Research On AC-AC Wireless Power Transfer System Based On Impedance Matching

Wireless Power Transmission(WPT)technology is to transfer electric energy from the power supply end to the electrical equipment by means of space media such as electric field or magnetic field,so as to realize the wireless transmission of electric energy.Compared with the traditional way of using cables to transmit electric energy,this transmission method is safer,more convenient and reliable,and the use of electrical equipment has greater flexibility and wider environmental adaptability.It has been widely used in new energy vehicles,Human implantable medical equipment and underwater robots and other fields.However,most of the current research on WPT systems is for DC loads such as batteries,and few scholars have studied the AC output of WPT systems.Therefore,the research on the WPT system with AC-AC conversion has a very high application prospect and research to value.In view of the above problems,this paper studies the AC-AC envelope modulation WPT system,and uses mathematical modeling to deduce and calculate the system output.Since the system output is AC voltage,while paying attention to the system transmission power and efficiency,the Total Harmonic Distortion(THD)of the system output AC is also calculated and analyzed,and a system impedance parameter matching method is proposed.Finally,an experimental platform is built to verify the theoretical analysis.The main work of this paper are as follows:First,the basic structure and working principle of the WPT system is introduced,and the output expressions of four classic compensation network topologies and commonly used composite compensation network topologies are derived from mathematical modeling,and the constant voltage and constant current output characteristics of each network are analyzed and pros and cons.And briefly analyzed the topological structures of several common ACAC conversion WPT systems.Secondly,this paper uses the time-domain analysis method to mathematically deduce and calculate the AC-AC envelope modulation WPT system,and obtains the system output power and efficiency expressions.The influence of system parameters on the output voltage is analyzed,including diode voltage dropped,input AC voltage amplitude,system switching frequency,and system damping state changes caused by loads,and two types of system envelope voltage zero-crossing and valley elevation are analyzed.The Total Harmonic Distortion of the output voltage of the system is calculated and analyzed.Then,a system parameter matching method is proposed to analysis and calculation.Under the conditions of constant system input voltage and switching frequency,the optimal selection range of system parameters is proposed,and the impedance matching network topology is introduced into the system to change the damping state of the system.Combined with MATLAB/Simulink simulation software to model and simulate the system,the correctness and feasibility of the proposed method is verified.Finally,according to the system parameter requirements,the hardware structure design and device selection of each module of the system are carried out,and the experimental platform of the AC-AC envelope modulation WPT system is built.In the case of changing the voltage input amplitude,system switching frequency and load size,the system output is tested experimentally,and the feasibility of the system and the correctness of the proposed system parameter matching method are verified by the experimental results.