• Title/Summary/Keyword: major hysteresis loop

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Major B-H Loop Measurement of Toroidal Shape Magnetic Powder Core (토로이드형 분말코어의 Major B-H Loop 측정)

  • Son, Derac
    • Journal of the Korean Magnetics Society
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    • v.24 no.3
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    • pp.76-80
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    • 2014
  • Toroidal cores made of metallic powder requires large magnetic field strength up to few decade kA/m to obtain major hysteresis loop. To overcome thermal heat generation problem from large exciting current during measurement, we have employed a real time hysteresis loop tracer which can digitize and calculate B-H signals in personal computer as real time. For example, when we magnetize specimen at 10 Hz frequency, we could display hysteresis loops 10 times per second. Using the real time hysteresis loop tracer, we could measure major hysteresis loop of toroidal shape metallic powder core at maximum flux density or maximum magnetic field strength to be measured within 5 second not to significant increasement of specimen temperature due to the heat dissipation from coil windings. For the constructed hysteresis loop tracer, we could measure hysteresis loop at magnetic field strength higher than 50 kA/m for the toroidal shape specimen.

Precision Position Control of Piezoelectric Actuator Using Feedforward Hysteresis Compensation and Neural Network (히스테리시스 앞먹임과 신경회로망을 이용한 압전 구동기의 정밀 위치제어)

  • Kim HyoungSeog;Lee Soo Hee;Ahn KyungKwan;Lee ByungRyong
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.7 s.172
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    • pp.94-101
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    • 2005
  • This work proposes a new method for describing the hysteresis non-linearity of a piezoelectric actuator. The hysteresis behaviour of piezoelectric actuators, including the minor loop trajectory, are modeled by geometrical relationship between a reference major loop and its minor loops. This hysteresis model is transformed into inverse hysteresis model in order to output compensated voltage with regard to the given input displacement. A feedforward neural network, which is trained by a feedback PID control module, is incorporated to the inverse hysteresis model to compensate unknown dynamics of the piezoelectric system. To show the feasibility of the proposed feedforward-feedback controller, some experiments have been carried out and the tracking performance was compared to that of simple PTD controller.

Preisach Model of Shape Memory Alloy Actuators Using Proportional Relationship of The Major Loop of Hysteresis (히스테리시스 주 루프의 비례관계를 이용한 형상기억합금 엑츄에이터의 Preisach 모델)

  • Choe, Byeong-Jun;Lee, Yeon-Jeong;Choe, Bong-Yeol
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.9
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    • pp.736-746
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    • 2002
  • There has been a great demand for smart actuators in the field of micro-machines. However, the control accuracy of smart actuators, e.g., a shape memory alloy(SMA) and a piezoceramic actuator, is limited due to the inherent hysteresis nonlinearity. The Preisach hysteresis model has emerged as an appropriate model f3r the behavior of those smart actuators. Yet it is still not easy to construct a practical model of hysteresis using the classical Preisach model. Accordingly, in this paper, we propose a new simple method for modeling of the hysteresis nonlinearity of SMA. Using only the proportional relation of the major loop of hysteresis, the proposed method makes the computation of the Preisach model easy. We prove the efficacy of the proposed model through the comparative the experimentation with the classical Preisach model.

Hysteresis Compensation in Piezoceramic Actuators Through Preisach Model Inversion (Preisach 모델을 이용한 압전액츄에이터 이력 보상)

  • Chung C.Y.;Lee D.H.;Kim H.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1074-1078
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    • 2005
  • In precision positioning applications, such as scanning tunneling microscopy and diamond turning machines [1], it is often required that actuators have nanometer resolution in displacement, high stiffness, and fast frequency response. These requirements are met by the use of piezoceramic actuators. A major limitation of piezoceramic actuators, however, is their lack of accuracy due to hysteresis nonlinearity and drift. The maximum error due to hysteresis can be as much as 10-15% of the path covered if the actuators are run in an open-loop fashion. Hence, the accurate control of piezoceramic actuators requires a control strategy that incorporates some form of compensation for the hysteresis. One approach is to develop an accurate model of the hysteresis and the use the inverse as a compensator. The Preisach model has frequently been employed as a nonlinear model for representing the hysteresis, because it encompasses the basic features of the hysteresis phenomena in a conceptually simple and mathematically elegant way. In this paper, a new numerical inversion scheme of the Preisach model is developed with an aim of compensating hysteresis in piezoceramic actuators. The inversion scheme is implemented using the first-order reversal functions and is presented in a recursive form. The inverted model is then incorporated in an open-loop control strategy that regulates the piezoceramic actuator and compensates for hysteretic effects. Experimental results demonstrate satisfactory regulation of the position of the piezoceramic actuator to the desired trajectories.

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Core Loss Analysis of Non-oriented Electrical Steel Under Magnetic Induction Including Higher Harmonics

  • Cho, Chuhyun;Son, Derac;Cho, Youk
    • Journal of Magnetics
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    • v.6 no.2
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    • pp.66-69
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    • 2001
  • The actual magnetic induction waveform of cores in electrical machines is not sinusoidal i.e. higher harmonics are always included. Thus the core loss in actual electrical machines is different from the core loss which is measured by the standard method, because the waveform of magnetic induction should be sinusoidal in the standard testing method. Core loss analysis under higher harmonic induction is always important in electric machine design. In this works we measured the core loss when a hysteresis loop has only one period of an ac minor loop of higher harmonic frequency, depending on the position of the ac minor loop of relative to the fundamental harmonic frequency. From this experiment, the core loss P(B/sub 0/f/sub 0/, B/sub h/, nf/sub 0/)) under a higher harmonic magnetic induction B/sub h/ could be expressed by the linear combination the core loss at fundamental harmonic frequency P/sub c/(B/sub 0/, f/sub 0/), the core loss of ac minor loop at zero induction region of the major hysteresis loop P/sub cL/ (B/sub h/, nf/sub 0/), and the core loss of an ac minor loop in the high induction region of the major hysteresis loop P/sub cH/ (B/sub h/, nf/sub 0/) i.e., P/sub c/, (B/sub 0/, f/sub 0/, B/sub h/, nf/sub 0/)=P/sub c/ (B/sub 0/, f/sub 0/,)+(n-1)[k₁(B/sub 0/) P/sub cL/ (B/sub h/, nf/sub 0/)+(1-k₁(B/sub 0/)) P/sub cH/ (B/sub h/, nf/sub 0/)]. This will be useful formula for electrical machine designers and one of effective methods to predict core loss including higher harmonic induction.

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Identification of the Distribution Function of the Preisach Model using Inverse Algorithm

  • Koh, Chang-Seop;Ryu, Jae-Seop
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.2B no.4
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    • pp.168-173
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    • 2002
  • A new identification algorithm for the Preisach model is presented. The algorithm treats the identification procedure of the Preisach model as an inverse problem where the independent variables are parameters of the distribution function and the objective function is constructed using only the initial magnetization curve or only tile major loop of the hysteresis curve as well as the whole reversal curves. To parameterize the distribution function, the Bezier spline and Gaussian function are used for the coercive and interaction fields axes, respectively. The presented algorithm is applied to the ferrite permanent magnets, and the distribution functions are correctly found from the major loop of the hysteresis curve or the initial magnetization curve.

Perpendicular Magenetic Anisotropy in TbFeCo Magneto Optic Recording Thin Films

  • Lee, Yong-Ho-;Lee, Sang-Soo-
    • Proceedings of the Optical Society of Korea Conference
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    • 1988.06a
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    • pp.127-131
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    • 1988
  • In order to clarify the origin of perpendicular anisotropy in thermally evaporated TbFeCo amorphous thin films, we have investigated the effects of deposition angle on magnetic Kerr hysteresis loop, perpendicular magnetic anisotropy and internal stress depend strongly on the deposition angle and above a threshold value(30$^{\circ}$), the perpendicular anisotropy disapperars and the in-plane anisotropy appears. The measurement of internal stress is the major contribution to the perpendicular anisotropy. The measurements of Kerr hysteresis loops in the polar and the longitudinal directions show that as the deposition angle increases the polar kerr hystresis loop deteriorates while the longitudinal Kerr hystersis loop becomes prominent.

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Variation Pattern Analysis on the Air and Surface Water Temperatures of the Yellow Sea Monitoring Buoy (황해중부부이에서 관측된 기온 및 표층수온의 변화양상 분석)

  • Cho, Hong-Yeon;Jeong, Jin-Yong;Shim, Jae-Seol;Kim, Seon-Jeong
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.5
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    • pp.316-325
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    • 2010
  • Harmonic analyses are carried out in order to obtain the major frequency components of the air temperature (AT) and surface water temperature (SWT) data monitored in the Middle Area of the Yellow Sea (Yellow Sea monitoring buoy). The analysis shows the annual and semi-annual components are predominant and the higher frequency components are relatively weak with contribution to the short fluctuations, i.e. below $0.2{\sim}0.5^{\circ}C$, in the AT and SWT. The standard deviation of the AT residual is 2.4 times larger than that of the SWT residual and the occurrence frequency distributions of the AT and SWT residual components are both closely fitted to a normal-distribution function. The variation pattern on the AT-SWT plane forms the clear continuous hysteresis loop in anti-clockwise direction which is composed of the AT-SWT rising period, AT-SWT falling period, and the constant SWT period in winter season.

Seismic Response of Self-Centering Energy Dissipative Braced Frames (셀프센터링 가새골조의 지진응답)

  • Choi, Hyun-Hoon;Christopoulos, C.;Kim, Jin-Koo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2008.04a
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    • pp.331-336
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    • 2008
  • An self-centering energy-dissipative (SCED) bracing system has recently been developed as a new seismic force resistant bracing system. The advantage of the SCED brace system is that, unlike other comparable advanced bracing systems that dissipate energy, such as the buckling restrained brace system, it has a self-centering capability that reduces or eliminates residual building deformations after major seismic events. In this study seismic performance of SCED braced frames is evaluated for a set of 20 design level earthquake records. According to analysis results the SCED systems showed more uniform interstory drift demand for buildings with 8 story or fewer. The residual deformation in SCED buildings turned out to be much less than that of moment-resisting frames.

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A Study for the Formulation of the Preisach Distribution Function (프라이자흐 분포함수의 정식화에 관한 연구)

  • Kim, Hong-Kyu;Lee, Chang-Hwan;Jung, Hyun-Kyo;Hong, Sun-Ki
    • Proceedings of the KIEE Conference
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    • 1996.07a
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    • pp.56-58
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    • 1996
  • The Preisach model needs a density function to simulate the hysteresis phenomena. To obtain this function, many experimental data obtained from the first order transition curves are required to get accurate density function. However, it is difficult to perform this procedure, especially for the hard magnetic materials. In this paper, we compare the density function obtained from the experimental data with that computed from the mathematical function like the Gaussian function, and propose a simple technique to get mathematical equation of the density function or Everett function which is obtained from the initial curve, major and minor loop.

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