Electromagnetic analytical model for axial-flux permanent-magnet machines with a double-sided rotor and an ironless stator

Purpose This paper aims to present a three-dimensional (3D) analytical model for axial-flux permanent-magnet machines with a double rotor and an ironless distributed-winding stator, incorporating magnetic edge effects to improve the accuracy of the analytical predictions. Design/methodology/approach The electromagnetic analytical model is developed by solving Maxwell’s equations in 3D Cartesian coordinates, adopting a linearization assumption at the mean radius. The solution is obtained using the subdomain method, with a vector potential formulation applied in the coil region and a scalar potential formulation in the air and magnet regions. The magnetic fields produced by the permanent magnets and the stator currents are then used to derive analytical expressions for the electromotive force (EMF), electromagnetic torque and the self- and mutual inductances. The analytical results are validated against those obtained from 3D finite element simulations. Findings The analytical results demonstrate high accuracy and confirm that the proposed model effectively accounts for magnetic edge effects without the use of correction factors while offering a substantial reduction in computational time. Practical implications The proposed analytical model offers a significant reduction in computation time compared to finite element simulations, providing an efficient and accurate tool for the design and optimization of axial-flux permanent-magnet machines. Its low computational cost and direct dependence on the geometrical and electrical parameters make it particularly well-suited for multi-objective design optimization and multi-variable parametric sweeps aimed at improving overall machine performance, which would be computationally prohibitive with full 3D finite element method simulations. Originality/value A new 3D analytical model has been developed to accurately analyze axial-flux permanent-magnet machines featuring a double rotor and an ironless distributed-winding stator. The developed model accounts for 3D magnetic edge effects without the need for correction factors and provides analytical expressions for the EMF, electromagnetic torque and both self- and mutual inductances.