A Research Of Bidirectional Power Converter For Electric Vehicle

In recent years,electric vehicles have become a new favorite in the automobile industry due to their advantages of low emission,energy saving and environmental protection.With the rapid development of electric vehicles,their corresponding charging and discharging technologies are also changing with each passing day.Charging and discharging technologies are related to the effective use of electric energy,so advanced charging and discharging technologies have become the core content of electric vehicle research.Generally,the on-board power battery charger and low-voltage battery charger of electric vehicles are designed as separate devices,which wastes on-board space and pushes up the cost of the vehicle.At the same time,most power battery chargers do not support two-way energy flow and V2G(Vehicle to Grid)function,so they cannot provide users with better experience.So this thesis will be of electric cars on-board power battery charger technology at home and abroad on the basis of the reuse design of the power circuit topology,the separation of the original low battery charger and car charger for reuse to merge,and can be improved so as to realize the power battery to the power grid feedback power electric cars,two-way power converter.This bi-directional power converter can achieve the purpose of optimizing volume,reducing weight and saving cost,and provide additional V2 G function to improve the user experience.This thesis first of all,based on the bidirectional power converter is more complex scenarios and technical requirements,choose the single phase full bridge AC/DC two-way power converter topology as the first level of structure,choose three port isolation full bridge DC/DC converter as the secondary structure of bidirectional power converter,the structure of two levels of complement each other in function,achieve the required function.Secondly,it briefly analyzes the different working modes that the bidirectional power converter can achieve in different application scenarios,and the working principle and working mode of single-phase full-bridge AC/DC part and isolated three-port DC/DC converter part respectively in different working modes.Then according to the working principle of the bidirectional power converter and combined with the system steady state circuit,a mathematic model of the bidirectional power converter two-stage structure,whichdeduces two levels of structure in different working mode of the transfer function,and according to the different work mode put forward the corresponding control algorithm,using MATLAB/Simulink software verify the correctness of the algorithm and the topological structure of the system.Finally,on the basis of theoretical analysis,a test prototype is built,and the theoretical correctness of the bidirectional power converter is verified by debugging the hardware platform.The bidirectional power converter designed in this paper can achieve three different working modes,realize the integration and reuse of charging and discharging power circuits,and improve the power density.