Power-factor improvement in linear induction motors

Laithwaite, E.R.; Kuznetsov, S.B.

doi:10.1049/ip-b.1981.0030

Cited by 3 publications

(2 citation statements)

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“…Slip was measured optically and was maintained at a high value for the purpose of operating the machine close to the maximum thrust pull-out slip of which is calculated approximately [5] where n = number of stator total poles (6) for both entry and exit poles. The maximum differences in phase currents for the combined upper or lower stator units is 7% during peak acceleration mode.…”

Section: Test Resultsmentioning

confidence: 99%

“…The ASC concept raised the overall efficiency from 62% to 74% by a comprehensive system of design improvements centered on shifting the location of peak flux from the block end to two-thirds along the stator block. [5] The ASC LIMs can attain an intermittent power density of 22 kW/kg and steady-state power density of 7 kW/kg with a liquid conduction-cooled stator.…”

Section: New Techniquesmentioning

confidence: 99%

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High Velocity Linear Induction Launcher with Exit-Edge Compensation for Testing of Aerospace Components

Kuznetsov¹,

Marriott

2008

2008 14th Symposium on Electromagnetic Launch Technology

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Advances in ultra high speed linear induction electromagnetic launchers over the past decade have focused on magnetic compensation of the exit and entry-edge transient flux wave to produce efficient and compact linear electric machinery. The paper discusses two approaches to edge compensation in long-stator induction catapults with typical end speeds of 150 to 1,500 m/s. In classical linear induction machines, the exit-edge effect is manifest as two auxiliary traveling waves that produce a magnetic drag on the projectile and a loss of magnetic flux over the main surface of the machine. In the new design for the Stator Compensated Induction Machine (SCIM) high velocity launcher, the exit-edge effect is nulled by a dual wavelength machine or alternately the airgap flux is peaked at a location prior to the exit edge.A four (4) stage LIM catapult is presently being constructed for 180 m/s end speed operation using double-sided longitudinal flux machines. Advanced exit and entry edge compensation is being used to maximize system efficiency, and minimize stray heating of the reaction armature. Each stage will output approximately 60 kN of force and produce over 500 G's of acceleration on the armature. The advantage of this design is there is no ablation to the projectile and no sliding contacts, allowing repeated firing of the launcher without maintenance of any sort.The paper shows results of a parametric study for 500 m/s and 1,500 m/s linear induction launchers incorporating two of the latest compensation techniques for an air-core stator primary and an iron-core primary winding. Typical thrust densities for these machines are in the range of 150 kN/sq.m. to 225 kN/sq.m. and these compete favorably with permanent magnet linear synchronous machines. The operational advantages of the high speed SCIM launcher are shown by eliminating the need for pole-angle position sensors as would be required by synchronous systems. The stator power factor is also improved.

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Section: Test Resultsmentioning

confidence: 99%

Section: New Techniquesmentioning

confidence: 99%