Research On Improved Buck Battery Charging Circuit

With the strong development of electric vehicles in many countries, its surrounding product development has also been a popular concern. Especially for the electric vehicle battery charging, has become an important issue on research. In recent years, batteries of electric vehicle have been constantly updated, lead to a more stringent requirements on the charging device. Owing to the simple control and the small volume of buck circuit, it is used in charging circuit widely.In this passage, the traditional buck charging circuit is researched in detail, analyzing the principle of the circuit, establishing the steady-state model and the AC small signal model, calculating the key transfer function in order to analyze the circuit harmonic sources of buck converter. When buck circuit is charging the battery, it is affected by the outside easily, because of lacking of the ability of high-frequency harmonics attenuation. So, we consider the filter of DC/DC converter, comparing the LC filter of buck circuit and the LCL filter, coming to a conclusion that LCL filter is better than LC filter in high-frequency attenuation.Therefore, in this passage we combine the LCL filter with the traditional buck circuit, get a new LCL-Buck charging circuit. And we analysis its stability, draw out the Bode diagram of the closed loop transfer function from the theoretical aspects to verify the correctness of the new charging circuit. In addition, the new LCL-Buck circuit simulation and experiment is preceded, also verify the correctness of the new charging circuit.