Research On Full Bridge Three-level LLC Resonant Converter In Charger Pile

The use of electric vehicles with zero emissions,low pollution,high rate of energy has been receiving extensive attention,with the development of electric vehicle industry,electric vehicle charging technology has become a hot research topic in today's society.Among them,the research and development of charging pile is of great significance.This paper mainly studies DC / DC converters in non-vehicle DC charger pile,and uses full bridge three-level LLC resonant converter topology.Detail research work is as follows: First of all,This paper analyzes the working principle and the DC gain curve of the full bridge three-level LLC resonant converter,and designs the parameters of each component in the main circuit.Second,a small signal model of LLC resonant converter is established by the extended describing function method.This paper studies the voltage loop and current loop double closed loop control strategy,designing of PI controller based on engineering setting method.Third,in order to improve the dynamic performance and steady-state performance of the system,the fuzzy self tuning PI controller is designed in the current loop.When the voltage and current are in different stages,the ratio of the difference is amplified,mproving the accuracy of voltage and current sampling.In this paper,the resonance of multiple voltage levels is proposed,the switching frequency of the system at low voltage output is still at the ideal resonant frequency,improving the efficiency of low voltage output.Fourth,this paper uses MATLAB software to build the simulation model,and detailed analysis of the working process of the components of the circuit,the simulation results of traditional PI controller and fuzzy self-tuning PI controller are compared and analyzed in this paper.Fifth,this paper designs the hardware circuit and the software flow of the system in detail,and writes the software code.The experimental prototype is designed,and the experimental data are analyzed in detail.By analyzing the simulation waveforms and experimental data,It is proved that the designed fuzzy control method has good dynamic performance and steady state performance.By changing the transformer,resonant converter is obtained multiple voltage levels,and the converter hashigh efficiency in the low-voltage output,the experimental results verify the correctness of the control strategy in this paper.