Research On DC Fast Charging ZVS Control Of Electric Vehicles

Under the dual pressure of the energy crisis and environmental pollution,this has led to the zero pollution,zero emission,high efficiency and energy saving electric vehicles are favored by people.The development of electric vehicles,which have been positioned as a national strategy by many countries.That must be equipped with adequate charging facilities,however,the traditional mode of AC slow charging has been unable to meet people's fast-paced life,therefore DC fast charging mode arises at the historic moment.In this paper,the DC-DC phase shifted full bridge ZVS for DC fast charging power supply module is deeply studied.I completed the following work:At the beginning of this paper,the current situation and existing problems of DC charging through reading a large number of domestic and foreign relevant literature and making market survey.The main circuit is determined by comparing the common DC-DC circuit topology.The necessity of phase shifted full bridge ZVS soft switching technology in high power direct current charging,and the working process of PS-FB-ZVS converter are discussed.A double closed loop control strategy with better stability and dynamic performance is proposed through comparing and analyzing the principle of DC fast charge and its charging methods.Furthermore,due to the shortcomings of the PI algorithm,the integral separation PI algorithm is presented.The key components of the main circuit are designed,calculated and selected.The hardware circuit of the control circuit is designed.The digital realization process of integral separation PI algorithm and phase shifted full bridge PWM is given.Based on TMS320F28335,software design and development is carried out.Under the condition of parasitic parameters,an effective duty cycle expression with higher modeling accuracy is introduced,and the small signal model of phase shifted full bridge ZVS converter is established by using the state space averagingmethod.This modeling method is the innovation of the article.The simulation results show the correctness of the modeling method.The double closed loop DC-DC system model is established and simulated by matlab,results show that the proposed method is effective for ZVS control,and the output is stable and fast.Finally,the experimental platform is built.The experimental results show that the phase shifted full bridge ZVS is realized,and the output voltage is stable and smooth,besides,control and detection,as well as protection function is normal.Which laid the foundation for further research on the key technologies of DC fast charging.