Modeling And Control Of Wireless Power Transfer System With Bidirectional Energy Interaction

Wireless power transfer(WPT)with bidirectional energy interaction,abbreviated as bidirectional wireless power transfer(BD-WPT),factions as both one of important branches and one of researching hot topics in the sector of WPT.Convinent and flexible as it is,BD-WPT promises a wide prospect in the case of power interaction between electric vehicle and grid,owing to its emerging merits that it is capable to realize free power flow between source and load.In this thesis,research work on BD-WPT can be briefed as follows:In the first place,electrical model,equvilent circuit model and corresponding mathematic model of BD-WPT were established orderly.Via those models,the operational principle of BD-WPT system was discussed and mathemathical expressions of transmission power and power transfer efficiency(PTE)were derived.In addition,the phase shift voltage control,the regulation scheme of transmission power,was porposed with in-depth analysis of factors impacting transmission power and PTE.Moreover,for one part,in terms of transmission power,maximum PTE,PET stiffness and coil misalignment,compared analysis was carried on LC-type BD-WPT and LCL-type BD-WPT system.For another part,probe coil unit was invented to monitor key system paprameters including phase difference and voltage ratio of primary side and secondary side,whose feasibility was also validated by simulation and experiments.In the second place,theoretical analysis was carried on BD-WPT system with multiple energy cells(EC).The compound control scheme of "voltage and phase" was introduced to make power flow flexibly among energy cells.Meanwhile,take BD-WPT system with 3 energy cells as an example,differenet power flow directions were discussed and their corresponding constrain relations were presented based on "zero reactive power" rule.Additionaly,on the one hand,compared analysis among the same power flow direction but with different constrain relations were done from the view of transmission power and PTE.On the other hand,theoretical research went to the optimal energy interaction point selection with PTE optimization as a target.At the last of this part,both low power level experiment and high power level simulation were designed to verify those proposed theory and validate the control scheme.Finally,the laboratorial prototype including resonator,re-charge battery,H-bridge converter and its controller was built.The hardware developed experience on H-bridge converter and its controller was shared.