Performance Optimization Method Of Dual Active Bridge Converter Based On Multiple Voltage Matching Points

The electric vehicle charging pile with bidirectional power transmission is the key equipment in the Vehicle to Grid(V2G)technology,and the bidirectional DC-DC converter is an important part of the charging pile,and its performance is an important part of the charging pile.index.Dual active bridge(DAB)converters with DC blocking capacitors can improve performance over a wide voltage range by switching the converter between full-bridge mode and half-bridge mode.However,the current DAB converters with DC blocking capacitors work under the traditional hybrid-single-phase-shift modulation strategy,and still have the problems of narrow zero voltage switching(ZVS)range and large current stress.The performance optimization of the DAB converter is studied,and the conversion performance is improved by realizing the full load range ZVS under a wide voltage range and optimizing the global root mean square(RMS).(1)Aiming at the problem that the DAB converter with DC blocking capacitors cannot achieve a wide voltage and full load range ZVS under the traditional hybrid single-phase-shift modulation strategy,this paper proposes a new hybrid extended-phase-shift modulation strategy.The DC blocking capacitor enables the converter to switch between full-bridge mode and half-bridge mode to obtain multiple voltage matching operating points,providing more control freedom for the performance improvement of the converter.(2)Under the proposed new hybrid extended-phase-shift modulation strategy of multi-mode switching,based on the modal analysis,power transfer characteristic analysis,ZVS range characteristic analysis,and RMS current characteristic analysis of the converter,a multi-mode switching optimization method for voltage matching is proposed.The optimization method aims at extending the ZVS range and reducing the current stress.Based on the half-cycle volt-second area balance principle and the RMS current optimization method under mode switching,the optimization of ZVS and global RMS current in the full load range of the converter under a wide voltage range is realized,and the control law of the new hybrid extended-phase-shift modulation strategy is simplified.(3)An experimental prototype with rated power of 1000 W,operating frequency of 200 k Hz,input of 200 V and output of 100-400 V is designed.The new hybrid extended-phase-shift modulation strategy and its performance optimization method proposed in this paper are verified and compared with the traditional hybrid single-phase-shift modulation strategy.The experimental results show that the modulation strategy and optimization methods proposed in this paper can improve the converter performance in terms of ZVS range,global RMS current and conversion efficiency.