| Summary: | 博士 === 國立成功大學 === 機械工程學系碩博士班 === 92 === With the rapid progress in computer technology, the need for mass data storage such as optical and magneto-optical devices has increased considerably over recent years. The disk drive for these devices requires high precision spindle motors for fast and accurate data access. This thesis presents a novel two-phase motor design for digital video disk（DVD）and compact disk （CD）spindle applications. The construction of this new DC brushless motor is basically of a sandwich type, which has the distinct advantage of low manufacturing costs due to its simple stator structure and windings. Also in contrast with existing single-phase spindle motors, the proposed two-phase configuration eliminates the dead starting point and significantly reduces torque ripple.
This sandwich type motor with axial-windings and the radial-air-gap has inherent 3D flux distribution, which requires considerable computational time for computer-aided design and analysis. This study proposes an analytical method based on an equivalent magnetic circuit, where the permeance distribution per salient pole is calculated using the boundary element method. This is particularly suitable for solving partial differential equations and since the basic voltage equation can be deduced, the detent torque can be calculated analytically using the energy method. The proposed approach is computationally efficient and suitable for the optimal design of motors with inherent 3D flux distribution.
A prototype of this new two-phase motor design is made for performance evaluation and a drive circuit is developed for testing both DVD and CD-ROM drives. Operational tests showed the optical disk drive satisfied performance requirements by successfully accessing audio and visual signals. Experimental results also indicated that commercially available three-phase motor drive ICs can be effectively adapted to work with the two-phase motor design, giving it some promising applications.
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