Research Of Electric Vehicle Phase-shift Full Bridge DC/DC Converter

DC/DC(direct current to direct current) converter is an indispensable part of electric vehicle, by the DC/DC converter, it can achieve different voltage output under high voltage direct current voltage system so that meet the vehicle electricity demand of low voltage electrical components. With the development of the DC/DC converter, the volume, efficiency and steady state performance put forward higher request.This paper mainly aims at a certain electrical passenger vehicle system of high voltage direct current voltage for high voltage switch to low voltage(336V/13.7V) DC/DC converter. The DC/DC converter adopts the lagging bridge arm series diode full bridge phase shifting control topology structure, to achieve zero voltage and zero current switching(Zero Voltage and Zero Current Switching, ZVZCS) of soft switch technology, which reduce the switching loss and improve the efficiency of converter. In order to realize the soft switch. The main circuit power devices, capacitors, resistors, transformers, inductors and other components of the parameter were designed, an the moment,which provide a theoretical basis for the follow-up research.Secondly, average switch modeling for the lag bridge arm series diode ZVZCS converter so that acquired more accurate transfer function. Average switch modeling method by converting the nonlinear model of the DC/DC converter to small signal alternating current equivalent model, and based on small signal alternating current equivalent model, get the DC/DC open-loop transfer function. Control method adopts voltage and current double closed loop PI control. After the PI controller parameters is designed by the open loop transfer function, the stability of the closed-loop feedback control of the whole system is analyzed based on the Potter diagrams.Finally, according to the characteristics of the phase shift control, set up a phase-shifting control model by PSIM simulation software, completed the closed-loop stability analysis, the simulation results show that the proposed control strategy has good stability and fast dynamic response, which proved that average switch modeling to get transfer function control theory is reasonable and reliable. Finally completed the prototype, the experimental results show that the presented average switch modeling method for transfer function and the double closed loop control strategy achieve the DC/DC converter targets, and the system has good stability, too.