| Summary: | 博士 === 國立成功大學 === 機械工程學系碩博士班 === 98 === Creating a comfortable environment has become a sought-after goal for both home appliances and motor manufacturers due to the increasing consumer demand for an improved quality of life in recent years. Thus, the issues on how to minimize the vibration and noise of motors have gradually received substantial attention. This dissertation explores the effects of electromagnetic forces on the vibration found in permanent magnet brushless motors. Four research topics are investigated in this dissertation and they are: 1. Tangential force: the fluctuation of tangential force causes unstable output torque, and thus torque ripple and motor vibration are created. This study analyzes the main factor that results in torque ripple of permanent magnet brushless motors, i.e., back-EMF waveforms, and proposes a two-segment rotor structure to reduce cogging torque, higher-order harmonics, and torque ripple. 2. Radial force: this electromagnetic force acts on the stator and rotor in the radial direction and causes motor vibration as the rotor rotates. In this study, the effect of motor structure on the fluctuation of radial force is obtained by recording force loci figures. Moreover, the structure parameters which can reduce the radial force with the same output torque are examined. 3. Rotor eccentricity: rotor eccentricity is a common problem which induces motor vibration and noise. This dissertation presents the variation of torque ripple and radial force with various levels of rotor eccentricity. Furthermore, the electrical parameters are also analyzed to show the influence of rotor eccentricity. 4. Symmetric and asymmetric motor structures: in this study, the examination of torque ripple and radial force are presented with the symmetric and asymmetric motors. In order to recognize the main factor which seriously causes the motor vibration, the simulation and measurement of motor vibration are reported. Overall, this dissertation provides a good reference for motor designers to reduce motor vibration in the design procedures.
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