Under pulse-width modulation (PWM) voltage excitation

the transient voltage distribution in stator windings of inverter-fed motors is influenced by nonlinear coupling effects of distributed capacitance and leakage inductance parameters. Structural discontinuities in windings tend to induce electric field distortions due to high-frequency transient effects

significantly increasing the probability of partial discharges in dielectric materials. Accurate characterization of the spatial distribution characteristics of transient electrical stress under pulsed voltage excitation constitutes a critical technical challenge for reliability design and lifetime assessment of insulation systems in inverter-fed motors. This study focuses on a 230 kW-class marine propulsion motor with lap-wound configuration. Based on electromagnetic multiphysics coupling theory

a two-dimensional electrostatic field model is employed to analyze lumped capacitance parameters of slot-embedded conductors

while a three-dimensional eddy current field model is utilized to extract frequency-dependent impedance characteristics of overhang regions. Through field-circuit co-simulation

a comprehensive multi-node equivalent circuit model of the stator winding path is established. To validate the electromagnetic transient response accuracy of the model

an independently developed pulse power supply test platform with wide-frequency bandwidth and high-power output capability (10 kV/100 A) was prepared. Comparative verification was conducted under following typical operating conditions: pulse voltage amplitude 1 kV

frequency 2.5 kHz

duty cycle 1%

and rise time 200 ns. The research results demonstrate: The relative error between simulated and experimental data remains below 12%

meeting engineering accuracy requirements; The first-turn conductor exhibits pronounced gradient distribution characteristics

with turn-to-ground and turn-to-turn potential differences reaching 117.3% and 13.56% of the applied voltage

respectively. The proposed 2D/3D multi-scale electromagnetic field modeling methodology effectively elucidates spatial gradient distribution patterns of electrical stresses in lap-wound configurations

providing both theoretical foundations and quantitative data supports for critical design optimizations including insulation thickness determination and voltage grading system implementation in inverter-fed motor applications.