Onboard Bidirectional Converter For The Lithium-ion Batteries

With the development of national smart grid and rapid application of electric vehicles, now it is necessary to propose and carry out further research on the technology of energy interaction between electric vehicle and grid(V2G). Meanwhile, the birdirectional converters are essential to transfer electrical energy between electric vhilces and the grid.Firstly, In this thesis, the study status for bidirectional converters between vehicle and grid are reviewed, whose circuit topologies and characteristics are analyzed. The circuit topology of the bidirectional converter is based on two-level bidirectional converter, consisting of a single phase voltage source PWM rectifier and an isolated bidirectional full-bridged DC-DC converter.Secondly, the topology, the operational principle, and the control strategy of the single phase voltage source PWM rectifier are analyzed to design parameters of the main circuit topolgy. It is carried out on Matlab/Simulink According to the simulation results, we analyze the dynamic performance and power factor of the proposed PWM rectifier, which validates our control strategies and parameter design.Thirdly, the thesis analyzes the circuit topology, operational principle, and control strategy of of the presented isolated bidirectional full-bridged DC-DC converter, which is built on Matlab/Simulink. Furthermore, in the buck mode, either the output current or the output voltage can be controlled. In the boost mode, the DC-link voltage can be kept stable.Finally, with the parameters of lithium-ion batteries, Thevenin equivalent circuit model is used to build a complete simulation model including the PWM rectifier and the full brige DC-DC. the thesis develops own control strategies to charge the batteries from the grid engery and regenerates the battery energy to the grid. Results show that the constant current charge and the constant voltage charge modes can be easily carried out for the battery charging. At the same time, the constant current discharge mode is also conducted to inverter from dc to ac with the sine current and unit power factor...