Sinusoidal Shaped Surface Permanent Magnet Motor Using Cold Spray Additive Manufacturing

Abstract

With the global trend towards electrification of transport, the interest in various configurations of electric motors is growing. Several applications require low torque pulsations as it can lead to mechanical vibrations and acoustic noise. Optimization of the shape of the rotor permanent magnet (PM) has been the most effective technique for reducing torque pulsations. Unfortunately, the low versatility of the motor magnet fabrication technologies limits the development of new motor geometries. Cold spray additive manufacturing is used for shaping PMs for the direct fabrication of electric motor parts without the need for additional assembly steps. This fabrication technique allows an increase in the design flexibility of electrical machine geometries targeting improved performance. This paper presents rotor PM shaping design for radial flux inner rotor surface permanent magnet synchronous machines (SPMSM). PMs being shaped according to a sinusoid along the axial direction while the thickness of the magnet is kept uniform along the radial direction. The performance of the machine with sinusoidal shaped rotor PM (Model-B) is compared against a conventional rectangular shaped rotor PM (Model-A) design. The effect of sinusoidal shaped rotor PM shape on flux linkage, load torque, cogging torque and back EMF is analyzed and simulated using the 3-D finite-element method for both models. Also, the magnetization current magnitude required to completely magnetize the rotor PM fabricated using cold spray additive manufacturing is calculated.