• Title/Summary/Keyword: Electro magnetic force

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Analysis of Squirrel Cage Induction Motors with Rotor Eccentricity (농형 유도전동기의 회전자 편심에 따른 특성분석)

  • Kim, Mi-Jung;Kim, Byong-Kuk;Moon, Ji-Woo;Cho, Yun-Hyun;Hwang, Don-Ha;Kang, Dong-Sik
    • Proceedings of the KIEE Conference
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    • 2006.07b
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    • pp.825-826
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    • 2006
  • This paper describes the effects of air gap eccentricity in induction machines. Asymmetric electro-magnetic force caused by the frictional worn bearing, rotor misalignment and unbalanced rotor etc. generates an asymmetrical operation, vibration and electro-magnetic noise. In this paper, we focus on investigating the asymmetrical operation considering of unbalanced magnetic force in squirrel-cage induction motor with 380 [V], 7.5 [kW], 4P, 1,768 [rpm]. The effects of the rotor eccentricity, magnetic force are investigated by finite element method (FEM) and experiment. The results can be useful for on-line monitoring of an induction motor.

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Study of micro-plastics separation from sea water with electro-magnetic force

  • Nomura, Naoki;Mishima, Fumihito;Nishijima, Shigehiro
    • Progress in Superconductivity and Cryogenics
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    • v.23 no.3
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    • pp.10-13
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    • 2021
  • The method of removing micro-plastics from sea water has been developed using electro-magnetic force. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. The Lorentz force was generated in simulated sea water and its reaction force was applied to the micro-plastic to control their motion. Lorentz force was generated downward and the reaction force to the plastics was upward. The plastic used in the experiment was polystyrene with a diameter of 6 mm, and the density was 1.07 g/cm3. The polystyrene sphere levitated at the current density of 0.83 A/cm2 and the external field of 0.87T. The particle trajectory calculation was also made to design separation system using superconducting magnet.

Design of Hybrid Mount to Naval Shipboard Considering Shock Resistance (내충격 성능을 고려한 함정용 하이브리드 마운트의 설계)

  • Jo, Hye-Young;Shin, Yun-Ho;Moon, Seok-Jun;Jung, Woo-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2012.10a
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    • pp.102-107
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    • 2012
  • In this study, the design procedure of hybrid active mount by an electro-magnetic actuator is proposed to reduce the transmitted force from naval shipboard equipment to ship hull structure. The hybrid type mount which is composed of a passive rubber element and an electro-magnetic actuator is introduced and, through the vibration measurement for the objective pump system, the required force of the actuator is computed and discussed in detail. The initial designs were supposed for three types, one is moving coil type actuator and the others are moving permanent magnet type actuators. Based on the initial design concept, the final designs considering shock resistance and interference with mover and stator are proposed and examined.

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Double Electro-Magnetic Force Compensation Method for the Micro Force Measurement (미소 힘 측정을 위한 이중 전자기힘 보상방법)

  • 최임묵;우삼용;김부식;김수현
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.2
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    • pp.104-111
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    • 2003
  • Micro force measurement is required more frequently for a precision manufacturing and investment in fields of precision industries such as semiconductor, chemistry and biology, and so forth. Null balance method has been introduced as an alternative of a loadcell. Loadcells have advantages in aspects of low cost and easy manufacturing, but have also the limitation in resolution and sensitivity to environment variations. In this paper, null balance method is explained and the dominant parameters related to system performances are mentioned. Null position sensor, electromagnetic system and controller are investigated. Also, the characteristic experiment is carried out in order to estimate the resolution and the measurement range. In order to overcome the limitation by the drift of position sensor and the performance of controller, double electromagnetic force compensation method is proposed and experimented. After controlling and filtering, the resolution under $\pm$ 1mg and measurement range over 300g could be obtained.

Study of a Hybrid Magnet Array for an Electrodynamic Maglev Control

  • Ham, Chan;Ko, Wonsuk;Lin, Kuo-Chi;Joo, Younghoon
    • Journal of Magnetics
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    • v.18 no.3
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    • pp.370-374
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    • 2013
  • This paper introduces an innovative hybrid array consisting of both permanent and electro magnets. It will enable us to develop an active control mechanism for underdamped electro-dynamic suspension (EDS) Maglev systems. The proposed scheme is based on the Halbach array configuration which takes the major technical advantage from the original Halbach characteristics: a strongly concentrated magnetic field on one side of the array and a cancelled field on the opposite side. In addition, the unique feature of the proposed concept only differs from the Halbach array with permanent magnets. The total magnetic field of the array can be actively controlled through the current of the electro-magnet's coils. As a result, the magnetic force produced by the proposed hybrid array can also be controlled actively. This study focuses on the magnetic characteristics and capability of the proposed array as compared to the basic Halbach concept. The results show that the proposed array is capable of producing not only an equivalent suspension force of the basic Halbach permanent magnet array but also a controlled mode. Consequently, the effectiveness of the proposed array confirms that this study can be used as a technical framework to develop an active control mechanism for an EDS Maglev system.

The Elementary Study on the Development of a Sensor for Measurement of Steel Corrosion by Transient Electro-Magnetic (TEM) Method (TEM 법에 의한 철근 부식 측정 센서 개발에 대한 기초 연구)

  • 이상호;한정섭
    • Journal of Ocean Engineering and Technology
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    • v.15 no.1
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    • pp.57-66
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    • 2001
  • In order to measure steel corrosion in mortar by a transient electro-magnetic (TEM) Method, the development of the sensors have been studied. The sensors were made of enamelled wire with diameter of 0.25mm and Acril. The sensor configuration was used as a coincident loop type. The secondary electro motive force(EMF) was measured with SIROTEM III. The accelerator was equipped with the SIROTEM III. The accelerator permits the transmitter to turn off approximately 10~15 times faster than normal. The high resolution time series used for very shallow or high resistivity investigation was selected. The steels were embedded in mortar which were made from sand : cement : water ratio of 2 : 1: 0.5. The mortar specimen was 50cm long, 20cm wide and 10cm thick. To investigate steel corrosion in mortar, the sensors used were with 2$\times$2$cm^2$(3, 6, 9$\Omega$), 3$\times$3$cm^2$(3, 6, 9$\Omega$) and 6$\times$6$cm^2$(3, 6, 9$\Omega$). The obtained result obtained showed that the sensor 8(6$\times$6$cm^2$, 6$\Omega$) was the proper sensor for the measurement of steel corrosion in mortar.

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Characteristics Analysis on the Effects of Rotor Eccentricity in Squirrel-cage Induction Motor (회전자 편심을 고려한 농형 유도전동기의 특성해석)

  • Kim, Mi-Jung;Kim, Byong-Kuk;Hwang, Don-Ha;Kang, Dong-Sik;Cho, Yun-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.2
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    • pp.289-294
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    • 2007
  • This paper describes the effects of rotor eccentricity in squirrel cage induction machines. Asymmetric electro-magnetic force caused by the frictional worn bearing, rotor misalignment and unbalanced rotor etc. generates an asymmetrical operation, vibration and electro-magnetic noise. The need for detection of these rotor eccentricities has pushed the development of monitoring methods with increasing sensitivity and noise immunity. In this paper, we focus on investigating the asymmetrical operation considering of unbalanced magnetic pull in squirrel-cage induction motor with 380 [V], 7.5 [kW], 4P, 1,768 [rpm]. The effects of the non-symmetric rotor and magnetic force are simulated by finite element method (FEM) and tested using search coils for measuring the actual air-gap flux.

A Study on Shape Optimization of Electro-Magnetic Proportional Solenoid (비례솔레노이드 형상 최적설계에 관한 연구)

  • Yun S.N.;Ham Y.B.;Kang J.H.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.2 no.3
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    • pp.1-5
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    • 2005
  • There are two types of solenoid actuator for force and position control of the fluid power system. One is an on-off solenoid actuator and the other is an electro-magnetic proportional actuator. They have some different characteristics for attraction force according to solenoid shape. Attraction force of the on-off solenoid actuator only depends on flux density. And the stroke-force characteristics of the proportional solenoid actuator are determined by the shape of the control cone. In this paper, steady state characteristics of the solenoid actuator for electro-hydraulic proportional valve determined by the shape of control cone are analyzed using finite element method and it is confirmed that the proportional solenoid actuator has a constant attractive force in the control region independently on the stroke position. And the shape of control cone is optimized using 1+1 evolution strategy to get a constant force. In the optimization algorithm, control cone length, thickness and taper length are used as a design parameter.

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A Study on the Measurement of Steel Corrosion in Mortar by TEM Method (TEM법에 의한 모르타르 중의 철근 부식 측정에 관한 연구)

  • Lee Sang-Ho;Han Jeong-Seb
    • Journal of Ocean Engineering and Technology
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    • v.20 no.2 s.69
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    • pp.59-65
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    • 2006
  • Steel, as a reinforcing mechanism in concrete, provides the tensile strength that is lacking in concrete, alone, and the high alkaline environment (pH 12.5) in concrete offers satisfactory protection against most corrosion of the steel. However, the corrosion of reinforcing steel in concrete can occur by chloride attack or carbonation, and it can cause a loss of integrity a section and concrete failure through cracking and spalling. In this study, a transient electro magnetic method (TEM) of a nondestructive technique is adapted to study the measuring method of steel corrosion in mortar. The sensor was made of an enameled wire, with a diameter of 0.25mm and anacril. He sensor configuration used was a coincident loop type. The secondary electro motive force (2nd EMF) was measured with SIROTEMIII, which equipped the accelerator. The accelerator allowsthe transmitter to turn off approximately $10\sim15$ times faster than normal. The high-resolution time series, used for very shallow or a high resistivity investigation was selected. After steels were corroded by the salt spray, during 4, 8, 15 and 25 days, they were embedded in mortar. The content results acquired in this study are as follows. The variation of the secondary electro motive force (2nd EMF) was shown by the change of steel surface with different corrosion time steel. It was confirmed that measurement of steel corrosion in mortar by a transient electro-magnetic method (TEM) can be possible.

Test Study about Electro magnetic force effect to apply dredging soil transport (준설토 이송시 유동효율에 미치는 전자기장 인가 영향에 대한 실험적 고찰)

  • Kim, Yuseung;Lee, Myunghan;Lee, Yunjin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.4
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    • pp.2883-2890
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    • 2015
  • As the research about increasing the efficiency of dredging soil transport, the technology, which reduce the friction between pipe wall and fluid in the pipe and disturbed generating pipe blockage, has been developed. So for the purpose of applying this technology to real construction site, main test has been tried at the real scale test in field(500m dredging soil transport length). As a test result, this paper will show 30% flow efficiency increasing by permitted electro magnetic force to the pipe. And test result was evaluated as a ultra sonic velocity profiler.