Research On V2G Charging Pile DC/DC Converter And Its Control Strategy

In recent years,with the maturity of electric vehicle technology and the enhancement of social environmental awareness,more and more people choose electric vehicles as travel tools,and the Vehicle-to-grid(V2G)system can realize the interaction between electric energy and power grid power in the electric vehicle lithium battery.It can not only pass through the power system when the power system is too heavy.The lithium battery is fed to the power grid,and the power grid can not be used in the power grid.The power grid can not be used in the electric vehicle lithium battery at a cheaper price.It can realize the peak shifting of the electric energy,reduce the investment of the power system,and reduce the charge cost of the electric vehicle.Therefore,V2 G technology will be an important part of smart grid in the future.It involves new technologies such as power grid monitoring,battery energy management,and power conversion and transformation.As an important link in the electric energy conversion,the two way flow "transfer station" between the power grid and the electric vehicle has put forward higher requirements for the converter.This paper first introduces the basic concept of V2 G system,the application prospect of V2 G technology in power grid,and the research status of V2 G system at home and abroad.The advantages and disadvantages of the electric energy conversion topology in the V2 G charging pile are simply explained and compared.The functions of the power converter in the V2 G charging pile system are analyzed and the characteristics of the various kinds of power converters are analyzed and compared.A type of two stage power converter topology is selected and the two stage power converter is extended.With the switch tube and the voltage and current waveform of some important devices,the basic working principle of the converter circuit is explained with the switch tube and the voltage and current waveform of some important devices.The parameters of the components of the circuit are set up with the possible actual V2 G work and the requirements of the V2 G system.Then by calculating the equivalent duty ratio of the phase shift full bridge circuit and combining the mathematical model of the non isolated circuit,the design of the mathematical model and the compensation link for the bidirectional converter system is carried out.The control strategy design part,focusing on the charging requirements of the lithium battery in the V2 G system,and the demand for the feedback power of the front stage AC/DC converter,and by changing the P value in the traditional PI control to study the effect on the output of the DC/DC converter,and then design a variation rate of the output voltage and the expected voltage and the difference rate of the difference.To change the fuzzy PI control of the P value,the fuzzy PI control strategy is obtained through the simulation experiment.When the DC/DC converter is forward charging,the response speed of the output voltage and the accurate value are closer to the best charge curve of the lithium battery.The power grid overpower can be stored more in the lithium battery at the same time,thus improving the power grid adjustment.Power saving;when feeding,the DC voltage needed for the AC/DC converter can be quickly and accurately output.At last,a prototype of the converter based on fuzzy PI control is designed.The main composition of the converter is explained,the main work waveform of the converter is intercepted and the converse efficiency of the converter is calculated.Thus,the fuzzy control is proved to be suitable for the system charging pile converter.