Research On Wireless Energy Transfer System Based On Magnetic Coupling Resonance

With the development and progress of society,the demand for electrical energy in human society is increasing.Wireless power transfer(WPT),which realizes the wireless transmission of electrical energy under the condition of non-physical contact,has received more and more attention and research as a new type of energy transmission.The research of wireless power transfer technology in this paper mainly focuses on the analysis of transmission characteristics of wireless power transfer system based on the principle of Magnetic Coupling Resonance(MCR)and the design of adaptive power tracking system based on impedance matching.The main research contents and contributions of this thesis are summarized as follows:1.The transmission characteristics of the wireless power transfer system are studied,and the wireless power transfer system is modeled using a variety of methods,based on which the load conditions for its maximum power transmission and maximum efficiency transmission are derived,and it is related to the quality factor of coils,coupling coefficient,mutual inductance,etc.,which simplifies the analysis results.The coupled mode analysis method is used to analyze the static and dynamic energy changes in the coils,and the analysis method for analyzing the transmission characteristics of the multi-coil series system using the transmission matrix is proposed to simplify the analysis process.2.Analyzed the design method of passive and active impedance matching network of wireless power transfer system,and the realization method of maximum power point tracking(MPPT)and maximum efficiency point tracking(MEPT)based on impedance transformation.The principle,realization method and application scope of different impedance transformation methods are expounded,in which the active impedance matching method using DC-DC converter is emphasized.The working principles of three common DC-DC circuit topologies are analyzed,and their respective applicable ranges are summarized.3.Designed an adaptive MPPT system based on the principle of the perturbance and observation(P&O)method control strategy,and combined it with the MCR system to implement a wireless power transfer system with adaptive MPPT function.In the design process,the principle of the P&O control strategy is analyzed in detail,and the control strategy is realized by two methods,circuit method and program method,and multiple sets of experiments are designed to verify the analysis.Then,a method of introducing different order derivatives of output power to duty cycle to change the step size in the tracking process is proposed,which can track the maximum power point faster.Compared with the design of the similar literature,the adaptive MPPT system designed in this thesis greatly reduces the volume while realizing the function.Experimental results show that the adaptive MPPT system designed in this paper achieves the function of maximum power tracking,and the improved tracking method proposed improves the tracking efficiency by 44%.This provides a design reference for the design of wireless power transfer systems that require corresponding speed and small size.