A Method Of Coil Design And Optimization Of Magnetic Resonance Based Wireless Power Transmission System

In 2007,a new method of wireless power transmission based on magnetic resonance coupling theory was proposed by scholars of Massachusetts,who lit up a 60 W wireless bulb 2 meters away from the power supply.When the the distance was shortened to 1 meter,the transfer efficiency was up to 40%.Compared with conventional electromagnetic induction wireless power transmission technology,the transfer efficiency of resonant wireless power transmission system is higher,and transmission distance is longer.Therefore,electromagnetic resonant wireless power transmission technology has broader application prospects in the healthcare field and consumer electronics.At present,there were still relatively few researchs was made on optimization of parameters of resonant coils for magnetic resonance energy transmission system.Two parameters of the resonant coils,coupling coefficient k and quality factor Q,play a crucial role in transmission efficiency of the system.Therefore,properly optimization and design of the parameters appear particularly necessary.In the practical application,the four coils structure resonant wireless power transmission system has more advantages than two or three coil system,and becomes a research hotspot.In this paper,magnetically coupled resonant wireless power transmission system,as well as it's coil design and optimization was studied.First,the current development situation of wireless power transmission technology is analyzed and studied.Comparison has been made for different types of wireless power transmission technology.And the advantages and necessity of the study of magnetic coupling resonant wireless power transmission is presented.Based on equivalent circuit model,the transmission efficiency,transmission power and the frequency splitting of the basic two coil structure system are analyzed.Furthermore,the transmission efficiency of the popular four-coil structure magnetic coupling resonant wireless power transmission systems is analyzed with emphsis.Second,for the purpose of improving the system transmission efficiency,theoretical analysis of optimizing the coil is made.Planar spiral coil structure is selected which can save space.When the frequency of the power supply,the coil area and wire radius are fixed,the turns and winding space of the coil should be optimized reasonably so that the product of the quality factor and coupling coefficient of the two relay spiral resonators coil is maximized,thereby overall system transmission efficiency is improved.Moreover,series of electromagnetic simulation for coil model was conducted by using ANSYS Maxwell.Parameters of the coil model were extracted,and then resonant coils optimized.The Maxwell and Simplorer joint simulation results show the correctness of the optimization method.Finally,several groups of coils were wounded,and a four-coil-structure experimental resonant magnetic coupling wireless power transmission system was built.Multi-group analysis test comparison was made.The experimental and simulation results have good consistency,and the correctness of the optimization method of coil was verified by the simulation and experimental results.