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1 – 10 of 35Thomas S. Parel, Mihai D. Rotaru, Jan K. Sykulski and Grant E. Hearn
The purpose of this paper is to optimise the cost‐based performance of a tubular linear generator and to minimise cogging forces.
Abstract
Purpose
The purpose of this paper is to optimise the cost‐based performance of a tubular linear generator and to minimise cogging forces.
Design/methodology/approach
Optimisation of a tubular linear generator with longitudinal flux topology has been undertaken using a finite element method. The computational models used have been verified experimentally.
Findings
The use of an oversized stator linear generator design as opposed to an oversized translator design has the potential to increase the output electromotive force per unit material cost by 25 per cent for slotless iron core topologies and approximately 14 per cent for air core topologies. For cogging force minimisation, optimisation of the length of the stator core is an effective technique for both oversized stator and oversized translator constructions. Comparisons of magnet materials also indicate that the higher cost of rare earth magnets to ferrites is compensated by their superior specific performances.
Originality/value
In this paper, a broader range of design parameters than in previous investigations has been optimised for the slotless iron core and air core topologies. The result relating to cogging force reduction and cost savings (in particular) has the potential to make direct drive wave energy extraction a more competitive technology in terms of reliability and cost.
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Jikai Si, Zuoguang Yan, Rui Nie, Shuai Xu, Chun Gan and Wenping Cao
To improve the power density and generation efficiency of the tubular permanent magnetic linear generators (TPMLGs) under realistic sea-stator condition, a TPMLG with 120° phase…
Abstract
Purpose
To improve the power density and generation efficiency of the tubular permanent magnetic linear generators (TPMLGs) under realistic sea-stator condition, a TPMLG with 120° phase belt toroidal windings (120°-TPMLG) for wave energy conversion is proposed in this paper.
Design/methodology/approach
First, the structure of the 120°-TPMLG is introduced and its operation principle is analyzed. Second, the design process of the 120°-TPMLG is described. Meanwhile, the finite-element models of the 120°-TPMLG and the TPMLG with traditional fractional pitch windings (T-TPMLG) are established based on the similar overall dimensions. Then, the electromagnetic characteristics of the 120°-TPMLG are analyzed, such as air gap flux density, back electromotive force and load voltage. Finally, a comparative analysis of the magnetic flux density, flux linkage, load and no-load performance of the two generators are conducted.
Findings
The result shows that the 120°-TPMLG has higher power density and generation efficiency than the T-TPMLG.
Originality/value
This paper proposes a TPMLG with 120° phase belt toroidal windings (120°-TPMLG) to improve the power density and generation efficiency.
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Danson M. Joseph and Willem A. Cronje
The purpose of this paper is to present a double‐sided tubular linear machine layout direct‐drive applications, with particular focus on wave‐energy conversion. The paper…
Abstract
Purpose
The purpose of this paper is to present a double‐sided tubular linear machine layout direct‐drive applications, with particular focus on wave‐energy conversion. The paper documents both the computational and mathematical analysis of this novel machine layout.
Design/methodology/approach
The selection and finite‐element optimisation of the permanent‐magnet array is presented. The machine is then modelled using magnetic circuit theory. By simultaneously solving the system of equations, a demonstrative design is developed and simulated so as to validate the mathematical model and compare the performance of the new layout with a traditional layout.
Findings
A surface‐mounted magnetic array, with unshaped‐poles, is most suitable for the proposed layout. The mathematical model exhibits a suitable level of accuracy for design and analysis purposes. The calculated resultant force differs from the FEA calculation by 1.85 per cent. A higher force‐density is exhibited by the proposed layout, when compared with flat layouts, with a reduction of 36.5 per cent in the spatial footprint and magnetic material of the machine.
Research limitations/implications
Although the research is focused on the application of wave‐energy conversion, the techniques are application‐independent. However, certain design decisions should be reviewed for other applications.
Practical implications
The practical implementation of such a machine poses many mechanical obstacles. These have been solved in theory, and are being implemented at the time of writing.
Originality/value
The combination of a double‐sided and a tubular layout has not previously been researched. This research fills that void and provides designers with the technical background and a mathematical model for development of such devices.
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Andrzej Demenko, Ernest Mendrela and Wojciech Szeląg
The aim of the paper is to find the simple and accurate model for the analysis of a drive with a tubular linear permanent magnet machine (TLPMM). Attention is paid to the models…
Abstract
Purpose
The aim of the paper is to find the simple and accurate model for the analysis of a drive with a tubular linear permanent magnet machine (TLPMM). Attention is paid to the models that take into account the saturation effects and is useful in the calculations of electromagnetic forces.
Design/methodology/approach
A circuit model and a field‐circuit model (FCM) are considered. The FCM includes finite element (FE) formulation for the axisymmetric electromagnetic field, equations which define the connections of windings and converter elements, and expressions that describe the control system. The FE method is used to determine the parameters of the circuit model. In order to simplify the circuit model, saturation effects caused by armature reaction are ignored. The electromagnetic force calculation is based on the virtual work principle and uses an approximate expression for the derivative of system co‐energy. The results obtained for the proposed models have been compared.
Findings
The proposed FE method of force calculation conforms with the applied method of movement simulation. For the rotor position when the cogging force is equal to zero the calculated cogging force is “almost” zero within seven‐decimal‐place accuracy. The effects of armature reaction on the performance of a TLPMM machine are similar to those which occur in a classical DC machine; in particular the demagnetising effect caused by saturation is observed.
Originality/value
The paper shows the influence of the saturation effects on the electromagnetic force of a TLPMM. In the case of “strong saturation”, the classical circuit model may be inappropriate for engineering calculations.
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Ana Paula Zanatta, Ben Hur Bandeira Boff, Paulo Roberto Eckert, Aly Ferreira Flores Filho and David George Dorrell
Semi-active suspension systems with electromagnetic dampers allow energy regeneration and the required control strategies are easier to implement than the active suspensions are…
Abstract
Purpose
Semi-active suspension systems with electromagnetic dampers allow energy regeneration and the required control strategies are easier to implement than the active suspensions are. This paper aims to address the application of a tubular linear permanent magnet synchronous machine for a semi-active suspension system.
Design/methodology/approach
Classical rules of mechanics and electromagnetics were applied to describe a dynamic model combining vibration and electrical machines theories. A multifaceted MATLAB®/Simulink model was implemented to incorporate equations and simulate global performance. Experimental tests on an actual prototype were carried out to investigate displacement transmissibility of the passive case. In addition, simulation results were shown for the dissipative semi-active case.
Findings
The application of the developed model suggests convergent results. For the passive case, numerical and experimental outcomes validate the parameters and confirm system function and proposed methodology. MATLAB®/Simulink results for the semi-active case are consistent, showing an improvement on the displacement transmissibility. These agree with the initial conceptual thoughts.
Originality/value
The use of linear electromagnetic devices in suspension systems is not a novel idea. However, most published papers on this subject outline active solutions, neglect semi-active ones and focus on experimental studies. However, here a dynamic mechanical-electromagnetic coupled model for a semi-active suspension system is reported. This is in conjunction with a linear electromagnetic damper.
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Liang Yan, Lei Zhang, Zongxia Jiao, Hongjie Hu, Chin-Yin Chen and I-Ming Chen
Force output is extremely important for electromagnetic linear machines. The purpose of this study is to explore new permanent magnet (PM) array and winding patterns to increase…
Abstract
Purpose
Force output is extremely important for electromagnetic linear machines. The purpose of this study is to explore new permanent magnet (PM) array and winding patterns to increase the magnetic flux density and thus to improve the force output of electromagnetic tubular linear machines.
Design/methodology/approach
Based on investigations on various PM patterns, a novel dual Halbach PM array is proposed in this paper to increase the radial component of flux density in three-dimensional machine space, which in turn can increase the force output of tubular linear machine significantly. The force outputs and force ripples for different winding patterns are formulated and analyzed, to select optimized structure parameters.
Findings
The proposed dual Halbach array can increase the radial component of flux density and force output of tubular linear machines effectively. It also helps to decrease the axial component of flux density and thus to reduce the deformation and vibration of machines. By using analytical force models, the influence of winding patterns and structure parameters on the machine force output and force ripples can be analyzed. As a result, one set of optimized structure parameters are selected for the design of electromagnetic tubular linear machines.
Originality/value
The proposed dual Halbach array and winding patterns are effective ways to improve the linear machine performance. It can also be implemented into rotary machines. The analyzing and design methods could be extended into the development of other electromagnetic machines.
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Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines;…
Abstract
Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.
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Guozhen Zhang, Rui Nie, Jikai Si, Xiaohui Feng and Changli Wang
This study aims to unveil the generation mechanism of the thrust force in a tubular flux-switching permanent magnet (PM) linear (TFSPML) machine; the operation principle of the…
Abstract
Purpose
This study aims to unveil the generation mechanism of the thrust force in a tubular flux-switching permanent magnet (PM) linear (TFSPML) machine; the operation principle of the TFSPML machine is analyzed.
Design/methodology/approach
First, the air-gap flux density harmonic characteristics excited by PMs and armature windings are investigated and summarized based on a simple magnetomotive force (MMF)-permeance model. Then, the air-gap field modulation theory is applied in analyzing the air-gap flux density harmonics that contribute to the electromagnetic force. In addition, a simple method for separating the end force of the TFSPML machine is proposed, which is a significant foundation for the comprehensive analysis of this type of machine. As a result, the operation principle of the TFSPML machine is thoroughly revealed.
Findings
The analysis shows that the average electromagnetic force is mainly contributed by the air-gap dominant harmonics, and the thrust force ripple is mainly caused by the end force.
Originality/value
In this paper, the operation principle of the TFSPML machine is analyzed from the perspective of air-gap field modulation.
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Nobuyuki Naoe and Akio Imazawa
This paper aims to present a Halbach magnet array linear machine, without an iron core and the electromotive force (EMF) characteristic results.
Abstract
Purpose
This paper aims to present a Halbach magnet array linear machine, without an iron core and the electromotive force (EMF) characteristic results.
Design/methodology/approach
The linear machine was made with mover coils and a permanent magnet stator without an iron core. For an outline design, the analyzed magnetic density results were compared to the Halbach array with a horizontal array using the 3D finite element analysis. The test was carried out on an experimental system using a prototype linear machine. The EMF of the linear machine, with applied Halbach array magnetic circuit, is verified with the experiment.
Findings
The EMF peak value of the Halbach array is larger than the EMF of the horizontal array. Compared to the EMF in the experimental results, the effective value of the Halbach array is 1.69 times greater at an average operation speed of 373 mm/s.
Originality/value
The core-less linear machine has advantages of reduced cogging torque and iron loss because both the stator and the mover do not have an iron core. The stator and rotor will not rust from water. In this paper, it is clear from the basic electrical characteristics that the linear machine, with applied Halbach array, is larger than the EMF of the horizontal array.
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Sumeet Khalid, Faisal Khan, Zahoor Ahmad and Basharat Ullah
For compactness and ease in assembling, a novel miniature size tubular moving magnet linear oscillating actuator (MT-MMLOA) design for miniature linear compressor application is…
Abstract
Purpose
For compactness and ease in assembling, a novel miniature size tubular moving magnet linear oscillating actuator (MT-MMLOA) design for miniature linear compressor application is proposed in this paper.
Design/methodology/approach
This MT-MMLOA design possesses a modular C-core stator structure having separation at the middle. Axially magnetized tubular permanent magnets are accommodated on the mover. To improve the output parameters of the linear oscillating actuators (LOA), all the design parameters are optimized using a parametric sweep. Finite element analysis of the proposed design is performed to examine the magnetic flux density as well as thrust force under both static and dynamic analysis within the intended stroke range.
Findings
Compared to conventional LOA for miniature compressors, the motor constant of the proposed LOA is 37 N/A that is 85% greater while keeping the same size of LOA. Permanent magnet volume used in the investigated topology of LOA is 26% reduced. Additionally, the overall volume of the machine is 10.3% decreased. Furthermore, the proposed topology is simple, inexpensive and easy to manufacture.
Originality/value
Electromagnetic performance comparison with different topologies proposed earlier in literature is carried out to prove the performance superiority of the proposed design.
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