共查询到20条相似文献,搜索用时 31 毫秒
1.
The demagnetizing current I
dc is measured in different areas of an electromagnet-article magnetic circuit at the moment of zero crossing of the magnetic
flux as the gap between the electromagnet and article changes. The weaker dependence of the I
dce magnitude measured in close proximity to the article on the gap width and the possibility of using the parameter in measuring
the coercive force of the article with an attachable transducer (in particular, with a Hall sensor) are demonstrated. 相似文献
2.
Dependences of the magnetic-field strength of flaws on a electromagnet’s current and the magnetic induction in a magnetic-circuit gap are obtained. The magnetic-field strength of flaws in magnetically hard steels is found to be higher than that of flaws in magnetically soft steels. The results obtained are explained in terms of the demagnetizing action of a surface magnetic dipole as well as the dependence of the magnetic-flux distribution over specimens on the magnetic permeability of a material and on the induction under the electromagnet’s poles. 相似文献
3.
E. S. Gorkunov A. M. Povoltskaya K. E. Solov’ev S. M. Zadvorkin 《Russian Journal of Nondestructive Testing》2010,46(9):638-644
Hysteretic magnetic properties and longitudinal magnetostriction of planar specimens of air-hardened 45 steel were measured
as functions of elastic tensile stresses along and perpendicular to the applied loading using a closed magnetic circuit and
attachable transducers. Parameters that exhibit monotonic variations with increasing elastic tensile stresses, were found.
It was shown that the maxima that were observed in the dependences of residual inductance and relative maximum magnetic permeability
on applied stresses, as well as the minima that were observed in the dependences of the coercive force and demagnetizing current
of an attachable electromagnet as measured with a sensor arranged along the tension axis on applied stresses, are related
to the behavior of the magnetostriction curves of the steel under study. 相似文献
4.
Currently, most researches use signals, such as the coil current or voltage of solenoid, to identify parameters; typically, parameter identification method based on variation rate of coil current is applied for position estimation. The problem exists in these researches that the detected signals are prone to interference and difficult to obtain. This paper proposes a new method for detecting the core position by using flux characteristic quantity, which adds a new group of secondary winding to the coil of the ordinary switching electromagnet. On the basis of electromagnetic coupling theory analysis and simulation research of the magnetic field regarding the primary and secondary winding coils, and in accordance with the fact that under PWM control mode varying core position and operating current of windings produce different characteristic of flux increment of the secondary winding. The flux increment of the electromagnet winding can be obtained by conducting time domain integration for the induced voltage signal of the extracted secondary winding, and the core position from the two-dimensional fitting curve of the operating winding current and flux-linkage characteristic quantity of solenoid are calculated. The detecting and testing system of solenoid core position is developed based on the theoretical research. The testing results show that the flux characteristic quantity of switching electromagnet magnetic circuit is able to effectively show the core position and thus to accomplish the non-displacement transducer detection of the said core position of the switching electromagnet. This paper proposes a new method for detecting the core position by using flux characteristic quantity, which provides a new theory and method for switch solenoid to control the proportional valve. 相似文献
5.
Ďuran I Bolshakova I Viererbl L Sentkerestiová J Holyaka R Lahodová Z Bém P 《The Review of scientific instruments》2010,81(10):10E122
We report on irradiation tests of InSb based Hall sensors at two irradiation facilities with two distinct types of neutron spectra. One was a fission reactor neutron spectrum with a significant presence of thermal neutrons, while another one was purely fast neutron field. Total neutron fluence of the order of 10(16)?cm(-2) was accumulated in both cases, leading to significant drop of Hall sensor sensitivity in case of fission reactor spectrum, while stable performance was observed at purely fast neutron spectrum. This finding suggests that performance of this particular type of Hall sensors is governed dominantly by transmutation. Additionally, it further stresses the need to test ITER candidate Hall sensors under neutron flux with ITER relevant spectrum. 相似文献
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E. S. Gorkunov A. M. Povolotskaya K. E. Solov’ev S. M. Zadvorkin 《Russian Journal of Nondestructive Testing》2009,45(8):521-525
Attachable transducers were used to measure the demagnetizing current, which is proportional to the coercive force, and Barkhausen
noise parameters for steel 45 specimens depending on the degree of their plastic deformation in measuring the magnitudes along
and perpendicular to the tension direction. The demagnetizing current measured along the preliminary tension direction was
shown to increase monotonically; the rate of its changes is maximal at the initial stage of plastic deformation. The demagnetizing
current measured perpendicular to the applied tension direction also increases monotonically but within a narrower range.
Near local inhomogeneities formed during the deformation, substantial changes in the coercive force and Barkhausen noise take
place. The results obtained are explained on the basis of the current concept of the anisotropy of internal stresses in preliminarily
plastically deformed materials. 相似文献
9.
V. N. Kostin T. P. Tsar'kova E. Yu. Sazhina 《Russian Journal of Nondestructive Testing》2001,37(1):10-19
The paper is dedicated to the feasibility of measurements of magnetic parameters of tested components incorporated in closed circuits with ferromagnetic transducers in the capacity of magnetic flux meters and the technique based on the conversion of the measured flux to a magnetic field intensity in an opening of a certain configuration made in the magnetic conductor of an applied electromagnet. 相似文献
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Modeling and experimental studies of the spatial distributions of the field and flux inside and above the surface of ferromagnetic plates of different dimension types, which were locally magnetized by U-shaped electromagnets, were performed. It was established that the location of a magnetic inhomogeneity in the interpole zone of an electromagnet substantially affects the results of a local measurement of the coercive force using a demagnetization current. It is shown that the presence of a gap in the magnetic circuit impairs the magnetization of the interpole zone of an object to a higher degree than the magnetization of the near-pole zone. Recommendations on the concentration of the magnetic flux in the interpole zone via a decrease in the interpole distance of the electromagnet are given. Possible locations of internal-field probes that provide local measurements of the magnetic properties of a substance are determined. 相似文献
12.
Resolvers are normally employed for rotor positioning in motors for electric vehicles,but resolvers are expensive and vulnerable to vibrations.Hall sensors have the advantages of low cost and high reliability,but the positioning accuracy is low.Motors with Hall sensors are typically controlled by six-step commutation algorithm,which brings high torque ripple.This paper studies the high-performance driving and braking control of the in-wheel permanent magnetic synchronous motor(PMSM) based on low-resolution Hall sensors.Field oriented control(FOC) based on Hall-effect sensors is developed to reduce the torque ripple.The positioning accuracy of the Hall sensors is improved by interpolation between two consecutive Hall signals using the estimated motor speed.The position error from the misalignment of the Hall sensors is compensated by the precise calibration of Hall transition timing.The braking control algorithms based on six-step commutation and FOC are studied.Two variants of the six-step commutation braking control,namely,half-bridge commutation and full-bridge commutation,are discussed and compared,which shows that the full-bridge commutation could better explore the potential of the back electro-motive forces(EMF),thus can deliver higher efficiency and smaller current ripple.The FOC braking is analyzed with the phasor diagrams.At a given motor speed,the motor turns from the regenerative braking mode into the plug braking mode if the braking torque exceeds a certain limit,which is proportional to the motor speed.Tests in the dynamometer show that a smooth control could be realized by FOC driving control and the highest efficiency and the smallest current ripple could be achieved by FOC braking control,compared to six-step commutation braking control.Therefore,FOC braking is selected as the braking control algorithm for electric vehicles.The proposed research ensures a good motor control performance while maintaining low cost and high reliability. 相似文献
13.
Anthony Simm Theodoros Theodoulidis Nikolaos Poulakis Gui Yun Tian 《The International Journal of Advanced Manufacturing Technology》2011,54(1-4):223-230
Eddy current testing is one of the most widely used methods in non-destructive testing for the inspection of conductive materials. Numerical modelling of eddy current testing has emerged as an important approach alongside experimental studies. This paper investigates an application of numerical modelling and experimental study as a means of the quantitative non-destructive evaluation (QNDE) of defects in conductive samples. There are two methods of measuring eddy current response, more commonly by measuring the change in impedance of the eddy current probe coil, or as used in this work, by measuring the change in magnetic field directly using magnetic field sensors such as superconducting quantum interference devices, giant magneto resistance, or as in this case Hall sensors. Specifically, measurements made using an eddy current probe containing an excitation coil and a Hall sensor, experimentally obtained using an X?CY scanner table, are compared with a numerical (finite element method) model. The discrepancies between the experimental tests and the numerical models have been analysed and explained, which is an important factor in engineering applications of QNDE. 相似文献
14.
建立直流螺管式电磁阀数学模型,并用有限元法对电磁阀进行了求解。得到电磁场的磁力线、磁通密度等参数的分布规律及动铁心的力与行程的关系。与实际测试的吸力基本吻合,相对误差为4.2%。为电磁阀的设计提供理论依据。 相似文献
15.
为实现高速磁浮轨道长定子行波主漏磁场小空间、mT量级磁梯度张量的准确测量,将图像边缘检测领域的Prewitt梯度算子进行实例化,设计了一种由8只霍尔磁敏传感器构成的小体积、低成本的磁梯度张量测量结构。通过空间冗余的手段,克服了霍尔磁敏传感器零点偏移大,灵敏度一致性差的特点,也为传统磁梯度张量测量系统传感器的空间布局提供了一种新的思路。实验结果表明,相对传统十字形、正方形结构,Prewitt结构可将多传感器上述两种参数不一致导致的测量误差分别减小至原来的-10.4%和58.1%,有效降低了测量系统对传感器参数一致性的要求,避免了复杂高成本的三轴传感器标定与误差校正环节。 相似文献
16.
新型霍尔传感器在电流检测中的应用 总被引:10,自引:0,他引:10
相对于传统的集成霍尔传感器,磁集极霍尔传感器具有高线性度、低磁滞、高灵敏度、体积小、价格低等优点。随着该技术的推广,磁集极霍尔传感器必将广泛应用于很多领域。介绍了磁集极霍尔传感器检测电流的基本原理及应用,并且提出了对于不同范围电流检测的解决办法。 相似文献
17.
Based on electromagnetic flux leakage (EMFL), a nondestructive testing (NDT) technique for the detection of gas pipe wall thickness is presented, and its principle and feasibility is evaluated by means of equivalent magnetic circuit analysis and finite element analysis. An online NDT device adopting this technique is developed, and its structure and working principle are introduced in detail. This device is composed of a detector array with 32 pipe wall thickness sensors that employ a Hall element as the element for sensing the magnetic flux density, and it can be adapted to pipe diameters from Ø400mm to Ø650 mm. On the basis of the experimental investigation for this device, the influences of some factors on thickness measurement, namely the excitation current, excitation coil turns, gap distance, concentrator of the magnetic field, magnetization time, and number of sensors in the detector array, are revealed and the optimal excitation voltage for the sensors of the detector array is selected. The measuring calibration is given to establish the relationship between the pipe wall thickness and the output voltage of the sensors. The results show that the proposed EMFL for measuring the wall thickness of ferromagnetic pipe is feasible, the technical parameters of the sensor are important for improvement of measurement precision and resolution, and the developed device has precision, resolution, and a linear output curve. Carried by the developed gas pipeline inspection robot through a universal joint, this NDT device can move inside the gas pipeline and monitor the state of the pipe wall. 相似文献
18.
R. Kaneko 《Journal of microscopy》1988,152(2):363-369
Frictional forces are usually measured by detecting spring displacement. To obtain high-resolution measurements of frictional force distributions, a sharp tip and a light load are required. In measuring frictional force on relatively rough surfaces, using very sharp tips (submicron radii), significant stick-slip motions are observed, and continuously varying dynamic frictional forces can not be measured. To measure continuous friction distributions between sharp tips and surfaces with light loads, a new frictional force microscope (FFM) is developed. This FFM has an electromagnet to maintain the tip suspension spring in a non-deflected position. The frictional force is then measured from the magnet current. Using this FFM, continuous friction distributions between 0·1 μm radius diamond tips and magnetic disk surfaces with light loads (less than 10 μN) are obtained. 相似文献
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This paper presents the design of a new 3-D Hall sensor compatible with standard silicon IC technology and optimization of its characteristics through originally realized amperometric scheme. This magnetic Hall effect sensor is intended to be fitted at the tip of a catheter for use in a magnetic-based navigation system for endovascular interventions. Unfortunately, at present the general feeling is that vector Hall sensors cannot be used for clinical trials, mainly because of their large size and low sensitivity. Proposed 3-D silicon Hall sensor has denied suspicions with its advantages: simultaneous on line 3-D measurement of the magnetic field components; high spatial resolution 150 μm × 150 μm × 100 μm; the lowest detected magnetic induction of the three output channels is about 15/20 μT; magnetosensitivities of the three channels at a supply current 10 mA reach 360 μA/T for Bx and By, 250 μA/T for Bz, respectively. 相似文献