Voltage Generator Research Articles

A low-cost self-powered triboelectric nanogenerator sensor for detecting loosening bolt under impact loading

Purpose The purpose of this study is to detect the bolt loosening under conditions of impact loading with a low-cost self-powered triboelectric nanogenerator sensor. Design/methodology/approach In this work, an Al/PTFE-based triboelectric nanogenerator (AP-TENG) is used as a sensor. A pendulum impact device and a force hammer were used to apply the impact loads. The bolt status and the applied torque can be monitored under impact loading conditions by using the output voltage results of the AP-TENGs. Findings The output voltage results of the current AP-TENG sensor under five different bolt torques, i.e. from 0.5 to 2.5 N m, were measured. The measurements revealed that a thicker buffer layer significantly contributed to the generation of higher voltages. Besides, the AP-TENG was also used to light ten commercial green LEDs in series, and the brightness of the LEDs was high enough even for the daytime, which showed that it can be used as the alarm device. In addition, a sudden loose test was also carried out, and the obvious voltage spikes can be seen without the external impact. The force hammer impact tests have expanded the application scope of the AP-TENG in the bolt loosening detection. Originality/value The bolt loosening monitoring is important and useful for the safe operation. The application of TENG technology for detecting bolt loosening remains relatively unexplored. In addition, ten commercial green LEDs can be driven by the AP-TENG sensor, which can be used for the early warning of the bolted loosening status. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0216/

Jc(B) transformer rectifier flux pump optimisation via simulation

Abstract Superconducting power supplies commonly known as flux pumps are becoming viable products in various industries. In this work we investigate magnetically switched ( J c ( B ) ) half-wave transformer rectifier flux pumps (TRFPs) via a simulation previously validated against an experimental system. Upgrades to the model are introduced, namely the transition to a fully hysteretic transformer reluctance model and the introduction of a conduction cooling thermal model. The conduction cooling model allows direct comparison between liquid cryogen and conduction cooled systems, highlighting the distinct variations in response. This study focuses on parameter sweeps over some of the most important aspects of a TRFP such as; input power, cooling paths and switch length. The findings from these variable sweeps shed light on how to best design the different aspects of a TRFP for most applications and the conclusions drawn throughout this work can be applied to most TRFP types. Some of the major findings from this work are; i. the need for dedicated cooling busses in TRFP switches, ii. that increased switch lengths increase voltage generation but negatively impact cooling effectiveness iii. that the reduction of the metallic coatings surrounding commercial coated conductors results in larger switch voltages.

Modeling the effect of external load variations on single, serie and parallel connected microbial fuel cells

This paper presents a microbial fuel cell (MFC) model designed to analyze the effect of the external load on MFC performance. The model takes into account the voltage and the chemical oxygen demand (COD) dependence on the external load. The value of the model parameters were calibrated by means of the voltage relaxation method tests using a controlled load current. Laboratory measurements and MATLAB Simulink model computations were used to validate the proposed model. The tests results demonstrated that the proposed model accurately predicts the voltage and COD evolution during the batch cycle of the MFC. The root mean square error (RMSE) was used to assess the fitting goodness of the model. The RMSE of COD and voltage generation was in all the cases lower than 4%, predicting accurately the behaviour of single MFC as well as MFC connected in series or parallel.

Clean energy production and wastewater treatment by Exophiala dermatitidis: first findings

A single-chamber microbial fuel cell (MFC) was constructed to evaluate the capacity of Exophiala dermatitidis EXF-8193 as an electron-donor microorganism. The working electrodes were made of unidirectional carbon fiber and the voltage generation was evaluated for 120h. The maximum voltage value reached was 176mV after 93hours of operation. At the same time, the degradation of the Basic Blue 9 (BB9) was studied and a 70% decolorization was achieved in 120h. Optimization studies were conducted to maximize the electrical energy produced. In the first stage, the individual influence of the variables: carbon source, shape and area of the anode was analyzed. It was obtained that glucose, a T-shaped anode and an anodic area of 12 cm2 provided the best voltage values, generating 175.8 ± 0.57mV, 175.8 ± 0.57mV and 310.53 ± 1.22mV, respectively. In the second stage of the investigation, multiparametric optimization was carried out using the Response Surface Methodology (RSM) with a Box Behnken experimental design. A second-order model was the best fit, with R2 = 91.7. Finally, the MFC operation was optimized, with 284mV being the most favorable voltage when the cell is operated maintaining the optimal conditions for each parameter.

Clarify the process of overshoot voltage generation of proton exchange membrane electrolyzer under intermittent operation

Overshoot voltage phenomenon often occurs when the proton exchange membrane (PEM) electrolyzer is in the intermittent operation, which makes H2 production energy consumption increase significantly and its lifetime reduce rapidly, especially to the high-power electrolyzers in the industrial applications. Up to now, the phenomenon has been rarely understood and its process is elusive. Therefore, in this work, firstly, we find that the polarization curve of PEM electrolyzers happening S distortion synchronize with the appearance of overshoot voltage phenomenon. Secondly, through in-situ Raman characterization, we find that involvement and disappearance of H2O in the hydrogen evolution reaction (HER) is the key factor causing and resolving this phenomenon. Finally, we used EPMA to exclude metal cations affection. Also, by micro-CT, EIS test, visualization PEM electrolyzer inside model and COMSOL electromagnetic simulation, we find that anode catalyst layer porosity reduction directly affects water absorption of membrane as well as current variation leads to eddy currents generation which is deepen unequal current distribution. These are two important reasons for the involvement of H2O in HER. In summary, these findings elucidate the mechanism of overshoot voltage phenomenon for the first time, which contributes to design novel electrical protection schemes and advanced membrane electrodes for PEM electrolyzers, thus they can help to achieve cost reduction and efficiency improvement in the green hydrogen industry.

A Novel Development of Soft Computing based Hybrid Power Point Tracking Controllers for Hydrogen Vehicle Application with New Wide Source DC-DC Converter

From the present power generation scenario, most of the power production companies are focusing on renewable energy systems because their merits are easy to install, more reliable power sources, free from atmospheric pollution, and better adaptable to all weather conditions. In this article, a Polymer Electrolyte Membrane Fuel Cell (PEMFC) module is selected in the first objective to produce constant and continuous power to the hydrogen-based electrical vehicle systems. This fuel module provides fast power production and gives good energy density. However, the demerits of this module are more current production and low-level voltage generation. A new single-switch DC-DC circuit is introduced in the second objective of this work for optimizing the current levels of the fuel module thereby reducing the source power loss of the proposed system. Here, another problem of the fuel module is nonlinear power production which is linearized by proposing the Cuckoo Search Optimization (CSO)-based Adaptive Network-based Fuzzy Inference System (ANFIS) in the third objective to extract the maximum voltage from the fuel module. The merits of this introduced Maximum Power Point Tracking (MPPT) Controller are better tracking speed, low-level disturbances in the consumer load power, high robustness, more sustainability, and easy operation. The entire proposed system is investigated by selecting the MATLAB Simulink tool. The introduced converter circuit is analyzed by selecting the programmed DC supply.

Self-powered wireless sensing system with cylindrical high voltage side electric field energy harvesting by discharge circuit

To warn of overcurrent heating, temperature wireless sensor node (WSN) need to be deployed on the overhead lines of the power grid. The sustainable power supply of WSN is difficult. Using the electric field energy around the transmission line to power the sensor has the advantages of stability, reliability and sustainability, but the electric field energy harvesting (EFEH) power need to be improved. This paper studies the principle of energy harvesting by displacement current and discharge method, and analyzes the influencing factors of the output power of the EFEH unit. The power improvement method of the EFEH unit is proposed by improving the coupling capacitor and the energy storage capacity discharge voltage. The relationship between the structural parameters of energy cylinder and induced potential and coupling capacitance is explored by COMSOL simulation software. A low-cost, self-driven and adjustable high voltage undervoltage lock (UVLO) circuit is proposed. A 10kV high voltage generation platform is built in the laboratory, and the wireless temperature and humidity sensor is self-powered by the EFEH with power of 2.04mW. This research has important theoretical and application value for the high voltage side EFEH powered WSN.

Spider Webs‐Inspired Aluminum Coordination Hydrogel Piezoionic Sensors for Tactile Nerve Systems

AbstractPiezoionics, a new frontier that employs mobile ions as energy and charge carriers, plays an important role in new energy and intelligent electronics. However, a significant challenge consists in balancing the structural design of metal ions coordination hydrogel (HG‐MI) piezoionics for current conduction, voltage generation, and especially mechanical adaptability. Herein, inspired by the spider webs' unique structure, a strategy by realizing the full potential of metal‐ligand ions ([(OH)Cl2]3−) to facilitate the keggin‐type structure AlOHAlOH generation together with activate functional carboxyls is introduced. Impressively, the whole property of the product HG‐AlPAC, especially the mechanical performance is improved. For example, the toughness of HG‐AlPAC is 2.75 MJ m−3, more than twofold that of traditional HG‐AlAS/AC/AN samples. Due to the stable fixation of ─Al─OH─ thus promoting Cl− separation upon external force, HG‐AlPAC achieves a piezoionic coefficient of 0.89 mV KPa−1 and energy conversion efficiency of 1.29%, promising for mechanical‐electrical conversion and sensing. Combined with the good mechanical performance with the excellent piezoionic properties, underscores its potential as a tactile nerve system of analgesia patients to prevent them from being injured. This work intends to provide a stride toward mechanically robust self‐powered piezoionic sensors and offer insights into ionotropic materials for energy harvesting, human‐machine interaction, and biointerface.

Investigating the correlation between flow dynamics and flow-induced voltage generation

The conversion of water current to voltage generation through graphene has gained interest in both basic physics and applications such as sensors and electricity generation systems. However, many aspects of the mechanism remain unclear. Recently, quantum-based momentum transfer theories have been reported, but these often do not account for flow conditions. In this study, we investigated the correlation between the flow conditions of a liquid medium and the electrical conduction of graphene through experiments and numerical calculations. Our results suggest that the necessary condition is that the flow must be neither irregular nor purely laminar; instead, graphene responds to the transition process of the fluid. This finding supports the extension of current theories and presents valuable insights for both basic science and industrial applications.

From Sudoscan to bedside: theory, modalities, and application of electrochemical skin conductance in medical diagnostics.

The human body has two main types of sweat glands: apocrine and eccrine. Eccrine glands are widely distributed across the skin, including areas with hair. While the eccrine glands on palms and soles help improve grip, those on the rest of the body primarily aid in thermoregulation. Sudomotor function, which controls sweating, is regulated by the sympathetic division of the autonomic nervous system through cholinergic and adrenergic pathways. The activation of eccrine glands involves intricate processes, including neurotransmitter binding, ion channel modulation, and voltage generation. Sudoscan technology utilizes electrochemical skin conductance (ESC) to non-invasively measure sudomotor function. This method, which has been standardized for accuracy, has established normative benchmarks and has proven reliable across diverse populations. Sudoscan's diagnostic performance is comparable to invasive methods such as intraepidermal nerve fiber density testing, making it a valuable tool for diagnosing small fiber neuropathy. Moreover, it has been shown to correlate with corneal nerve fiber length, providing insights into various neuropathic conditions. Compared to traditional sudomotor function tests, Sudoscan proves superior in terms of its accessibility, simplicity, and reliability, with the potential to replace or complement existing diagnostic methods. It is important to differentiate ESC, as measured by Sudoscan, from other skin conductance measures, such as galvanic skin response (GSR) or electrodermal activity (EDA). Although these methods share a common physiological principle, ESC is specifically designed for diagnosing sudomotor function, unlike GSR/EDA, which is typically used for continuous monitoring. Sudoscan's success has led to its integration into consumer health devices, such as the BodyScan from Withings, showcasing its versatility beyond clinical settings. Future research may explore ESC applications in diverse medical fields, leveraging real-world data from integrated consumer devices. Collaborative efforts between researchers and engineers promise to offer new insights into sudomotor function and its implications for broader health monitoring. This study provides a comprehensive overview of ESC, including topics such as eccrine gland physiology, sudomotor function, Sudoscan technology, normative benchmarks, diagnostic comparisons, and potential future applications.

Electrochemical kinetic energy harvesting mediated by ion solvation switching in two-immiscible liquid electrolyte

Kinetic energy harvesting has significant potential, but current methods, such as friction and deformation-based systems, require high-frequency inputs and highly durable materials. We report an electrochemical system using a two-phase immiscible liquid electrolyte and Prussian blue analogue electrodes for harvesting low-frequency kinetic energy. This system converts translational kinetic energy from the displacement of electrodes between electrolyte phases into electrical energy, achieving a peak power of 6.4 ± 0.08 μW cm−2, with a peak voltage of 96 mV and peak current density of 183 μA cm−2 using a 300 Ω load. This load is several thousand times smaller than those typically employed in conventional methods. The charge density reaches 2.73 mC cm−2, while the energy density is 116 μJ cm−2 during a harvesting cycle. Also, the system provides a continuous current flow of approximately 5 μA cm−2 at 0.005 Hz for 23 cycles without performance decay. The driving force behind voltage generation is the difference in solvation Gibbs free energy between the two electrolyte phases. Additionally, we demonstrate the system’s functionality in a microfluidic harvester, generating a maximum power density of 200 nW cm−2 by converting the kinetic energy to propel the electrolyte through the microfluidic channel into electricity.

Green conversion of waste polyester into few-layer graphene for interfacial solar-driven evaporation and hydroelectric electricity generation

The coupling of solar-driven interfacial evaporation with hydrovoltaic technology is emerged as a hopeful approach to alleviate energy crisis and freshwater shortage. However, constructing low-cost evaporators with high-performance freshwater and electricity co-generation and unveiling the co-generation mechanism remain a grand challenge. Herein, we report the green transformation of waste poly(ε-caprolactone) into graphene through a salt-assisted carbonization strategy and build a flexible bi-functional graphene-based evaporator for freshwater and electricity co-generation. The graphene exhibits a typical wrinkled structure with curved edges and is composed of 7–8 discontinuous layers with rich oxygen-containing groups. The graphene-based evaporator exhibits excellent sunlight absorption (98%), photo-to-thermal conversion property, good water transport ability, low water evaporation enthalpy, and low thermal conductivity of 0.06 W m−1 K−1. The evaporator not only exhibits a notable water evaporation rate (2.92 kg m−2 h−1), but also achieves the maximum output voltage of 310 mV, surpassing many previously reported evaporators/generators. The result of molecular dynamics simulation proves the diffusion difference between H+ and OH− in water and graphene, which eventually leads to the voltage generation. Not only will this work help to improve the upcycling of waste plastics and achieve carbon neutrality, but it will also open an avenue for co-generation of freshwater and electricity.

Enhanced methane and energy generation from sewage water using microbial fuel cells with paddy field soil substrate

Microbial fuel cells (MFCs) have potential in wastewater treatment, biogas production and clean energy generation. MFCs provide an interdisciplinary research approach incorporating engineering and natural sciences. This study explores MFCs’ capabilities to produce electricity and biogas from wastewater and field soil substrates with different compositions. A two-chamber MFC system was operated anaerobically. Household sewage water used as the organic substrate with different soil amounts. Six different process feed compositions, labeled MFC-1–6, were investigated. MFC-1 exhibited the highest biogas generation volume of 245 cm³ and 42 mW/cm² power density. MFC-5 and −6 yielded 100 cm³ and 130 cm³, respectively. Wastewater treatment was effective on day 20, with pH, conductivity, turbidity, and total dissolved solids decreased to 7.3, 2.6 mS, 326 NTUs, and 1114 mg/L, respectively. Since, MFC-1 autonomously generated −800 mV, an external battery supplied an additional 600 mV to meet the methane generation voltage requirements. MFCs’ effectiveness in addressing wastewater treatment and renewable energy production was highlighted.

Thermally Driven Spin Transport of Epitaxial FeRh Films with a Non-magnetic Pt Layer via the Longitudinal Spin Seebeck Effect.

FeRh has been demonstrated to be an important material for the observation of magnetic phase transitions, such as the first-order transition from an antiferromagnetic (AFM) to a ferromagnetic (FM) state, in response to changes in the temperature. This is because of the magnetic moment induced in Rh atoms above the magnetic phase transition temperature. In the present study, we focus on the longitudinal spin Seebeck effect (LSSE), which involves the generation of spin voltage as a result of a temperature gradient in FM materials or FM insulators, and experimentally assess the effect of the crystalline quality of FeRh films and the properties of the substrate on the LSSE thermopower during the FM-AFM phase transition. The measured LSSE thermopower of an epitaxial (110)-oriented FeRh film grown on an Al2O3 substrate is approximately 60 times higher than that of a polycrystalline FeRh film on a SiO2/Si substrate. This can be explained by the high magnetic sensitivity and superior FM properties of (110)-oriented epitaxial FeRh films. Furthermore, by comparing the transverse thermoelectric voltage for in-plane magnetized (IM) and perpendicularly magnetized (PM) configurations, we quantitively evaluate the contribution of the exclusive anomalous Nernst effect (ANE) to the LSSE signals in the FeRh/Al2O3 structure, finding it to be approximately 15-30% over a temperature range of 75-300 K. LSSE measurements in Pt/FeRh films are thus demonstrated to provide a versatile pathway for the development of thermoelectric power generation applications and other practical spintronics and neuromorphic computing devices.

Generating comprehensive lithium battery charging data with generative AI

In optimizing the performance and extending the lifespan of lithium batteries, accurate state prediction is crucial. Traditional regression and classification methods have achieved some success in predicting battery states. However, the effectiveness of these data-driven approaches largely depends on the availability and quality of public datasets. Additionally, generating electrochemical data primarily through battery experiments is a lengthy and costly process, making it extremely difficult to obtain high-quality data. This difficulty, combined with data incompleteness, significantly affects prediction accuracy. To address these challenges, this study introduces End of Life (EOL) and Equivalent Cycle Life (ECL) as supervised conditions for generative AI models. By integrating an embedding layer into the CVAE model, we developed the Refined Conditional Variational Autoencoder (RCVAE). Through preprocessing data into a quasi-video format, coupled with customized training and inference algorithms, the RCVAE generates the required charging data in real time based on the battery’s ECL and EOL. This avoids storing irrelevant information, saving space and resources. RCVAE uses a lightweight architecture, enabling fast generation of necessary voltage, current, temperature, and charging capacity data. This approach provides users with a comprehensive electrochemical dataset, pioneering a new research domain for the artificial synthesis of lithium battery data. Furthermore, based on the detailed synthetic data, various battery state indicators can be calculated, offering new perspectives and possibilities for lithium battery performance prediction.

Polymerized lignin based carbon nanofiber for high-performance energy generator and storage

Lignin is an ideal precursor for the preparation of lignin-based materials. However, the lack of molecular weight, thermal stability and spatial configuration of lignin hinder the practical application of lignin in lignin-based carbon materials. Herein, a novel and effective strategy for preparing high-performance lignin-based carbon nanofibers (CFs) is designed. Lignin samples with different chemical structures are prepared by polymerization modification and fractionation. This strategy completely gets rid of the dependence on petroleum-based polymers in the electrospinning process, and makes the lignin-based CFs show good performance in energy storage, temperature sensor, and moisture power generation. The specific capacitance and energy of lignin-based supercapacitors reach 357.2 F/g and 31.5 Wh/kg, respectively. The CFs exhibit good flame retardancy and thermal sensitivity, and the response time is 1 s. In addition, moisture power generators assembled with CFs exhibit great potential. The output voltage of moisture power generators has a linear relationship with the number of devices. With the increase of series equipment, the output voltage of 5 series moisture power generators is 4.7 V. This work provides a new approach to prepare high-performance lignin-based carbon nanofibers, which has a good application prospect in the fields of energy storage, sensing and power generation.

Conjunctive optimal operation of water and power networks

Water distribution systems (WDSs) are designed to convey water from sources to consumers. Their operation is a main concern for engineers, researchers, and practitioners and is subject to demand, pressure, and quality constraints. Pumping stations require power to pump water and keep system pressure at a desired level. On the other hand, power is generally supplied through power grids (PGs), which require optimal operation while satisfying operational constraints, such as generation limits, power consumption, and voltage constraints. Since the two infrastructure systems are interconnected, decision-makers could benefit from a holistic approach that would allow solving the two operational optimization problems together as one conjunctive problem. This paper presents the full mathematical formulation of the conjunctive optimization problem, including a novel modelling approach for the operation of a variable speed pump, which does not include integer variables for pump status, thus allowing to solve the model as a non-linear programming (NLP) problem. The formulation is applied to two illustrative case studies, and the results are compared to the optimal operation of the independent WDS. The inclusion of the PG in the optimization problem is observed clearly in the results and influences them quite significantly. WDS operation is shown adjust to the PG constraints, and the application of the conjunctive model results in a cost reduction rate of more than 10 % for both case studies.

Energy harvesting by car-tire using piezoelectric polymer films blended with carbon-nanotubes

Energy harvesting through harnessing mobile cars is possible by combining mechanicals systems with advanced materials. Piezoelectric polymer blends with excellent mechanical properties facilitate energy harvesting using the car-tire as a source. Furthermore, by adding simplicity of preparation to the blends with multi-walled carbon nanotubes (MWCNT), an increase of energy conversion can lead to improved existing polyvinylidene fluoride/polymethylmethacrylate (PVDF/PMMA), films. This work focuses on investigating the best concentration of MWCNT to achieve car-tire energy harvesting as a sustainable and renewable energy option. The results show that 0.05 wt% of MWCNT is the best concentration among several values. A test set-up applying normal stress, simulating car-tire deformation indicated enhanced voltage generation. Compared to the energy consumption of combustion cars, the enriched films generate up to 4.3kWh. This energy is harvested over a car trip of 100 km. A higher nanotube concentration caused saturation of the blend film and poor output. The novel enriched polymer must be tested for resisting cyclic loads to encourage sustainable energy harvesting using car tires.

Enhanced performance of cyclone separator through coupling of centrifugal force, electrostatic force and particle pre-charge

The electrostatic enhancement can effectively improve the performance of cyclone separator at low load or high-temperature, but its application is limited owing to the reduction of spark voltage in high-temperature. Aiming at this question, a new technology coupling centrifugal force, electrostatic force and particle pre-charge was proposed. The characteristics of particles charging and agglomeration were analyzed, and the influence of different factors on the change of particle partition number concentration and total removal efficiency of cyclone separator were studied. The results showed that, increasing the charge generator voltage and decreasing the main pipe gas velocity can increase the particles charge quantity and improve agglomeration, which is benefit for the efficiency improvement of either cyclone separator or electrostatic cyclone separator, especially at low inlet gas velocity. Higher charge generator voltage and lower inlet gas velocity, more obvious efficiency improvement. The total removal efficiency can be increased by up to 10 % and 9 % respectively for the cyclone separator and electrostatic cyclone separator because of particle pre-charge at 10 m/s of inlet gas velocity, and the removal efficiency of fine particles can also be effectively improved. Comparing with the electrostatic cyclone separator, achieving the same total removal efficiency, the internal voltage can be reduced 16 kV through particle pre-charge. The electrostatic force and centrifugal force were the main factor of the small particles and big particles removal, respectively.

Implementation Joule Thief Buck-Boost Converter in A Neodymium Wind Power Plant

Wind power generation is gaining popularity as an environmentally friendly renewable energy source. However, the output voltage of a wind generator usually varies according to the wind speed, requiring a power converter to produce a stable DC voltage. The author of this research aims to implement a Joule Thief Buck-Boost Converter on a neodymium wind power generation system. Joule Thief is a DC-DC converter that has the ability to convert a low input voltage into a higher output voltage, and can maintain a relatively stable output voltage despite changes in the input voltage. In this study, a Joule Thief buck-boost converter is used to regulate the output DC voltage of the neodymium wind generator to remain stable despite the changing wind speed. System testing is done by measuring the output voltage of the neodymium wind power plant. The test results show that the Joule Thief Buck-Boost Converter can maintain the output DC voltage at a stable value of 14V at input voltages above 3V, so the implementation of this converter in neodymium wind power plants is proven effective in producing a stable DC voltage. This research is expected to contribute to the development of a more efficient and reliable wind power generation system.