• Title, Summary, Keyword: Coil turn

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Shorted Turn in the Flat Coil Actuator for Fast Initial Response

  • Hwang, Ki-Il;Seo, Tae-Won;Song, Bong-Sob;Kim, Jin-Ho
    • Journal of Magnetics
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    • v.17 no.1
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    • pp.56-60
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    • 2012
  • This paper presents an analysis and experiment of the flat coil actuator with shorted turn. The flat coil actuator is widely used in high precision products because it has no friction between the moving coil and the guide. A shorted turn and a center pole are placed into the flat coil actuator in order to reduce the inductance of the coil and improve the initial response when the actuator is voltage-driven. Enhanced dynamic performance of the flat coil actuator with shorted turn was demonstrated by simulation and experiment.

Shorted Turn in the Hybrid Magnet Engine Valve Actuator for Enhanced Dynamic Performance

  • Yi, Hwa Cho;Hwang, Ki Il;Kim, Jihun;Kim, Jin Ho
    • Journal of Magnetics
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    • v.18 no.4
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    • pp.466-472
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    • 2013
  • This paper presents a new design of the hybrid magnet engine valve actuator using the shorted turn for enhanced dynamic performance. The quick response of coil electric current is the most important factor that determines the opening and closing performance of the hybrid magnet engine valve. The conventional hybrid magnet engine valve actuator, however, has a delayed initial electric current rising when it is driven by voltage control because of the coil inductance which is a typical characteristic of an electromagnetic coil. A shorted turn is newly placed into the upper yoke of the hybrid magnet engine valve actuator to reduce coil inductance and thus, to hasten the initial electric current rising. We performed a dynamic finite element analysis to demonstrate the improvement of the dynamic characteristics of the hybrid magnet engine valve actuator due to the shorted turn.

Effect of a Coil Shape on an Impulse Velocity of the Electromagnetic Welding (전자기 용접의 충돌 속도에 대한 코일 형상의 영향)

  • Park, H.;Lee, K.;Lee, J.;Lee, Y.;Kim, D.
    • Transactions of Materials Processing
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    • v.28 no.3
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    • pp.135-144
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    • 2019
  • Electromagnetic impulse welding (EMIW) is a type of solid state welding using the Lorentz force generated by interaction between the magnetic field of the coil and the current induced in the workpiece. Although many experimental studies have been investigated on the expansion and compression welding of tube using the EMIW process, studies on the EMIW process of lap joint between flat sheets are uncommon. Since the magnetic field enveloped inside the tube can be controlled with ease, the electromagnetic technique has been widely used for tube welding. Conversely, it is difficult to control the magnetic field in the flat sheet welding so as to obtain the required welding velocity. The current study analyzed the effects of coil shape on the impulse velocity for suitable flat one-turn coil for the EMIW of the flat sheets. The finite element (FE) multi-physics simulation involving magnetic and structural field of EMIW were conducted with the commercial software LS-DYNA to evaluate the several shape variables, viz., influence of various widths, thicknesses, gaps and standoff distances of the flat one-turn coil on the impulse velocity. To obtain maximum impulse velocity, the flat one-turn coil was designed based on the FE simulation results. The experiments were performed using an aluminum alloy 1050 sheets of 1.0mm thickness using the designed flat one-turn coil. Through the microscopic interfacial analysis of the welded specimens, the interfacial connectivity was observed to have no defects. In addition, the single lap joint tests were performed to evaluate the welding strength, and a fracture occurred in the base material. As a result, a flat one-turn coil was successfully designed to guarantee welding with bond strength equal to or greater than the base material strength.

A Study on Thermal Stability of the Non-insulated HTS Racetrack-type Coil Under Various External Pressures Applied to Straight Sections (무절연 고온 초전도 레이스트랙형 코일의 직선구간 압력변화에 따른 열적 안정성 연구)

  • Kwon, O.J.;Kim, K.L.;Choi, Y.H.;Yang, D.G.;Kim, Y.G.;Lee, T.S.;Ko, T.K.;Lee, H.G.
    • Progress in Superconductivity and Cryogenics
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    • v.14 no.3
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    • pp.33-37
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    • 2012
  • An HTS racetrack-type coil without turn-to-turn insulation was characterized by critical current, sudden discharge, and over-current tests with respect to external pressures applied to the straight sections of the coil. The thermal stability of the non-insulated HTS racetrack-type coil was remarkably enhanced with increasing external pressure applied to the straight sections of racetrack-type coil. Furthermore, over-current test results confirmed that the non-insulated HTS racetrack-type coil with increased turn-to-turn thermal contact has the potential to be manufactured into field coils of HTS wind turbine generators with highly enhanced thermal and electrical stabilities.

Insulation Design and Testing of HTS coil for 6.6 kV Class HTSFCL (6.6kV급 고온초전도 한류기용 HTS 코일의 절연 설계 및 시험)

  • 백승명;정종만;곽동순;류엔반둥;김상현
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • pp.263-268
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    • 2003
  • The Electrical insulation design and testing of high temperature superconducting (HTS) coil for high temperature superconducting fault current limiter (HTSFCL) has been performed. Electrical insulating factors of HTS coil for HTSFCL are turn-to-turn, layer-to-layer. The electrical insulation of turn-to-turn depends on surface length, and the electrical insulation of layer-to-layer depends on surface length and breakdown strength of L$N_2$. Therefore, two basic characteristics of breakdown and flashover voltage were experimentally investigated to design electrical insulation for 6.6㎸ Class HTSFCL. We used Weibull distribution to set electric field strength for insulation design. And mini-model HTS coil for HTSFCL was designed by using Weibull distribution and was manufactured to investigate breakdown characteristics. The mini-model HTS coil had passed in AC and Impulse withstand test.

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Field analysis of end_turn coil of HV induction motor (고압 회전기에서 코일 단부의 전계 해석)

  • Park, Seung-Bae;Kim, Do-Wan;Jung, Hyun-Kyo
    • Proceedings of the KIEE Conference
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    • pp.70-72
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    • 1998
  • Because of using PWM inverters and converters. The problems of insulation breakdown is emerging in both high voltage motors and general motors. In conventional methods, the viewpoint of surge problems is wave propagation with or without cable and inverter. For the purpose of knowing the situation of insulation breakdown, the end-turn coil of windings in the motor winding insulation structure is modelled by FEM, and field analysis of that is done. For first step, only end-turn coil is modelled and the model is simulated with FEM by approximating the resistivity of metallic foil surrounding insulation layers with having nonlinear property. Next, the result of simulation with nonlinear resistivity are compared with the result of linear resistivity. Because of microscope analysis, there is the problem of generalization but the situation of corona discharge in end-turn coil will be explained from this simulation.

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Study of Shorted-turn for Cylindrical Synchronous Generator Rotor (원통형 동기발전기 회전자의 층간단락에 관한 연구)

  • Kim, Young-Jun;Kim, Jang-Mok;Lee, Sang-Hyuk;Ahn, Jin-Woo
    • Journal of the Korean Society of Safety
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    • v.21 no.2
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    • pp.52-56
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    • 2006
  • This paper describes the methods for the detection of shorted-turn in the rotor of a cylindrical synchronous generator. A search coil is installed in the air-gap to detect the shorted-turn. The occurrence of a fault in the rotor winding results in a decrease of the induced voltages in the stator. And the magnitude of the rotor flux can be estimated by using the search coil and the estimated stator voltages respectively. And the magnitude of the estimated rotor flux is used for discriminating the rotor windings short or not by detecting the magnitude of the rotor flux. The method using a search coil located in the air-gap can detect not only the occurrence of a turn fault but also its position in the rotor winding. But the method using the estimated stator voltages gives the magnitude of the rotor flux, and only the number of a short-turn.

Double-excitation Type Single Sheet Tester (2방향 자계인가형 싱글 시트 테스터)

  • Kim, Hong-Jung;Koh, Chang-Seop;Hong, Sun-Gi;Sin, Pan-Suk;Fujiwara, Koji
    • Proceedings of the KIEE Conference
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    • pp.73-75
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    • 2005
  • 이 논문에서는 전기강판의 자계 특성을 측정하기 위하여 이방향 자계인가형 싱글 시트 테스터가 개발되어졌다. 이 개발된 시스템은 자속밀도와 자계세기를 B-coil과 H-coil로 측정할 수 있다. B-coil은 rolling direction과 transverse direction에 대하여 각각 1-turn 감겨져 있으며 H-coil은 200-turn 각각 감겨져있다. 실험을 통하여 이 시스템은 방향성 전기 강판의 경우 rolling direction에 대하여 1.8 [T]까지 측정되어질 수 있다.

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Contact resistance characteristics of 2G HTS coils with metal insulation

  • Sohn, M.H.;Ha, H.;Kim, S.K.
    • Progress in Superconductivity and Cryogenics
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    • v.20 no.4
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    • pp.26-30
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    • 2018
  • The turn-to-turn contact resistance of 2G high temperature superconducting (HTS) coils with metal insulation (MI) is closely related to the stability of the coils, current charging rate and delay time [1]. MI coils were fabricated using five kinds of metal tapes such as aluminum (Al) tape, brass tape, stainless steel (SS) tape, copper (Cu)-plated tape and one-sided Cu-plated SS tape. The turn-to-turn contact surface resistances of co-winding model coils using Al tape, brass tape, and SS tape were 342.6, 343.6 and $724.8{\mu}{\Omega}{\cdot}cm^2$, respectively. The turn-to-turn contact resistance of the model coil using the one-sided Cu-plated SS tape was $ 248.8{\mu}{\Omega}{\cdot}cm^2$, which was lower than that of Al and brass tape. Al or brass tape can be used to reduce contact resistance and improve the stability of the coil. Considering strength, SS tape is recommended. For strength and low contact resistance, SS tape with copper plating on one side can be used.