All-Inorganic Electrical Insulation Systems for High-Power Density Electrical Machines

Kudrynskyi, Zakhar; Connor, Peter H.; Cooper, Timothy P.; Wadge, Matthew D.; Kerfoot, James; Zheng, Xiang; Felfel, Reda; Korolkov, Vladimir; Kubal, Martin; Gerada, Christopher; Grant, David M.

Abstract

This paper introduces the concept of ‘All-Inorganic Electrical Insulation (EI) System’ to enable the next generation of high-power-density electrical machines (EMs) that can operate at extreme conditions, namely high voltages (V) up to 1 kV DC and high temperatures (T) up to 500°C. The feasibility was explored for this concept using experiments and simulations by investigating the inorganic materials adapted to design high-T and high-V EMs. Candidate materials are (i) developed for magnet wire insulation and (ii) selected for a slot filler. In particular, employing physical vapor deposition (PVD), aluminum nitride (AlN) ceramic thin-film coatings were developed on Cu conductors. The experimental results demonstrate very high dielectric breakdown field strength (1 kV/micron for > 90 nm coatings) and thermal conductivity (290 W/m·K at room T (RT), 160 W/m·K at T=300 ∘C ), surpassing existing thin-film insulating materials. Thermal simulations using MotorCAD software compare conventional organic insulation of magnet wires with the AlN coatings. The AlN insulation alone potentially reduces operating T by 6 °C, enhancing EM efficiency. Combining AlN coatings with a selected high thermal conductivity slot filler at 500 °C enables fivefold heat dissipation, boosting potential power density by 50%. These findings demonstrate the potential of all-inorganic EI systems to deliver a step change in high-T EM design for aerospace, traction, and nuclear applications.

Citation

Kudrynskyi, Z., Connor, P. H., Cooper, T. P., Wadge, M. D., Kerfoot, J., Zheng, X., Felfel, R., Korolkov, V., Kubal, M., Gerada, C., & Grant, D. M. (2024, June). All-Inorganic Electrical Insulation Systems for High-Power Density Electrical Machines. Presented at 2024 IEEE 5th International Conference on Dielectrics (ICD), Toulouse, France

• Presentation Conference Type: Edited Proceedings
• Conference Name: 2024 IEEE 5th International Conference on Dielectrics (ICD)
• Start Date: Jun 30, 2024
• End Date: Jul 4, 2024
• Acceptance Date: May 30, 2024
• Online Publication Date: Aug 12, 2024
• Publication Date: Aug 12, 2024
• Deposit Date: Oct 10, 2024
• Publicly Available Date: Oct 31, 2024
• Publisher: Institute of Electrical and Electronics Engineers
• Peer Reviewed: Peer Reviewed
• Series ISSN: 2834-8311
• Book Title: Proceedings of the 2024 IEEE 5th International Conference on Dielectrics
• ISBN: 9798350308983
• DOI: https://doi.org/10.1109/ICD59037.2024.10613279
• Keywords: Power system measurements , Electric potential , Density measurement , Conductivity , Motors , Coatings , Wire
• Public URL: https://nottingham-repository.worktribe.com/output/40563239
• Publisher URL: https://ieeexplore.ieee.org/document/10613279