3D Analytical Computation of the Torque in Axial Flux Permanent Magnets Couplings Based on Charges Model and Images Method

This paper presents a simple and accurate 3D analytical expressions to compute the force and torque of an axial flux magnetic couplings (AFMC) based on the equivalent magnetic charges and the images method. The proposed model is formulated and solved in a 3D Cartesian coordinate system by considering the assumption of linearization around the mean radius. Firstly, the magnetic flux density due to the cubic permanent magnets (PM), of one side of the magnetic coupling, is computed in 3D considering the magnetic end effects where the iron yokes influence is considered thanks to the images method. Secondly, the force and the torque among the magnets located in the opposite sides are obtained using the analogy between the electrostatic and magnetostatic forces. The derived analytical expressions depend directly on the geometrical and physical parameters of the AFMC. The analytical results are compared to those obtained with finite element simulation and experimental measurements.