The emerging adoption of wide-bandgap semiconductor devices in motor-drive systems poses significant challenges to the stator winding dielectric insulation of electrical motors due to their high voltage slew rate. Such ultra-fast switching characteristics generate fast-rising voltage pulses with high $dv/dt$ , which may produce high-frequency (HF) overvoltage transients at the motor terminals. The reflected overvoltages result in a nonuniform voltage distribution along the motor stator windings, imposing excessive electrical stress on the winding insulation. Therefore, an HF model operating at the MHz scale, capable of accurately predicting reflected voltage stress across stator winding coils and turns, is essential for developing high-reliability motor-drive systems. This article proposes an HF modeling framework that integrates finite-element analysis with a distributed parameter network to improve the prediction accuracy of reflected voltage distributions. The proposed HF model incorporates frequency-dependent material characteristics, winding configurations, and interwinding coupling effects through systematic parameter extraction while maintaining moderate implementation complexity. A 2-hp induction motor prototype has been custom-rewound to experimentally verify the proposed HF model under multiple cable lengths and voltage pulse rise times. Experimental results demonstrate the superior performance of the proposed modeling approach compared to conventional methods, achieving time-domain reflected voltage estimation errors below 4%, while maintaining strong agreement with measured impedance spectra across a wide frequency range.
Mohamed Y. Metwly, Abdelrahman Habib, Yiju Wang et al.· IEEE Open Journal of Industr...· 0 citations
The rapid adoption of fast-switching wide bandgap (WBG) semiconductor devices in motor-drive systems has introduced significant benefits in achieving high efficiency and high power density but also posed challenges associated with reflected overvoltage phenomena. Such reflected overvoltages impose severe high-frequency voltage stress on motor stator windings, which accelerate insulation degradation and undermine the reliability of motor stator windings. Traditionally, RLC $dv/dt$ filters have been used as an effective mitigation technique for limiting voltage slew rates and protecting the motor winding against these reflected overvoltages. However, these filters introduce excessively additional losses, size, and weight to the overall motor-drive systems. In contrast, the recently proposed smart coil circuit (SCC) has emerged as an alternative mitigation technique. This new approach enables effective suppression of reflected overvoltages with ultrahigh efficiency through its adaptive, ultracompact, and self-powered design. This article presents a comparative study of the smart coil mitigation technique versus the conventional RLC $dv/dt$ filter for overvoltage mitigation. The comparison focuses on operating efficiency, the effectiveness of mitigating overvoltage stress on motor stator windings, and identifying which mitigation technique is more effective for various operating conditions. Finally, comparative experimental validations based on a 2-hp motor-drive system demonstrate the effectiveness of both mitigation methods and provide an assessment of their strengths and limitations in WBG-based motor-drive systems.
Abdelrahman Habib, Mohamed Y. Metwly, Jiangbiao He· IEEE Journal of Emerging and...· 1 citation
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