ANALYSING, DESIGN, AND PROTOTYPING OF A HYSTERESIS MOTOR WITH NOVEL AND OPTIMUM STRUCTURE

This thesis introduces the design and analysis of a new hybrid hysteresis motor with combined axial and radial flux rotors aiming to improve the poor performance characteristics of the conventional hysteresis motors such as the output torque and efficiency. The proposed hybrid design incorporates the advantageous features of both the conventional axial and radial flux hysteresis motors in a unique structure. The design aspects and constraints of the proposed machine are based on a sample single-sided axial flux hysteresis motor. In order to analyze the electromagnetic performance of the proposed structure and investigate the geometry specifications of the designed machine, a 3-D Finite Element Analysis (FEA) is conducted. The hysteresis loop modeling is done based on the elliptical approximation of the hysteresis loop by considering the saturation during the FEA with an iterative method. Also, two analytical models are proposed to analyze the performance of the new hybrid hysteresis motor. At the first method, in order to analyze the electromagnetic performance of the proposed machine and investigate the geometry specifications of the designed machine, the structure is divided into two axial and radial planes and the Laplace's equation are solved in 2-D Cartesian and cylindrical coordinates for the field in the air-gap, the stator and the rotor disc subject to appropriate boundary conditions. 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 Magneto Motive Force (MMF) harmonics on the machine performance is estimated by an iterative approach. Afterward, the closed-form expressions for the developed torque are obtained in both planes and the results are stacked-up linearly by considering the basic of the superposition theorem. At the second method, the analysis of an axial flux hysteresis motor is investigated based on the parallelogram approximation of the hysteresis loop. This model is widely used in the analysis of the conventional hysteresis motor when the magnetic equivalent circuit method is employed. Because of the lack of analysis for the slotted stator, the magnetic analysis of a sample single-sided type is presented and the results of the analysis are extended to the hybrid structure. Then the yielded results are compared with the tests on a prototype. In this study, the effect of stator slotting, slot opening, and parasitic loss on the machine performance are investigated. Also, the sensitivity analysis of the magnetic and geometric parameters of the machine is evaluated. Finally, in order to investigate the electromagnetic performance of the proposed device and the accuracy of the design and analysis approach, a prototype is built. The test results validate the good performance of the proposed machine.