Core/Shell Composite Soft Magnetic Material for Advanced Motors (REVISED)

For hybrid electric vehicle (HEV) applications, the Department of Energy (DOE) is directing an aggressive program to achieve rapid progress in permanent magnet (PM) machine development. To achieve DOE goals, PM motors must operate at twice the frequency of current electric motors used in hybrid-electric vehicles. Achieving these goals will require rotor and stator core materials with high electrical resistivity to reduce eddy currents and decrease total core losses during high frequency operation. This project will reduce core losses by using a powder metallurgy approach to create soft magnetic, high-resistivity, rotor and stator core materials. In particular, soft magnetic alloy powders will be coated with a nanolayer of a high resistivity, ferrimagnetic ferrite. The powders will be used to create dense composite parts with low porosity. This approach will isolate the electrically-conductive ferromagnetic regions with a shell of high resistivity ferrimagnetic material, thereby reducing eddy current losses while maintaining magnetic exchange coupling between metallic ferromagnetic regions. This exchange coupling is necessary to achieve high permeability materials with low hysteretic losses. Commercial Applications and other Benefits as described by the awardee: In addition to vehicle applications, improved permanent magnets should have application to distribution and power transformers, high reactance cores, communications equipment, high-efficiency fractional horsepower motors, large generators, pole pieces, and relays.