Rare Earth Free Motor Designs with MnBi

Need: Currently, electric motors used in electric vehicles currently rely on critical materials like neodymium and dysprosium. These materials are subject to wide price swings, and as demand increases for electric vehicles, availability and price may become prohibitive. Additionally, no domestic suppliers or manufacturers of these materials currently exist in north America, and 90% of supply is from China. Executive Order 13817, directs agencies, including DOE, to developing domestic alternative technologies and supply chains that do not rely on foreign sources or reduce demand of these critical materials. Approach: This Project will transition licensed DOE-developed MnBi permanent magnets to industry, and develop 80KW permanent motor alternating current (PMAC) motor designs meeting 2025 EETT roadmap goals for electric traction motors without the use of rare earth magnets. MnBi is unique in providing very high coercivities, similar to Rare earth (RE) magnets but using no critical materials.This project will validate motor designs, mature MnBi to Kg scale magnet production, and design advanced wide bang gap current control topographies can overcome the low temperature demagnetization concerns of MnBi. Phase I program Progress:Powdermet replicate AMES lab powder production and MnBi bulk magnet production using arc melting, milling, annealing, coating, and consolidation processes, and will continue to improve energy products through processing modification for the remainder of the STTR period. Bulk magnet coercivities above 9kOe were achieved to date. Powdermet scaled magnet production to larger batch sizes (250g) and magnet sizes (2”) using rapid consolidation of the MnBi with engineered interfaces using SPS and traditional warm pressing. Finite element analysis of PMAC motor designs incorporating advanced materials were carried out, comparing traditional NdFeB magnets and MnBi, and 80KW (130KW peak) motor designs, including efficiencies, thermal performance, and performance compared to RE reference designs. Nearly equivalent power densities could be achieved with reduced cooling requirements based on the high demagnetization resistance of MnBi at high temperatures. Phase II program: The phase II program will continue to develop scalable manufacturing processes for high energy MnBi at Kg scale, to produce magnets with >10MGOe at RT (goal of 12) of at least 100X15X10mm size for building a 10KW demonstration motor. Phase I motor designs will be fabricated at the 1-3KW (year 1), and 10KW sizes to verify performance and design, and an 80KW design will be generated for further demonstration. Additional motor topographies and advanced material insertions will be evaluated through trade studies to improve power density and cost. Current-controlled WBG controller topographies and programming will be developed to optimize motor performance. Commercial applications and benefits: Electric Vehicles are expected to reach 35% market share in the 2030’s, and will require lower cost and more efficient traction motors. MnBi can reduce or eliminate rare earth dependance in these motors, while reducing cost of magnets by 50% over ferrite and NdFeB materials. Greater use of electric vehicles reduces greenhouse gas, NOx, and particulate emissions, and reliance on fossil fuels.