Hasil untuk "Applications of electric power"

Qian Wang, Chenxu Wang, Wei-Hong Zhong

Batteries are a cornerstone of modern technology that supports a wide range of applications including portable electronics, electric vehicles and large-scale energy storage for renewable power systems. Despite their widespread use, commercial Li-ion batteries are limited by the mineral resources of Li. The rapidly growing battery market demands alternative battery systems, such as non-alkali metal-ion batteries, that are capable of delivering comparative energy densities. In the meantime, improving the performance of the batteries via generating sustainable strategies has been broadly studied. Proteins, as re naturally evolved macromolecules that possess diverse structures and functional groups, have been demonstrated to be able to transport various metallic ions inside bio-organisms. Therefore, active studies have been carried out on the use of natural proteins (e.g., zein, soy, fibroin, bovine serum albumin, etc.) to enhance the electrochemical performance of non-alkali metal-ion batteries. This review provides a comprehensive summary of recent advances on the studies of protein-based strategies for non-alkali metal-ion batteries and outlines perspectives for future sustainable electrochemical energy storage systems.

Yangfan Liu, Qixiao Li, Zhongxuan Wang

Bipolar power supply can effectively reduce line losses and optimize power transmission. This paper proposes a low-power bipolar DC–DC converter with voltage self-balancing, which not only achieves bipolar output but also automatically balances the inter-pole voltage under load imbalance conditions without requiring additional voltage balancing control. This paper first elaborates on the derivation process of the proposed converter, then analyzes its working principles and performance characteristics. A 400 W experimental prototype is built to validate the correctness of the theoretical analysis and the voltage self-balancing capability. Finally, loss analysis and conclusions are presented.

FANG Xinyu, XIA Donghui, HUANG Mei et al.

ObjectivesCollective Thomson scattering (CTS) is one of the few fusion diagnostic technologies that can provide fast ion kinetic property measurement in the center of fusion devices. However, the physical models that CTS diagnosis relies on at home and abroad currently have problems such as lack of electromagnetic effects and inaccurate plasma dielectric properties, which hinders the development of CTS diagnostic theory. Therefore, it is urgent to develop a more comprehensive CTS physical model code to support the development of CTS diagnosis.MethodsThe establishment and derivation of the full electromagnetic model is introduced, and the similarities and differences between the full electromagnetic model and the electrostatic model are analysed. The spectrum characteristics of the full electromagnetic model CTS under different parameters are studied based on the HL-2A device.ResultsThe full electromagnetic model is consistent with the electrostatic model results in conventional diagnosis. In addition, the full electromagnetic model has obvious advantages in diagnosing structures such as ion-Bernstein waves. The full electromagnetic model is used to optimize the system parameters for the CTS system of the HL-2A device.ConclusionsIn CTS spectrum research, the full electromagnetic model has more complete functions and huge potential, and can provide a powerful tool for CTS diagnosis of physical quantities such as ion ratios. In the future, based on more devices at home and abroad, the full electromagnetic model will have broader application prospects.

KE Minghui, LAI Lin

In order to explore the influencing factors and laws of the basic process of electrogasdynamic power generation, a simple electrogasdaynamic high-voltage power generation test device with exposed electrode structure was designed based on the basic theory of electrogasdaynamic power generation. Based on this device, high-pressure air was used as the working medium, high-speed airflow was generated through sonic nozzles, and charged particles were generated by corona discharge at the exposed needle electrode. The influences of structural and electrical parameters such as total gas pressure, conversion section length, load resistance, applied voltage, and circuit connection on the voltage and power of electrogasdynamic power generation were studied. By reasonably configuring the parameters of the power generation device, a collection voltage of 4.41 times the corona voltage or a collection power of 3.53 times the corona power was obtained. The research shows that the electric potential is parabolically distributed along the conversion section. The greater the load resistance, the higher the collection voltage. As the applied voltage increases, the larger the collection power, the smaller the ratio of the collection power to the corona power.

Adrián González-Parada, Francisco Moreno Del Valle, Ricard Bosch-Tous

In the transportation industry, the use of renewable energies has been implemented in conjunction with the development of higher-power electric motors and, consequently, the development of intelligent control systems for torque and speed control. Currently, the coupling between both systems is being developed through mechanical systems, affecting the efficient transmission of energy and the useful life of the components. On the other hand, new configurations of electric motors are being developed, such as axial flux motors (AFM), because these can be coupled directly without a mechanical coupling, given their characteristics of high torque at low speeds. In the present work, an innovative design of a multipole axial flux motor (MAFM) is introduced. General criteria for the design and construction are presented considering the geometry in axial flux and permanent magnets. The performance of the system is evaluated through finite element magnetic simulations (FEMM) and compared with experimental measurements of the developed prototype; confirming the effectiveness of the design, obtaining torques of up to 1.784 Nm without extra mechanical couplings and maximum speed regulation errors of 8.43%. The motor was controlled by a digital pole switching system whit six control mode, applied to a permanent magnet MFA for speed and torque control at constant speed. This control can be extended to conventional radial flux electric motor configurations and intelligent traction applications, based on torque demand.

Mohamed Y. Metwly, Charles L. Clark, Jiangbiao He et al.

The employment of robots in numerous emerging applications, e.g., disaster rescue, nuclear waste remediation, and space exploration, is of paramount importance due to their improved safety, flexibility, and productivity. Due to the harsh environmental conditions, the robotic arm joint motors and power electronic drives are vulnerable to electrical faults and mainly contribute to joint failures. To substantially improve the reliability and robustness of the robot arms utilized in remote, hazardous, and safety-critical environments, autonomous fault-tolerant and fail-active operation for these robotic arms experiencing joint failures should be developed. In the literature, many strategies have been proposed for fault prognosis, diagnosis, and health monitoring of electric motors and drives using online data analytics of the fault signature information. Thus, this paper presents an extensive up-to-date review of joint motor types, common fault types, and robot joint fault prognostics, diagnostics, and health management. First, various joint motors are introduced and compared, considering their performance advantages, disadvantages, and wide applications. Furthermore, joint motors for collaborative robotic applications are summarized and compared as illustrative examples. After that, fault types are reviewed with a further classification by fault locations, namely, stator windings, rotors, and bearings. In addition, health monitoring techniques are classified into methods for stator winding, rotor, and bearing faults. These methods are intensively compared with respect to motor and fault types, proposed health monitoring techniques, and control strategies. Finally, conclusions and future research trends are summarized.

CHEN Jian, TANG Zhiyuan, QIAO Ao et al.

Under the 'dual-carbon' goal, industrial parks, as the most important and extensive carriers of industrial systems, must undergo low-carbon transformation. In this context, this paper establishes a bi-level optimal dispatching model of low-carbon industrial park considering flexible scheduling of high-energy-consuming enterprises' production workshops. The model fully exploits the flexible adjustment ability of high-energy-consuming enterprises, obtains the optimal low-carbon scheduling plan of the park by flexibly adjusting the production scheme of high-energy-consuming enterprises to realize the coordinated operation of the industrial park and high-energy-consuming enterprises. Firstly, the upper layer establishes an optimal scheduling model with the objective of minimizing the total operating cost, taking into account carbon trading and tradable green certificate costs. Then, the lower layer focuses on the flexible scheduling problem of the high-energy-consuming enterprise's production workshops within the industrial park, aiming to minimize the maximum completion time and cost. The cost savings achieved by enterprise scheduling at the operational layer are used as subsidies. The upper and lower layers continuously coordinate and schedule plans to achieve the optimal objective. Finally, the feasibility and effectiveness of the proposed model are verified through case studies. The proposed approach not only reduces production costs and improves production efficiency but also effectively promotes load balancing, realizing the low-carbon operation of the industrial park.

Xueqing Zhang, Fengwu Bai, Xuesong Zhang et al.

Planar light concentrators are potential applications for solar thermal conversion, in which the intensity of the electric field will exhibit strongly non-uniform characteristics. However, previous research has long ignored the solar absorption performance of plasmonic nanoparticles in the focused electric field. In this work, we use the finite element method (FEM) to study the optical behaviors of a single nanoparticle and multiple nanoparticles in the focused electric field formed by vertically and inwardly imposing the initial incident light on a quarter cylindrical surface. The results show that the focused electric field can significantly improve the solar absorption abilities compared with the parallel one for all the nanoparticles due to the local near-electric field enhancement caused by the aggregation of the free electrons on the smaller zone. Further studies on the focused electric field reveal that the plasmon heating behavior of Au spheres presents a rising trend with the decrease in inter-particle spacing, as the gap is less than the radius of Au spheres. As the number of nanoparticles increases along the focal line, the absorption power of the center nanoparticles gradually tends to be stable, and it is much lower than that of a single nanoparticle. As the nanoparticles are arranged along the <i>y</i> and <i>z</i> directions, the heterogeneity of the electric field makes the optical properties uneven. Notably, the strongest electric field appears slightly close to the incident surface rather than on the focal line.

Pedro L.O. Machado, Thomas S. Pereira, Marcio G. Trindade et al.

The overheating of electronic devices has become very common with the advancement of technology, requiring the development of new alternatives for thermal control. Due to their excellent heat transfer ability, no external power is needed and they are adaptable to different geometries and applications. Thermosyphons are an excellent alternative for this thermal control. The thermal performance of thermosyphons is usually evaluated by their thermal resistance, and several variables were investigated to understand their influence on this parameter, such as working fluid, filling ratio, and slope. In that way, the fact that the thermal resistance depends on several variables makes its prediction complex and time-consuming. To overcome this issue, artificial intelligence-based methods, such as Artificial Neural Networks (ANNs), could be used. In this sense, an experimental investigation of the thermal performance of thermosyphon under different filling ratios (20 to 100%), slopes (45 and 90°), and heat loads (5 to 45 W) was made. The experimental data were then used as the database for different ANNs to predict the thermal resistance of a thermosyphon. For the experimental investigation, a thermosyphon of copper tube was built of 9.45 mm and 7.75 mm outer and inner diameter and a length of 500 mm. Its regions, evaporator, adiabatic section, and condenser, had 80, 20, and 100 mm, respectively. Distilled water was used as the working fluid. The evaporator was heated due to the Joule’s effect resulting from power dissipation in an electric ribbon wrapped in its length. The condenser was cooled with a 5 m/s air-forced convection. Regarding the use of ANNs, Unorganized Machines (UMs), composed of Extreme Learning Machines (ELM) and Echo State Networks (ESN), were proposed. As a means of comparison, the Radial Basis Function Network, and the Multilayer Perceptron (MLP), the most widely known neural architecture in the literature, were also applied. To estimate the thermal resistance of thermosyphon, the filling ratio, slope, and heat load were considered as inputs, and a total of 67 samples were used. Experimental results indicated that the best thermal performance occurs at a filling ratio of 40%, while the slope of 45° presented a better performance than 90°. The computational results revealed that the UMs could overcome the other methods, especially the ESN. The difference between the predicted and the experimental values was up to 25% for almost all cases. As a matter of reducing the experimental tests, applying ANN was essential.

Emiliano Pipitone, Salvatore Caltabellotta, Antonino Sferlazza et al.

The efficiency of hybrid electric vehicles may be substantially increased if the energy of exhaust gases, which do not complete the expansion inside the cylinder of the internal combustion engine, is efficiently recovered using a properly designed turbo-generator and employed for vehicle propulsion. Previous studies, carried out by the same authors of this work, showed a potential hybrid vehicle fuel efficiency increment up to 15% employing a 20 kW turbine on a 100 HP-rated power thermal unit. The innovative thermal unit proposed here is composed of a supercharged engine endowed with a properly designed turbo-generator, which comprises two fundamental elements: an exhaust gas turbine expressly designed and optimized for the application, and a suitable electric generator necessary to convert the recovered energy into electric energy, which can be stored in the on-board energy storage system of the vehicle. In this two-part work, the realistic efficiency of the innovative thermal unit for hybrid vehicles is evaluated and compared to a traditional turbocharged engine. In Part 1, the authors presented a model for the prediction of the efficiency of a dedicated radial turbine, based on a simple but effective mean-line approach; the same paper also reports a design algorithm, which, thanks to some assumptions and approximations, allows fast determination of the right turbine geometry for a given design operating condition. It is worth pointing out that, being optimized for quasi-steady power production, the exhaust gas turbine here considered is quite different from the ones commonly employed for turbocharging applications; for this reason, and in consideration of the required power size, such a turbine is not available on the market, nor has its development been previously carried out in the scientific literature. In this paper, Part 2, a radial turbine geometry is defined for the thermal unit previously calculated, employing the design algorithm described in Part 1; the realistic energetic advantages that could be achieved by the implementation of the turbo-generator on a hybrid propulsion system are evaluated through the performance prediction model under different operating conditions of the thermal unit. As an overall result, it was estimated that, compared to a reference traditional turbocharged engine, the turbo-compound system could gain vehicle efficiency improvement between 3.1% and 17.9%, according to the output power delivered, with an average efficiency increment of 10.9% evaluated on the whole operating range.

Tanmay Shukla, Narayan Prasad Patidar, Apsara Adhikari

This article presents a power factor profile-improved bridgeless buckboost-Cuk converter-fed battery charging system for electric vehicle applications. The conventional charging system does not use any power factor improvement stage, due to which the supply current harmonics are very high and violate IEC-61000-3-2 standard guidelines. To meet the international standard guidelines, a compact and efficient power factor-improved converter stage is necessary. The power factor-improved converter in the present work uses a fourth-order Cuk converter during negative semi-cycle and a second-order buckboost converter during positive semi-cycles of the supply voltage. The amalgamation of a second- and fourth-order converter in a bridgeless configuration reduces the system’s order concerning a bridgeless Cuk converter-based system and also eradicates the need for a diode-based bridge rectifier (DbBR). Due to the presence of an input side inductor, there is no requirement for an external filter like a bridgeless buckboost converter-based scheme. The input inductor in the present scheme performs twin action; it reduces harmonic disturbances in the mains current during the negative semi-cycle and also works with capacitor CP to filter harmonics and improve the mains current profile during the positive semi-cycle of the mains voltage. The power factor-improved converter in the present work is operated in discontinuous conduction mode (DCM). This eliminates the requirement for extra sensors compared to continuous conduction mode (CCM). The scheme also eliminates the need for two extra back-feed diodes which are generally required in bridgeless configuration loop completion during different semi-cycles of mains voltage. In the present scheme, the work of back-feed diodes is done by the anti-parallel inherent diodes of the switches. In the second stage, a high-frequency-operated flyback converter is used which not only boosts the battery current profile but also provides the electrical isolation between the supply side and load. This article also presents the detailed stability analysis and math modeling of the presented bridgeless buckboost-Cuk converter. The presented system is built on MATLAB/Simulink, and results are presented and discussed to validate the system performance.

Zezhao Wen, Hongye Zhang, Markus Mueller

The development of superconducting technology has seen continuously increasing interest, especially in the area of clean power systems and electrification of transport with low CO₂ emission. Electric machines, as the major producer and consumer of the global electrical energy, have played a critical role in achieving zero carbon emission. The superior current carrying capacity of superconductors with zero DC loss opens the way to the next-generation electric machines characterized by much higher efficiency and power density compared to conventional machines. The persistent current mode is the optimal working condition for a superconducting magnet, and thus the energization of superconducting field windings has become a crucial challenge to be tackled, to which high temperature superconducting (HTS) flux pumps have been proposed as a promising solution. An HTS flux pump enables current injection into a closed superconducting coil wirelessly and provides continuous compensation to offset current decay, avoiding excessive cryogenic losses and sophisticated power electronics facilities. Despite many publications regarding the design and analyses of various types of HTS flux pumps, the practical application of HTS flux pumps in a high-performance superconducting machine has been rarely reported. Therefore, it is of significance to specify the main challenges for building and implementing a reliable HTS flux pump. In addition, the physical mechanisms of distinct HTS flux pumps have caused some confusion, which should be clarified. Above all, a systematic review of the recent development and progress of HTS flux pumps remains lacking. Given the above-mentioned issues, this paper summarized the most up-to-date advances of this emerging technology, clarified the working mechanisms and commonly adopted modeling approaches, presented objective analyses of the applicability of various HTS flux pumps, specified the primary challenges for implementing HTS flux pumps, and proposed useful suggestions to improve this wireless excitation technology. The overall aim of this work is to bring a deep insight into the understanding of HTS flux pumps and provide comprehensive guidance for their future research and applications.

Martin Jeannerot, Morvan Ouisse, Vincent Lanfranchi et al.

Abstract This study presents a sensitivity analysis methodology used for electric motor design. This innovative approach evaluates both global effects of parameter variations in their design range and of parameter deviations in their tolerance intervals on design objectives. For the purpose of robust optimisation, this method helps to select the most influent design parameters and uncertain parameters, which are not necessarily the same. Suitable for any design approach, this method is particularly useful in dealing with objectives defined by non‐linear and non‐regular functions, such as electric motor acoustic criteria. In this study, the method is applied to the sensitivity evaluation of electromagnetic tangential excitations responsible for acoustic emissions in an electric motor. The sensitivity of output mean torque is also investigated. The sensitivity analysis shows that acoustic criteria appear generally more sensitive to parameter deviations than mean torque. Parameter deviations can be even more influent on acoustic criteria than larger parameter variations in their design range. As can be expected from the sensitivity results, the study eventually shows that the acoustic optimisation of the electric motor faces robustness issues.

H. Zhang, D. T. Li, F. He et al.

There is a large number of missions that have been or will be launched soon that utilize the electric propulsion (EP), which is considered a key technology for applications in present and future space missions. Accomplishing an accurate measure of the thrust is a key aspect of the laboratory verification of EP systems. In the case of ground conditions and direct measurements, it is complicated to verify the thrusters, especially for some high power (>5 kW) thrusters. For this reason, we have developed an indirect method for measuring thrust. We have carried out an experiment with a Hall effect thruster (operated in the 250 W power range) and compared results against direct thrust measurements. The difficulties in the indirect measurement are analyzed, which provides a basis for the development of indirect thrust measurement.

Jiuhe WANG, Mian WANG, Xuezhi WU et al.

In practical engineering application, it is necessary to judge the stability of direct current distributed power system (DCDPS) by using stability criteria, so as to adopt appropriate control strategies. Therefore, stability criteria of DCDPS are generally interested by scholars at home and abroad. The basic idea and characteristics of stability criteria based on equivalent source converter (subsystem) and equivalent load converter (subsystem), a bus voltage-controlled converter and a bus current-controlled converter, passivity and large disturbance signal were analyzed. Based on the above analysis, the advantages and defects of the stability criteria were pointed out. The research trends of the stability criteria for DCDPS were put forward, and a new method of stability criteria was proposed by combining passivity-based stability criterion and other stability criteria.

R. HENDI, H. SAIFI, K. BELMOKRE et al.

The impact of the black clay soil moisture of Skikda (East of Algeria), on the corrosion cathodic protection performance of the API X70 pipeline was studied in this paper. To achieve this objective, first, electrochemical analysis has been carried out. Then, in order the show impact of the black clay soil moisture of Skikda on the cathodic protection of the API X70 Pipeline, the corrosion parameters of the API X70 steel pipeline obtained by electrochemical measurements such as Tafel slopes, corrosion current densities, and corrosion potentials were used as boundary conditions in the elaborated cathodic protection model. The obtained results show that the corrosion current I corr is directly proportional to the moisture content up to 50 wt. %, with a potential shift towards the more electronegative values. The cathodic protection perfermance has been well proven in black soil at 100 wt. % moisture contents.

Ali J. Al-Askery, Ali Al-Naji, Mohammed Sameer Alsabah

In this paper, the performance of coded systems is considered in the presence of Suzuki fading channels, which is a combination of both short-fading and long-fading channels. The problem in manipulating a Suzuki fading model is the complicated integration involved in the evaluation of the Suzuki probability density function (PDF). In this paper, we calculated noise PDF after the zero-forcing equalizer (ZFE) at the receiver end with several approaches. In addition, we used the derived PDF to calculate the log-likelihood ratios (LLRs) for turbo-coded systems, and results were compared to Gaussian distribution-based LLRs. The results showed a 2 dB improvement in performance compared to traditional LLRs at <inline-formula> <math display="inline"> <semantics> <msup> <mn>10</mn> <mrow> <mo>&#8722;</mo> <mn>6</mn> </mrow> </msup> </semantics> </math> </inline-formula> of the bit error rate (BER) with no added complexity. Simulations were obtained utilizing the Matlab program, and results showed good improvement in the performance of the turbo-coded system with the proposed LLRs compared to Gaussian-based LLRs.

Chuanling LIU, Minghui LIU, Zhenjiang CHEN et al.

After low pressure economizer was put into the unit, waste heat of boiler flue gas enters the regenerative system. The extraction steam returns to low pressure cylinder, and the steam volume increases, which causes the change of the back pressure of the steam turbine. According to the equivalent enthalpy drop theory, the calculation model of back pressure change was established. The model is verified through the test and analysis of one 220MW unit. Under 220MW working condition, the steam turbine back pressure is increased by 0.29 kPa. After the correction of the back pressure, the energy saving of "equivalent enthalpy drop method" decreases by 0.19%, which is closer to the energy saving of the "thermal test method". It shows that in the energy saving effect analysis of operating low-cost economizer with the "equivalent enthalpy drop method", the impact of back pressure changes on energy savings need to be considered.

Daniel Orfeo, Dylan Burns, Robert Farrell et al.

This study reports on the theory of operation, design principles, and results from laboratory and field tests of a magnetic telemetry system for communication with underground infrastructure sensors using rotating permanent magnets as the sources and compact magnetometers as the receivers. Many cities seek ways to monitor underground water pipes with centrally managed Internet of Things (IoT) systems. This requires the development of numerous reliable low-cost wireless sensors, such as moisture sensors and flow meters, which can transmit information from subterranean pipes to surface-mounted receivers. Traditional megahertz radio communication systems are often unable to penetrate through multiple feet of earthen and manmade materials and have impractically large energy requirements which preclude the use of long-life batteries, require complex (and expensive) built-in energy harvesting systems, or long leads that run antennas near to the surface. Low-power magnetic signaling systems do not suffer from this drawback: low-frequency electromagnetic waves readily penetrate through several feet of earth and water. Traditional magnetic telemetry systems that use energy-inefficient large induction coils and antennas as sources and receivers are not practical for underground IoT-type sensing applications. However, rotating a permanent magnet creates a completely reversing oscillating magnetic field. The recent proliferation of strong rare-earth permanent magnets and high-sensitivity magnetometers enables alternative magnetic telemetry system concepts with significantly more compact formats and lower energy consumption. The system used in this study represents a novel combination of megahertz radio and magnetic signaling techniques for the purposes of underground infrastructure monitoring. In this study, two subterranean infrastructure sensors exploit this phenomenon to transmit information to an aboveground radio-networked magnetometer receiver. A flow meter uses a propeller to directly rotate a diametrically magnetized neodymium magnet. A moisture sensor rotates a magnet with a low-power electric motor. Laboratory performance and field tests establish the capabilities of magnetic telemetry for IoT-linked leak-detection sensors. Remote datalogging with encryption demonstrates the viability of integrating sensors and surface receivers into a LoRa wireless IoT network.

Panca Mudji Raharjo, Mochammad Rif'an, Nanang Sulistyanto

This research is aimed to implement feedforward backpropagation algorithm for digit handwritten recognition in an FPGA, Xilinx Spartan 3. This research is expected to give a contribution such as the feedforward algorithm design in VLSI technology based on FPGA, the practice module of Xilinx Spartan-3 development board and further research in artificial neural network and FPGA field in Electronics Laboratory. The feedforward backpropagation algorithm is used to recognize 10 objects. The feedforward backpropagation network consists of two layers, 36 input unit which is the feature vector of object, 10 hidden neurons, and 10 output unit. The first layer activation function is tansig and second layer activation function is purelin. The multipliers use 18 bits. The proposed design fits into the smallest Xilinx FPGAs3. Index Terms—feedforward backpropagation network, digit handwritten recognition, FPGA, Spartan-3.