Research On Bidirectional DC-DC Conveter Of Electric Vehicle

Energy crisis is threatening the life mode of production human beings are used to, atmosphere pollution exists in the every corner of human existence, endangering human health. Famous for its environmental, economic, and high-tech content, the electric car received much attention of scholars. To improve the performance of electric vehicles, bi-directional DC/DC converters were introduced into the electric vehicles. In this paper the operation condition of the loading of ultracapacitors composite power supply of the electric car demand, adopts the interleaved parallel bi-directional dc/dc converter topology, and different control strategies are studied to improve the dynamic performance of the converter.Firstly, simple introduction of the research in electric vehicle and its bidirectional DC/DC converter status at home and abroad was made. After that, the working principle of interleaved parallel bidirectional DC converters was analyzed under different working conditions, then according to the different control targets, the relative traditional dual closed loop controllers under different working conditions were designed in the cases of the small signal model that was set up, simulations showed that the controllers presented a good rresult in improving the performance of the system.Aiming at the shortcomings of the traditional double closed-loop control strategy, under the condition of the output voltage was stable, in order to further improve the dynamic response of the converter as well as to the input and output of robustness, an improved one cycle control strategy was applied to regulate the charging(Buck) model and the relative small signal model was set up, improvement of the response speed of the converter and the robustness of the input voltage were conspicuous. The discharging(Boost) model was regulated by input voltage feed-forward combine with the output voltage feedback control strategy and its small signal model was set up, the dynamic performance and robustness of the system were well improved. And then set up the simulation model under different control strategies respectively. Compared the simulation results to that of traditional one’s, the simulation results showed that under the corresponding working mode, the improved control strategies of both mode presented better control effects.The corresponding simulation models were built according to different control strategies under relative working modes respectively. Contrast and analysis of the simulation results verified that, under the conditions of output unchanged and steady, the improved control strategies performed better control effects in both the effectiveness and the input disturbance resistance of the system under corresponding working mode than the traditional double closed loop control strategy. Motor is a key components in electric vehicles, in this paper, a simple introduction of the control model of the asynchronous motor was made, and SVPWM vector control technology was applied to control the asynchronous motor. The simulation model of the induction motor drive system was established by Matlab/Simulink. Simulation results showed that the SVPWM control strategy was well meet the operation requirements of electric vehicle. Finally, the simulation of the electric vehicle driving system based on the bidirectional DC/DC converter were made, the simulation results showed that the design of the converter and its control strategies and the motor driving system has reached the operation of the electric vehicle drive system needs.