Research On Multimodule Parallel Current Sharing Technology In Phase-Shifted Full Bridge Converter

With the development of new energy vehicles,data communications,aerospace and other technologies,the demand for high-power DC/DC power supply capacity is increasing.Due to lack of redundancy and flexibility,the single-module DC large power supply can no longer be applied to very large power Application.Therefore,the research and design of multi-modular DC/DC power supply suitable for large-capacity systems is an important direction.This thesis studies the topology of the modular DC/DC power converter and its control method,and multi-module parallel current sharing technology.This thesis deeply studies the working principle and key problems of the phase-shifted full-bridge DC/DC converter.A number of topological improvement schemes are compared and an improved topological structure based on diode clamp is selected.According to the input and output indexes in the application,the component parameters is completed.This thesis analyzes the control strategy of phase-shifted full-bridge ZVS DC/DC converter.According to the different load,CCM and DCM small-signal mathematical model of phase-shifted full-bridge converter are established by using PWM switch model method.For CCM mode,double closed-loop PI parameters are designed.For DCM mode,single-voltage loop PI parameters.At the same time,in order to solve the contradiction between the high power switching frequency and the slow calculation speed of DSP,the exact control model of the predictive current algorithm in full-bridge converter is deduced and the simulation results show that it is effective.For parallel current sharing for multiple DC/DC power modules,this thesis analyzes the existing working principle of common current sharing method and determine the inner current signal injection point structure as the main method.Simulation model is designed to verify the effect of its current sharing.Based on the current sharing structure of this thesis,the digitalized current sharing control method of DC parallel system is studied.The hardware and software design of DSP-based digital current sharing system was completed,and the feasibility of the principle was verified on two experimental prototypes.