Research And Design Of Efficiency Optimization Strategy For Multiphase Interleaved Parallel DC-DC Converter

The interleaved parallel technology not only improves the power level of the power converter system,but also reduces the voltage ripple and current ripple of the converter system and significantly improves the power density of the power converter system.This thesis takes the widely used two-phase interleaved parallel synchronous rectification BUCK DC-DC converter as the research object,and analyzes the mathematical model,control strategy,efficiency model and efficiency optimization strategy of the system.The main research contents are as follows:First,the theoretical study of the working mode of the two-phase interleaved parallel synchronous rectification BUCK converter is carried out to lay a theoretical foundation for the design of subsequent control strategies.Secondly,the control strategies of power converters with interleaved parallel topology are studied.Based on the traditional voltage and current double closed-loop PI control strategy,combined with the model predictive control strategy,an improved PI-model predictive control strategy is proposed to improve the dynamic response performance of the system.The simulation experiment completed the realization and performance comparison of the two control strategies.Thirdly,the loss of the single-phase converter is analyzed,and a method for establishing a multi-dimensional variable efficiency prediction model based on the support vector regression is proposed.Besides,the efficiency characteristic of the converter is obtained by curve fitting,and the differential evolution algorithm is used to obtain the current load distribution plan when the overall efficiency of the system is optimal.On this basis,an efficiency optimization control strategy is designed,and the overall efficiencies of the system under the current sharing method and efficiency optimization method are compared through simulation experiments,which verifies the rationality of the efficiency optimization control strategy.Finally,an experimental platform has been built based on the completion of the hardware and software design.The excellent steady-state performance of the dual-loop PI control strategy and the superior dynamic performance of the PI-model predictive control are verified through experimental tests.The overall efficiency of the traditional current sharing control strategy and the efficiency optimization control strategy are compared,and the experimental results show the correctness of the efficiency optimization strategy.