High-efficient battery charging system based on current-source PWM rectifiers

CSR(Current-Source Rectifier) is adopted as the system topology of large-power charging system to improve its battery voltage adaption and charging efficiency. The indirect current control strategy is employed to carry out the delayed correction of grid-side voltage signal for the unit power factor control at grid-side. Based on the traditional CC-CV(Constant Current-Constant Voltage) charging mode, a CC-CV switchover algorithm based on the fuzzy-reasoning control strategy is proposed according to the electrochemical characteristics of the battery. The frequency-domination method is applied to analyze the transfer function of control loop in the CV charging mode and the impact of digital time delay on charging system is considered. In order to improve the overall performance of charging system, the MATLAB/SISO design tool is applied to optimize the zero-point position of loop controller and the loop gain for inner current loop and outer voltage loop. The correctness and feasibility of the proposed strategy are verified by the simulative and experimental results. ©, 2015, Electric Power Automation Equipment Press. All right reserved.