This Small Business Innovation Research (SBIR) Phase I project aims to develop a novel soft magnetic material for electric motor cores, a fabrication process to make components from the material, and an electric motor configuration leveraging the benefits of the material and fabrication process. The approach is to utilize a new single-step net-shape fabrication technique based on uniform-droplet spray deposition in a reactive atmosphere to produce an isotropic metal microstructure characterized by small domains of high permeability and low coercivity with a controlled formation of insulation boundaries that limit electrical conductivity between neighboring domains. This design is expected to provide a superior magnetic path while minimizing losses due to eddy currents, and eliminating design constraints associated with anisotropic laminated cores of conventional motors.
The broader/commercial impact of this project will be the potential to provide spray-formed winding cores for hybrid-field motors to increase output, improve efficiency and reduce material scrap during fabrication, thus lowering the cost of electric motors. Considering the extensive use of electric motors in numerous applications, including industrial machinery and automation, robotics, heating, ventilation and air conditioning systems, appliances, power tools, medical devices, automotive applications, electric vehicles, military equipment etc., there is an increasing need for electric motors with improved performance, higher efficiency, and lower cost. This project is expected to have a significant commercial and environmental impact by providing low-cost and high-efficiency electric motor cores.
The present NSF SBIR project focuses on the development of a novel soft magnetic material for electric motor winding cores, a fabrication process to produce components from the soft magnetic material, and an electric motor topology leveraging the benefits of the new material and fabrication process. In particular, a unique single-step near net-shape fabrication process based on metal spray deposition in a reactive atmosphere is utilized to produce an isotropic metal microstructure characterized by small domains of high permeability and low coercivity with a controlled formation of insulation boundaries that limit electrical conductivity between neighboring domains. The resulting material for motor winding cores provides an excellent magnetic path while minimizing energy losses associated with eddy currents, and eliminates design constraints associated with anisotropic laminated cores of conventional motors, thus allowing for an innovative hybrid-field motor topology with improved performance and efficiency. In Phase I, feasibility of the proposed approach was investigated via modeling of the material to study the effects of key parameters of the microstructure on the electromagnetic properties of the material, fabrication of samples of the material and characterization of their physical properties, and modeling of the performance, efficiency, material scrap and cost for a hybrid-field brushless direct-current motor. The outcomes of each of the above research tasks can be outlined as follows. (a) The results of modeling of the material suggest that it is feasible to achieve the target electromagnetic properties. The desired domain size and insulation thickness as well as the maximum tolerable level of defects in the insulation boundaries were identified as part of the modeling exercise. (b) The use of metal spray deposition techniques for near net-shape deposition of specimens of simple geometries with an ordered microstructure was successfully demonstrated. Two metal spray deposition methods were evaluated, namely uniform droplet spray deposition and thermal spraying. The spray deposited material was shown to significantly lower eddy current losses compared to pure iron feedstock. (c) Electromagnetic simulations of a hybrid-field motor confirmed the initial hypothesis that higher power output can be produced compared to a similarly sized conventional motor in access of the initially targeted level. Similarly, material waste and cost analyses predicted reductions in line or beyond the initial estimates. In summary, the Phase I research outcomes successfully demonstrated feasibility of producing a soft magnetic material with the desired ordered microstructure via metal spray deposition in a reactive atmosphere, and validated the expected benefits of the proposed hybrid-field motor technology with stator cores utilizing the new soft magnetic material. Considering the extensive and increasing use of electric motors on a global scale, the disruptive change resulting from the proposed hybrid-field motor technology with spray-formed stator cores is expected to provide significant commercial, societal and environmental benefits, including improved manufacturing efficiency, waste reduction and energy conservation. It has a potential to take away the advantage of low-cost manufacturing regions outside the U.S., which are favored in today’s global economy, and advance the competitive nature and state of the art in a number of U.S. industries, including robotics, semiconductor and LED process equipment, industrial automation, electric vehicles, HVAC systems, appliances, power tools, medical devices, military and space exploration applications.
