The Study Of Electric Vehicle Charging System With The Function Of V2G

Recently,a kind of technology called V2 G has witnessed a rapid development.The technology can make the electric car's energy realize the bidirectional interaction and exchange under a controlled state.Which makes the electric cars can not only as the group of users and power consumption,but also can be regarded as green mobile energy storage unit which can provide power for the grid in the idle state.The effective control strategy can obviously improve the energy use efficiency of car-net electrical energy interaction system.So the control method of the system has also become the focus of many experts and scholars study.Accordingly,the electric car charging system with V2 G function has been researched in this paper.At first,We raised the Two-way charge and discharge circuit topology and sketched the working principle of the system.The three-phase PWM inverter(VSR)and bi-directional DC/DC converter of the system has been studies.The former is mainly on its working principle,mathematical model and the instantaneous power calculation method.The latter illustrated operating condition that electric Vehicles charge and discharge.Secondly,We choosed the the direct voltage current double closed loop control system which can stabilize the DC bus voltage and realize fast current track.In order to improve the system's power conversion efficiency,the online tested voltage and current phase difference under the state of charge(discharge)need to close to 0degrees(180)quickly.The paper started with improving the system's DC bus voltage utilization and adopted the space voltage vector SVPWM modulation method.We designed the control flow chart of the system when charge and discharge,then choosed the charge and discharge pattern according to the electric car battery's SOC and make sure the battery in the permitted range of charging and discharging.At last,established a system simulation model,By comparing the direct voltage current double closed loop control method with the online tested output voltage and current waveform which has studied based on the control strategy in this paper.Verified the control strategy which we proposed in this paper can improve the system energy conversion efficiency.