Linear Reluctance Research Articles

Reluctance Based Actuator for Discrete Machine Hammer Peening

In machine hammer peening, an actuator system moves a ram in oscillating motion, which is oriented in angular position, preferably perpendicular, to a workpiece surface. On the tip of the ram, a hammer head with application specific shapes can be mounted. The hammer head is moved across the targeted workpiece surface area by means of a machine tool or an industrial robot. The impacts in defined patterns enable modifications of the surface integrity like smoothing the surface roughness or increasing fatigue strength by induced compressive residual stresses. This paper presents a novel DC-driven actuator system using a highly dynamic short-stroke linear reluctance motor to provide a time or trigger controlled hammer head movement including a system for process monitoring. In contrast to conventional systems, Deterministic Impact Peening (DIP) can be realized by position or speed related triggering of the impacts. The reluctance-based actuator with its geometrically optimized mechatronic system design provides performance characteristics favorable to known machine hammer peening systems. The position-controlled triggering of the hammer head is able to achieve uniform or defined local elastoplastic deformations on the workpiece surface, thus resulting in deterministic residual stress distributions.

Quantitive Harmonic Analysis and Force Ripple Suppression of a Parallel Complementary Modular Linear Reluctance Machine

Considering the fluctuating price of permanent magnet, magnetless machine is a new trend in development. Variable reluctance linear machines (VRLM) with simple structure, good robustness, and high dynamic performance, is one of the potential candidates for linear direct-drive wave energy conversion (WEC) application replacing PM-excited linear machine. To ameliorate the fault-tolerance performance of VRLM, the researchers have come up with modular or segmented design, denoted as modular variable reluctance linear machines (MVRLM) However, suffering from large thrust ripple, the design of MVRLM still needs to be improved. To relieve the force ripple of MVRLM, a novel H-shaped modular variable-flux linear reluctance machine (HMVF-LRM) is proposed in this paper. The principle of force ripple suppression by using parallel-complementary structure is analyzed deeply. In this paper, the analytical calculation of induced voltage is developed quantitively with equivalent magnetic circuit method (EMC) and harmonics analysis. Then the design mechanism of HMVF-LRM is illustrated. Further, the performance and fault-tolerant capability of the proposed machine are simulated and evaluated by finite element analysis (FEA), and the prototype is tested to verify the effectiveness of the machine design.

Precision Flux Control of Linear Reluctance Actuator Using the Integral Sliding Mode Method

The performance of the actuator is becoming increasingly important in the ultra-precision stage. However, the traditional Lorentz motors with given mechanical parameters cannot provide enough force for the next-generation motion stage in the semiconductor industry since they achieve a physical limit of power factor. To tackle this problem, this study develops a novel-driven approach and its control strategy for high-dynamic stages. Explicitly, the proposed method utilizes a linear reluctance motor as an actuator, which could promote the continuous thrust significantly. A heuristic optimization-based Bouc–Wen model is established to describe the nonlinear behavior of the novel actuator. Also, a flux control algorithm based on the integral sliding mode is derived and adjusted for precision thrust generation. Comparative simulations on a specific linear reluctance motor confirm the effectiveness and superiority of the proposed method and show that it has the ability to conquer the force nonlinearity of the novel actuator.

Electrotechnical complex of maglev rolling stock

Background: The development of work in the field of creating cargo maglev transport systems is associated with the development and study of the electro technical complex of the rolling stock for the operating range with long stretches in poorly developed territories.
 Aim: The aim of the work is to substantiate the structure and parameters of the components of the electro technical complex of the rolling stock, to study the operating modes.
 Methods: The main research methods are functional structural analysis and synthesis, computer modeling, computational studies, analysis of research results.
 Results: As a result of the research, the factors that determine the appearance of the electrotechnical complex of the rolling stock have been identified. The basic requirements for the electrical complex are formulated. The structure was developed and the parameters of the components of the electrical complex for the transport platform with magnetic levitation were determined. A high-speed flat car model 13-6990 for the transportation of containers was chosen as the closest railway analogue. A computer model of a combined traction-levitation system based on a linear reluctance inductor motor has been developed. The results of computational studies, confirming the physical feasibility of the electrical complex of the rolling stock with linear reluctance inductor motors, are presented.
 Conclusion: The practical significance lies in the fact that the proposed concept of constructing an electro technical complex of rolling stock provides for the creation of a maglev transport system with a low-cost infrastructure.

A Study on Design of Tubular Linear Reluctance Generator Taking Account of Leakage Elements

The focus of the work demonstrates the validation of the new shape translator taking account of leakage elements in linear oscillating generator for a series hybrid electric vehicle. By comparison and analysis using the various shapes of translator teeth, it is studied to minimization of the force ripple and increasing useful magnetic flux by equivalent magnetic circuit (EMC) and finite element method (FEM). It will be analyzed considering the leakage reluctances for a more practical and effective analysis, and design process of tubular linear reluctance generator. At last, the trapezoidal shape of translator is selected as optimal model among the proposed translator teeth in tubular linear reluctance generator. The results of this study will give elaborate information about the design rules and the performance data of linear gensets.

Linear Hybrid Reluctance Motor with High Density Force

Linear switched reluctance motors are a focus of study for many applications because of their simple and sturdy electromagnetic structure, despite their lower thrust force density when compared with linear permanent magnet synchronous motors. This study presents a novel linear switched reluctance structure enhanced by the use of permanent magnets. The proposed structure preserves the main advantages of the reluctance machines, that is, mechanical and thermal robustness, fault tolerant, and easy assembly in spite of the permanent magnets. The linear hybrid reluctance motor is analyzed by finite element analysis and the results are validated by experimental results. The main findings show a significant increase in the thrust force when compared with the former reluctance structure, with a low detent force.

Design and Control for Linear Machines, Drives, and MAGLEVs—Part I

The 18 papers in this special section focus on the technology of linear electric (electromagnetic)machines (LEMs). LEMs were introduced at the turn of the last century. They have been conceived to convert electrical energy into mechanical energy (or vice versa) as a direct linear motion through electromagnetic forces. LEMs are reversible devices,meaning that they can work as bothmotors and generators. Although feasible, linear alternators are currently explored for limited applications (e.g., Stirling motor). On the contrary, linear motors or actuators are electromagnetic devices capable of producing direct (without any link or interposition) linear motions of the following types: in a unique direction, short-stroke motion, oscillatory motion, and step-by-step motion. Correspondingly, exactly as in the rotating counterpart, different types of linear motors have been devised: linear synchronous motors (LSMs) in its versions with excitation winding, with permanent magnets (PMs) LSMs or without both (linear reluctance motor = LRM), linear induction motors (LIMs), and linear stepper motors.

A Superconducting Linear Variable Reluctance Machine for Urban Transportation Systems

This paper presents a new superconducting linear variable reluctance machine for urban transportation applications. The proposed linear machine has a doubly salient structure. Its armature adopts segmented configuration and houses both the copper armature winding and the high-temperature superconducting field winding, while the salient-pole rail consists of iron core only with no excitation sources. Performances of the proposed machine are analyzed and evaluated by the finite element method. By using segmented armature design, the force ripple can be suppressed to 5.5% that is very desirable for urban transportation systems.

FORCE CHARACTERIZATION OF A TUBULAR LINEAR ELECTROMAGNETIC ACTUATOR USING FINITE ELEMENT ANALYSIS METHOD (FEM)

This paper presents an extensive characterising study of two novel electromagnetic actuators, each with different constructions and characteristics aiming to analyse the behaviour and output characteristics of the two designs. The two actuators are Tubular Linear Reluctance Actuator (TLRA) and Tubular Linear Permanent magnet (TLPM) with Halbach array actuator. The study covered the variation of three parameters, which are the actuator air gap, number of turns and actuator size. A comparative section was also presented for the purpose of comparison. The study concentrated extensively on the two characteristics of both actuators known as output thrust force and working range as they are considered as two main concerns of any actuator design. The simulation was used to show the differences between the two designs in many design aspects such as force, displacement and effects of parameters variations. The applied simulation was performed using 3D Finite-element Ansys software, which is capable of showing the magnetic field distribution in the whole actuator and predicting the strength and length of the output stroke.

Performance Characteristics and Preliminary Analysis of Low Cost Tubular Linear Switch Reluctance Generator for Direct Drive WEC

This paper presents the performance characteristics of a low cost but high-power density tubular linear switch reluctance generator (TLSRG) for direct drive marine wave energy conversion (WEC). The presented TLSRG consists of series of soft magnetic rings and exhibits higher power density than conventional teeth type TLSRG. There is sole set of round winding in each stator slot, which facilitates manufacturing process, thus, results in low cost. The referred ring segments are both magnetically and electrically isolated with each other so it reduces the phase coupling and increase the capability of fault tolerance that is favorable to be used in harsh conditions as WEC. The characteristics and dynamic performance at WEC mode are examined and discussed, validating that the presented TLSRG is a strong alternative candidate to permanent magnet tubular generator for WEC.

Design and analysis of EI core structured transverse flux linear reluctance actuator

In this study, an EI core linear actuator is proposed for horizontal movement systems. It is a transverse flux linear switched reluctance motor designed with an EI core structure geometrically. The actuator is configured into three phases and at a 6/4 pole ratio, and it has a stationary active stator along with a sliding passive translator. The stator consists of E cores and the translator consists of I cores. The actuator has a yokeless design because the stator and translator have no back iron. The E and I cores are separated from each other to provide a fault-tolerant design and decrease the weight. The proposed model is analyzed by 3D finite element method. Phase inductance, flux linkage, and axial forces are examined by magnetostatic finite element analysis and verified by analytical approximations and experimental results. Under DC 8 A phase excitation, propulsion force is 72.57 N and corresponding power consumption is 115.5 W. This has advantages for horizontal movement systems.

Analyses of the effect of length difference between plunger and winding on tubular linear reluctance motor performance

SUMMARY Length difference between plunger and winding is one of the most important issues in Tubular Linear Reluctance Motor (TLRM) design. Determining appropriate plunger length can have effect on TLRM output parameters, i.e. plunger speed, magnetic force and efficiency. In this paper, dynamic models of TLRM in two different conditions, i.e. equal and unequal length, using electrical and mechanical equations are proposed. Afterwards, the dynamic models of two conditions are simulated. The comparison of simulation results would determine the appropriate plunger length. Finally, in order to validate the modeling results, simulation and experimental results are compared. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of Internal Water Pressure on the Measured Coefficient of Thermal Expansion of Concrete

A study was conducted to evaluate the effect of coefficient of thermal expansion (CTE) test procedures and length-change measuring devices on the measured CTE values. Twenty different coarse aggregate sources were tested using the Texas Department of Transportation (TxDOT) and the American Association of State Highway and Transportation Officials (AASHTO) suggested CTE methods. Two different types of length-change measuring devices, linear variable differential transformers (LVDTs) and differential variable reluctance transducers (DVRTs), were used. No significant effects of length-change measuring devices were observed on the CTE values measured by the TxDOT method. However, the test methods have shown effects on the measured values. The TxDOT method yields higher CTE values than the AASHTO method. Data obtained in this study confirmed that the internal water pressure development during the heating and cooling cycles is one of the potential reasons. Internal water pressure can significantly affect the CTE of concrete. Further investigation is needed to determine the effect of internal water pressure on the CTE, which affects the design and service life of concrete pavements.

Design and Analysis of a Flux-Controllable Linear Variable Reluctance Machine

This paper proposes a linear variable machine equipped with a set of field winding which is capable for adjusting the air-gap flux. As conventional variable reluctance machines, the proposed machine has a doubly salient structure and no permanent magnets or windings on the mover. The distinct feature of the proposed machine is that there are both the ac armature winding and the dc field winding in the stator. By inviting the dc field winding, the proposed machine not only has the flux control capability, but also realizes the bipolar operation. In this paper, the proposed machine design and its operating principle are presented and discussed. Then, a two-phase machine in modular design is dimensioned. By using the three-dimensional finite element analysis, both the steady and transient performances are quantitatively analyzed and evaluated.

Sensorless load and position estimation in linear reluctance actuator

Sensorless load and position estimation of linear reluctance actuator is investigated in this paper. Due to wide application of these actuators in several industrial automation systems, sensorless techniques are significant to decrease the cost of the system and increase the reliability in the closed-loop control systems. In this paper, based on dynamic model of the actuator and the characteristics of its subsystems, the possibility of sensorless estimation of mechanical parameters is explored. Considering nonlinear behavior of magnetic subsystem, the position of the plunger could be estimated based on the winding inductance and the excitation current value. Then, the amount of load force could be determined based on current value and estimated position. Laboratory measurements of the actuator’s characteristics assist in increasing the accuracy of estimation besides dynamic modeling.

Comparison of a High Thrust Force Density Segmental Stator Linear Switch Reluctance Machine for with Different Topologies

Linear switch reluctance machine (LSRM) has been an alternative to linear permanent magnet synchronous machine and linear induction machine. However, the nature of reluctance force production, together with the air gap which is always much larger than rotary SRM, result in low propulsion force density in LSRM. This is an inherent demerit of LSRM, limiting its applications where the machine size is strictly set. This paper presents a novel linear switch reluctance machine with segmental stator, which consists of series of ferrite-magnetic segments. The principle of the proposed LSRM featuring high force density has been introduced. A variety of topologies of the proposed machine have been presented including single stator, dual stator and non-stator yoke structure. This paper deals with the comparison of the proposed segmental stator linear switch reluctance machine and traditional teeth type linear reluctance machine in terms of the propulsion force, normal force and force ripple as well as the force density and active pay load ratio. Finite Element Method is implemented to obtain the correlated results. Some conclusions are drawn to verify the analysis above.

Analysis and Performance Evaluation of a High Thrust Force Density Segmental Stator Linear Switch Reluctance Machine for Low Cost Conveyor Applications

This paper presents a novel linear switch reluctance machine (LSRM) with segmental stator. The principle of the presented machine is given and compared to the well-known teeth type linear switch reluctance machine. Because the presented machine incorporates a simple concentric winding and concrete ferrite-magnetic segmentations, it features unique magnetic circuit compared to teeth type linear reluctance machine. It is found that the presented linear reluctance machine gains favorable superiority over the teeth type linear reluctance machine in terms of high force density, high reliability and low cost. Different topologies of the presented machine are given and both their merits and demerits are discussed.

Development of a Segmented Linear Variable Flux Reluctance Motor with DC-Field Coil

This paper proposes a new type of linear motor based on the concept of variable flux reluctance motor (VFRM). By adopting segmented primary stator, the segmented linear VFRM (SLVFRM) can eliminate asymmetry between phases due to end-effect. Meanwhile, multi-phase SLVFRM of any number of phases can be obtained by adjusting number of segments directly. The stator/mover tooth pitch combination and segments arrangement rules are also illustrated. An optimized 3-phase SLVFRM is analyzed by finite element analysis, with focus on characteristics such as cogging force, back-EMF and winding inductances. Further, both brushless AC (BLAC) and brushless DC (BLDC) drive for SLVFRM are investigated. Besides much smaller force ripple, BLDC drive can obtain higher average force at same RMS current due to trapezoidal back-EMF. The force characteristicwith variousAC and DC currents and current angles are also investigated in the paper, and it shows that SLVFRM has negligible reluctance force while keeping the same AC and DC currents is optimal for maximum efficiency operation under a fixed copper loss.

Model of dynamic operation of stepper linear reluctance motor based on field approach

PurposeThe aim of this paper is to analyse the influence of various methods of controlling a stepper linear reluctance motor on the dynamic parameters of this motor.Design/methodology/approachConstruction, principle of working, and mathematical model of a four‐band stepper linear reluctance motor are shortly discussed. In order to elaborate an effective tool for motor performance analysis, a circuital approach was applied. To increase model accuracy, major parameters of the model (main self‐ and leakage inductances) were calculated on the basis of a 3D electromagnetic field distribution using Finite Element Method (FEM). The nonlinearity of the core was taken into account. Elaborated mathematical model was implemented in MatLab‐Simulink environment. Selected results of investigations are presented.FindingsThe elaborated mathematical model and the review of control methods are very useful for analysis of dynamic operation of stepper linear reluctance motors.Originality/valueThe paper provides a review of control methods of stepper linear reluctance motors.

Measurement method for determining the magnetic hysteresis effects of reluctance actuators by evaluation of the force and flux variation

A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator.