Moving Toward a Reliability-Oriented Design Approach of Low-Voltage Electrical Machines by Including Insulation Thermal Aging Considerations

Abstract

Electrical machines (EMs) are required to consistently perform their intended mission over a specified timeframe. The move toward transportation electrification made the EMs' reliability an even stringent and predominant requirement, since a failure might cause severe economic losses, as well as endanger human lives. Traditionally, the design procedure of motors conceived for safety-critical applications mainly relies on over-engineering approaches. However, a paradigm shift is recently taking place and physics of failure approaches/methodologies are employed to meet the reliability figures, while delivering an optimal design. This article proposes and outlines a reliability-oriented design for low-voltage EMs. Thermal accelerated aging tests are preliminarily carried out on custom-built specimens. Once the aging trend of the turn-to-turn insulation system is assessed, the thermal endurance graph at several percentile values is determined and lifetime models are developed, for both constant and variable temperature operations. Finally, these models are used to predict the turn-to-turn insulation lifetime of motors meant for aerospace and automotive applications.