Device Current Voltage Stress Suppression Method Of Wireless Charging System For Electric Vehicle

The wireless power transfer technology is applied to the electric vehicle wireless power supply system(Electric Vehicle Wireless Power Transfer,EV-WPT).For lifespan of wireless power supply system,i.e.Mean Time Between Failure(MTBF),there is requirement on analysis of voltage and currency stress of device for electric vehicle wireless power supply systems.This paper concentrates on analysis of voltage and currency stress control,i.e.Influence of key component topology and indexes at steady status and transient stress control,etc.EV-WPT system enables non-contact electric charging.Its main parts include power conversion device on ground,power conversion device,coupling mechanism and resonance compensation network.The topology of power conversion device and resonance compensation network will directly influence on device stress.At the same time,rectifications of index in coupling mechanism and resonance compensation network will also generate changes in device stress.The research and development do not have a comprehensive standard for measurement of steady status stress for components of wireless charging system.Moreover,there is no scientific reference for determining rationality and performance of key topology according to the standards.Meanwhile,time variability of system parameters and intervention factors in operation of EV-WPT will also contribute to acute increase of voltage and currency stress of components and thus challenge MTBF system.On one hand,there exists the requirement of designing and optimizing the system parameters.On the other,it is required to take comprehensive consideration of the strategy of dynamic control according to time variability of system parameters.The purpose of this is to limit component stress in process of charging.At the same time,the system is supposed to be qualified in stability and implementability and other properties.The main content of research and work of the thesis:The low voltage and currency stress topology of EV-WPT system.Confirming that object of the study includes switch tubes and reduction design of capacitance inductor,so as to determine value of component stress at optimistic MTBF.Besides,the paper compares different influences on voltage stress of invert tube between full-bridge inverter topology,half-bridge inverter topology,push-pull inverter topology and E inverter topology,the influence on rectifier tube voltage stress of full-bridge inverter topology and half-bridge inverter topology,the influence of SS resonance topology and LCC-LCC resonance topology on capacitive,inductance and switch tube currency and voltage stresses.By focusing on coil parameters of the coupling mechanism and resonance parameters of resonant compensation network,the paper studies their relationships with component currency and voltages.In the end,the paper selects the optimal topology and appropriate parameters for construction of charging systems of electric vehicles.Dynamic control methodologies of device voltages and currency stress in EV-WPT Sytem.It proposes the methodology of phase-shifting control,which outputs varied powers at different phases according to dynamics of loads,so as to maintain stress of system components at low level.Moreover,the paper researches transient state process of phase-shifting control and proposes a way of adjusting resonance parameters that keeps the system at low sensibility,so as to eliminate the peak currency at time of opening and maintain transient currency stress of the rectifier tube at optimal state.For acquiring real-time dynamic control and quick reaction of voltage and currency stress of components,fuzzy PID algorithm is employed for control strategy.Creativity contribution of the paper is in that:For resonant compensation network topology in EV-WPT system,the paper provides scientific reference for determining rationality and performance of topology.In the end,this paper suggests phase-shifting on the basis of fuzzy PID which guarantees that component stress is with safe sphere throughout charging process while parameters of EV-WPT system has changed.