Analysis And Design Of Inductively Coupled Power Transfer System For LCL Compensation

Inductively coupled power transfer(ICPT)technology is an emerging technology that realizes non-contact power transmission based on the near field coupling principle of high frequency electromagnetic field.The transmission process includes high-frequency inverter,resonant compensation network and loosely coupled transformers.It exhibits multi-parameter and high-order nonlinear characteristics,and then the system's parameters changes can have a significant impact on transmission performance.Therefore,by analyzing the relation among parameters,and then get the circuit parameter design method has important significance and valuable reference to improve the system's transmission performance.By analyzing the impedance transformation and output characteristics of the LCL resonant circuit,a resonant frequency calculation method for achieving steady current-steady voltage was obtained.The basic working process of the full-bridge LCL resonant ICPT system was analyzed,based on the mutual inductance equivalent model,the expression of the system output voltage was deduced.The simulation analysis was performed using Matlab,and the curve of the load resistance effect and frequency on the output voltage was obtained.By analyzing the factors that affect the power transfer capability of LCL compensation system,the relationship between coupling coefficient k,inductance ratio ?,quality factor Qn and transfer power is obtained,which provides a theoretical basis for the system parameter selection.In the case of different quality factors,by analyzing the stress of the resonant element near the resonant frequency,it is concluded that when the system transmits the same power,the switching device of the LCL type compensated ICPT system suffers lower current stress and the system reliability is higher.Taking into account the internal resistance of the coil,the expression of the system efficiency is derived,and the relationship between the mutual inductance,operating frequency,load resistance and system efficiency and the optimum resonant frequency corresponding to the maximum efficiency of the system are obtained.By analyzing the curve relationship between the active power and the load of the primary resonant network port,the rated output power of the system corresponding to the optimal inductance ratio of the LCL compensation circuit is obtained.According to analyze the relationship among various parameters,the key parameter design of resonant frequency,inductance radio,resonant coil and compensation capacitor are designed,a full-bridge LCL compensation ICPT system parameter design method is proposed.This design method can insure the system works in the best state and energy high-efficiency transmission by selecting parameters combination.A LCL full-bridge ICPT prototype and the experimental platform was established.The system key parameters were tested and analyzed,and the theoretical analysis and the feasibility correctness of the design method were verified through the experimental results.