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Title: The design of hybrid stepping motors aided by three dimensional finite element analysis
Author: Jolliffe, Clifford Mark
ISNI:       0000 0001 3591 7538
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1999
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Though the hybrid stepping motor has a long and proven history, in terms of toughness, accuracy of position and the ability to operate in open loop, motor performance improvements can still be made in terms of the physical structure of the motor's components. It is impossible to build a complete solution of the hybrid stepping motor using simple analytical functions or equivalent circuit representations. This is due to the difficulties introduced by the motor's highly non-linear three dimensional magnetic structure, of which the doubly salient tooth structure, axial magnet, and back iron all complicate the situation. However, with the recent advances in three dimensional finite element software a comprehensive study of the motor has been achieved in this thesis. This has allowed improvements to simpler two dimensional based mathematical models, which allow faster computation of the motor's electromagnetic performance. To aid modelling, novel equations which accurately model today's high permeability steels have been developed. These are shown to be more accurate than the established Jiles-Atherton method. Inductance calculations of the steel's flux paths have been comprehensively improved by the use of elliptical functions. The thesis concludes with the design of two quite individual new machines. The first dramatically improves a motor's power output, smoothness, noise levels, and resonance by modifying the tooth structure. The second uses soft magnetic composite materials to provide an isotropic path for cross lamination flux which flows in a stator's back iron. Both new designs are shown to offer a significant improvements to the high speed torque capability of the hybrid stepping motor.
Supervisor: Not available Sponsor: Stebon Ltd. ; Great Britain. Dept. of Trade and Industry (DTI) ; Science and Engineering Research Council (Great Britain) (SERC) ; University of Warwick. Dept. of Engineering
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TK Electrical engineering. Electronics Nuclear engineering