In this paper, an improved tubular Halbach surface-mounted permanent magnet (HSPM) linear oscillating actuators (LOAs) with end ferromagnetic pole pieces is proposed. Generally, the end magnet rings are exposed to air due to the inherent opening structure of LOA, resulting in a rather larger reluctance of end air gap and a lower air-gap flux density. Therefore, the analysis on the end air gap is of great significance for LOA performance. Considering this fact, the ferromagnetic pole pieces are added at both ends of the support tube of LOA, trying to direct the magnetic fields in desired paths and enhance the electromagnetic performance of LOA. Two HSPM LOAs with ferromagnetic and without ferromagnetic pole pieces are simulated, built and tested. The results show that the electromagnetic performance of the proposed design is superior to the original. Moreover, its cost and volume are approximately unchanged. The proposed design plays a significant role in enhancing LOA performance and efficiency.

A Halbach permanent magnet (PM) tubular linear voice coil motor (LVCM) with a semi‐closed structure is developed to enhance the thrust density in this study. Generally, the end of conventional LVCM is open and suffers from the considerable end reluctance. The usage of Halbach array in LVCM makes this problem more prominent although it improves the air‐gap flux density greatly. The flux at the end of LVCM can be guided to improve the air‐gap flux density. Therefore, this study aims to constrain and direct the magnetic field at the end of a Halbach PM LVCM by using a ferromagnetic auxiliary yoke to construct a semi‐closed structure. Magnetic equivalent circuit method is utilised to analyse the effect of the auxiliary yoke on air‐gap flux density. Besides, finite element analysis is used to analyse the magnetic circuit and design the parameters of LVCM. The semi‐closed tubular LVCM topology is manufactured and the effectiveness of this topology is validated by experimental measurements. Results show that the thrust density of LVCM is improved effectively by using an auxiliary yoke at the end.

Generally, for small‐ and medium‐sized tubular permanent‐magnet (PM) linear actuators, PM structures can be divided into two categories. One is interior PM (IPM) structure and the other is surface‐mounted PM (SPM), involving a compromise between flux per pole and magnet leakage flux. This study proposes a novel semi‐IPM (s‐IPM) structure for a tubular linear actuator having the advantages of high flux per pole of IPM and small magnet leakage flux of SPM. The air‐gap flux density and the average thrust are analysed and compared with IPM and SPM by the magnetic equivalent circuit and finite element analysis. Moreover, the s‐IPM structure is also compared with Halbach PM array in terms of the average thrust and the magnet utilisation. Four prototype actuators with different PM structures are built and tested. Both the theoretical and experimental results show that the magnet utilisation of the s‐IPM structure is the largest while its cost and volume are approximately unchanged. The proposed s‐IPM actuators are of great prominence in high‐magnet‐utilisation and low‐cost applications.

In the case of designing linear voice coil motors (LVCMs), the aluminium tube is usually used to support and fix the windings. Due to the high‐speed linear reciprocating motion, the eddy‐current damping force in aluminium tube has a large effect on the dynamic characteristic of LVCMs and weakens the resultant force. In this study, an LVCM with forward winding is studied. The cause of eddy current damping force in the original structure of the aluminium tube is analysed, and the corresponding mathematic model is established which is verified by finite element method. To restrain the damping effect, three restraining measurements have been discussed. Then a novel structure of aluminium tube with axial slits and ribbed stiffeners is proposed according to the simulation analysis. During the experimentation process, the mover resultant force is replaced with its acceleration. Results show that the mover acceleration of LVCM with stiffened aluminium tube is bigger than that of the initial one. Hence the resultant force of the proposed structure is improved effectively and the new structure has a good inhibition effect on eddy‐current damping effect.

The slotless tubular permanent magnet linear motor (STPMLM) offers obvious advantages when it is applied to the punching system, such as space saving and controllable impact strength. Herein, the mechanical and electromagnetic coupled differential equations were established to present a comprehensive analysis of the relationship between mover mass and motor performance in the punching system. The travel time of the punching movement was expressed analytically under the condition of the mover obtaining the same impact kinetic energy, and the relationship between the mover mass and the resistive energy consumption in one punching process was also deduced under the same condition. Then the analytical results were validated by a numerical model. The studies show that a lighter mover mass can contribute to less resistive energy consumption and faster dynamic response in the punching applications. Based on that, a STPMLM with special‐shaped yoke was designed for lighter mover mass. Moreover, prototype experiments including static thrust characteristic and dynamic performance were conducted. The experimental results proved that the proposed permanent magnet linear motor with special‐shaped yoke can improve the dynamic performance and reduce resistive energy consumption while ensuring that the electromagnetic performance is not affected .