Research On Electric-field Coupled Wireless Power Transfer Technology For Biomedical Application

In this paper,based on the research of wireless power transfer in the field of biomedical applications,the key technologies of Electric-field Coupled wireless Power Transfer(ECPT)are studied.In order to improve the output power of ECPT,the impact factors and the coupling models of the coupling capacitor,the matching methods,and the output power are studied.The research contents of this paper are as follows:(1)The research background and significance of ECPT,as well as the development status of two cases when air or biological tissue as medium are introduced.The factors affecting the coupling capacitance are analyzed one by one,and the coupling models with air and biological tissue as the medium are analyzed.(2)The difference between different matching methods is analyzed and verified.Currently,when compensating for the reactive power of the ECPT system for biomedical applications,the indispensable cross-coupling resistance generated by biological tissue is neglected,and the calculation method of the imaginary part of the input impedance is rough.In this paper,the cross-coupling resistance generated by using biological tissue is considered.The calculation method of input impedance is given according to the circuit model,and the difference between the two calculation methods is compared and analyzed by MATLAB.(3)A novel matching method is proposed.For the ECPT system for biomedical application,the existing research only performs inductive matching by using an inductor to compensate the reactive power generated by the capacitor.In this paper,combined with the structure of the coupling circuit with biological tissue,the LC-type matching of the circuit is proposed while considering the influence of the cross-coupling resistance generated by the biological tissue.The calculation methods and expressions of matching component values and output power under different matching modes are shown.The optimization effect of LC-type matching on improving output power is verified by using simulation(ANYSYS HFSS)and experiments.(4)From the results of LC-type matching at the transmitting end,there is a tendency that the output power firstly increases and then decreases.A maximum output power point can be found.In this paper,it is verified by experiments that the peak of the output power can be achieved under any load condition by using appropriate impedance matching circuits.