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如何选择交流同步发电机组
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作者 王诞 《陕西农业》 2000年第6期21-21,共1页
苦所有用电负载都用单相电,则先择单相发电机组,其输出电压为220V/50Hz;若既有用单相电的负载,又有用三相电的负载或所有负载都用三相电,则选择三相发电机组,其输出电压为220V/50Hz和380C/50Hz。
关键词 交流同步发电机 选择 发电机数 功率
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上海世博行政中心光伏发电并网系统分析 被引量:2
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作者 张鹏飞 侯建华 《太阳能》 2008年第6期50-53,共4页
介绍了上海世博行政中心的光伏示范项目,数倍均匀聚光光伏发电机和非晶硅电池板的实际运用效果和产电量情况。
关键词 太阳能 倍均匀聚光光伏发电机 非晶硅电池板
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A Hybrid Random Number Generator Using Single Electron Tunneling Junctions and MOS Transistors
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作者 张万成 吴南健 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第4期693-700,共8页
This paper proposes a novel single electron random number generator (RNG). The generator consists of multiple tunneling junctions (MTJ) and a hybrid single electron transistor (SET)/MOS output circuit. It is an ... This paper proposes a novel single electron random number generator (RNG). The generator consists of multiple tunneling junctions (MTJ) and a hybrid single electron transistor (SET)/MOS output circuit. It is an oscillator-based RNG. MTJ is used to implement a high-frequency oscillator, which uses the inherent physical randomness in tunneling events of the MTJ to achieve large frequency drift. The hybrid SET and MOS output circuit is used to amplify and buffer the output signal of the MTJ oscillator. The RNG circuit generates high-quality random digital sequences with a simple structure. The operation speed of this circuit is as high as 1GHz. The circuit also has good driven capability and low power dissipation. This novel random number generator is a promising device for future cryptographic systems and communication applications. 展开更多
关键词 random number generator single electron transistor multiple tunneling junction OSCILLATOR
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Design of speed controller for electronic fuel injection gasoline generator based on feed-forward PID control
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作者 赵自庆 刘昌文 张平 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2015年第4期354-363,共10页
As for the application of electronic fuel injection (EFI) system to small gasoline generator set, mechanical speed controller cannot be coupled with EFI system and has the shortcomings of lagged regulation and poor ... As for the application of electronic fuel injection (EFI) system to small gasoline generator set, mechanical speed controller cannot be coupled with EFI system and has the shortcomings of lagged regulation and poor accuracy, a feed-forward control strategy based on load combined with proportional-integral-differential (PID) control strategy was proposed, and a digital speed controller applied to the electrical control system was designed. The detailed control strategy of the controller was intro- duced. The hardware design for the controller and the key circuits of motor driving, current sampling and angular signal captu- ring were given, and software architecture was discussed. Combined with a gasoline generator set mounted with EFI system, the controller parameters were tuned and optimized empirically by hardware in loop and bench test methods. Test results show that the speed deviation of generator set is low and the control system is stable in steady state; In transient state the control system responses quickly, has high stability under mutation loads especially when suddenly apply and remove 100% load, the speed deviation is within 8% of reference speed and the transient time is less than 5 s, satisfying the ISO standard. 展开更多
关键词 gasoline generator digital speed controller electronic fuel injection (EFI) feed forward proportional-integral-differential (PID) control
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Numerical Simulation of Wind Turbine Blade-Tower Interaction 被引量:15
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作者 Qiang Wang Hu Zhou Decheng Wan 《Journal of Marine Science and Application》 2012年第3期321-327,共7页
Numerical simulations of wind turbine blade-tower interaction by using the open source OpenFOAM tools coupled with arbitrary mesh interface (AMI) method were presented. The governing equations were the unsteady Reyn... Numerical simulations of wind turbine blade-tower interaction by using the open source OpenFOAM tools coupled with arbitrary mesh interface (AMI) method were presented. The governing equations were the unsteady Reynolds-averaged Navier-Stokes (RANS) which were solved by the pimpleDyMFoam solver, and the AMI method was employed to handle mesh movements. The National Renewable Energy Laboratory (NREL) phase VI wind turbine in upwind configuration was selected for numerical tests with different incoming wind speeds (5, 10, 15, and 25 m/s) at a fixed blade pitch and constant rotational speed. Detailed numerical results of vortex structure, time histories of thrust, and pressure distribution on the blade and tower were presented. The findings show that the wind turbine tower has little effect on the whole aerodynamic performance of an upwind wind turbine, while the rotating rotor will induce an obvious cyclic drop in the front pressure of the tower. Also, strong interaction of blade tip vortices with separation from the tower was observed. 展开更多
关键词 NREL phase VI wind turbine pimpleDyMFoam arbitrary mesh interface (AMI) blade-towerinteraction
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Study on dynamics of central pattern generator for a quadrupedal robot 被引量:1
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作者 张秀丽 Zheng Haojun 《High Technology Letters》 EI CAS 2007年第4期356-362,共7页
Based on Matsuoka's central pattern generator (CPG) model and taking quadruped as an example, the dynamics of CPG model was investigated through the single-parameter-analysis method and the numerical simulation tec... Based on Matsuoka's central pattern generator (CPG) model and taking quadruped as an example, the dynamics of CPG model was investigated through the single-parameter-analysis method and the numerical simulation technique. Simulation results indicate that the CPG model exhibits complex dynamics, while each parameter has specifically definitive influence trends on the CPG output. These conclusions were applied to control a quadrupedal robot to walk in different gaits, clear obstacle, and walk up- and down-slope successfully. 展开更多
关键词 quadrupedal robot rhythmic motion central pattern generator (CPG) parameter dynamics
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Preliminary Group Classification for One Class of Nonlinear Wave Equations 被引量:1
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作者 李吉娜 张颖 张顺利 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第8期229-235,共7页
The group classification is carried out on the nonlinear wave equation utt = f(x,u, ux)uzz + g(x,u,uz) by using the preliminary group classification approach. The generators of equivalence group are determined an... The group classification is carried out on the nonlinear wave equation utt = f(x,u, ux)uzz + g(x,u,uz) by using the preliminary group classification approach. The generators of equivalence group are determined and the corresponding reduced forms are obtained. The result of the work is shown in table form. 展开更多
关键词 preliminary group classification optimal system nonlinear wave equation
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Effects of Uncertainties in the Position and Orientation of Both the Transmitter and Receivers on Marine Controlled-Source Electromagnetic Data 被引量:3
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作者 XU Zhenhuan LIU Ying LI Yuguo 《Journal of Ocean University of China》 SCIE CAS 2016年第1期83-92,共10页
Simulation and interpretation of marine controlled-source electromagnetic(CSEM) data often approximate the transmitter source as an ideal horizontal electric dipole(HED) and assume that the receivers are located on a ... Simulation and interpretation of marine controlled-source electromagnetic(CSEM) data often approximate the transmitter source as an ideal horizontal electric dipole(HED) and assume that the receivers are located on a flat seabed.Actually,however,the transmitter dipole source will be rotated,tilted and deviated from the survey profile due to ocean currents.And free-fall receivers may be also rotated to some arbitrary horizontal orientation and located on sloping seafloor.In this paper,we investigate the effects of uncertainties in the transmitter tilt,transmitter rotation and transmitter deviation from the survey profile as well as in the receiver's location and orientation on marine CSEM data.The model study shows that the uncertainties of all position and orientation parameters of both the transmitter and receivers can propagate into observed data uncertainties,but to a different extent.In interpreting marine data,field data uncertainties caused by the position and orientation uncertainties of both the transmitter and receivers need to be taken into account. 展开更多
关键词 electromagnetic uncertainty in position and orientations data certainty marine CSEM
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One Step on the Smart Grid Path: Load and Generation Coordination in a Virtual Power System 被引量:2
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作者 E. Cagno F. Castelli Dezza +2 位作者 M. Delfanti M. Merlo A. Trianni 《Journal of Energy and Power Engineering》 2011年第3期275-282,共8页
Worldwide the introduction of dispersed generators (DG) in the distribution network is assuming a significant importance. There is an increasing relevance of the energy process efficiency improvement; as for electri... Worldwide the introduction of dispersed generators (DG) in the distribution network is assuming a significant importance. There is an increasing relevance of the energy process efficiency improvement; as for electric power systems, the most interesting perspective concerns the capability of the system to increase the exploitation of the renewable resources. The integration of DGs in the electric distribution network requires a revision of this infrastructure, so far designed and developed assuming that power flows in one direction: from the high voltage transmission network to the medium voltage distribution, to reach final customers on the low voltage network. The attention to an efficient operation of distribution networks is increasing all over the world; this interest is becoming higher and higher also in Italy, where the high energy prices push in the direction of fostering efficiency as much as possible. This work describes a study developed in the AlpEnergy project framework: an International Cooperation Program aimed at introducing an efficient operational model for the distributed production and consumption. In particular it is proposed a new model for the integration and the management of the DG in the distribution network. The new model (defined VPS: Virtual Power System) is based on a communication channel between the active users (generators), the loads and, eventually, the Distribution System Operators (DSOs). 展开更多
关键词 Renewable energy sources distributed generation distributed consumption virtual power plant.
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Wind Energy Potential Assessment in Republic of Macedonia 被引量:1
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作者 V. Dimcev K. Najdenkoski V. Stoilkov Z. Kokolanski 《Journal of Energy and Power Engineering》 2011年第4期324-330,共7页
The paper presents the measurement campaign of wind energy potential undertaken in Republic of Macedonia on four sites from the middle of 2006. The wind data analysis has been performed for one site, following with th... The paper presents the measurement campaign of wind energy potential undertaken in Republic of Macedonia on four sites from the middle of 2006. The wind data analysis has been performed for one site, following with the assessment of energy production of simulated wind park with six wind turbine generators. 展开更多
关键词 Wind energy wind monitoring wind data analysis.
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Sensitivity and effect of key operational parameters on performance of a dual-cylinder free-piston engine generator 被引量:1
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作者 ZHANG Zhi-yuan FENG Hui-hua +1 位作者 JIA Bo-ru ZUO Zheng-xing 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第7期2101-2111,共11页
The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio o... The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated,and their sensitivity was analyzed in this paper.The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position.At the same time,it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15,but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm.The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position.But it is the opposite for the indicated thermal efficiency and friction loss.Excess air ratio and ignition position have a quite similar influence on heat transfer.Therefore,from the perspective of system operation and performance,it is preferable to keep excess air coefficient slightly below 1.0.In contrast,when selecting ignition position,it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure. 展开更多
关键词 free piston engine generator excess air ratio ignition position operation characteristics sensitivity analysis thermal efficiency
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Experimental Investigation of Reynolds Number Effect on Wind Turbine Profiles in the Cryogenic Wind Tunnel Cologne DNW-KKK 被引量:1
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作者 RUdiger Rebstock Junnai Zhai Alois P. Schaffarczy 《Journal of Energy and Power Engineering》 2013年第10期1957-1965,共9页
Wind turbine size has increased continuously and correspondingly also its Reynolds numbers. The Reynolds number effect can therefore no longer be ignored in design and optimization of wind turbines. Reliable profile t... Wind turbine size has increased continuously and correspondingly also its Reynolds numbers. The Reynolds number effect can therefore no longer be ignored in design and optimization of wind turbines. Reliable profile test data should be available. A suitable facility for testing wind turbine profiles at high Reynolds numbers is the Cryogenic Wind Tunnel Cologne DNW-KKK. By means of injecting liquid nitrogen the tunnel can be cooled down to 100 K and the Reynolds number therefore can be raised accordingly. The maximum Reynolds number for 2D profile tests can reach 27x10^6. In this paper the test uncertainty and the flow quality of DNW-KKK were analyzed. Then some test results on the Reynolds number effect of the wind turbine profiles will be presented. The Reynolds number effect is different from model to model. Especially for thick profiles and flow control devices the Reynolds number effect is not always like the description in literature. 展开更多
关键词 Aerodynamics of wind turbine profiles Reynolds number effect cryogenic wind tunnel test.
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Numerical Study on Heat Transfer and Flow Characteristics for Laminar Flow in a Circular Tube with Swirl Generators 被引量:2
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作者 Yongli Sun Guobin Wen +3 位作者 Xiaoming Xiao Bohua Ren Na Yang Luhong Zhang 《Transactions of Tianjin University》 EI CAS 2018年第3期244-255,共12页
This study investigated the heat transfer and flow characteristics of one kind of swirlgenerator in a circular heat exchanger tube through a numericalsimulation. The swirlflow induced by this type of swirlgenerator ca... This study investigated the heat transfer and flow characteristics of one kind of swirlgenerator in a circular heat exchanger tube through a numericalsimulation. The swirlflow induced by this type of swirlgenerator can obtain a high heat transfer rate with minimalpressure drop penalty. The simulations were carried out to understand the physicalbehavior of this kind of mesoscale heat enhancement component. By visualizing the heat transfer and flow characteristics, it is found that the swirlflow is induced by swirlgenerator in the circular tube couples with the impinging jet effect. After passing through the swirlgenerator, the localfriction factor of liquid can quickly return to lower levelmore quickly, while the localNusselt number maintains higher values for a distance; thus, the evaluation criterion of localperformance is improved. Single-factor optimization is used for three geometric parameters, i.e., the angle of swirlgenerator(25o, 45o, and 60o), the length of swirlgenerator(0.005, 0.01, and 0.02 m), and the center rod radius(1, 2, and 3 mm). The optimum parameters of the swirlgenerator for laminar flow of air in a circular tube are obtained, which should be 60o, 0.005 m, and 3 mm, respectively. 展开更多
关键词 Swirl generator Local spatial-temporal characteristic Swirling flow Impinging jet effect
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Numerical Investigations on the Aerodynamic Performance of Wind Turbine: Downwind Versus Upwind Configuration 被引量:7
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作者 Hu Zhou 《Journal of Marine Science and Application》 CSCD 2015年第1期61-68,共8页
Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different a... Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory (NREL) phase V1 wind turbine in downwind and upwind configurations is presented. The open source toolbox OpenFOAM coupled with arbitrary mesh interface (AMI) method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine. 展开更多
关键词 offshore wind energy wind turbine downwind andupwind configuration wake flows arbitrary mesh interface (AMI) OPENFOAM aerodynamic performance
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Passive Matrix Organic Electroluminescent Display for 3G Cellular Phone 被引量:1
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作者 LI Xiang dong, YANG Jia de (Chongqing Optoelectronics Research Institute, Chongqing 400060, CHN) 《Semiconductor Photonics and Technology》 CAS 2001年第4期247-252,共6页
The major features of the display technologies for 3G cellular phone are reviewed. The comparison between their potential candidates for 3G cellular phone is given, and a detailed discussion is made on passive matrix ... The major features of the display technologies for 3G cellular phone are reviewed. The comparison between their potential candidates for 3G cellular phone is given, and a detailed discussion is made on passive matrix organic electroluminescent display technology. A novel method to improve display contrast ratio is presented. Finally several 3G phone set prototypes with OLED display panels are given as well as the market forecast. 展开更多
关键词 3G cellular phone Organic electroluminescent display Passive matrix drive Active matrix drive Duty ratio
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A New Approach to Calculate Parameters of Induction Generator with Double Windings
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作者 刘长红 姚若萍 《Journal of Shanghai Jiaotong university(Science)》 EI 2005年第2期186-189,共4页
The accuracy prediction for the performance of an induction generator depends much on the parameters of the equivalent circuit. This paper presented a new way for calculating these parameters of induction generator wi... The accuracy prediction for the performance of an induction generator depends much on the parameters of the equivalent circuit. This paper presented a new way for calculating these parameters of induction generator with double windings. The method is based on 2D time-dependent magnetic field coupled with electric circuit. An application example of a 12-phase self-excited induction generator (SEIG) was provided to demonstrate the effectiveness of the presented approach. Some of the calculated results show good coincidence with the experiment values. 展开更多
关键词 equivalent parameters self-excited induction generators double windings FEM
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A Short Note on the Conjugation in the Leibniz-Hopf Algebra
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作者 Neset Deniz Turgay 《Journal of Mathematics and System Science》 2014年第1期34-36,共3页
The Leibniz-Hopf algebra is the free associative Z - algebra with one generator in each positive degree and coproduct is given by the Cartan formula. It has been also known as the 'ring ofnoncommutative symmetric fun... The Leibniz-Hopf algebra is the free associative Z - algebra with one generator in each positive degree and coproduct is given by the Cartan formula. It has been also known as the 'ring ofnoncommutative symmetric functions' [1], and to be isomorphic to the Solomon Descent algebra [ 12]. This Hopf algebra has links with algebra,topology and combinatorics. In this article we consider another approach of proof for the antipode formula in the Leibniz-Hopf algebra by using some properties of words in [2]. 展开更多
关键词 Hopfalgebra Leibniz-Hopf algebra ANTIPODE Steenrod algebra.
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Design and Guideline Rules for the Performance Improvement of Vertically Integrated Nanogenerator
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作者 Ronan Hinchet Sangmin Lee +3 位作者 Gustavo Ardila Laurent Montes Mireille Mouis Zhong Lin Wang 《Journal of Energy and Power Engineering》 2013年第9期1816-1820,共5页
Piezoelectric nanowires have attracted much scientific interest in the last few years because of their enhanced piezoelectric coefficients at nanometer scale, with promises of efficient mechanical energy harvesters fo... Piezoelectric nanowires have attracted much scientific interest in the last few years because of their enhanced piezoelectric coefficients at nanometer scale, with promises of efficient mechanical energy harvesters for autonomous integrated systems. This paper presents the design and, for the first time, guideline rules, based on simple analytical expressions, to improve the performance of a mechanical energy harvester integrating vertical ZnO piezoelectric nanowires. Additional simulations were carried out to account more realistically for device geometry. The authors discuss the prospects of such an approach, based on design and material improvement. 展开更多
关键词 NANOGENERATOR ZINC-OXIDE PIEZOELECTRIC NANOWIRE mechanical energy harvesting.
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Development of a Full Parameterized FE-modeling Tool for Efficient Vibration Investigations on End Windings of Turbo- and Hydro-Generators
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作者 Bemd Schlegl Christian Scheinecker +3 位作者 Andreas Marn Fritz Neumayer Mario Himmelreich Franz Heitmeir 《Journal of Energy and Power Engineering》 2013年第8期1496-1504,共9页
End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windin... End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements. Due to the complex structure and unknown boundary conditions, the conventionally calculation of stator end windings has been very difficult and time consuming up to now. This paper describes the development of a full parameterized modeling tool, which allows a quick calculation of natural frequencies during the design phase of the generator. To keep the computing time low, it is important to find a way to get exact calculation results without detailed modeling of all pans. Additionally, special attention was paid to the active part, which has been replaced by spring-damper elements, and the determination of their stiffness via experimental modal analysis combined with finite element calculations. 展开更多
关键词 Electrical machines end windings finite element method generators hydro generator power generation vibrationproblems.
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The Double Excitation: A Solution to Improve Energetic Performances of High Power Synchronous Machines
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作者 Aymen Ammar Frederic Gillon Pascal Brochet 《Journal of Energy and Power Engineering》 2012年第5期719-724,共6页
DFSM (doubly fed synchronous machine) presents several advantages such as efficiency improvement, weight reduction and increase of the utilization factor (kW/kg). In this paper the authors focus on impact of the D... DFSM (doubly fed synchronous machine) presents several advantages such as efficiency improvement, weight reduction and increase of the utilization factor (kW/kg). In this paper the authors focus on impact of the DFSM on the efficiency and machine weight in comparison to conventional synchronous generator with wound rotor. Different topologies of DFSM are briefly described and the different methods and models for performances prediction are presented. 展开更多
关键词 Double excitation LOSSES no load characteristic permanent magnet reluctances network vector diagram.
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