Analysis and Realization of Disk-type Magnetically Levitated Motors

• Main Authors: Shu-Yuan Fan, 范淑媛
• Other Authors: Yaow-Ming Chen
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/94521001775158480865

博士 === 國立中正大學 === 電機工程所 === 96 === The objective of this dissertation is to analyze and realize two disk-type magnetically levitated motors (MLMs), one is the tetragonal-section MLM (TMLM) and the other is the pentagonal-section MLM (PMLM). The main difference between the TMLM and the PMLM is the shape of the iron blocks on the top of the two side teeth of each laminated thin steel core, for the TMLM is with tetragonal-section and for the PMLM is with pentagonal-section. The proposed MLMs provide rotary motion and offer numerous advantages. First, it can accomplish levitation force and propulsion force by using only a single power source. Sec-ondly, with a circular structure, it can provide unlimited traveling distance avoiding end effect for analyzing general characteristics associated to MLMs. Third, stabilization is improved by taking additional mechanical design consideration without using another set of electromagnet and complicated control. Based on the TMLM, analytical equations for magnetic flux density, induced current density on the secondary, and thrust and levitation force have been derived to help the pre-liminary selection of mechanic dimensions and to predicate the performance of the proposed MLMs. Then, computer simulations of flux plots, flux density distributions, thrust, and levita-tion force have been conducted to demonstrate the characteristics of the proposed MLMs. Same trend has been found between the analytical equations and the computer simulation re-sults. In this dissertation, the stabilization of the TMLM is further improved by replacing the iron blocks with tetragonal-section on the top of the two side teeth of each laminated thin steel core with the ones with pentagonal-section for shortening the air gap of the magnetic circuit. Mechanical structure analysis and experimental measurements are carried out to show the achievement of the faster rotational speed, smaller variation, higher efficiency and better con-trollability with this mechanical structure modification. In order to convince the feasibility of the proposed MLM, experimental measurements used to characterize the PMLM have been performed. These measurements include the rota-tional speed tests under different weights of load, rotational directions, and voltage to fre-quency ratios; the torque tests under different rotational speeds for different voltage to fre-quency ratios; as well as the levitation height tests under different input currents and opera-tional frequencies. The on-field experimental results have been reported to characterize the PMLM and to highlight the feasibility of constructing an MLM based on the linear induction motor (LIM) mechanical structure with transverse flux. The experimental results show that the electrical characteristics of the PMLM almost agree with its theoretical results which can be further used in developing control-strategies.