Efficiency Optimization And Signal Transmission Of Wireless Power Transmission System Based On Phase-controlled Switched Capacitors

Wireless power transfer(WPT)technology has gained widespread attention and preliminary application in recent years in the fields of consumer electronics,electric vehicles,medical electronics,etc.due to the characteristics of non-contact power transmission.With the rapid development of WPT technology,how to improve the efficiency of power transmission has become a major factor restricting the rapid development and wide application of this technology.Generally,the capacitance and inductance in the primary side of a wireless power transmission(WPT)system need to be properly designed and precisely adjusted to make sure the system operating in resonance.For this reason,a novel Autonomous Impedance Adaptation(AIA)strategy is proposed in this paper.This strategy uses Phase-Controlled Switched Capacitors(PCSCap)to achieve adaptive impedance matching of WPT systems to increase power transmission efficiency.First,this paper uses the complex ? plane to quantitatively analyze and establish the correspondence between the input impedance characteristic value and resonance.Then by capturing the input impedance angle for feedback control,the equivalent capacitance of PCSCap is adaptively adjusted,so that the WPT system always works in the resonance,thereby maximizing its transmission efficiency.The AIA strategy proposed in this paper has both high impedance adjustment accuracy and large self-recovery margin.Finally,the effectiveness and advantages of the proposed AIA mechanism based on PCSCap are proved through simulation and experiments,showing its great practicality and wide applicability in the industry.Aiming at the influence of the change of the compensation capacitor on the harmonic content of the system,through theoretical analysis and simulation,the relationship between the third harmonic content of the system and the compensation capacitor is found,and a compensation fault diagnosis method based on the third harmonic detection is proposed.On this basis,by analyzing the advantages of phase-controlled capacitors in terms of modulated signals,the application of phase-controlled capacitors in signal transmission of WPT systems has been expanded.The phase-controlled capacitor is used to change the resonance frequency of the resonant tank,and a signal frequency different from the switching frequency is modulated for signal transmission.The optimal transmission frequency is found by performing frequency-scanning simulations.At the optimal transmission frequency,the discrete-fourier decomposition of the secondary-side output voltage is performed by software programming,and the ratio of the amplitude of the signal frequency component to the amplitude of the fundamental frequency component is found as the signal symbol decision condition.The signal demodulation results show that the phase-controlled capacitor modulation method can perform signal transmission.The finite element simulation platform ANSYS was used to build a 3D model of the transmission coils,through finite element analysis and eddy current field simulation.On the Electronics Desktop platform of ANSYS,Simplorer and Maxwell co-simulation were used to solve the main circuit parameters and transmission coil parameters that met the output voltage and output power requirements.Based on the results of the finite element simulation,a small high-voltage line energy extraction device was built based on wireless power transmission with a rated output of 100 W.