Comparative Analysis of Axial Flux and Radial Flux Motors for UAV Propulsion: Design and Suitability Assessment 2024-26-0467

In the architecture of an Unmanned Aerial Vehicle (UAV), a crucial component responsible for the propulsion system is the electric motor. Over the years, different types of electric motors, including Brushless Direct Current (BLDC), have supported the UAV’s propulsion system in diverse configurations. However, in the context of flux flow, the Radial Flux Permanent Magnet Motor (RFPMM) has been given more priority than the Axial Flux Permanent Magnet Motor (AFPMM) due to its sustainability in design and construction. Nevertheless, the AFPMM boasts higher speed, power density, lower weight, and greater efficiency than the RFPMM, because of its shorter flux path and the absence of end-turn winding. Therefore, this paper focuses on conducting a suitability analysis of an AFPMM as a shaft-connected propeller-mounted motor, with the intention of replacing the RFPMM in UAV applications. The design of the AFPMM, incorporating topologies featuring a one-rotor, one-stator configuration, is considered. In this research, the physical dimensions of an AFPMM required to meet performance parameters are derived using systematic analytical equations. Furthermore, the design is executed using a multi-physics simulation tool to analyse the electromagnetic behaviour of the model. To validate the designed model and compare its characteristics, a prototype of BLDC RFPMM with similar output performance parameters is selected. The operating parameters are tested for compliance with the recommended output characteristics of the Original Equipment Manufacturer (OEM). Through reverse engineering, the design dimensions are obtained, and the electromagnetic behaviour is analysed using a multi-physics simulation tool. Moreover, based on the performance characteristics of the RFPMM, the design dimensions of the AFPMM are determined using sizing equations and assumed design variables. The suitability analysis, focusing on UAV behaviour is scrutinized to identify the most appropriate electric motor for ensuring sustainable and efficient operations.