Research On Magnetically Coupled Resonant Wireless Power Transmission System Based On PCB Fractal Coil

With the popularization of electronic products,the charging technology is also developing rapidly,and the traditional charging methods are prone to aging and bring security risks.Wireless energy transmission technology belongs to non-contact energy transmission,which has the advantages of safety and convenience.Coils,magnetic cores and metal shields constitute the coupling mechanism in the wireless power transmission system.The coupling mechanism in the magnetic coupling resonance wireless power transmission system is called the magnetic coupling mechanism.In order to reduce the requirement of alignment accuracy in the process of wireless charging of low-power devices,it is very important to study the offset resistance of the coupling mechanism.A coupling mechanism with better offset resistance can improve the stability of the power picked up by the device.Firstly,the magnetic coupling mechanism in the wireless power transmission system is theoretically analyzed,and the Koch snowflake coil in the fractal coil is proposed as the energy transfer coil of the wireless power transmission system,and the shape and magnetic core structure of the Koch snowflake coil are optimized.Using Maxwell simulation software,the anti-offset performance of the Koch coil(Koch coil)and the planar circular coil are compared in the following four cases: offset on the X axis or Y axis;offset on the XOY plane;on the Z axis Up offset;rotation offset around the Z axis.It is known that the offset resistance of the Koch coil is better than that of the circular coil within a certain range.As the offset distance continues to increase,the offset resistance of the two tends to be consistent.Then the magnetic coupling resonant wireless power transfer system is analyzed.The four resonance compensation methods are compared and studied,and the parallel-parallel compensation topology is selected as the resonance compensation topology of the system according to the objects and application scenarios.Theoretical derivation is made for the parallel-parallel compensation wireless power transmission system,and the parameters of each component are calculated.The system model was built by MATLAB/Simulink simulation software,and the output efficiency and output power of the two coils in the same system were compared.It is found that the output efficiency and output power of the transmission system based on the Koch coil are slightly better than the transmission system based on the circular coil.Finally,build the experimental platform.On the basis of theoretical analysis,hardware circuit design,including inverter circuit,control unit,drive circuit and rectifier filter circuit,is carried out to verify the correctness of theory and simulation.Under the condition that the input voltage is 12 V,the output power of the system is not less than 15 W and the transmission efficiency is not less than 80% when the Koch coil is facing directly.