Research On Electric Vehicle On-board Charging System And Control Strategy

Nowadays,environmental pollution and energy shortage are becoming more and more prominent in society.Electric cars are driven by electric energy,which has the advantages of environmental friendliness and high energy conversion rate.Vehicle charger is the core component of electric vehicle power charging,which is one of the factors restricting the development of electric vehicle.Charging equipment by the integration of power electronic devices,has impact,nonlinear and asymmetry,the charging process can cause the grid side power quality fluctuation,damage to the normal operation of the electrical equipment and power grid load large interference.Need high quality car charger,therefore,to improve the electric car charging in the process of the above problems,this paper designed a kind of high power factor,low harmonic,high power electric vehicle charging system,design and research mainly from the following several parts:Power battery characteristics of commonly used comparison,choose energy than large,high safety,limited overvoltage charge characteristic of lithium battery charging as object,combined with the existing rapid charging technology,puts forward a fast constant current constant voltage charging way;Based on the analysis of the traditional electric car charger,on the basis of topology,chose two levels of charging topology,its former level is the AC/DC converter,which has the function of APFC after class is the application of soft switch technology of DC/DC converter.Three-phase voltage source PWM rectifier circuit is analyzed,calculated the main components of the circuit parameters,under static coordinate system and dq two-phase rotating coordinate system mathematical model is established,and based on instantaneous power theory to realize the active power and reactive power decoupling.Three-phase PWM circuit of the double closed loop PI control algorithm,voltage outer loop control the DC voltage rectifier,outside the current inner ring is in accordance with the voltage current control loop of the output current instruction,former level was validated by the simulation model of AC/DC three-phase PWM rectifier output voltage response speed,high stability.Analyzed the working principle of the phase shifting full bridge ZVS converter,according to the Buck converter model calculated the small signal model,the phase shifting full bridge converter adopts method of average current control strategy,the main components of the circuit parameter design,calculate the transformer turn ratio,resonant inductor,filter capacitor,energy storage inductor parameters,such as components are simulated under Matlab software,the simulation results show that the charger level after the phase shifting full bridge ZVS converter output voltage stability,small range.Through Matlab/simulink simulation of vehicle charging system as a whole,the results show that the charger is able to within 0.2 s stable output voltage of 200 v,and ensure that can maintain the same phase,the net side current and voltage current total harmonic distortion rate is less than 5%,the design of electric vehicle charging system meet the design requirements.