Analysis of an E-Core Interior Permanent Magnet Linear Oscillating Actuator

This paper presents the design, analysis and experimental validation of a single-phase tubular E-core interior permanent magnet (IPM) linear oscillating actuator (LOA). Firstly, the topology is described and its electromagnetic performance, in terms of the air-gap flux density, flux-linkage, back-emf coefficient and thrust force-displacement characteristic, is analyzed by finite element analyses. It shows that it is simple to manufacture compared to E-core SPM actuators and solves the problem of significant leakage flux in C-core actuators. In addition, the E-core IPM actuator is capable of producing reluctance force due to the salient mover structure, which enhances the spring stiffness and is conducive to the oscillation, although has no contribution to the output power. The influence of the magnet pole ratio and split ratio on the performance of the IPM LOA is investigated, and the optimal parameters have been identified with reference to the peak value and flatness of the excitation force-displacement characteristic. Finally, the predicted thrust force characteristics are validated by measurements on a prototype actuator.

I. Introduction

Recently, single-phase permanent magnet (PM) linear oscillating actuators (LOAs) become increasingly popular in many industrial applications, such as compressors, pumps, vibrators, etc. [1]–[6], mainly because of their inherent high power density and high efficiency. In [6] a planar flux concentration type IPM LOA was proposed, and its performance further was further analyzed in [7]. While due to the advance of soft magnetic composite material [8] proposed a tubular quasi-Halbach magnetized PM LOA, the performance of machines equipped with non-magnetic and ferromagnetic mover back-iron was compared, the efficiency of >93% being recorded for both cases. In [9] alternative actuator topologies were described, and their finite element (FE) predicted electromagnetic performance was compared. Consequently, a 3-pole interior PM (IPM) topology was identified and further analyzed in [10]. However, the investigation in [8]–[10] only focused on the C-core PM actuators.