Analysis of a short-stroke, single-phase, quasi-Halbach magnetised tubular permanent magnet motor for linear compressor applications
TL;DR: In this paper, a single-phase, short-stroke, reciprocating tubular motor with a quasi-Halbach magnetized moving-magnet armature is described and the magnetic field distribution, the back-emf and the thrust force of the motor are established analytically in the cylindrical co-ordinate system, and predictions are compared with results derived from finite-element (FE) analysis.
Abstract: The analysis of a novel single-phase, short-stroke, reciprocating tubular motor with a quasi-Halbach magnetised moving-magnet armature is described. The motor was developed for applications such as linear compressors. The magnetic field distribution, the back-emf and the thrust force of the motor are established analytically in the cylindrical co-ordinate system, and predictions are compared with results derived from finite-element (FE) analysis. It is shown that the difference between the analytical and FE predicted average emf (thrust force) over the operating stroke of 0.01 m is <5%. The analysis and the emf and thrust force predictions are validated by measurements.
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TL;DR: It is shown that the motor efficiency can be optimized with respect to two leading dimensional ratios, and an analytical formula for predicting iron loss is presented.
Abstract: This paper describes a design methodology to achieve optimal performance for a short-stroke single-phase tubular permanent-magnet motor which drives a reciprocating vapor compressor. The steady-state characteristic of the direct-drive linear-motor compressor system is analyzed, an analytical formula for predicting iron loss is presented, and a motor-design procedure which takes into account the effect of compressor loads under nominal operating condition is formulated. It is shown that the motor efficiency can be optimized with respect to two leading dimensional ratios. Experimental results validate the proposed design methodology.
126Â citations
Cites background from "Analysis of a short-stroke, single-..."
...1, for linear compressor applications has been reported and its performance analyzed [7]....
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TL;DR: In this paper, an analytical model for double-sided permanent-magnet radial-flux eddy-current couplers is presented that can easily handle complex geometries.
Abstract: Analytical models are widely utilised in the study and performance prediction of electric machines by providing fast, yet accurate solutions. By combining conventional magnetic equivalent circuit techniques with Faraday's and Ampere's laws, an analytical model for double-sided permanent-magnet radial-flux eddy-current couplers is presented that can easily handle complex geometries. The proposed approach is also capable of taking the three-dimensional (3D) impacts into account. The characteristics and design considerations are also studied for a surface-mounted permanent-magnet structure. Moreover, the 2D and 3D finite-element methods are employed to verify the results, as well as transient study of the device under two different scenarios. Finally, sensitivity analysis is carried out to investigate the influence of the design variables on the characteristics of the coupler, which provides valuable information in the current and future studies of such devices.
62Â citations
TL;DR: In this article, a general analytical model was developed to predict the electromagnetic performance of slotted/slotless permanent magnet (PM) brushless machines with both even and odd-segment Halbach array, having different magnet remanence, magnetisation angle and arc for each single magnet segment.
Abstract: Since a Halbach array exhibits a number of attractive features, it has been increasingly applied to different market sectors, including aerospace, industrial, domestic, renewable and healthcare and so on. The need of fast global optimisation, cost-effective design and physical understanding of the relationship between parameters and performance requires a powerful analytical model. Hence, this study develops a general analytical model which is capable of predicting the electromagnetic performance of slotted/slotless permanent magnet (PM) brushless machines with both even- and odd-segment Halbach array, having different magnet remanence, magnetisation angle and arc for each single magnet segment. The emphasis has been on the magnetisation which is the key in analytical modelling of PM machines having a segmented Halbach array and its investigation. The validity of proposed analytical model is extensively examined by finite-element analyses, together with its applications for global optimisation and comparative study.
49Â citations
TL;DR: A learning feed-forward current controller for the linear compressors is proposed that comprises a conventional feedback proportional-integral controller and aFeed-forward B-spline neural network is trained online and in real time in order to minimize the current tracking error.
Abstract: Direct-drive linear reciprocating compressors offer numerous advantages over conventional counterparts which are usually driven by a rotary induction motor via a crank shaft. However, to ensure efficient and reliable operation under all conditions, it is essential that motor current of a linear compressor follows a sinusoidal current command with a frequency which matches the system resonant frequency. The design of a high-performance current controller for linear compressor drive presents a challenge since the system is highly nonlinear, and an effective solution must be low cost. In this paper, a learning feed-forward current controller for the linear compressors is proposed. It comprises a conventional feedback proportional-integral controller and a feed-forward B-spline neural network (BSNN). The feed-forward BSNN is trained online and in real time in order to minimize the current tracking error. Extensive simulation and experiment results with a prototype linear compressor show that the proposed current controller exhibits high steady state and transient performance.
48Â citations
Cites background from "Analysis of a short-stroke, single-..."
...motor [4] with 94% efficiency when operating at the system resonant frequency [5]....
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TL;DR: In this article, an analytical prediction and measurement technique for quantifying iron loss in a short-stroke, single-phase, tubular permanent-magnet machine which is developed for direct-drive linear compressors in domestic refrigeration applications is described.
Abstract: This paper describes analytical prediction and measurement techniques for quantifying iron loss in a short-stroke, single-phase, tubular permanent-magnet machine which is developed for direct-drive linear compressors in domestic refrigeration applications. The technique is based on the analytically derived magnetic field distributions in three discrete regions of the stator core and a well established iron loss model, and is validated by finite element analysis. An iron loss measurement technique is developed in which the moving magnet armature is supported by flexural springs that eliminate frictional loss and facilitate resonant operation during measurement. A good agreement between the prediction and measurement is observed.
48Â citations
Cites background or methods from "Analysis of a short-stroke, single-..."
...where is determined analytically using the formula described in [5] and is the tooth tip width....
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...1, has been developed for linear compressor applications [4], [5]....
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...The analytical method for iron loss calculation in the shortstroke single-phase tubular permanent magnet motor employs analytical expressions reported in [5] for predicting the magnetic field distribution in the air gap due to the quasi-Halbach magnetization and armature reaction, and, thereby, to deduce flux density waveforms in three discrete regions of the stator core, viz....
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References
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TL;DR: A general framework for the analysis and design of a class of tubular linear permanent magnet machines is described, established analytically in terms of a magnetic vector potential and cylindrical coordinate formulation, and the results are validated extensively by comparison with finite element analyses.
Abstract: A general framework for the analysis and design of a class of tubular linear permanent magnet machines is described. The open-circuit and armature reaction magnetic field distributions are established analytically in terms of a magnetic vector potential and cylindrical coordinate formulation, and the results are validated extensively by comparison with finite element analyses. The analytical field solutions allow the prediction of the thrust force, the winding emf, and the self- and mutual-winding inductances in closed forms. These facilitate the characterization of tubular machine topologies and provide a basis for comparative studies, design optimization, and machine dynamic modeling. Some practical issues, such as the effects of slotting and fringing, have also been accounted for and validated by measurements.
388Â citations
10 Dec 2002
TL;DR: In this paper, the performance of a tubular linear permanent magnet (TL-PM) motor is highlighted, including specific force, maximum acceleration, and cost, and a comparison between predicted and measured performance on a motor prototype is reported.
Abstract: This paper deals with tubular linear permanent-magnet (TL-PM) motors, including different topologies, i.e., interior and surface-mounted PMs, slotted and slotless motors. After some preliminary analytical considerations, the performance of the TL-PM motor is highlighted, including specific force, maximum acceleration, and cost. Not only are the advantages emphasized, but also the drawbacks, such as detent forces and attractive radial forces due to eccentricity. Different models have been adopted in the various analyses, including two-dimensional and three-dimensional finite-element analysis as needed. In addition, a comparison between predicted and measured performance on a motor prototype are reported.
204Â citations
TL;DR: In this article, the authors describe the analysis, design, and experimental characterization of three-phase tubular modular permanent-magnet machines equipped with quasi-Halbach magnetized magnets and establish an analytical expression for the open-circuit magnetic field distribution, formulated in the cylindrical coordinate system.
Abstract: This paper describes the analysis, design, and experimental characterization of three-phase tubular modular permanent-magnet machines equipped with quasi-Halbach magnetized magnets. It identifies feasible slot/pole number combinations and discusses their relative merits. It establishes an analytical expression for the open-circuit magnetic field distribution, formulated in the cylindrical coordinate system. The expression has been verified by finite-element analysis. The analytical solution allows the prediction of the thrust force and electromotive force in closed forms, and provides an effective tool for design optimization, as will be described in Part II of the paper.
163Â citations
TL;DR: In this article, the influence of leading design parameters on the performance of a radially magnetized, iron-cored, tubular permanent-magnet machine and its drive system was deduced from analytical field solutions.
Abstract: In this paper we deduce, from analytical field solutions, the influence of leading design parameters on the performance of a radially magnetized, iron-cored, tubular permanent-magnet machine and its drive system. We derive analytical formulas for predicting the open-circuit electromotive force, the thrust force, the iron loss, and the winding resistance and inductances, as well as the converter losses. The force density, the machine and drive system efficiencies, and the power factor and converter volt-ampere (VA) rating are established as functions of a set of machine dimensional ratios, with due account of magnetic saturation and subject to a specified thermal constraint. We validate the utility and accuracy of the analytically derived formulas by finite-element calculations. Finally, we show that the design optimization of such a linear drive system must account for the losses and VA rating of the converter as well as the design parameters of the tubular machine.
136Â citations
01 Sep 2001
TL;DR: In this paper, the influence of the leading design parameters on the performance of slotless tubular permanent magnet machines, and the relative merits of different tubular linear machine topologies, are deduced from analytical field solutions.
Abstract: The influence of the leading design parameters on the performance of slotless tubular permanent magnet machines, and the relative merits of different tubular linear machine topologies, are deduced from analytical field solutions. The force capability and force ripple are established as functions of a set of dimensional ratios, with due account of magnetic saturation and subject to a specific thermal constraint. The results provide an effective means of making comparative studies and optimising machine designs, and will aid the design process when addressing a given performance specification.
135Â citations