A nonlinear model of choke transformer considering core saturation

CUI Yong; YANG Xiaofan; XIE Luyu

doi:10.11860/j.issn.1673-0291.20220017

Abstract：To address the magnetic core saturation caused by unbalanced traction currents in 25 Hz phase-sensitive track circuits,a modeling method for the nonlinear model of a choke transformer is proposed.The approach combines the JA(Jiles-Atherton)hysteresis model and the three-capacitor transformer model.Firstly,a JA hysteresis model parameter identification algorithm based on Particle Swarm Optimization(PSO)is designed.This algorithm,along with the energy calculation method,is utilized to extract the JA hysteresis loop parameters of the iron core and the distribution parameters in the nonlinear model of the choke transformer,respectively.Subsequently,by comparing the calcu-lated distribution parameters with Maxwell's simulation results,it is concluded that the parameters,such as leakage inductance and distributed capacitance of the choke transformer,extracted by our method exhibit good accuracy.Finally,the results of solving the BH curve,excitation current,and output voltage curves of the nonlinear choke transformer model are compared and verified against Pspice simulation results.The research results indicate that the proposed model can be utilized to accu-rately analyze the saturation problem of magnetic cores in choke transformers.The saturation state of the magnetic core can be determined by analyzing the real-time hysteresis loop shape of the model core or the distortion of the primary current in the choke transformer.