Abstract An advanced electric motor with hybrid-field topology has been developed for automotive traction applications. Departing from the conventional radial- and axial-field designs, the hybrid-field motor features three-dimensional magnetic flux paths, which are enabled by a novel isotropic soft magnetic material produced by a unique additive-manufacturing process based on spray forming. The motor is expected to offer an unprecedented combination of high power output, compact size, low weight and energy efficiency, achieving more than two times higher power density than state-of-the-art high-performance traction motors. 1. Introduction A majority of electric motors today utilize winding cores made of laminated silicon steel [ 1, 2], as illustrated in Figure 1. The laminated construction has been adopted as a means of controlling energy losses due to eddy currents. However, the laminations constrain motor designs to topologies with two-dimensional magnetic flux flow, such as radial- and, less commonly, axial-field arrangements, which limits the performance potential of conventional motors [ 3, 4]. The laminated construction also adds manufacturing complexity and cost – it takes at least nine steps to produce a conventional motor stator alone. In order to address the limitations of the conventional motor technology, an advanced soft magnetic composite has been Page 1 of 8 engineered by Persimmon Technologies Corporation to replace laminated winding cores by solid isotropic components that can channel magnetic flux in three dimensions while suppressing formation of eddy currents and, therefore, the energy losses associated with them. Unlike conventional soft magnetic composites [5, 6, 7], the components are produced by a unique additive- manufacturing process based on thermal metal deposition, referred to as spray forming, in a reactive atmosphere [ 8, 9]. Figure 1. Conventional permanent-magnet brushless motor with laminated winding core. The spray-formed soft magnetic composite enables a new class of advanced electric machines [ 10], referred to as hybrid-field motors, which feature three-dimensional magnetic flux flow, departing radically from the conventional radial- or axial-field topologies. The geometry of the hybrid-field motors is selected to maximize the available volume for the magnetic flux flow, therefore increasing power density, while reducing energy losses. In other words, the spray-formed soft magnetic material enables smaller, lighter motors with higher power output and better energy efficiency. This paper presents a conceptual design of a hybrid field traction motor, which targets applications in hybrid vehicles, small electric cars, electric cars with multiple motors and electric motorcycles. The stator of the motor features a spray-formed core with three- dimensional magnetic flux paths, high-density windings and direct liquid cooling. The rotor employs permanent magnets and iron teeth for added reluctance torque.Spray-Formed Hybrid-Field Traction Motor 2017-01-1225 Published 03/28/2017 Jayaraman Krishnasamy and Martin Hosek Persimmon Technologies Corporation CITATION: Krishnasamy, J. and Hosek, M., "Spray-Formed Hybrid-Field Traction Motor," SAE Technical Paper 2017-01-1225, 2017, doi:10.4271/2017-01-1225. Copyright © 2017 SAE InternationalDownloaded from SAE International by University of British Columbia, Sunday, July 29, 2018The benefits of the hybrid-field motor in traction applications include a more compact and/or lighter drivetrain, improved dynamics of hybrid and electric vehicles, and increased range for electric vehicles. In addition, the applications of the hybrid-field motor technology extend beyond the electric drivetrain, including electric supercharging and various drive-by-wire systems, such as steering and brakes. The text is structured as follows: a new hybrid-field motor topology is introduced in Section 2; the process of spray-forming a motor stator c