Voltage Measurement Technique Research Articles

Online estimation of state-of-charge using auxiliary load

Numerous approaches and methodologies have been established for online (while the load is supplied) estimation of the State-of-Charge of Lithium-ion cells and batteries. However, as battery load consumption fluctuates in real time because of delivered device operations, obtaining a precise online state of charge estimation remains a challenging task. This work proposes a new technique for online open circuit voltage measurement to estimate state of charge of batteries. This novel technique proposes the addition of an auxiliary regulated load that may be utilized to temporarily force specifically defined forms of the battery's current curve under particular conditions, which results in improving and simplifying online open circuit voltage computations. The effectiveness of the proposed technique was successfully validated through several experimental tests. The acquired findings demonstrated its efficiency with an acceptable online state of charge estimation accuracy. Typically, an estimation error of less than 2% was recorded in most tests, while the error was less than 1% when the battery’s state of charge was high.

Crack detection using a cutting-edge flexible eddy current sensor with voltage and phase measurement techniques

This study utilizes cutting-edge Flexible Eddy Current (FEC) sensors for the detection of cracks in aluminum plates with varying artificial crack sizes. The FEC sensor, relying on voltage and phase correction measurements, analyzes and processes signals from these cracks. The results demonstrate that excitation frequency and current have a significant impact on the induced current voltage and phase in the detection coil. Increasing these parameters linearly amplifies voltage, while phase changes primarily depend on the excitation frequency. To address phase change with large cracks, the phase correction method was employed, improving clarity for more accurate assessments. The study highlights the sensitivity of the FEC sensor in detecting cracks of various sizes, including subtle changes in voltage and phase for small cracks. Additionally, phase measurements, especially at higher excitation frequencies, offer better sensitivity and resolution. The study is also placed on the importance of scanning speed in acquiring crack data, as higher speeds may reduce data points and affect interpretation, requiring careful consideration.

CuO NWs boosted triboelectric microfluidic nanosensor functionalized by collagen-protein interactions for real-time platelet count monitoring

Blood platelet count significantly affects the development of severe conditions like myocardial infarction, peripheral arterial ischemia, respiratory compromise, stroke, diabetes, coronavirus disease 2019 (COVID-19), along with chemotherapy patients and those suffering cardiovascular diseases (CVDs). These conditions necessitate frequent monitoring of platelet counts to guide diagnostic and therapeutic decisions. However, existing techniques are relatively time-consuming, lack of accuracy and require precise operation. The emergence of these severe diseases underscored the need to develop advanced platelet count-monitoring techniques which are rapid, highly precise, and conveniently portable for point-of-care applications. In this study, we emphasized the development of a triboelectric microfluidic nanosensor (TMNS) for platelet quantification through the assessment of flow resistance. The functionality of TMNS device is based on immobilization of platelets on a collagen layer coated inside a microfluidic channel. The triboelectric voltage output is measured as a detection signal of the flow resistance and is enhanced by incorporating high surface area copper oxide nanowires (CuO NWs) on the interior of copper tubes. These copper tubes serve as terminal electrodes and for flow guiding. The flow resistance of plasma solutions is elevated when the platelet concentration increases due to heightened adherence of platelets onto the collagen layer. Variations in flow resistance induce alterations in contact electrification, causing changes in output voltage at load terminals. Fine-tuning of the TMNS device was achieved by optimizing the channel width and length, flowing liquid viscosity, and voltage measurement technique. Platelet quantification sensing data were acquired through the combination of platelet-rich plasma (PRP) and platelet-poor plasma (PPP) solutions. The described device exhibits promising capabilities for platelet-count monitoring in whole-blood samples collected from three distinct patient groups, showcasing its potential impact in precise point-of-care applications.

Current-induced switching of a van der Waals ferromagnet at room temperature

Recent discovery of emergent magnetism in van der Waals magnetic materials (vdWMM) has broadened the material space for developing spintronic devices for energy-efficient computation. While there has been appreciable progress in vdWMM discovery, a solution for non-volatile, deterministic switching of vdWMMs at room temperature has been missing, limiting the prospects of their adoption into commercial spintronic devices. Here, we report the first demonstration of current-controlled non-volatile, deterministic magnetization switching in a vdW magnetic material at room temperature. We have achieved spin-orbit torque (SOT) switching of the PMA vdW ferromagnet Fe3GaTe2 using a Pt spin-Hall layer up to 320 K, with a threshold switching current density as low as Jsw=\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${J}_{{{{{{\\rm{sw}}}}}}}=$$\\end{document}1.69 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 106 A cm−2 at room temperature. We have also quantitatively estimated the anti-damping-like SOT efficiency of our Fe3GaTe2/Pt bilayer system to be ξDL=0.093\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\xi }_{{{{{{\\rm{DL}}}}}}}=0.093$$\\end{document}, using the second harmonic Hall voltage measurement technique. These results mark a crucial step in making vdW magnetic materials a viable choice for the development of scalable, energy-efficient spintronic devices.

Modulation of electrical properties of sputtered Ta2O5 films by variation of RF power and substrate temperature

Dielectric thin films are important building blocks of microelectronic devices, and hence, research on the development of high-k dielectric thin films has drawn tremendous research interest. In this research, thin films of tantalum oxide (Ta2O5), a high-k dielectric material, are deposited on the Si substrate by the radio frequency (RF) magnetron sputtering technique. During the deposition of Ta2O5 thin film, the sputtering parameters such as sputtering power and substrate temperature were systematically varied, and post-deposition structural, morphological, and electrical properties of sputtered Ta2O5 films are studied by x-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscope, capacitance–voltage (C-V) and current–voltage (I-V) measurement techniques. The annealed Ta2O5 thin film at the temperature of 900 °C for 1 h possesses polycrystalline nature with β—phase orthorhombic crystal structure. The film deposited at 150 W and substrate temperature at room temperature has shown comparatively lower surface roughness, which depicts the energy, and mobility of adatoms greatly influenced by RF power and substrate temperature. With the increase in sputtering power, the oxide charge density (Qox) is found to increase. On the other hand, Qox is found to decrease with the increase in substrate temperature. The film deposited at RF power of 150 W and substrate temperature of 300 °C is found to be of high dielectric constant, low oxide and interface charge density, and lower leakage current.

A straightforward DC-reversal method for the Thomson coefficient measurement

DC reversal is a widely used technique for precise voltage measurement to remove DC offsets from the measurement signals. Herein, we propose a straightforward method using a DC reversal for the thermoelectric Thomson effect measurements. The proposed method allows the determination of Thomson coefficient from readily measurable quantities, that is, DC resistance, current, and the temperature changes caused by the Joule and Thomson effects, thereby removing the requirement of information on thermal conductivity and geometric values, which are required in a traditional DC-reversal method. Furthermore, this DC-based approach avoids typical complications experienced in recently developed AC-based methods, such as the absence of an AC current source or lock-in amplifier. The experimental results show that the Thomson coefficient of a fine Pt wire measured using the proposed method agrees well with a previously reported reference measurement with the expanded relative uncertainty of 6 %.

Self-Heating of Annealed Ti/Al/Ni/Au Contacts to Two-Dimensional Electron Gas in AlGaN/GaN Heterostructures

In this work, we investigated the self-heating effects of annealed Ti/Al/Ni/Au ohmic contacts and two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures under strong electric field by using the short pulse current–voltage and microwave noise measurement techniques. The experimental results demonstrated that the self-heating phenomena in ohmic contacts with the increase of current may dominate over the electrical performances of 2DEG channel. Moreover, the excess noise temperature of contact resistance was found to be more than four times higher than that of 2DEG channel at the same high current density values. The results reveal the importance of self-heating of the ohmic contacts on the device performance under short-duration (only 100 ns) and low-duty-cycle (only 10−5) pulse regime.

Non-contact Voltage Measurement Technique for On-Line Monitoring of Transient Overvoltages

The electric power system is continuously growing in its size, complexity and required reliability. There is an increased risk due to transient overvoltages which can deteriorate the insulation for different power system components. There is a need for monitoring of transient voltages to better monitor the effects due to them on the insulation of the components. It can be achieved using a non-contact voltage measurement technique. The study elucidates the theory and practical application of the non-contact voltage measurements. The measurement of voltage is achieved by utilizing the stray parasitic capacitance between the high voltage conductor and the ground. A metal plate is used as a sensor to detect the voltage, which indirectly acts as a capacitance divider for voltage measurement. The current study uses operational amplifier based differential-integrator circuit topology in order to accurately measure the voltage over a wide bandwidth of 20 Hz - 1 MHz. The measurement technique is used for measurement of three phase voltages and a methodology is proposed for it. The sensor system is also tested in an online test scenario in a substation for monitoring the shunt reactor switching transients.

Determination of voltage at the rectifier installation of the electric locomotive VL-80K for each position of the controller driver's

The object of research is the electrical processes in the control system of the traction drive of the electric locomotive VL-80K (Russia). To improve the accuracy of its mathematical model, it is necessary to use the values of the parameters determined during experimental studies of the traction drive control system. In particular, it is important to use in the traction drive model the value of the voltages on the arms of the rectifier installation of the electric locomotive, taking into account the position of the driver's controller. The complexity of the simulation lies in the fact that the reference does not provide the value of the voltage on the arms of the rectifier for each position of the driver's controller, which makes it difficult to verify the resulting model. A scheme for measuring the voltage value on the arms of the rectifier installation of an electric locomotive for each position of the position of the driver's controller is proposed. On its basis, a simulation model is developed in the MATLAB software environment. The simulation model implements an algorithm for closing the contactors of the electric group contactor for each position of the position of the driver's controller. Approbation of the voltage measurement technique was carried out on an electric locomotive of the VL-80K series during a trip on the Darnytsia-Myronivka section (Ukraine). Comparison of the voltage values on the arms of the rectifier installation, obtained experimentally, with the passport data showed that the measurement error was 0.5 %. In addition, the experimental results showed that the voltages on the arms of the rectifier for paired positions of the position of the driver's controller are the same, for odd ones they are different. Therefore, when simulating the operation of the traction drive control system, the voltage values on different arms of the rectifier installation were taken separately. Comparison of the simulation results for the nominal mode with passport data showed that for this mode the measurement error was 3.78 %. For all others, it did not exceed 5 %.

In-plane crystallographic orientations related spin-orbit torque in epitaxial Pt(111)/Co/Ta heterostructures

Current induced spin–orbit torque (SOT) in heavy metals with strong spin–orbit coupling strength has attracted considerable attention due to its potential applications in spintronic technology. Pt, as one of the mostly used heavy metals in SOT-based spintronic devices, shows large spin Hall angle (θSH) with its single phase and alloy counterparts. In this work, the in-plane crystallographic orientations related θSH of epitaxial Pt(111) layer is reported in MgO(111)/Pt(111)/Co/Ta heterostructures with strong perpendicular magnetic anisotropy. The θSH shows a quite large difference with values, respectively, around 0.083 and 0.057 when the current applied along the [11¯0] and [112¯] crystallographic directions of Pt(111) by the damping-like SOT efficiency using the harmonic Hall voltage measurement technique. The critical switching current densities also show large difference between these two orthogonal crystallographic orientations with the trend of that the larger SOT efficiency leads to the smaller critical switching current density. It independently confirms the generation of different damping-like SOT efficiency when current along [11¯0] and [112¯] directions of Pt(111). Moreover, a perpendicularly magnetized Pt/Co/Ta reference heterostructures with Pt having polycrystalline phase shows tiny variation of damping-like SOT efficiency in in-plane two orthogonal directions, which also indirectly indicates the crystallographic orientations related θSH in epitaxial Pt(111) layers. This study indicates that the θSH of epitaxial Pt is a crystallographic orientations related parameter.

Synthesis and comprehensive study of polyvinylidene fluoride–nickel oxide–barium titanate (PVDF–NiO–BaTiO3) hybrid nanocomposite films for enhancement of the electroactive beta phase

This study includes the successful fabrication of polyvinylidene fluoride (PVDF) based hybrid nanocomposite films loaded with nickel oxide (NiO) and barium titanate (BaTiO3) fillers via simple sol–gel casting techniques to optimize the crystallinity and β-phase formation for various sensor applications. A systematic study has been performed to assess the effect of fillers (NiO and BaTiO3) on the crystal structure, morphology and electrical conduction properties of PVDF–NiO–BaTiO3 hybrid nanocomposite films using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) using energy dispersive spectroscopy and current–voltage (I–V) measurement techniques. XRD and FTIR results indicate that the incorporation of nanostructured fillers NiO and BaTiO3 leads to the formation of long stabilized planar zigzag and all-trans conformation (TTTT) inducing the growth of electroactive β-phase and crystallinity. XRD results show that the degree of crystallinity reaches a maximum value of 85% for incorporation of 2.5 wt% of NiO and 27.5 wt% of BaTiO3. FTIR results show 85% of electroactive β-phase growth achieved by incorporating 7.5 wt% of NiO and 22.5 wt% of BaTiO3. FESEM micrographs of hybrid films show that both NiO and BaTiO3 particles are well dispersed within the PVDF pattern with the porous surface resulting in enhanced electrical conductivity. Current–voltage (I–V) measurement shows the charge transport process in PVDF composites loaded with NiO and BaTiO3 fillers is mainly governed by Richardson Schottky emission. The significant increase in the electrical conductivity of PVDF–NiO–BaTiO3 hybrid nanocomposite opens a new window for possible use in miniaturization of electronics and energy harvesting devices.

Investigation of optical and electrical properties of erbium-doped TiO2 thin films for photodetector applications

We have investigated the electrical and optical properties of erbium (Er3+) doped TiO2 thin films (Er:TiO2 TFs) grown by sol–gel technique on glass and silicon substrates. The samples were characterized by field emission gun–scanning electron microscopes (FEG–SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), X-ray diffraction (XRD), photoluminescence (PL) and current–voltage measurement techniques. FEG–SEM and AFM images showed the morphological change in the structure of Er:TiO2 TFs and EDX analysis confirmed the Er3+ doped into TiO2 lattice. Broad PL emissions in visible and infrared regions were observed in undoped TiO2 samples and associated to different mechanisms due to the anatase and rutile phases. PL spectra revealed sharp peaks at 525 nm, 565 nm, 667 nm and 1.54 µm which are related to Er3+ emissions in Er:TiO2 samples. The undoped TiO2 and Er:TiO2 TFs based UV-photodetectors were fabricated, and various device parameters were investigated. The doped devices exhibit high photoresponse upon illuminating 350 nm UV light at 2 V bias with faster response time compared to undoped device.

Noncontact AC Voltage Measurements: Error and Noise Analysis

A capacitive noncontact ac voltage measurement technique and its feasibility to measure arbitrary waveform signals are analyzed. The method provides self-calibration of the scale factor, an important feature considering the high variability that coupling capacitances present. The analysis of several errors related to the technique is performed, showing the impact of different design parameters on the final accuracy. Scaling errors due to the electronic circuit can be constrained to less than 0.5%, and can be disaffected, whereas those due to the frequency dependence of cable sheath permittivity can be up to 3% for polyvinyl chloride sheathed cables. This error is not controllable by electronic design but requires working on electrode probe. A noise model is also proposed and experimentally validated, showing that signal-to-noise ratios of up to 100 dB are achievable with common components. A functional prototype was built and tested by acquiring power-line voltage and other arbitrary signals without contact. Instantaneous voltage signals were acquired by the proposed technique and contrasted with those acquired directly. For the measurement of power-line voltage and using the self-calibration feature, the instantaneous error was lower than 7 V (2.2%) for a ±1300 V measurement range at 50 Hz. If manual correction is applied, the error can be reduced to 0.28 $\text{V}_{\text {rms}}$ (0.12%).

A Fast $V_{th}$ Measurement (FVM) Technique for NBTI Behavior Characterization

In this letter, a novel fast threshold voltage ( ${V}_{th}$ ) measurement (FVM) technique is proposed and demonstrated, which could perform ${I}$ – ${V}$ characterization of MOSFETs within 1 ns. With the advanced FVM technique, down to 1-ns negative biased temperature instability (NBTI) characterization was successfully carried out for Si pFinFETs at 14-nm technology node. It is experimentally confirmed that the nano-second-level fast recoverable traps, which are generated during NBTI stress, could lead to the underestimation of ${V}_{th}$ degradation under micro-second-level measurement speed. Furthermore, it is found that even when the ${V}_{th}$ measurement is performed within 1 ns after the stress removal, it is still not fast enough to be the real recovery-free measurement. Yet, with the proposed FVM technique, NBTI characteristics could be characterized more accurately and closer to its intrinsic behaviors.

Characterizing Angular Dependence of Spin-Orbit Torque Effective Fields in Pt/(Co/Ni)2/Co/IrMn Structure

We investigate the interplay between the spin-orbit torque (SOT)-induced effective fields and the azimuth angle of the magnetization vector with respect to the applied current. A method to quantify the ratio of the planar Hall effect to the anomalous Hall effect in perpendicular magnetic anisotropy (PMA) structures by using the low field harmonic Hall voltage measurement technique is devised. The validity of the ratio is confirmed by measuring the PMA effective field. In addition, a technique to characterize the SOT effective fields as a function of the magnetization vector azimuth angle with respect to the current direction is proposed and experimentally validated. The experimental results are in quantitative agreement with our derivations. Our measurement reveals that the field-like effective SOT fields are minima when the azimuth angle of magnetization with respect to the current is at 45°.

Analysis of High-Frequency Impedance Measurement Techniques for Power Line Network Sensing

A major aspect in power line distribution networks is the constant monitoring of the network properties. With the advent of the smart grid concept, distributed monitoring has started complementing the information of the central stations. In this context, power line communications modems deployed throughout the network provide a tool to monitor high frequency components of the signals traveling through a power line network. We propose therefore to use them not only as communication devices but also as network sensors. Besides classical voltage measurements, these sensors can be designed to monitor high frequency impedances, which provide useful information about the power line network, as for instance status of the topology, cable degradation and occurrence of faults. In this article, we provide a technical analysis of different voltage and impedance measurement techniques that can be integrated into power line modems. We assess the accuracy of the techniques under analysis in the presence of network noise and we discuss the statistical characteristics of the measurement noise. We finally compare the performances of the examined techniques when applied to the fault detection problem in distribution networks, in order to establish which technique gives more accurate results.

Power frequency AC voltage measurement based on double wound Rogowski coil

This study presents a technique for power frequency AC voltage measurement. The proposed technique utilises a capacitor having a low capacitance in addition to a double wound Rogowski coil. This technique depends on capacitor current measurement using the double wound Rogowski coil. The voltage across the capacitor that connected in parallel with the system at which AC voltage is intended to be measured is reconstructed. The proposed technique is experimentally evaluated by designing the measurement system and using a digital signal processing board for the reconstruction processes. Moreover, the experimental results based on Rogowski coil measurements are compared with those obtained from reference techniques. Finally, the obtained results validate the efficacy of the proposed technique in power frequency AC voltage measurement.

Non‐intrusive voltage measurement of ac power lines for smart grid system based on electric field energy harvesting

A new non-intrusive ac voltage measurement technique based on stray electric filed energy harvesting is presented whereby the voltage of ac power lines can be measured without removing insulation and therefore without direct contact with conductors of the power lines. The energy of electric field around the power lines is picked up and stored in a capacitor by a wire wound around insulated 3-wire household power lines or by a conductor plate placed in the vicinity of overhead high-voltage power lines. Autonomous switches are used to monitor the stored electric field energy in a storage capacitor and to generate pulse train. Experimental results show that the repetition rate of the output pulse is a linear function of the line voltage. Since the voltage of insulated 3-wire household power line can be measured without removing insulation and the voltage of high-voltage power transmission line can be measured without any contact to the conductor of the power line, the proposed technique can be widely applied to smart grid system.

Improvement of band gap profile in Cu(InGa)Se2 solar cells through rapid thermal annealing

In the paper, the effect of rapid thermal annealing on non-optimal double-graded band gap profiles was investigated by using X-ray photoelectron spectroscopy and capacitance–voltage measurement techniques. Experimental results revealed that proper rapid thermal annealing treatment can effectively improve band gap profile to more optimal level. The annealing treatment could not only reduce the values of front band gap and minimum band gap, but also shift the position of the minimum band gap toward front electrode and enter into space charge region. In addition, the thickness of Cu(InGa)Se2 thin film decreased by 25nm after rapid thermal annealing treatment. All of these modifications were attributed to the inter-diffusion of atoms during thermal treatment process. Simultaneously, the variation of the band gap profile created an absolute gain in the efficiency by 1.22%, short-circuit current density by 2.16mA/cm2 and filled factor by 3.57%.

Wideband optical phase modulator half-wave voltage measurement technique based on phase modulation optical link

We measured the half-wave voltage Vπ of LiNbO3 phase modulators in the broadband frequency range by analyzing the gain of phase modulation interference demodulation optical link. This is a new high practical value measurement method for half-wave voltage of LiNbO3 phase modulators in wideband frequency range, and can accurately predict the nonlinear frequency characteristics of phase modulation optical link.