Study on EV Traction Motors for Life Cycle Assessment Considering Changes in Winding Material and Magnet Configuration

Reducing the life-cycle CO2 emissions of electric vehicle (EV) traction motors requires a comprehensive evaluation of material selection, magnet configuration, and structural design. In this study, six motors—including a benchmark NdFeB-based PMSM—are designed under unified constraints of identical outer diameter, ampere-turns, and target torque (163 Nm), enabling a fair comparison of environmental performance. Electromagnetic field simulations are conducted to optimize each design, and life-cycle CO2 emissions are quantified using emission factors from IEEJ-IAS and standard material databases. The results show that manufacturing-stage emissions vary significantly depending on magnet and winding materials: the benchmark PMSM exhibits the highest manufacturing CO2 (42.1 kg-CO2), while the rare-earth-free PMaSyn.RM achieves the lowest value (28.4 kg-CO2). In contrast, use-stage emissions over 150,000 km are dominated by motor efficiency, ranging from 1820 kg-CO2 (PMSM-Cu) to 2030 kg-CO2 (Al-wound PMSM). Consequently, the total life-cycle CO2 spans from 1848 kg-CO2 (PMaSyn.RM) to 2072 kg-CO2 (Al-wound PMSM), indicating that rare-earth-free motors minimize manufacturing impact, whereas high-efficiency PMSMs reduce use-stage emissions. Furthermore, the study evaluates the practical feasibility of aluminum windings and rare-earth-free designs, identifying structural requirements such as dual-rotor configurations for aluminum conductors and flux-barrier optimization for ferrite-based motors. These findings provide quantitative insights into the trade-offs between material sustainability and operational efficiency, offering guidance for future EV motor development toward carbon neutrality.