Fatigue life prediction of Electric RaceAbout (ERA) traction motor rotor

The automotive industry has been making a strong shift toward electrically powered vehicles lately. Electric traction motors, needed for such an application, should have high power density, high efficiency and last but not least, a reliability. The permanent magnet synchronous motor (PMSM), was originally designed as a traction motor for a full electric sports car Electric RaceAbout (ERA). Reliability assessment of such motor was investigated by performing fatigue life analysis over load-cycle. To perform rotor fatigue life estimation of PMSM in dynamic conditions, a multidisciplinary approach is needed, combining stresses caused by centrifugal forces, tangential forces caused by torque, as well as thermal stresses due to electromagnetic losses. In this paper, fatigue life of PMSM rotor is estimated according to stress-based approach with mean stress correction and variable amplitude loading obtained from transient thermal - structural FE analysis. Loads in analysis, were defined based on the measurements performed on electric sports car and electromagnetic analysis of losses in permanent magnets and rotor lamination. Variable equivalent stress amplitudes were identified with rainflow counting technique for time history of equivalent stresses for critical rotor position. Stress amplitudes were then corrected with three mean stress correction models, namely, modified Goodman, Morrow and Smith-Watson -Topper (SWT) and compared with modified S-N curve. Total damage was finally calculated according to Palmgren-Miner rule. (C) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID 2020 Organizers.