was built for verification.The experimental results show that:1)The proposed optimization strategy can minimize the current stress in soft switching mode and improve the efficiency of the converter;2)Compared with the All-ZVS mode,the adaptive soft-switching mode reduces the overall current stress by 37.5%,and improves the overall efficiency of the converter by 11.6%.