Research On The Optimization Control Method Of Dual Bridge Series Resonant DC-DC Converter Based On Multi Phase Shift Control Method

With the rapid development of China’s high-speed railways,lightweight and high power density have become the main development tendency and key technology of the high-speed train electric traction transmission system.With its advantages of high power density,energy saving and lightweight,the power electronic transformer(PET)has become the core equipment of next generation high-speed trains.Therefore,this paper focuses on the intermediate module dual bridge series resonant converter(DBSRC)of the PET application and studies its optimal control methods.Firstly,this paper introduces the existing researches about the DBSRC,and analyzes the operation principle and mode of DBSRC under various phase shift control methods.Based on the analysis of the phase shift control methods,the triple phase shift(TPS)control is chosen in this paper for its highest degree of control freedom and the most optimization space,which is also capable of unifying various phase shift control methods.Through the fundamental harmonic analysis modeling method,the mathematical models of the transmission power,voltage ratio and resonant current of the converter can be obtained,which set the foundation for the following optimal control method.Secondly,the steady state performance of the converter is analyzed and optimized in this paper.The resonant parameters are optimized based on the DBSRC mathematical model under TPS control method,which can effectively reduce the converter current stress at steady state.This paper also proposes a current stress optimization control method.Through this method,the converter can realize the minimum current stress operation,which can effectively reduce the resonant current stress and improve the service life and working efficiency of the converter.In addition,the proposed steady state optimal control method can also improve the soft switching range of the converter under low power operating conditions.Based on the PSIM software,a steady state simulation model is established to verify the effectiveness of the proposed steady state optimization control method.Thirdly,the dynamic performance of the converter is analyzed and optimized in this paper.A model predictive power control method is proposed.The proposed method has circuit parameter compensation capability,which can not only effectively improve the dynamic response of the converter,but also avoid the steady state error introduced by the traditional model predictive control method.Based on this,a multi-objective optimal control method is proposed by combining the proposed steady state and dynamic optimal control methods,which can effectively improve the dynamic performance of the converter while maintaining the steady state performance optimization.The proposed method is also insensitive to the circuit parameters mismatch and has good robustness.The transfer function model of the proposed control method is established,and the closed-loop stability of the method is analyzed and verified.Based on the PSIM software,a dynamic simulation model is established to verify the effectiveness of the proposed multi-objective optimal control method.Finally,a scale down experimental prototype based on Si C MOSFET is designed and built,which is mainly consisted of power and control circuits.Based on the experimental prototype,an experimental comparison between the proposed multi-objective optimal control method and the conventional control method is carried out to verify the effectiveness of the proposed control method.The experimental results indicate that the proposed control method can effectively improve the steady state and dynamic performance of the converter with good robustness,which further verifies the correctness of the theoretical analysis.