Research And Development Of Electric Vehicle Charging Pile Converter And Control Technology

With the aggravation of environmental problems such as global energy crisis and air pollution,electric vehicles have gradually become a new mode of transportation.The zero-voltage zero-current switching(ZVZCS)full-bridge converter using pulse width modulation(PWM)technology has the advantages of simple control,high transmission power and high efficiency,and has become an important circuit form of DC/DC module for one-way charging piles;Dual active full bridge(DAB)bidirectional converter has good dynamic response and power transmission.With the advantages of strong transmission capacity and bidirectional power flow,it has gradually become the core circuit of DC/DC module of bidirectional charging pile.Therefore,the performance optimization of ZVZCS PWM full-bridge converter and DAB converter has become a research hotspot and has important practical significance.This paper will optimize the performance of ZVZCS PWM full-bridge converter and DAB converter from two aspects of dynamic performance and efficiency.Firstly,the ZVZCS PWM converter is studied.This paper analyses the working principle of ZVZCS PWM converter,establishes the small signal model,designs the compensation network of PI double closed-loop control and analyses the open-loop Bird diagram.To solve the problem of poor dynamic performance of ZVZCS PWM converter under PI double closed-loop control,sliding mode control(SMC)is introduced in this paper.The outer-loop sliding mode control and inner-loop PI(SMC-PI)control methods are adopted to improve the dynamic performance of ZVZCS PWM converter.The simulation results prove the superiority of SMC-PI control method.Then the DAB converter is studied.Aiming at solving the problem of poor dynamic performance of single-phase-shifted DAB converter under PI control,this paper adopts the method of model predictive control(MPC).To simulate and compare with PI control and load current feed-forward control,the paper builds an experimental platform with TMS320F28335 as the controller to test DAB converter under three control modes.Load shedding experiments were conducted to verify the excellent dynamic response characteristics of predictive control.In view of the backflow problem of DAB converter under single phase shift control mode,the system efficiency is affected.Based on the extended phase-shifting control method,an extended phase-shifting control method with fixed internal phase-shifting angle is adopted in this paper.The theory shows that the control method can reduce the backflow power and current stress of DAB converter.At the same time,the simulation analysis and experimental verification of the DAB converter under the extended phase-shifting control mode with fixed internal phase-shifting angle prove the effectiveness of the control mode.