The Electrical Modeling of Machine Elements

verfasst von

Volker Schneider

betreut von

Gerhard Poll

Abstract

The predictability of the electrical properties of machine elements is crucial for the reliability of modern electrified powertrains. Despite existing knowledge, there are significant gaps in electrical modeling to understand the complex relationships between mechanical and electrical loads. This work aims to develop simple analytical methods for determining the electrical properties of machine elements.

Additionally, the impact of current passage on the service life of rolling bearings is unknown and is comprehensively investigated through various experimental studies in this work. By modifying hybrid bearings with different numbers of steel rolling elements, insights have been gained into pre-damages and the effects of current passage. Experiments focusing on single steel rolling elements have highlighted the impact of loaded zones and lubricant film thickness on current passage, revealing breakdowns and arcing phenomena. Microscopic analysis of damaged raceways has identified mechanisms such as vaporized craters that alter surface roughness. Service life tests have uncovered failure mechanisms distinct from classical rolling contact fatigue, providing crucial insights into the consequences of electrical damage. Weibull analysis has revealed varied experimental life spans, underscoring the significant influence of electrical damage on bearing reliability.

In parallel, models have been developed to determine the electrical properties of rolling bearings and gears. A simulation-based film thickness-dependent correction factor, validated through comprehensive experiments, has enhanced the accuracy of calculating electrical capacitance. This factor, previously assumed constant, is critical for the design of electric drive trains. Models initially developed for point contacts have been successfully extended to line contacts, applicable to raceway-roller contacts in cylindrical and tapered roller bearings, with an initial adaptation to transient conditions in gear contacts.

These advancements have facilitated more accurate estimations of bearing capacitance, improving the anticipation of critical conditions and electrical stresses in electric drives. The models also improve impedance calculations, enabling more precise predictions of the resistive component of the EHL contact caused by the lubricant.

Organisationseinheit(en)

Institut für Maschinenkonstruktion und Tribologie

Typ

Dissertation

Publikationsdatum

2025

Publikationsstatus

Veröffentlicht

Elektronische Version(en)

https://doi.org/10.15488/18308 (Zugang: Offen)