Research On High Efficiency And Safe DC/DC Converter For Electric Vehicle

With the environmental pollution and energy crisis and other issues have become increasingly prominent,the world are actively developing new energy industry.New energy vehicles as a representative of the field of new energy has a wide range of people attention with its environmental,technical,economic and other advantages.The bidirectional DC / DC converter as the electric vehicle energy transmission of the middle parts,not only the power battery can be passed to the motor,the car can also be regenerative braking energy back to the energy source,so the energy efficiency is greatly improved.Therefore,it is of great practical significance to design a DC / DC converter with two-way energy flow,low cost,high efficiency,good dynamic performance and high safety.In this paper,the staggered parallel bidirectional DC / DC converter is used as the object of study.It is designed by installing the Schottky diode,hardware protection and software protection with a high efficiency and safe DC / DC converter.Finally,the designed DC / DC converter is experimentally verified by the hardware circuit through STM32F4 as a control platform.Firstly,this paper analyzes the topology of the bidirectional DC / DC converter.Based on the analysis of various topologies and efficiency,it selects the interleaved parallel two-phase bi-directional half-bridge converter as the main circuit of this study.Then,it analysises the working principle of the main circuit in detail,and the corresponding Boost and Buck working modes of the converter are given when the electric vehicle is in different running state.Then,the paper designs the converter and selects its device.This paper analyses the loss of the components in detail,and obtains the loss distribution of the converter.Finally,this method improves the efficiency of the converter by the parallel Schottky diode.Secondly,aiming at the two different working modes and the demand of the converter,the paper clarifys the control objectives of the bidirectional DC / DC converter in two different working modes,and uses the state space averaging method model the system.The paper deduces the small signal model in detail.On this basis,it design two closed-loop controllers respectively.Finally,it carries out the closed-loop simulation of the model by SIMULINK,which fully validates the rationality of each parameter design.Then this paper give the hardware design,construction and software design of the converter system.Among them,the hardware circuit is composed of drive circuit,main circuit,sampling and conditioning circuit,protection circuit and other modules.The software part of the sampling signal including AD conversion and processing,control PWM signal generation,PI operation and overvoltage overcurrent protection and other parts.Finally,through building the experimental platform,the hardware circuit is tested in Boost mode respectively,which verifies the correctness of the theoretical derivation.