The Research Of Electric Vehicle Intelligent Charging System Based On Dynamic Estimation Of SOC Values

As the proble m o f energy and environme nta l around the world become more andmore serio us, the deve lopment of clean and inte lligent electric vehic le (EV) has beenone of research hot topics around the world. However, inte lligent, effic ient, safe andfast charging techno logy of EV has been lagging behind the develop ment of its bodytechno logy. There fore, the research about inte lligent c harging s ystem o f EV hasbecome one of the important research directio ns in the research fie ld of EV in recentyears. On this background, this paper ma inly focuses on the EV inte llige nt chargingsystem to carry out the related research work. The main researches are as follows:Firstly, the characteristics of several k inds of commo nly used power battery areintroduced. Based on the analys is of Ni-MH battery’s characteristics, the equiva lentcircuit model of Ni-MH battery is establis hed comb ined with related experimenta ldata. And the battery parameters are identified by the least squares.Secondly, severa l trad itiona l estimation a lgorithms of power battery SOC(State-of-charge) va lue are co mpared and ana lyzed, and the basic princ ip le of thelinear Kalma n filter and Extended Kalma n filter (EKF) are ana lyzed. On this basisand comb ining the equiva lent model o f Ni-MH battery, an improved EKF method toestimate Ni-MH power battery SOC values is provided. Specific imp leme ntationsteps of it are given in details, and then it is validated by simulation.Third ly, on the basis of comparison and analys is on several traditio na l chargingmethods, a four-paragraph inte lligent c harging method is put forward, which c hoosethe way of charging based on power battery SOC values. The basic functio n and thetopology structure of the electric ve hicle inte lligent charging syste m areanalyzed.Then working princip le and control strategy of the three-phase voltagesource PWM rectifier and bi-directional DC/DC converter are analyzed in detail.Fina lly, the s imulatio n mode l of the electric vehic le intellige nt charging s ystemwhich based on dyna mic estimation about SOC values is estab lished. The simulationresults verify the correctness of the intellige nt charging method that proposed in thispaper. Then the software flow charts about it are given in details.