| In this paper,a MCR-WPT(Magnetic Resonance Coupling Wireless Power Transfer)system for household appliances with sufficient magnetic shielding effect,excellent transmission performance and good load compatibility is studied.The system does not use traditional ferrite as magnetic shielding material,instead the coupling coil adopts a special Halbach type structure to achieve better magnetic shielding effect.Through the design of impedance matching network,the energy transmitting module of the system can supply power to electrical equipments with different loads,which solves the disadvantage that each electrical equipment needs to be equipped with a separate energy transmitting module accordingly in traditional wireless home appliances,and improves the versatility of the system.The main research and results of this paper are as follows:(1)The theoretical model of the MCR-WPT system circuit is established,the four basic compensation circuits are compared,and the influence of the operating frequency,coil mutual inductance,load resistance and other factors on the system’s transmission power and efficiency are analyzed.The spatial distribution of the current-carrying coils is conducted based on microelement method,and the principle of active magnetic shielding is analyzed from the theoretical level,which lays a theoretical foundation for the design of Halbach coil.(2)The coupling mechanism based on Halbach effect is proposed,and its magnetic shielding principle is analyzed based on the equivalent magnetic circuit model of Halbach coil;The finite element model of Halbach coil is established,the influence of the number of turns of auxiliary coil on coil mutual inductance and target magnetic flux density is simulated,and the optimal parameters of Halbach coil are determined;The magnetic shielding performance of Halbach coil is simulated and analyzed.The results show that Halbach coil can effectively weaken the magnetic field around the coil compared with DD coil,and has obvious unilateral magnetic field shielding effect;High frequency inverter circuit,driving circuit and rectifier circuit are designed to meet the performance requirements of MCR-WPT system.(3)The mathematical models of different types of LC and DC-DC impedance matching networks are established,the parameters of various types of impedance matching networks are deduced and compared,and the Buck Boost converter is selected to build the impedance matching network of MCR-WPT system;Based on the Simulink circuit simulation model,the load compatibility of the system with and without impedance matching network is compared.The results show that when the impedance matching network based on Buck Boost converter is added,the system can maintain high energy transmission efficiency when the load changes in a wide range.When the load is 100 Ω,the energy transmission efficiency of the system with impedance matching network is 17.51% higher than that without impedance matching network,and the load compatibility is greatly improved.(4)The experimental platform of MCR-WPT system based on Halbach resonator is built,and the mutual inductance,energy transmission power and efficiency,anti offset performance and other parameters of Halbach coil are tested.The results show that under the optimal transmission state,the energy transmission power and efficiency of Halbach coil are 106.35 W and 82.85% respectively,which are about 4.91% and 0.34% higher than that of DD coil,and have certain anti offset ability.Halbach coil not only has better transmission performance than DD coil,but also has better magnetic shielding effect.The load compatibility of the system is tested based on the impedance matching experiment.The results show that adding the impedance matching network based on Buck Boost converter can greatly improve the load compatibility of the system,enable the system energy transmitting module to supply power to electrical equipment with different loads,and improve the universality of the system. |
