High-Frequency Modeling and Sensitivity Evaluation of Motor Terminal Overvoltage in Long-Cable PMSM Variable Frequency Drive Systems

Long-distance variable frequency drive (VFD) systems are widely used in mining and water transport applications, yet motor terminal overvoltage remains a major reliability risk when inverters and motors are separated by long cables. This study examines a mining submersible pump permanent magnet synchronous motor (PMSM) drive. Cable distributed parameters were extracted with Ansys Q2D Extractor, and a wideband simulation model was built in MATLAB/Simulink. To ensure modeling accuracy, the wideband transmission line model was calibrated and validated using a 20 m cable VFD experimental platform, demonstrating an excellent agreement with a peak voltage relative error of only 2.56%. Parametric simulations were used to quantify the effects of cable length, pulse width modulation (PWM) pulse rise time, and cable cross-sectional geometry on normalized motor terminal overvoltage. Cable length and pulse rise time were the dominant factors governing overvoltage severity. Minor changes in conductor radius or spacing produced only limited changes in peak overvoltage. These findings support EMC-oriented design priorities for long-line VFD systems, with emphasis on cable routing and inverter dv/dt coordination rather than fine cable-geometry tuning alone.