Abstract
Background: Analytical modeling of circumferential-flux disk-type hysteresis motors by using contemporary methods do not lead to accurate results, unlike other types of hysteresis motors. This is due to the considerable radial variation of magnetic field distribution inside these motors.
Methods: This paper proposes a novel approach to overcome aforementioned problem. Based on this approach, the motor is considered as the series connection of several imaginary thin motors, by radially dividing it into a finite number of narrow sections. Governing equations of each section are derived by using Ampere's Circuital Law, Magnetic Flux Continuity Law, and Faraday's Law of Induction. This procedure includes a new technique for considering the effect of air-gap leakage on exciting current of motor. Obtained equations have led to a new equivalent electric circuit for motor. To implement the proposed approach, a new iterative modeling algorithm with multiple nested iteration loops has also been introduced. This algorithm finds the working hysteresis loop of each section and the exciting current of motor, for any value of terminal voltage.
Results: Due to the generality of the proposed method, it has been successfully employed for modeling a multi-stack slotless motor. Some of the required parameters for modeling of this motor have been calculated by finite element analysis. Different performance characteristics of this motor, including input current, power factor, input power, core and copper losses, developed torque, and efficiency have been obtained over a wide range of terminal voltage.
Conclusion: Proposed method could properly predict the radial variations of magnetic field distribution.
Keywords: Analytical modeling, circumferential-flux motors, disk-type hysteresis motors, finite element analysis, multi-stack slotless motors, performance evaluation.
Graphical Abstract
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