Double-layer composite Halbach array linear motor

The application of mechanical products in many situations involves linear motion. The cylinder head of an internal combustion engine (ICE), a mechanical product, contains intake and exhaust valves. These valves open or close using the linear motion converted by the camshafts rotated by the engine. A typical engine is operated with a single cam profile; depending on the engine rotation, there are areas where the cam profiles do not match, resulting in a poor engine performance. An intake and exhaust system with an actuator can solve this problem. In a previous study on this system, the geometry and processing during manufacturing were complex. Therefore, in response, a linear actuator operated by Lorentz force with a coil as the mover was designed in this study. Through an electromagnetic field analysis using the finite element method, a three-phase alternating current was applied to the coil, assuming that it would be used as a power source for a general inverter. Consequently, the thrust obtained in the valve-actuation direction was 56.7 N, indicating improved axial thrust over the conventional model.

This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator.

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Free-piston linear generator (FPLG) is regarded as a promising power generator system for hybrid electric vehicle. The core component of FPLG, linear motor, requires careful design to match the system performances. In this paper, for required performance, a novel double-sided flat permanent magnet linear motor with dual Halbach is proposed. This motor is composed of four modular unit stators on both sides of the mover. Fractional-slot (7-poles/6-slot) and concentrated windings are adopted to each unit for high power, low thrust ripple. The relationship between the linear motor performance and structure parameters is developed and applied to design the size of linear motor. To verify the design of this motor, the two-dimensional finite-element model is established. The feature of output power in motoring and generating model are analyzed. In addition, a prototype is developed and tested in an experimental platform, which consists of rotating electrical machine and crankshaft connecting rod system. In terms of system output power, the experimental data is in well agreement with the finite-element results.

In this paper, an electromagnetic analysis study of a double-sided linear permanent magnet (PM) motor topology is conducted both for conventional and Halbach array magnet assemblies. Halbach arrays can condense flux lines on the one side of magnet assembly and cancel them on the reverse side, so they enable light motor structures due to the lack of back iron material. By means of the analyses, the critical performance criteria of linear motor are investigated. The designs are verified experimentally. The induced voltages and force production of prototype motors are captured to validate the design study. The findings show that Halbach array magnet assembly type linear motor has superiority for force production and lightness of design.

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Permanent magnet (PM) actuators with linear, rotary and spiral motions have been applied to many fields of industrial and agricultural drives. In this paper, a novel double-stator linear-rotary PM actuator was presented for the integration of mechatronics. The novelty of proposed actuator is the asymmetric-pole outer stator with consequent-pole (CP) PMs and the special mover with Halbach-array PMs. By combining the independent magnetic circuits of two sets of windings with the magnetic isolation characteristics of the fault-tolerant tooth, the double-degrees-of-freedom motions and its decoupling control can be realized, which enhances fault tolerance. By adopting CP asymmetric-stator and Halbach-array structures, it is possible to enhance the inner air-gap effective flux density to improve thrust force, as well as to increase torque performance and PM utilization. Furthermore, the magnetic field coupling characteristic was analyzed. The associated electromagnetic performances were predicted by using the finite-element method.

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The ironless permanent magnet linear synchronous motor (IPMLSM) is widely used due to low thrust ripple and fast response. Its disadvantage is low thrust density. The novel double-layer winding IPMLSM (DW-IPMLSM) with quasi-Halbach magnets can improve the thrust density. However, it also makes the winding structure asymmetric. Based on finite element (FE) model, this paper investigates the influence of winding asymmetry on force performance. The results show that the influence of winding asymmetry on thrust ripple is great, while the normal force is slightly affected and it needs to be considered only in precise application. Moreover, compared with traditional single-layer IPMLSMs, the proposed DW-IPMLSM is proved to have higher thrust density and smaller thrust ripple.

This article proposes a practical design guide for a linear electromagnetic actuator based on the concept of magnetic screw transmission, in which manufacturing and assembly technologies are investigated. The surface-inserted design is first used to form a required helical-shape magnetic pole, which exhibits simple processing, high precision, and robust structure. Moreover, different topologies are developed using the 3-D finite-element analysis aided design, with the goal of optimizing thrust force. In addition, different number of permanent-magnet (PM) segments are first proposed to reduce the cogging effect. Afterward, the linear actuator integrates the rotary machine and the magnetic screw together to construct a compact design and decouples the magnetic circuits. The decoupling design focuses on the self-shielding effect of the Halbach PM array, and the special bearing supports are selected to avoid the eccentricity. Finally, a prototype is built using the developed techniques. Experiments are carried out on a linear test bench, verifying the theoretical analysis.

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This paper proposes the application of a specific topology of coreless linear tubular actuator for semiactive and active suspension systems. The actuator consists of two quasi-Halbach arrays of permanent magnets, inner and outer, and a moving-coil armature. Some of the advantages of this actuator for the proposed applications include low moving mass, low ripple of force, reduced magnetic losses, and high force density. The paper also introduces a new method for determining actuator requirements to operate with an active and/or semiactive suspension system and presents the application of the proposed approach to a harmonically base excited single degree-of-freedom suspension system. Additionally, the electromagnetic model for magnetic field distribution, open-circuit induced voltage, and axial force and force ripple was developed and validated by means of finite-element analysis and with experimental results obtained from a prototype.

This paper concerns the optimization of eight different quasi-Halbach magnet array structures that are used in a dual-layer moving-magnet planar motor. These magnet arrays vary in number of magnets per pole and contain both cuboidal and trapezoidal prism magnet shapes. The parameters of the magnet structures are optimized to maximize the acceleration of the planar motor. The resulting accelerations and force ripples of the planar motor are compared for the optimal magnet structures. The results show that the studied magnet arrays improve the acceleration of the planar motor compared to the benchmark magnet array with three cuboidal magnets per pole. A maximum increase in acceleration of 10.1 % is achieved, while the force ripple is reduced by 10.2 % in any direction of movement.

To reduce the permanent magnet (PM) usage and cost, the improved Halbach tubular permanent magnet linear synchronous motor (IH-TPMLSM), which has unequal thickness of the radial and axial magnetized PMs located in the mover, is developed in this paper. Taking the maximum average thrust as the optimization objective, the single-step optimization method based on sensitivity analysis is used to optimize motor under the same current density by finite element (FE) analysis. The influence of the pole-pitch τ on the detent force is analyzed. According to the comparison of optimized TPMLSMs, the results show that when pole-pitch τ = 30.5mm and the full-pitched winding disposition τs = 31.5mm, the detent force is reduced by 55.87%. Finally, the open-circuit back EMF, air gap flux density, the thrust of the IH-TPMLSM and the quasi Halbach TPMLSM (QH-TPMLSM) are compared. The quantity of PMs of the IH-TPMLSM is 15.27% lower and the average thrust is 4.01% higher than that of QH-TPMLSM. Meanwhile the thrust ripple is reduced by 36.12%.

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Permanent magnet linear motors (PMLM) have gained increased popularities in a wide range of applications. However, they generally suffer from considerably lower force densities. In this paper, a novel doubly yokeless PMLM equipped with quasi-Halbach trapezoidal-shape permanent magnets is presented to both increase the thrust force density and suppress the thrust ripple. Both the stator and the translator are yoke-free, and therefore, the increase of the installation space for the windings is conducive to enhancing the magneto-motive force and the thrust density of the motor. An analytical model is developed to predict the magnetic field distribution and electromagnetic performance of the doubly yokeless PMLM, and finite element computations are undertaken to validate the effectiveness and accuracy of the proposed model. The thrust performance is then optimized against magnet parameters under a specific set of volumetric constraints to the improve the thrust force quality. It is shown that the Halbach ratio and bottom angle of the trapezoidal magnets have significant impacts on the thrust force quality (in terms of both the average thrust and thrust ripple), and optimal values for the two parameters are obtained. The benefits of the doubly yokeless PMLM are highlighted by comparisons with a conventional PMLM with iron yokes.

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This study investigates the modeling and dynamic analysis of three coupled electromechanical systems, emphasizing interactions between a magnetic linear drive and frictional contact with flat springs. The experimental setup includes a table driven by a three-phase permanent magnet linear synchronous motor (PMLSM) using an LMCA4 inductor, LMCAS3 magnetic track, and Xenus XTL controller. Mechanical phenomena such as stick-slip friction and impulsive loads are observed, particularly due to the rapid buckling of flat springs. These springs transition between sliding friction and fixation, impacting the motor’s operation during reciprocating velocity trajectories and generating acoustic emissions. Numerical simulations using COMSOL Multiphysics evaluate the magnetic field and system geometry in two- and three-dimensional spaces. Key findings include mechanical stick-slip vibrations, numerical modeling of the linear drive, and comparative analysis of experimental and simulated inductor current variations. Additionally, energy loss mechanisms under irregular loading conditions are assessed. The results highlight the coupling between friction-induced current changes and magnetic field variations, elucidating their impact on motor efficiency, vibration propagation, and acoustic emissions. The study provides insights into optimizing the design and reliability of coreless linear motors for precision applications under discontinuous loading.

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Based on the prototype Halbach planar magnet array (HPMA), a honeycomb Halbach flexible permanent magnet array (HHFA) is proposed in this article. HHFA can effectively optimize the magnetic field distribution, increase the magnetic field strength, and reduce the magnetic field distortion. The magnetic flux density distribution for HHFA was obtained through a numerical analytical approach. The simulation and comparative analysis show that the intensity amplitude of the magnetic field generated by HHFA is 23% higher than that of HPMA, and the periodic distortion rate, amplitude fluctuation of the magnetic field, and harmonic distortion of HHFA are optimized compared with HPMA. The simulation results demonstrate that magnetically levitated planar motor (MLPM) employing HHFA exhibits superior electromagnetic thrust coefficient and electromagnetic force stability compared to MLPM utilizing HPMA.

To achieve high thrust density in electromagnetic launch systems, this study proposes a collaborative optimization method for the dimensional design of permanent magnet (PM) arrays. A moving-magnet planar motor topology is adopted, and a one-dimensional analytical magnetic field model is established for rapid computation. A two-stage particle swarm optimization (PSO) strategy is implemented to maximize the absolute average z-direction flux density under strict mass constraints. The optimized design achieves a width ratio $\alpha$ increased from 0.5 to 0.7 and a PM thickness expanded from 25 mm to 35 mm. COMSOL simulations verify a 17.2% improvement in the absolute average z-direction flux density, while the mass growth is effectively restrained. The results provide a practical and manufacturable design framework for high-performance electromagnetic launch systems.

This paper proposes a multi-sided permanent magnet linear synchronous motor (MSPMLSM) with Ring Structure Winding to meet the high thrust requirements of intelligent circular conveying systems. This motor adopts a three-sided mover structure with three working air gaps: the upper and lower air gaps are composed of parallel permanent magnets and fan-shaped primary teeth, resulting in incomplete primary-mover coupling; the side air gap consists of a Halbach permanent magnet array and arc-shaped primary teeth, leading to uneven air gap length. Firstly, this paper analyzes the magnetic field generated by the special air gap and derives the thrust expression. To simplify the optimization process, the motor is divided into two parts for optimization: Motor I is composed of the side mover and primary, and Motor II is composed of the upper and lower movers and primary. After performing a sensitivity analysis on the main structural parameters of Motor I, a hierarchical optimization is conducted using central composite design (CCD) and box-Behnken design (BBD), and the final parameters are determined using the Non-dominated sorting genetic algorithm II (NSGA-II). For Motor II, the mover parameters are determined through single-objective optimization. Finally, Motors I and II are combined and validated through finite element simulation, with results showing that the new motor significantly improves thrust performance.

Permanent magnet (PM) linear motor is widely used in the electromagnetic launch system due to the merits of high thrust and rapid response. Inheriting the advantages of linear motor, the PM arc-linear motor (PMAM) has been recognized as an eminent competitor for driving servo turntables and large telescope. This article designs a dual-PM excited PMAM (DPM-PMAM) having different PM arrangements and three-unit distributed complementary structure. Benefiting from the special stator-PM layouts, the DPM-PMAM exhibits the essential flux concentration effect, which contributes to enhance the torque capability. The motor topology and working principle of the studied DPM-PMAM are introduced. The feasible stator slot/rotor pole combinations and the major design parameters are optimized for improving electromagnetic performances. Then, the DPM-PMAM is quantitatively compared with the slot-PM excited PMAM (SPM-PMAM) and the yoke-PM excited PMAM (YPM-PMAM) based on the optimal designs. By comparison, it is found that the DPM-PMAM shows the improved average torque and good overload capability. Finally, the 2-D finite-element (FE) predicted results are validated by 3-D FE results.

This paper presents a novel flux-modulated linear motor (FMLM) with Halbach permanent magnet (PM) arrays for rope-less elevator applications. The new structure with iron segments can modulate the magnetic field and serve simultaneously. In addition, Halbach PM arrays in both the outer mover and inner mover are used to increase the output force, machine efficiency and reduce the cogging force. Compared with the conventional counterparts, the proposed FMLM transmits a relatively high force density and low force ripple. Finally, the electromagnetic performance is analyzed quantitatively through finite element analyses (FEA), and the structural parameters of the LM are optimized by the coupling of genetic algorithm (GA) and FEA.

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The purpose of this paperisto present a mathematical model of the magnetic field distribution in planar linear buried permanent-magnet (PM) synchronous motors. The suggested strategy is based on 2D and can be utilized in any slotless linear buried PM machine that has any number of phases, remarkable advantage of buried PMs is high-speed capability due to planar force of zero at motion also, no need of epoxy resin glue to hold despite surface mounted linear PMSMs. The motor uses PDEs for seven regions to formulate its partial differential equations (PDEs): mover-side exterior, mover back iron, PMs, air-gap, winding, stator back-iron and stator-side exterior. Four different magnetization patterns, i.e. parallel, ideal Halbach, 2-segment Halbach and bar magnets in shifting directions magnetization patterns are considered to calculate the tangential and normal components of the open-circuit magnetic flux density, and armature response of the motor below the examination. The winding brings on voltage, flux linkage, self- and mutual inductances, and standard and tangential components of force are computed. The validity of the proposed method is shown by comparing the analytical results with those obtained from 2D finite-element analysis.

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Ironless permanent magnet linear motors (IL-PMLMs) are widely used in high-performance applications due to the advantages of high speed, acceleration, precision, and low wear. By employing the Halbach magnet arrays, the air gap magnetic flux density (MFD) peak can be further improved to obtain greater thrust. However, there is still some thrust ripple during operation, which is caused by the higher harmonics in the air gap MFD. This paper analyzes the effects of Halbach/non-Halbach magnet arrays and stacked/non-stacked winding structures on thrust characteristics of the IL-PMLM by using the FEA method. Finally, two motor schemes with minimum thrust ripple are proposed.