Multi-Frequency Multi-Load Magnetically Coupled Resonant Wireless Power Transfer System

In recent years,wireless power transfer(WPT)technology has attracted more and more attention because of its convenience,safety and green performance.Among them,Magnetic Coupling Resonant Wireless Power Transfer(MCR-WPT)has become the most mature and widely used WPT technology due to its high transmission efficiency,high output power and immunity to space non-magnetic obstacles in medium distance scenarios.With the increasing demand for multi-electrical equipment access to MCRWPT system,the research mode has gradually changed from " one-to-one " to " oneto-many".The coupling degree between the parameters of the multi-load system is strong,and the change of mutual inductance and load parameters will seriously affect the output characteristics of the system.At the same time,the uncertainty of mutual inductance and load parameters makes the system controller design complicated.In order to provide a stable and efficient energy transmission system,it is necessary to identify the mutual inductance and load parameters.Based on the single-inverter singletransmitting and multi-receiving MCR-WPT system,this thesis proposes a parameter identification method suitable for multi-load systems.By selecting the particle swarm optimization algorithm as the parameter identification algorithm,the primary voltage and current information are sampled to realize the multi-load system.Synchronous identification of multi-mutual inductance and multi-load lays the foundation for designing a stable and efficient multi-load system control strategy.The main research contents are as follows:Firstly,the research background,research status,research purpose and significance of WPT system parameter identification technology are introduced.Secondly,the topology of multi-frequency and multi-load MCR-WPT system is analyzed.Taking the dual-frequency and dual-load system as an example,the system is modeled and analyzed based on the circuit theory.The mathematical model of the system output efficiency about the mutual inductance of the coupling coil and the load is established,and the influence of the two parameters on the output characteristics of the system is further analyzed,which lays a theoretical foundation for the design of the subsequent system parameter identification.Secondly,the input impedance of the system at each frequency is analyzed,and the equivalent single-load MCR-WPT system and multi-load MCR-WPT system mutual inductance identification model with respect to load parameters are established.Then,the sliding window discrete Fourier transform(SDFT)is designed to realize the frequency division extraction of the primary side mixing current according to each frequency component,so as to meet the sampling of the inverter output current at each frequency in the parameter identification process.After that,the particle swarm identification module is designed,and the simulation model of parameter identification model is built and verified in MATLAB / Simulink environment.Finally,the experimental platform of dual-frequency power supply input system is built to verify the identification of load and mutual inductance parameters.The experimental results show that the maximum relative error of load identification is less than 7%,and the maximum relative error of mutual inductance identification is less than 6%.The identification value is basically consistent with the actual value,which proves the effectiveness of the proposed identification model and identification algorithm.