Comparative Analysis between Measured and Simulated Pulse Voltage Distribution in Form Wound Stator Winding of Inverter-Fed Motors

This paper presents a simulation study of a pulse voltage distribution within the windings of a motor using a high-frequency (HF) equivalent circuit model. The simulation results are validated by comparison with measured data, aimed at enhancing insulation design technology for next-generation inverter-fed motors. The investigation focuses on pulse voltage propagation between each coil-to-ground and turn-to-turn in the initial winding, which is crucial for selecting the optimal insulation design for evaluation. The subject of this study is an inverter-fed three-phase induction motor with a rated output of 75 kW and a rated voltage of 3kV<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</inf>. The winding configuration consists of two parallel wound types with 10 turns and 16 windings per phase, featuring 4 poles. The impulse voltage used had a rise time of 250 ns, a pulse width of 50μs, and a voltage amplitude of 1000 V. An impulse voltage was applied from the beginning to the end of Phase U, and output waveforms at each measurement point were obtained. Additionally, the output voltage waveforms for each turn were simulated using the developed HF equivalent circuit model, implemented in LTspice® (Analog Devices), a transient phenomenon simulation software, and compared with the measured results. The simulated results show good agreement with the measured results. The maximum simulated voltages matched measured values within an error margin of less than 3.7<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> for coil-to-ground and 9.5% for turn-to-turn in the initial winding. The developed HF equivalent circuit model is validated as a useful tool for evaluating surge voltage impacts in the insulation design of stator windings.