Research On Medium And Small Power Induction Coupled Resonant Wireless Charging Device

Medium and small power inductively coupled resonant wireless charging devices provide the required power for the electrical equipment by a non-contact mode,it has wide application whether in the household appliances or in the electric vehicle charging.Compared to the wired power supply,it is more secure and convenient.In this thesis,the voltage and current relationships of the various components under normal operating conditions are analyzed for LCL topology,which is widely used in wireless charging,and the relationship between voltage and current of three components under different operating conditions is analyzed.Combining the expressions of the parallel compensation capacitance voltage phasors on both sides under different operating conditions,the similarities and differences of the component voltage values in the above-mentioned cases are given,which are used for the follow-up voltage detection and protection.Then analyze the factors affecting the transmission efficiency of the power coil of the loosely coupled transformer,and obtain the expressing of the coil transmission efficiency with the mutual inductance ratio of the power coil,finally,draw the curve of the change of the resistance ratio with the efficiency above 90%.According to the expression of transmission power of loosely coupled transformers,the four factors affecting the transmission power are analyzed.The optimal size of the coil under a given transmission power and efficiency is predicted by the self-inductance theory of the hollow-loosely coupled transformer.Compare the square and double D shaped coil at different distances under different lateral displacement characteristics,and measure the two coils AC impedance with frequency of the relationship.According to the above theoretical analysis,the design idea of the medium and small power inductive coupling resonator wireless charging device is given.Finally,according to the results of theoretic analysis,designed to meet the needs of the loosely coupled transformer.According to the penetration depth,the single conductor wire diameter of the transformer conductor is selected reasonably.The voltage and current peak value of each element of the resonant circuit is calculated theoretically,and the high frequency inverter circuit,the voltage and current detection circuit,the switch driver circuit and the high frequency rectification circuit are designed.Finally,Set up the 3700W radio transmission system platform and experiment on the efficiency of different power output of the inverter,when the input voltage of the inverter is 400V,the output voltage is 300V,the transmission distance is 20cm,and the load is 25Ω,there is no lateral offset,the overall efficiency of the device reaches 91.25%.