Research Of Electric Vehicle Charging And Discharging Device

The market and social value of electric vehicles could not be underestimated.To expand the promotion of electric vehicles, the first problem should be solved are battery technology and infrastructure needed to recharge the cars. This paper focuses on the latter part.There is many problems using the traditional method in electric vehicle charging and discharging systems. Such as harmonic pollution,low power factor and long charging time. Based on the analysis of battery’s characteristics used in the electric vehicle,SVPWM control and fuzzy PID control is introduced in this paper, to realize bidirectional flow of energy while achieve units power factor, improve stability and dynamic characteristics of the entire system. On the other hand,further improve the charge-discharge rate without affecting the battery life.In this paper, the whole system is divided into two parts:grid-side part and EDV-side part.The main circuit of grid side part adopts three-phasevoltage type PWM converter by SVPWM to control the realization of grid side current sinusoidal, high power factor and low harmonic pollution converter, and the energy can be two-way flow between the power grid and electric vehicle.Double-loop control method which introduced current feedback and voltage feedback is used in controlling the grid side converter.we also introduce fuzzy PI control,soft switchand voltage feed forward control into the double closed loop, to improve the system dynamic performance, and also to maintain the best state in the complicated situation.The EDV-side pat use a bi-directional DC-DC converter controlled by PWM, enabling the switching charge and discharge modes. By controlling the PWM pulse width, the charging and discharging voltage can be controlled on a specified value.In order to verify the validity of the charge and discharge system and the control strategy, simulation experiment is carried out on the platform of matlab/simulink and experiment carried on the hardware.the results show that the system can effectively realize the charging and discharging function, have a good performance in the dynamic response small harmonic pollution.