Study On Electric Vehicle Charging And Discharging System Of The AC Micro Grid

In recent years,with the rapid development of auto industry,the use of the automobile has increased dramatically.And the global consumption of fossil fuel and emissions of automobile exhaust are increased.What's more,the global energy crisis and environmental pollution are accelerated.To solve the problems,the electric car has been proposed to replace the automobile.However,due to the distribution characteristics and movement characteristics of electric vehicles,higher charge and discharge voltage is needed,the management of the electric vehicle charging and discharging system is necessary,and it has great significance for improving the utilization of renewable energy.Harmonic wave will be brought to the vehicle charging and discharging system for the using of the power electronics device.The sine wave will be distorted and quality of electric energy will be decreased for it.In order to reduce the influence of harmonic to electric vehicles,the three-phase voltage source PWM converter and bi-directional buck/boost converter topology have been studied,and its application in micro power grid mathematical model of electric vehicle charging and discharging system has been built in this paper.On the bases of traditional control strategy,the SVPWM control and fuzzy PI control are introduced,and it can be used to make the two-way flow of energy between power grid and electric vehicles,improve the power factor of the system,and increase the stability of the system.What's more,harmonics can be effectively suppressed by the LCL filter,and it is joined in front of the three-phase voltage type AC/DC converter.The LCL filter is also used between the two-way buck/boost converter and the battery,and the DC voltage produced by AC/DC converter is increased,the charging current ripple of the battery is reduced.Matlab/Simulink simulation model is established based on the proposed charge and discharge control system to verify the effectiveness of the charge and discharge control system.The comparison of simulation results and computation result have been shown that system simulation result is consistent with the expected effect,system harmonic is reduced,the power factor is improved,the battery charging voltage is increased,and energy bi-directional flow is achieved by using the charge and discharge control system.Finally,the system hardware circuit is built and the experiment of the system based on the research is shown that the reality of the system is good,fast charging can be realized,and the response speed of the system is increased.