Wireless Power Transfer Closed Loop Control And System Design For Lithium Batteries

Compared to traditional wired charging methods for lithium batteries,wireless power transfer(WPT)technology has better flexibility and security,and can adapt to more complex external environments.In recent years,it has been widely used and developed in various fields.However,WPT systems are susceptible to external interference and self parameter disturbances,resulting in difficult output voltage and current control and unstable output power.To solve the above problems,this paper proposes a WPT system with constant current and constant voltage two-stage closed-loop output.Firstly,based on the magnetically coupled resonant WPT system,this article introduces its basic structure and working principle,compares and analyzes the output characteristics of four traditional single resonant networks through circuit modeling,and analyzes the transmission characteristics of LCC-S higher-order resonant networks.Through formula derivation and simulation analysis,it is determined that the higher-order resonant network has the output characteristics of constant current on the primary side and constant voltage on the secondary side and has a high degree of design freedom.Based on this,aiming at the impact of load and mutual inductance disturbances on the system output,a two-stage closed-loop control strategy with constant current and constant voltage on the secondary side based on a PI controller is designed,and the shortcomings of this control method are described.Then,in order to further improve the robustness and dynamic adjustment ability of the WPT system,the application of Active Disturbance Rejection Control(ADRC)to the WPT system is proposed based on the characteristics of nonlinearity,time-varying,and uncertainty of the WPT system.The disturbance analysis is performed through system modeling and an ADRC controller is designed based on the model.At the same time,in order to improve the performance of ADRC controller,particle swarm optimization(PSO)algorithm is used to optimize the controller parameters.Simulation results show that the system achieves constant current and constant voltage two-stage closed-loop output under multi-parameter disturbances,which has significant advantages over PI controllers.Finally,according to the WPT system design scheme,the hardware circuits of each part of the system are designed,including the coupling coil,LCC-S resonant network,high-frequency inverter circuit,high-frequency rectifier circuit,and Buck circuit.The software control programs for the primary and secondary sides of the system are designed based on the TMS320F28335 control chip.The experimental results show that the designed WPT experimental platform has magnetic coupling resonance characteristics,with a maximum transmission efficiency of 90%.The proposed constant current and constant voltage two-stage closed-loop control strategy for WPT systems based on ADRC has the characteristics of fast dynamic response and strong robustness,which verifies the correctness of the theoretical analysis and simulation results in this paper.