Electromagnetic Modeling based Life Cycle Assessment of Rare-Earth-Free Propulsion Electric Machines for Vehicles
Doctoral thesis, 2025
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.
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.
Electric vehicle
Synchronous reluctance machine (SynRM)
Life cycle assessment (LCA)
rare-earth-element-free
Electric traction machine
Electrically excited synchronous machine (EESM)
Induction machine (IM)
EDIT room
Opponent: Associate Professor Aron Szucs, ABB, Helsinki + Associate Professor, University of Pecs, Hungary
Author
Meng-Ju Hsieh
Chalmers, Electrical Engineering, Electric Power Engineering
Meng-Ju Hsieh, Anders Nordelöf, Emma Grunditz, Torbjörn Thiringer, “Life cycle assessment of electric traction induction machines”. The International Journal of Life Cycle Assessment, 2025
Improved Parametric Representation of IM from FEM for More Accurate Torque Predictions: Simulations and Experimental Validations
IEEE Transactions on Industry Applications,;Vol. 60(2024)p. 6660-6671
Journal article
Maximum Torque Control Operating Points Estimation for Variable-Speed IM Applications by Parameter-Based Model
IECON Proceedings (Industrial Electronics Conference),;(2023)
Paper in proceeding
An Alternative to Determine IM Parameters Trends Affected by Magnetic Saturation Using Two-Stage Flux-Decay Test by FEM
2023 IEEE International Electric Machines and Drives Conference, IEMDC 2023,;(2023)
Paper in proceeding
Improved Parametric Representation of im from FEM for More Accurate Torque Predictions
2022 International Conference on Electrical Machines, ICEM 2022,;(2022)p. 599-605
Paper in proceeding
Research question: To what extent can electric machines without rare-earth elements compete with those that use them?
A promising solution to reduce greenhouse gas emissions is to increase the use of electric cars. However, most traction electric machines in electric cars today rely on permanent magnets made with rare-earth elements, such as neodymium and dysprosium. These materials make electric machines compact and efficient, but they raise concerns about the supply chain and cost risk. Additionally, mining and processing rare-earth elements can lead to negative environmental impacts, such as toxic pollution, which poses risks to drinking water.
To address these issues, electric machine designs that avoid the use of rare-earth materials are gaining increasing attention. While these alternatives avoid rare-earth elements, they often come with trade-offs like lower efficiency and power density compared to today’s state-of-the-art.
This research aims to answer the research question. By combining engineering simulations with life cycle assessments, this work helps identify sustainable solutions for the next generation of electric machines for electric cars.
A promising solution to reduce greenhouse gas emissions is to increase the use of electric cars. However, most traction electric machines in electric cars today rely on permanent magnets made with rare-earth elements, such as neodymium and dysprosium. These materials make electric machines compact and efficient, but they raise concerns about the supply chain and cost risk. Additionally, mining and processing rare-earth elements can lead to negative environmental impacts, such as toxic pollution, which poses risks to drinking water.
To address these issues, electric machine designs that avoid the use of rare-earth materials are gaining increasing attention. While these alternatives avoid rare-earth elements, they often come with trade-offs like lower efficiency and power density compared to today’s state-of-the-art.
This research aims to answer the research question. By combining engineering simulations with life cycle assessments, this work helps identify sustainable solutions for the next generation of electric machines for electric cars.
E-machine design for enhanced recyclability and minimized environmental impact
Swedish Energy Agency, 2020-09-01 -- 2025-09-30.
Volvo Cars, 2020-09-01 -- 2025-09-30.
Subject Categories (SSIF 2025)
Other Environmental Engineering
Vehicle and Aerospace Engineering
Power Systems and Components
Areas of Advance
Transport
DOI
10.63959/chalmers.dt/5788
ISBN
978-91-8103-331-1
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5788
Publisher
Chalmers
EDIT room
Opponent: Associate Professor Aron Szucs, ABB, Helsinki + Associate Professor, University of Pecs, Hungary