Bearingless segment motor with Halbach magnet

Abstract

Today magnetically levitated rotors are mainly used in applications where wearless operation and high life cycle are of importance (e.g. in the pharmaceutical, biomedical, chemical and semiconductor industry). The bearingless slice motor features a very compact design because three degrees of freedom (one translational and two rotatory) are passively stabilized by reluctance forces. Therefore, only two translational degrees of freedom remain to be actively controlled. This paper introduces a new bearingless segment motor (a subtype of the bearingless slice motor) featuring a Halbach magnet ring mounted on the rotor. Thus, no back iron is needed on the rotor and therefore the overall weight of the permanent magnet excited disc-shaped rotor is reduced to a minimum.The bearing forces which can be created by one optimized stator segment are calculated analytically. These results allow conclusions for the total force locus. A prototype is built and measurements verify the results of the analytic considerations.

Multi-Structural Optimization of Bearingless Permanent Magnet Slice Motor Based on Virtual Prototype in Ansoft Maxwell

“…To solve the multi-input and multi-output optimization problem in (12), a is utilized to simultaneously determine k α , k z , P Fe , P Cu , k, and T. According to the dimensionless multi-structural optimization function constructed, the fitness is calculated out using a GA based in MATLAB 9.0. Since the initial population selection of the GA is random, to ensure the reliability of the optimization results, 180 sets of experimental data are analyzed using the statistical method for each condition.…”

“…With the increasing demands for canned pumps and chambers in the semiconductor manufacturing industry, bearingless slice motors with wide air gaps were proposed in [10,11]. To achieve a compact and lightweight design, symmetric sets of Halbach magnet arrays are often used in BPMSM structural designs [12,13]. Considering feasibility and efficiency, optimization relying on the performance measurements of laboratory prototypes always focuses on qualitative analyses.…”

Design variants of the bearingless segment motor

“…No rotor back iron is needed in this case. A first prototype motor with 20 rotor poles was built and put into operation [11]. This motor has a similar operational characteristic as the first prototype with surface mounted permanent magnets.…”