Comparative Thermal Analysis of Slotless and Slotted Permanent Magnet Synchronous Motor

Abstract The paper presents an extended comparative thermal analysis of slotless and slotted permanent magnet synchronous motors (PMSMs). To position the investigated motor topologies within modern drive system development, a brief classification-based background on slotless motors is included. Analytical lumped-parameter thermal models are derived to describe copper loss generation, temperature-dependent resistance, volumetric heat source implementation, and stator-to-ambient heat transfer. Three-dimensional thermal simulations performed in Autodesk Fusion are used to compare temperature fields and thermal gradients for both motor constructions under identical operating conditions. The results show that slotless PMSMs reach lower peak winding temperatures and exhibit a more uniform temperature distribution, primarily due to the absence of stator teeth and reduced internal thermal resistance. These findings support the application of slotless PMSMs in high-efficiency and high-reliability drive systems.