Current Hysteresis Research Articles

Influence of high temperature degaussing on lifting capacity of linear motor reciprocating pump

The submersible linear motor reciprocating pump is a new type of artificial lift. The degaussing effect of its permanent magnet at high temperature will reduce the lifting capacity of the linear motor reciprocating pump. In this paper, the thermal stability of NdFeB permanent magnet material was studied by simulating the underground temperature and pressure conditions in a high-temperature and high-pressure reactor and combining with a Tesla instrument. The results show that NdFeB material loses its magnetism rapidly at high temperature, and the residual magnetism is proportional to the ambient temperature of the magnet. The high temperature demagnetization effect of large magnets is more serious due to eddy current loss and hysteresis loss.

Electrical Characterization and Study of Current Drift Phenomena and Hysteresis Mechanism in Junctionless Ion-Sensitive Field-Effect Transistor

A comprehensive study of the drain current drift mechanism and hysteresis phenomena in fabricated p-channel junctionless ion-sensitive field-effect transistor (JL-ISFET) has been investigated for the first time. The current drift measurements have been performed through transient analysis of drain current, under different pH and liquid-gate bias (Vlg). Further, time-dependent gate-capacitance (CG) has also been analyzed to see the effect of hydroxyl ions (OH−) in the sensing film (Al2O3). The hysteresis has also been investigated for different pH loop (7 → 3 → 7 → 11 → 7 and 7 → 11 → 7 → 3 → 7) and times (960s, 1500s, and 1920s). It has been observed that the drift of JL-ISFET occurs because of chemical modification of the sensing film, due to OH−. The proposed device exhibits a threshold voltage sensitivity of 58.2 mV/pH that is near the Nernstian limit. Further, the hysteresis width and maximum drain current drift are measured as \(\sim \) 1.3 mV and 2.4 μ A (\(\sim \) 75%), respectively.

The current hysteresis effect of tower-like MoS2 nanocrystalline film for field emission and memristor applications

In this work, we investigate the hysteresis effect of the current-voltage characteristic for the magnetron sputtered molybdenum disulfide (MoS2) nanocrystalline films. The field emission hysteresis of MoS2 cold cathode is studied by sweeping mode with voltage upward/downward, the vacuum pressure has a remarkable effect on the hysteresis of the emission current and overall the hysteresis becomes more prominent as pressure rises. Besides, we also demonstrate the current-voltage behaviors of MoS2 film using thermal evaporated Al dot as top electrode and copper foil substrate as bottom electrode. The Al/MoS2/Cu configuration device presents an obvious current hysteretic effect and the current increases with the increase of the voltage sweeping times. The possible mechanism of the hysteresis has been proposed herein and also investigations provide a great promise for the development of magnetron sputtered MoS2 nanocrystalline films in applications such as field emitters and memristor devices.

A simplified model of a current transformer for studying relay protection operation in transient conditions

We develop a simplified model of a current transformer based on its current-voltage characteristic. This model is applicable for studying relay protection operation in transient conditions when no high accuracy or consideration of current transformer magnet core hysteresis is required. The model was developed in MATLAB Simulink using elements of the SimPowerSystems and Simscape libraries. The model uses the transformation ratio and current-voltage characteristic obtained during operational tests of a current transformer. Calculation experiments with non-linear resistance found that a currentvoltage characteristic of voltage and current values can be used to model a current transformer, rather than instantaneous values. The following conditions were simulated: for nominal currents in current transformer windings to check the transformation ratio; for opened secondary winding; with current transformer saturation by increasing secondary loading; increasing the primary current ratio and presence of aperiodic current at the start of the transition process. It was found that the developed current transformer model allows for a correct imitation of all the above conditions. To verify the model, secondary current oscillograms were obtained using real current transformers 10 kV at known primary current, which were compared with nominal oscillograms in the model. The discrepancy between the results of calculational and real experiments was no more than 10% in amplitude values, with high-quality matching obtained for current charts in the model and real current transformers. A significant advantage of the developed model is that its setting requires no information on magnet core cross-section, power line length, steel grade, and the number of current transformer winding turns.

Performance and reliability in back-gated CVD-grown MoS2 devices

In this work, the electrical performance and reliability of as-synthesized CVD-grown MoS2 transistors directly grown on SiO2/Si substrate without any transfer process have been evaluated. Transfer and output characteristics, current hysteresis, capacitance-voltage and low-frequency noise signatures have been characterized revealing the huge influence of surface and oxide defects and the disturbance due to the fluctuations of the carrier number on the back-gated transistor response.

Minimization of torque ripple in switched reluctance motor based on MPC and TSF

In this paper, a novel control method based on model predictive control (MPC) and torque sharing function (TSF) is addressed to minimize the torque ripple of switched reluctance motor (SRM). Firstly, an accurate SRM model is established based on flux‐linkage characteristic curves obtained from the locked rotor test, which can predict the future operation state of the SRM drive system. Secondly, an improved TSF curve is proposed, and genetic algorithm is used to optimize TSF parameters to reduce torque ripple in commutation region. Besides, the MPC is integrated into the TSF control framework to replace the traditional hysteresis controller, and establishes a new TSF‐based model predicted torque control (MPTC) method, which avoids the frequency conversion problem caused by torque or current hysteresis controller. Further, a sector division scheme is addressed to decrease the number of candidate voltage states, whereby the computation of the controller in each sampling period is effectively reduced. Finally, in order to verify the correctness of the MPTC method, it is compared with the traditional direct instantaneous torque control (DITC). Both simulations and experiments on a three‐phase 12/8 pole SRM have confirmed that MPTC scheme can not only decreases torque ripple and stator copper losses, but also has higher efficiency than DITC. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Crystal orientation dependence of deep level spectra in proton irradiated bulk β-Ga2O3

The effects of 20 MeV proton irradiation with fluences of 5 × 1014 and 1015 p/cm2 on electrical properties of lightly Sn doped n-type (net donor concentration 3 × 1017 cm−3) bulk β-Ga2O3 samples with (010) and (−201) orientation were studied. Proton irradiation decreases the net donor density with a removal rate close to 200 cm−1 for both orientations and similar to the electron removal rates in lightly Si doped β-Ga2O3 epilayers. The main deep electron traps introduced in the β-Ga2O3 crystals of both orientations are near Ec−0.45 eV, while in Si doped films, the dominant centers were the so-called E2* (Ec−0.75 eV) and E3 (Ec−0.1 eV) traps. Deep acceptor spectra in our bulk –Ga2O3(Sn) crystals were dominated by the well-known centers with an optical ionization energy of near 2.3 eV, often attributed to split Ga vacancies. These deep acceptors are present in a higher concentration and are introduced by protons at a higher rate for the (010) orientation. Another important difference between the two orientations is the introduction in the surface region (∼0.1 μm from the surface) of the (010) of a very high density of deep acceptors with a level near Ec−0.27 eV, not observed in high densities in the (−201) orientation or in Si doped epitaxial layers. The presence of these traps gives rise to a very pronounced hysteresis in the low temperature forward current–voltage characteristics of the (010) samples. These results are yet another indication of a significant impact of the orientation of the β-Ga2O3 crystals on their properties, in this case, after proton irradiation.

Suppressed light-induced phase transition of CsPbBr2I: Strategies, progress and applications in the photovoltaic field

The rapid rise in the power conversion efficiency (PCE) of CsPbBr2I-based perovskite solar cells (PSCs), from 4.7% in 2016 to 11.08% in 2020, render it a promising material for use in photovoltaic devices. However, the phase stability and current hysteresis caused by photo-induced phase segregation in CsPbBr2I represent major obstacles to further improvements in the PCE for such devices. In this review, we describe the basic structure and optical properties of CsPbBr2I, and systematically elaborate on the mechanism of the phase transition. We then discuss the strategies in progress to suppress phase transition in CsPbBr2I, and their potential application in the photovoltaic field. Finally, challenges and application prospects for CsPbBr2I PSCs are summarized in the final section of this article.

An Improving Hysteresis Current Control Method Based on FOC Technique for Induction Motor Drive

The paper presents an improving speed control method using a field-oriented control (FOC) technique for the hysteresis current (HC) controller in the induction motor drive. The basic principle of a controller applying hysteresis band current is comparing reference currents and the measured currents to generate switching pulses for controlling an inverter. In the typical FOC for the HC controller, the rotor flux angle’s value will increase to infinity due to the integral algorithm’s error accumulation. This problem can lead to the faulty operation of the induction motor drive (IMD) system. In this paper, a current model with the advantage of precisely determining the periodic rotor flux angle is used in the FOC technique to provide reference currents for the current controller. The rotor flux angle will periodically change according to the motor speed in the range [-π π] during the operation of IMD. The operation of the induction motor drive is implemented and tested by MATLAB/SIMULINK software. The simulation results have demonstrated the effectiveness of the HC control method-based FOC technique with periodic rotor flux angle in controlling motor speed. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

Ion sensitivity from current hysteresis in InAs nanowire field-effect transistors functionalized with ionophore-doped fluorosilicone membranes

Trapping of environmental charges in surface states typically dominates electrical transport in nanostructured field-effect transistors (FETs) applied as sensors. Such surface effects produce exceptional sensitivity, yet time dependencies on experimental timescales simultaneously results in hysteresis of FET conductance and signal instability. Whereas hysteresis is usually suppressed by means of chemical surface treatments, here we study it as a source of information for ion sensing. Ion-sensitive FETs were prepared by coupling InAs nanowires to fluorosilicone membranes doped with Na+ ionophores. From cyclic transfer characteristics in electrolytes of varying concentration, potentiometric and hysteretic calibration curves were obtained. The observed hysteresis was attributed to changes in membrane capacitance by redox reactions between ionized donor-like traps at the InAs surface and electroactive membrane constituents. Hysteresis was correlated to the ion potential through a model and demonstrated a filtering effect that stabilized the hysteretic response against potential drifts. Furthermore, the model elucidated the ability to modulate ion sensitivity by controlling the initial density of ionized traps via electrostatic polarization by the gate. In this mode of active operation, we demonstrate enhancement above the Nernstian limit with linear calibrations of (−77.5 ± 3.2 to −80.7 ± 3.0 mV/dec) despite the presence of non-equilibrium ion fluxes.

Synergistic Engineering of Conduction Band, Conductivity, and Interface of Bilayered Electron Transport Layers with Scalable TiO2 and SnO2 Nanoparticles for High-Efficiency Stable Perovskite Solar Cells

A simple, synergistic engineering of the conduction band (CB), conductivity, and interface of TiO2-based bilayered electron transport layers (ETLs) via scalable TiO2 and SnO2 nanoparticles processed at low temperature (≤ 100 °C) for regular planar perovskite solar cells (PSCs) was developed. The bottom layer (Lt-TiO2:SnO2 nanocomposite film) was prepared by spin coating from the ethanol suspension of small ground TiO2 nanoparticles with big ground SnO2 nanoparticles as the additive. The top C-SnO2 layer (spin-coated from the concentrated commercial SnO2 nanoparticles (C-SnO2 NPs, 20 wt %, 7 nm in size suspended in H2O)) can be regarded as an interlayer between Lt-TiO2:SnO2 and perovskite (Psk) absorbers. Bilayered Lt-TiO2:SnO2/C-SnO2 ETLs are dense films with a cascade CB, good conductivity, facile electron extraction/transport ability, and a highly hydrophilic surface for depositing high-quality Psk films. Regular planar PSCs based on Lt-TiO2:SnO2/C-SnO2 ETLs combined with a (FAI)0.90(PbI2)0.94(MABr)0.10(PbBr2)0.10 absorber and a spiro-OMeTAD hole transporter achieved the highest power conversion efficiency of 22.04% with a negligible current hysteresis. The champion cell lost less than 3% of the initial efficiency under continuous room lighting (1000 lux) for 1000 h (lost 10% after 2184 h) without encapsulation under an inert atmosphere. Four related low-temperature-processed ETLs (Lt-TiO2/C-SnO2, Lt-C-SnO2, Lt-TiO2:SnO2, and Lt-TiO2) were fabricated using the same metal oxide nanoparticle suspensions and studied simultaneously to reveal the function of each metal oxide in the bilayered Lt-TiO2:SnO2/C-SnO2 ETLs. In the bottom Lt-TiO2:SnO2 layer, small TiO2 nanoparticles were needed for making a dense film, and highly conducting big SnO2 nanoparticles are used to increase the conductivity of ETLs and a handy electron transport path for reducing the charge accumulation and series resistance of the cell. A top C-SnO2 layer (regarded as an interlayer between Psk and Lt-TiO2:SnO2) was used to extract/transport electrons facilely, to form a bilayered ETL with a cascade CB, and to create a hydrophilic surface to deposit high-quality Psk films to enhance the photovoltaic performance of the PSCs. This study provides a blueprint for designing good-performance ETLs for high-efficiency, stable regular planar PSCs using various sized nanoparticles prepared in a very simple and low-cost way.

Thermoelectrical Characterization of Piezoelectric Diaphragms: Towards a Better Understanding of Ferroelectrics for Future Memory Applications

This work deals with the thermoelectric characterization of commercial lead zirconate titanate (PZT) based piezoelectric diaphragms. An in-depth analysis of the piezo- and ferroelectric behavior of the samples was carried out by measuring current voltage curves and polarization hysteresis cycles in a wide temperature range. We demonstrate that, as the temperature decreases, higher electric fields are needed to completely polarize the sample. Furthermore, I-V measurements, polarization hysteresis loops and coercive fields allow us to confirm that the samples present different grain sizes. From impedance measurements, resonance frequency values, capacitance and permittivity were determined at temperatures ranging from 100 to 320 K. It is shown that impedance maxima shift towards greater frequency values when decreasing the temperature, which is mainly attributed to the appearance of an internal stress that generates larger stiffness in the ceramic. Finally, an electroacoustic characterization was made by measuring the sound pressure of the diaphragms in the human hearing frequency range.

Low-pressure treatment of CuSCN hole transport layers for enhanced carbon-based perovskite solar cells

Low-cost and stable carbon-based hole-conductor layers have attained especial interest in perovskite solar cells (PSCs). Because the carbon-based hole-conductor-free PSCs usually have the serious problems of low power conversion efficiency (PCE) and obvious current hysteresis. Herein, we introduced CuSCN hole transfer layers (HTLs) with low pressure treatment (LPT) into carbon-based PSCs to improve the performance and reduce the hysteresis. After being coated, the CuSCN layers were immediately transferred to low-pressure environment for vaporizing the polar diethyl sulfide (DES) without destruction of perovskite films. Our champion device engineered through carbon-based PSCs with low-pressure-treated CuSCN HTLs achieved power conversion efficiency (PCE) of 13.05%, compared with 10.6% of that without CuSCN layer. Importantly, the incorporating CuSCN HTLs can build energy level cascade to obviously reduce the current hysteresis due to the balanced electrode-hole extraction ability. Moreover, the stability of the device was obviously improved due to the hydrophobic nature of CuSCN layer. While the low-temperature (~20 °C and 50 °C) volatilizing DES in CuSCN layer destroyed the perovskite films under room pressure, which reduced the PCE to 8.6% and 9.9%, respectively. Thereby, this work highlights the advantages of incorporating low-pressure-treated CuSCN HTLs into carbon-based PSCs with improving performance and reducing current hysteresis, which will promote the future industrial application.

Vector Control of Induction Motor Using Neural Networks Based Lookup Table for Reduced CMV

This paper confers a vector control (VC) perspective for induction motor drives by combining the principles of vector and direct torque control (DTC) methods. In classical vector control, the switching states will be chosen dependent on current hysteresis regulators. Based on the instantaneous current waves, the hysteresis controllers generate the switching specimen. But, the classical DTC selects the pertinent voltage vector from lookup table extracted from the flux and torque error signals and sector information. The proposed perspective combines both VC and DTC techniques. In this paper d and q-axis current errors and sector information, the lookup table chooses an appropriate voltage vector. Moreover, to select the befitting voltage vector Neural Network (NN) based approach is presented in this paper. Also, to reduce the common mode voltage (CMV) variations, NN based lookup tables are proposed. To substantiate the proposed NN based vector control, simulation studies have been conveyed and results are collated.

Hysteresis loss calculations of 2D and 3D large-scale HTS coil models: from multi-scale method to multi-dimension method

Here we propose a new approach capable of calculating the hysteresis loss of 3D HTS coil models based on the modeling framework of the multi-scale method. The study enhances the multi-scale method for 2D simulations by introducing the homogenization technique to simplify the topological features of coils’ cross sections. With the simplification, a 3D A-formulation magnetostatic model is built for magnetic field estimation, while a 2D H-formulation superconducting model is solved for the tape’s current density and hysteresis loss. Since different spatial dimensions are employed in the submodels, we refer to it as the multi-dimension method. We demonstrate the data transferring between the 2D or 3D homogenized coil submodel and the 2D single-tape submodel. The benchmark results show that hysteresis losses from the developed models and reference models are in good agreement, with errors of less than 1% and 6% in simulating the target 2D solenoid coil and 3D racetrack coil, respectively. The distributions of current density and magnetic field in both models are highly consistent. Meanwhile, the developed models speed up the calculations by one to five times compared with the reference models. Due to the easy calculation of 3D magnetostatic models and 2D superconducting models, the multi-dimension method may pave a new way to 3D electromagnetic simulations for larger-scale and more complex high temperature superconducting conductors and coils.

Suppression of hysteresis in all-inorganic perovskite solar cells by the incorporation of PCBM

All-inorganic halide perovskites (AIHPs) have become one of the most promising materials for commercial perovskite photovoltaics owing to their enhanced efficiency and thermodynamic stability. Output instability, such as current hysteresis, is stressed in organic-inorganic hybrid perovskite photovoltaics but is neglected in AIHP solar cells. Here, the origin and suppression of current hysteresis in AIHP solar cells are addressed from a microscopic viewpoint. The incorporation of fullerene into AIHP films efficiently suppresses ion migration, which alleviates the macroscopic current hysteresis in solar cells. This result is confirmed by both Kelvin probe force microscopy and conductive atomic force microscopy measurements. Our results provide an advanced understanding of the microscopic properties of AIHPs but also clearly clarify how to suppress the macroscopic current hysteresis, which further inspires the optimization of solar cells up to the levels of organic–inorganic hybrid counterparts.

Work function engineering to enhance open-circuit voltage in planar perovskite solar cells by g-C3N4 nanosheets

Enhancement of open-circuit voltage (Voc) is an effective way to improve power conversion efficiency (PCE) of the perovskite solar cells (PSCs). Theoretically, work function engineering of TiO2 electron transport layer can reduce both the loss of Voc and current hysteresis in PSCs. In this work, two-dimensional g-C3N4 nanosheets were adopted to modify the compact TiO2 layers in planar PSCs, which can finely tune the work function (WF) and further improve the energy level alignment at the interface to enhance the Voc and diminish the hysteresis. Meanwhile, the quality of perovskite films and charge transfer of the devices were improved by g-C3N4 nanosheets. Therefore, the PCE of the planar PSCs was champed to 19.55% without obvious hysteresis compared with the initial 15.81%, mainly owing to the remarkable improvement of VOC from 1.01 to 1.11 V. In addition, the stability of the devices was obviously improved. The results demonstrate an effective strategy of WF engineering to enhance Voc and diminish hysteresis phenomenon for improving the performance of PSCs.

Current mode control of single phase grid tie inverter with anti-islanding

The aim of this paper is to explore the use of various current mode control (CMC) techniques to design a single phase grid tie inverter integrated with anti-islanding protection. Three types of CMC techniques have been discussed, namely current hysteresis control (CHC), constant frequency control (CFC) and average current mode control (ACMC). The performance of the grid tie inverter in the event of grid voltage failure is also studied to help install an anti-islanding mechanism. The proposed control techniques shall eliminate the use of Phase locked loop (PLL) control as the current reference is generated from the grid voltage itself. All three current mode control techniques of an inverter have been simulated in MATLAB/Simulink to evaluate the performance of the designed inverter. The simulated results show a current THD of less than 5% in all three methods and a good anti-islanding response.

Tuning the dynamics of magnetic droplet solitons using dipolar interactions

Magnetic droplets are dissipative magnetodynamical solitons that can form under current driven nanocontacts in magnetic layers with large perpendicular magnetic anisotropy. Here, we extend the original droplet theory by studying the impact of the dipolar interactions on the dynamics of droplet solitons. By varying the thickness of the free layer of a spin torque nano-oscillator, we systematically tune the internal field of the free layer to investigate the dynamics of droplet solitons. Our numerical results show that increasing the free layer thickness increases the droplet threshold current, decreases the droplet frequency and diameter, enlarges the current hysteresis and also modifies the structure of the droplet. The Oersted field of the current breaks the phase coherency and deteriorates the stability of the droplet in free layers with larger thicknesses. Moreover, our findings show a simple relation to determine the impact of the free layer thickness on the droplet nucleation boundaries. Our study presents the missing brick on the physics behind magnetic droplet solitons, and further illustrates that magnetic droplets in thinner layers possess more promising characteristics for spintronic applications and enable devices with higher speed of operation.

Diode-Like Current Leakage and Ferroelectric Switching in Silicon SIS Structures with Hafnia-Alumina Nanolaminates.

Silicon semiconductor-insulator-semiconductor (SIS) structures with high-k dielectrics are a promising new material for photonic and CMOS integrations. The “diode-like” currents through the symmetric atomic layer deposited (ALD) HfO2/Al2O3/HfO2… nanolayers with a highest rectification coefficient 103 are observed and explained by the asymmetry of the upper and lower heterointerfaces formed by bonding and ALD processes. As a result, different spatial charge regions (SCRs) are formed on both insulator sides. The lowest leakages are observed through the stacks, with total Al2O3 thickness values of 8–10 nm, which also provide a diffusive barrier for hydrogen. The dominant mechanism of electron transport through the built-in insulator at the weak field E < 1 MV/cm is thermionic emission. The Poole-Frenkel (PF) mechanism of emission from traps dominates at larger E values. The charge carriers mobility 100–120 cm2/(V s) and interface states (IFS) density 1.2 × 1011 cm−2 are obtained for the n-p SIS structures with insulator HfO2:Al2O3 (10:1) after rapid thermal annealing (RTA) at 800 °C. The drain current hysteresis of pseudo-metal-oxide-semiconductor field effect transistor (MOSFET) with the memory window 1.2–1.3 V at the gate voltage |Vg| < ±2.5 V is maintained in the RTA treatment at T = 800–900 °C for these transistors.