Research On Charging System Based On PWM Rectifier Technology

Because of battery's own recycled to charge and discharge, easy to carry,safe and reliable, has been widely used in telecommunications, navigation, aviation, medical and other fields, and the requirement of charging device is also rising. This paper designed a high efficient battery charging device.Most of the main circuit of charging device is two-stage structure, PWM rectifier and DC/DC chopper. PWM rectifier has been successful applied in many fields such as Active Power Filter (APF), Static Var Compensation (SVG), ac moter drive in four quadrants,Unified Power Flow Controller (UPFC), and so on So a variety of PWM rectifier circuit topologies have been developed in order to meet different requirements. The most commonly used is three-phase voltage source PWM rectifier. This topology has the advantages of low THD, power factor closed to 1, two-way power flow and good dynamic performance, DC/DC,chopper adopts Buck circuit, making the system meet the needs of step-down charging.In this paper, on the basis of consulting a large number of literature, firstly analyzed the principle of the system. Established mathematical model after understanding the system topology and converter process, and then calculated parameters of the main circuit and determine the device type.Secondly the system control strategy was studied, the main research direction for the SVPWM control strategy and direct power control (DPC) strategy. The principle and realization method of the two control strategies were showed. Analyzed conventional switching table based on the theory of instantaneous power in the two-phase static coordinate.And analyzed switching vector's influence on the instantaneous power. After that, put forward a new method of sector division and new switching table. Finally compared different kinds of charging method, and determined the charging mode: constant current and constant voltage charging mode.The simulation software Matlab was used to make simulation study on the system. Then,the real circuit based on TMS320F28335 was made. Both simulation and experimental results all showed the feasibility and superiority of the method.