Electrical Output Characteristics Research Articles

Electric energy output characteristics of polyvinylidene fluoride piezoelectric transducer under pulse stress: A simplified model

Because of its excellent performance, polyvinylidene fluoride (PVDF) transducers are commonly used to convert pulse kinetic energy into electrical energy. To quantify the relationship between the transducer's input pulse stress and output electrical energy, this study established a voltage output model by simplifying the pulse stress into a triangular pulse. Then, the model's reliability was verified through three experiments, and the causes of model deviations were determined. Subsequently, the influence of the transducer (area A and piezoelectric constant K), pulse stress (pulse rise time t1 and loading rate F1), and circuit (load resistance Rm and PVDF capacitance CP) on energy conversion were analyzed with the model. Results show A, K, and F1 are directly proportional to the maximum output voltage Vmax. As Rm increases, Vmax increases and gradually approaches the limit value, AKF1t1/CP. When the peak stress remains constant, the influence of t1 on Vmax is opposite to that of Rm. When CP is larger than t1/10Rm, reducing CP leads to Vmax increases, and the increasing rate is maximized as CP approaches t1/2Rm. This study clarifies the influence of key parameters in the harvester on its energy output characteristics, which is helpful for its optimizing design in different applications.

Characteristic Study of a Typical Satellite Solar Panel under Mechanical Vibrations.

As the most common energy source of spacecraft, photovoltaic (PV) power generation has become one of the hottest research fields. During the on-orbit operation of spacecraft, the influence of various uncertain factors and the unbalanced inertial force will make the solar PV wing vibrate and degrade its performance. In this study, we investigated the influence of mechanical vibration on the output characteristics of PV array systems. Specifically, we focused on a three-segment solar panel commonly found on satellites, analyzing both its dynamic response and electrical output characteristics under mechanical vibration using numerical simulation software. The correctness of the simulation model was partly confirmed by experiments. The results showed that the maximum output power of the selected solar panel was reduced by 5.53% and its fill factor exhibited a decline from the original value of 0.8031 to 0.7587, provided that the external load applied on the panel increased to 10 N/m2, i.e., the vibration frequency and the maximal deflection angle were 0.3754 Hz and 74.9871°, respectively. These findings highlight a significant decrease in the overall energy conversion efficiency of the solar panel when operating under vibration conditions.

Performance evaluation of coloured filters on PV panels in an outdoor environment

AbstractThis study aims to investigate the effects of colour filters and tilt angles on the electrical output characteristics of solar photovoltaic modules. The experimental set‐up allowed for the evaluation of various combinations of colour filters and tilt angles by using a realistic simulation of solar panel installations. The various light spectrum wavelengths and energy levels were taken into account, keeping in mind any potential impacts on the solar cells' conversion efficiency. The results showed that compared to other filter combinations, the use of red colour filters with a 10% blockage rate and an optimal tilt angle led to a noticeable increase in electrical output. This result emphasises the value of colour filtering and tilt angle selection in raising solar photovoltaic systems' overall performance. When compared to the other filters, the red, orange, and yellow filters stand out due to their outstanding efficiency of around 84.98%, 84.08%, and 83.69%. However, the teal, green, and blue filters exhibit relatively low levels of efficiency of about 69.62%, 67.06%, and 58.52%, respectively. The distinct reaction shown by purple and pink filters, when subjected to tilt angle of 30 degrees, offers a potentially productive direction of enhancing the efficiency of PV panel.

Optimizing PV Module Efficiency: Investigating the impact of Dry and Wet Dust on Solar Panel Output Power

Solar photovoltaic modules convert sunlight into electricity through the photoelectric effect. Dust accumulation on PV modules can significantly reduce their output electrical characteristics such as voltage, current, and power. The power reduction is attributed to the decrease in the amount of light reaching the solar cells due to the absorption and scattering of light by the dust layer. The magnitude of the power reduction depends on the amount and type of dust component of the solar panel. In this work, four dust components such as red soil, sand, wood power, and bird drooping are considered to test the PV performance. An indoor experimental setup is developed to test the dust impact on the PV modules using an artificial sun simulator. Experimental shows that the effect of dust accumulation on the voltage and current characteristics of solar panels is complex and depends on various factors. The percentage of degradation of output power is measured using dust under dry and wet conditions. Moreover, different amounts of dust such as 1gm, 3gm, 5gm, 7gm, and 9gm are considered for dry conditions, and 3gm and 5gm are considered for wet conditions. Bird drop causes a maximum degradation of 24.5% in dry conditions and it reduces by 17.2% in wet conditions. GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 10(1), 2023 P 68-74

Ultra-stretchable and high performance fibrous TENG with helically structured dual-channel Liquid Metal electrode

Fibrous triboelectric nanogenerators (FTENGs) are highly desirable nano-energy harvesting devices due to largely available contact area and convenience in integration, which enables more efficient conversion of randomly disordered low-mass mechanical energy into electrical energy. Unfortunately, the high triboelectric output of existing FTENGs under mechanical deformations is considerably limited due to their inherently low stretchability of conductive or friction materials. Therefore, simplified equivalent models are established by mimicking the core–shell structure of natural silk, which discuss the influence of different structural variables of fibers on the electrical energy output, thus guiding the design of construction as well as enhancing the triboelectric behaviors. Herein, we successfully constructed a dual-structure variable FTENG (DF) (dual-channel electrode, twisting) that combines excellent stretch and electric performance by utilizing an efficient and scalable thermal stretching, twisting, and injection process. The twisting process assigns the FTENG a larger effective contact area to enhance the surface charge density of the friction material, while the dual-channel electrode enable faster charge transfer, resulting in a significant improvement in the triboelectric output performance. The open-circuit voltage (Voc) of the DF is up to 265.8 V/m, far surpassing the non-structure variable, single electrode-structure variable and single twisting-structure variable counterpart FTENGs, providing remarkable durability. Also, a single DF has a strain at break of up to 862.3 %, exhibiting excellent mechanical stretchability. Moreover, multiple DFs can achieve more significant electrical output characteristics. The dual-structure variable design and the facile manufacturing method will bring inspiration for the preparation of high-performance energy production devices.

Bacterial cellulose/multi-walled carbon nanotube composite films for moist-electric energy harvesting

Generation of renewable and clean electricity energy from ubiquitous moisture for the power supply of portable electronic devices has become one of the most promising energy collection methods. However, the modest electrical output and transient power supply characteristics of existing moist-electric generator (MEG) severely limit its commercial application, leading to an urgent demand of developing a MEG with high electrical output and continuous power generation capacity. In this work, it is demonstrated that a flexible bacterial cellulose (BC)/Multi-walled carbon nanotube (MWCNT) double-layer (BM-dl) film prepared by vacuum filtration can maintain the moisture concentration difference in the film MEG. Unlike previous studies on cellulose based MEG, BM-dl film has a heterogeneous structure, resulting in a maximum output power density of 0.163 μW/cm2, an extreme voltage of 0.84 V, and current of 2.21 μA at RH = 90 %. BM-dl MEG can generate a voltage of 0.55 V continuously for 45 h in a natural environment (RH = 63–77 %, T = 26–27 °C), which is in a leading level among existing reported cellulose-based MEGs. In summary, this study provides new ideas for innovative design of MEG, which is highly competitive in terms of energy supply for the Internet of Things and wearable devices.

Dual‐Float‐Based Triboelectric Nanogenerator for Low‐Frequency Wave Energy Harvesting

Electromagnetic induction generator is not the best choice for collecting low frequency wave energy, since waves have the characteristics of low frequency and variable amplitude. In contrast, triboelectric nanogenerator (TENG) has an absolute advantage in collecting low‐frequency mechanical energy. Based on this, a dual‐float‐based triboelectric nanogenerator (DF‐TENG) for harvesting low‐frequency wave energy is proposed in this article. In this device, the TENG is mounted in the lower float, and its slider component is connected to the upper float by a cable. On the one hand, the motion of the slider is consistent with the relative motion of the dual floats, which is easy to analyze; on the other hand, the TENG is located in the lower float, which avoids damage to the TENG caused by extreme sea conditions. The physical model of the device was established, and the motion characteristics, electrical output characteristics, and its influencing factors of TENG were analyzed using finite element simulation software. The numerical calculations were verified by experimental tests. The calculated results show that the optimal matching resistance of the system is 500 MΩ. The research work in this article provides a research basis and reference for the development and application of such wave energy devices.

Optimization of Neurons Number in Artificial Neural Network Model for Predicting the Power Production of PV Module

In this work, an Artificial Neural Network (ANN) with a backward-propagation technique was used to predict the power generation of the Photovoltaic (PV) module in weather conditions of Baghdad city-Iraq. Experiment tests were investigated in the summer of 2022. Three weather parameters, including: (solar radiation, ambient temperature, and wind speed), the output electrical characteristics of the PV module (voltage, current, power), and module temperature (were measured. Therefore, the dataset of the ANN system consists of four input and one output parameter. Furthermore, the structure of ANN includes a single hidden layer with a backward propagation technique. The main goal of this study was to optimize the number of neurons in the training process. The evaluation of the ANN model depended on the determination coefficient (R) and Root Mean Squared Error (RMSE). The obtained results show that the architecture of ANN is appropriate for predicting the power generated from the PV module. The developed ANN model has good accuracy. Where the MSE is 0.002747 at epoch 9 in the model. Furthermore, the R is recorded as 0.99078, 0.98254, 0.99125, and 0.99005 for training, testing, validation, and all respectively in the proposed model. In addition, the optimization number of neurons in the hidden layer gave sufficient accuracy without referring to the choice of the number of neurons by using the trial-and-error method that most researchers relied.

Experimental investigation of using the evaporative air cooling technique to enhance the performance of the photovoltaic module

Abstract In this experimental study, two techniques of photovoltaic thermal (PVT) collector with active cooling were used to enhance the performance of the photovoltaic (PV) module. The first technique was prepared by integrating the PV module with a forced air duct (PVTFC). At the same time, the second technique was the PV module integrated with a forced air duct including a direct evaporative cooling unit (PVTDEC). In these two techniques, the air was forced by an electrical centrifugal fan with variable speeds (1.5, 2.5 and 3.5 m/s) placed at the end of the duct. The output electrical characteristics of the PVTFC and PVTDEC modules were compared with the reference PV module. The obtained results showed a significant decrease in the temperature of the PV module, where the reduction in the temperature of the PV module was achieved between 5°C and 16°C and 21°C and 25°C in PVTFC and PVTDEC techniques, respectively. Accordingly, the voltage was dropped to 15.1 and 15.8 V in PVTFC and PVTDEC, respectively, as compared with the sharp decline of voltage for the reference PV module, which recorded 14.2 V at a maximum PV module temperature of 69°C. In addition, the maximum enhancement percentage of PV efficiency was achieved at a maximum airflow rate of 0.22 kg/s, where it was recorded between 3.5% and 6.2% in the case of PVTFC and 7% and 9.3% in the case of PVTDEC.

Equivalent circuit models for predicting electrical and gas output characteristics of CO2 electrolysis cells

An equivalent circuit model for a CO2 electrolysis cell producing CO and H2 is proposed, taking into account that the CO2 input and the transfer of both carbonate and hydrogen carbonate ions limit the CO partial current density.

A durable non-contact reciprocated triboelectric nanogenerator for low-frequency vibration energy harvesting

Harvesting vibration energy using a triboelectric nanogenerator (TENG) is a promising approach in solving the power supply restriction of the Internet of Things. Currently, the low durability due to friction surface wearing is the primary limitation of TENGs, which restricts their applicability and practicability. This study introduces a non-contact-type TENG aimed at significantly enhancing its durability by increasing its anti-wear capability. The configuration of the proposed TENG includes permanent magnets and rolling-balls. The reciprocating motion of functional friction surfaces, facilitated by the permanent magnets, enhances the efficiency of harvesting low-frequency vibration energy. The embedded rolling-balls are utilized to separate two functional friction surfaces, which minimizes the friction surface wearing between different dielectric materials. The electrical output characteristics of this non-contact TENG under variable load resistances are explored according to sinusoidal excitation based on either variable frequencies or accelerations. The results demonstrate that the proposed nanogenerator can generate a short-circuit current of 2118.2 nA and achieve a peak power density of 9.891 mW/m2. The electrical responses of this non-contact TENG remain stable over 120 000 continuous working cycles, lasting for more than 200 min. Furthermore, the nanogenerator can identify and harvest energy from running or jumping motions performed by individuals in different postures and at various speeds or heights. With its exceptional durability and stability, this non-contact nanogenerator offers a novel approach to low-frequency vibration energy harvesting, paving the way for practical applications in the field.

Analysis of SiC/Si Heterojunction Band Energy and Interface State Characteristics for SiC/Si VDMOS.

SiC/Si and GaN/Si heterojunction technology has been widely used in power semiconductor devices, and SiC/Si VDMOS and GaN/Si VDMOS were proposed in our previous paper. Based on existing research, breakdown point transfer technology (BPT) was used to optimize SiC/Si VDMOS. Simulation results showed that the BV of the SiC/Si heterojunction VDMOS was considerably increased from 259 V to 1144 V, and Ron,sp decreased from 18.2 mΩ·cm2 to 6.03 mΩ·cm2 compared with Si VDMOS. In order to analyze the characteristics of the SiC/Si heterojunction structure deeply, the influence of the interface state characteristics of the SiC/Si heterojunction on the electrical parameters of VDMOS was analyzed, including electric field characteristics, blocking characteristics, output characteristics, and transfer characteristics. In addition, the influence of the interface state of the SiC/Si heterojunction on energy band characteristics was analyzed. The results showed that with an increase in the interfacial charge (acceptor) concentration, the p-type trap layer was introduced into the interface of the SiC/Si heterojunction, energy increased slightly, and the barrier height difference at the heterojunction increased, resulting in an increase in BV. At the same time, since the barrier height became higher, electrons did not flow easily, so Ron,sp increased. On the contrary, when a charge (donor) was introduced at the interface of the SiC/Si heterojunction, the number of electrons in the channel increased, resulting in an increase in the electron current, which is conducive to the flow of electrons, resulting in a decrease in Ron,sp. The energy band and other characteristics of devices with temperature were simulated at different temperatures. Finally, the effects of SiC/Si heterojunction interface states on interface capacitances and switching performances of VDMOS devices were also discussed.

Degumming effects of silk fabrics as piezoelectrics for nanogenerators

This study evaluated the suitability of silk fabric as a piezoelectric nanogenerator (PENG). A PENG with excellent mechanical and electrical properties as well as biocompatibility was fabricated using silk. Silk fibers are composed of sericin and fibroin, and effect of sericin on the piezoelectric properties was evaluated. X-ray diffraction, Raman spectroscopy, and Fourier transform infrared analyses showed that the presence of sericin reduced the piezoelectricity, and its removal (degumming) improved the electrical output characteristics of the specimens. The device output performance exhibited a positive dependence on pressure conditions, such as the load and pushing frequency. The generators prepared from specimens before and after degumming showed power densities of 0.43 and 1.52 μW/cm2, respectively, at an applied stress of 110 N. The electrical properties of the fabricated silk PENG were stable even after 10,000 cycles. Silk-fabric PENGs can be fabricated as low-cost, high-output devices without additional processes, such as electrospinning or coating, and they show significant potential for application in biosensors, medical sensors, and implantable medical devices.

An in-plane omnidirectional flutter piezoelectric wind energy harvester

Most wind energy harvesters that are based on wind-induced vibrations can only operate in a specific wind direction, which limits their application in environments with time-varying wind directions. Previously reported in-plane omnidirectional piezoelectric wind energy harvesters (PWEHs) based on vortex-induced vibrations can produce stable electrical output characteristics when the wind direction changes, but their output powers are relatively low and the working wind speed ranges are relatively narrow. To solve this issue, this work presents an in-plane omnidirectional flutter PWEH which is mainly composed of the bluff body of a hollow cylindrical shell and the inside elastic supporting structure of several piezoelectric composite beams. Finite element analysis shows that harvesters with both four and six supporting beams offer good stiffness and electromechanical conversion isotropies. Experiments demonstrate that both prototype devices are flutter PWEHs with rotation axes located on the rear of the geometrical center of the bluff body. The effect of wind speed on their directionality is small, and both prototypes show in-plane omnidirectional operation over a wide wind speed range, over which the electrical outputs remain relatively high. The prototype with six beams is preferred from the viewpoint of the wind direction adaptability. The onset wind speeds in different directions all range between 5.8 and 6.0 m/s, showing the good isotropy. The minimum and maximum powers are approximately 266.4 and 300.1 μW, respectively, at 10 m/s, and it shows in-plane omnidirectional energy harvesting performance in the wind speed range from 6.5 m/s up to more than 10 m/s.

Research on the Control Strategy of Urban Integrated Energy Systems Containing the Fuel Cell

As a new type of energy with the advantages of high efficiency, clean and pollution-free, fuel cells have attracted the attention of many experts and scholars. The efficient utilization of fuel cells will certainly become the mainstay of energy transformation and environmental protection. However, fuel cells have low power density, soft electrical output characteristics, and significantly delayed response to sudden load changes. When fuel cells are used as power supply energy alone, the output voltage fluctuates greatly, and the power supply reliability could be higher. To increase the fuel cell’s service life in real world applications, a DC converter and an appropriate auxiliary energy storage power supply are combined to form a fuel cell hybrid power supply system that makes efficient use of the auxiliary energy storage system’s availability, enhances the power supply system’s adaptability through dynamic reconfiguration, and provides better flexibility overall. This work proposes a method for managing the energy produced by an urban integrated power supply system that includes fuel cells, supercapacitors, and solar cells. Applying the IF-THEN rule of load power and the state of charge of the supercapacitors, the power balance is adjusted between the su-percapacitors, photovoltaic cells, and fuel cells according to the defined fuzzy logic control. The intermittent nature of solar power production and the erratic nature of fuel cell output may both be mitigated using this technique, allowing the load power to operate more reliably. The simulation results show that the control strategy adopted in this paper is able to not only meet the load requirements but also reasonably allocate the functional requirements and improve the working efficiency of the system, resulting in a clear optimization effect on the system’s control. In this paper, we focus on the fuel cell hybrid power supply system design, and then we use the idea of fuzzy logic control energy management to build the structure of the fuzzy logic control system, design the fuzzy controller, determine the functions, and verify the solutions through simulation and experimentation.

Assessing the impact of step gate oxide and gate electrode engineering on performance of β-Ga2O3 MOSFET for high frequency applications

In the present work, the advantages of step gate oxide and gate electrode engineering designs have been amalgamated with scaled β – Ga2O3 MOSFET for ultra-high frequency applications. Various device attributes such as channel potential, electric field distribution, output and transfer characteristics etc., have been studied using both analytical modeling and simulation approaches. Furthermore, the paper also explores numerous high frequency figure of merits such as cut-off frequency, gain bandwidth product and transconductance frequency product etc. Two-port parameters i.e., scattering parameters, Rollett's stability factor etc., and high-power metrics such as output power and power-added-efficiency etc., have also been investigated. The variation of device gain with frequency has also been studied. Furthermore, a thorough comparison is drawn between the proposed device, the device with only step gate oxide engineering and a uniform gate throughout, and the conventional device without any of these designs for fair assessment. It has been demonstrated that the proposed design is reliable and efficient with significant improvement in abovementioned figure of merits which makes it suitable contender for ultra-high frequency applications.

Structure optimization and performance of piezoelectric energy harvester for improving road power generation effect

This paper presents a cantilever piezoelectric energy harvester with excellent electrical output and mechanical characteristics for roads, which solves the problems of low electrical output level and low matching with road traffic of cantilever piezoelectric energy harvesters at present. Based on the finite element model, the structural characteristics of the energy harvester under different constraint forms are analyzed. The energy harvester structure is optimized according to the electrical output and stress distribution characteristics, and the size with high electrical output and good stress distribution is clarified. Finally, the good electrical effect of the proposed energy harvester structure and size is determined. The results indicate that the rigidly constrained energy harvester has higher potential and stress of the piezoelectric layer than the cantilever constrained, but the charge cancellation at both ends of the piezoelectric layer is obvious. Then the fixed end position and the displacement application position are considered to alleviate this phenomenon, and the former has obvious benefits in improving the electrical output effect and reducing the stress value. From the perspective of mechanics and electricity, the output voltage and output power of the energy harvester under the optimal size up to 24 V and 4.381 mW respectively, which are higher than other cantilever energy harvesters. The optimized energy harvester improves its electrical effect and mechanical characteristics under actual road traffic conditions, which lays a foundation for the cantilever piezoelectric energy harvester to collect road vibration energy.

Research on Output Characteristics of Microscale BST Laminate Structure Based on Mixed Finite Element Method

The flexoelectric effect, which is sensitive to size, refers to the phenomenon of coupling between the strain gradient and electrical polarization and involves higher-order derivatives of physical quantities such as displacement, and the analytical process is complicated and difficult. Therefore, in this paper, a mixed finite element method is developed considering the effects of size effect and flexoelectric effect on the electromechanical coupling behavior of microscale flexoelectric materials. Based on the theoretical model of enthalpy density and the modified couple stress theory, the theoretical model and finite element model of microscale flexoelectric effect are established, and the Lagrange multiplier is used to coordinate the higher-order derivative relationship between the displacement field and its gradient, and the C1 continuous quadrilateral 8-node (displacement and potential) and 4-node (displacement gradient and Lagrange multipliers) flexoelectric mixed element. By comparing the numerical calculation results and analytical solutions of the electrical output characteristics of the microscale BST/PDMS laminated cantilever structure, it is proved that the mixed finite element method designed in this paper is an effective tool for studying the electromechanical coupling behavior of flexoelectric materials.

Freestanding‐Mode Tribovoltaic Nanogenerator for Harvesting Sliding and Rotational Mechanical Energy

AbstractA series of direct‐current tribovoltaic nanogenerators (TVNGs) with high current density have been developed for energy harvesting and mechanical sensing recently, but the lead wires that need to be connected to two relatively moving parts have greatly restricted the application of TVNG. Herein, a freestanding‐mode TVNG (FTVNG) is proposed based on metal, p‐type silicon (p‐Si), and n‐type silicon (n‐Si). As the freestanding part of metal simultaneously rubs against p‐Si and n‐Si, opposite direct current (DC) outputs can be generated, thus forming a DC output from p‐Si to n‐Si in the external circuit. Resulting from the distinctive structure, FTVNGs are applicable for harvesting energy from moving objects without attached wires. Additionally, by using steel needles to precisely control the actual contact area, the electrical output characteristics and influence laws of the tribovoltaic effect under different working parameters such as area and speed are studied. Moreover, FTVNG is integrated into the traditional rolling bearing as a triboelectric bearing, realizing energy recovery from the rotational motion of mechanical parts and speed sensing, which demonstrates the great application potential of TVNG in basic components and parts.

Study on thermodynamic system characteristics of thermoelectric units under variable operating conditions

The variable working condition of thermal system refers to that the working condition in the system changes, deviates from the design working condition or deviates from a certain reference working condition. There are various reasons for the change of thermal system’s off design condition, including the change of unit heat load, the change of thermal system and equipment, and the change of steam parameters and reheat parameters. The purpose of variable condition calculation of thermodynamic system is to determine the steam parameters of each extraction port and exhaust end of the turbine and the corresponding parameters of the regenerative system. Its essence is to determine the new expansion process line and system parameters of the turbine. This is the basis for the safety and reliability analysis of the system under off design conditions and the calculation and analysis of economic indicators. Through the research on the electrothermal coupling characteristics of thermoelectric units under variable operating conditions, it can provide data support for the power grid dispatching department to master the electrical output characteristics of thermoelectric units in heating seasons.