Physics of failure as a technology enabler for electrical machines in transportation: reliability-oriented design of low voltage insulation systems

Madonna, Vincenzo (2020) Physics of failure as a technology enabler for electrical machines in transportation: reliability-oriented design of low voltage insulation systems. PhD thesis, University of Nottingham.

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In modern electrical machines there is an-ever-increasing push towards high power density and efficiency, which are thus considered as main design objectives. On the other hand, electrical machines used in certain applications, such as in the transport industry, are also required to be highly reliable and robust. In order to achieve the much needed power density performances, “extra” stresses are being experienced by the insulation systems of these machines, often resulting in accelerated components degradation and compromised system-level reliability figures. In general, the lifetime consumption evaluation and the reliability assessment of electrical machines components, including the insulation system, are still evaluated through outdated methods. These are often based on historical data and adopt constant failure rates, derived by statistically post-processing the failure times of a large number of built prototypes. This is of course a very time-consuming and expensive process. In application fields such as automotive and aerospace, the reliability assessment procedures can then negatively affect the development timeline of an electrical product, especially for certification.

This Thesis therefore argues for the development of new processes, based on comprehensive physics of failure methodologies, for assessing the lifetime consumption and degradation of insulation systems for electrical machines. This will enable the electrical machine designer to make reliability considerations a main design objective, right from the very start of the design process. As a result of this work, this Thesis also shows how the proposed advanced philosophy will allow manufacturers to design insulation systems without relying on outdated, traditional “safety factors” and over-engineering concepts.

The proposed processes focus on the development of new lifetime prediction models for electrical machines. The core of the Thesis is focused on thermal considerations and stresses. The novel models, developed in this work, seek to achieve significant improvements in terms of accuracy of lifetime prediction, by combining the cumulative damage law with the conventional Arrhenius model. The Thesis also includes considerations on partial discharges and ensuing insulation electrical stresses.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Galea, Michael
Giangrande, Paolo
Gerada, Christopher
Keywords: Electrical Machines, Reliability, Thermal Analysis, Physics of Failure, Insulation Systems, Thermal Aging, Partial Discharges, Design of Experiments
Subjects: T Technology > TJ Mechanical engineering and machinery
Faculties/Schools: UK Campuses > Faculty of Engineering > Department of Electrical and Electronic Engineering
Item ID: 60441
Depositing User: Madonna, Vincenzo
Date Deposited: 31 Jul 2020 04:40
Last Modified: 31 Jan 2023 09:24

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