Study On The Recharge And Discharge Machine Of Electric Vehicle Based On V2G

In recent years, with energy and environment problems being increasingly serious, electric vehicles gradually become a hot research topic, and have enjoyed great development. Then, those electric vehicles’ influence as high-power appliances for power grid also gradually increases. In order to use the resource in a proper way and reduce their negative effects on the grid, the V2G(Vehicle to Grid) technology arises. With this technology, the electric vehicles can not only be treated as electrical appliances, but also be used as distributed power supply, and thus can conduct reasonable electricity conversion with grid to maintain grid stability, using the information of the smart grid. Therefore, as a key part of the V2 G technology, the recharge and discharge machine which can realize two-way power flow has become a hot research topic.In the first chapter, an analysis of the advantages and disadvantages of all kinds of topology structure of V2 G recharge and discharge machine is made and the two-level topology is chosen as the final simulation circuit topology —— voltage three-phase half-bridge topology is used to the front bidirectional AC/DC converter and the nonisolated bidirectional Buck-Boost DC converter is used to the back bidirectional DC/DC converter. The mathematical model of the front and back bidirectional AC/DC and DC/DC converters is deduced. By choosing the right V2 G recharge and discharge machine performance parameters, the parameters of the main circuit like L and C are analyzed and designed.In the second chapter, the control strategy and the control principle based on dq rotating coordinate system of bidirectional AC/DC converter are focused on, and PI of Current inner loop and voltage loop is designed. SVPWM modulation algorithm is expounded in detail and modeling simulation. The PLL are analyzed and PLL is affected when three-phase voltage unbalanced or distorted. Based on this, a kind of none-PLL SVPWM control is put forward with given phase Angle and the control strategy is advanced to eliminate the influence of frequency fluctuations of the grid voltage, with increasing the frequency compensation of phase. At the same time, the control strategy and control principle of bidirectional DC/DC converter are focused on, with average current control of charging mode and direct voltage control of discharging mode. And parameters of the control system is design, with the stability of the control system analyzed, and simulation of the control system is verified.In the final chapter, the overall model of V2 G recharge and discharge machine is set up and a variety of charging and discharging model are verified in MATLAB/Simulink. Based on this, the recharge and discharge machine based on V2 G that is able to eliminate the grid harmonic is set up, and the feasibility of the recharge and discharge machine based on V2 G is verified through the Simulation.