Permanent Magnet Linear Actuator Research Articles

Predictive field-oriented control of three-phase permanent magnet linear synchronous actuators

Predictive field-oriented control of three-phase permanent magnet linear synchronous actuators

High-integrated micro permanent magnet linear actuator positioning system

A tunnel magnetic resistance (TMR) sensor is a magnetic detection sensor with low power consumption and high sensitivity. The TMR sensor has promising applications in the position detection of micro permanent magnet linear actuators since the surrounding magnetic field of the micro actuator in this paper will be changed by its movement. Firstly, according to the air-gap magnetic field distribution characteristics of the micro permanent magnet linear actuator and the detection principle of the TMR sensor, the integrated installation parameters of TMR sensors were determined. Then, with the help of TMR technology, the backpropagation neural network (BPNN) algorithm and improved BPNN using particle swarm optimization (PSO) algorithm were used to study the position identification strategy of the slider, and the algorithm strategy with the minimum error was selected. Finally, the experimental results show that the slider position identification strategy based on the PSO-BPNN algorithm can achieve position tracking error within 0.1 mm under the given step position tracking and sinusoidal position tracking, and the movements can be repeated well.

Electromagnetic Calculation of Tubular Permanent Magnet Linear Oscillation Actuator Considering Corrected Air Gap Permeance

Tubular permanent magnet linear oscillation actuator (TPMLOA), with the simple structure and convenient control, has been paid extensive attention in the field of compressors and industry applications. In this paper, an electromagnetic calculation method of the TPMLOA is proposed. Firstly, an improved topology of the TPMLOA is introduced. Then, based on the radially laminated stator and equivalent magnetic circuit method, the actual air gap length is derived, and the total corrected factor is given. Finally, the electromagnetic characteristic of the TPMLOA is analyzed by 2-D finite-element analysis (FEA) considering the corrected air gap permeance, and the results are compared with normal 2-D FEA and 3-D FEA results. Additionally, a prototype of the TPMLOA is manufactured and tested to verify the accuracy of the calculated results. The comparison results show that the proposed method can quickly and accurately calculate the electromagnetic performance.

Detent Force Reduction Design for the C-Core Single-Phase Permanent Magnet Linear Oscillation Actuator

Single-phase permanent magnet linear oscillation actuators (SP-PMLOAs) have been paid extensive attention in the field of compressors and industry applications. However, the detent force of SP-PMLOA limits the effective stroke and affects the control accuracy of the system. The purpose of this paper is to present a novel C-core SP-PMLOA with double stators arc-teeth and auxiliary slots to reduce detent force. Firstly, the basic structure and dynamic equation of the traditional linear oscillation actuator are introduced. Then, considering the magnetic flux leakage, the detent force formulation is derived by the flux tube method, and a novel structure is presented to reduce detent force and increase the effective stroke by the parametric scan. In addition, the traditional and presented structures of C-core SP-PMLOA are analyzed by 2-D finite element analysis (FEA) mothed. Finally, a prototype is built and tested to verify the results of FEA and calculations. The experimental results show that the presented structure can significantly reduce the detent force and increase the effective stroke.

Determination of Design Parameters Considering Working Harmonic and Irreversible Demagnetization for Flux-Modulated Linear Actuator

This article proposes a design process for a flux modulated (FM) permanent-magnet linear actuator for a five-axis gantry robot system by investigating the parameters affecting working harmonics. A detailed design process using the magnetic gearing effect was developed by considering the magnetic equivalent circuit and finite element analysis models of the FM-linear actuator. Considering natural cooling, the design process includes the effect of irreversible demagnetization when selecting the design parameters. Using the design parameters, a final simulation model was created to check the electromagnetic performance under both no-load and full-load conditions. A prototype was built to validate the results obtained using the proposed analytical model.

Influence of Structural and Physical Parameters on Working Harmonic of Flux-Modulated Linear Actuator for Energy Storage System Fire Hazard Detection Robot

This paper proposes the design and analysis of a flux modulated (FM) permanent magnet (PM) linear actuator for the long track gantry robot system used to detect fire hazards in an electric energy storage system (ESS). A detailed design framework for the FM-linear actuator inspired by the magnetic gearing effect is proposed which includes the selection of slot-pole pair numbers and assigning optimal geometric parameters based on working harmonic characteristics. Using the optimal model, the electromagnetic performances both under no-load and full load conditions are performed to check the feasibility of the actuator for the gantry system. A prototype is built to validate the results obtained using the 2D and 3D finite element analysis (FEA).

Electromagnetic Design of Single-Phase Permanent Magnet Linear Oscillation Actuator Considering Detent Force Minimum

This article proposes an improved tubular single-phase permanent magnet linear oscillation actuator (SP-PMLOA) considering eliminating detent force for direct drive compressor applications. First, the flux tube method and Maxwell stress tensor are used to derive the end force and cogging force formulations based on the magnetic flux leakage of the magnet rings. Then, a novel model with minimum detent force is presented by finite element parametric sweeping. Finally, the electromagnetic performance of the three SP-PMLOAs is compared using 2-D finite element analysis (FEA), whose merits are evaluated, and the thermal distribution of the optimal PMLOA is analyzed using 3-D FEA. The predicted results show that the proposed structure not only can significantly reduce the detent force and the mover axial length but also can increase the thrust force-moving magnet mass ratio.

TUBULAR LINEAR SWITCHED RELUCTANCE ACTUATOR: DESIGN AND CHARACTERIZATION

Linear electromagnetic actuator is receiving significant attention due to recent advances in power electronics and modern control methods. This research proposes a three-phase tubular linear switched reluctance actuator (LSRA) for application in the semiconductor fabrication industry. The tubular LSRA has a robust construction, low manufacturing and maintenance cost, good fault tolerance capability, and high reliability in a harsh environment, making it an attractive alternative to a permanent magnet linear actuator. However, the tubular LSRA has a long mover, which increases the possibility of the mover deforming during fabrication. So, a new mover design is proposed to overcome the problem. The proposed mover design allows the traveling distance of the actuator to be modified by adding or removing the rings without changing the shaft. The tubular LSRA prototype is fabricated according to the optimized design. To drive the tubular LSRA, a appropriate switching algorithm method are used to provide the correct switching signal. This method is straightforward, while no extensive knowledge of power electronic converter is required. The developed tubular LSRA can generate a maximum static force of 0.65N. Through the open-loop reciprocating motion, the dynamic responses of the tubular LSRA can achieve a maximum velocity of 210mm/s and maximum acceleration of 8m/s2, which are in the performance range for precision mechanism.

Design of Large-Stroke and High-Resolution Drive System Based on Giant Magnetostrictive Material

A novel macro–micro linear actuator based on the giant magnetostrictive material has been proposed to achieve high precision and large-stroke. This structure uses a permanent magnet drive coil structure, and a new cylindrical structure permanent magnet linear actuator is made according to the principle of Lorentz force. The permanent magnet and the shell form stator part, and the giant magnetostrictive actuator (GMA) structure is embedded in the interior as a mover structure to achieve macro-motion displacement; the micro-motion can be realized by controlling the GMA. The micro-motion component and the macro-motion component can always remain coaxial in structure and integrated on a motor structure. The actuator’s output displacement can be adjusted by controlling the macro/micro coil current. Experimental results indicate that the macro-displacement can be up to 30 mm, and the response time is below 0.2 s. The micro-motion positioning accuracy can reach nanometer level, which has the advantages of simple structure and easy installation with coaxial, and has a broad application prospect in the field of precision manufacturing.

Modeling and Decoupling Control of a Linear Permanent Magnet Actuator Considering Fringing Effect for Precision Engineering

In this article, accurate modeling and decoupling control of a linear ironless PM actuator are implemented for precision engineering. Given the fringing effect due to the finite length, the magnetic field of the PMs and the three-phase winding are both calculated by applying an improved Fourier series expansion. Subsequently, based on a distributed model, the associated flux linkage and winding inductances are obtained and validated. Compared with rotary motors of physical symmetry, the winding inductance matrix makes the electrical model of the finite-long linear actuator present a new non-uniform form, to which the classic decoupling technique is inapplicable directly. Therefore, improved decoupling strategies are established utilizing the zeroth-order approximation of the inductances based on the $dq0$ transformation, as well as a real-time updating scheme. Physical experiments show that high-order harmonics are eliminated by applying the non-uniform model, which makes it effective and applicable.

Two-Phase Linear Hybrid Reluctance Actuator with Low Detent Force

In this paper, a novel two-phase linear hybrid reluctance actuator with the double-sided segmented stator, made of laminated U cores, and an interior mover with permanent magnets is proposed. The permanent magnets are disposed of in a way that increases the thrust force of a double-sided linear switched reluctance actuator of the same size. To achieve this objective, each phase of the actuator is powered by a single H-bridge inverter. To reduce the detent force, the upper and the lower stator were shifted. Finite element analysis was used to demonstrate that the proposed actuator has a high force density with low detent force. In addition, a comparative study between the proposed linear hybrid reluctance actuator, linear switched reluctance, and linear permanent magnet actuators of the same size was performed. Finally, experimental tests carried out in a prototype confirmed the goals of the proposed actuator.

Multi-Fidelity Design Optimisation of a Solenoid-Driven Linear Compressor

Improved management and impermeability of refrigerants is a leading solution to reverse global warming. Therefore, crank-driven reciprocating refrigerator compressors are gradually replaced by more efficient, oil-free and hermetic linear compressors. However, the design and operation of an electromagnetic actuator, fitted on the compression requirements of a reciprocating linear compressor, received limited attention. Current research mainly focuses on the optimisation of short stroke linear compressors, while long stroke compressors benefit from higher isentropic and volumetric efficiencies. Moreover, designing such a system focuses mainly on the trade-off between number of copper windings and the current required, due to the large computational cost of performing a full geometric design optimisation based on a Finite Element Method. Therefore, in this paper, a computationally-efficient, multi-objective design optimisation for six geometric design parameters has been applied on a solenoid driven linear compressor with a stroke of 44.2 mm. The proposed multi-fidelity optimisation approach takes advantage of established models for actuator optimisation in mechatronic applications, combined with analytical equations established for a solenoid actuator to increase the overall computational efficiency. This paper consists of the multi-fidelity optimisation algorithm, the analytic model and Finite Element Method of a solenoid and the optimised designs obtained for optimised power and copper volume, which dominates the actuator cost. The optimisation results illustrate a trade-off between minimising the peak power and minimising the volume of copper windings. Considering this trade-off, an intermediate design is highlighted, which requires 33.3% less power, at the expense of an increased copper volume by 5.3% as opposed to the design achieving the minimum copper volume. Despite that the effect of the number of windings on the input current remains a dominant design characteristic, adapting the geometric parameters reduces the actuator power requirements significantly as well. Finally, the multi-fidelity optimisation algorithm achieves a 74% reduction in computational cost as opposed to an entire Finite Element Method optimisation. Future work focuses on a similar optimisation approach for a permanent magnet linear actuator.

Modeling, Design Optimization, and Verifications of Permanent Magnet Linear Actuators for Structural Vibration Mitigation Applications

Structural vibrations in modern buildings have been increasing concerns. If not properly controlled, they would give rise to serviceability problems and disturbances to occupants. The permanent magnet (PM) linear actuator-based active vibration mitigation strategy exhibits excellent dynamic performances on elimination of vibrations with complex modes, and has great potential. This paper describes modeling, design optimization, and numerical and experimental verifications of a PM linear actuator for structural vibration mitigation applications. Analytical expressions for prediction of the actuator performance are derived, and the linear actuator is then designed in optimization within a specific set of volumetric and thermal constraints in order to maximize the product of efficiency and power factor. It is shown that the proposed analytical model has provided a computationally efficient tool for design optimization, and the Halbach ratio and actuator width have significant impacts on the performance of the PM linear actuator. The results are validated by finite-element computations, and further verified by experimental measurements on a prototype actuator.

Optimization of an Electrodynamic Linear Actuator for Biometric Applications

This paper describes the configuration of a permanent magnet linear actuator for biometric applications and explains the basics of the methodology used to evaluate the actuator thrust. The methodology, based on analytical expressions of the magnet flux linkage, enables a fast and accurate evaluation of the axial force and can apply to any set of coaxial coils. The formulations are used to optimize the actuator configuration, in order to improve the thrust uniformity along the mover stroke, some technological design fulfilling some technological design constraints. Introducing an auxiliary set of coaxial coils, the optimization procedure enables a remarkable uniformity improvement. The results are verified by finite-element analyses, and the measurements performed on a prototype confirm the effectiveness of the design procedure.

Electromagnetic Linear Microdrive for Braille Screen: Control and Circuit Test

Graphical interfaces based on visual representation and direct manipulation of objects make the adequate use of computers quite difficult for people with reduced sight. A new type of graphical Braille screen is developed. Permanent magnet linear actuator intended for driving a needle in Braille screen has been optimized. The recently developed permanent magnet linear electromagnetic actuator for driving a needle in a Braille screen and the circuit testing method using micro r obots are discussed. Also, a planar and spatial motion tactile display with incorporated electromagnetic linear drives into its links is designed. The optimization is carried out with respect to minimal magnet motive force ensuring required minimum electromagnetic force on the mover. The optimization factors include dimensions of the cores and movable parts under additional constraint for overall dimension of the actuator. Finite element analysis, response surface methodology and design of experiments have been employed for the optimization. The static force characteristics and magnetic field distribution is studied when varying the parameters. 

Winding distribution characteristic of slot-less tubular permanent magnet linear actuator and its experiment

Winding distribution characteristic of slot-less tubular permanent magnet linear actuator and its experiment

Comparative investigation of permanent magnet linear oscillatory actuators used in orbital friction vibration machine

The paper describes the alternative designs and performances of a single-phase moving-magnet linear oscillating actuator (LOA) which has been developed for orbital friction welding. The influences of the pole ratio on the performance of the LOAs are investigated and the optimal parameters have been identified with reference to the thrust force characteristics. It can be illustrated that a quasi-Halbach magnetized LOA, in which the magnets are assembled on a nonmagnetic mover yoke, represents the best electromagnetic performances. Finally, the predicted thrust force-current characteristic of quasi-Halbach magnetized LOA is validated by measurements on a prototype actuator.

Temperature distribution in multi domain construction of the permanent magnet linear actuator

Abstract The transient thermal model of the permanent magnet linear actuator (PMLA) has been considered. The characteristics of heating have been calculated including the main subdomains of the actuator. The carcasses from various materials have also been considered. The calculations have been verified experimentally and a good conformity was obtained.

Modeling and Evaluation of Linear Oscillating Actuators

The operation of linear oscillating system is complicated, involving system nonlinearities of both actuator and load, and variations of driving frequency in order to track the mechanical resonance. In this paper, both analytical and state-variable modeling techniques are used to investigate the influence of actuator parameters, such as back-emf/thrust force coefficient and cogging force, on the performance of linear oscillating systems. Analytical derivations are validated by simulations, and good agreements are achieved. The findings of the paper can greatly facilitate the design and evaluation processes of permanent magnet linear actuators.

Testing and experimental characterization of a linear permanent magnet actuator for active vehicle suspension

This paper describes the testing and experimental characterization of a linear permanent magnet actuator, which is designed and developed for active vehicle suspension, under both static and dynamic conditions. Since the active suspension unit operates over a wide force-velocity range with varying duty ratios, it is essential to establish an effective thermal model which can be used for assessing temperature rise of the actuator under various operating conditions. The temperature rise of the actuator is measured and the results are compared with the prediction by the derived transient thermal model. It is shown that the measured actuator parameters and characteristics are closed to their predicted values. The linear actuator is controlled by a dSPACE system via a three phase inverter and its velocity tracking performance is presented.