Research And Design Of On-board Charger For New Energy Electric Vehicle Based On GaN HEMT Device

In recent years,with the continuous growth of the new energy electric vehicle industry,high performance on-board chargers have become a research focus of the current new generation of charging technology due to their flexibility and convenience.In single phase household on-board charging equipment,the grid side power factor,overall efficiency,and power density are key issues that need to be solved urgently.Therefore,in view of the above problems,this paper determines the on-board charger system architecture of new energy electric vehicle and studies the on-board charging circuit of new energy electric vehicles based on duty cycle predictive control strategy and GaN HEMT device.This research is of great significance for the promotion and application of new energy electric vehicle.The main research work of this paper is carried out from the following aspects:(1)Research on the system architecture of single-phase home on-board charging equipment.Based on the study of the existing scheme and main technology of the on-board charger,the advantages and disadvantages of the traditional charging equipment are analyzed and compared,and a kind of on-board charger scheme with interleaved APFC-Boost converter as the front AC/DC part,half bridge LLC resonant converter as the back DC/DC part and DCM flyback converter as the auxiliary power supply of the system is determined.(2)Research on interleaved parallel APFC-Boost conversion circuit based on duty cycle predictive control.This paper designs the main circuit of the front interleaved APFC-Boost converter,analyzes its working principle,and gives a practical design method of the main circuit,including EMI filter protection circuit,single-phase rectifier bridge,Boost inductor,power devices,input and output capacitors,etc.A duty cycle predictive control algorithm is studied.The algorithm has the advantages of small amount of calculation,fast response and can give full play to the advantages of digital control.The circuit model of the converter was built by using Matlab/Simulink simulation software,which demonstrated the correctness of the algorithm and parameter design.(3)Research on half-bridge LLC resonant converter circuit based on GaN HEMT device.This paper analyzes the working principle and mode of the rear half bridge LLC resonant converter,uses the fundamental wave analysis method FHA to establish an equivalent circuit model,and calculates the voltage gain function,the impedance characteristic expression and theoretical research.This paper studies the structure,working principle and performance characteristics of GaN HEMT devices,and develops the design and optimization of dedicated drive circuits from the aspects of drive resistance,Miller platform,parasitic effects and signal delay,and a variable frequency constant duty cycle algorithm controller was designed based on the loop stability.Finally,the parameters of the resonant network and high frequency transformer are designed.In addition,also analyzes and designs introduces the circuit topology and working mode of auxiliary power DCM flyback converter in the system.Two output voltages of 15V and 5V are used to supply power to each module of the system.(4)Experimental study on the principle prototype of single phase household on-board vehicle charger.Finally,this paper completes the design of the 1kW prototype based on GaN HEMT,prototype uses floating DSP TMS320F28335 controller to realize full digital control.The experimental results show that all indicators of the designed on-board charger meet the requirements,and the overall efficiency of the system is high,which verifies the effectiveness and feasibility of the theoretical analysis,parameter design and control method of the system scheme.