Research And Design Of Electric Vehicle Charging Power Supply

Battery energy is the driving force of the electric vehicle which is recognized as a green transport in the twenty-first century. however, charge the battery for a long time is a major bottleneck in the development of electric vehicles, therefore, the study of efficient and fast charging technology for electric vehicles to overcome the power battery problem of long charging time, has become an important direction of the electric car research, the main contents of this paper is to study electric vehicle fast charging power supply.Charging of the battery power, the conventional methods currently used are mainly constant current, constant voltage limiting, these methods do not fit well with the charging power characteristics of the battery itself, resulting in low charging efficiency, long charging time,therefore it has important implications to study the battery charging characteristics.This paper will analysis and research the theoretical basis of fast charge, battery polarization phenomena, on the basis the paper deciding to use variable pulse charging scheme. For the following design of electric vehicle fast charging power supply, provide reference and basis for charging waveform.A good charging main circuit is the basis of fast charging. In this paper, first analysis and discuss the choice of topological structure, in order to overcome the shortcomings of hard switching circuit, the circuit uses soft switching technology. For the indicator of Qichedongzhan charging power supply of Changsha City transit system,determine the selection of the switching device.Then, analysis operating mode of ZVZCS full bridge converter, complete the parameters design, and use MATLAB (Simulink) software simulation to verify the reasonableness of device parameters calculation.This paper,on the basis of buck converter equivalent model, by calculating ZVZCS full bridge converter transformer secondary side of the effective duty, establish small signal model of ZVZCS full bridge soft switching converter. And for pulse charging process, due to the presence of non-linear inductance and capacitance element, pulse pause dynamic response is not satisfactory and so on, design electric vehicle charging control system based on fuzzy PID control and make transfer function of the main circuit of charging as the controlled object, then do simulation. Simulation results show that:with respect to the classic PID control, fuzzy PID control algorithm can adapt to the requirements of the charging system.On the basis of the above analysis and research, we completed hardware design of the charging system control circuit with MSP430F149 as the core, including the design of the smallest system, a current sampling circuit, a voltage sampling circuit, the temperature sampling circuit, phase-shift PWM and IGBT driver circuit, protection circuit, display circuit and power supply circuit and so on.In addition,design the software program of the charging control system, and give the main program design flow chart.