Research On Induction Heating Based On Wireless Power Transmission Method

Induction heating technology is often used in tumor hyperthermia.It uses the theory of electromagnetic induction,generating induced currents in the implanted medium inside the tumor tissue under the action of alternating magnetic field.The induced current leads to power loss which finally is converted to heat.In fact,the principle of induction heating technology based on coil coupling is very similar to the technology of magnetic coupling wireless power transmission.Induction heating technology based on magnetic coupling wireless power transfer(WPT)can effectively improve the power transfer efficiency(PTE)and transmission distance of induction heating.In this paper,a series of researches such as modeling and optimization of induction heating systems are carried out based on WPT methods.Firstly,based on the analysis of the two-coil magnetic coupling resonance circuit,the traditional two-coil induction heating system model and the derivation of the PTE formula is given out.The self-resonant induction heating model is introduced on the basis of the traditional induction heating model.Then,a minimally invasive tumor thermal therapy based on liquid metal is proposed.The injection method of a liquid metal coil is described.The operating frequency and coil size of the system are optimized.The calculation is verified by the simulation through Ansys HFSS simulation and experiments.Finally,the miniature implantable self-resonant coil hyperthermia system is studied.In order to avoid reducing the PTE because of non-resonant without a compensation capacitor at receiving end,the parasitic capacitance of the receiving coil is used as a compensation capacitor.The multi-turn spiral coil is used to reduce the self-resonant frequency of the receiving coil because of its relative large capacitance.A ferrite core with a Curie temperature of 48°C is inserted in the center of the coil to improve the values of the capacitance and also the efficiency while also achieving temperature control for the heating process.With the goal of maximizing PTE,the system operating frequency and coil parameters are optimized.The model is verified through simulations and experiments.The power transmission efficiency is increased from 4% of the traditional implantable metal coil to more than 7% of the proposed system.