| Summary: | 碩士 === 國立中正大學 === 物理學系 === 85 === Both efficiency and cogging torque in a spindle motor has been
studied by varying the magnetization profiles of the rotor and
the geometry shape of the teeth of the stator. The torque
between the rotor and stator of a spindle motor is sensitive to
the number of magnetic poles, the magnetization profiles, the
magnetic field strength of magnets, and the geometry shape of
the teeth etc.. The cogging torque is a fundamental
phenomenon occurred between the stator and the magnetic rotor of
a spindle motor and is an obstruction in realizing constant
speed control or high accuracy of position control. In this
study, we reported the results of both experimental and
theoretical calculation about the optimal design of reducting
the cogging torque, but, still keeping almost the same torque
constant. The magnetization profiles can affect the torque of
magnetic coupling markedly. According to our MagNet52 finite
element analysis, radial magnetization profile offers a much
better torque constant. After smoothing the edge of the teeth
of the stator, we can reduce the cogging torque tremendously.
The mechanism of this reduction was explained by minimum net
integral of the product of normal and tangential magnetic flux
density with respect to the mechanical angle between the
stator and magnetic rotor of a spindle motor. Finally, our
experimental data are in good consistent with the theoretical
calculation.Details will be discussed.
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