Voltage Signal Research Articles

Current Mirror Improved Potentiostat (CMIPot) for a Three Electrode Electrochemical Cell.

This work presents a novel compact CMOS potentiostat-designed circuit for an electrochemical cell. The proposed topology functions as a circuit interface, controlling the polarization of voltage signals at the sensor electrodes and facilitating current measurement during the oxidation-reduction process of an analyzed solution. The potentiostat, designed for CMOS technology, comprises a two-stage amplifier, two current mirror blocks coupled to this amplifier, and a CMOS push-pull output stage. The electrochemical method of cyclic voltammetry is employed, operating within a voltage range of ±0.8 V and scan rates of 10 mV/s, 25 mV/s, 100 mV/s, and 250 mV/s. The circuit is capable of reading currents ranging from 10 µA to 500 µA. Experimental results were obtained using a potassium ferrocyanide K3[Fe(CN)6] redox solution with concentrations of 10, 15, and 20 mmol/L, and their corresponding voltammograms were evaluated. The experimental results from a discrete circuit demonstrate that the proposed potentiostat topology produces outcomes consistent with those of classical topologies presented in the literature and industrial equipment.

A Fault Diagnosis Method for Electric Vehicle Lithium Power Batteries Based on Dual Feature Extraction from the Time and Frequency Domains

Abstract This study focuses on the safety and reliability issues of lithium-ion batteries, proposing a fault diagnosis strategy that leverages dual feature extraction in the time-frequency domains. Additionally, by modifying the traditional autoencoder, the study proposes a feature-guided autoencoder as an unsupervised model for extracting features in the time domain. Initially, wavelet packet decomposition and its energy denoising treatment are employed to refine fault information within battery voltage signals. Subsequently, the reconstruction error outputted by the Feature-Guided Autoencoder is utilized as the time-domain fault feature, while the cosine similarity of the energy of signals in various frequency bands obtained after wavelet packet decomposition serves as the frequency-domain fault feature. Ultimately, this paper selects the Isolation Forest algorithm for two-dimensional outlier detection of time-frequency features. Experimental results demonstrate that the Feature-Guided Autoencoder proposed in this study not only enhances the sensitivity of time-domain fault features compared to traditional autoencoders and their variants but also optimizes issues related to training time and computational load. The effectiveness of the proposed dual feature fault diagnosis method in both the time and frequency domains is validated through data from two actual vehicles, showing superior early fault detection capability relative to single-feature fault diagnosis methods.

Coronary sinus signal amplitude: A predictor of the atrial substrate and low voltage areas.

Low voltage areas (LVA) are pivotal in atrial fibrillation (AF) pathogenesis, influencing local left atrial LA excitation and perpetuating AF occurrences. While pulmonary vein isolation (PVI) with cryo-balloon (CB) ablation is effective for AF, it doesn't provide insights into the LA substrate or detect LVA, which affects ablation success rates. This study examines whether LA voltage and LVAs can be anticipated by analyzing the voltage signal amplitude at the coronary sinus (CS) catheter, which is standard in CB and radiofrequency ablation procedures. A retrospective analysis of 284 patients with recurrent AF undergoing RF catheter ablation was conducted at a high-volume EP center in Germany. The correlation between LA voltage and LVA with the CS signal was explored. The signal amplitude in the CS significantly correlated with voltage in LA walls, particularly in the proximal CS (correlation coefficient ρ=0.81, p<0.001). A CS signal cut-off of 1.155mV effectively predicted severe atrial LVAs (>40%) with a sensitivity of 90.7% and a specificity of 100%. While a threshold of 1.945mV identified patients with no significant atrial LVAs (<5%) with a sensitivity of 88% and a specificity of 50% (AUC: 0.81, 95% CI: 0.71-0.89, p<0.001). The CS signal amplitude is associated with the LA voltage. Due to its potential as a diagnostic tool for atrial LVAs, the signal amplitude in the CS could provide valuable information about the LA substrate, especially when 3D mapping is not feasible.

Harmonic voltage phasor reconstruction and harmonic state estimation based on the measurement data of a capacitive voltage transformer

AbstractHarmonic state estimation, which highly depends on accurate synchronised phasors, is a crucial basis for the location, traceability, and governance of harmonics in power systems. However, most existing synchronous phasor measurement units (PMUs) provide power frequency phasors rather than harmonic phasors. In addition, as the dominant voltage signal provider for PMUs in power systems, capacitive voltage transformers (CVTs) have complex frequency responses and cannot be directly used for harmonic measurement. Therefore, accurate harmonic state estimation is difficult to achieve in applications. A method for harmonic voltage phasor reconstruction and harmonic state estimation based on the measurement data of a CVT is proposed. First, the reasons for harmonic voltage measurement errors were analysed. Second, the scattering parameter method was used to measure the wideband voltage transfer characteristics of CVT. Third, a voltage reconstruction method was proposed to improve the measurement accuracy and expand the frequency range of synchronous phasor measurement. Fourth, this method was applied to harmonic state estimation, and the performance of harmonic state estimation before and after voltage reconstruction was quantitatively compared. Results showed that the proposed method can remarkably improve the accuracy of harmonic state estimation. Finally, some factors, such as state observability, complex error disturbances, CVT structure, and harmonic order, influencing the performance of the proposed method were investigated. Results further demonstrated that the method has high accuracy, strong anti‐interference, and adaptability, and can provide basic information for harmonic localisation and traceability.

Crack-Based Composite Flexible Sensor with Superhydrophobicity to Detect Strain and Vibration.

Vibration sensors are widely applied in the detection of faults and analysis of operational states in engineering machinery and equipment. However, commercial vibration sensors with a feature of high hardness hinder their usage in some practical applications where the measured objects have irregular surfaces that are difficult to install. Moreover, as the operating environments of machinery become increasingly complex, there is a growing demand for sensors capable of working in wet and humid conditions. Here, we present a flexible, superhydrophobic vibration sensor with parallel microcracks. The sensor is fabricated using a femtosecond laser direct writing ablation strategy to create the parallel cracks on a PDMS film, followed by spray-coating with a conductive ink composed of MWCNTs, CB, and PDMS. The results demonstrate that the developed flexible sensor exhibits a high-frequency response of up to 2000 Hz, a high acceleration response of up to 100 m/s2, a water contact angle as high as 159.61°, and a linearity of 0.9812 between the voltage signal and acceleration. The results indicate that the sensor can be employed for underwater vibration, sound recognition, and vibration monitoring in fields such as shield cutters, holding significant potential for mechanical equipment vibration monitoring and speech-based human-machine interaction.

Anomaly Detection for Power Quality Analysis Using Smart Metering Systems.

The problem of Power Quality analysis is becoming crucial to ensuring the proper functioning of complex systems and big plants. In this regard, it is essential to rapidly detect anomalies in voltage and current signals to ensure a prompt response and maximize the system's availability with the minimum maintenance cost. In this paper, anomaly detection algorithms based on machine learning, such as One Class Support Vector Machine (OCSVM), Isolation Forest (IF), and Angle-Based Outlier Detection (ABOD), are used as a first tool for rapid and effective clustering of the measured voltage and current signals directly on-line on the sensing unit. If the proposed anomaly detection algorithm detects an anomaly, further investigations using suitable classification algorithms are required. The main advantage of the proposed solution is the ability to rapidly and efficiently detect different types of anomalies with low computational complexity, allowing the implementation of the algorithm directly on the sensor node used for signal acquisition. A suitable experimental platform has been established to evaluate the advantages of the proposed method. All the different models were tested using a consistent set of hyperparameters and an output dataset generated from the principal component analysis technique. The best results achieved included models reaching 100% recall and a 92% F1 score.

SF6 Experimental Study on the Variation Characteristics of Closing Prebreakdown Duration during Contact Deterioration of Circuit Breakers

The contact morphology change caused by high-current ablation will seriously affect the electric field distribution in the interrupter chamber, which in turn affects the closing prebreakdown arc duration, indicating that the prebreakdown arc duration can be used as one of the indicators to measure the contact ablation state. A circuit breaker simulated ablation test platform was established, and the voltage and current signals, electromagnetic field signals, and vibration signals in the process of circuit breaker closing were measured, and the closing prebreakdown duration was calculated. The results show that under the same size of the ablation current, with the ablation of the contacts, the closing prebreakdown duration shows an overall trend of increasing and then decreasing, and the larger the ablation current is, the larger the change in the closing prebreakdown duration is. At the same time, simulation verification was carried out, and the results show that the electric field distortion on the surface of the static arc contact inside the arc extinguishing chamber is the largest, and the ablation of the contact will further increase the degree of distortion of the electric field inside the arc extinguishing chamber. As the degree of ablation increases, the prebreakdown moment of the circuit breaker closing is advanced, and the prebreakdown duration increases.

Near Stochiometric LiNbO3 Crystal: the Piezoelectric Features and the Shear Horizontal Guided Wave Transducer for Structural Health Monitoring up to 650 °C.

The application of shear horizontal (SH) guided wave transducers in high-temperature structural health monitoring (SHM) is a topic of significant interest across various industrial engineering sectors. In this study, we utilized the novelty piezoelectric crystal of near stoichiometric lithium niobate (NSLN), which exhibited a robust piezoelectric response (d15 = 77.6 pC/N@room temperature). Next, the pure thickness shear vibration mode d15' through size optimization was designed. It was demonstrated that the NSLN-based ultrasonic guided wave transducers utilizing the optimum d15' mode were proficient in transmitting and receiving pure fundamental SH wave (SH0 wave) along two orthogonal main directions (0° and 90°) over a wide frequency range (100-350 kHz), exhibiting strong response to the SH0 wave. Under the driving voltage of 100 V, the signal voltages of the NSLN-based transducer were found to be on the order of 200.3 and 11.8 mV at room temperature and high temperature of 650 °C, respectively. Moreover, the NSLN-based SH0 transducer showcased its better defect localization ability, and the signal-to-noise ratio (SNR) sensitivity of NSLN-based transducer was evaluated to be 16.1 dB at high temperature of 650 °C. To sum up, the ultrasonic wave transducer based on NSLN crystal demonstrated higher potential applications for in situ SHM under elevated temperatures.

Development of PIND system based on resonant sensors and research on material identification methods for redundant particles

Abstract Aiming at the problems of the existing particle impact noise detection (PIND) system, such as low detection accuracy, high rate of misjudgment and missed judgment, and the inability to judge the material of internal redundant particles in real time, a method for automatic detection and material identification of redundant particles based on neural network recognition is proposed, and an automatic detection system for redundant particles of sealed electronic devices is developed. The system is equipped with multi-channel piezoelectric resonant sensors, which convert the redundant particle impact noise signal into a voltage signal, and then transmit the signal to the host using a high-speed data acquisition system. The upper computer uses a short-term energy threshold detection method to extract signal pulses; Then, a variety of time and frequency domain features are extracted and combined with wavelet domain features; Finally, by training the multi output neural network prediction model, it can automatically judge whether there are redundant particles in the tested parts, and automatically give the material information of the redundant particles. Experiments show that the accuracy of the system for material recognition of redundant particles with a mass greater than 0.1 mg can reach 88.6%.

Tiny bubble triboelectric nanogenerator functionalized by liquid film rupture

As an important energy carrier, bubble commonly exists in undersea and liquid-gas two-phase systems. Efficiently utilizing the bubble energy is critical for potential applications in energy harvesting and sensing in two-phase environment. However, the micro liquid layer inhibits the complete contact and restricts the performance. Herein, we proposed strategies for tiny bubble triboelectric nanogenerator (TB-TENG) featuring liquid film rupture to eliminate the screen between bubble and dielectric layer. We carried out optimization design by invasively rupturing the liquid film, achieving stable open-circuit voltage peak and transferred charge of 8.3 V and 3 nC by a 110-μL bubble, with a high peak power density yielding the existing tube-based studies. Additionally, for noninvasive and spontaneous liquid film rupture, a scalable bubble regulator was fabricated, which integrated the irregularly dispersed bubbly flow into slug flow. We demonstrated the self-powered undersea gas leakage detection system combining the TB-TENG with the bubble regulator. Assisted with the good bubble regulation adaptability, the total leakage gas volume and rate were measured based on the voltage signal, with a varied leakage rate of 0.72–6 mL/min. The strategy provides insights for the related research in liquid-gas two-phase systems in nature and industry.

A novel method for investigating the underwater explosion loads and bubble evolution

This paper presents an innovative experimental method for studying the evolution and energy output characteristics of underwater explosion bubbles. We independently constructed an experimental testing system for underwater electrical wire explosions (UEWE), in which electrodes connected to a metal wire serve as the load, and underwater explosions are initiated through instantaneous high-voltage discharge. By varying the diameter of the metal wire and configuring parallel wire arrays, we analyzed and discussed the explosion characteristic parameters and the current–voltage (I–V) signals under different conditions. The maximum bubble radius of the underwater metal wire explosion was compared with the corresponding equivalent explosive simulation results, and a numerical model for underwater metal wire explosion equivalent to explosive detonation was established. Subsequently, we discussed the characteristics of bubble generation and evolution under various conditions, clarifying the similarities and differences between wire explosions and explosive detonations. On this basis, we explored the propagation laws of shock waves and secondary pulsation waves (SPW) under different conditions. We also calculated and analyzed energy output characteristic parameters, such as shock wave energy and bubble energy. The results indicate that there are significant differences between copper wire and aluminum wire loads in UEWE. For copper wires with a diameter greater than 0.4 mm, the shock wave overpressure peak value significantly decreases, while for aluminum wires with a diameter greater than 0.5 mm, it slightly decreases. Both metals exhibit similar trends in parallel wire arrays, with the shock wave overpressure peak value initially increasing and then decreasing as the number of wires increases. Unlike underwater explosive detonations, the SPW peak value in UEWE may exceed that of the shock wave. For single wires, the SPW peak value of copper wires is generally higher than that of aluminum wires, but in wire arrays, the trend is reversed. The multi-wire parallel connection can improve the energy conversion efficiency of the shock waves. However, for bubble energy, under all conditions, a single aluminum wire with a diameter of 0.5 mm produced the maximum bubble energy, reaching 1023.1 J. These findings provide new insights into the energy features of UEWE.

Research on single-phase grounding fault location technology in distribution networks based on impedance method

This article mainly introduces the impedance based single-phase grounding fault location method for distribution networks, including its theoretical basis, algorithm steps, and simulation verification. First, starting from the impedance analysis of the transmission line model, the method of accurately measuring the location of the fault point through phase domain analysis is explained. Next, the process of impedance analysis for single-phase grounding faults was described in detail, that is, how to solve the impedance of the grounding fault points by calculating the voltage and current signals. Then, the specific process of the impedance based grounding fault location algorithm was introduced, including the calculation of equivalent load impedance, the calculation of starting voltage and current, the calculation of grounding current, and the solution of fault point location. Finally, simulation verification was conducted using an IEEE 34 node distribution system example in a MATLAB/Simulink environment, and the results showed that the algorithm has high positioning accuracy, with a maximum error of within 3%.

A Universal Biocompatible and Multifunctional Solid Electrolyte in p-Type and n-Type Organic Electrochemical Transistors for Complementary Circuits and Bioelectronic Interfaces.

The development of soft and flexible devices for collection of bioelectrical signals is gaining momentum for wearable and implantable applications. Among these devices, organic electrochemical transistors (OECTs) stand out due to their low operating voltage and large signal amplification capable of transducing weak biological signals. While liquid electrolytes have demonstrated efficacy in OECTs, they limit its operating temperature and pose challenges for electronic packaging due to potential leakage. Conversely, solid electrolytes offer advantages such as mechanical flexibility, robustness against environmental factors, and ability to bridge the interface between rigid dry electronics systems and soft wet biological tissues. However, few systems have demonstrated generality and compatibility with a wide range of state-of-the-art organic mixed ionic-electronic conductors (OMIECs). This paper introduces a highly stretchable, flexible, biocompatible, self-healable gelatin-based solid-state electrolyte, compatible with both p- and n-type OMIEC channels while maintaining high performance and excellent stability. Furthermore, this nonvolatile electrolyte is stable up to 120°C and exhibits high ionic conductivity even in dry environment. Additionally, an OECT-based complementary inverter with a record-high normalized-gain of 228 V-1 and a corresponding ultralow static power consumption of 1 nW is demonstrated. These advancements pave the way for versatile applications ranging from bioelectronics to power-efficient implants.

An Improved High-Frequency Voltage Signal Injection-Based Sensorless Control of IPMSM Drives With Current Observer

An Improved High-Frequency Voltage Signal Injection-Based Sensorless Control of IPMSM Drives With Current Observer

Polarized APSK modulation system with polymorphic SC signals

AbstractThis paper discusses a new symbol modulation scheme known as polarized amplitude and phase shift keying, (‐APSK) modulation with four rings in its basic form. The new scheme maps power‐polarized symbol pairs on its constellation in order to increase the number of data symbols. ‐APSK exploits a symbol mapper based on a conjugate power splitting algorithm. Product modulation is applied, where a voltage signal of a specified amplitude and phase is multiplied by another current signal of a specified amplitude and phase, thus forming polymorphic signals in the product constellation. At the receiver, an isolated detection is performed, where the voltage signal is detected independently of the received current signal. A selection combining scheme is then used. The results depict unity peak‐to‐average power ratio and low average symbol energy, which is desirable for Green communications in 5G networks. It presents lower bit error rates when compared with the state‐of‐the art ‐ary quadrature amplitude modulation, with a signal‐to‐noise ratio gap of at least . The proposed analytical framework closely matches the simulations for bit error rates under .

A high-fidelity lithium-ion battery emulator for electric vehicle application

Lithium-ion (Li-ion) battery has played a key role for the development of electric vehicle (EV) at present, while the Li-ion batteries in the market come from different manufactures. Verifying the performance of the battery management system (BMS) for various battery chemistries is a complex undertaking. This paper proposes a high-fidelity Li-ion battery emulator for EV applications. The emulator utilizes a battery model parameterized by a series of performance tests and a special-designed hardware platform. A three-order battery equivalent circuit model (ECM) is selected to provide the voltage and current reference signal in the processor. Subsequently, the hardware generates the high voltage and current signal in accordance with the reference. To ensure the high accuracy of the battery ECM, a 37 Ah nickel manganese cobalt (NMC) battery was selected for testing under both charge and discharge conditions, as well as across a temperature range of − 30℃ to 45℃. The battery emulator is verified on charge and discharge mode for both accuracy and dynamic performance validations.

High sensitivity flexible piezoelectric nanogenerator based on multi‐layer piezoelectric composite fiber for human motion energy harvesting

AbstractIn this study, a piezoelectric nanogenerator (PENG) based on multilayer composite fiber had good and stable piezoelectric output performance, which could realize biomechanical energy collection and human movement monitoring. The polyvinylidene fluoride‐hexafluoryl propylene (P(VDF‐HFP)) composite fiber doped with MXene was used as a promising piezoelectric functional layer (MPFP). By electrospinning, P(VDF‐HFP) composite fiber was constructed by alternating electrospinning with polyurethane (TPU) nanofibers layer by layer. The adoption of MXene as a functional filler promoted the transformation of P(VDF‐HFP) from α to piezoelectric β‐crystal, the piezoelectric β‐crystal content of P(VDF‐HFP) increased, and the dielectric properties and polarization levels were enhanced. At the same time, the multi‐layer structure design improved the piezoelectric sensitivity and mechanical properties of the composite fiber, and the composite fiber was more flexible and had longer tensile strain. With excellent dielectric and mechanical properties, 3MPFP/TPU/3MPFP/TPU multilayer composite fibers showed piezoelectric sensitivity of 10.88 V/kPa. Under the action of palm pressing, the PENG generated an open circuit voltage of 25 V, and the voltage signal of the device under different motion forms had specific characteristics such as peak value, frequency, and shape, which could be used to realize the analysis of human motion forms. This study provided an efficient, simple, and creative new idea for the application of flexible energy storage electronic devices, PENGs, and piezoelectric sensors.

Uniformity optimization of galvanometric illumination

Dual-axis galvanometer is used as a common beam steering component in diverse illumination and imaging approaches. In this paper, we propose an uncorrelated uniform illumination approach based on dual-axis galvanometric scanning. Specially, we analyze the mechanism of galvanometric illumination and elucidate three main factors affecting its uniformity properties. In this illumination module, the laser beam is deflected rapidly by the galvanometer which is driven by triangular voltage signals, and then focused by an f-θ lens to illuminate the object at an equal lateral scanning velocity. This method has lower coherent noise than extended laser illumination, higher brightness than partial coherent illumination and higher uniformity than galvanometric Lissajous trajectory driven by sinusoidal signals.

Evaluation of sensor-enabled piezoelectric geoelectric cable in cyclic shear tests of subgrade soil under vertical cyclic loads

Of late, deformation of subgrade soil has led to an increasing number of road subsidence diseases. Real-time monitoring of subgrade deformation is critical to ensure the safety of subgrade operations. In this paper, a sensor-enabled piezoelectric geoelectric cable (SPGC) with impedance strain effect and piezoelectric effect is tested. The SPGC impedance and voltage signals obtained by cyclic shear test under vertical static load and cyclic shear test under vertical cyclic load are used to evaluate the monitoring effect. The results showed that normal stress had the greatest effect on the shear strength of the soil, whereas the normal stress and horizontal shear displacement amplitude significantly influenced the strain in the soil. Varying the normal and horizontal shear frequencies had little effect on the shear strength and strain of the soil. The normalized impedance and voltage of the SPGC, respectively, decreased and increased rapidly during the initial stage of the shear cycle; these changes were relatively small during the middle and late stages of the shear cycle. The SPGC voltage waveform revealed the changes in the shear stress and vertical displacement under different normal and horizontal shear frequencies, from which the stability of the subgrade soil under the aforementioned conditions could be evaluated. The variations in the SPGC impedance and effective voltage from the cyclic shear tests under both vertical static and vertical cyclic loads remained essentially consistent with the number of cycles. However, there was a difference in that the trough of the SPGC impedance under the vertical cyclic load was larger than that under the vertical static load; likewise, the effective SPGC voltage under the cyclic load was larger than that under the static load. Through an analysis of the SPGC impedance and voltage signals in the subgrade soil, the consistency of the SPGC-normalized impedance and effective voltage with shear stress was clarified; this helped us evaluate the health of the subgrade and monitor the characteristics of the precursor signals before a slide were to occur, thereby affording us an opportunity to issue timely warnings.

Motion speed control of magnetic microsphere robot under alternating signals

Gradient magnetic field driving method does not have strict structural requirements for micro robots, making processing convenient. However, the speed control parameter of micro robots under gradient magnetic fields is single, which limits the practical application of this type of robots. Therefore, this article proposes to use alternating signals to control the motion speed of magnetic microsphere robots. Here, a motion analysis model of a magnetic microsphere robot driven by alternating signals is established, and a formula for calculating the movement speed of the magnetic microsphere robot is provided. The special motion mode of the magnetic microsphere robot driven by alternating signals is considered, and the correctness of the theoretical calculation is verified by experiments. The mechanisms and conditions for the different motion modes of magnetic microsphere robots are revealed. The movement speed of the magnetic microsphere robot under the alternating voltage signals is determined as a function of signal frequency, signal duty cycle, and bias voltage value. The results show that under the alternating voltage signals, the magnetic microsphere robot has three different motion states, namely rotation -movement alternation, swing-movement alternation, and pure movement. There are three control parameters of the speed, which are signal change frequency, duty cycle, and bias voltage.