Influence of segmentation of ring-shaped NdFeB magnets with parallel magnetization on cylindrical actuators.

Paulo Eckert,Evandro Goltz,Aly Filho

doi:10.3390/s140713070

Abstract

This work analyses the effects of segmentation followed by parallel magnetization of ring-shaped NdFeB permanent magnets used in slotless cylindrical linear actuators. The main purpose of the work is to evaluate the effects of that segmentation on the performance of the actuator and to present a general overview of the influence of parallel magnetization by varying the number of segments and comparing the results with ideal radially magnetized rings. The analysis is first performed by modelling mathematically the radial and circumferential components of magnetization for both radial and parallel magnetizations, followed by an analysis carried out by means of the 3D finite element method. Results obtained from the models are validated by measuring radial and tangential components of magnetic flux distribution in the air gap on a prototype which employs magnet rings with eight segments each with parallel magnetization. The axial force produced by the actuator was also measured and compared with the results obtained from numerical models. Although this analysis focused on a specific topology of cylindrical actuator, the observed effects on the topology could be extended to others in which surface-mounted permanent magnets are employed, including rotating electrical machines.

Highlights

Nowadays there is a growing concern about power efficiency and high force density actuators to produce linear movement, for example in industrial applications and active suspension [1,2]
In order to evaluate the effects of parallel magnetization on the prototype with eight segments, measurements of static axial force, normal component of magnetic flux density, and tangential component of magnetic flux density in the air gap at were carried out
The prototype with eight segments had its force reduced by 3.9% when compared with simulation results of another one with ideal radial magnetized permanent magnets

Summary

Introduction

Nowadays there is a growing concern about power efficiency and high force density actuators to produce linear movement, for example in industrial applications and active suspension [1,2]. The simple concept makes it easy to design these actuators with high power efficiency and with high force density [3]. They employ ring-shaped magnets, ring-shaped coils and ferromagnetic cores. For each different permanent magnet shape and size a specific magnetizing fixture must be employed. Ring segmentation and parallel magnetization, such as in the examples shown in Figure 1b,c, are often preferred since it reduces costs and results in an easy way of manufacturing the permanent magnets [4,5]

Objectives

Results

Conclusion