The Study Of High Power Factor Charger

With the development of the new battery technology and continuous improvement of fabrication process, the battery has been widely used in automotive and other industries. Charger is an equipment that recharges battery energy storage device, and its performance directly affects the service life of the battery, charging status and pollution degree of power grid. High power factor DC charger is proposed in this paper.Taking the practical application of the rectifier charging technology of the charger as the background, and understanding the basic principle, structure, characteristics and related theory knowledge of the battery charger, a high power factor charger with three-phase voltage source PWM rectifier topology is designed. Firstly, in order to facilitate the design of the control system, the voltage source PWM rectifier topology, the basic principle and the mathematical model of multiple coordinates is analyzed. The traditional software phase-locked loop strategy is analyzed, and then three-phase phase-locked strategy is proposed based on the single-phase rotating coordinate system, dynamic and steady state performance taken into account. The basic principle and implementation method of space vector PWM method are included in this paper. Using SVPWM modulation, grid side current harmonics can be reduced, and DC voltage utilization ratio can also be improved. In the last part, according to the basic requirements of battery charging, a double loop,voltage outer loop and current inner loop, is designed to realize constant voltage output, another double loop,current outer loop and current inner loop, is designed to realize constant current output. Then a battery energy storage system has been designed, which consists constant current output mode and constant voltage output mode.Based on the analysis of the above, simulation model of charger is constructed in the MATLAB/Simulink platform, an experiment prototype is made, and design method of main parameters is given. Charger in constant current mode and constant voltage mode has carried on the simulation and experiment. The results of the simulation and experiment has reached the experiment requirement. In the pure resistor load conditions, the grid side power factor reaches more than 0.99. The feasibility and effectiveness of control methods in the paper are confirmed by the experimental results of the prototype.