Welcome to PhD dissertation with Meng-Ju Hsieh

Title: Electromagnetic Modeling based Life Cycle Assessment of Rare-Earth-Free Propulsion Electric Machines for Vehicles

Venue: Division of Electric Power Engineering, Chalmers University of Technology, Room EA, Hörsalsvägen 11, Chalmers, Göteborg

Online: https://chalmers.zoom.us/j/69264190642

Opponent: Associate Professor Aron Szucs, ABB and University of Pecs, Hungary

The Doctoral thesis can be downloaded from: http://doi.org/10.63959/chalmers.dt/5788

Abstract:

This work evaluates representative automotive electric traction machines (e-machines) that do not rely on rare-earth elements (REEs) using finite element method (FEM) simulations and life cycle assessment (LCA) to compare their technical and environmental performance against PMSMs with REE-based magnets. The alternative machine types considered are the induction machine (IM), synchronous reluctance machine (SynRM), and electrically excited synchronous machine (EESM). Specifically, three IM configurations, two SynRM configurations, and two EESM configurations were analyzed, incorporating different combinations of conductor materials, aluminum (Al) and copper (Cu).

The analysis reveals that Cu-based configurations generally exhibit lower greenhouse gas (GHG) emissions due to superior efficiency and power density, while Al-based machines demonstrate reduced environmental impacts in categories such as toxicity and acidification. Notably, EESM and IM, both utilizing full copper conductors, emerge as promising alternatives to the Ref. PMSM in terms of global warming potential for high- or low-GHG electricity scenarios.

Beyond baseline comparisons, the study explores strategies for further GHG reduction, including the use of green virgin aluminum and improved material utilization during the punching process of electrical steel sheets, collectively referred to as “green manufacturing.” A sensitivity analysis on magnet production further suggests that, under favorable conditions, REE-free machines with Al conductors may achieve a lower carbon footprint than for the Ref. PMSM.

This work underscores the environmental trade-offs inherent in e-machine selection for EVs and highlights the critical importance of sustainable materials and manufacturing practices in future e-machine design, in addition to high efficiency and power density.