Maximum Voltage Value Research Articles

Triboelectric nanogenerators for blue energy harvesting in simulated wave conditions

Energy harvesting gadgets gained momentum with the proposal of triboelectric nanogenerators (TENGs). They can be used to efficiently convert otherwise wasted surface and underwater waves into electricity to power marine-based devices and equipment without greenhouse emissions. In this study, a commercial buoy is modified and a pendulum-like TENG is proposed for ocean wave energy harvesting. Polyurethane (PU) foam and poly(dimethyl siloxane) (PDMS) were utilized as triboelectric couple. From the measurements taken under simulated real case situations in a wave flume, maximum voltage and current values were recorded as 145 V and 8.9 µA, respectively, with a maximum power output of 1.1 W/m2. No performance loss was observed even after 1200 cycles of stability measurement. While presenting the results from the simulated environment, this study highlights and reveals the importance of measurements taken in real situations for understanding the effectiveness of the wave energy harvesters.

"Clickable" Organic Electrochemical Transistors.

Interfacing the surface of an organic semiconductor with biological elements is a central quest when it comes to the development of efficient organic bioelectronic devices. Here, we present the first example of "clickable" organic electrochemical transistors (OECTs). The synthesis and characterization of an azide-derivatized EDOT monomer (azidomethyl-EDOT, EDOT-N3) are reported, as well as its deposition on Au-interdigitated electrodes through electropolymerization to yield PEDOT-N3-OECTs. The electropolymerization protocol allows for a straightforward and reliable tuning of the characteristics of the OECTs, yielding transistors with lower threshold voltages than PEDOT-based state-of-the-art devices and maximum transconductance voltage values close to 0 V, a key feature for the development of efficient organic bioelectronic devices. Subsequently, the azide moieties are employed to click alkyne-bearing molecules such as redox probes and biorecognition elements. The clicking of an alkyne-modified PEG4-biotin allows for the use of the avidin-biotin interactions to efficiently generate bioconstructs with proteins and enzymes. In addition, a dibenzocyclooctyne-modified thrombin-specific HD22 aptamer is clicked on the PEDOT-N3-OECTs, showing the application of the devices toward the development of organic transistors-based biosensors. Finally, the clicked OECTs preserve their electronic features after the different clicking procedures, demonstrating the stability and robustness of the fabricated transistors.

Implementation of class‐E/F3 power amplifiers based on the variations of the MOSFET grading coefficient, built‐in potential and output capacitance along with their roles in MOSFET selectivity

SummaryIn this paper, a theoretical analysis of the class‐E/F3 power amplifier based on the variation of the grading coefficient m1 and its vital role in MOSFET selectivity to operate safely under given design specifications is presented while the nonlinearity of the drain‐to‐source capacitance is considered. Moreover, the importance of Vbi and Cjo in designing the class‐E/F3 amplifier is investigated. To clarify how the grading coefficient m1 and the other mentioned parameters can directly influence the power amplifier performance and also its elements, these MOSFET parameters are considered as the independent variables of the calculated equations and consequently define the horizontal axis of the obtained plots. Accordingly, as the grading coefficient increases, the maximum switch voltage increases and values of the output power and output power capability decline. Moreover, to prove the reliability of the carried‐out analysis in selecting proper MOSFETs, the performances of three amplifier samples utilizing IRF510, IRFZ24N, and 2SK2504 MOSFETs with different grading coefficient m1 and almost similar Vbi and Cjo are studied. Then, by comparing the results of amplifiers with three MOSFETs, IRF510, IRF530, and IRF540, with similar grading coefficient and different values of Vbi and Cjo, the significance of considering the values of Vbi and Cjo is investigated. Eventually, three amplifiers with 2SK2504, IRF510, and IRF530 MOSFETs have been simulated, implemented, and tested and measurement results agreed well with the theoretical and simulation results.

Experimental and theoretical analysis of thermoelectric energy generating system collecting concentrated solar energy

ABSTRACT In this study, the electrical energy production limits of a thermoelectric generator in a system providing high thermal efficiency were investigated. Linear Fresnel lenses and solar glass tubes were used as solar concentrator and collector in the system. In order to achieve maximum efficiency from solar radiation, one-axis and two-axis solar tracking systems were used. Experimental measurements were performed for both one-axis and two-axis solar tracking systems at the location 41 14’ N and 36 26’ E. In addition to the experimental study, a numerical model consisting of TEG (Thermoelectric Generator) and cooling system was also developed. The values of parameters such as open-circuit voltage, wind speed, temperature, solar irradiance were collected during the experiments. Pure water and acetone were used as working fluids in the heat pipes in the system. As a result of all these processes, the maximum open-circuit voltage values obtained in the thermoelectric generator mounted on the head of the heat pipe were determined as 3.45 Volt for pure water and 3.03 Volt for acetone, respectively. The numerical model was validated according to cold side temperature and open-circuit voltage obtained from twelve experimental cases performed on different dates. Cold side temperature and open-circuit voltage at the hot surface temperature of 144.2℃, the highest temperature among these experimental cases, were calculated as 2.95 V and 93.14℃, respectively. In this case, the error between the numerical and experimental results was 7.5% for the open-circuit voltage and 4.5% for the cold side temperature. As a result, it was seen that the experimental measurements and the numerical results were in good agreement.

Pulsed Charging Protocols with Non-Zero Relaxation Time for Lithium-Ion Batteries

Lithium-ion batteries are commonly charged following the constant current -constant voltage (CC-CV) protocol. Current flow during charging implies an equivalent ionic flow through the battery materials. Intercalation and de-intercalation of Li+ are accompanied by concentration gradients that are reflected by the rise in the cells’ potentials that is required to maintain the constant current during the CC regime. In this work, two new pulsed charging protocols were tested. Firstly, a square current pulse is applied to the cell until the cut-off voltage is reached, followed by a pulsed square voltage protocol (PV). The second methodology keeps the same current pulse, however, after the limiting voltage was reached, the pulsing regime consisted in alternating between a maximum voltage value and a minimum, non-zero, constant current value. Different voltage pulse widths and frequencies were tested, in order to study the maximum electrodes’ capacity, the time required to reach that capacity, the contribution of each individual step (i.e. PC and PV) to the total electrodes’ capacity, and the thermal variations for each. The second pulsing mode produced capacity values 7%–8% higher than in the classical CC–CV protocol, and in charging times periods from 5%–25% faster, without compromising the batteries’ cycle life.

Damage Detection Test of GFRP Composite Civil Materials Based on Piezoelectric Ceramic Sensors

The piezoelectric ceramic sensor was fixed on Glass Fiber Reinforced Plastic (GFRP) composite civil materials, using the external paste method for damage detection test. The effect of the depth and number of cracks on the surface of the GFRP specimen on the signal received by the piezoelectric ceramic sensor was studied. The time-domain signal graph and energy graph based on wavelet packet were drawn, combining the active induction method and the energy method based on wavelet packet. It is found that the greater the damage degree of GFRP specimens, the smaller the voltage value of the signal, the smaller the energy of the signal, and the greater the damage index based on wavelet packet. The results showed that the active induction method can be used to collect the data of GFRP specimens by piezoelectric ceramic sensor. The collected data are processed by using the damage index principle based on wavelet packet. The maximum voltage value of the specimen, the energy of wavelet packet, and the damage index based on wavelet packet can all accurately judge the damage change of GFRP specimens. The active induction method based on piezoelectric ceramic sensor can detect the damage change of GFRP specimens in real time. It provides an effective method for damage analysis of GFRP composite civil materials.

Digital Pregnancy Test Powered by an Air-Breathing Paper-Based Microfluidic Fuel Cell Stack Using Human Urine as Fuel.

The direct integration of paper-based microfluidic fuel cells (μFC’s) toward creating autonomous lateral flow assays has attracted attention. Here, we show that an air-breathing paper-based μFC could be used as a power supply in pregnancy tests by oxidizing the human urine used for the diagnosis. We present an air-breathing paper-based μFC connected to a pregnancy test, and for the first time, as far as we know, it is powered by human urine without needing any external electrolyte. It uses TiO-Ni as anode and Pt/C as cathode; the performance shows a maximum value of voltage and current and power densities of ∼0.96 V, 1.00 mA cm, and 0.23 mW cm, respectively. Furthermore, we present a simple design of a paper-based μFC’s stack powered with urine that shows a maximum voltage and maximum current and power densities of ∼1.89 V, 2.77 mA cm and 1.38 mW cm, respectively, which powers the display of a pregnancy test allowing to see the analysis results.

Direct Energy Conversion from <i>Metroxylon sagu</i> via Multienzyme Catalysis in Enzymatic Biofuel Cell

Biomass substrates have been used extensively in the production of biofuel by the simultaneous saccharification and fermentation (SSF) method. Biomass sources from the plant are preferable to produce biofuel because of the high sugar content. Adapting the SSF method, this work reported on the direct energy conversion from Metroxylon sagu via multienzyme catalysis in an enzymatic biofuel cell (EBFC). Metroxylon sagu locally called Sago is an industrial crop mainly found in Mukah, Sarawak. Sago is a type of starch that consists mainly of amylose and amylopectin structures. In this study, the polysaccharides are converted to glucose using alpha-amylase (α-amylase) and glucoamylase (GAmy) enzymes. The factors influencing the multienzyme catalysis, such as the substrate concentration, enzymes loading, pH and time, were varied to obtain the optimized condition for glucose production. The results of the glucose content using a microplate reader indicate that glucose was successfully produced via multienzyme catalysis. The oxidation of glucose employed in the EBFC was confirmed by the cyclic voltammogram (CV) analysis. The performance of EBFC was also assessed based on its maximum power density (MPD) and open circuit voltage (OCV) values. This multienzyme catalysis simplifies the multi-step process involved in converting polysaccharides to glucose.

Influence of sample thickness and cross-sectional area on flexoelectric effect under one-dimensional impact

The shock wave generates the strain gradient and consequent electric polarization in samples due to the flexoelectric effect during the impact process. At present, some scholars have studied the influence law of different impact velocities, but the influence of different thickness and cross-sectional area of samples on flexoelectric effect is still blank. In this letter, we have studied the voltage variation of barium titanate samples with different thickness and cross-sectional area under a certain impact velocity. The results show that the maximum voltage value caused by flexoelectric effect increases as the thickness increases, which is basically in positive proportion; it decreases with the increase of diameter, which is in inverse proportion. This research will lay a theoretical foundation for the fabrication of flexoelectricity sensor.

First Principles Study of Layered CrGeTe3 as Lithium Intercalation Compound

There have been unprecedented research efforts to produce efficient and sustainable electrode materials for lithium-ion batteries (LIB). The research efforts to increase energy density, life cycle, safety, and rate-capability are still in progress. This work is carried out to explore the prospects of a new anode material CrGeTe3 for use in LIB studied via first-principles predictions. The investigation of Li: CrGeTe3 system and lithiation mechanism in the proposed material pointed out its suitability for lithium intercalation compound. The energy-profiling at highly symmetry points in the host structure revealed that BGe-Cr is most favorable energy site for lithiation in the material. The maximum value of the lithium insertion voltage is 3.41 V and the storage capacity is 620.60 mAh g−1. The diffusion barrier faced by lithium atom is 0.27 eV which is the minimum value, while moving along the x-axis within the top and middle hexagonal rings. The steric interaction of Li with Ge and Te atoms pointed structural reliability and hence stable operation of the anode to address capacity fading problems in LIB.

Piezoelectric and magnetoelectric properties of PVDF/NiFe2O4 based electrospun nanofibers for flexible piezoelectric nanogenerators

In this study, flexible piezoelectric nanogenerators (PNGs) were fabricated using the composite fibers which were prepared by combining polyvinylidene difluoride (PVDF) and nickel ferrite (NiFe2O4) nanoparticles (NPs) at a concentration of 1, 3, 5, 7, and 10 wt%. The piezoelectric properties of PNG indicate that the PVDF/NiFe2O4 fibers containing NiFe2O4 NPs at a concentration of 10 wt% has a higher power efficiency of 5.4% at 20 Hz compared to that of the pure PVDF fibers at 10 Hz, under the same resistive load of 2.5 MΩ. The magnetoelectric properties of PNG show that the PNG with PVDF+7 wt%NiFe2O4 supplied the highest electrical power of 0.40 μW under a resistive load of 750KΩ while it reached a maximum voltage value of 17.50 mV at the same load resistive load for a low-level magnetic field of 50 Hz frequency.

Experimental research and artificial neural network prediction of free piston expander-linear generator

For the purpose of better matching the performance of the organic Rankine cycle (ORC) system concerning the vehicle engine waste heat recovery, this paper studies the output performance of free piston expander-linear generator (FPE-LG). A test bench of FPE-LG is established for small scale ORC system, and timing and displacement control strategy is proposed. Furthermore, the impact of the intake pressure and the torque on motion characteristics and output performance of FPE-LG are analyzed. According to evaluating different learning rates, number of hidden artificial neural networks and training functions, a prediction model of FPE-LG based on artificial neural network is established. Genetic algorithm is used to optimize the key operating parameters, to maximize the power output of FPE-LG. In consideration of the mean square error and determination coefficient, the artificial neural network model is verified and tested by experimental data. Finally, combining genetic algorithm with artificial neural network model, the maximum power output of FPE-LG is optimized and its performance is predicted. The results show that the maximum value of electric current, voltage and power output are 2.8 A, 14.75 V and 28.5 W, respectively. Based on artificial neural network, this method can provide useful guidance for performance prediction and coordinated optimization, with advantages of minimum deviation and high precision.

Схема самозапуска для тиратрона в составе высоковольтного импульсного генератора

The paper describes a self-triggering circuit for a TDI4-200k/50SN thyratron operating as part of a high-voltage pulse generator built on the basis of a pulse transformer. Thyratrons of this series have a number of advantages. They allow switching current up to 200 kA with a frequency of up to 300 pulses per second, do not require maintenance, are produced in versions with a heated cathode and instantaneous readiness. Also, if there are no strict requirements for the turn-on delay, these thyratrons are not too demanding on the parameters of the triggering pulse. This allows one to implement a fairly simple and not demanding to the element base scheme for their triggering. The peculiarity of the proposed self-triggering circuit is its complete autonomy, automatic generation of a triggering pulse at the moment of the maximum voltage value on the main capacitance, as well as simplicity and reliability. It is shown that the triggering time delay and the triggering time jitter of the thyratron do not exceed 1.6 µs and 0.6 µs, respectively.

Structure simulation design of a cathode air filter for SO2 contamination on a 7 kW fuel cell sightseeing vehicle

Proton exchange membrane (PEM) fuel cell stacks can be severely poisoned by a trace amount of SO2 in the atmosphere, making it necessary to install an air filter to remove harmful contaminants from the cathode air. This study utilizes Computational Fluid Dynamics (CFD) to investigate the influence of the diverse filter structure design containing combinations of inlet diversion tube length and outlet deflector shape on the hydrodynamics and adsorption performance of a cathode air filter by Fluent. Simulation results show that the air filter performance is enhanced with decreases in diversion tube length. Compared with the horizontal porous plate, the conical one increases the pressure drop and the SO2 adsorption dead zone area. Besides, an air filter prototype made based on the simulation results was applied to a 7 kW fuel cell sightseeing vehicle for the field test. The maximum voltage value of the stack is 73.1 V, the minimum is 67.6 V, and the maximum difference is 5.5 V when the fuel cell sightseeing vehicle runs at a constant speed of 20 km/h 77% of the voltage value is stable between 69 and 71 V, which proves the stable operation of the stack.

Analyses and Comparisons of Generic and User Writing Models of HVDC System Considering Transient DC Current and Voltages

Analyses and comparisons of generic models and a novel modeling method of line-commutated converter (LCC)-based high voltage direct current (HVDC) systems are presented for the power system simulator for engineering (PSS/E) simulation tool. The main purposes are to describe the dynamics of the DC voltage and current of HVDC system and to improve estimation of the maximum values using the generic and proposed HVDC models when AC line-to-ground faults are occurred. For the generic HVDC models, the characteristics and limitations as well as parameter investigations are conducted. Three modules are also are developed for the proposed HVDC model, which are composed of (a) AC/DC conversion; (b) controller selection; and (c) DC line model. Case studies were conducted considering the real-operated HVDC system in Korea under the PSS/E and power systems computer aided design (PSCAD) simulation environments. The simulation results were compared with measured data from the real-operated HVDC system and the results from the PSCAD HVDC models considering single- and three-phase line-to-ground faults. The case study results show that a specific generic HVDC model in PSS/E can simulate the dynamics of the DC voltage and current after the AC line-to-ground faults. The case studies also showed that the proposed modeling method is effectively improves the estimation of the maximum DC voltage and current values for the AC line-to-ground faults.

RANCANG BANGUN PEMBANGKIT LISTRIK TENAGA SAMPAH (PLTSa) DI LINGKUNGAN STT MIGAS BALIKPAPAN

The Environment and Forestry Metrics stated that data on waste piles in Indonesia in 2020 reached 67.8 tons, 45% of which was poorly managed plastic waste. The large amount of waste produced causes Indonesia to become the second waste producer in the world. The level of waste management that is still minimal is the main thing that causes Indonesia to become a "polluting" country in the world. Waste Power Plant is a waste management solution to reduce the amount of waste and become an alternative energy for generating electricity in the community. The purpose of this research is to provide an alternative by creating a waste power plant as a producer of renewable electrical energy. This research begins with collecting materials and continues with the design of components such as furnaces, boilers, steam turbines, DC generators which are integrated into one, and waste as fuel. The components that have been worked are then tested with plastic waste and wood waste are collected and then put into the furnace, then the waste is burned to boil water in the boiler. Changes in the speed or relative velocity of this steam cause a force turns the turbine. The turbine that is connected to this generator will then rotate the generator to produce electricity. Based on the results of testing the solid waste power plant, the maximum voltage value is 13.76 V.

Towards a safe failure mode under short-circuit operation of power SiC MOSFET using optimal gate source voltage depolarization

This paper focuses on the enhancement of the robustness level of SiC MOSFET during short-circuit conditions. In this study, two approaches allowing to ensure safe “Fail-To-Open” (FTO) mode in planar power SiC MOSFET devices under short-circuit operation are presented. These approaches are based on direct depolarization of the gate source voltage and its estimation from the calculation of the critical dissipated power (W/mm2) between FTO and classical unsafe thermal runaway. They allow to determine the maximum value of the gate source voltage to preserve a FTO mode under a drain source voltage close to the nominal value i.e. VBRmin/2. The boundary of the power density between FTO and “Fail-To-Short” (FTS) is introduced. A complete experimentation of the two failure modes in competition that may appear during short-circuit (SC) test of 1.2 kV SiC MOSFETs is presented. Finally, the penalty of the gate source voltage depolarization on the on-state resistance (Rds(on)) is investigated in order to evaluate the techniques efficiency.

Electromechanical simulation and analysis of perovskite piezoelectric ‎unimorph cantilever nanogenerator with interdigitated electrodes in ‎vibration energy harvesting application

This paper addresses a unimorph cantilevered piezoelectric nanogenerator having high ‎output power through vibrational energy harvesting that is simulated using finite element ‎method (FEM). The simulations are done for three types of perovskite piezoelectric ‎materials including PZT, PMN-PT and MAPbI3. The interdigitated electrodes were ‎exploited‏ ‏to obtain longitudinal vibration mode using d33 mode of piezoelectric layer during ‎the bending of nanogenerator structure. The presented structure consists of a piezoelectric ‎nanolayer with gold interdigitated electrodes on it, which is placed on a flexible PET ‎polymeric substrate. To encapsulate the piezoelectric layer, an SU-8 epoxy is placed over ‎the surface. The poling process is also simulated by applying high voltage through IDs to ‎piezoelectric layer. Generally, the electric potential distribution of the piezoelectric layer ‎must be performed by applying mechanical loadings. Then the output voltage, ‎power for free vibrations and base excitation (0.25-2g) of the nanogenerator at resonance ‎frequency are investigated. The resonance frequency of the PZT, PMN-PT, and MAPbI3 were ‎calculated to be 549 Hz, 560.5 Hz and 631 Hz, respectively. We found that PZT ‎piezoelectric materials yields maximum output voltage and electrical power values of 91.69 ‎V and 350 mW which shows better performance in vibrational energy harvesting ‎application. In comparison, the results of the simulation implied a good agreement with ‎other experimental studies. The unimorph piezoelectric energy harvester system generates ‎high voltage and output power in response to sub-kilohertz ambient vibration‎.‎‎

Fabrication and testing of Mg2Si1-xSnx based thermoelectric generator module

Mg2Si1-xSnx solid solutions have been of great interest for the advantages they hold as prospective thermoelectric (TE) materials. Despite this, the development of thermoelectric generator (TEG) modules fabricated entirely from these materials has not been reported. In this work, a TEG module consisting of Mg2Si0.3Sn0.7n and p legs has been fabricated, and its thermoelectric generator characteristics were studied as a function of the applied temperature gradient. For the n and p doped legs, compositions with peak zT values of ~1.6 and ~0.44, respectively, were synthesized using induction assisted melt synthesis. Mono-block sintering technique was adopted as a single-step compaction cum contacting technique. In order to create low resistive well-bonded contacts, an additional interfacial layer was placed between the TE material and the outer Cu layer. The TE legs were assembled into a skeletal module comprising of two unicouples electrically connected by Cu bridges. The transient state I-V characteristics of the TE device were measured at various temperature gradients (ΔT). A maximum power output value of 192mW (corresponds to a power density of 0.52 W/cm2) and open-circuit voltage of 200 mV were measured for a ΔT of 331 K. The measured I-V and power output data showed good agreement with the simulated power output values with a variation of only 3% until ΔT = 300 K and 5% at ΔT = 331 K. The TE module simulator was further used to estimate the device efficiency (η) and indicated a maximum value of 5%. This is the highest reported conversion efficiency of a silicide based module (in the studied temperature range) and highlights the possibility of their commercialization in the near future.

Desain Rangkaian Gate Driver Analog untuk Dual Mosfet Drivers

Switching techniques have been continued to develop, including sinusoidal PWM, space vector PWM, current tracking PWM, harmonic elimination PWM and others. Each method has advantages and disadvantages, but the most commonly used methods are sinusoidal PWM and space vector PWM. PWM that is generated using a microcontroller or analog IC component generally has a maximum voltage value of 5V. To strengthen the PWM wave, a gate-driver circuit is needed, so that the PWM control wave is able to move the IGBT / MOSFET. On this paper, the design of gate driver circuit use An analog IC, which starts from the generation of two waves, namely a sinusoidal wave and a DC source to be compared (Comparator) so that it can produce a PWM wave. Then this PWM wave is isolated using an optocoupler and MOSFET driver IC to limit interference in the switching process on high power supplies. Based on the results, it can be cancluded PWM control wave output from the gate-driver circuit is isolated from the system intended for designing a power converter and other applications.