The application of linear induction motors to conveyors

Laithwaite, E.R.; Tipping, D.; Hesmondhalgh, D.E.

doi:10.1049/pi-a.1960.0061

Cited by 20 publications

(4 citation statements)

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“…A lower input power at a given speed is possible if the supply frequency is reduced and the pole pitch increased to compensate. 4 A further set of curves for the same motor, supplied at lower frequencies, is plotted in Fig. 10 and shows marked improvements in the power consumption at the lower speeds.…”

Section: A Detailed Design Studymentioning

confidence: 97%

Linear induction motors for low-speed and standstill application

Nix

Laithwaite

1966

Proc. Inst. Electr. Eng. UK

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SynopsisDevices which are required to produce force with virtually no movement have zero power output. The effectiveness of such devices cannot therefore be assessed in terms of their efficiency or. power/weight ratio. Quantities which are important in the design of force-producing machines or 'actuators' are the force/input, force/weight and force/cost ratios and similar quantities. Reliability is also often a potent factor. The paper examines the use of linear motors as actuators under these criteria and formulates design procedure. The optimisation of the force/input ratio for a machine whose speed is not zero, but low in comparison to that of conventional machines, is carried out with the aid of a computer program. Considerable simplification of manufacture is achieved by the use of the tubular or axial-flux form of construction. Forces in linear motors of both transverse and axial-flux types are calculated, taking end effects into account. The design of an existing commercially produced tubular actuator is discussed. List of principal symbolsa = rotor length B c = peak core flux density* B g = peak airgap flux density* B t -peak rotor leakage flux density* / = supply frequency F = force g = effective airgap G = goodness factor J m = peak stator-magnetising-current loading* J r = peak rotor current loading* J s = peak stator current loading* l r = rotor leakage inductance per square p = pole pitch P r = rotor power input s = stator length v s -synchronous velocity Z = rotor-core radius /x 0 -permeability of free space p r = rotor surface resistivity p s = stator surface resistivity a = slip T, = rotor leakage time constant co = angular supply frequency * Lower-case letters indicate instantaneous values IntroductionIn an earlier paper 1 it was shown that induction machines of high efficiency can only be designed when the surface speed of the rotor is high. Every electrical machine consists of a magnetic circuit linked with one or more electric circuits, and the relationship between the conductivity of copper and the permeability of free space determines the law relating surface speed and goodness of machine. Applications for linear motors therefore appear to be severely limited by the fact that there is no convenient linear equivalent of the gear, for many of the linear motions required by. industry are limited to speeds below lOft/s. There has been, however, a growing awareness among engineers, particularly in the last two decades, that efficiency and power factor are not the only criteria by which a machine can be judged, and that power/weight ratio and cost are often of greater significance

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Section: A Detailed Design Studymentioning

confidence: 97%

Linear induction motors for low-speed and standstill application

Nix

Laithwaite

1966

Proc. Inst. Electr. Eng. UK

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“…On the other hand, if a motor with high applied frequency is to be used at low speed, the output power and efficiency would be low, and then, the performance of a low-speed machine cannot be evaluated in terms of output power or efficiency. However, an improvement in performance, and thus, efficiency may be achieved when a low-speed motor is fed from a low-frequency [22]. Preliminary design parameters and dimensions of the LIM with toroidal winding are given in Table I.…”

Section: Design Of a Low-speed Lim With Toroidal Windingmentioning

confidence: 99%

Design Optimization, Prototyping, and Performance Evaluation of a Low-Speed Linear Induction Motor With Toroidal Winding

Pourmoosa

Mirsalim

2015

IEEE Trans. Energy Convers.

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In this paper, a study of the performance and experimental results for a low-speed linear induction motor (LIM) with toroidal winding is presented. The main idea behind the proposed winding is to provide better performance and efficiency in space-constrained applications where a LIM with much higher primary length in comparison with the primary width is required. The LIM with toroidal winding in this case enjoys the advantage of short end-connection length, which can provide more superior performance than a distributed winding linear induction motor (DWLIM). Also, as the motor is designed to operate at low speed, the output power, and thus efficiency, would be low, and then the performance of such machines cannot be evaluated in terms of output power or efficiency. However, an improvement in performance, and thus efficiency, may be achieved when the low-speed motor is fed from a low-frequency supply. This paper mainly focuses on the design optimization, prototyping, and performance evaluation of a low-speed LIM with toroidal winding, and also provides a detailed comparison between the LIM with toroidal winding and a DWLIM.

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“…So far as the author is aware, research into DLIMs with squirrel-cage secondaries without ferromagnetic cores has not had a high priority. If the air-core squirrel-cage secondary is elastic, it would be useful in, for example, conveyor systems [2][3][4]. The squirrel-cage secondary is more resistant and tougher than those consisting of a homogeneous belt made of copper.…”

Section: List Of Principal Symbolsmentioning

confidence: 99%

Simplified theory of double-sided linear induction motor with squirrel-cage elastic secondary

Gieras

1983

IEE Proc. B Electr. Power Appl. UK

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The theoretical analysis, the method of calculation and the experimental tests on a double-sided linear induction motor (DLIM) with squirrel-cage secondary member are given. The air-core secondary is elastic and consists of copper bars, a braided conductive lines as end rings and woven plastics filaments. Equations of two-dimensional and one-dimensional magnetic-flux-density distribution in the secondary and the airgap are derived. Formulas for resistance and reactance of the squirrel-cage secondary and the thrust of DLIM are obtained. The end effect caused by the open-endedness of the airgap is taken into account. Performance characteristics, i.e. no-load and short-circuit curves obtained from calculations and measurements, are compared. Streszczenie: Podano analiz? teoretycznq, metod? obliczeri i badania eksperymentalne dwustronnego silnika indukcyjnogo liniowego (DSIL) o klatkowej cz^sci wtornej. Bezrdzeniowa cz?sc wtorna jest elastyczna i skjada si? z pr?tow miedzianych pofeczonych ze soba. na koncach linka. miedziana. i przeplecionych tasmq z tworzywa sztucznego. Wyznaczono rownania dwuwymiarowego i jednowymiarowego rozkfadu indukcji magnetycznej w czesci wtornej i szczelinie powietrznej. Na podstawie tych rownan wyprowadzono zaleznosci na rezystancj? i reaktancje klatkowej cze_sci wtornej oraz na si/e cia.gu DSIL. Uwzgl?dniono zjawiska kohcowe wywofane skonczona, d/ugoscia. rdzenia cz?sci pierwotnej. Obliczone charakterystyki biegu ja/owego, obci^zenia oraz zwarcia porownano z charakterystykami zmierzonymi. '

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The application of linear induction motors to conveyors

Cited by 20 publications

References 4 publications

Linear induction motors for low-speed and standstill application

Linear induction motors for low-speed and standstill application

Design Optimization, Prototyping, and Performance Evaluation of a Low-Speed Linear Induction Motor With Toroidal Winding

Simplified theory of double-sided linear induction motor with squirrel-cage elastic secondary

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