Amorphous and Nanocomposite Magnets for High Efficiency, High Speed Motor Designs
Subhashish Bhattacharya
Project runs from 03/01/2017 to 09/30/2020
$200,000
Amorphous and Nanocomposite Magnets for High Efficiency, High Speed Motor Designs
Electric motors use soft and/or hard ferromagnets to produce or direct spatiotemporally varying magnetic flux. World Bank reports [1] the US consumed ~4 trillion kW-h of electricity in 2009 with ~30% consumed by motors. New materials can reduce losses (~58%) between the rotor and stator with a 1% improved motor efficiency results in saving ~12 billion kW-h. Rare earth (RE) permanent magnet (PM) motors are popular but soft magnetic materials (SMMs) provide the greatest potential for energy savings [2-4]. Supply constraints on RE elements (China controls ~ 80%), cause concerns which led NATO to classify them as critical elements [5-6]. We will demonstrate RE-free 5 kW motors with 4% increased efficiency using metal amorphous nanocomposite (MANC) SMMs. A 200 W power loss, portioned equally, will need power reductions of: a) controller: 50 W; (b) copper loss: 50 W; (c) iron loss: 50 W; (d) windage, 50 W.
MANCs are a transformational technology to increase efficiency and limit RE use in high speed electric motors (HSEMs). Hybrid motors employ a REPM rotor and high induction SMM stator. New SMMs replacing laminated FeSi in stators can reduce motor size [3-4]. CMU MANC SMMs [7] have inductions comparable to Si-steels and resistivities [8] to enable high switching f’s necessary for high torques to allow motor size and weight reduction. We will investigate MANC motors targeting 1-10 kHz frequencies in stator geometries for HSEMs. Materials development builds on Fe-Co [9], Co-rich [10] and Ni-rich [11] MANCs with high inductions, low losses, strain induced anisotropy and excellent mechanical and high-T magnetic properties. MANC SMMs investigated in high-f ARPA-E power transformation applications resulted in a T2M plan to penetrate motor markets. MANCs have (1) low direct-current (dc) hysteresis losses; (2) thinner laminations offering lower ac eddy-current losses. Lower iron losses than Si steel sheets, allow MANC motors to operate at higher rotational speeds. PPMT (Parallel Path Magnetic Technology) topology motors with Co-base MANCs, as compared to Si steel, allowed a high-speed design reducing machine size (~70 %), and RE hard magnet volume (~83 %).