Abstract: Broadband and high-amplitude electromagnetic interference exists in the working process of an electric drive system，posing a significant threat to the system itself and other electronic and electrical equipment. This paper proposes an innovative method for modeling the three-phase synchronous motor while taking the parasitic effect of interference into consideration. The method can help researchers analyze EMI risks and improve the system.First，the frequency domain characteristics of the common-mode and differential-mode impedance of the motor's three-phase port are obtained upon tests.Then，the characteristics of the single-phase common-mode and differential-mode impedance of the motor are obtained upon mathematical derivation，and high-frequency equivalent circuit models of the single-phase port of the motor are developed through vector fitting. Finally，a complete three-phase circuit model of the motor is constructed based on star connection of single-phase equivalent circuits. Based on this method，an equivalent model of a 140 kW permanent magnet synchronous motor is built，and the accuracy of the model is validated by tests.Results show that this method is compatible with a wide frequency range and has good convergence and high accuracy，and can be cascaded with other electronic and electrical modules to form a complete electric drive system model.The innovative and practical approach can effectively support fast analysis and prediction of system-level EMI and electromagnetic sensitivity.

Key words: armoredvehicle, electromagneticcompatibility, three-phasesynchronousmotor, electricdrivesystem, high-frequencyequivalentcircuitmodel