Research On Lithium Iron Phosphate Battery Fast Charging System

Power Battery is the core energy of Electric vehicle,in which Lithium Iron Phosphate Battery is the best choice because of its high security, power, environmental protection and long life. At present, the research on fast charging methods of lithium iron phosphate battery is a hot point. However, most of the research is for the batteries voltage above 300V, the fast charging method for voltage blow 48Vbattery is researching very little. Based on the charging requirements of 48V lithium iron phosphate battery pack, designed a rapid charging main circuit topology and its control method, built charging experimental platform and completed the battery fast charging experiment. The following work has been completed specifically:â‘ Main circuitCompared the electric car charging methods, according to the actual needs, choose 3-Phase Current Source Rectifier (CSR) as charging main circuit. Analyzed the principle of CSR and established CSR mathematical model. Analyzed and compared several major control method of 3-Phase CSR,and mainly researched the SPWM ternary logic and SVPWM current space vector control methods detailed.â‘¡SimulationBased on the analysis of the charging main circuit and the study of the control method, established the Saber simulation model. Both SPWM and SVPWM simulation have been analyzed, and SPWM control method has been simplified. The simulation results verified the feasibility of the circuit and control method, and the parameter selection of main circuit was optimized by simulation.â‘¢Experiment and test methodsCompleted a three-phase current source rectifier main circuit hardware design and built the experimental platform, the software debugging implemented based on the modular design. Completed the open and closed loop experiments, achieving power factor correction, verified the correctness of the simulation. A group of Lithium iron phosphate batteries has been charged by different current, experimental results showed that this method can output constant large current realize the electric car batteries rapid charging.â‘£Conclusion Using three-phase Current Source Rectifier as the charging circuit that can output size adjustable charge current for wide range voltage, achieving power factor correction. Lithium iron phosphate group can fast charge in a safe range, demonstrated the feasibility and superiority of charge.