Research On Two Phase Interleaved Parallel LLC-LC Resonant Converter Based On Switched Capacitor

At present,the new energy vehicle industry is developing rapidly.In order to adapt to the wide range of battery terminal voltage changes during charging of new energy vehicles,it is of great significance to study a DC/DC converter with wide gain and high efficiency.First,after understanding the research status of wide gain resonant converter at home and abroad,LLC-LC resonant converter is selected as the research object.In order to solve the problem of large output current ripple of single-phase LLC-LC resonant converter,multiphase interleaved parallel technique is adopted.However,in a multiphase parallel system,the inevitable deviation of the resonant element challenges the current-sharing characteristics of the converter,so a Switch-Controlled Capacitor(SCC)current-sharing circuit is introduced to achieve current-sharing between the system modules.Secondly,the working principle of two phase staggered parallel LLC-LC resonant converter is introduced.The AC equivalent model is established by using the fundamental wave analysis method,the gain expression of the converter is derived,and the resonant network parameters are optimized.At the same time,the working region is divided and the optimal operating region of the converter is determined.Furthermore,the current sharing characteristics of the two phase staggered parallel LLC-LC resonant converter are analyzed in detail,and the mathematical model of the converter current sharing is established.In order to solve the problem of current sharing in the converter,a SCC current sharing circuit is introduced,and the capacitor design process of SCC current sharing circuit in the two-phase staggered parallel SCC-LLC-LC resonant converter is given by using the mathematical model of current sharing.Then the current sharing control strategy of the converter is designed by using the net charge meter of the periodic input of the resonant cavity to measure the output current of each phase.Realize the current sharing of two phase staggered parallel system.Then,according to the performance indicators of the converter,the resonant network parameters and magnetic components are reasonably designed,and the power device selection is completed.TMS320F28335 is selected as the main control chip,completing the converter control circuit design and software design.Finally,a preliminary theoretical verification of the two-phase interleaved parallel SCC-LLC-LC resonant converter was conducted using PLECS simulation software,and a3.3k W experimental prototype was built for practical verification.The experimental results verify the correctness of the established current sharing mathematical model and the feasibility of the designed current sharing control scheme.