The Research And Implementation Of DC/DC Converter Topology Structure Of Mild Hybrid Vehicles

With the pressure of national energy increased gradually and related regulations on vehicle fuel consumption become more stringent,the orginal 12 V idle start and stop system can not meet the requirements because the system voltage is low,promoting automakers start the research of 48 V idle start and stop system.But using high voltage system make switch control between engine and motor is difficult,and the cost is higher,the 12V+48V system came into being.12V+48V system only increased48 V network on the existing 12 V system,continue to use the existing mature 12 V network technology,reduce the cost,and the direction of its development in accordance with the future of pure electric and full hybrid technology.This paper relies on the project of 12V+48V automobile power supply system in Shanghai Delta Electronics Design Center,making a48V/12 V DC/DC converter,achieving the power from the 48 V lithium battery to 12 V lead-acid battery.The main research work of this paper is as follow:Firstly,according to the requirements of parameters of the car charger,this paper designs the topology of converter,elaborates on the working principle of four phase interleaved DC/DC converter by synchronous recitification,on the basis of this converter,the type of power converter switches,the parameters of inductor,filter capacitor are given,and the protection circuit and drive circuit are designed.Secondly,this paper analysises the causes of generate voltage spikes of DC/DC converter in the process of the work,discuss several common methods of suppressing converter voltage spikes,proposes the suitable design scheme of suppressing spike voltage for the topology,and verifiesthe feasibility with simulation.Thirdly,aiming at the shortcomings of converter becomes larger and heavier because it adopts multiphase interleaved topology and use many magnetic components.This paper adopts the method of magnetic integrated to reduce the converter volume,lighten the weight of converter.In this paper,the intensity and the distribution of the magnetic flux and magnetic flux density of the integrated inductor in different operation modes are analyzed,and the parameters of the new integrated magnetic components and the loss of the integrated magnetic components are designed and calculated.Fourthly,the production of car converter is manufactured,set up an experimental platform to verify the feasibility of the design.