Research On Critical Problems Of Phase-shift Full Bridge Converter For Dc Charger Of EV

Electric vehicle has become a hot spot with the consideration about energy and environment. One of the critical tasks in the research of vehicle is to design a charger to provide safe and effective service for EV. This paper design a set of hign power and off-board dc charging system. With phase-shift full bridge ZVS converter as the main topology structure, with digital control method controlling it, completing a dc charging machine prototype foe EV and reach on several key problems of phase-shift full bridge ZVS converter.Firstly, this paper introduces the working principle of the phase-shift full bridge ZVS converter, analyzs several inherent problems of realization of soft switch, duty cycle loss and rectifier voltage peak, and design phase-shift full bridge ZVS converter for EV, including its hardware design and software.Secondly, in view of the phase shifting full bridge ZVS converter, study the problem of rectifier diode voltage ringing, propose five order equivalent model during converter shocked, through analyzing of the five-order model, voltage stress of rectifier diode can be suppressed by adjusting the size of the parasitic parameter. Facilitate the experimental verification, designing appropriate additional resonant inductance to adjust the parasitic parameters can effectively suppress voltage stress of the rectifier diode, moreover, it is possiable to remove the RC snubber circuit completely to further improve the efficiency of the system.Then, in view of the phase shifting full bridge ZVS converter, study the problem of voltage oscillation of transformer primary side, through the modeling of the system, analyzes the mechanism of oscillation and converter parameters on the influence of the oscillation, according to the simulation and experiment, the reasonable design of the RC snubber circuit parameters can effectively suppress oscillation of transformer primary side voltage, improve the overall efficiency and reliability of the system.Lastly, simulink of the charging system proved the feasibility of the system design, and complet prototype experiment in the design of the prototype platform for DC charger of EV, through the analysis of the experimental waveforms verify the correctness and feasibility of the system.