Feasibility and Application Study of Optical Voltage/Current Sensors Using FBG

This paper concludes the case study work on the optical sensor, which is a new method for voltage and current measurement. Fiber Bragg gratings (FBG) have been developed and used for decades in the telecommunication industry. In recent years, FBG sensors have found wide applications in monitoring strain, temperature, voltage and current across all industries. As the process of constructing a robust smart grid, thousands of miles of optical-fibers have been deployed along the power transmission lines for the purpose of power production communication. This paper focuses on using the power optical fiber as voltage/current sensors instead of those copper wired traditional current transformers. By using piezoelectric layers, the optical sensor is able to transform voltage/current magnitude into optical signal, as well as transmit the signal through the optical fiber. The application of using optical fiber will significantly reduce the cost of deploying traditional current transformers all around the power grid. Moreover, the optical sensor is more stable, more accurate and faster, with such characteristics, the smart grid monitoring system could be much better. The application of combining the optical composite low-voltage cable (OPLC) and the optical current sensor in the distribution network for smart distribution monitoring has been analyzed.

Torque Sharing Function Control of Switched Reluctance Machines with Reduced Current Sensors

This paper presents a Torque Sharing Function(TSF)control of Switched Reluctance Machines(SRMs)with different current sensor placements to reconstruct the phase currents.TSF requires precise phase current information to ensure accurate torque control.Two proposed methods with different chopping transistors or a new PWM implementation require four or two current sensors to replace the current sensors on each phase regardless of the phase number.For both approaches,the actual phase current can be easily extracted during the single phase conducting region.However,how to separate the incoming and outgoing phase current values during the commutation region is the difficult issue to deal with.In order to derive these two adjacent currents,the explanations and comparisons of two proposed methods are described.Their effectiveness is verified by experimental results on a four-phase 8/6 SRM.Finally,the approach with a new PWM implementation is selected,which requires only two current sensors for reducing the number of sensors.The control system can be more compact and cheaper.

Current sensor based on diamond nitrogen-vacancy color center

High precision current measurement is very important for the calibration of various high-precision equipment and the measurement of other precision detection fields.A new current sensor based on diamond nitrogen-vacancy(NV)color center magnetic measurement method is proposed to realize the accurate measurement of current.This new current method can greatly improve the accuracy of current measurement.Experiments show that the linearity of the current sensor based on diamond NV color center can reach up to 33 ppm,which is superior to other current sensors and solves the problem of low linearity.When the range of input current is 5-40 A,the absolute error of the calculated current is less than 51μA,and the relative error is 2.42×10^(-6) at 40 A.Combined with the research content and results of the experiment,the application of the current sensor in the field of current precision measurement is prospected.

Numeral eddy current sensor modelling based on genetic neural network

This paper presents a method used to the numeral eddy current sensor modelling based on the genetic neural network to settle its nonlinear problem. The principle and algorithms of genetic neural network are introduced. In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network （GNN） according to measurement data. So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network. The nonlinear model has the advantages of strong robustness, on-line modelling and high precision. The maximum nonlinearity error can be reduced to 0.037% by using GNN. However, the maximum nonlinearity error is 0.075% using the least square method.

Analysis of proton and γ-ray radiation effects on CMOS active pixel sensors

Radiation effects on complementary metal-oxide-semiconductor（CMOS） active pixel sensors（APS） induced by proton and γ-ray are presented. The samples are manufactured with the standards of 0.35 μm CMOS technology. Two samples have been irradiated un-biased by 23 MeV protons with fluences of 1.43 × 10^11 protons/cm^2 and 2.14 × 10^11 protons/cm-2,respectively, while another sample has been exposed un-biased to 65 krad（Si） ^60Co γ-ray. The influences of radiation on the dark current, fixed-pattern noise under illumination, quantum efficiency, and conversion gain of the samples are investigated. The dark current, which increases drastically, is obtained by the theory based on thermal generation and the trap induced upon the irradiation. Both γ-ray and proton irradiation increase the non-uniformity of the signal, but the nonuniformity induced by protons is even worse. The degradation mechanisms of CMOS APS image sensors are analyzed,especially for the interaction induced by proton displacement damage and total ion dose（TID） damage.

Current-voltage characteristics of lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composites

Current--voltage measurements obtained from lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composite showed that a sinusoidal current applied to the copper coil wrapped around the hollow cylinder circumference induces voltage across the lead zirconate titanate layer thickness. The current--voltage coefficient and the maximum induced voltage in lead zirconate titanate at 1~kHz and resonance （60.1~kHz） frequencies increased linearly with the number of the coil turns and the applied current. The resonance frequency corresponds to the electromechanical resonance frequency. The current--voltage coefficient can be significantly improved by optimizing the magnetoelectric structure geometry and/or increasing the number of coil turns. Hollow cylindrical lead zirconate titanate/nickel structures can be potentially used as current sensors.

A New Modeling Method Based on Genetic Neural Network for Numeral Eddy Current Sensor

In this paper,we present a method used to the numeral eddy current sensor modeling based on genetic neural network to settle its nonlinear problem.The principle and algorithms of genetic neural network are introduced.In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network (GNN) according to measurement data.So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network.The nonlinear model has the advantages of strong robustness,on-line scaling and high precision.The maximum nonlinearity error can be reduced to 0.037% using GNN.However,the maximum nonlinearity error is 0.075% using least square method (LMS).

A Passive Optical Fiber Current Sensor Based on YIG

A research on passive optical fiber current sensor based on magneto-optical crystal and a new design of light path of the sensor head are presented. Both methods of dual-channel optical detection of the polarization state of the output light and signal processing are proposed. Signal processing can obtain the linear output of the current measurement of the wire more conveniently. Theoretical analysis on the magnetooptical fiber current sensor is given, followed by experiments. After that, further analysis is made according to the results, which leads to clarifying the exiting problems and their placements.

YbBi:YIG石榴石单晶的磁光性能及其光纤电流传感器应用

Magneto optic(MO) fiber current sensors utility the Faraday effect of magneto op tic materials to sensing the magnetic(current)fields.The optical fiber sensors(O FS)offer great advantages of simple structure,high reliability,high accuracy and sensibility,immunity to electromagnetic interference.They are the most promised method to substitute the conventional current transducers(CTs),much attentions were focused on both domestic and abroad.Magneto optic properties of Faraday se n sing element have much affect on the performance of the optical fiber current se nsor.For used in the sensor system,MO materials with magneto optic characterist i cs of large Faraday rotation(FR)angle θ f ,low temperature sensibility,and suitable saturation field were general demanded. Development of MO materials is one of the most important problems of optical fiber current sensor research. In this paper,one mixed doped Bi substituted yttrium iron garnet crystal BiYb:Y I G, which has large and temperature stable FR angle,was grown from high temperatu re flux.By taking PbO+PbF 2 as the main flux,under the compositions of molar ra tio Y 2O 3:Yb 2O 3:Bi 2O 3:Fe 2O 3:(PbO+PbF 2+B 2O 3+CaCO 3)=7.64:1. 04:1.74:20.78:78:68.8,crystals of quite good quality were grown from melt flux,t he largest one has the size of 22mm×15mm×12mm.Magneto optic proprieties of Fa raday rotation angle and optical absorption spectrum of the BiYb:YIG crystal,expecial ly Y 2.289 Yb 0.246 Bi 0.465 Fe 5O 12 ,in the range of 0.7 1.9 μm waveband were measured.At λ =1.55μm,the BiYb:YIG crystal has special Fa raday rotation angle of -404deg/cm,temperature coefficient 4.2×10 -6 K -1 ,optical absorption coefficient 3.6cm -1 ,and figure of merit 25.8deg/dB . The results indicate that substituted with Bi 3+ can largely improve the Fa raday rotation of rear earth iron garnets.Because Faraday rotation angles of Yb 3Fe 5O 12 and Y 3Fe 5O 12 have opposite temperature dependency,ut ility the compensation effect of mix doped,co doped with some other ions,such a s Yb 3+ ,would decrease the temperature dependency of Bi substituted garnet. So the garnet crystal BiYb:YIG has high and temperature stable Faraday rotation an gle,very suitable to be used as Faraday effect materials for high sensibility an d temperature stable Optical fiber current sensors.Using BiYb:YIG as Faraday rot ation cell,a hybrid bulk crystal optical fiber current sensor was proposed and t ests under direct current(DC) and 50Hz alternating current(AC).The performance c haracteristics of the sensors system were:DC measurement,sensibility 0.01A, l inea rity 1.1%;AC measurement,sensibility 9.5A/mV ,accuracy ±1%,linearity 1.1%,dynam ic range 40dB.In conclusion,Faraday effect magneto optic optical fiber current sensors have higher sensibility and accuracy than conventional CTs.

HIGH TEMPERATURE DISPLACEMENT SENSOR

A high temperature displacement sensor based on the principle of eddy-current is investigated. A new temperature compensation technique by using eddy-current effect is presented to satisfy the special requirement at high temperature up to 550℃. The experiment shows that the temperature compensation technique leads to good temperature stability for the sensors. The variation of the sensitivity as well as the temperature drift of the sensor with temperature compensation technique is only about 7.4% and 90-350 mV at 550 ℃ compared with that at room temperature, and that of the sensor without temperature compensation technique is about 31.2% and 2-3 V at 550 ℃ compared with that at room temperature. A new dynamic calibration method for the eddy-current displacement sensor is presented, which is very easy to be realized especially in high frequency and at high temperatures. The high temperature displacement sensors developed are successfully used at temperature up to 550 ℃ in a magnetic bearing system for more than 100 h.

Parameter Optimization and Precision Enhancement of Dual-Coil Eddy Current Sensor

To enhance the measurement precision of eddy current sensor in particular environments such asextreme temperature changes and limited available space in aerospace, we optimized the structural parameters ofthe traditional dual-coil eddy current sensor probe by electromagnetic field analysis and finite element simulationmodeling, and further presented the criteria for determining the optimal coil distance of the dual-coil probe. Thesimulation results are verified by setting up an experimental platform. For the extreme temperature environment,the displacement measurement error caused by the full range temperature variation of the dual-coil sensor underthe optimal distance is less than 21.0% of that of the single-coil sensor. On this basis, we analyzed and verified thethermal stability of the structurally optimized dual-coil eddy current sensor. After temperature compensation,the displacement measurement accuracy can reach 14.9 times more accurate than that of the single-coil sensor.The method proposed in this paper can provide a design reference for the structural optimization of the axialdual-coil eddy current sensor probe.

Investigating Averaging Effect by Using Three Dimension Spectrum

The eddy current displacement sensor＇s averaging effect has been investigated in this paper, and the frequency spectrum property of the averaging effect was also deduced. It indicates that the averaging effect has no influences on measuring a rotor＇s rotating error, but it has visible influences on measuring the rotor＇s profile error. According to the frequency spectrum of the averaging effect, the actual sampling data can be adjusted reasonably, thus measuring precision is improved.

Fiber structures and material science in optical fiber magnetic field sensors

Magnetic feld sensing plays an important role in many felds of scientifc research and engineering applications.Benefting from the advantages of optical fbers,the optical fber-based magnetic feld sensors demonstrate characteristics of light weight,small size,remote controllability,reliable security,and wide dynamic ranges.This paper provides an overview of the basic principles,development,and applications of optical fber magnetic feld sensors.The sensing mechanisms of fber grating,interferometric and evanescent feld fber are discussed in detail.Magnetic fuid materials,magneto-strictive materials,and magneto-optical materials used in optical fber sensing systems are also introduced.The applications of optical fber magnetic feld sensors as current sensors,geomagnetic monitoring,and quasi-distributed magnetic sensors are presented.In addition,challenges and future development directions are analyzed.

Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor

A current-mode PWM buck DC-DC converter is proposed. With the high-accuracy on-chip current sen- sor, the switching frequency can be selected automatically according to load requirements. This method improves efficiency and obtains an excellent transient response. The high accuracy of the current sensor is achieved by a simple switch technique without an amplifier. This has the direct benefit of reducing power dissipation and die size. Additionally, a novel soft-start circuit is presented to avoid the inrush current at the starting up state. Finally, this DC-DC converter is fabricated with the 0.5μm standard CMOS process. The chip occupies 3.38 mm2. The accuracy of the proposed current sensor can achieve 99.5% @ 200 mA. Experimental results show that the peak efficiency is 91.8%. The input voltage ranges from 5 to 18 V, while a 2 A load current can be obtained.

A passive current sensor employing self-biased magnetoelectric transducer and high-permeability nanocrystalline flux concentrator

A passive current sensor,consisting of SmFe_(2)/PZT/SmFe_(2)self-biased magnetoelectric(ME)composite and Fe_(73.5)Cu_(1)Nb_(3)Si_(13.5)B_(9)nanocrystalline flux concentrator for weak current detection at power-line frequency,was fabricated and characterized.Giant magnetostrictive material of SmFe_(2)plate with large anisotropic constant provides a huge internal anisotropic field to bias the ME transducer in closed magnetic loop.Consequently,the additional magnetomotive force induced by the internal field and the corresponding increased effective permeabil-ity contribute to the improvement of the sensitivity.Experimental results demonstrate that the presented sensor has a higher sensitivity of 152 mV·A^(-1)at 50 Hz with a slight nonlinearity of~0.01%full scale(FS)and matches well with the predicted value.This presented current-sensing device exhibits approximately 2.3 times higher sensitivity than that of conventional ME composite with[Pb(Zr_(0.48),Ti_(0.52)O_(3)](PZT)and Terfenol-D plates serving as a key sensitive component.In addition,time stabilities of the presented sensor were evaluated for a long period of 72 h and analyzed through mathematical statistics method,and favorable stabilities with an uncertainty of 0.5μV are obtained in continuous 1 h testing.These results provide a significant advancement toward promising application of the tri-layer self-biased ME laminate for power-line elec-tric cords monitoring.

Limiting current oxygen sensor based on Y,In co-doped SrTiO_(3)as a dense diffusion barrier layer

A novel dense diffusion barrier material(Y_(x)Sr_(1−x)Ti_(0.9)In_(0.1)O_(3−δ)(x=0.03,0.05,0.07))was prepared by using a sol-gel method.The crystal structure,microstructures,electrical conductivity and ionic conductivity of barrier material were characterized.The results show that the samples exhibit the formation of cubic perovskite structure phase.The increase of Y-doping amount on A-site improved electrical conductivity and sinterability of materials.A limiting current oxygen sensor based on Y_(0.07)Sr_(0.97)Ti_(0.9)In_(0.1)O_(3–δ)as a dense diffusion barrier shows excellent sensing performance.The linear relationship between limiting current logIL and 1000/T can described logIL=4.603,8−3.847,5·1,000/T.At 750°C,0.25%≤x(O_(2))≤5.0%,the linear relationship between limiting current(IL)and oxygen amount(x(O_(2)))can described as I_(L)=7.047,6+3.875,1·x(O_(2)).

Study of silicon pixel sensor for synchrotron radiation detection

The silicon pixel sensor（SPS） is one of the key components of hybrid pixel single-photon-counting detectors for synchrotron radiation X-ray detection（SRD）. In this paper, the design, fabrication, and characterization of SPSs for single beam X-ray photon detection is reported. The designed pixel sensor is a p＋-in-n structure with guard-ring structures operated in full-depletion mode and is fabricated on 4-inch, N type, 320 μm thick, high-resistivity silicon wafers by a general Si planar process. To achieve high energy resolution of X-rays and obtain low dark current and high breakdown voltage as well as appropriate depletion voltage of the SPS, a series of technical optimizations of device structure and fabrication process are explored. With optimized device structure and fabrication process,excellent SPS characteristics with dark current of 2 n A/cm^2, full depletion voltage 〈 50 V and breakdown voltage〉 150 V are achieved. The fabricated SPSs are wire bonded to ASIC circuits and tested for the performance of X-ray response to the 1W2 B synchrotron beam line of the Beijing Synchrotron Radiation Facility. The measured S-curves for SRD demonstrate a high discrimination for different energy X-rays. The extracted energy resolution is high（〈 20% for X-ray photon energy 〉 10 keV） and the linear properties between input photo energy and the equivalent generator amplitude are well established. It confirmed that the fabricated SPSs have a good energy linearity and high count rate with the optimized technologies. The technology is expected to have a promising application in the development of a large scale SRD system for the Beijing Advanced Photon Source.