Control Method Of Soft-switching Of Voltage Full Bridge Inverter Of EV Wireless Charging System

In the current wave of social efforts to promote the development of green energy,electric vehicle play an important role in reducing environmental pollution and developing green travel.At the same time,in order to ensure the security,flexibility,rapidity and real-time requirements of electric vehicle charging,high power and high efficiency electric vehicle wireless charging technology emerged as the times require.It is developing rapidly towards industrialization.However,when electric vehicle are charged by static wireless charging,the deviation of parking position and the change of charging power will cause the change of system parameters.The change of system parameters will affect the soft-switching of the system,and then affect the transmission power,efficiency and device life.This paper takes the static wireless charging of electric vehicle as the background.It introduces the basic principle and composition of the static wireless charging system of electric vehicle.This paper analyses the load characteristics and soft-switching principle of voltage full-bridge inverter commonly used in the system.It analyses the influence of parking offset and charging distance on mutual inductance of primary and secondary coils of electromagnetic coupling mechanism.It also analyses the influence of mutual inductance on the resonant frequency and transmission power of the system.Then it analyses the influence of the change of resonant frequency and transmission power on the working state of voltage full-bridge inverter soft-switching.It shows that the traditional soft-switching control method can not adapt to the change of parameters.Therefore,we need a soft-switching control method that can adapt to the change of parameters.Through analysis and summary,it also proposes a soft-switching control method for voltage full-bridge inverter in static wireless systems of electric vehicle.It has strong adaptability to the change of system parameters.It includes the method of switching position control of inverter drive and dynamic adjustment of dead-time of drive.Through the combination of these two methods,the voltage full-bridge inverter soft-switching of electric vehicle wireless charging system can be realized well.It is of great significance to improve the transmission power and efficiency,reduce switching noise,reduce device stress and improve the stability of inverter.The thesis use Cadence/PSpice simulation platform to build the simulation model of traditional soft-switching control.It analyses the working state of voltage full-bridge inverter under the condition that the parameters of the wireless charging system of electric vehicles change.It is proved that the soft-switching can not be realized when the system parameters change.Then the paper designs the main circuit,driving circuit and soft-switching control circuit of MC-WPT system,and chooses the main components.Finally,an experimental verification device is built.Experiments show that the soft-switching control method proposed in this paper can realize voltage full-bridge inverter soft-switching of electric vehicle wireless charging system.