Purpose

Geopolitical challenges, coupled with the expected surge in demand for electric vehicles (EVs), may create uncertainties in the supply of rare-earth elements (REEs) used in permanent magnet synchronous machines (PMSMs), the predominant type of electric traction machine (e-machine) in EVs. This life cycle assessment (LCA) study benchmarks an REE-free alternative machine type, induction machine (IM), against a classic PMSM with REE magnets for EV application.

Materials and methods

Three IM variants are evaluated: one with copper (Cu) stator windings and Cu rotor bars, one with Cu stator windings and aluminum (Al) rotor bars, and one with Al stator windings and Al rotor bars. Beyond a baseline setup, the study also explores strategies to reduce GHGs, including using green virgin Al and enhancing the material utilization rate during the punching process for electrical steel sheets, referred to as a “green manufacturing” route. Furthermore, a sensitivity analysis of GHGs on magnet production is also conducted.

Results and discussion

The results show that the PMSM causes the least greenhouse gas (GHG) emissions due to its higher power density and efficiency. In contrast, the IMs with Al conductors exhibit lower environmental impacts in the categories of toxicity and acidification compared to those with (more) copper. The sensitivity analysis shows that IMs have the potential to display lower carbon footprints than PMSMs under favorable conditions. The research highlights the environmental trade-offs in e-machine design for EVs.

Conclusions

The study underscores the need for a sustainable perspective on e-machine materials and manufacturing processes. It demonstrates that REE-free IMs, particularly when paired with green manufacturing strategies, can be competitive alternatives to PMSMs in terms of environmental performance, depending on design and production choices.