High-Frequency Modeling of Bearing and Transmission Currents in Electric Vehicles

International Conference on Electrical Machines (ICEM), pp. 1–6

Abstract

The pulse-width modulation employed in inverters generates a common mode voltage, leading to bearing currents that can reduce the lifetime of electrical machines. The automotive industry's trends towards higher battery voltages and fast-switching wide-bandgap semiconductor devices further exacerbate this phenomenon. This study presents an extended high-frequency model of electric vehicle powertrains, parameterized analytically and numerically, which incorporates the transmission to predict parasitic current flow through all bearings and gears. The results indicate significant circulating bearing currents in electric vehicles with 800 V battery voltages and state-of-the-art inverters using wide-bandgap semiconductor devices. Furthermore, it is shown that the installation of a shaft grounding device on the drive end of electrical machines, coupled with the inclusion of a transmission, yields a significant reduction in drive end bearing currents while showing no substantial impact on the non-drive end bearing current. The observed transmission bearing currents and current densities indicate a low risk of bearing damage.

Authors 3

1. Yusa Tombul Aachen

   RWTH Aachen University

   Affiliation as printed

   Teaching and Research Area Mechatronics in Mobile Propulsion, RWTH Aachen University,Aachen,Germany,52074

2. Jian Zhang Aachen

   RWTH Aachen University

   Affiliation as printed

   Teaching and Research Area Mechatronics in Mobile Propulsion, RWTH Aachen University,Aachen,Germany,52074

3. Jakob Andert Aachen

   RWTH Aachen University

   Affiliation as printed

   Teaching and Research Area Mechatronics in Mobile Propulsion, RWTH Aachen University,Aachen,Germany,52074