Electric Vehicle CLLC Type Two-way DC-DC Change Study Of The Changer

With the goal of carbon peaking and carbon neutrality in my country,the development speed of electric vehicles has been improved,and bidirectional DCDC converters with functions such as voltage conversion,bidirectional energy transmission and electrical isolation are an important part of electric vehicles..Various types of bidirectional DC-DC converters have been used in electric vehicles.This paper mainly analyzes the topology of three bidirectional DC-DC converters,and designs the parameter optimization method and control strategy of the CLLC resonant bidirectional DC-DC converter.1.According to the requirements of new energy electric vehicles for converters,the commonly used bidirectional DC-DC converter topology is analyzed,and the CLLC resonant bidirectional DC-DC converter is selected as the research object of this paper to study the converter topology.Analyze work patterns.Through simulation,it is verified that the output voltage error of the CLLC resonant bidirectional DC-DC converter selected in this paper is small.2.The equivalent mathematical model of the CLLC resonant bidirectional DC-DC converter is established by the fundamental wave equivalent analysis method,and the functional relationship between the voltage gain of the transformer,the parameters of the resonant tank and the switching frequency is obtained,and then the voltage gain,Power transfer characteristics and the effect of switching dead time on transfer power.3.According to the relationship between the voltage gain of the transformer and the parameters of the resonance circuit,the optimization method of the parameters of the resonance circuit is designed.Then,according to the requirement of constant voltage gain in practical application,the design methods of excitation inductance,resonant inductance and resonant capacitor are given respectively.The transformer and resonant inductor losses of the converter are also analyzed.4.Aiming at the problem that the integral link in the traditional PI control may lead to excessive overshoot of the output voltage waveform,a composite control strategy combining single phase shift control and integral separation is designed.Firstly,the structure of single phase-shift closed-loop control is studied,including PI control and pulse width modulation technology,and the PI control is analyzed in detail,and the shortcomings of the integral link are pointed out,and then the integral separation control is introduced to solve the overshoot of the output voltage waveform caused by the integral link.The problem.The effectiveness of the composite control combined with single-phase-shift transformation control and integral separation is verified by simulation.