Analysis and Torque Calculation of an Axial Flux Hysteresis Motor Based on Hyperbolic Model of Hysteresis Loop in Cartesian Coordinates

Like the other types, an axial flux hysteresis motor (AFHM) is a self-starting synchronous motor with outstanding characteristics, such as high constant starting torque and low starting current. In this paper, an AFHM is analyzed by linearly expanding the structure and solving Laplace's equation in a 2-D Cartesian coordinates for the field in the air gap, and the stator and the rotor disc subject to appropriate boundary conditions. At the first step, with respect to the elliptical approximation and considering the complex permeability concept in the Cartesian coordinates, the hysteresis loop is modeled. Next, the field equation is modified by the hyperbolic approximation of the hysteresis loop to investigate the effects of the minor loops described by the harmonic components of the field, and then, the impact of the magnetomotive force harmonics on the machine performance is estimated by an iterative approach. Afterward, the closed-form expressions for the developed force and torque are obtained. Finally, the device is prototyped whose experimental results agree well with those extracted from the analytical model.