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The increasing interest in employing wide-bandgap (WBG) drive systems has brought about very high power, high-frequency inverters enjoying switching frequencies up to hundreds of kilohertz. However, voltage surges with steep fronts, caused by turning semiconductor switches on/off in inverters, travel through the cable and are reflected at interfaces due to impedance mismatches, giving rise to overvoltages at motor terminals and in motor windings. The phenomena typically associated with these repetitive overvoltages are partial discharges and heating in the insulation system, both of which contribute to insulation system degradation and may lead to premature failures. In this article, taking the mentioned challenges into account, the repetitive transient overvoltage phenomenon in WBG drive systems is evaluated at motor terminals and in motor windings by implementing a precise multiconductor transmission line (MCTL) model in the time domain considering skin and proximity effects. In this regard, first, a finite element method (FEM) analysis is conducted in COMSOL Multiphysics to calculate parasitic elements of the motor; next, the vector fitting approach is employed to properly account for the frequency dependency of calculated elements, and, finally, the model is developed in EMTP-RV to assess the transient overvoltages at motor terminals and in motor windings. As shown, the harshest situation occurs in turns closer to motor terminals and/or turns closer to the neutral point depending on whether the neutral point is grounded or floating, how different phases are connected, and how motor phases are excited by pulse width modulation (PWM) voltages.
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This content will become publicly available on March 1, 2026
Influence of Wideband Cable Model for Electric Vehicle Inverter–Motor Connections: A Comparative Analysis
Electric vehicles (EVs) rely on robust inverter-to-motor connections to ensure high-efficiency operation under the challenging conditions imposed by wide-bandgap (WBG) semiconductors. High switching frequencies and steep voltage rise times in WBG inverters lead to repetitive transient overvoltages, causing insulation degradation and premature motor winding failure. This study proposes a wideband (WB) model of EV cables, developed in EMTP-RV, to improve transient voltage prediction accuracy compared to the traditional constant parameter (CP) model. Using a commercially available EV-dedicated cable, the WB model incorporates frequency-dependent parasitic effects calculated through the vector fitting technique. The motor design is supported by COMSOL Multiphysics and MATLAB 2023 simulations, leveraging the multi-conductor transmission line (MCTL) model for validation. Using practical data from the Toyota Prius 2010 model, including cable length, motor specifications, and power ratings, transient overvoltages generated by high-frequency inverters are studied. The proposed model demonstrates improved alignment with real-world scenarios, providing valuable insights into optimizing insulation systems for EV applications.
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- Award ID(s):
- 2306093
- PAR ID:
- 10652894
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Machines
- Volume:
- 13
- Issue:
- 3
- ISSN:
- 2075-1702
- Page Range / eLocation ID:
- 189
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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