Research On IPT Resonant Converters With High Misalignment Tolerance By Multi-output Combination

Inductive power transfer(IPT)technology has the advantages of wide range of power capability and high efficiency.Since IPT is relatively mature,the IPT technology has been widely used in a variety of application.However,the physical movement between transmitting and receiving coils is inevitable in practical charging systems,impairing the output characteristics.In order to solve this problem,this thesis attempts to make an in-depth study of the modeling of contactless transformer under misaligned condition and the optimization of IPT resonant converters to achieve high misalignment tolerance.Firstly,this thesis reviews the key technologies of inductive power transfer,summarizes techniques for the improvement of contactless transformer and points out that multi-output combination is an effective method to improve the misalignment tolerance of IPT resonant converters.Then,a new model for calculating the coupling coefficient is developed based on null coupling position calculation and the change law of the coupling coefficient curve under different alignments.Two typical contactless transformers using DD and circular coil structure are constructed,whose detailed modeling steps are given.The calculated coupling coefficient is verified with experimental measurement to be very accurate.Furthermore,a novel magnetic structure called the DD2 Q coil sets is proposed to help achieve larger tolerance.Then,two IPT resonant converters,which adopt S/P compensation with multi-output connected in parallel and LCL/S compensation with multi-output connected in series,are taken as example to study the operating characteristics,including the various operating modes,operating boundary conditions,quantitative derivation of input-to-output voltage gain and input impedance and design principle of contactless transformer with multiple receiving coils.Two 100 W experimental prototypes are fabricated to verify the theoretical analysis.Experimental results show that the proposed IPT resonant converters by multi-output combination have good tolerance to misalignments.The output voltage gain changes by less than 50% within the range of 50% lateral misalignment,50% longitudinal misalignment and 90° rotational misalignment.The maximum efficiency of the parallel connected converter is 93.147% under full load condition.