Energy Technology Data Exchange (ETDEWEB)
Chakraborty, S.; Kroposki, B.; Kramer, W.
2008-11-01
Integrating renewable energy and distributed generations into the Smart Grid architecture requires power electronic (PE) for energy conversion. The key to reaching successful Smart Grid implementation is to develop interoperable, intelligent, and advanced PE technology that improves and accelerates the use of distributed energy resource systems. This report describes the simulation, design, and testing of a single-phase DC-to-AC inverter developed to operate in both islanded and utility-connected mode. It provides results on both the simulations and the experiments conducted, demonstrating the ability of the inverter to provide advanced control functions such as power flow and VAR/voltage regulation. This report also analyzes two different techniques used for digital signal processor (DSP) code generation. Initially, the DSP code was written in C programming language using Texas Instrument's Code Composer Studio. In a later stage of the research, the Simulink DSP toolbox was used to self-generate code for the DSP. The successful tests using Simulink self-generated DSP codes show promise for fast prototyping of PE controls.
MPC of Single Phase Inverter for PV System
Irtaza M. Syed; Kaamran Raahemifar
2014-01-01
This paper presents a model predictive control (MPC) of a utility interactive (UI) single phase inverter (SPI) for a photovoltaic (PV) system at residential/distribution level. The proposed model uses single-phase phase locked loop (PLL) to synchronize SPI with the grid and performs MPC control in a dq reference frame. SPI model consists of boost converter (BC), maximum power point tracking (MPPT) control, and a full bridge (FB) voltage source inverter (VSI). No PI regula...
A Transformer-less Single Phase Inverter For photovoltaic Systems
DEFF Research Database (Denmark)
Mostaan, Ali; Alizadeh, Ebrahim; Qu, Ying
2017-01-01
A single phase transformer-less inverter is introduced in this paper. The negative polarities of the input voltage and output terminal have common ground. Therefore, the leakage current problem that is common in PV systems is eliminated naturally. In addition, the proposed inverter has fewer...... components compared with its counterparts and only one switch conducts during the active states which enhance the inverter efficiency. The proposed inverter is analyzed in details and compared with some existing topologies. The performance of the proposed inverter is validated using the simulation results....
Current Harmonics from Single-Phase Grid-Connected Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede
2016-01-01
factor, or in the low voltage ride through mode with reactive current injection. In this paper, the mechanism of the harmonic current injection from grid-connected single-phase inverter systems is thus explored, and the analysis is conducted on single-phase PV systems. In particular, the analysis......-phase applications as a promising harmonic mitigation solution. Experiments on single-phase grid-connected systems have verified the correctness of the relevant analysis and also the effectiveness of the tailor-made control solution in terms of good harmonic mitigation....
A single phase photovoltaic inverter control for grid connected system
Indian Academy of Sciences (India)
This paper presents a control scheme for single phase grid connected photovoltaic (PV) system operating under both grid connected and isolated grid mode. The control techniques include voltage and current control of grid-tie PV inverter. During grid connected mode, grid controls the amplitude and frequency of the PV ...
Control of Single-Stage Single-Phase PV inverter
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented...
Modeling of a single-phase photovoltaic inverter
Energy Technology Data Exchange (ETDEWEB)
Maris, T.I. [Department of Electrical Engineering, Technological Educational Institute of Chalkida, 334 40 Psachna Evias (Greece); Kourtesi, St. [Hellenic Public Power Corporation S.A., 22 Chalcocondyli Str., 104 32 Athens (Greece); Ekonomou, L. [Hellenic American University, 12 Kaplanon Str., 106 80 Athens (Greece); Fotis, G.P. [National Technical University of Athens, School of Electrical and Computer Engineering, High Voltage Laboratory, 9 Iroon Politechniou St., Zografou, 157 80 Athens (Greece)
2007-11-06
The paper presents the design of a single-phase photovoltaic inverter model and the simulation of its performance. Furthermore, the concept of moving real and reactive power after coupling this inverter model with an a.c. source representing the main power distribution grid was studied. Brief technical information is given on the inverter design, with emphasis on the operation of the circuit used. In the technical information section, a description of real and reactive power components is given with special reference to the control of these power components by controlling the power angle or the difference in voltage magnitudes between two voltage sources. This a.c. converted voltage has practical interest, since it is useful for feeding small house appliances. (author)
Control of Single-Stage Single-Phase PV inverter
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented......-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter........ The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; - the input power control using the dc voltage controller and power feed...
Performance Improvement of Single Phase Inverter using SPWM
Gavaskar Reddy, B., Dr; Maheswari, L., Dr; Ganeswari Kale, Adi
2017-08-01
This paper concentrates on modelling and simulation of single phase inverter as a frequency changer modulated by Pulse Width Modulation (PWM). An inverter is a circuit that converts DC sources to AC sources. Pulse Width Modulation is a method that utilization as an approach to abatement add up to harmonic distortion in inverter circuit. The model is executed utilizing MATLAB/Simulink software with the SimPower System Block Set in light of PC simulation. PC simulation assumes an imperative part in the plan, investigation, and assessment of force electronic converter and their controller. MATLAB is a successful instrument to examine a PWM inverter. Preferences of utilizing MATLAB are the accompanying: Faster reaction, accessibility of different simulation devices and utilitarian squares and the nonappearance of joining issues. Safe-replacement methodology need be actualized is to explain exchanging Transients. In this way, Insulated Gate Bipolar Transistor (IGBT) is use as exchanging gadgets. IGBT is ideal since it is anything but difficult to control and low misfortunes. The outcome from Simulink was checked utilizing MATLAB simulation.
A grid-connected single-phase photovoltaic micro inverter
Wen, X. Y.; Lin, P. J.; Chen, Z. C.; Wu, L. J.; Cheng, S. Y.
2017-11-01
In this paper, the topology of a single-phase grid-connected photovoltaic (PV) micro-inverter is proposed. The PV micro-inverter consists of DC-DC stage with high voltage gain boost and DC-AC conversion stage. In the first stage, we apply the active clamp circuit and two voltage multipliers to achieve soft switching technology and high voltage gain. In addition, the flower pollination algorithm (FPA) is employed for the maximum power point tracking (MPPT) in the PV module in this stage. The second stage cascades a H-bridge inverter and LCL filter. To feed high quality sinusoidal power into the grid, the software phase lock, outer voltage loop and inner current loop control method are adopted as the control strategy. The performance of the proposed topology is tested by Matlab/Simulink. A PV module with maximum power 300W and maximum power point voltage 40V is applied as the input source. The simulation results indicate that the proposed topology and the control strategy are feasible.
Reducing Electromagnetic Interference in a Grid Tied Single Phase Power Inverter
2016-09-01
ELECTROMAGNETIC INTERFERENCE IN A GRID TIED SINGLE PHASE POWER INVERTER by Jason Hassan Valiani September 2016 Thesis Advisor: Giovanna Oriti...3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE REDUCING ELECTROMAGNETIC INTERFERENCE IN A GRID TIED SINGLE PHASE POWER...The addition of a passive filter proved to minimize the conducted EMI for a single -phase grid-tied inverter. 14. SUBJECT TERMS single -phase
A single phase photovoltaic inverter control for grid connected system
Indian Academy of Sciences (India)
during light load condition the excess energy generated from the PV inverter is fed to the grid and; during an overload condition or in case of unfavorable atmospheric conditions the load demand is met by both PV inverter and the grid. In order to synchronize the PV inverter with the grid a dual transport delay based phase ...
A Novel Model Predictive Control for Single-Phase Grid-Connected Photovoltaic Inverters
DEFF Research Database (Denmark)
Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil
2017-01-01
Single-phase grid-connected inverters with LCL filter are widely used to connect photovoltaic systems to the utility grid. Among the existing control schemes, predictive control methods are faster and more accurate but also more complicated to implement. Recently, the Model Predictive Control (MPC......) algorithm for single-phase inverter has been presented, where the algorithm implementation is straightforward. In the MPC approach, all switching states are considered in each switching period to achieve the control objectives. However, since the number of switching states in single-phase inverters is small...... vectors. Simulation results show that the proposed approach lead to a lower THD in the injected current combined with fast dynamics. The proposed predictive control has been simulated and implemented on a 1 kW single-phase HERIC (highly efficient and reliable inverter concept) inverter with an LCL filter...
Single phase inverter for a three phase power generation and distribution system
Lindena, S. J.
1976-01-01
A breadboard design of a single-phase inverter with sinusoidal output voltage for a three-phase power generation and distribution system was developed. The three-phase system consists of three single-phase inverters, whose output voltages are connected in a delta configuration. Upon failure of one inverter the two remaining inverters will continue to deliver three-phase power. Parallel redundancy as offered by two three-phase inverters is substituted by one three-phase inverter assembly with high savings in volume, weight, components count and complexity, and a considerable increase in reliability. The following requirements must be met: (1) Each single-phase, current-fed inverter must be capable of being synchronized to a three-phase reference system such that its output voltage remains phaselocked to its respective reference voltage. (2) Each single-phase, current-fed inverter must be capable of accepting leading and lagging power factors over a range from -0.7 through 1 to +0.7.
DEFF Research Database (Denmark)
Guo, Xiaoqiang; Jia, X.; Lu, Z.
2016-01-01
Leakage current reduction is one of the important issues for the transformelress PV systems. In this paper, the transformerless single-phase cascaded H-bridge PV inverter is investigated. The common mode model for the cascaded H4 inverter is analyzed. And the reason why the conventional cascade H...
A review of single-phase grid-connected inverters for photovoltaic modules
DEFF Research Database (Denmark)
Kjaer, Soren Baekhoej; Pedersen, John Kim; Blaabjerg, Frede
2005-01-01
This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single...
Solar-Based Boost Differential Single Phase Inverter | Eya | Nigerian ...
African Journals Online (AJOL)
... current concurrently and finally, it is portable. This research also shows the disparity between the simulated results of open loop and closed loop of boost differential inverter systems. The dc power source is photovoltaic cell. The maximum power point tracker is in-cooperated in capturing the maximum power from the sun.
A single phase photovoltaic inverter control for grid connected system
Indian Academy of Sciences (India)
tracking (MPPT) controller is used which enables the maximum power extraction under varying irradiation and temperature conditions. The validity of the proposed system is verified through simulation as well as hardware implementation. Keywords. Current controller; MPPT; photovoltaic; PLL; PV inverter; voltage controller.
A new type of single-phase five-level inverter
Xu, Zhi; Li, Shengnan; Qin, Risheng; Zhao, Yanhang
2017-11-01
At present, Neutral Point Clamped (NPC) multilevel inverter is widely applied in new energy field. However, it has some disadvantages including low utilization rate of direct current (DC) voltage source and the unbalance of neutral potential. Therefore, a new single-phase five level inverter is proposed in this paper. It has two stage structure, the former stage is equivalent to three level DC/DC converter, and the back stage uses H bridge to realize inverter. Compared with the original central clamp type inverter, the new five level inverter can improve the utilization of DC voltage, and realize the neutral point potential balance with hysteresis comparator.
Improved PLL structures for single-phase grid inverters
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
of the reference signals. This paper presents two improved phase-locked-loop (PLL) methods for single-phase grid connected systems. The investigated PLL methods are based on a transport delay method and an inverse Park transformation method. The improvements in the case of using the delay-based PLL are: non......-frequency dependent and better filtering of the harmonics. For the other investigated PLL method based on inverse Park transformation the improvement consists of better filtering of the harmonics. Experimental results validate the effectiveness of the two proposed methods....
Microcontroller Based SPWM Single-Phase Inverter For Wind Power Application
Directory of Open Access Journals (Sweden)
Khin Ohmar Lin
2017-04-01
Full Text Available In this paper microcontroller based sinusoidal pulse width modulation SPWM single-phase inverter is emphasized to constant frequency conversion scheme for wind power application. The wind-power generator output voltage and frequency are fluctuated due to the variation of wind velocity. Therefore the AC output voltage of wind-generator is converted into DC voltage by using rectifier circuit and this DC voltage is converted back to AC voltage by using inverter circuit. SPWM technique is used in inverter to get nearly sine wave and reduce harmonic content. The rating of inverter is 500W single-phase 220V 50 Hz. The required SPWM timing pulses for the inverter are generated from the PIC16F877A microcontroller. Circuit simulation was done by using Proteus 7 Professional and MATLABR 2008 software. The software for microcontroller is implemented by using MPASM assembler.
Single Phase Transformer-less Buck-Boost Inverter with Zero Leakage Current for PV Systems
DEFF Research Database (Denmark)
Mostaan, Ali; Abdelhakim, Ahmed; N. Soltani, Mohsen
2017-01-01
In this paper, a novel single-stage single-phase transformer-less buck-boost inverter is proposed, in which a reduced number of passive components is used. The proposed inverter combines the conventional buck, boost, and buck-boost converters in one converter in order to obtain a sinusoidal output...... voltage. In the proposed inverter, the input DC source and the load or grid have the same ground. Therefore, the leakage current problem in photovoltaic (PV) systems is eliminated. Furthermore, the proposed inverter supports the bi-directional power flow capability and it can inject reactive power...
Modelling of the modified-LLCL-filter-based single-phase grid-tied Aalborg inverter
DEFF Research Database (Denmark)
Liu, Zifa; Wu, Huiyun; Liu, Yuan
2017-01-01
Owing to less conduction and switching power losses, the recently proposed Aalborg inverter has high efficiency within a wide range of input DC voltage for single-phase DC/AC power conversion. In theory, the conduction power losses can be further decreased, if an LLCL-filter is adopted instead....... In this study, the small signal analysis for the modified-LLCL-filter-based Aalborg inverter is addressed. Through the modelling, it can be proven that compared with the LCL-filter, the modified-LLCL-filter causes no extra control challenge for the Aalborg inverter, and therefore more inductance in the power...... of an LCL-filter for a voltage source inverter, mainly due to the reduced inductance. The Aalborg inverter shows the characteristic of a current source inverter, when working in the `boost' state. Whether the LLCL-filter can meet the control requirement of this type inverter needs to be further explored...
Common-Ground-Type Tansformerless Inverters for Single-Phase Solar Photovoltaic Systems
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede
2018-01-01
This paper proposes a family of novel flying capacitor transformerless inverters for single-phase photovoltaic (PV) systems. Each of the new topologies proposed is based on a flying capacitor principle and requires only four power switches and/or diodes, one capacitor, and a small filter at the o......This paper proposes a family of novel flying capacitor transformerless inverters for single-phase photovoltaic (PV) systems. Each of the new topologies proposed is based on a flying capacitor principle and requires only four power switches and/or diodes, one capacitor, and a small filter...
Challenges in thermal design of industrial single-phase power inverter
Directory of Open Access Journals (Sweden)
Ninković Predrag
2016-01-01
Full Text Available This paper presents the influence of thermal aspects in design process of an industrial single-phase inverter, choice of its topology and components. Stringent design inputs like very high overload level, demand for natural cooling and very wide input voltage range have made conventional circuit topology inappropriate therefore asking for alternative solution. Different power losses calculations in semiconductors are performed and compared, outlining the guidelines how to choose the final topology. Some recommendations in power magnetic components design are given. Based on the final project, a 20kVA single-phase inverter for thermal power plant supervisory and control system is designed and commissioned.
DEFF Research Database (Denmark)
Husev, Oleksandr; Strzelecki, Ryszard; Blaabjerg, Frede
2016-01-01
This paper describes novel single-phase solutions with increased inverter voltage levels derived by means of a nonstandard inverter configuration and impedance source networks. Operation principles based on special modulation techniques are presented. Detailed component design guidelines along wi...
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede
2016-01-01
This paper proposes a new single-phase flying capacitor transformerless PV inverter for grid-connected photovoltaic (PV) systems. The neutral of the grid can be directly connected to the negative terminal of the source (PV). It consists of four power switches, one diode, one capacitor and a small...
A single phase multilevel inverter as power converter for 3-phase ...
African Journals Online (AJOL)
A single phase multilevel inverter as power converter for 3-phase electric loads. ... m-phase maker was simulated using MATLAB and the results confirmed the excellent perfor-mance of the RBNPS. The listed advantages attained could be incorporated in the design and operation of a converter for an electric drive of a car.
Low Voltage Ride-Through of Single-Phase Transformerless Photovoltaic Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Wang, Huai
2014-01-01
, e.g. Low Voltage Ride-Through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults are explored in this paper. Control strategies with reactive power injections...
PI and repetitive control for single phase inverter based on virtual rotating coordinate system
Li, Mengqi; Tong, Yibin; Jiang, Jiuchun; Liang, Jiangang
2018-03-01
Microgrid technology developed rapidly and nonlinear loads were connected increasingly. A new control strategy was proposed for single phase inverter when connected nonlinear loads under island condition. PI and repetitive compound controller was realized under synchronous rotating coordinate system and acquired high quality sinusoidal voltage output without voltage spike when loads step changed. Validity and correctness were verified by simulation using MATLAB/Simulink.
Single-Phase 3L PR Controlled qZS Inverter Connected to the Distorted Grid
DEFF Research Database (Denmark)
Makovenko, Elena; Husev, Oleksandr; Roncero-Clemente, Carlos
2016-01-01
This paper presents a single-phase three-level NPC qZS inverter connected to a distorted grid using PID and PR regulators. A case study system along with the control strategy are described. Tuning approaches for PID and PR regulators are addressed and validated by means of simulation results...
Control Method of Single-phase Inverter Based Grounding System in Distribution Networks
DEFF Research Database (Denmark)
Wang, Wen; Yan, L.; Zeng, X.
2016-01-01
of neutral-to-ground voltage is critical for the safety of distribution networks. An active grounding system based on single-phase inverter is proposed to achieve this objective. Relationship between output current of the system and neutral-to-ground voltage is derived to explain the principle of neutral...
A Direct Maximum Power Point Tracking Method for Single-Phase Grid Connected PV Inverters
DEFF Research Database (Denmark)
EL Aamri, Faicel; Maker, Hattab; Sera, Dezso
2018-01-01
in dynamic conditions, especially in low irradiance when the measurement of signals becomes more sensitive to noise. The proposed MPPT is designed for single-phase single-stage grid-connected PV inverters, and is based on estimating the instantaneous PV power and voltage ripples, using second...
Reliability Evaluation of a Single-phase H-bridge Inverter with Integrated Active Power Decoupling
DEFF Research Database (Denmark)
Tang, Junchaojie; Wang, Haoran; Ma, Siyuan
2016-01-01
Various power decoupling methods have been proposed recently to replace the DC-link Electrolytic Capacitors (E-caps) in single-phase conversion system, in order to extend the lifetime and improve the reliability of the DC-link. However, it is still an open question whether the converter level...... reliability becomes better or not, since additional components are introduced and the loading of the existing components may be changed. This paper aims to study the converter level reliability of a single-phase full-bridge inverter with two kinds of active power decoupling module and to compare...... it with the traditional passive DC-link solution. The converter level reliability is obtained by component level electro-thermal stress modeling, lifetime model, Weibull distribution, and Reliability Block Diagram (RBD) method. The results are demonstrated by a 2 kW single-phase inverter application....
An LLCL Power Filter for Single-Phase Grid-Tied Inverter
DEFF Research Database (Denmark)
Wu, Weimin; He, Yuanbin; Blaabjerg, Frede
2012-01-01
This paper presents a new topology of higher order power filter for grid-tied voltage-source inverters, named the LLCL filter, which inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency...... to the inverter system control. The parameter design criteria of the proposed LLCL filter is also introduced. The comparative analysis and discussions regarding the traditional LCL filter and the proposed LLCL filter have been presented and evaluated through experiment on a 1.8-kW-single-phase grid-tied inverter...
High Quality Model Predictive Control for Single Phase Grid Connected Photovoltaic Inverters
DEFF Research Database (Denmark)
Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil
2018-01-01
Single phase grid-connected inverters with LCL filter are widely used to connect the photovoltaic systems to the utility grid. Among the presented control schemes, predictive control methods are faster and more accurate but are more complex to implement. Recently, the model-predictive control...... is low, the inverter output current has a high total harmonic distortions. In order to reduce the total harmonic distortions of the injected current, this paper presents a high-quality model-predictive control for one of the newest structure of the grid connected photovoltaic inverter, i.e., HERIC...
Power decoupling with autonomous reference generation for single-phase differential inverters
DEFF Research Database (Denmark)
Yao, Wenli; Zhang, Xiaobin; Wang, Xiongfei
2015-01-01
The second-harmonic power ripple in single-phase inverter may introduce the issue of low reliability and low power density. In order to replace the bulky dc-link capacitor, an alternative approach is to use active power decoupling so that the ripple power can be diverted into other energy storages...... are used for realizing an improved power decoupling control, capacitor voltage and inductor current regulation. By substituting the corresponding parameter into unified model, the proposed control loop can be applied to different inverter types (Buck, Buck-Boost and Boost). Finally, detailed laboratory....... However, the performance of existing active power decoupling methods depends heavily on certain control references, which unfortunately are parameter dependent. In this paper an autonomous reference generation technique is proposed for single phase differential inverter without relying on the system...
Low voltage ride-through of single-phase transformerless photovoltaic inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Wang, Huai
2013-01-01
Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV...... systems due to anti-islanding protection may trigger grid disturbances. Thus, standards featuring with ancillary services for the next generation PV systems are under a revision in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e...... discussed. The selected inverters are the full-bridge inverter with bipolar modulation, full-bridge inverter with DC bypass and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1 kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although...
A single-phase embedded Z-source DC-AC inverter.
Kim, Se-Jin; Lim, Young-Cheol
2014-01-01
In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.
S4 Grid-Connected Single-Phase Transformerless Inverter for PV Application
DEFF Research Database (Denmark)
Ardashir, Jaber Fallah; Siwakoti, Yam Prasad; Sabahi, Mehran
2016-01-01
This paper introduces a new single-phase transformerless inverter for grid-connected photovoltaic systems with low leakage current. It consists of four power switches, two diodes, two capacitors and a filter at the output stage. The neutral of the grid is directly connected to the negative terminal...... of the PV source. This results in a constant common-mode voltage and almost zero leakage current. A unipolar Sinusoidal Pulse-Width Modulation (SPWM) technique is used to modulate the inverter to reduce the output current ripple and the filter requirements. The main advantages of this inverter are compact...... clearly verify the performance of the proposed inverter and its practical application for grid-connected PV systems....
A unified active damping control for single-phase differential buck inverter with LCL-filter
DEFF Research Database (Denmark)
Yao, Wenli; Wang, Xiongfei; Zhang, Xiaobin
2015-01-01
and control of a grid-connected differential mode buck inverter with an LCL filter. A generalized small-signal model of the inverter is built first with the averaged switching model. It is shown that the LCL filter resonance merely occurs in the differential mode, while an LC filter resonance exists......The single-phase differential mode buck inverter is recently introduced with a differential mode for power transfer and a common mode for actively decoupling the second-order power oscillation. However, it is limited to islanded applications with an LC filter. This paper addresses the stability...... in the common mode, provided that the filter parameters of the two bridges are kept the same. A unified active damping control approach is then proposed for stabilizing the inverter and improving the transient performance under a wide range of grid impedance. Lastly, experimental tests are carried out...
Ismail, K.; Muharam, A.; Amin; Widodo Budi, S.
2015-12-01
Inverter is widely used for industrial, office, and residential purposes. Inverter supports the development of alternative energy such as solar cells, wind turbines and fuel cells by converting dc voltage to ac voltage. Inverter has been made with a variety of hardware and software combinations, such as the use of pure analog circuit and various types of microcontroller as controller. When using pure analog circuit, modification would be difficult because it will change the entire hardware components. In inverter with microcontroller based design (with software), calculations to generate AC modulation is done in the microcontroller. This increases programming complexity and amount of coding downloaded to the microcontroller chip (capacity flash memory in the microcontroller is limited). This paper discusses the design of a single phase inverter using unipolar modulation of sine wave and triangular wave, which is done outside the microcontroller using data processing software application (Microsoft Excel), result shows that complexity programming was reduce and resolution sampling data is very influence to THD. Resolution sampling must taking ½ A degree to get best THD (15.8%).
Frequency Adaptive Repetitive Control of Grid-Tied Single-Phase PV Inverters
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
. This paper thus explores a frequency adaptive repetitive control strategy for grid converters, which employs fractional delay filters in order to adapt to the change of the grid frequency. Case studies with experimental results of a single-phase grid-connected PV inverter system are provided to verify......The internal model principle based Repetitive Control (RC) offers an accurate control strategy for grid-tied power converters to feed sinusoidal current into the grid. However, in the presence of grid frequency variations, the conventional RC fails to produce high quality feeding current...... the proposed controller....
Adaptive fuzzy sliding control of single-phase PV grid-connected inverter.
Directory of Open Access Journals (Sweden)
Juntao Fei
Full Text Available In this paper, an adaptive fuzzy sliding mode controller is proposed to control a two-stage single-phase photovoltaic (PV grid-connected inverter. Two key technologies are discussed in the presented PV system. An incremental conductance method with adaptive step is adopted to track the maximum power point (MPP by controlling the duty cycle of the controllable power switch of the boost DC-DC converter. An adaptive fuzzy sliding mode controller with an integral sliding surface is developed for the grid-connected inverter where a fuzzy system is used to approach the upper bound of the system nonlinearities. The proposed strategy has strong robustness for the sliding mode control can be designed independently and disturbances can be adaptively compensated. Simulation results of a PV grid-connected system verify the effectiveness of the proposed method, demonstrating the satisfactory robustness and performance.
Adaptive fuzzy sliding control of single-phase PV grid-connected inverter.
Fei, Juntao; Zhu, Yunkai
2017-01-01
In this paper, an adaptive fuzzy sliding mode controller is proposed to control a two-stage single-phase photovoltaic (PV) grid-connected inverter. Two key technologies are discussed in the presented PV system. An incremental conductance method with adaptive step is adopted to track the maximum power point (MPP) by controlling the duty cycle of the controllable power switch of the boost DC-DC converter. An adaptive fuzzy sliding mode controller with an integral sliding surface is developed for the grid-connected inverter where a fuzzy system is used to approach the upper bound of the system nonlinearities. The proposed strategy has strong robustness for the sliding mode control can be designed independently and disturbances can be adaptively compensated. Simulation results of a PV grid-connected system verify the effectiveness of the proposed method, demonstrating the satisfactory robustness and performance.
Modified Dual Three-Pulse Modulation technique for single-phase inverter topology
Sree Harsha, N. R.; Anitha, G. S.; Sreedevi, A.
2016-01-01
In a recent paper, a new modulation technique called Dual Three Pulse Modulation (DTPM) was proposed to improve the efficiency of the power converters of the Electric/Hybrid/Fuel-cell vehicles. It was simulated in PSIM 9.0.4 and uses analog multiplexers to generate the modulating signals for the DC/DC converter and inverter. The circuit used is complex and many other simulation softwares do not support the analog multiplexers as well. Also, the DTPM technique produces modulating signals for the converter, which are essentially needed to produce the modulating signals for the inverter. Hence, it cannot be used efficiently to switch the valves of a stand-alone inverter. We propose a new method to generate the modulating signals to switch MOSFETs of a single phase Dual-Three pulse Modulation based stand-alone inverter. The circuits proposed are simulated in Multisim 12.0. We also show an alternate way to switch a DC/DC converter in a way depicted by DTPM technique both in simulation (MATLAB/Simulink) and hardware. The circuitry is relatively simple and can be used for the further investigations of DTPM technique.
Analysis of phase-locked loop influence on the stability of single-phase grid-connected inverter
DEFF Research Database (Denmark)
Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede
2015-01-01
A controlled power inverter can cause instability at the point of common coupling (PCC) with its output filter and the grid. This paper analyzes the influence of the Phase-Locked Loop (PLL) on the output admittance of single-phase current-controlled inverters with different grid stiffness. It shows...
Space Vector Pulse Width Modulation Strategy for Single-Phase Three-Level CIC T-source Inverter
DEFF Research Database (Denmark)
Shults, Tatiana E.; Husev, Oleksandr O.; Blaabjerg, Frede
2016-01-01
This paper presents a novel space vector pulse-width modulation strategy for a single-phase three-level buck-boost inverter based on an impedance-source network. The case study system is based on T-source inverter with continuous input current. To demonstrate the improved performance of the inver...
Directory of Open Access Journals (Sweden)
Jiao Jiao
2016-11-01
Full Text Available Explored in this paper is the grid impedance effect on the stability of a single-phase grid connected inverter with an LC filter based on an analysis of the inverter output impedance. For a single-phase grid connected inverter, a PI controller is often used to regulate the current injected into the grid. However, the control performance can be influenced when the inverter is connected to a weak grid. Also, the utility grid has background harmonic noise, which can make the injected current distorted. Therefore, analysis of the output impedance of a single-phase grid connected inverter is important for the robustness and stability of the system. By modeling the output impedance of inverter, it can be determined that the proportional gain and integral gain of the controller have an effect on the output impedance. Analytical results show that by adjusting the PI controller parameters, the ability for harmonic reduction and stability of the system can be improved. Simulation and experiments using a 1 kW single-phase grid connected inverter verify the effectiveness of the theoretical analysis.
Energy Technology Data Exchange (ETDEWEB)
Nakae, T. [Kanazawa Technical College, Ishikawa (Japan); Kanamaru, Y.; Amemiya, Y. [Kanazawa Institute of Technology, Ishikawa (Japan)
1998-09-01
A method for PWM control of inverter circuits in photovoltaic power generation systems is developed to connect them to utility power supply systems for residences. For controlling sine-wave PWM inverters, it is possible to control a basic wave voltage for inverter output in a range from 0 to 100% by the on-off actions of the switching device, after comparing heights of the carrier wave (triangular wave) and signal wave (sine wave) with each other, to change the signal wave amplitude. The authors has proposed a new method in which the carrier wave is swung over the positive and negative regions corresponding to the positive and negative signal wave, and the on-off phase of the switching device is deviated a little from the phase determined by comparing heights of the carrier and signal waves with each other. Basic wave voltage for inverter output can be increased by about 18%, e.g., at a modulation degree of 80%, from the level obtained by the conventional method. In other words, it is possible to reduce photovoltaic cell array voltage by 15% (i.e., 1/1.18 = 0.85 times) to obtain the same voltage as given by the conventional method. Number of cell modules can be reduced by that, accordingly. The effect of the harmonic component is found to be small. 7 refs., 9 figs., 3 tabs.
DEFF Research Database (Denmark)
Wang, Huai; Yang, Yongheng; Blaabjerg, Frede
2013-01-01
. A reliability-oriented design guideline is proposed in this paper for the input capacitors in single-phase transformer-less PV inverters. The guideline ensures that the service time requirement is to be accomplished under different power levels and ambient temperature profiles. The theoretical analysis has been......While 99% efficiency has been reported, the target of 20 years of service time imposes new challenge to cost-effective solutions for grid-connected photovoltaic (PV) inverters. Aluminum electrolytic capacitors are the weak-link in terms of reliability and lifetime in single-phase PV systems...
DEFF Research Database (Denmark)
Wang, Huai; Yang, Yongheng; Blaabjerg, Frede
2013-01-01
. At the same time, the target of a long service time (25 years or more) imposes new challenges to grid-connected transformer-less PV systems. Achieving more reliable PV inverters is of intense interest in recent research. As one of the most critical stresses that induce failures, the thermal stresses...... on the power devices of a single-phase full-bridge PV inverter are analyzed in different operational modes in this paper. The low voltage grid condition is specially taken into account in this paper. The analysis is demonstrated by a 3 kW single-phase full-bridge grid-connected PV system by simulations...
DEFF Research Database (Denmark)
Ardashir, Jaber Fallah; Sabahi, Mehran; Hosseini, Seyed Hossein
2017-01-01
This paper proposes a new single-phase transformerless photovoltaic (PV) inverter for grid-tied PV systems. The topology is derived from the concept of a charge pump circuit in order to eliminate the leakage current. It is composed of four power switches, two diodes, two capacitors, and an LCL ou...
DEFF Research Database (Denmark)
Abdelhakim, Ahmed; Mattavelli, Paolo; Davari, Pooya
2018-01-01
This paper investigates and evaluates the performance of a single-phase split-source inverter (SSI), where an alternative unidirectional dc-ac configuration is used. Such configuration is utilized in order to use two common-cathode diodes in a single-device instead of using two separate diodes, r...
Adaptive Hysteresis Band Current Control for Transformerless Single-Phase PV Inverters
DEFF Research Database (Denmark)
Vázquez, Gerardo; Rodriguez, Pedro; Ordoñez, Rafael
2009-01-01
Current control based on hysteresis algorithms are widely used in different applications, such as motion control, active filtering or active/reactive power delivery control in distributed generation systems. The hysteresis current control provides to the system a fast and robust dynamic response,...... different single-phase PV inverter topologies, by means of simulations performed with PSIM. In addition, the behavior of the thermal losses when using each control structure in such converters has been studied as well.......Current control based on hysteresis algorithms are widely used in different applications, such as motion control, active filtering or active/reactive power delivery control in distributed generation systems. The hysteresis current control provides to the system a fast and robust dynamic response......, and requires a simple implementation in standard digital signal platforms. On the other hand, the main drawback of classical hysteresis current control lies in the fact that the switching frequency is variable, as the hysteresis band is fixed. In this paper a variable band hysteresis control algorithm...
The Influence of phase-locked loop on the stability of single-phase grid-connected inverter
DEFF Research Database (Denmark)
Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede
2015-01-01
admittance of single-phase current-controlled inverters with different grid stiffness is analyzed in this paper. It shows that the PLL introduces a negative paralleled admittance into the output admittance of the inverter, which may lead to unintentional low-order harmonic oscillation in a weak grid...... for avoiding the PLL induced instability in single-phase inverters. At last the relationship between PLL bandwidth and the Short Circuit Ratio (SCR) of the grid has been derived to guide the design of the PLL. Experimental results are presented in order to verify this analysis, and the resonant frequencies can...... be predicted by the method. The possible instability due to different PLL bandwidth is also demonstrated....
Directory of Open Access Journals (Sweden)
A. Nouaiti
2018-02-01
Full Text Available This paper presents the design and the implementation of a low-cost single phase five-level inverter for photovoltaic applications. The proposed multilevel inverter is composed of a simple boost converter, a switched-capacitor converter, and an H-bridge converter. An efficient control method which associates a closed-loop regulation method with a simple maximum power point tracking (MPPT method is applied in order to allow the proposed multilevel inverter to transfer power energy from solar panels to autonomous load with no storage batteries. An experimental prototype of this inverter is fabricated at the laboratory and tested with a digital control system. Obtained results confirm the simplicity and the performance of the proposed photovoltaic system.
International Nuclear Information System (INIS)
Hamid, Muhammad Imran; Jusoh, Awang
2014-01-01
Highlights: • A reduction scheme for harmonics from utility interactive PV-inverter is proposed. • Single-phase conditioner with 3-phase expandability structure is used. • The single-phase conditioner in 3-phase structure work independently. • The scheme works effectively within overall operation range of the PV-inverter. • Conditioner in the scheme also improves the PV-inverter and plant’s utility factor. - Abstract: As the natural behavior of energy source and design characteristic, the current generated by a grid-interactive PV-inverter may contain harmonics. This distortion component will be carried on from the PV-inverter during injection power into the grid. Excessive harmonics in a grid will lead to a variety of power quality problems. This paper presents a distortion reduction scheme, utilizing a fed forward single-phase, generation-side power conditioner with a structure that can be expanded for use in a three-phase system and can work independently under imbalanced condition. Conditioner is placed in parallel with the photovoltaic plant and it functions to compensate the plant’s output current distortion, so that the total current flow to the grid is sinusoidal. This method also includes the implementation of a simpler control system for the conditioner, which consists of a combination of distortion current extraction, synchronization and a current control system, and realized through a TMS320F28335: a 150 MHz floating point DSP controller. Testing of the conditioner prototype, which was conducted on a real operation of a PV plant, showed that the scheme worked effectively within the overall operation range of the PV plant. This paper also discusses the potential of utility factor improvement of the PV-inverter and plant due to implementation of conditioner in the scheme
DEFF Research Database (Denmark)
Dai, Ning-Yi; Zhang, Wen-Chen; Wong, Man-Chung
2015-01-01
This study proposes a capacitive-coupling grid-connected inverter (CGCI), which consists of a full-bridge single-phase inverter coupled to a power grid via one capacitor in series with an inductor. The fundamental-frequency impedance of the coupling branch is capacitive. In contrast...... reactive power at an operational voltage much lower than that of the IGCI. This reduces the system's initial cost and operational losses, as well as the energy stored in the DC-link capacitor. The CGCI has been analysed and a DC voltage selection method is proposed. Using this method, the DC-link voltage...
Almasoudi, Fahad M.; Alatawi, Khaled S.; Matin, Mohammad
2017-08-01
Implementation of transformerless inverters in PV grid-tied system offer great benefits such as high efficiency, light weight, low cost, etc. Most of the proposed transformerless inverters in literature are verified for only real power application. Currently, international standards such as VDE-AR-N 4105 has demanded that PV grid-tied inverters should have the ability of controlling a specific amount of reactive power. Generation of reactive power cannot be accomplished in single phase transformerless inverter topologies because the existing modulation techniques are not adopted for a freewheeling path in the negative power region. This paper enhances a previous high efficiency proposed H6 trnasformerless inverter with SiC MOSFETs and demonstrates new operating modes for the generation of reactive power. A proposed pulse width modulation (PWM) technique is applied to achieve bidirectional current flow through freewheeling state. A comparison of the proposed H6 transformerless inverter using SiC MOSFETs and Si MOSFTEs is presented in terms of power losses and efficiency. The results show that reactive power control is attained without adding any additional active devices or modification to the inverter structure. Also, the proposed modulation maintains a constant common mode voltage (CM) during every operating mode and has low leakage current. The performance of the proposed system verifies its effectiveness in the next generation PV system.
Directory of Open Access Journals (Sweden)
Tofael Ahmed
2014-06-01
Full Text Available In this paper, a single phase doubly grounded semi-Z-source inverter with maximum power point tracking (MPPT is proposed for photovoltaic (PV systems. This proposed system utilizes a single-ended primary inductor (SEPIC converter as DC-DC converter to implement the MPPT algorithm for tracking the maximum power from a PV array and a single phase semi-Z-source inverter for integrating the PV with AC power utilities. The MPPT controller utilizes a fast-converging algorithm to track the maximum power point (MPP and the semi-Z-source inverter utilizes a nonlinear SPWM to produce sinusoidal voltage at the output. The proposed system is able to track the MPP of PV arrays and produce an AC voltage at its output by utilizing only three switches. Experimental results show that the fast-converging MPPT algorithm has fast tracking response with appreciable MPP efficiency. In addition, the inverter shows the minimization of common mode leakage current with its ground sharing feature and reduction of the THD as well as DC current components at the output during DC-AC conversion.
Modeling Single-Phase PV HB-ZVR Inverter Connected to Grid
DEFF Research Database (Denmark)
Guo, Yougui; Zeng, Ping; Zhu, Jieqiong
2011-01-01
PLECS is used to model the PV H-bridge zero voltage rectifier (HB-ZVR) inverter connected to grid and good results are obtained. First, several common topologies of PV inverters are introduced. Then the unipolar PWM control strategy is described for PV HB-ZVR inverter. Third, PLECS is briefly...... introduced. Fourth, the modeling of PV HB-ZVR inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is very powerful tool to real power circuits and it is very easy to simulate LCL filter. They have also verified that the unipolar PWM control...... strategy is feasible to control the PV HB-ZVR inverter....
Highly efficient GaN HEMTs transformer-less single-phase inverter for grid-tied fuel cell
Alatawi, Khaled; Almasoudi, Fahad; Matin, Mohammad
2017-08-01
Transformer-less inverters are the most efficient approach to utilize renewable energy sources for grid tied applications. In this paper, a grid-tied fuel cell transformer-less single-phase inverter equipped with GaN HEMTs is proposed. The new topology is derived from conventional H5 inverter. The benefits of using GaN HEMTs are to enable the system to switch at high frequency, which will reduce the size, volume and cost of the system. Moreover, inverter control is designed and proposed to supply real power to the grid and to work as DSTATCOM to mitigate any voltage sag and compensate reactive power in the system. A comparison of the performance of the proposed inverter with Si IGBT and GaN HEMTs was presented to analyze the benefits of using WBG devices. The switching strategy of the new topology creates a new current path which reduces the conduction losses significantly. The analysis of the proposed system was carried out using MATLAB/SIMULINK and PSIM and the results show that the proposed controller improves voltage stability, power quality, mitigates voltage sag and compensates reactive power. Accordingly, the results prove the effectiveness of the system for grid-tied applications.
DEFF Research Database (Denmark)
Monfared, Mohammad; Golestan, Saeed; Guerrero, Josep M.
2014-01-01
Control of three-phase power converters in the synchronous reference frame is now a mature and well developed research topic. However, for single-phase converters, it is not as well-established as three-phase applications. This paper deals with the design of a synchronous reference frame multi......-loop control strategy for single phase inverter-based islanded distributed generation (DG) systems. The proposed controller uses a synchronous reference frame PI (SRFPI) controller to regulate the instantaneous output voltage, a capacitor current shaping loop in the stationary reference frame to provide active...... in the synchronous reference frame, it is not straightforward to fine-tune the control parameters and evaluate the stability of the whole closed loop system. To overcome this problem, the stationary reference frame equivalent of the voltage loop is derived. Then, a step-by-step systematic design procedure based...
Stability boundary analysis in single-phase grid-connected inverters with PLL by LTP theory
Salis, Valerio; Costabeber, Alessando; Cox, Stephen M.; Zanchetta, Pericle; Formentini, Andrea
2017-01-01
Stability analysis of power converters in AC net¬works is complex due to the non-linear nature of the conversion systems. Whereas interactions of converters in DC networks can be studied by linearising about the operating point, the extension of the same approach to AC systems poses serious challenges, especially for single-phase or unbalanced three-phase systems. A general method for stability analysis of power converters suitable for single-phase or unbalanced AC networks is presented in th...
LLCL-Filter Based Single-Phase Grid-Tied Aalborg Inverter
DEFF Research Database (Denmark)
Wu, Weimin; Feng, Shuangshuang; Ji, Junhao
2014-01-01
The Aalborg Inverter is a new type of high efficient DC/AC grid-tied inverter, where the input DC voltage can vary in a wide range. Compared with the LCL-filter, the LLCL-filter can save the total inductance for the conventional voltage source inverter. In this paper, an LLCL-filter based Aalborg...... Inverter is proposed and its character is illustrated through the small signal analysis in both “Buck” and “Buck-Boost” mode. From the modeling, it can be seen that the resonant inductor in the capacitor loop has not brought extra control difficulties, whereas more inductance in the power loop can be saved....... Simulation and experiments are carried out to verify the analysis and the design through an 220 V/50 Hz, 2000 W prototype....
Photovoltaic power system tests on an 8-kilowatt single-phase line-commutated inverter
Stover, J. B.
1978-01-01
Efficiency and power factor were measured as functions of solar array voltage and current. The effects of input shunt capacitance and series inductance were determined. Tests were conducted from 15 to 75 percent of the 8 kW rated inverter input power. Measured efficiencies ranged from 76 percent to 88 percent at about 50 percent of rated inverter input power. Power factor ranged from 36 percent to 72 percent.
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
Future photovoltaic (PV) inverters are expected to comply with more stringent grid codes and reliability requirements, especially when a high penetration degree is reached, and also to lower the cost of energy. A junction temperature control concept is proposed in this study for the switching......, allowing an optimal design of the proposed control scheme with controlled mean junction temperature and reduced junction temperature swings. The effectiveness of the control method in terms of both thermal performance and electrical performance is validated by the simulations and experiments, respectively....... Both test results show that single-phase PV inverters with the proposed control approach not only can support the grid voltage recovery in low-voltage ride-through operation but also can improve the overall reliability with a reduced junction temperature....
Directory of Open Access Journals (Sweden)
Borkowski Dariusz
2016-01-01
Full Text Available Single-phase grid connected inverters are nowadays broadly developed and tested in various types of applications especially in photovoltaic systems. The main aim of the inverter control strategy is to extract the maximum energy from the PV system which corresponds to the maximum power at certain conditions. However, the MPPT methods are also important in other renewable energy conversion systems. This paper analyses the performance of a commercially available photovoltaic inverter in water and wind systems. Presented models are implemented in a laboratory test bench in the form of torque characteristics realised by an induction motor fed by the inverter with vector control. The parameters are scaled into relative variables to provide a proper performance comparison. Presented tests include step response to assess the performance of a system dynamic. The dynamic tests showed a fast response of the investigated systems. The MPPT tracking accuracy tested under realistic profiles is similar for both cases: 98% and 96% respectively for the wind and water systems. These results prove the satisfactory performance of the MPPT of the PV microinverter in these applications.
Investigation on stacked cascade multilevel inverter by employing single-phase transformers
Directory of Open Access Journals (Sweden)
Y. Suresh
2016-06-01
Full Text Available In the present paper a new version of multilevel inverter is investigated. This new version is based on hybrid association of commutation cells with H-bridge cells. The association allows a significant reduction of the volume of the capacitors. In fact, presented topology allows us to work on higher input voltage levels with the same power switches. This new version is generally called as SCMI (stacked cascade multilevel inverter. The proposed inverter has potential to generate high quality waveforms, reduction in switching frequency, capable to operate at higher voltage levels and finally utilizes minimum number of switching components. The presented version of SCMI is simulated in Matlab-simulink and further, experimental validation is carried out in the laboratory with prototype setup.
Leakage current analysis of single-phase transformer-less grid-connected PV inverters
DEFF Research Database (Denmark)
Ma, Lin; Kerekes, Tamas; Teodorescu, Remus
2015-01-01
Transformer-less string PV inverter is getting more and more widely utilized due to its higher efficiency, smaller volume and weight. However, without the galvanic isolation, the leakage current limitation and operation safety became the key issues of transformer-less inverters. This paper...... simplifies the leakage current generation circuit model and presents a leakage current estimation method both in real time and frequency domain. It shows that the leakage current is related to the circuit stray parameters, output filter and common mode voltage. Furthermore, with the proposed analysis method......, the leakage current generation of H-bridge with different modulation methods and HERIC inverter are discussed individually. At last, the presented method has been verified via simulation....
Improved Reliability of Single-Phase PV Inverters by Limiting the Maximum Feed-in Power
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
. The CPG control strategy is activated only when the DC input power from PV panels exceeds a specific power limit. It enables to limit the maximum feed-in power to the electric grids and also to improve the utilization of PV inverters. As a further study, this paper investigates the reliability performance...... of the power devices (e.g. IGBTs) used in PV inverters with the CPG control under different feed-in power limits. A long-term mission profile (i.e. solar irradiance and ambient temperature) based stress analysis approach is extended and applied to obtain the yearly electrical and thermal stresses of the power...
Directory of Open Access Journals (Sweden)
Renke Han
2014-01-01
Full Text Available It is a very crucial problem to make a microgrid operated reasonably and stably. Considering the nonlinear mathematics model of inverter established in this paper, the input-output feedback linearization method is used to transform the nonlinear mathematics model of inverters to a linear tracking synchronization and consensus regulation control problem. Based on the linear mathematics model and multiagent consensus algorithm, a decentralized coordinated controller is proposed to make amplitudes and angles of voltages from inverters be consensus and active and reactive power shared in the desired ratio. The proposed control is totally distributed because each inverter only requires local and one neighbor’s information with sparse communication structure based on multiagent system. The hybrid consensus algorithm is used to keep the amplitude of the output voltages following the leader and the angles of output voltage as consensus. Then the microgrid can be operated more efficiently and the circulating current between DGs can be effectively suppressed. The effectiveness of the proposed method is proved through simulation results of a typical microgrid system.
A new high-efficiency single-phase transformerless PV inverter topology
DEFF Research Database (Denmark)
Kerekes, Tamas; Teodorescu, Remus; Rodriguez, Pedro
2011-01-01
There is a strong trend in the photovoltaic (PV) inverter technology to use transformerless topologies in order to acquire higher efficiencies combining with very low ground leakage current. In this paper a new topology, based on the H-Bridge with a new AC bypass circuit consisting in a diode...
H-Bridge Transformerless Inverter with Common Ground for Single-Phase Solar-Photovoltaic System
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede
2017-01-01
IGBT's (RB-IGBT) and two MOSFET's), a capacitor and a small filter at the output stage. The proposed topology share a common ground with the grid and the PV source. A Unipolar Sinusoidal Pulse-Width Modulation (SPWM) technique is used to modulate the inverter to minimize switching loss, output current...
2016-09-01
control system to achieve maximum efficiency and battery life extension. Various methods, including the use of fuzzy logic control [13], inner-loop...to control the direction of power flow between the AC grid and the HESS. Figure 9. H-Bridge Inverter Schematic C Rsc + - vac To loads 14 (2...Figure 23. EMS Simulation Configurable Boost Controller – SC Bank Connected with BPF c . SC Bank Connected with 120-Hz BPF and LPF While the 120-Hz
System and method for single-phase, single-stage grid-interactive inverter
Liu, Liming; Li, Hui
2015-09-01
The present invention provides for the integration of distributed renewable energy sources/storages utilizing a cascaded DC-AC inverter, thereby eliminating the need for a DC-DC converter. The ability to segment the energy sources and energy storages improves the maintenance capability and system reliability of the distributed generation system, as well as achieve wide range reactive power compensation. In the absence of a DC-DC converter, single stage energy conversion can be achieved to enhance energy conversion efficiency.
Application of PI Current Controller in Single Phase Inverter System Connected to Non Linear Load
Chai Anak Ajot, Tracy; Salimin, Suriana; Aziz, Roziah
2017-08-01
This study is concerned with the problem of network power quality when inverter systems are connected to a nonlinear load. Nonlinear loads are well known as one of the biggest source of harmonics in the power system. Besides that, inverter systems also have their nonlinearity characteristic because of the electronic components. As the inverter system is connected to nonlinear load, it resulting in harmonic distortion-related problem and draw non-sinusoidal currents in the system, thus reducing the power quality in the system. The application of Proportional Integral controller in this system is the main interest of this study. This current controller capable of reducing total harmonic distortion and improve the state of current waveform. This paper focuses on application of simple manual trial and error tuning technique to produce the optimum value for the gains. The result of study verifies the trial and error manual tuning of PI current controller in compensating harmonic distortions. Simulation and modelling of the system are successfully developed using Matlab/Simulink.
High Performance ZVT with Bus Clamping Modulation Technique for Single Phase Full Bridge Inverters
Energy Technology Data Exchange (ETDEWEB)
Xia, Yinglai; Ayyanar, Raja
2016-03-20
This paper proposes a topology based on bus clamping modulation and zero-voltage-transition (ZVT) technique to realize zero-voltage-switching (ZVS) for all the main switches of the full bridge inverters, and inherent ZVS and/or ZCS for the auxiliary switches. The advantages of the strategy include significant reduction in the turn-on loss of the ZVT auxiliary switches which typically account for a major part of the total loss in other ZVT circuits, and reduction in the voltage ratings of auxiliary switches. The modulation scheme and the commutation stages are analyzed in detail. Finally, a 1kW, 500 kHz switching frequency inverter of the proposed topology using SiC MOSFETs has been built to validate the theoretical analysis. The ZVT with bus clamping modulation technique of fixed timing and adaptive timing schemes are implemented in DSP TMS320F28335 resulting in full ZVS for the main switches in the full bridge inverter. The proposed scheme can save up to 33 % of the switching loss compared with no ZVT case.
Directory of Open Access Journals (Sweden)
UNLU, M.
2015-05-01
Full Text Available A simple power electronic interface based on the line-commutated inverter (LCI has been developed in order to inject sinusoidal current to the grid for single-phase grid-connected photovoltaic (PV energy generation systems. The proposed inverter facilitates controlling the injecting/grid current with a controllable power factor in contrast to the conventional LCI system. It is achieved that the total harmonic distortion (THD of the injecting currents for the different firing angles/power factors and reference currents is about 5% or less than 5%. Thus, the grid-connected standards for injecting current are satisfied without filter equipment unlike the conventional LCI system. The proposed system has been built in MATLAB/Simulink and examined experimentally on PV array of 160 W. The simulation and experimental results are better performance than the conventional line-commutated inverter methods reported in the literature. The proposed LCI has a simple and robust structure, and it can be easily synchronized with grid thanks to self-latching property of SCRs. Therefore, it is a good alternative for the power transferring from PV panels to the utility grid in grid-connected PV systems.
DEFF Research Database (Denmark)
Ji, Junhao; Wu, Weimin; He, Yuanbin
2015-01-01
The single-phase power converter topologies evolving of photovoltaic applications are still including passive filters, like the LCLor LLCL-filter. Compared with the LCL-filter, the total inductance of the LLCL-filter can be reduced a lot. However, due to the resonant inductor in series...... with the bypass capacitor, the differential mode (DM) electromagnetic interference (EMI) noise attenuation of an LLCL-filter-based grid-tied inverter declines. Conventionally, a capacitor was inserted in parallel with the LC resonant circuit branch of the LLCL-filter to suppress the DM EMI noise. In order...... to achieve a small value of capacitor as well as to minimize the additional reactive power, a novel simple DM EMI suppressor for the LLCL-filter-based system is proposed. The characters of two kinds of DM EMI suppressor are analyzed and compared in detail. Simulations and experiments on a 0.5-kW 110-V/50-Hz...
DEFF Research Database (Denmark)
Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil
2017-01-01
, nowadays these systems should have Low Voltage Ride-Through (LVRT) capability. The PV system should stay connected to the grid at fault time and help to recover the grid voltage by injecting the reactive power like in a power plant or a custom power device. There are two important factors for single phase...... grid connected PV inverters. The first one is the structure of the inverter and the second one is the control part. In this regard, the HERIC inverter can be a good selection among the transformerless inverters for a PV system due to its high efficiency. For the control part, this paper presents a look...
Zhang, Hao; Ding, Honghui; Yi, Chuanzhi
2017-06-01
This paper deals with the design-oriented analysis of slow-scale bifurcations in single phase DC-AC inverters. Since DC-AC inverter belongs to a class of nonautonomous piecewise systems with periodic equilibrium orbits, the original averaged model has to be translated into an equivalent autonomous one via a virtual rotating coordinate transformation in order to simplify the theoretical analysis. Based on the virtual equivalent model, eigenvalue sensitivity is used to estimate the effect of the important parameters on the system stability. Furthermore, theoretical analysis is performed to identify slow-scale bifurcation behaviors by judging in what way the eigenvalue loci of the Jacobian matrix move under the variation of some important parameters. In particular, the underlying mechanism of the slow-scale unstable phenomenon is uncovered and discussed thoroughly. In addition, some behavior boundaries are given in the parameter space, which are suitable for optimizing the circuit design. Finally, physical experiments are performed to verify the above theoretical results.
DEFF Research Database (Denmark)
Han, Yang; Jiang, Ai-Ting; Coelho, Ernane A. A.
2018-01-01
The dual-loop control strategies in hybrid reference frame (HRF) for single-phase voltage source inverters (VSIs) in islanded operation mode is studied, which applies a capacitor voltage shaping loop in the synchronous reference frame (SRF) and a capacitor current shaping loop in the stationary r...
DEFF Research Database (Denmark)
Boora, Arash A.; Nami, Alireza; Zare, Firuz
2010-01-01
of the load is close to unity. In this paper, a new single-inductor multi-output dc/dc converter is proposed that can control the dc-link voltages of a single-phase diode-clamped inverter asymmetrically to achieve voltage quality enhancement. The circuit of the presented converter is explained and the main...
A New Design Method for the Passive Damped LCL and LLCL Filter-Based Single-Phase Grid-Tied Inverter
DEFF Research Database (Denmark)
Wu, Weimin; He, Yuanbin; Tang, Tianhao
2013-01-01
A higher order passive power filter (LLCL filter) for the grid-tied inverter is becoming attractive for industrial applications due to the possibility to reduce the cost of the copper and the magnetic material. However, similar to the conventional LCL filter, the grid-tied inverter is facing....... All these are verified through the experiments on a 2-kW single-phase grid-tied inverter prototype using proportional resonant controllers. It is concluded that, compared with the LCL filter, the proposed passive damped LLCL filter can not only save the total filter inductance and reduce the volume...... control challenges. An active or a passive damping measure can be adopted to suppress the possible resonances between the grid and the inverter. For an application with a stiff grid, a passive damping method is often preferred for its simpleness and low cost. This paper introduces a new passive damping...
Haga, Hitoshi; Takahashi, Isao; Ohishi, Kiyoshi
This paper proposes a new inverter drive system for an interior permanent magnet (IPM) synchronous motor and an inverter control strategy to obtain the unity power factor operation of the single-phase diode rectifier. The motor drive system for home appliances requires improving the input power factor without a reactor, an electrolytic capacitor and a switching device. This paper can achieve to improve the input power factor without a reactor, a current control-switching converter and an electrolytic capacitor. The proposed system consists of only single-phase diode rectifier, small film capacitor (10uF/kW) across the dc-bus, three-phase inverter and IPM motor. Source side energy provides directly to the motor without smoothing the dc-bus voltage. There are many ripple voltages across the dc-bus. A principle of unity-power-factor operation is that the inverter makes the waveform of input current sinusoidal. The unity power factor operation is achieved by dither effect. For IPM motor, the inverter control scheme in this paper is based on direct torque control (DTC). The proposed system is constructed by the input current controller based on DTC. The additional current controller improves its input current waveform. This paper describes that the proposed method achieves the power factor 98.8% by experimental tests.
DEFF Research Database (Denmark)
Qin, Zian; Tang, Yi; Loh, Poh Chiang
2015-01-01
studied, where the commercially available film capacitors, circuit topologies, and control strategies for active power decoupling are all taken into account. Then, an adaptive decoupling voltage control method is proposed to further improve the performance of dc decoupling in terms of efficiency...... and reliability. The feasibility and superiority of the identified solution for active power decoupling together with the proposed adaptive decoupling voltage control method are finally verified by both the experimental results obtained on a 2 kW single-phase inverter.......This paper presents the benchmark study of ac and dc active power decoupling circuits for second-order harmonic mitigation in kW-scale single-phase inverters. First of all, the best solutions of active power decoupling to achieve high efficiency and power density are identified and comprehensively...
DEFF Research Database (Denmark)
Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
, especially at night when there is no solar irradiance. This serves as a motivation for utilizing the PV inverters at night for reactive power compensation. Thus, an analysis on the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance and the reliability has...... at night, the impact of PV sites on the economic value of the inverter is assessed. This analysis can be useful in choosing between conventional reactive power compensation devices or PV inverters for injecting reactive power to the grid....
DEFF Research Database (Denmark)
Yao, Wenli; Wang, Xiongfei; Loh, Poh Chiang
2017-01-01
the intention of this paper to quantify ac and dc imperfections experienced by the differential inverter when storage mismatch occurs. A simple improved scheme is then proposed for raising performance of the differential inverter (or the differential rectifier where desired). Simulation and experimental results...
Comparative Analysis of Si- and GaN-Based Single-Phase Transformer-Less PV Grid-Tied Inverter
Directory of Open Access Journals (Sweden)
Khaled Alatawi
2018-03-01
Full Text Available Recently, the interest in grid-tied PV transformer-less inverters has increased rapidly, because of their higher efficiency and lower cost compared to traditional line transformer inverters. This paper presents a new modified transformer-less topology derived from H5 inverter, and provides a detailed comparison between the use of GaN and Si devices for the proposed topology. Detailed operation modes, inverter structure and switching strategy of the proposed topology are presented. Datasheet information, conduction losses, switching losses, and heat sink requirements are studied and analyzed to provide an accurate comparison between GaN and Si power devices for the proposed topology operating at unity power factor. The results show that, GaN power devices significantly reduce the power losses in the system, which consequently allow a significant increase in either inverter power rating or switching frequency. Thus, the use of GaN power devices for the proposed inverter can be more appealing and cost-effective approach.
A PWM Controller of a Full Bridge Single-Phase Synchronous Inverter for Micro-Grid System
Rahman, Tawfikur; Motakabber, S. M. A.; Ibrahimy, M. I.; Raghib, Aliza ‘Aini Binti Md Ralib@ Md
2017-12-01
Nowadays, microgrid system technology is becoming popular for small area power management systems. It is essential to be less harmonic-distortion and high efficiency of the inverter for microgrid applications. Pulse width modulation (PWM) controller is a conventional switching control technique which is suitable to use in the microgrid connected power inverter system. The control method and algorithm of this technique are challenging, and different approaches are required to avoid the complexity for a customized solution of the microgrid application. This paper proposes a comparative analysis of different controller and their operational methods. A PWM controller is used to reduce the ripple voltage noise while a continuous current mode provides a small output ripple which gives steady-state error as zero on fundamental and cutoff frequency. To reduce the ripple current, higher frequency harmonic distortion, switching loss and phase noise, LC low pass filter is used on either side of input and output terminals. The proposed inverter is designed by MATLAB 2016a simulation software. A balanced load resistance (RL = 20.5 Ω) of star configuration and a dual input DC voltage of ± 35V are considered. In this design, the circuit parameters, the fundamental frequency of 50 Hz, the PWM duty cycle of 95%, the cutoff frequency of the switching controller of 33 kHz are considered. The inverter in this paper exhibits THD of 0.44% and overall efficiency approximately of 98%. The proposed inverter is expected to be suitable for microgrid applications.
DEFF Research Database (Denmark)
Zhang, Zhen; Yang, Yongheng; Blaabjerg, Frede
2016-01-01
With the fast development in Photovoltaic (PV) technology, the relevant grid-connection requirements/standards are continuously being updated, and more challenges have been imposed on both single-phase and three-phase grid-connected PV systems. For instance, PV systems are currently required...... to remain connected under grid voltage sags (even zero voltage condition). In this case, much attention should be paid to the grid synchronization in such a way to properly ride-through grid faults. Thus, in this paper, the most commonly-used and recently-developed Phase Locked Loop (PLL) synchronization...... methods have been evaluated for single-phase grid-connected PV systems in the case of Zero-Voltage Ride-Through (ZVRT) operation. The performances of the prior-art PLL methods in response to zero voltage faults in terms of detection precision and dynamic response are assessed in this paper. Simulation...
DEFF Research Database (Denmark)
Wickramasinghe Abeywardana, Damith Buddika; Acuna, Pablo; Hredzak, Branislav
2018-01-01
Vehicle to grid (V2G) reactive power compensation using electric vehicle (EV) onboard chargers helps to ensure grid power quality by achieving unity power factor operation. However, the use of EVs for V2G reactive power compensation increases the second-order harmonic ripple current component......-side capacitor without adversely affecting the EV battery. The operation of the boost inverter-based EV charger with second-order harmonic and switching frequency ripple current reduction, the dynamic behavior of the system, the transition between different operating modes, the DC-side capacitor voltage control...
DEFF Research Database (Denmark)
Wang, Wen; Yan, Lingjie; Zeng, Xiangjun
2017-01-01
Neutral-to-ground overvoltage may occur in non-effectively grounded power systems because of the distributed parameters asymmetry and resonance between Petersen coil and distributed capacitances. Thus, the constraint of neutral-to-ground voltage is critical for the safety of distribution networks....... In this paper, an active grounding system based on single-phase inverter and its control parameter design method is proposed to achieve this objective. Relationship between its output current and neutral-to-ground voltage is derived to explain the principle of neutral-to-ground voltage compensation. Then...... margin subjecting to large range of load change. The PI method is taken as the comparative method and the performances of both control methods are presented in detail. Experimental results prove the effectiveness and novelty of the proposed grounding system and control method....
DEFF Research Database (Denmark)
Qin, Zian; Tang, Yi; Loh, Poh Chiang
2016-01-01
efficiency and high power density is identified and comprehensively studied, and the commercially available film capacitors, the circuit topologies, and the control strategies adopted for active power decoupling are all taken into account. Then, an adaptive decoupling voltage control method is proposed...... to further improve the performance of dc decoupling in terms of efficiency and reliability. The feasibility and superiority of the identified solution for active power decoupling together with the proposed adaptive decoupling voltage control method are finally verified by both the simulation and experimental......This paper presents the benchmark study of ac and dc active power decoupling circuits for second order harmonic mitigation in kW scale single-phase inverters. First of all, a brief comparison of recently reported active power decoupling circuits is given, and the best solution that can achieve high...
DEFF Research Database (Denmark)
Zhang, Zhen; Yang, Yongheng; Blaabjerg, Frede
2017-01-01
With the fast development of distributed power generations, stability and security have attracted extensive attention in the recent years. As a representative of clean energies, Photovoltaic (PV) systems have been installed extensively worldwide. This drives grid-connected requirements to be cont......With the fast development of distributed power generations, stability and security have attracted extensive attention in the recent years. As a representative of clean energies, Photovoltaic (PV) systems have been installed extensively worldwide. This drives grid-connected requirements......-connected single-stage single-phase PV systems in the case of Low/Zero Voltage Ride-Through (LVRT/ZVRT) operation. A comparative analysis of the two LVRT/ZVRT control methods for PV systems is presented. Simulation results are presented, which verifies that the LVRT/ZVRT methods can help the PV systems...... to temporarily ride-through the grid low-/zero-voltage faults. The power phase-angle control method has a better dynamic response....
Leakage current analysis of a single-phase transformer-less PV inverter connected to the grid
DEFF Research Database (Denmark)
Ma, Lin; Tang, F.; Zhou, F.
2009-01-01
the PV array and the ground. It is quite harmful to the body safety and PV system. In order to avoid leakage current, different inverter topologies that generate no varying common-mode voltages, such as bipolar pulse-width modulation (PWM) full-bridge topology, NPC topology have been proposed. From...... the safety and energy saving viewpoint, it is necessary to develop a higher efficiency topology. In this paper, the generation mechanism of common mode current is discussed. Then different methods used to eliminate the leakage current are compared. Finally, the full-bridge which generates no varying common......Due to the large surface of the PV generator, its stray capacity with respect to the ground reaches values that can be quite high. When no transformer is used in a grid-connected PV system, common-mode current, which caused by the common mode voltage, can flow through the stray capacitance between...
Directory of Open Access Journals (Sweden)
Jianke Li
2014-01-01
Full Text Available Compared with L-type filter, LCL-type filter is more suitable for high-power low-switching frequency applications with reducing the inductance, improving dynamic performance. However, the parameter design for the LCL filter is more complex due to the influence of the controller response performance of the converter. If the harmonic current around switching frequency can be fully suppressed, it is possible for inverter to decrease the total inductance as well as the size and the cost. In this paper, the model of the LCL filter is analyzed and numerical algorithms are adopted to analyze the stability of the closed-loop control system and stable regions are deduced with different parameters of LCL filter. Then, the minimum sampling frequencies are deduced with different conditions. Simulation and experimental results are provided to validate the research on the generating mechanism for the unstable region of sampling frequency.
Hashino, Satoshi; Wada, Keiji; Shimizu, Toshihisa
Power supplies used on the electric power environment test process for electronic products and audio-amplifiers are required to generate arbitrary ac voltage waveforms in the wide frequency range. Traditionally, analogue amplifier technologies have been used for those application even though those have the disadvantages of low-efficiency, bulky in volume, and heavy in weight. Recently, however, research on the arbitrary waveform power generator becomes to be attractive among power electronics engineers, because the audio amplifiers utilizes the D-Mode switching technologies have been move into the market. This paper presents an arbitrary ac power generator utilizes a novel instantaneous waveform control method for a single-phase voltage source PWM inverter. A remarkable feature of this control method is that an adaptive frequency band-pass filter based on a rotation frame transformation and a command generator on the rotation frame is used. The proposed method can suppress the resonance caused by the LC filter at the output line, and hence it enables to generate a rectangular voltage waveform without overshoot. The command generator generates both an instantaneous frame angle and accurate voltage commands on the rotating frame from one an analogue signal. The effectiveness of this method is verified through 500W experimental set-up.
DEFF Research Database (Denmark)
Tang, Y.; Yao, W.; Blaabjerg, Frede
2015-01-01
In single-phase uninterruptible power supply (UPS) applications, it is well known that the AC side instantaneous power is not constant by nature. The resulting input current from the DC source side will inevitably contain low frequency ripple components that may largely deteriorate the system per...
Sotoodeh, Pedram
This dissertation presents the design of a novel multi-level inverter with FACTS capability for small to mid-size (10-20kW) permanent-magnet wind installations using modular multi-level converter (MMC) topology. The aim of the work is to design a new type of inverter with D-STATCOM option to provide utilities with more control on active and reactive power transfer of distribution lines. The inverter is placed between the renewable energy source, specifically a wind turbine, and the distribution grid in order to fix the power factor of the grid at a target value, regardless of wind speed, by regulating active and reactive power required by the grid. The inverter is capable of controlling active and reactive power by controlling the phase angle and modulation index, respectively. The unique contribution of the proposed work is to combine the two concepts of inverter and D-STATCOM using a novel voltage source converter (VSC) multi-level topology in a single unit without additional cost. Simulations of the proposed inverter, with 5 and 11 levels, have been conducted in MATLAB/Simulink for two systems including 20 kW/kVAR and 250 W/VAR. To validate the simulation results, a scaled version (250 kW/kVAR) of the proposed inverter with 5 and 11 levels has been built and tested in the laboratory. Experimental results show that the reduced-scale 5- and 11-level inverter is able to fix PF of the grid as well as being compatible with IEEE standards. Furthermore, total cost of the prototype models, which is one of the major objectives of this research, is comparable with market prices.
DEFF Research Database (Denmark)
Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
there is no solar irradiance. However, reactive power injection causes additional power losses in the switching components leading to a temperature rise in the devices. Thus, this paper analyses the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance...... of their power switching components. A thermal analysis based on the mission profile (i.e., solar irradiance and ambient temperature) has been incorporated, so as to determine the additional temperature rise in the components induced by the operation outside feed-in hours. An analytical lifetime model has been...... used. The damage produced on the transistors has been quantified using Palmgren Miner rule. A reliability analysis has been carried out on a PV inverter with and without the injection of reactive power into the utility grid at nights. Economic impacts of injecting reactive power from PV inverters...
DEFF Research Database (Denmark)
Liu, Yuan; Wu, Weimin; Li, Yun
2016-01-01
. In this paper, a low pass filter is proposed to be inserted in the capacitor current feedback loop op LLCL-filter based grid-tied inverter together with a digital proportional and differential compensator. The detailed theoretical analysis is given. For verification, simulations on a 2kW/220V/10kHz LLCL......The capacitor-current-feedback active damping method is attractive for high-order-filter-based high power grid-tied inverter when the grid impedance varies within a wide range. In order to improve the system control bandwidth and attenuate the high order grid background harmonics by using the quasi...
DEFF Research Database (Denmark)
Qu, Hao; Yang, Xijun; Guo, Yougui
2014-01-01
Single-phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). Single-phase VSC...
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez
2017-01-01
Single-phase phase-locked loops (PLLs) are popular for the synchronization and control of single-phase gridconnected converters. They are also widely used for monitoring and diagnostic purposes in the power and energy areas. In recent years, a large number of single-phase PLLs with different...... structures and properties have been proposed in the literature. The main aim of this paper is to provide a review of these PLLs. To this end, the single-phase PLLs are first classified into two major categories: 1) power-based PLLs (pPLLs), and 2) quadrature signal generation-based PLLs (QSG......-PLLs). The members of each category are then described and their pros and cons are discussed. This work provides a deep insight into characteristics of different single-phase PLLs and, therefore, can be considered as a reference for researchers and engineers....
new topology for single-phase, three-level, spwm vsi with lc filter
African Journals Online (AJOL)
level PWM inverter. However, this is not the case with single-phase PWM inverters. In these days, the popular single-phase inverters adopt the full-bridge type using approximate sinusoidal modulation technique. The output voltage in them has two values: zero and pos- itive supply dc voltage levels in the positive half cycle.
experimental implementation of single-phase, three-level, sinusoidal
African Journals Online (AJOL)
Experimental Implementation of SPWM VSI with R-L Load. 3. Figure 2: Switching pattern of the proposed single-phase, three-level PWM inverter. Figure 3: Prototype setup. (a) Power circuits for both inverters. (b) Logic and Driver circuits. Nigerian Journal of Technology. Vol. 31, No. 1, March 2012.
A simple output voltage control scheme for single phase wavelet ...
African Journals Online (AJOL)
DR OKE
Wavelet based techniques have been extensively used in various power engineering applications. Recently, wavelet has also been proposed to generate switching signal for single-phase pulse-width-modulated (PWM) dc-ac inverter. The main advantage of the wavelet modulated (WM) scheme is that a single synthesis ...
(SPWM) Voltage Source Inverter (VSI)
African Journals Online (AJOL)
The quest to achieve less-distorted dc-ac power conversion has resulted in the proliferation of many multilevel inverter configurations. This paper presents an experimental report of a simplified topology for single-phase, SPWM, three-level voltage source inverter wit R-L load. To keep the power circuit component count to a ...
A single phase photovoltaic inverter control for grid connected system
Indian Academy of Sciences (India)
Melo G and Canesin C A 2013 Evaluation of the main MPPT techniques for photovoltaic applications. IEEE Trans. Ind. Electron. 60(3): 1156–1167. [7] Jain S and Agarwal V 2007 Comparison of the perfor- mance of maximum power point tracking schemes applied to single-stage grid-connected photovoltaic systems.
Single-phase frequency converter
Baciu, I.; Cunţan, C. D.
2017-01-01
The paper presents a continuous voltage inverter - AC (12V / 230V) made with IGBT and two-stage voltage transformer. The sequence control transistors is achieved using a ring counter whose clock signal is obtained with a monostable circuit LM 555. The frequency of the clock signal can be adjustment with a potentiometer that modifies the charging current of the capacitor which causes constant monostable circuit time. Command sequence consists of 8 intervals of which 6 are assigned to command four transistors and two for the period break at the beginning and end of the sequence control. To obtain an alternation consisting of two different voltage level, two transistors will be comanded, connected to different windings of the transformer and the one connected to the winding providing lower voltage must be comanded twice. The output of the numerator goes through an inverter type MOS and a current amplifier with bipolar transistor.To achieve galvanic separation, an optocoupler will be used for each IGBT transistor, while protection is achieved with resistance and diode circuit. At the end there is connected an LC filter for smoothing voltage variations.
A control strategy for induction motors fed from single phase supply
DEFF Research Database (Denmark)
Søndergård, Lars Møller
1993-01-01
It is often required that a three-phased asynchronous motor can run at variable speed, which makes it necessary to use a three-phase inverter driven from a DC-source. Today, most inverters are driven from the network using a simple diode bridge and an electrolytic capacitor. The problem...... with the simple diode bridge and the electrolytic capacitor is that current is only drawn for short periods, which gives rise to harmonic currents in the network. For small drive systems (motor+inverter), i.e. less than 1.5 kW, a single phase network outlet is often used. The author describes a method whereby...
Inverter design for four-wire microgrids
Heredero Peris, Daniel; Pagès Giménez, Marc; Montesinos Miracle, Daniel
2015-01-01
This paper presents a PQ four quadrant four-wire three-phase inverter for microgrids integration. The inverter is based in two full-bridge IGBT modules connected in a three-phase configuration plus a threephase parallelized neutral branch. This topology is galvanically isolated through a single-phase transformer bank. The converter operates as a non-ideal voltage-controlled voltage source inverter under AC droop strategy with hot-swap capability based on a dynamic virtual impedance.
Performance analysis of new type grid-tied inverter-Aalborg Inverter
DEFF Research Database (Denmark)
Wu, Weimin; Wang, Zhen; Ji, Junhao
2014-01-01
Aalborg Inverter is a grid-tied DC/AC inverter. In order to optimize the design, its power losses are analyzed in detail, combined with a description of the single-phase operating principle and the modulation strategy. A 2 kW / 220 V experimental prototype is constructed to verify the theoretical...... analysis. It is concluded that a minimize inductance in the power loop does help the inverter to achieve the high efficiency with the good dynamic performance....
DEFF Research Database (Denmark)
Ma, Siyuan; Wang, Haoran; Tang, Junchaojie
2016-01-01
In single-phase inverters, DC-link capacitors are installed at the DC-link to buffer the ripple power between the AC side and DC side. Active decoupling methods introduce additional circuits at the DC side or AC side to partially or fully supply the ripple power. So that the demanded DC-link capa......In single-phase inverters, DC-link capacitors are installed at the DC-link to buffer the ripple power between the AC side and DC side. Active decoupling methods introduce additional circuits at the DC side or AC side to partially or fully supply the ripple power. So that the demanded DC...
Preparation of single phase molybdenum boride
International Nuclear Information System (INIS)
Camurlu, Hasan Erdem
2011-01-01
Highlights: → Formation of Mo and a mixture of molybdenum boride phases take place in preparation of molybdenum borides. → It is intricate to prepare single phase molybdenum borides. → Formation of single phase MoB from MoO 3 + B 2 O 3 + Mg mixtures has not been reported previously. → Single phase MoB was successfully prepared through a combination of mechanochemical synthesis and annealing process. - Abstract: The formation of MoB through volume combustion synthesis (VCS), and through mechanochemical synthesis (MCS) followed by annealing has been investigated. MoO 3 , B 2 O 3 and Mg were used as reactants while MgO and NaCl were introduced as diluents. Products were leached in dilute HCl solution and were subjected to X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) examinations. Mo was the major phase component in the VCS products under all the experimental conditions. Mo 2 B, MoB, MoB 2 and Mo 2 B 5 were found as minor phases. Products of MCS contained a mixture of Mo 2 B, MoB, MoB 2 and Mo. After annealing the MCS product at 1400 deg. C for 3 h, single phase α-MoB was obtained.
Single phase induction motor with starting performance
Energy Technology Data Exchange (ETDEWEB)
Popescu, M.; Demeter, E. [Research Institute for Electrical Machines, ICPE-ME, Bucharest (Romania); Navrapescu, V. [University `Politehnica` Bucharest, Electrical Engineering Faculty Splaiul Independentei, Bucharest (Romania)
1997-12-31
The paper presents problems related to a special type of single phase induction motor. The main novelty consists in the use of a conducting (aluminium casted) shell distributed on the periferic region of the rotor. As a result the starting performance, as well as the rated ones, is much improved in comparison with the conventional construction. (orig.) 4 refs.
DEFF Research Database (Denmark)
Sun, Qinfei; Guerrero, Josep M.; Jing, Tianjun
2017-01-01
An active islanding detection method based on Frequency-Locked Loop (FLL) for constant power controlled inverter in single-phase microgrid is proposed. This method generates a phase shift comparing the instantaneous frequency obtained from FLL unit with the nominal frequency to modify the reference...
Coordinated single-phase control scheme for voltage unbalance reduction in low voltage network.
Pullaguram, Deepak; Mishra, Sukumar; Senroy, Nilanjan
2017-08-13
Low voltage (LV) distribution systems are typically unbalanced in nature due to unbalanced loading and unsymmetrical line configuration. This situation is further aggravated by single-phase power injections. A coordinated control scheme is proposed for single-phase sources, to reduce voltage unbalance. A consensus-based coordination is achieved using a multi-agent system, where each agent estimates the averaged global voltage and current magnitudes of individual phases in the LV network. These estimated values are used to modify the reference power of individual single-phase sources, to ensure system-wide balanced voltages and proper power sharing among sources connected to the same phase. Further, the high X / R ratio of the filter, used in the inverter of the single-phase source, enables control of reactive power, to minimize voltage unbalance locally. The proposed scheme is validated by simulating a LV distribution network with multiple single-phase sources subjected to various perturbations.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'. © 2017 The Author(s).
DEFF Research Database (Denmark)
Huang, Min; Blaabjerg, Frede; Yang, Yongheng
2013-01-01
Traditionally, when designing an LCL-filter, a three-phase inverter is simplified as a single-phase inverter for analysis and the output phase voltage is used to calculate the inverter-side current harmonics and to design inverter-side inductor. However, for a three-phase three-wire grid-tied sys......Traditionally, when designing an LCL-filter, a three-phase inverter is simplified as a single-phase inverter for analysis and the output phase voltage is used to calculate the inverter-side current harmonics and to design inverter-side inductor. However, for a three-phase three-wire grid...
MPPT algorithm for voltage controlled PV inverters
DEFF Research Database (Denmark)
Kerekes, Tamas; Teodorescu, Remus; Liserre, Marco
2008-01-01
This paper presents a novel concept for an MPPT that can be used in case of a voltage controlled grid connected PV inverters. In case of single-phase systems, the 100 Hz ripple in the AC power is also present on the DC side. Depending on the DC link capacitor, this power fluctuation can be used...
Ground Fault Overvoltage With Inverter-Interfaced Distributed Energy Resources
Energy Technology Data Exchange (ETDEWEB)
Ropp, Michael; Hoke, Anderson; Chakraborty, Sudipta; Schutz, Dustin; Mouw, Chris; Nelson, Austin; McCarty, Michael; Wang, Trudie; Sorenson, Adam
2017-04-01
Ground Fault Overvoltage can occur in situations in which a four-wire distribution circuit is energized by an ungrounded voltage source during a single phase to ground fault. The phenomenon is well-documented with ungrounded synchronous machines, but there is considerable discussion about whether inverters cause this phenomenon, and consequently whether inverters require effective grounding. This paper examines the overvoltages that can be supported by inverters during single phase to ground faults via theory, simulation and experiment, identifies the relevant physical mechanisms, quantifies expected levels of overvoltage, and makes recommendations for optimal mitigation.
Analysis of Magnetically-Coupled Impedance Source Three-Phase Four-Switch Inverters
DEFF Research Database (Denmark)
Li, Kerui; Abdelhakim, Ahmed; Yang, Yongheng
2017-01-01
In this paper, magnetically-coupled impedance source (MCIS) three-phase four-switch inverters are introduced for renewable energy applications. This inverter utilizes two single-phase MCIS inverters to obtain a three-phase output, where less component-count is achieved in order to reduce...... the inverter volume. On the other hand, as a result of the reduced number of switches, the proposed inverter suffers from higher voltage stresses. The MCIS inverters are first reviewed. Then, the modulation and operation principle of the MCIS three-phase inverter topology are introduced before sizing...
Instability of single-phase natural circulation
International Nuclear Information System (INIS)
Xie Heng; Zhang Jinling; Jia Dounan
1997-01-01
The author has investigated the instability of single-phase flows in natural circulation loops. The momentum equation and energy equation are made dimensionless according to some definitions, and some important dimensionless parameters are gotten. The authors decomposed the mean mass flowrate and temperature into a steady solution and a small disturbance equations. Through solving the disturbance equations, the authors get the neutral stability curves. The authors have studied the effect of the two parameters which represent the ratio of buoyancy force to the friction loss in the loop on the stability of loops. The authors also have studied the effect of the difference of height between the center of heat source and the heat sink on the stability
DEFF Research Database (Denmark)
Hadjidemetriou, Lenos; Kyriakides, Elias; Yang, Yongheng
2014-01-01
An increasing amount of single-phase photovoltaic (PV) systems on the distribution network requires more advanced synchronization methods in order to meet the grid codes with respect to power quality and fault ride through capability. The response of the synchronization technique selected...... to the harmonic voltage distortion without affecting the dynamic response of the synchronization. Therefore, the accurate response of the proposed MHDC-PLL enhances the power quality of the PV inverter systems and additionally, the proper fault ride-through operation of PV systems can be enabled by the fast...
A MPPT Algorithm Based PV System Connected to Single Phase Voltage Controlled Grid
Sreekanth, G.; Narender Reddy, N.; Durga Prasad, A.; Nagendrababu, V.
2012-10-01
Future ancillary services provided by photovoltaic (PV) systems could facilitate their penetration in power systems. In addition, low-power PV systems can be designed to improve the power quality. This paper presents a single-phase PV systemthat provides grid voltage support and compensation of harmonic distortion at the point of common coupling thanks to a repetitive controller. The power provided by the PV panels is controlled by a Maximum Power Point Tracking algorithm based on the incremental conductance method specifically modified to control the phase of the PV inverter voltage. Simulation and experimental results validate the presented solution.
A low capacitance single-phase AC-DC converter with inherent power ripple decoupling
Gottardo, Davide; De Lillo, Liliana; Empringham, Lee; Costabeber, Alessando
2016-01-01
This paper proposes a new single-phase AC-DC conversion topology with inherent power ripple decoupling, based on the combination of a PWM H-bridge inverter, an AC side LC filter and a ZVS line commutated H-bridge. A capacitor on the AC side is used as power decoupling element. By appropriate selection of the capacitor voltage, the power ripple at twice the AC frequency can be cancelled from the DC side instantaneous power, achieving negligible DC voltage ripple using a smaller total capacitan...
Single-Phase Microgrid with Seamless Transition Capabilities between Modes of Operation
DEFF Research Database (Denmark)
Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril
2015-01-01
Microgrids are an effective way to increase the penetration of DG into the grid. They are capable of operating either in grid-connected or in islanded mode thereby increasing the supply reliability for the end user. This paper focuses on achieving seamless transitions from islanded to grid......-connected and vice versa for a single phase microgrid made up from voltage controlled voltage source inverters (VC-VSIs) and current controlled voltage source inverters (CC-VSIs) working together in both modes of operation. The primary control structures for the VC-VSIs and CC-VSIs is considered together...... with the secondary control loops that are used to synchronize the microgrid as a single unit to the grid. Simulation results are given that show the seamless transitions between the two modes without any disconnection times for the CC-VSIs and VC-VSIs connected to the microgrid....
Directory of Open Access Journals (Sweden)
Krishnan Arthishri
2017-05-01
Full Text Available In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT, the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.
Saltvig, Iselin; Sjøstrand, Helle; Oldenburg, Mette Holmqvist; Matzen, Steen Henrik
2016-10-17
Inverted nipples is an anatomical variation which can be uni- or bilateral, congenital or acquired. The degree of inversion can vary from slight to severe. Treatment can be surgical or non-surgical and should depend on the degree of functional problems. Non-surgical treatment can be beneficial, does not risk affecting sensibility, spares the lactiferous ducts, and therefore does not risk any interference with breast-feeding. Surgical options should only be considered when non-surgical treatment is insufficient.
DEFF Research Database (Denmark)
Liu, Xiong; Wang, Peng; Loh, Poh Chiang
2011-01-01
Single-phase stand-alone PV system is suitable for household applications in remote area. Hybrid battery/ultra-capacitor energy storage can reduce charge and discharge cycles and avoid deep discharges of battery. This paper proposes a compact seven switches structure for stand-alone PV system......-order harmonic current caused by single-phase inverter. In the proposed compact topology, a small size DC-link capacitor can achieve the same function through charging/discharging control of ultra-capacitor to mitigate second-order ripple current. Simulation results are provided to validate the effectiveness......, which otherwise needs nine switches configuration, inclusive of one switch for boost converter, four switches for single-phase inverter and four switches for two DC/DC converters of battery and ultra-capacitor. It is well-known that a bulky DC-link capacitor is always required to absorb second...
Directory of Open Access Journals (Sweden)
Luis Gerardo González-Morales
2014-01-01
Full Text Available Este artículo presenta el diseño de un sistema de conversión de energía eléctrica (SCEE para el aprovechamiento de energía solar y luego acondicionamiento e inyección de energía a la red eléctrica comercial. Se utiliza un inversor puente completo monofásico con la topología sin transformador H5 acoplado a un filtro LCL. El sistema es identificado mediante el modelo de estado promediado y de pequeña señal, el esquema de control presenta un control en cascada sintonizado mediante la asignación de polos, además de un algoritmo de seguimiento de máxima potencia de tipo perturbar y observar que permite aumentar la eficiencia del sistema, operando en el punto óptimo de funcionamiento del panel solar. En el diseño se describen aspectos técnicos fundamentales en el dimensionamiento y selección de componentes para su desarrollo experimental, así como el diseño de la estructura de control para un buen desempeño ante perturbaciones del sistema.
Onset of chaos in a single-phase power electronic inverter
DEFF Research Database (Denmark)
Avrutin, Viktor; Mosekilde, Erik; Zhusubaliyev, Zhanybai T.
2015-01-01
derived from a non-autonomous ordinary differential equation with discontinuous right-hand side. By construction, this stroboscopic map has a high number of border points. It is shown that the onset of chaos occurs stepwise, via irregular cascades of different border collisions, some of which lead...
Onset of chaos in a single-phase power electronic inverter.
Avrutin, Viktor; Mosekilde, Erik; Zhusubaliyev, Zhanybai T; Gardini, Laura
2015-04-01
Supported by experiments on a power electronic DC/AC converter, this paper considers an unusual transition from the domain of stable periodic dynamics (corresponding to the desired mode of operation) to chaotic dynamics. The behavior of the converter is studied by means of a 1D stroboscopic map derived from a non-autonomous ordinary differential equation with discontinuous right-hand side. By construction, this stroboscopic map has a high number of border points. It is shown that the onset of chaos occurs stepwise, via irregular cascades of different border collisions, some of which lead to bifurcations while others do not.
A Single Phase Seven-level Grid-connected inverter Based On Three Reference SPWM Strategy
DEFF Research Database (Denmark)
Sun, Bo; Wu, Fengjiang; Dragicevic, Tomislav
2014-01-01
This paper introduces a seven level grid connected system based on the Three Reference SPWM (TRSPWM) strategy and a Quasi PR current controller has a good output performance with a fast response and compensation for the low order harmonics in grid. With the multilevel output voltage and a high...
Directory of Open Access Journals (Sweden)
Manel Hammami
2017-12-01
Full Text Available The implementation of maximum power point tracking (MPPT schemes by the ripple correlation control (RCC algorithm is presented in this paper. A reference is made to single-phase single-stage multilevel photovoltaic (PV generation systems, when the inverter input variables (PV voltage and PV current have multiple low-frequency (ripple harmonics. The harmonic analysis is carried out with reference to a multilevel configuration consisting of an H-bridge inverter and level doubling network (LDN cell, leading to the multilevel inverter having double the output voltage levels as compared to the basic H-bridge inverter topology (i.e., five levels vs. three levels. The LDN cell is basically a half-bridge fed by a floating capacitor, with self-balancing voltage capability. The multilevel configuration introduces additional PV voltage and current low-frequency harmonics, perturbing the basic implementation of the RCC scheme (based on the second harmonic component, leading to malfunctioning. The proposed RCC algorithm employs the PV current and voltage harmonics at a specific frequency for the estimation of the voltage derivative of power dP/dV (or dI/dV, driving the PV operating point toward the maximum power point (MPP in a faster and more precise manner. The steady-state and transient performances of the proposed RCC-MPPT schemes have been preliminarily tested and compared using MATLAB/Simulink. Results have been verified by experimental tests considering the whole multilevel PV generation system, including real PV modules, multilevel insulated-gate bipolar transistor (IGBT inverters, and utility grids.
Closed-loop waveform control of boost inverter
DEFF Research Database (Denmark)
Zhu, Guo Rong; Xiao, Cheng Yuan; Wang, Haoran
2016-01-01
The input current of single-phase inverter typically has an AC ripple component at twice the output frequency, which causes a reduction in both the operating lifetime of its DC source and the efficiency of the system. In this paper, the closed-loop performance of a proposed waveform control method...... to eliminate such a ripple current in boost inverter is investigated. The small-signal stability and the dynamic characteristic of the inverter system for input voltage or wide range load variations under the closed-loop waveform control method are studied. It is validated that with the closedloop waveform...
Single-phase to three-phase power conversion interface
Wu, Jinn-Chang; Wang, Yung-Shan; Jou, Hurng-Liahng; Lu, Wei-Tso
2016-07-01
This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.
Liu, Xinrui; Zhang, Guangru; Yang, Dongsheng; Shi, Tongyu; He, Xusheng
2014-01-01
This paper is concerned with the problem of optimal control of photovoltaic grid-connected inverter. Firstly, the discrete-time nonlinear mathematical model of single-phase photovoltaic grid-connected inverter in the rotating coordinate system is constructed by the Delta operator, which simplifies the control process and facilitates direct digital realization. Then, a novel optimal control method which is significant to achieve trajectory tracking for photovoltaic grid-connected inverte...
Modelling and Simulation of Single-Phase Series Active Compensator for Power Quality Improvement
Verma, Arun Kumar; Mathuria, Kirti; Singh, Bhim; Bhuvaneshwari, G.
2017-10-01
A single-phase active series compensator is proposed in this work to reduce harmonic currents at the ac mains and to regulate the dc link voltage of a diode bridge rectifier (DBR) that acts as the front end converter for a voltage source inverter feeding an ac motor. This ac motor drive is used in any of the domestic, commercial or industrial appliances. Under fluctuating ac mains voltages, the dc link voltage of the DBR depicts wide variations and hence the ac motor is used at reduced rating as compared to its name-plate rating. The active series compensator proposed here provides dual functions of improving the power quality at the ac mains and regulating the dc link voltage thus averting the need for derating of the ac motor.
Influence of modulation method on using LC-traps with single-phase voltage source converters
DEFF Research Database (Denmark)
Wang, Xiongfei; Min, Huang; Bai, Haofeng
2015-01-01
The switching-frequency LC-trap filter has recently been employed with high-order passive filters for Voltage Source Inverters (VSIs). This paper investigates the influence of modulation method on using the LC-traps with single-phase VSIs. Two-level (bipolar) and three-level (unipolar) modulations...... that include phase distortion and alternative phase opposition distortion methods are analyzed. Harmonic filtering performances of four LC-trap-based filters with different locations of LC-traps are compared. It is shown that the use of parallel-LC-traps in series with filter inductors, either grid...... or converter side, has a worse harmonic filtering performance than using series-LC-trap in the shunt branch. Simulations and experimental results are presented for verifications....
Realization of single-phase single-stage grid-connected PV system
Directory of Open Access Journals (Sweden)
Osama M. Arafa
2017-05-01
Full Text Available This paper presents a single phase single stage grid-tied PV system. Grid angle detection is introduced to allow operation at any arbitrary power factor but unity power factor is chosen to utilize the full inverter capacity. The system ensures MPPT using the incremental conductance method and it can track the changes in insolation level without oscillations. A PI voltage controller and a dead-beat current controller are used to ensure high quality injected current to the grid. The paper investigates the system structure and performance through numerical simulation using Matlab/Simulink. An experimental setup controlled by the MicrolabBox DSP prototyping platform is utilized to realize the system and study its performance. The precautions for smooth and safe system operation including the startup sequence are fully considered in the implementation.
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede
2013-01-01
-connected PV inverters may be severely affected in different operation modes. In this paper, a detailed analysis is conducted to reveal the relationship between the harmonics level with the power factor and the current level in the PV systems. A current control solution which employs an Internal Model...... Principle (IMP) is proposed to suppress the harmonic currents injected into the grid. Experiments are carried out to verify the analysis and the performance of the proposed control method. It is demonstrated that the proposed method presents an effective solution to harmonics suppression for single......-phase grid-connected PV systems in different operation modes. Especially, it can remove higher order harmonics effectively leading to a better power quality compared to the Proportional plus Multi-Resonant Controller, and it has less computational burden....
DEFF Research Database (Denmark)
Blaabjerg, Frede; Aquila, A. Dell; Liserre, Marco
2004-01-01
of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters......A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study...
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Wang, Huai
2018-01-01
-Width Modulation (PWM) schemes. Both solutions will contribute to a degradation of the injected current quality. As a consequence, the harmonics induced by the dead time (referred to as "dead time harmonics" hereafter) have to be compensated in order to achieve a satisfactory current quality as required...... by standards. In this paper, the emission mechanism of dead time harmonics in single-phase PWM inverters is thus presented considering the modulation schemes in details. More importantly, a repetitive controller has been adopted to eliminate the dead time effect in single-phase grid-connected PWM converters....... The repetitive controller has been plugged into a proportional resonant-based fundamental current controller so as to mitigate the dead time harmonics and also maintain the control of the fundamental-frequency grid current in terms of dynamics. Simulations and experiments are provided, which confirm...
A Novel Single Phase Hybrid Switched Reluctance Motor Drive System
DEFF Research Database (Denmark)
Liang, Jianing; Xu, Guoqing; Jian, Linni
2011-01-01
phase boost converter is applied to improve the performance of this motor. It is easy to generate a double dclink voltage and dc-link voltage and switch both of them. The voltage of boost capacitor is self balance, so the protective circuit is not need to consider. The fast excitation mode helps hybrid......In this paper, a novel single phase hybrid switched reluctance motor(SRM) drive system is proposed. It integrated a single phase hybrid SRM and a novel single phase boost converter. This motor can reduce the number of phase switch. And the permanent magnet which is used in the motor can improve...... the performance and efficiency of SR motor. However, the inherent characteristic of this motor is that the negative torque is very sensitive with the excitation current near the turn-on angle. The slow excitation current limits the torque generation region and reduces the average torque. Therefore, a novel single...
DEFF Research Database (Denmark)
Kerekes, Tamas; Liserre, Marco; Mastromauro, R. A.
2009-01-01
Future ancillary services provided by photovoltaic (PV) systems could facilitate their penetration in power systems. Also low power PV systems can be designed to improve the power quality. This paper presents a single-phase photovoltaic system that provides grid voltage support and compensation...... of harmonic distortion at the point of common coupling (PCC) thanks to a repetitive controller. The power provided by the PV panels is controlled by a Maximum Power Point Tracking (MPPT) algorithm based on the incremental conductance method specifically modified to control the phase of the PV inverter voltage...
Ultrafast Switching Superjunction MOSFETs for Single Phase PFC Applications
DEFF Research Database (Denmark)
Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.
2014-01-01
This paper presents a guide on characterizing state-of-the-art silicon superjunction (SJ) devices in the 600V range for single phase power factor correction (PFC) applications. The characterization procedure is based on a minimally inductive double pulse tester (DPT) with a very low intrusive...... investigates the latest SJ devices in order to set a reference for future research on improvement over silicon (Si) attained with the introduction of wide bandgap devices in single phase PFC applications. The obtained results show that the latest generation of SJ devices set a new benchmark for its wide...
The Single-Phase ProtoDUNE Technical Design Report
Energy Technology Data Exchange (ETDEWEB)
Abi, B. [Univ. of Padova (Italy); et al.
2017-06-21
ProtoDUNE-SP is the single-phase DUNE Far Detector prototype that is under construction and will be operated at the CERN Neutrino Platform (NP) starting in 2018. ProtoDUNE-SP, a crucial part of the DUNE effort towards the construction of the first DUNE 10-kt fiducial mass far detector module (17 kt total LAr mass), is a significant experiment in its own right. With a total liquid argon (LAr) mass of 0.77 kt, it represents the largest monolithic single-phase LArTPC detector to be built to date. It's technical design is given in this report.
Directory of Open Access Journals (Sweden)
SANJEEV SINGH
2010-12-01
Full Text Available Permanent magnet brushless DC motor (PMBLDCM drives are being employed in many variable speed applications due to their high efficiency, silent operation, compact size, high reliability, ease of control, and low maintenance requirements. These drives have power quality problems and poor power factor at input AC mains as they are mostly fed through diode bridge rectifier based voltage source inverters. To overcome such problems a single-phase single-switch power factor correction AC-DC converter topology based on a Cuk converter is proposed to feed voltage source inverters based PMBLDCM. It focuses on the analysis, design and performance evaluation of the proposed PFC converter topology for a 1.5 kW, 1500 rpm, 400 V PMBLDCM drive used for an air-conditioning system. The proposed PFC converter topology is modelled and its performance is simulated in Matlab-Simulink environment and results show an improved power quality and good power factor in wide speed range of the drive.
the steady-state performance characteristics of single phase transfer
African Journals Online (AJOL)
2012-11-03
Nov 3, 2012 ... The paper reports the derivation of the steady- state equivalent circuit of a single phase transfer ... series opposition between the two halves of the ma- ..... from its equivalent circuit of fig 6 for different values of slip. Impedance due to forward field. Zf = Rf + jXf = Rr. 2(2s - 1). + jxr. 2. (19) in parallel with jxm. 2.
An Asymmetrical Space Vector Method for Single Phase Induction Motor
DEFF Research Database (Denmark)
Cui, Yuanhai; Blaabjerg, Frede; Andersen, Gert Karmisholt
2002-01-01
Single phase induction motors are the workhorses in low-power applications in the world, and also the variable speed is necessary. Normally it is achieved either by the mechanical method or by controlling the capacitor connected with the auxiliary winding. Any above method has some drawback which...
Improvement of Torque Production in Single-Phase Induction Motors ...
African Journals Online (AJOL)
Existing single phase induction motors exhibit low starting torque. Moreover, during accelerating time and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM ...
Load compensation for single phase system using series active filter ...
African Journals Online (AJOL)
In this paper a new control strategy for series active filter has been proposed for improvement of power quality problems in single phase system. Since the non linear loads in the system comprises of both voltage source harmonic and current source harmonic loads and the dominancy of each type of load varies from time to ...
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2013-01-01
The progressively growing of single-phase photovoltaic (PV) systems makes the Distribution System Operators (DSO) to update or revise the existing grid codes in order to guarantee the availability, quality and reliability of the electrical system. It is expected that the future PV systems connected...... to the low-voltage grid will be more active with functionalities of low voltage ride-through (LVRT) and the grid support capability, which is not the case today. In this paper, the operation principle is demonstrated for a single-phase grid-connected PV system in low voltage ride through operation in order...... to map future challenges. The system is verified by simulations and experiments. Test results show that the proposed power control method is effective and the single-phase PV inverters connected to low-voltage networks are ready to provide grid support and ride-through voltage fault capability...
INVERTER MULTI LEVEL TIPE JEMBATAN SATU FASA TIGA TINGKAT DENGAN MIKROKONTROLER AT89S51
Directory of Open Access Journals (Sweden)
A. Warsito A. Warsito
2012-02-01
Full Text Available Inverter is a power electronics circuit which is used to convert DC voltage and current to AC voltage andcurrent. In conventional inverter, most commonly used, only has three level voltage, those are +Vdc, -Vdc,and zero. Meanwhile both square inverters and SWPM inverter has big harmonic distortion. In SPWMinverter scheme, high frequency switching must be used to minimize total harmonic distortion (THD. Multilevel inverter is a type of inverter that has more than one level of voltage and current output.The major advantages of multi level inverters are a good voltage waveform, small harmonic dirtortion,switching component operated under low frequency, and it can supply a big power.This paper will discuse the construction of single phase three level multi level inverters, hardware testinginclude output waveform THD, and the comparisson of multilevel inverter with other conventional invertersscheme suc as PWM inverters modulation, and square waveform inverter. Atmel’s AT89S51 microcontrollerused to control switching scheme in this multi level inverter. By this power electronic circuit, it is expected alow cost and reliable multi level inverters prototipe.
Overview of Single-Phase Grid-Connected Photovoltaic Systems
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2017-01-01
A continuous booming installation of solar photovoltaic (PV) systems has been witnessed worldwide. It is mainly driven by the imperative demand of “clean” power generation from renewables. Grid-connected PV systems will thus become an even more active player in the future mixed power systems, which...... systems. This chapter thus gives an overview of the advancement of power electronics converters in single-phase grid-connected PV systems, being commonly used in residential applications. Demands to single-phase grid-connected PV systems and the general control strategies are also addressed...... are linked together by a vast of power electronics converters and the power grid. In order to achieve a reliable and efficient power generation from PV systems, more stringent demands have been imposed on the entire PV system. It, in return, advances the development of the power converter technology in PV...
Aalborg Inverter - A new type of “Buck in Buck, Boost in Boost” Grid-tied Inverter
DEFF Research Database (Denmark)
Wu, Weimin; Blaabjerg, Frede
2013-01-01
This paper presents a new family of high efficiency DC/AC grid-tied inverter with a wide variation of input DC voltage. It is a kind of “Boost in Boost, Buck in Buck” inverter, meaning that only one power stage works at the high frequency to achieve the minimum switching loss. Furthermore......, the minimum filtering inductance in the power loop is achieved to reduce the conduction power loss whether in “Boost” or “Buck” mode. In theory, it can achieve higher efficiency than other inverters under the same condition of input DC voltage. The principle of operation is fully illustrated through...... the analysis on the equivalent circuits of a “three-level” single-phase inverter. Simulations show it has good control performance....
Instantaneous power flow determination for single-phase UPFC
Energy Technology Data Exchange (ETDEWEB)
Dobrucky, B.; Drozdy, S.; Pokorny, M.; Pavlanin, R. [Zilina Univ., Zilina (Slovakia)
2007-07-01
The parallel shunt active filter in a unified power flow conditioner (UPFC) can filter and compensate the reactive power of basic and higher current harmonics. This paper reported on a study in which a new theory of orthogonal transform was used to control a single-phase UPFC system and transform it into a two-axes system. In addition to estimating the load current phase shifts, the study also determined the instantaneous active and reactive powers. The new theory is based on the premise that ordinary single-phase quantity can be complemented by a virtual fictitious phase so that both of them will create an orthogonal system, as is usual in three-phase systems. The theory uses efficient methods of analysis, such as time-sub-optimal determination of fundamental harmonics; average- and/or root-mean-square values; or instantaneous reactive power methods. The load current phase shift can be used to compensate for voltage drops. This paper outlined a practical application of the method in a case of active and reactive power determination for single-phase UPFC. It also presented some examples of the successful simulation experiments results focused on regulation output voltage of UPFC. 9 refs., 13 figs., 1 appendix.
Huang, Min; Blaabjerg, Frede; Yang, Yongheng; Wu, Weimin
2013-01-01
Traditionally, when designing an LCL-filter, a three-phase inverter is simplified as a single-phase inverter for analysis and the output phase voltage is used to calculate the inverter-side current harmonics and to design inverter-side inductor. However, for a three-phase three-wire grid-tied system, the output current harmonics of inverter are directly affected by the output line to line voltage. Hence, this paper proposes a new method to analyze the inverter output current harmonics by usin...
An Asymmetrical Space Vector Method for Single Phase Induction Motor
DEFF Research Database (Denmark)
Cui, Yuanhai; Blaabjerg, Frede; Andersen, Gert Karmisholt
2002-01-01
the motor torque performance is not good enough. This paper addresses a new control method, an asymmetrical space vector method with PWM modulation, also a three-phase inverter is used for the main winding and the auxiliary winding. This method with PWM modulation is implemented to control the motor speed...
Improvement of Torque Production in Single-Phase Induction Motors
African Journals Online (AJOL)
OLUWASOGO
and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM inverter to drive the existing motor is implemented in MATLAB/Simulink environment in this work.
A simple output voltage control scheme for single phase wavelet ...
African Journals Online (AJOL)
International Journal of Engineering, Science and Technology ... Wavelet based techniques have been extensively used in various power engineering applications. ... But, unlike other popular PWM schemes e.g. sinusoidal PWM, which offers independent control to both magnitude and frequency of fundamental inverter ...
Md Ruhul Amin; Shamsul Aizam Zulkifli
2017-01-01
In this paper, a fast self-synchronization known as virtual synchronous converter (VSCon) between single-phase microgrid and inverter in low-voltage microgrid, has been developed in Matlab/Simulink. The idea is to any phase locked loop (PLL) circuit for inverter-microgrid synchronization in order to improve the synchronization time. As known, it is difficult and lengthy process to tune the PLL gain parameters to reach suitable performance for synchronizing among the voltage, phase-angle and f...
Investigation of effect of single phase electrical faults at LOFT
International Nuclear Information System (INIS)
Yeates, J.A.
1978-01-01
This LTR presents the general basic engineering facts related to an open phase fault in a three phase power system commonly referred to as a single phase condition. It describes the probable results to electrical motors and describes the LOFT system design factors which minimize the likelihood of such a fault occurring at LOFT. It recognizes that the hazard of such a fault is a realistic threat and notes the types of relays designed to provide protection. Recommendations are made to perform a detailed engineering study to determine the most advantageous protective relay design, and to implement such a design by installation of the necessary devices and controls
Dynamics Assessment of Advanced Single-Phase PLL Structures
DEFF Research Database (Denmark)
Golestan, Saeed; Monfarad, Mohammad; Freijedo, Francisco D.
2013-01-01
, and desired performance under frequency-varying and harmonically distorted grid conditions. Despite the wide acceptance and use of these two advanced PLLs, no comprehensive design guidelines to fine-tune their parameters have been reported yet. Through a detailed mathematical analysis it is shown......Recently, several advanced phase locked loop (PLL) techniques have been proposed for single-phase applications. Among these, the Park-PLL, and the second order generalized integrator (SOGI) based PLL are very attractive, owing to their simple digital implementation, low computational burden...
Solution Concept of Modular Single Phase Active Power Filters
Directory of Open Access Journals (Sweden)
Marek Roch
2006-01-01
Full Text Available This paper investigates a modular or a decentralised single-phase active power filter control strategy. It is based on the evaluation of the harmonic reference load currents for the active power filter blocks operating under specific harmonic frequencies. The underlying principle of the modular active power filter is explained and it is shown how the required reference harmonic currents can be evaluated. Simulation results demonstrated the improvement in the dynamic performance of the modular active power filter presented here in comparison with the conventional type.
Synthesis and magnetic properties of single phase titanomagnetites
Energy Technology Data Exchange (ETDEWEB)
Schoenthal, W., E-mail: wms@andrew.cmu.edu; Liu, X.; Cox, T.; Laughlin, D. E.; McHenry, M. E. [Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Mesa, J. L.; Diaz-Michelena, M. [Instituto Nacional de Tecnica Aeroespacial, Madrid (Spain); Maicas, M. [Universidad Politecnica de Madrid, ISOM-ETSIT, Madrid (Spain)
2014-05-07
The focus of this paper is the study of cation distributions and resulting magnetizations in titanomagnetites (TMs), (1−x)Fe{sub 3}O{sub 4−x}Fe{sub 2}TiO{sub 4} solid solutions. TM remnant states are hypothesized to contribute to planetary magnetic field anomalies. This work correlates experimental data with proposed models for the TM pseudobinary. Improved synthesis procedures are reported for single phase Ulvöspinel (Fe{sub 2}TiO{sub 4}), and TM solid solutions were made using solid state synthesis techniques. X-ray diffraction and scanning electron microscopy show samples to be single phase solid solutions. M-H curves of TM75, 80, 85, 90, and 95 (TMX where X = at. % of ulvöspinel) were measured using a Physical Property Measurement System at 10 K, in fields of 0 to 8 T. The saturation magnetization was found to be close to that predicted by the Neel model for cation distribution in TMs. M-T curves of the remnant magnetization were measured from 10 K to 350 K. The remnant magnetization was acquired at 10 K by applying an 8 T field and then releasing the field. Experimental Neel temperatures are reported for samples in the Neel model ground state.
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede; Borup, Uffe
2004-01-01
The PI current control of a single-phase inverter has well known drawbacks: steady-state magnitude and phase-error and limited disturbance rejection capability. When the current controlled inverter is connected to the grid, the phase error results in a power factor decrement and the limited distu...
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede; Borup, Uffe
2004-01-01
The PI current control of a single-phase inverter has well known drawbacks: steady-state magnitude and phase-error and limited disturbance rejection capability. When the current controlled inverter is connected to the grid, the phase error results in a power factor decrement and the limited...
A Hybrid Power Control Concept for PV Inverters with Reduced Thermal Loading
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
on a single-phase PV inverter under yearly operation is presented with analyses of the thermal loading, lifetime, and annual energy yield. It has revealed the trade-off factors to select the power limit and also verified the feasibility and the effectiveness of the proposed control concept....
Passive P-control of a grid-connected photovoltaic inverter
Meza, C.; Jeltsema, D.; Scherpen, J. M. A.; Biel, D.
2008-01-01
A passive P-controller for a single-phase single-stage grid-connected photovoltaic inverter is presented. Explicit dependance of the PV array parameters on external unpredictable variables such as temperature and solar irradiance is avoided by extending the control scheme with a reference estimator.
Energy Technology Data Exchange (ETDEWEB)
Zhao, Zilai [General Motors LLC, Detroit, MI (United States); Gough, Charles [General Motors LLC, Detroit, MI (United States)
2016-04-22
The goal of this Cooperative Agreement was the development of a Next Generation Inverter for General Motors’ electrified vehicles, including battery electric vehicles, range extended electric vehicles, plug-in hybrid electric vehicles and hybrid electric vehicles. The inverter is a critical electronics component that converts battery power (DC) to and from the electric power for the motor (AC).
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang
2014-01-01
This paper introduces a new 3-phase Y-source inverter whose gain is presently not matched by classical impedance-network-based inverters operating at the same duty ratio. The proposed network uses a tightly coupled transformer with three windings. By squeezing the shoot-through range while keeping...
Ma, Mingyao; Hu, Haibing; Kutkut, Nasser; Batarseh, Issa; Shen, John; , Bkayrat, Raed
2017-08-01
A system connected to an AC power grid having an AC phase signal includes an inverter module including a first inverter coupled to a DC voltage, actuated based on the AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. A second inverter includes second switch elements coupled to the DC voltage and actuated by a second set of control signals phase delayed with respect to the first control signals. A transformer module has first and second primary windings coupled to the first and second inverters. The transformer module further includes a secondary winding coupled to first primary winding, the second primary winding, and the AC power grid. The secondary winding is configured to provide a secondary output voltage to the AC power grid by combining the first voltage signal and the second voltage signal such that the predetermined harmonic components are substantially cancelled.
Model Based Control of Single-Phase Marine Cooling Systems
DEFF Research Database (Denmark)
Hansen, Michael
2014-01-01
these systems. Traditionally, control for this type of cooling system has been limited to open-loop control of pumps combined with a couple of local PID controllers for bypass valves to keep critical temperatures within design limits. This research considers improvements in a retrofit framework to the control...... linearization, an H∞-control design is applied to the resulting linear system. Disturbance rejection capabilities and robustness of performance for this control design methodology is compared to a baseline design derived from classical control theory. This shows promising results for the nonlinear robust design......This thesis is concerned with the problem of designing model-based control for a class of single-phase marine cooling systems. While this type of cooling system has been in existence for several decades, it is only recently that energy efficiency has become a focus point in the design and operation...
Benchmarks for single-phase flow in fractured porous media
Flemisch, Bernd; Berre, Inga; Boon, Wietse; Fumagalli, Alessio; Schwenck, Nicolas; Scotti, Anna; Stefansson, Ivar; Tatomir, Alexandru
2018-01-01
This paper presents several test cases intended to be benchmarks for numerical schemes for single-phase fluid flow in fractured porous media. A number of solution strategies are compared, including a vertex and two cell-centred finite volume methods, a non-conforming embedded discrete fracture model, a primal and a dual extended finite element formulation, and a mortar discrete fracture model. The proposed benchmarks test the schemes by increasing the difficulties in terms of network geometry, e.g. intersecting fractures, and physical parameters, e.g. low and high fracture-matrix permeability ratio as well as heterogeneous fracture permeabilities. For each problem, the results presented are the number of unknowns, the approximation errors in the porous matrix and in the fractures with respect to a reference solution, and the sparsity and condition number of the discretized linear system. All data and meshes used in this study are publicly available for further comparisons.
Indirect control of a single-phase active power filter
Directory of Open Access Journals (Sweden)
Mihai CULEA
2006-12-01
Full Text Available The control of shunt active power filters using PWM inverters consists in generating a reference by separating, using different methods, the harmonics to be eliminated. The methods used are time-consuming and need dedicated control and signal processing equipments. To avoid these setbacks a new method is proposed in the paper. The active power filter is a current PWM rectifier with voltage output and with a capacitor on the DC side. The PWM rectifier is controlled so that the sum of its current and the load’s current is a sinusoid. The control block as well as simulation results are presented.
Modeling And Simulation Of Highly Advanced Multilevel Inverter For Speed Control Of Induction Motor
Directory of Open Access Journals (Sweden)
Ravi Raj
2017-02-01
Full Text Available In this Paper the problem of removing Power dissipation from single phase Induction Motor with DC sources is considered by the speed control of Induction Motor with highly advanced 9-Level multi-level Inverter which having approximate zero Harmonics. As the demand of power is increasing day by day. So that we must introduced very advanced Electrical Instruments which having high efficiency and less dissipation of power. The requirement of very advanced Inverter is necessary. Here we are designing a Multi-level Inverter up to the 9-level using IGBT Insulated-gate bipolar transistor by Mat lab which having negligible total harmonic distortion THD thats why it will control the speed of single phase Induction motor which is presently widely used in our daily needs. Also several informative Simulation results verify the authority and truthiness of the proposed Model.
Directory of Open Access Journals (Sweden)
Abdal Karim Z. Mansoor
2013-05-01
Full Text Available This paper presents design and analysis of a single phase multilevel inverter by optimizing both switching angles and DC link voltage of a cascaded inverter. The switching angles and dc link voltage are chosen such that to minimize the total harmonic distortion of the output voltage. The main power devices are switched only once per cycle , so that to overcome the switching loss problem, as well as electromagnetic interference (EMI problem, a method is given to determine the optimum value of the switching angles and the value of the dc link voltage. Theoretical analysis and simulation of a single phase 5-level cascaded inverter are introduced with a wide range of modulation index
A New LCL -Filter With In-Series Parallel Resonant Circuit for Single-Phase Grid-Tied Inverter
DEFF Research Database (Denmark)
Wu, Weimin; Sun, Yunjie; Lin, Zhe
2014-01-01
are investigated for the conventional LCL-filter-based system. Based on this, a modified LCL-filter topology using an extra parallel LrCr resonant circuit is proposed to reduce the total inductance value, without increasing the capacitive reactive power. The validity is verified through the experiments on a 500-W...
DEFF Research Database (Denmark)
Guo, Xiaoqiang; Guerrero, Josep M.
2016-01-01
done indicates that the widely used PR (P+Resonant) control is just a special case of the proposed control solution. The time-domain simulation in Matlab/Simulink and experimental results from a TMS320F2812 DSP based laboratory prototypes are in good agreement, which verify the effectiveness...
DEFF Research Database (Denmark)
Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil
2018-01-01
New interconnection standards for Photovoltaic systems are going to be mandatory in some countries. Such that the next generation of PV should support a full range of operation mode like in a power plant and also support Low-Voltage Ride-Through (LVRT) capability during voltage sag fault. Since......, these methods have had uncertainties in respect their contribution in LVRT mode. In PR controllers, a fast dynamic response can be obtained by tuning the gains of PR controllers for a high bandwidth, but typically the phase margin is decreased. Therefore, the design of PR controllers needs a tradeoff between...
DEFF Research Database (Denmark)
Ko, Youngjong; Park, Kiwoo; Lee, Kyo-Beum
2011-01-01
In a grid connected power conversion system, the phase angle information of a grid voltage is very essential for supplying power to the grid since it is used for active and reactive power control. A Phase Locked Loop (PLL) system is used and should be robust because often the actual grid voltages...... into fundamental and harmonic components and a virtual phase voltage is generated from the fundamental component using a Full Order Observer (FOO). Two virtual voltages are used as an input for the PLL system so the phase angle errors can be reduced and the output power quality can be improved. The dynamic...... are usually distorted by unexpected harmonics. However, conventional PLL systems have steady state errors when distorted voltages are used as a PLL input. Furthermore, using this distorted phase angle in the power control could reduce the output power quality. In this paper, the grid voltages are separated...
Su, Gui-Jia
2003-06-10
A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.
Nagano, S.
1979-01-01
Base driver with common-load-current feedback protects paralleled inverter systems from open or short circuits. Circuit eliminates total system oscillation that can occur in conventional inverters because of open circuit in primary transformer winding. Common feedback signal produced by functioning modules forces operating frequency of failed module to coincide with clock drive so module resumes normal operating frequency in spite of open circuit.
Self-assembled single-phase perovskite nanocomposite thin films.
Kim, Hyun-Suk; Bi, Lei; Paik, Hanjong; Yang, Dae-Jin; Park, Yun Chang; Dionne, Gerald F; Ross, Caroline A
2010-02-10
Thin films of perovskite-structured oxides with general formula ABO(3) have great potential in electronic devices because of their unique properties, which include the high dielectric constant of titanates, (1) high-T(C) superconductivity in cuprates, (2) and colossal magnetoresistance in manganites. (3) These properties are intimately dependent on, and can therefore be tailored by, the microstructure, orientation, and strain state of the film. Here, we demonstrate the growth of cubic Sr(Ti,Fe)O(3) (STF) films with an unusual self-assembled nanocomposite microstructure consisting of (100) and (110)-oriented crystals, both of which grow epitaxially with respect to the Si substrate and which are therefore homoepitaxial with each other. These structures differ from previously reported self-assembled oxide nanocomposites, which consist either of two different materials (4-7) or of single-phase distorted-cubic materials that exhibit two or more variants. (8-12) Moreover, an epitaxial nanocomposite SrTiO(3) overlayer can be grown on the STF, extending the range of compositions over which this microstructure can be formed. This offers the potential for the implementation of self-organized optical/ferromagnetic or ferromagnetic/ferroelectric hybrid nanostructures integrated on technologically important Si substrates with applications in magnetooptical or spintronic devices.
Power decoupling method for single phase differential buck converter
DEFF Research Database (Denmark)
Yao, Wenli; Tang, Yi; Zhang, Xiaobin
2015-01-01
inverter to improve the dc link power quality, and an improved active power decoupling method is proposed to achieve ripple power reduction for both AC-DC and DC-AC conversions. The ripple energy storage is realized by the filter capacitors, which are connected between the output terminal and the negative...... generation technique is proposed to provide accurate ripple power compensation, and closed-loop controllers are also designed based on small signal models. The effectiveness of this power decoupling method is verified by detailed simulation studies as well as laboratory prototype experimental results....... dc bus. By properly controlling the differential mode voltage of the capacitors, it is possible to transfer desired energy between the DC port and AC port. The common mode voltage is controlled in such a way that the ripple power on the dc side will be reduced. Furthermore, an autonomous reference...
DEFF Research Database (Denmark)
Liu, Xiong; Wang, Peng; Loh, Poh Chiang
2011-01-01
This paper proposes an approach for DC-link second-order harmonic power cancellation in single-phase AC/DC/AC converter with reduced number of switches. The proposed six-switch converter has two bridges with three switches in each of them, where the middle switch in each bridge is shared by the AC....../DC rectifier and DC/AC inverter. A small size DC-link capacitor can be achieved through coordination control of rectifier and inverter to cancel the second-order oscillation power. Maximum available phase difference between rectifier’s and inverter’s modulation references is investigated to be dependent...... on their modulation indices of the six-switch converter, and high modulation indices are proved to be feasible for second-order power cancellation in the DC-link based on the phase difference analysis. Both reduced switch numbers and DC electrolytic capacitor size can be achieved using the proposed converter...
Energy Technology Data Exchange (ETDEWEB)
Hoke, Anderson [National Renewable Energy Lab. (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Miller, Brian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bell, Frances [SolarCity, San Mateo, CA (United States); McCarty, Michael [SolarCity, San Mateo, CA (United States)
2016-07-01
As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1.) In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2.) The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness. Crucially, the multi-inverter anti-islanding tests described in this report examine scenarios with multiple inverters connected to multiple different points on the grid. While this so-called 'solar subdivision' scenario has been examined to some extent through simulation, this is the first known work to test it using hardware inverters. This was accomplished through the use of power hardware-in-the-loop (PHIL) simulation, which allows the hardware inverters to be connected to a real-time transient simulation of an electric power system that can be easily reconfigured to test various distribution circuit scenarios. The anti-islanding test design was a modified version of the unintentional islanding test in IEEE Standard 1547.1, which creates a balanced, resonant island with the intent of creating a highly challenging condition for island detection. Three common, commercially available single-phase PV inverters from three different manufacturers were tested. The first part of this work examined each inverter individually using a series of pure hardware resistive-inductive-capacitive (RLC
Analysis and Design of Solar Photo voltaic Grid Connected Inverter
Directory of Open Access Journals (Sweden)
Muddasani Satyanarayana
2015-08-01
Full Text Available This paper presents common mode voltage analysis of single phase grid connected photovoltaic inverter. Many researchers proposed different grid tie inverters for applications like domestic powering, street lighting, water pumping, cooling and heating applications, however traditional grid tie PV inverter uses either a line frequency or a high frequency transformer between the inverter and grid but losses will increase in the network leading to reduced efficiency of the system. In order to increase the efficiency, with reduced size and cost of the system, the effective solution is to remove the isolation transformer. But common mode (CM ground leakage current due to parasitic capacitance between the PV panels and the ground making the system unreliable. The common mode current reduces the efficiency of power conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give rise to the safety threats. In order to eliminate the common mode leakage current in Transformerless PV systm two control algorithms of multi-carrier pwm are implemented and compared for performance analysis.The shoot-through issue that is encountered by traditional voltage source inverter is analyzed for enhanced system reliability. These control algorithms are compared for common mode voltage and THD comparisons. The proposed system is designed using MATLAB/SIMULINK software for analysis.
Energy Technology Data Exchange (ETDEWEB)
Landau, M.; Engler, A.; Geipel, R.; Strauss, P. [Institut fuer Solare Energieversorgungstechnik (ISET), Kassel (Germany); Heinzemann, T.; Rothert, M. [SMA System-, Mess- und Anlagentechnik - Regelsysteme GmbH, Niestetal (Germany)
2004-07-01
In the bay of Gaidouromandra on the Greek island of Kythnos two three phase power supply systems were set up and operated within the frame of two European projects from 2000 to 2001. One is a PV-battery system and the other one is a PV-battery-diesel system. A speciality of both systems is the distributed PV-generation with the solar panels and PV-inverters (Sunny Boy {sup registered}) installed on the properties of several inhabitants. With the combination of both supply systems and changing the grid topology from three to single phase operation the problems further developments and a lot of system advantages could be demonstrated. The implementation of the new SELFSYNC {sup registered} multi master control method resulted in further improvement concerning available peak power and system reliability. In June 2003 the two three phase supply systems were converted into one single phase system. First operation experience is available and reported on. It is shown, that a suitable grid topology and interconnection result in advantages for the overall supply system. The benefits of the parallel operation of three Sunny Island {sup registered} battery inverters on a single phase are: (1) less inverters necessary, (2) lower idle consumption of the overall system, (3) increased power of the single phase and (4) redundancy. (orig.)
Five-level inverter with dual reference modulation technique for grid-connected PV system
Energy Technology Data Exchange (ETDEWEB)
Rahim, N.A.; Selvaraj, J.; Krismadinata, C. [Centre for Power Electronics, Drives, Automation and Control, Department of Electrical Engineering, University of Malaya, Jalan Pantai Bahru, 50603 Kuala Lumpur (Malaysia)
2010-03-15
This paper presents a single-phase five-level grid-connected PV inverter with a novel dual reference modulation technique. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate PWM signals. The inverter consists of a full-bridge inverter and an auxiliary circuit comprising four diodes and a switch. The inverter produces output voltage in five levels: zero, +1/2V{sub dc}, V{sub dc}, -1/2V{sub dc} and -V{sub dc}. A digital PI current control algorithm is implemented in DSP TMS320F2812 to keep the current injected into the grid sinusoidal and to have high dynamic performance with low THD. The validity of the proposed inverter is verified through simulation and implemented in a prototype. The experimental results are compared with conventional single-phase three-level grid-connected PWM inverter in terms of THD. (author)
Servo characteristics of single-phase spindle motor in DVD-ROM
Wang, KingYin; Kuei, ChingPing; Chang, SungSan; Lee, YaoYu; Kuo, YuHung
2000-07-01
The single-phase DC motor has the low-cost advantage over 3- phase DC motor owing to its easy-assembling and high yield- rate, however, it has larger torque ripple and cogging torque. Single-phase DC motor is currently applied to low profit margin products such as cooling fan. In order to utilize single-phase DC motor to high precision system, for instance, DVD (Digital Versatile Disk), the vibration caused by torque ripple and cogging torque needs to be solved. In this paper, focusing error, tracking error, seeking ability and some velocity control performances are studied when single-phase DC motor is used in DVD related products.
Equivalence of two models in single-phase multicomponent flow simulations
Wu, Yuanqing
2016-02-28
In this work, two models to simulate the single-phase multicomponent flow in reservoirs are introduced: single-phase multicomponent flow model and two-phase compositional flow model. Because the single-phase multicomponent flow is a special case of the two-phase compositional flow, the two-phase compositional flow model can also simulate the case. We compare and analyze the two models when simulating the single-phase multicomponent flow, and then demonstrate the equivalence of the two models mathematically. An experiment is also carried out to verify the equivalence of the two models.
Lai, J.S.; Young, R.W. Sr.; Chen, D.; Scudiere, M.B.; Ott, G.W. Jr.; White, C.P.; McKeever, J.W.
1997-06-24
A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 14 figs.
Lai, Jih-Sheng; Young, Sr., Robert W.; Chen, Daoshen; Scudiere, Matthew B.; Ott, Jr., George W.; White, Clifford P.; McKeever, John W.
1997-01-01
A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.
International Nuclear Information System (INIS)
P.S. Domski
2000-01-01
As directed by a written development plan (CRWMS M andO 1999a), a conceptual model for water entering the drift and reacting with the invert materials is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction, and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE), Revision 2 (NRC 1999). This AMR also seeks to: (1) Develop a logical conceptual model for physical/chemical interactions between seepage and the invert materials; (2) screen potential processes and reactions that may occur between seepage and invert to evaluate the potential consequences of the interactions; and (3) outline how seepage/invert processes may be quantified. This document provides the conceptual framework for screening out insignificant processes and for identifying and evaluating those seepage/invert interactions that have the potential to be important to subsequent PAO analyses including the Engineered Barrier System (EBS) physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. Additionally, the concepts discussed within this report may also apply to certain near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts. The seepage/invert interactions will not directly affect any principal factors
Power Loss Analysis and Comparision of DC and AC Side Decoupling Module in a H-bridge Inverter
DEFF Research Database (Denmark)
Ma, Siyuan; Wang, Haoran; Zhu, Guorong
2016-01-01
perspective. The analytical power loss models are derived based on the operation principles of the active power decoupling methods. A comparative study is performed based on a 500 W single-phase H-bridge inverter study case with 400 V DC-link voltage level. The results provide a guideline to justify whether...
Structure and magnetism of single-phase epitaxial gamma '-Fe4N
Costa-Kramer, JL; Borsa, DM; Garcia-Martin, JM; Martin-Gonzalez, MS; Boerma, DO; Briones, F
Single phase epitaxial pure gamma(')-Fe4N films are grown on MgO (001) by molecular beam epitaxy of iron in the presence of nitrogen obtained from a radio frequency atomic source. The epitaxial, single phase nature of the films is revealed by x-ray diffraction and by the local magnetic environment
Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines
DEFF Research Database (Denmark)
Lu, Kaiyuan; Ritchie, Ewen
2011-01-01
The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....
Rippel, W. E.; Edwards, D. B.
1984-01-01
Commutation by field-effect transistor allows more efficient operation. High voltage field-effect transistor (FET) controls silicon controlled rectifiers (SCR's). Circuit requires only one capacitor and one inductor in commutation circuit: simpler, more efficient, and more economical than conventional inverters. Adaptable to dc-to-dc converters.
Inverter communications using output signal
Chapman, Patrick L.
2017-02-07
Technologies for communicating information from an inverter configured for the conversion of direct current (DC) power generated from an alternative source to alternating current (AC) power are disclosed. The technologies include determining information to be transmitted from the inverter over a power line cable connected to the inverter and controlling the operation of an output converter of the inverter as a function of the information to be transmitted to cause the output converter to generate an output waveform having the information modulated thereon.
Inverting the Linear Algebra Classroom
Talbert, Robert
2014-01-01
The inverted classroom is a course design model in which students' initial contact with new information takes place outside of class meetings, and students spend class time on high-level sense-making activities. The inverted classroom model is so called because it inverts or "flips" the usual classroom design where typically class…
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
This paper introduces a new inverter topology called a “quasi-Y-source inverter”. The proposed inverter inherits all the advantages of the original Y-source inverter. In addition, the new topology draws continuous current from the source which is required for many renewable sources. It also has dc...
Mclyman, C. W.
1983-01-01
Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.
A New Green Power Inverter for Fuel Cells
DEFF Research Database (Denmark)
Andersen, Gert Karmisholt; Klumpner, Christian; Kjær, Søren Bækhøj
2002-01-01
startup. The inverter is controlled as a power factor controller with resistor emulation.Experimental results of converter efficiency, grid performance and fuel cell response are shown for a 1 kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92......This paper presents a new grid connected inverter for fuel cells. It consists of a two stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25 V-45 V) this volt- age must be transformed to around 350-400 V in order to invert this dc power into ac...... power to the grid. The proposed converter consists of an isolated dc-dc converter cascaded with a single phase H-bridge inverter. The dc-dc converter is a current-fed push-pull converter. A new dedicated voltage mode startup procedure has been developed in order to limit the inrush current during...
Inverter ratio failure detector
Wagner, A. P.; Ebersole, T. J.; Andrews, R. E. (Inventor)
1974-01-01
A failure detector which detects the failure of a dc to ac inverter is disclosed. The inverter under failureless conditions is characterized by a known linear relationship of its input and output voltages and by a known linear relationship of its input and output currents. The detector includes circuitry which is responsive to the detector's input and output voltages and which provides a failure-indicating signal only when the monitored output voltage is less by a selected factor, than the expected output voltage for the monitored input voltage, based on the known voltages' relationship. Similarly, the detector includes circuitry which is responsive to the input and output currents and provides a failure-indicating signal only when the input current exceeds by a selected factor the expected input current for the monitored output current based on the known currents' relationship.
Grid-Connected Control Strategy of Five-level Inverter Based on Passive E-L Model
Directory of Open Access Journals (Sweden)
Tao Li
2017-10-01
Full Text Available At present, the research on five-level inverters mainly involves the modulation algorithm and topology, and few articles study the five-level inverter from the control strategy. In this paper, the nonlinear passivity-based control (PBC method is proposed for single-phase uninterruptible power supply inverters. The proposed PBC method is based on an energy shaping and damping injection idea, which is performed to regulate the energy flow of an inverter to a desired level and to assure global asymptotic stability, respectively. Furthermore, this paper presents a control algorithm based on the theory of passivity that gives an inverter in a photovoltaic system additional functions: power factor correction, harmonic currents compensation, and the ability to stabilize the system under varying injection damping. Finally, the effectiveness of the PBC method in terms of both stability and harmonic distortion is verified by the simulation and experiments under resistive and inductive loads.
Directory of Open Access Journals (Sweden)
Abdelmajid Abouloifa
2018-01-01
Full Text Available This paper addresses the problem of controlling the single-phase grid connected to the photovoltaic system through a full bridge inverter with LCL-filter. The control aims are threefold: (i imposing the voltage in the output of PV panel to track a reference provided by the MPPT block; (ii regulating the DC-link voltage to guarantee the power exchange between the source and AC grid; (iii ensuring a satisfactory power factor correction (PFC. The problem is dealt with using a cascade nonlinear adaptive controller that is developed making use of sliding-mode technique and observers in order to estimate the state variables and grid parameters, by measuring only the grid current, PV voltage, and the DC bus voltage. The control problem addressed by this work involves several difficulties, including the uncertainty of some parameters of the system and the numerous state variables are inaccessible to measurements. The results are confirmed by simulation under MATLAB∖Simulink∖SimPowerSystems, which show that the proposed regulator is robust with respect to climate changes.
Light-Weight, Low-Cost, Single-Phase, Liquid-Cooled Cold Plate (Presentation)
Energy Technology Data Exchange (ETDEWEB)
Narumanchi, S.
2013-07-01
This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.
American Society for Testing and Materials. Philadelphia
1983-01-01
1.1 This specification covers the basic requirements for equipment to be used for the collection of uncontaminated and representative samples from single-phase geothermal liquid or steam. Geopressured liquids are included. See Fig 1.
DEFF Research Database (Denmark)
Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede
2010-01-01
Z-source inverters are recent topological options proposed for buck–boost energy conversion with a number of possible voltage- and current-type circuitries already reported in the literature. Comparing them, a common feature noted is their inclusion of an LC impedance network, placed between the dc...... input source and inverter bridge. This impedance network allows the output end of a voltage-type Z-source inverter to be shorted for voltage boosting without causing a large current flow and the terminal current of a current-type inverter to be interrupted for current boosting without introducing...... overvoltage oscillations to the system. Therefore, Z-source inverters are, in effect, safer and less complex and can be implemented using only passive elements with no additional active semiconductor needed. Believing in the prospects of Z-source inverters, this paper contributes by introducing a new family...
DEFF Research Database (Denmark)
Blaabjerg, Frede; Loh, Poh Chiang; Gao, F.
2008-01-01
Z-source inverters are recent topological options proposed for buck-boost energy conversion with a number of possible voltage and current-type circuitries already reported in the literature. Comparing them, a common feature noted is their inclusion of a LC impedance network, placed between the dc...... input source and inverter bridge. This impedance network allows the output end of a voltage-type Z-source inverter to be shorted for voltage-boosting without causing a large current flow, and the terminal current of a current-type inverter to be interrupted for current boosting without introducing over......-voltage oscillations to the system. Therefore, Z-source inverters are in effect safer and less complex, and can be implemented using only passive elements with no additional active semiconductor needed. Believing in the prospects of Z-source inverters, this paper contributes by introducing a new family of embedded EZ-source...
DEFF Research Database (Denmark)
Anthon, Alexander
and preferably low complexity leads to new research demands. This is especially true in the field of low cost residential PV inverters where efficiencies are used as major selling arguments. Traditional converter topologies equipped with conventional Silicon based semiconductors to date reach their limitations......, a replacement of only two switching devices per phase leg can greatly reduce the semiconductor losses. The Hybrid-NPC converter can be seen as an attractive and cost competitive alternative to the Silicon Carbide based converter, also allowing to overcome the major drawbacks with the conventional Silicon IGBT...
Gas cooled traction drive inverter
Chinthavali, Madhu Sudhan
2013-10-08
The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.
DEFF Research Database (Denmark)
Loh, Poh Chiang; Li, Ding; Blaabjerg, Frede
2013-01-01
Voltage-type Γ-Z-source inverters are proposed in this letter. They use a unique Γ-shaped impedance network for boosting their output voltage in addition to their usual voltage-buck behavior. Comparing them with other topologies, the proposed inverters use lesser components and a coupled transfor......Voltage-type Γ-Z-source inverters are proposed in this letter. They use a unique Γ-shaped impedance network for boosting their output voltage in addition to their usual voltage-buck behavior. Comparing them with other topologies, the proposed inverters use lesser components and a coupled...
Cavanna, F; Touramanis, C
2017-01-01
ProtoDUNE-SP is the single-phase DUNE Far Detector prototype that is under construction and will be operated at the CERN Neutrino Platform (NP) starting in 2018. It was proposed to the CERN SPSC in June 2015 (SPSC-P-351) and was approved in December 2015 as experiment NP04 (ProtoDUNE). ProtoDUNE-SP, a crucial part of the DUNE effort towards the construction of the first DUNE 10-kt fiducial mass far detector module (17 kt total LAr mass), is a significant experiment in its own right. With a total liquid argon (LAr) mass of 0.77 kt, it represents the largest monolithic single phase LArTPC detector to be built to date. It is housed in an extension to the EHN1 hall in the North Area, where the CERN NP is providing a new dedicated charged-particle test beamline. ProtoDUNE-SP aims to take its first beam data before the LHC long shutdown (LS2) at the end of 2018. ProtoDUNE-SP prototypes the designs of most of the single-phase DUNE far detector module (DUNE-SP) components at a 1:1 scale, with an extrapolation of abo...
Single-Phase DC-AC Boost Converter | Odeh | Nigerian Journal of ...
African Journals Online (AJOL)
The proposed boost inverter configuration performs single stage power conversion, which minimizes switching losses and attains higher efficiency as compared to the conventional boost inverter. The steady-state operating principle of the power circuit configuration and control strategy are described. A multi-loop structure ...
Searching for Next Single-Phase High-Entropy Alloy Compositions
Directory of Open Access Journals (Sweden)
David E. Alman
2013-10-01
Full Text Available There has been considerable technological interest in high-entropy alloys (HEAs since the initial publications on the topic appeared in 2004. However, only several of the alloys investigated are truly single-phase solid solution compositions. These include the FCC alloys CoCrFeNi and CoCrFeMnNi based on 3d transition metals elements and BCC alloys NbMoTaW, NbMoTaVW, and HfNbTaTiZr based on refractory metals. The search for new single-phase HEAs compositions has been hindered by a lack of an effective scientific strategy for alloy design. This report shows that the chemical interactions and atomic diffusivities predicted from ab initio molecular dynamics simulations which are closely related to primary crystallization during solidification can be used to assist in identifying single phase high-entropy solid solution compositions. Further, combining these simulations with phase diagram calculations via the CALPHAD method and inspection of existing phase diagrams is an effective strategy to accelerate the discovery of new single-phase HEAs. This methodology was used to predict new single-phase HEA compositions. These are FCC alloys comprised of CoFeMnNi, CuNiPdPt and CuNiPdPtRh, and HCP alloys of CoOsReRu.
Simplified High-Power Inverter
Edwards, D. B.; Rippel, W. E.
1984-01-01
Solid-state inverter simplified by use of single gate-turnoff device (GTO) to commutate multiple silicon controlled rectifiers (SCR's). By eliminating conventional commutation circuitry, GTO reduces cost, size and weight. GTO commutation applicable to inverters of greater than 1-kilowatt capacity. Applications include emergency power, load leveling, drives for traction and stationary polyphase motors, and photovoltaic-power conditioning.
Analysis of Multicarrier PWM techniques for Photovoltaic fed Cascaded H-Bridge Multilevel Inverter
Directory of Open Access Journals (Sweden)
VENKATRAMAN Thiyagarajan
2017-05-01
Full Text Available Recently multilevel inverter technology emerging as an important alternative in the field of high power, medium voltage energy control. The various topologies for multilevel inverters such as diode-clamped, flying capacitor and cascaded H-bridge have been proposed over the years. This paper analysis the performance of a single phase seven level cascaded H-bridge inverter for photovoltaic applications. The Phase Disposition PWM (PDPWM technique is used to generate gate signals. The performance is compared for both sinusoidal reference waveform and trapezoidal reference waveform. The analysis is carried out for different modulation index and different shading pattern of photovoltaic (PV array. The simulation is carried out using MATLAB/SIMULINK software.
Directory of Open Access Journals (Sweden)
J. Fallah Ardashir
2017-06-01
Full Text Available This paper proposes a new single phase transformerless Photovoltaic (PV inverter for grid connected systems. It consists of six power switches, two diodes, one capacitor and filter at the output stage. The neutral of the grid is directly connected to the negative terminal of the source. This results in constant common mode voltage and zero leakage current. Model Predictive Controller (MPC technique is used to modulate the converter to reduce the output current ripple and filter requirements. The main advantages of this inverter are compact size, low cost, flexible grounding configuration. Due to brevity, the operating principle and analysis of the proposed circuit are presented in brief. Simulation and experimental results of 200W prototype are shown at the end to validate the proposed topology and concept. The results obtained clearly verifies the performance of the proposed inverter and its practical application for grid connected PV systems.
Directory of Open Access Journals (Sweden)
MUDASIR AHMED MEMON
2017-01-01
Full Text Available In this paper, PSO (Particle Swarm Optimization based technique is proposed to derive optimized switching angles that minimizes the THD (Total Harmonic Distortion and reduces the effect of selected low order non-triple harmonics from the output of the multilevel inverter. Conventional harmonic elimination techniques have plenty of limitations, and other heuristic techniques also not provide the satisfactory results. In this paper, single phase symmetrical cascaded H-Bridge 11-Level multilevel inverter is considered, and proposed algorithm is utilized to obtain the optimized switching angles that reduced the effect of 5th, 7th, 11th and 13th non-triplen harmonics from the output voltage of the multilevel inverter. A simulation result indicates that this technique outperforms other methods in terms of minimizing THD and provides high-quality output voltage waveform.
Experimental Evaluation of Grid Support Enabled PV Inverter Response to Abnormal Grid Conditions
Energy Technology Data Exchange (ETDEWEB)
Nelson, Austin A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Martin, Gregory D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hurtt, James [Florida Power and Light Company
2017-10-03
As revised interconnection standards for grid-tied photovoltaic (PV) inverters address new advanced grid support functions (GSFs), there is increasing interest in inverter performance in the case of abnormal grid conditions. The growth of GSF-enabled inverters has outpaced the industry standards that define their operation, although recently published updates to UL1741 Supplement SA define test conditions for GSFs such as volt-var control, frequency-watt control, and voltage/frequency ride-through, among others. This paper describes the results of a comparative experimental evaluation on four commercially available, three-phase PV inverters in the 24.0-39.8 kVA power range on their GSF capability and its effect on abnormal grid condition response. The evaluation examined the impact particular GSF implementations have on run-on times during islanding conditions, peak voltages in load rejection overvoltage scenarios, and peak currents during single-phase and three-phase fault events for individual inverters. Testing results indicated a wide variance in the performance of GSF enabled inverters to various test cases.
A Comparison between Buck-Boost Inverter with and without Buffer Inductor
Directory of Open Access Journals (Sweden)
Purwadi Agus Darwito
2012-05-01
Full Text Available The electric vehicle inverter requires an induction motor drive with a high output of voltage and current to reduce the number of batteries used and in turn reduce the vehicle’s weight. In this paper compared two single Phase BuckBoost Inverter (SPBBI, that is between the SPBBI conventional topology with SPBBI new topology uses a buffer inductor. The results of comparison are expected that the new inverter topology can strengthen the voltage greater than the conventional inverter topology. The inverter’s components of capacitor and inductor were reconfigured. The circuit was simulated for various carrier and signal frequencies with various load. The simulation results of the proposed topology compared with the simulation results of conventional topologies commonly used in a variety of frequency and load values. It is shown that the output voltage and current can be strengthened significantly, with a value of more than five times of the output voltage compared to the conventional inverter. The new inverter topology is useful to be implemented for the electric vehicle.
Field-circuit analysis and measurements of a single-phase self-excited induction generator
Makowski, Krzysztof; Leicht, Aleksander
2017-12-01
The paper deals with a single-phase induction machine operating as a stand-alone self-excited single-phase induction generator for generation of electrical energy from renewable energy sources. By changing number of turns and size of wires in the auxiliary stator winding, an improvement of performance characteristics of the generator were obtained as regards no-load and load voltage of the stator windings as well as stator winding currents of the generator. Field-circuit simulation models of the generator were developed using Flux2D software package for the generator with shunt capacitor in the main stator winding. The obtained results have been validated experimentally at the laboratory setup using the single-phase capacitor induction motor of 1.1 kW rated power and 230 V voltage as a base model of the generator.
Benchmarking of grid fault modes in single-phase grid-connected photovoltaic systems
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang
2012-01-01
Pushed by the booming installations of single-phase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of low voltage ride-through (LVRT) and the grid support...... capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single...... phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant detection and control strategies are discussed. Some faulty modes are studied experimentally...
Analisis Harmonisa Inverter PWM Satu Fasa
Rejeki Simanjorang
2008-01-01
Pada tesis ini dianalisis harmonisa inverter PWM satu fasa. Inverter PWM satu fasa yang akan ditinjau adalah inverter satu fasa jembatan penuh (konvensional) dan inverter komposit. Analisis difokuskan pada penentuan pola penyaklaran yang optimum agar pembangkitan harmonisa dan switching losses inverter rendah. Untuk menentukan pola penyaklaran optimum maka dilakukan analisis yang berbasis pada rangkaian ekivalen harmonisa inverter satu fasa. Dengan menggunakan pola penyaklaran optimum, kedua ...
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2013-01-01
Single-phase transformerless Photovoltaic (PV) inverters are synthesized by combining available solutions in terms of the power section topology, power semiconductors manufacturing technology and structure of the output filter. A design method is presented in this paper for optimizing the power...... semiconductors type (Si- or SiC-based), switching frequency and output filter (LCL- or LLCL-type) employed in H5 and Conergy-NPC PV inverters, considering the simultaneous impact of the factors affecting the PV energy processing performance and PV inverter cost. According to the design results, the optimized Si......-based counterparts will enhance the economic superiority of the resulting optimized H5 and Conergy-NPC PV inverters with respect to the cost of the electricity they generate....
DEFF Research Database (Denmark)
Guan, Pengyu; Da Ros, Francesco; Lillieholm, Mads
2016-01-01
We demonstrate simultaneous phase regeneration of 16-WDM DPSK channels using optical Fourier transformation and a single phase-sensitive amplifier. The BERs of 16-WDM×10-Gbit/s phase noise degraded DPSK signals are improved by 0.4-1.3 orders of magnitude......We demonstrate simultaneous phase regeneration of 16-WDM DPSK channels using optical Fourier transformation and a single phase-sensitive amplifier. The BERs of 16-WDM×10-Gbit/s phase noise degraded DPSK signals are improved by 0.4-1.3 orders of magnitude...
Single-phase power distribution system power flow and fault analysis
Halpin, S. M.; Grigsby, L. L.
1992-01-01
Alternative methods for power flow and fault analysis of single-phase distribution systems are presented. The algorithms for both power flow and fault analysis utilize a generalized approach to network modeling. The generalized admittance matrix, formed using elements of linear graph theory, is an accurate network model for all possible single-phase network configurations. Unlike the standard nodal admittance matrix formulation algorithms, the generalized approach uses generalized component models for the transmission line and transformer. The standard assumption of a common node voltage reference point is not required to construct the generalized admittance matrix. Therefore, truly accurate simulation results can be obtained for networks that cannot be modeled using traditional techniques.
Soft-Switched Neutral-Point-Clamped Single-Phase Boost Rectifier
Itoh, Ryozo; Ishizaka, Kouichi
A soft-switched neutral-point-clamped single-phase boost rectifier capable of compensating the imbalance load voltage is studied. This is based on a single-phase rectifier, in which an inductor is placed in series with the AC supply to resonate with a capacitor connected across the DC output of a full-bridge rectifier and the switching transition is mainly governed by a series resonance. The experimental prototype using insulated-gate bipolar transistors is implemented to investigate the operation under the charge control. The experimental results confirm that the rectifier has a neutral-point-clamp feature providing a good quality AC current.
Transformerless PV inverters. Final report
Energy Technology Data Exchange (ETDEWEB)
Borup, U.
2009-12-15
Since the start of the project the market for grid connected PV inverters have developed further. When the project started three - phase inverter were only available in high power systems. The technology developed within this project will enable three phase technology also to be implemented in string inverters for system down to 10 kW. We expect this to be very attractive due to the increased demand for symmetrical feed-in to the grid. The project relevance is therefore high and the sector continues to develop very much driven by technology. Especially the inverter technology is getting a lot of focus. The inverter systems are expected to take a much larger role in supporting the electrical grid in the future. The technology platform developed within the project is prepared to be extended with these utility functionalities. The main results of the project were: 1) A new technology concept for transformer-less inverters has been demonstrated with a number of prototypes. 2) Efficiency above 97,7% has been proven. 3) Efficiency and Maximum power point tracking has been optimized to ensure that almost all energy produced of the panels is transferred to the grid. 4) The platform is developed with a very fast control board, which enables extended functionality as demanding grid supporting functions in the future. Details about cost price and details about the control loop implementation is excluded from the report due to the competitive situation for Danfoss Solar Inverters A/S. (LN)
DEFF Research Database (Denmark)
Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril
2014-01-01
When paralleling multiple inverters that are capable of operating as an island, the inverters typically employ the droop control scheme. Traditional droop control enables the decentralized regulation of the local voltage and frequency of the microgrid by the inverters. The droop method also enabl...... and reduction of the voltage harmonic distortion at the point of common coupling (PCC). Experimental results were then presented to show the suitability of the proposed algorithms in achieving reactive power sharing and in improving the voltage harmonic distortion at the PCC....
Grid Connection of Wave Power Farm Using an N-Level Cascaded H-Bridge Multilevel Inverter
Directory of Open Access Journals (Sweden)
Rickard Ekström
2013-01-01
Full Text Available An N-level cascaded H-bridge multilevel inverter is proposed for grid connection of large wave power farms. The point-absorber wave energy converters are individually rectified and used as isolated DC-sources. The variable power characteristics of the wave energy converters are discussed, and a method of mitigating this issue is demonstrated. The complete power control system is given in detail and has been experimentally verified for a single-phase setup of the 9-level inverter. Theoretical expressions of the power sharing between multilevel cells are derived and show good correspondence with the experimental results.
Pressure Drop Correlations of Single-Phase and Two-Phase Flow in Rolling Tubes
International Nuclear Information System (INIS)
Xia-xin Cao; Chang-qi Yan; Pu-zhen Gao; Zhong-ning Sun
2006-01-01
A series of experimental studies of frictional pressure drop for single phase and two-phase bubble flow in smooth rolling tubes were carried out. The tube inside diameters were 15 mm, 25 mm and 34.5 mm respectively, the rolling angles of tubes could be set as 10 deg. and 20 deg., and the rolling periods could be set as 5 s, 10 s and 15 s. Combining with the analysis of single-phase water motion, it was found that the traditional correlations for calculating single-phase frictional coefficient were not suitable for the rolling condition. Based on the experimental data, a new correlation for calculating single-phase frictional coefficient under rolling condition was presented, and the calculations not only agreed well with the experimental data, but also could display the periodically dynamic characteristics of frictional coefficients. Applying the new correlation to homogeneous flow model, two-phase frictional pressure drop of bubble flow in rolling tubes could be calculated, the results showed that the relative error between calculation and experimental data was less than ± 25%. (authors)
Hybrid Control Method for a Single Phase PFC using a Low Cost Microcontroller
DEFF Research Database (Denmark)
Jakobsen, Lars Tønnes; Nielsen, Nils; Wolf, Christian
2005-01-01
This paper presents a hybrid control method for single phase boost PFCs. The high bandwidth current loop is analog while the voltage loop is implemented in an 8-bit microcontroller. The design focuses on minimizing the number of calculations done in the microcontroller. A 1kW prototype has been...
Novel Motion Sensorless Control of Single Phase Brushless D.C. PM Motor Drive, with experiments
DEFF Research Database (Denmark)
Lepure, Liviu Ioan; Boldea, Ion; Andreescu, Gheorghe Daniel
2010-01-01
A motion sensorless control for single phase permanent magnet brushless d.c. (PM-BLDC) motor drives, based on flux integration and prior knowledge of the PM flux/position characteristic is proposed here and an adequate correction algorithm is adopted, in order to increase the robustness to noise...
protoDUNE-Single Phase and protDUNE-DualPhase
Brice, Maximilien
2016-01-01
At the EHN1 two big 8m x 8m x8m detector prototypes (protoDUNE-Single Phase and protDUNE-DualPhase) are being constructed. The aim is to test technologies and detector performances for DUNE, a new generation of LBN neutr
A Generic Topology Derivation Method for Single-phase Converters with Active Capacitive DC-links
DEFF Research Database (Denmark)
Wang, Haoran; Wang, Huai; Zhu, Guorong
2016-01-01
capacitive DCDC- link solutions, but important aspects of the topology assess-ment, such as the total energy storage, overall capacitive energy buffer ratio, cost, and reliability are still not available. This paper proposes a generic topology derivation method of single-phase power converters...
Modeling and Control of a Single-Phase Marine Cooling System
DEFF Research Database (Denmark)
Hansen, Michael; Stoustrup, Jakob; Bendtsen, Jan Dimon
2013-01-01
This paper presents two model-based control design approaches for a single-phase marine cooling system. Models are derived from first principles and aim at describing significant system dynamics including nonlinearities and transport delays, while keeping the model complexity low. The two...
Single-Phase Phase-Locked Loop Based on Derivative Elements
DEFF Research Database (Denmark)
Guan, Qingxin; Zhang, Yu; Kang, Yong
2017-01-01
High-performance phase-locked loops (PLLs) are critical for power control in grid-connected systems. This paper presents a new method of designing a PLL for single-phase systems based on derivative elements (DEs). The quadrature signal generator (QSG) is constructed by two DEs with the same...
A re-look at critical factors influencing single-phase formation of Ba2 ...
Indian Academy of Sciences (India)
Home; Journals; Bulletin of Materials Science; Volume 30; Issue 4. A re-look at critical factors influencing single-phase formation of Ba2Ti9O20 microwave dielectrics. Unnikrishnan Gopinath Dhanya Chandran Seema Ansari Bindu Krishnan Rani Panicker Raghu Natarajan. Electrical Properties Volume 30 Issue 4 August ...
Regeneration of phase unlocked serial multiplexed DPSK signals in a single phase sensitive amplifier
DEFF Research Database (Denmark)
Guan, Pengyu; Da Ros, Francesco; Kjøller, Niels-Kristian
2017-01-01
We demonstrate phase-regeneration of phase unlocked OTDM-DPSK serial signals in a single phase sensitive amplifier through optical cross-phase modulation. The BER of an 8×10 Gbit/s OTDM-DPSK signal is improved by 2 orders of magnitude....
Analysis of Variable-Speed Operation of Drives with Single-Phase Machines
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Luděk; Bendl, Jiří
2007-01-01
Roč. 52, č. 2 (2007), s. 139-147 ISSN 0001-7043 R&D Projects: GA ČR GA102/06/0215 Institutional research plan: CEZ:AV0Z20570509 Keywords : single-phase machines * induction machines * variable-speed drives Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Flux Concentration and Pole Shaping in a Single Phase Hybrid Switched Reluctance Motor Drive
DEFF Research Database (Denmark)
Jakobsen, Uffe; Lu, Kaiyuan
2010-01-01
The single phase hybrid switched reluctance motor (HSRM) may be a good candidate for low-cost drives used for pump applications. This paper presents a new design of the HSRM with improved starting torque achieved by stator pole shaping, and a better arrangement of the embedded stator permanent...
Synchronization in single-phase grid-connected photovoltaic systems under grid faults
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2012-01-01
under grid faults. The focus of this paper is put on the benchmarking of synchronization techniques, mainly about phase locked loop (PLL) based methods, in single-phase PV power systems operating under grid faults. Some faulty mode cases are studied at the end of this paper in order to compare...
Nanowire NMOS Logic Inverter Characterization.
Hashim, Yasir
2016-06-01
This study is the first to demonstrate characteristics optimization of nanowire N-Channel Metal Oxide Semiconductor (NW-MOS) logic inverter. Noise margins and inflection voltage of transfer characteristics are used as limiting factors in this optimization. A computer-based model used to produce static characteristics of NW-NMOS logic inverter. In this research two circuit configuration of NW-NMOS inverter was studied, in first NW-NMOS circuit, the noise margin for (low input-high output) condition was very low. For second NMOS circuit gives excellent noise margins, and results indicate that optimization depends on applied voltage to the inverter. Increasing gate to source voltage with (2/1) nanowires ratio results better noise margins. Increasing of applied DC load transistor voltage tends to increasing in decreasing noise margins; decreasing this voltage will improve noise margins significantly.
Development of a single-phase thermosiphon for cold collection and storage of radiative cooling
Energy Technology Data Exchange (ETDEWEB)
Zhao, Dongliang; Martini, Christine Elizabeth; Jiang, Siyu; Ma, Yaoguang; Zhai, Yao; Tan, Gang; Yin, Xiaobo; Yang, Ronggui
2017-11-01
A single-phase thermosiphon is developed for cold collection and storage of radiative cooling. Compared to the conventional nocturnal radiative cooling systems that use an electric pump to drive the heat transfer fluid, the proposed single-phase thermosiphon uses the buoyancy force to drive heat transfer fluid. This solution does not require electricity, therefore improving the net gain of the radiative cooling system. A single-phase thermosiphon was built, which consists of a flat panel, a cold collection tank, a water return tube, and a water distribution tank. Considering that outdoor radiative cooling flux is constantly changing (i.e. uncontrollable), an indoor testing facility was developed to provide a controllable cooling flux (comparable to a radiative cooling flux of 100 W/m2) for the evaluation of thermosiphon performance. The testing apparatus is a chilled aluminum flat plate that has a controlled air gap separation relative to the flat panel surface of the thermosiphon to emulate radiative cooling. With an average of 105 W/m2 cooling flux, the 18 liters of water in the thermosiphon was cooled to an average temperature of 12.5 degrees C from an initial temperature of 22.2 degrees C in 2 h, with a cold collection efficiency of 96.8%. The results obtained have demonstrated the feasibility of using a single-phase thermosiphon for cold collection and storage of radiative cooling. Additionally, the effects of the thermosiphon operation conditions, such as tilt angle of the flat panel, initial water temperature, and cooling energy flux, on the performance have been experimentally investigated. Modular design of the single-phase thermosiphon gives flexibility for its scalability. A radiative cooling system with multiple thermosiphon modules is expected to play an important role in cooling buildings and power plant condensers.
Inverter Ground Fault Overvoltage Testing
Energy Technology Data Exchange (ETDEWEB)
Hoke, Andy [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chebahtah, Justin [SolarCity Corporation, San Mateo, CA (United States); Wang, Trudie [SolarCity Corporation, San Mateo, CA (United States); McCarty, Michael [SolarCity Corporation, San Mateo, CA (United States)
2015-08-12
This report describes testing conducted at NREL to determine the duration and magnitude of transient overvoltages created by several commercial PV inverters during ground fault conditions. For this work, a test plan developed by the Forum on Inverter Grid Integration Issues (FIGII) has been implemented in a custom test setup at NREL. Load rejection overvoltage test results were reported previously in a separate technical report.
Invertibility in L-Topological Spaces
Directory of Open Access Journals (Sweden)
Anjaly Jose
2014-03-01
Full Text Available In this paper, we extend the concept of invertibility to L-topological spaces and delineate its properties. Then, we study further completely invertible L-topological spaces and introduce two types of invertible L-topologies based on the inverting maps, studying their sums, subspaces and simple extensions.
Diagnosis of inverter switch open circuit faults based on neutral point voltage signal analysis
Directory of Open Access Journals (Sweden)
Liwei GUO
Full Text Available Using the current signal to diagnose inverter faults information is apt to be affected by the load, noise and other factors; besides, it requires long diagnosis period with special algorithms and the diagnosis result is easily to be incorrect with no-load or light-load. Focusing on this issue, the logical analysis method is proposed for correlation logical analysis of leg neutral-point voltage and pulse signal to realize the diagnosis of the open circuit faults of inverter switches. The logical expressions of output signals of inverter power tube open-circuit faults is put forward and interrelated hardware circuit design is also elaborated. Delaying the rising edge of inverter power tube's pulse signal can effectively avoid the diagnosis error caused by the power tube's switching on/off. The experiment results show that the method can effectively diagnose the open-circuit faults of single-phase single power tube inverter in real-time and the hardware circuit cost is low, which shows it is effective and feasible.
Energy Technology Data Exchange (ETDEWEB)
Nelson, Austin; Martin, Gregory; Hurtt, James
2017-05-08
As revised interconnection standards for grid-tied photovoltaic (PV) inverters address new advanced grid support functions (GSFs), there is increasing interest in inverter performance in the case of abnormal grid conditions. The growth of GSF-enabled inverters has outpaced the industry standards that define their operation, although recently published updates to UL1741 with Supplement SA define test conditions for GSFs such as volt-var control, frequency-watt control, and volt-age/frequency ride-through, among others. A comparative experimental evaluation has been completed on four commercially available, three-phase PV inverters in the 24.0-39.8 kVA power range on their GSF capability and the effect on abnormal grid condition response. This study examines the impact particular GSF implementations have on run-on times during islanding conditions, peak voltages in load rejection overvoltage scenarios, and peak currents during single-phase and three-phase fault events for individual inverters. This report reviews comparative test data, which shows that GSFs have little impact on the metrics of interest in most tests cases.
An Open-Loop Grid Synchronization Approach for Single-Phase Applications
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez
2018-01-01
in the presence of frequency drifts. This is particularly true in single-phase applications, where the lack of multiple independent input signals makes the implementation of the synchronization technique difficult. The aim of this paper is to develop an effective OLS technique for single-phase power and energy...... applications. The proposed OLS method benefits from a straightforward implementation, a fast dynamic response (a response time less than two cycles of the nominal frequency), and a complete immunity against the DC component in the grid voltage. In addition, the designed OLS method totally blocks (significantly...... attenuates) all harmonics up to the aliasing point under a nominal (off-nominal) frequency. The effectiveness of the designed OLS technique is verified using comparative experimental results....
Single-Phase Hybrid Switched Reluctance Motor for Low-Power Low-Cost Applications
DEFF Research Database (Denmark)
Lu, Kaiyuan; Rasmussen, Peter Omand; Jakobsen, Uffe
2011-01-01
This paper presents a new single-phase, Hybrid Switched Reluctance (HSR) motor for low-cost, low-power, pump or fan drive systems. Its single-phase configuration allows use of a simple converter to reduce the system cost. Cheap ferrite magnets are used and arranged in a special flux concentration...... manner to increase effectively the torque density and efficiency of this machine. The efficiency of this machine is comparable to the efficiency of a traditional permanent magnet machine in the similar power range. The cogging torque, due to the existence of the permanent magnetic field, is beneficially...... used to reduce the torque ripple and enable self-starting of the machine. The starting torque of this machine is significantly improved by a slight extension of the stator pole-arc. A prototype machine and a complete drive system has been manufactured and tested. Results are given in this paper....
Evaluation of 600V Superjunction Devices in Single Phase PFC Applications under CCM Operation
DEFF Research Database (Denmark)
Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.
2014-01-01
This paper pr esents a power density/efficiency evaluation in single phase power factor correction (PFC) applications operating in continuous conduction mode (CCM). The comparison is based on semiconductor dynamic characterization and a mathematical model for prediction of the conducted electroma......This paper pr esents a power density/efficiency evaluation in single phase power factor correction (PFC) applications operating in continuous conduction mode (CCM). The comparison is based on semiconductor dynamic characterization and a mathematical model for prediction of the conducted...... electromagnetic interference (EMI). The dynamic characterization is based on a low inductive double pulse tester (DPT). The measured switching energy is used in order to evaluate the devices performance in a conventional PFC. This data is used together with the mathematical model for prediction of the conducted...... electromagnetic interference. The method allows comparing different devices and evaluating the performance as a function of the PFC power density and efficiency....
DQ reference frame modeling and control of single-phase active power decoupling circuits
DEFF Research Database (Denmark)
Tang, Yi; Qin, Zian; Blaabjerg, Frede
2015-01-01
Power decoupling circuits can compensate the inherent double line frequency ripple power in single-phase systems and greatly facilitate their dc-link capacitor design. Example applications of power decoupling circuit include photovoltaic, light-emitting diode, fuel cell, and motor drive systems....... This paper presents the dq synchronous reference frame modeling of single-phase power decoupling circuits and a complete model describing the dynamics of dc-link ripple voltage is presented. The proposed model is universal and valid for both inductive and capacitive decoupling circuits, and the input...... of decoupling circuits can be either dependent or independent of its front-end converters. Based on this model, a dq synchronous reference frame controller is designed which allows the decoupling circuit to operate in two different modes because of the circuit symmetry. Simulation and experimental results...
Ion beam induced single phase nanocrystalline TiO2 formation
Rukade, Deepti A.; Tribedi, L. C.; Bhattacharyya, Varsha
2014-06-01
Single phase TiO2 nanostructures are fabricated by oxygen ion implantation (60 keV) at fluence ranging from 1×1016 ions/cm2 to 1×1017 ions/cm2 in titanium thin films deposited on fused silica substrate and subsequent thermal annealing in argon atmosphere. GAXRD and Raman spectroscopy study reveals formation of single rutile phases of TiO2. Particle size is found to vary from 29 nm to 35 nm, establishing nanostructure formation. Nanostructure formation is also confirmed by the quantum confinement effect manifested by the blueshift of the UV-vis absorption spectra. Photoluminescence spectra show peaks corresponding to TiO2 rutile phase and reveal the presence of oxygen defects due to implantation. The controlled synthesis of single phase nanostructure is attributed to ion induced defects and post-implantation annealing. It is observed that the size of the nanostructures formed is strongly dependent on the ion fluence.
A New Power Calculation Method for Single-Phase Grid-Connected Systems
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2013-01-01
A new method to calculate average active power and reactive power for single-phase systems is proposed in this paper. It can be used in different applications where the output active power and reactive power need to be calculated accurately and fast. For example, a grid-connected photovoltaic...... system in low voltage ride through operation mode requires a power feedback for the power control loop. Commonly, a Discrete Fourier Transform (DFT) based power calculation method can be adopted in such systems. However, the DFT method introduces at least a one-cycle time delay. The new power calculation...... method, which is based on the adaptive filtering technique, can achieve a faster response. The performance of the proposed method is verified by experiments and demonstrated in a 1 kW single-phase grid-connected system operating under different conditions.Experimental results show the effectiveness...
An efficiency improved single-phase PFC converter for electric vehicle charger applications
DEFF Research Database (Denmark)
Zhu, Dexuan; Tang, Yi; Jin, Chi
2013-01-01
This paper presents an efficiency improved single-phase power factor correction (PFC) converter with its target application to plug-in hybrid electric vehicle (PHEV) charging systems. The proposed PFC converter features sinusoidal input current, three-level output characteristic, and wide range...... of output DC voltage. Moreover, the involved DC/DC buck conversion stage may only need to convert partial input power rather than full scale of input power, and therefore the system overall efficiency can be much improved. Through proper control of the buck converter, it is also possible to mitigate...... the double-line frequency ripple power that is inherent in a single-phase AC/DC system. Both simulation and experimental results are presented to show the effectiveness of this converter....
Benchmarking of Grid Fault Modes in Single-Phase Grid-Connected Photovoltaic Systems
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang
2013-01-01
Pushed by the booming installations of singlephase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of Low Voltage Ride-Through (LVRT) and grid support...... capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single...... phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant synchronization and control strategies are discussed. Some faulty modes are studied experimentally...
100-nm thick single-phase wurtzite BAlN films with boron contents over 10%
Li, Xiaohang
2017-01-11
Growing thicker BAlN films while maintaining single-phase wurtzite structure and boron content over 10% has been challenging. In this study, we report on the growth of 100 nm-thick single-phase wurtzite BAlN films with boron contents up to 14.4% by MOCVD. Flow-modulated epitaxy was employed to increase diffusion length of group-III atoms and reduce parasitic reactions between the metalorganics and NH3. A large growth efficiency of ∼2000 μm mol−1 was achieved as a result. Small B/III ratios up to 17% in conjunction with high temperatures up to 1010 °C were utilized to prevent formation of the cubic phase and maintain wurtzite structure.
Simulation of the phenomenon of single-phase and two-phase natural circulation
International Nuclear Information System (INIS)
Castrillo, Lazara Silveira
1998-02-01
Natural convection phenomenon is often used to remove the residual heat from the surfaces of bodies where the heat is generated e.g. during accidents or transients of nuclear power plants. Experimental study of natural circulation can be done in small scale experimental circuits and the results can be extrapolated for larger operational facilities. The numerical analysis of transients can be carried out by using large computational codes that simulate the thermohydraulic behavior in such facilities. The computational code RELAP5/MOD2, (Reactor Excursion and Leak Analysis Program) was developed by U.S. Nuclear Regulatory Commissions's. Division of Reactor Safety Research with the objective of analysis of transients and postulated accidents in the light water reactor (LWR) systems, including small and large ruptures with loss of coolant accidents (LOCA's). The results obtained by the simulation of single-phase and two-phase natural circulation, using the RELAP5/MOD2, are presented in this work. The study was carried out using the experimental circuit built at the 'Departamento de Engenharia Quimica da Escola Politecnica da Universidade de Sao Paulo'. In the circuit, two experiments were carried out with different conditions of power and mass flow, obtaining a single-phase regime with a level of power of 4706 W and flow of 5.10 -5 m 3 /s (3 l/min) and a two-phase regime with a level of power of 6536 W and secondary flow 2,33.10 -5 m 3 /s (1,4 l/min). The study allowed tio evaluate the capacity of the code for representing such phenomena as well as comparing the transients obtained theoretically with the experimental results. The comparative analysis shows that the code represents fairly well the single-phase transient, but the results for two-phase transients, starting from the nodalization and calibration used for the case single-phase transient, did not reproduce faithfully some experimental results. (author)
Strain-hardening in nano-structured single phase steels: mechanisms and control.
Bouaziz, O; Barbier, D
2012-11-01
The detrimental effect of grain size refinement on the strain hardening is highlighted in single phase steels. A physical based approach for understanding the underlying mechanisms is presented. In order to overcome this limitation a promising metallurgical route exploiting the thermal stability of mechanically induced twins in austenitic steels has been successfully applied to a stainless grade confirming the opportunity to get nano-structured alloys exhibiting high yield stress with high strain-hardening.
A New Synchronous Reference Frame-Based Method for Single-Phase Shunt Active Power Filters
DEFF Research Database (Denmark)
Monfared, Mohammad; Golestan, Saeed; Guerrero, Josep M.
2013-01-01
This paper deals with the design of a novel method in the synchronous reference frame (SRF) to extract the reference compensating current for single-phase shunt active power filters (APFs). Unlike previous works in the SRF, the proposed method has an innovative feature that it does not need the f...... the excellent performance of the suggested approach. Theoretical evaluations are confirmed by experimental results....
Physical investigation of square cylinder array dynamical response under single-phase cross-flow
International Nuclear Information System (INIS)
Longatte, E.; Baj, F.
2014-01-01
Fluid structure interaction and flow-induced vibration in square cylinder arrangement under single-phase incompressible laminar cross flow are investigated in the present paper. Dynamic instability governed by damping generation is studied without any consideration about mixing with turbulence effects. Conservative and non-conservative effects are pointed out and dynamical stability limit sensitivity to physical parameters is analyzed. Finally the influence of key physical parameters on fluid solid dynamics interaction is quantified. (authors)
Decoupling of Fluctuating Power in Single-Phase Systems Through a Symmetrical Half-Bridge Circuit
DEFF Research Database (Denmark)
Tang, Yi; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
Single-phase ac/dc or dc/ac systems are inherently subject to the harmonic disturbance that is caused by the well-known double-line frequency ripple power. This issue can be eased through the installation of bulky electrolytic capacitors in the dc link. Unfortunately, such passive filtering...... power decoupling method, and both the input current and output voltage of the converter can be well regulated even when very small dc-link capacitors are employed....
A re-look at critical factors influencing single-phase formation of Ba2 ...
Indian Academy of Sciences (India)
TECS
BaSnO3, B2O3 etc, single-phase 2: 9 has been achieved through solid-state route (Yu et al 1994; Lin and Robert. 1999; Wang et al 2003). It is recorded in literature that phase pure 2:9 ceramics without any stabilizing agent will result in better material for microwave dielectric applica- tions (Lin et al 1997; Lin and Robert ...
Single-phase DECT with VNCT compared with three-phase CTU in patients with haematuria
Energy Technology Data Exchange (ETDEWEB)
Park, Jung Jae; Park, Byung Kwan; Kim, Chan Kyo [Sungkyunkwan University School of Medicine, Department of Radiology, Samsung Medical Center, Seoul (Korea, Republic of)
2016-10-15
To retrospectively evaluate the diagnostic performance of single-phase dual-energy CT (DECT) with virtual non-contrast CT (VNCT) compared with three-phase CT urography (CTU) in patients with haematuria. A total of 296 patients underwent three-phase CTU (NCT at 120 kVp; nephrographic phase and excretory phase DECTs at 140 kVp and 80 kVp) owing to haematuria. Diagnostic performances of CT scans were compared for detecting urothelial tumours and urinary stones. Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU. Sensitivity and specificity for tumour were 95 % (19/20) and 98.9 % (273/276) on CTU, 95 % (19/20) and 98.2 % (271/276) on nephrographic phase DECT, and 90 % (18/20) and 98.2 % (271/276) on excretory phase DECT (P > 0.1). Of the 148 stones detected on NCT, 108 (73 %) and 100 (67.6 %) were detected on nephrographic phase and excretory phase VNCTs, respectively. The mean size of stones undetected on nephrographic and excretory VNCTs was measured as 1.5 ± 0.5 mm and 1.6 ± 0.6 mm, respectively. The mean DLPs of three-phase CTU, nephrographic phase DECT and excretory phase DECT were 1076 ± 248 mGy . cm, 410 ± 98 mGy . cm, and 360 ± 87 mGy . cm, respectively (P < 0.001). Single-phase DECT has a potential to replace three-phase CTU for detecting tumours with a lower radiation dose. (orig.)
Modeling and analysis of variable speed single phase induction motors with iron loss
International Nuclear Information System (INIS)
Vaez-Zadeh, S.; Zahedi, B.
2009-01-01
Despite their usual low power ratings of single phase induction motors, they consume a considerable part of total motors energy consumption due to their large and ever-increasing quantity. The recent rising of oil prices and environmental crises has fortified the idea of energy saving practices in all applications; particularly in single phase induction motors due to their typical low efficiency. An essential requirement for this practice is the modeling and analysis of machine electrical losses under variable frequency operation. In this paper an improved steady state model of single phase induction motors is derived to investigate major motor characteristics like torque-speed, input power, output power, etc. A special emphasis is placed on accurately representing core losses at variable frequency. The winding currents phase difference is reintroduced as a fundamental motor variable to determine motor performances including losses and efficiency. An advanced computerized motor test setup is designed and built for on-line measurement of motor characteristics at different supply and operating conditions. The extensive experimental results, in good agreement with the simulation results based on the mentioned analysis, confirm the validity of the proposed model.
Directory of Open Access Journals (Sweden)
Pedro Samuel Gomes Medeiros
2011-09-01
Full Text Available This paper makes a comparative analysis of the thermophysical properties of ice slurry with conventional single-phase secondary fluids used in thermal storage cooling systems. The ice slurry is a two-phase fluid consisting of water, antifreeze and ice crystals. It is a new technology that has shown great energy potential. In addition to transporting energy as a heat transfer fluid, it has thermal storage properties due to the presence of ice, storing coolness by latent heat of fusion. The single-phase fluids analyzed are water-NaCl and water-propylene glycol solutions, which also operate as carrier fluids in ice slurry. The presence of ice changes the thermophysical properties of aqueous solutions and a number of these properties were determined: density, thermal conductivity and dynamic viscosity. Data were obtained by software simulation. The results show that the presence of 10% by weight of ice provides a significant increase in thermal conductivity and dynamic viscosity, without causing changes in density. The rheological behavior of ice slurries, associated with its high viscosity, requires higher pumping power; however, this was not significant because higher thermal conductivity allows a lower mass flow rate without the use of larger pumps. Thus, the ice slurry ensures its high potential as a secondary fluid in thermal storage cooling systems, proving to be more efficient than single-phase secondary fluids.
Directory of Open Access Journals (Sweden)
Md Ruhul Amin
2017-12-01
Full Text Available In this paper, a fast self-synchronization known as virtual synchronous converter (VSCon between single-phase microgrid and inverter in low-voltage microgrid, has been developed in Matlab/Simulink. The idea is to any phase locked loop (PLL circuit for inverter-microgrid synchronization in order to improve the synchronization time. As known, it is difficult and lengthy process to tune the PLL gain parameters to reach suitable performance for synchronizing among the voltage, phase-angle and frequency between them. Due to this problem, a fast self synchronization technique is needed in order to minimize the time losses at the microgrid connection. Therefore, the VSCon has been developed which is based on the synchronous generator mathematical model but in virtual environment representation. It has been applied in the inverter control for generating switching pattern to the inverter switches in order to respond to the grid voltage for improve the synchronization. For a prove of concept, several simulation tests in MATLAB models have been conducted, in order to see the effectiveness of this VSCon. First test has been conducted, when a 240V, 50Hz frequency grid source is used for observing the self-synchronization the system with the power flows output. Furthermore, the next test is conducted when the grid frequency is changed from the rated frequency at 50Hz to 51Hz and the result shows the VSCon in inverter control takes nearly 40ms to synchronize to this new frequency value. The test on grid phase-angle delay also been tested when ac grid voltage has 150 phase delay. As from all the results, the improved inverter control with VSCon structure is able to have fast and self-synchronized between the invertergrid connection before the power from the inverter can be transferred.
Directory of Open Access Journals (Sweden)
Mahmoud Salem
2015-12-01
Full Text Available Achieving high reliable grid-connected photovoltaic (PV systems with high power quality and high operation efficiency is highly required for distributed generation units. A double grid-frequency voltage ripple is found on the dc-link voltage in single-phase photovoltaic grid-connected systems due to the unbalance of the instantaneous dc input and ac output powers. This voltage ripple has undesirable effects on the power quality and operational efficiency of the whole system. Harmonic distortion in the injected current to the grid is one of the problems caused by this double grid-frequency voltage ripple. The double grid frequency ripple propagates to the PV voltage and current which disturb the extracted maximum power from the PV array. This paper introduces intelligent solutions towards mitigate the side effects of the double grid-frequency voltage ripple on the transferred power quality and the operational efficiency of single-phase two-stage grid-connected PV system. The proposed system has three control loops: MPPT control loop, dc-link voltage control loop and inverter current control loop. Solutions are introduced for all the three control loops in the system. The current controller cancels the dc-link voltage effect on the total harmonic distortion of the output current. The dc-link voltage controller is designed to generate a ripple free reference current signal that leads to enhance the quality of the output power. Also a modified MPPT controller is proposed to optimize the extracted power from the PV array. Simulation results show that higher injected power quality is achieved and higher efficiency of the overall system is realized.
Accelerating development of advanced inverters :
Energy Technology Data Exchange (ETDEWEB)
Neely, Jason C.; Gonzalez, Sigifredo; Ropp, Michael; Schutz, Dustin
2013-11-01
The high penetration of utility interconnected photovoltaic (PV) systems is causing heightened concern over the effect that variable renewable generation will have on the electrical power system (EPS). These concerns have initiated the need to amend the utility interconnection standard to allow advanced inverter control functionalities that provide: (1) reactive power control for voltage support, (2) real power control for frequency support and (3) better tolerance of grid disturbances. These capabilities are aimed at minimizing the negative impact distributed PV systems may have on EPS voltage and frequency. Unfortunately, these advanced control functions may interfere with island detection schemes, and further development of advanced inverter functions requires a study of the effect of advanced functions on the efficacy of antiislanding schemes employed in industry. This report summarizes the analytical, simulation and experimental work to study interactions between advanced inverter functions and anti-islanding schemes being employed in distributed PV systems.
Inverter design for high frequency power distribution
King, R. J.
1985-01-01
A class of simple resonantly commutated inverters are investigated for use in a high power (100 KW - 1000 KW) high frequency (10 KHz - 20 KHz) AC power distribution system. The Mapham inverter is found to provide a unique combination of large thyristor turn-off angle and good utilization factor, much better than an alternate 'current-fed' inverter. The effects of loading the Mapham inverter entirely with rectifier loads are investigated by simulation and with an experimental 3 KW 20 KHz inverter. This inverter is found to be well suited to a power system with heavy rectifier loading.
Advanced Modular Inverter Technology Development
Energy Technology Data Exchange (ETDEWEB)
Adam Szczepanek
2006-02-04
Electric and hybrid-electric vehicle systems require an inverter to convert the direct current (DC) output of the energy generation/storage system (engine, fuel cells, or batteries) to the alternating current (AC) that vehicle propulsion motors use. Vehicle support systems, such as lights and air conditioning, also use the inverter AC output. Distributed energy systems require an inverter to provide the high quality AC output that energy system customers demand. Today's inverters are expensive due to the cost of the power electronics components, and system designers must also tailor the inverter for individual applications. Thus, the benefits of mass production are not available, resulting in high initial procurement costs as well as high inverter maintenance and repair costs. Electricore, Inc. (www.electricore.org) a public good 501 (c) (3) not-for-profit advanced technology development consortium assembled a highly qualified team consisting of AeroVironment Inc. (www.aerovironment.com) and Delphi Automotive Systems LLC (Delphi), (www.delphi.com), as equal tiered technical leads, to develop an advanced, modular construction, inverter packaging technology that will offer a 30% cost reduction over conventional designs adding to the development of energy conversion technologies for crosscutting applications in the building, industry, transportation, and utility sectors. The proposed inverter allows for a reduction of weight and size of power electronics in the above-mentioned sectors and is scalable over the range of 15 to 500kW. The main objective of this program was to optimize existing AeroVironment inverter technology to improve power density, reliability and producibility as well as develop new topology to reduce line filter size. The newly developed inverter design will be used in automotive and distribution generation applications. In the first part of this program the high-density power stages were redesigned, optimized and fabricated. One of the main
Directory of Open Access Journals (Sweden)
Faa Jeng Lin
2016-11-01
Full Text Available This paper outlines the modeling and controller design of a novel two-stage photovoltaic (PV micro inverter (MI that eliminates the need for an electrolytic capacitor (E-cap and input current sensor. The proposed MI uses an active-clamped current-fed push-pull DC-DC converter, cascaded with a full-bridge inverter. Three strategies are proposed to cope with the inherent limitations of a two-stage PV MI: (i high-speed DC bus voltage regulation using an integrator to deal with the 2nd harmonic voltage ripples found in single-phase systems; (ii inclusion of a small film capacitor in the DC bus to achieve ripple-free PV voltage; (iii improved incremental conductance (INC maximum power point tracking (MPPT without the need for current sensing by the PV module. Simulation and experimental results demonstrate the efficacy of the proposed system.
Waveform control method for mitigating harmonics of inverter systems with nonlinear load
DEFF Research Database (Denmark)
Wang, Haoran; Zhu, Guorong; Fu, Xiaobin
2015-01-01
DC power systems connecting to single-phase DC/AC inverters with nonlinear loads will have their DC sources being injected with AC ripple currents containing a low-frequency component at twice the output voltage frequency of the inverter and also other current harmonics. Such a current may create...... ability of the waveform control method on other coexisting harmonics, while the DC source delivers AC power to a nonlinear load. With the application of the waveform control, the average DC output power is supplied by the DC source, while the other harmonics pulsation power can be confined to the AC side...... (between the capacitors and the AC load). Theoretical analyses and experiment results are provided to explain the operation and the inhibiting ability, and to showcase the performance of the approach in tackling the harmonics. Results validate that the proposed solution can achieve significant mitigation...
A novel amplitude modulated triangular carrier gain linearization technique for SPWM inverter
Directory of Open Access Journals (Sweden)
Ramkumar Subburam
2009-01-01
Full Text Available This paper presents a new method to extend the linearity of the sinusoidal pulse width modulation (SPWM to full range of the pulse dropping region. The proposed amplitude modulated triangular carrier PWM method (AMTCPWM increases the dynamic range of the SPWM control and eliminates the need of nonlinear modulation in the pulse dropping region to reach the square wave boundary. The novel method combines the spectral quality of SPWM with the efficient single-mode linear control. A simple analytical characterization of the exact method is presented and its effectiveness is demonstrated using simulation for the basic single-phase H-bridge inverter circuit. The hardware results of the designed prototype inverter are presented to validate the betterment of the novel scheme. .
single-phase dc phase dc-ac boost converter ac boost converter
African Journals Online (AJOL)
User
supply (UPS) AC motor drives and other power sup systems, need to step-up the DC input voltage. increase the output voltage level in order requirements, DC-DC boost converter is used provide DC bus voltage for PWM inverters. Hence, conventional design always cascades DC and a separate DC-AC converter.
Invertible extensions and growth conditions
Czech Academy of Sciences Publication Activity Database
Badea, C.; Müller, Vladimír
2004-01-01
Roč. 339, - (2004), s. 21-26 ISSN 1631-073X R&D Projects: GA ČR GA201/03/0041; GA AV ČR KSK1019101 Institutional research plan: CEZ:AV0Z1019905 Keywords : invertible extensions * growth conditions Subject RIV: BA - General Mathematics Impact factor: 0.284, year: 2004
Inverting an Introductory Statistics Classroom
Kraut, Gertrud L.
2015-01-01
The inverted classroom allows more in-class time for inquiry-based learning and for working through more advanced problem-solving activities than does the traditional lecture class. The skills acquired in this learning environment offer benefits far beyond the statistics classroom. This paper discusses four ways that can make the inverted…
Directory of Open Access Journals (Sweden)
Krasil'nikova Tatyana
2017-01-01
Full Text Available This paper discusses the problem associated with accidents in the aerial line (AL ultra-high voltage (UHV due to its big length. In lines with a voltage of 500-1150 kV the overwhelming proportion of trips (98% is caused by single-phase short circuit (SPSC. A substantial portion (70% single-phase short circuits is erratic arc accidents which can be successfully eliminated in a high-speed auto-reclosing (HSAR or single-phase auto-reclosing (SPAR. Success single-phase auto-reclosing (SPAR at liquidation by single-phase short circuit (SPSC, on the one hand, is determined by the characteristics of the secondary arc current, and on the other hand the effectiveness of ways to reduce secondary arc current and recovery voltage development. The minimum dead time, at a HSAR it is usually taken as 0.5 s., at single-phase autoreclosing (SPAR it depends on the current value of the arc support is in the range of 0.5-3.0 s. The article shows high efficiency of use single-phase auto reclosing (SPAR at liquidation SPSC in a single-chain AL voltage of 500 kV, the dependence of the bandwidth of transmission in maintaining the dynamic stability from the length of the pause SPAR.
Overload protection system for power inverter
Nagano, S. (Inventor)
1977-01-01
An overload protection system for a power inverter utilized a first circuit for monitoring current to the load from the power inverter to detect an overload and a control circuit to shut off the power inverter, when an overload condition was detected. At the same time, a monitoring current inverter was turned on to deliver current to the load at a very low power level. A second circuit monitored current to the load, from the monitoring current inverter, to hold the power inverter off through the control circuit, until the overload condition was cleared so that the control circuit may be deactivated in order for the power inverter to be restored after the monitoring current inverter is turned off completely.
Inverter for Installations with Intermittent Electricity Production
Ermuraki Iu.; Berzan V.
2016-01-01
A new architecture of the inverter used in the convertion of electric energy generated by renewable energy sources is studied in this paper. The distinctive features of this inverter is the special block which compensates pulsing of the current with double frequency, characteristic for these inverters. The switching of electronic keys is realized using the method TCM In this block, like in the inverter, which assures the switching at the voltages near to zero (ZVC). The proposed algorithm of ...
DEFF Research Database (Denmark)
Senturk, Osman Selcuk; Hava, Ahmet M.
2009-01-01
This paper proposes the Waveform Reconstruction Method (WRM), which is utilized in the single-phase Series Active Filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...... current sampling delay reduction method (SDRM), a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous reference frame based methods. The analytical, simulation, and experimental studies of a 2...
Fabrication of single phase 2D homologous perovskite microplates by mechanical exfoliation
Li, Junze; Wang, Jun; Zhang, Yingjun; Wang, Haizhen; Lin, Gaoming; Xiong, Xuan; Zhou, Weihang; Luo, Hongmei; Li, Dehui
2018-04-01
The two-dimensional (2D) Ruddlesden-Popper type perovskites have attracted intensive interest for their great environmental stability and various potential optoelectronic applications. Fundamental understanding of the photophysical and electronic properties of the 2D perovskites with pure single phase is essential for improving the performance of the optoelectronic devices and designing devices with new architectures. Investigating the optical and electronic properties of these materials with pure single phase is required to obtain pure single phase 2D perovskites. Here, we report on an alternative approach to fabricate (C4H9NH3)2(CH3NH3) n-1Pb n I3n+1 microplates with pure single n-number perovskite phase for n > 2 by mechanical exfoliation. Micro-photoluminescence and absorption spectroscopy studies reveal that the as-synthesized 2D perovskite plates for n > 2 are comprised by dominant n-number phase and small inclusions of hybrid perovskite phases with different n values, which is supported by excitation power dependent photoluminescence. By mechanical exfoliation method, 2D perovskite microplates with the thickness of around 20 nm are obtained, which surprisingly have single n-number perovskite phase for n = 2-5. In addition, we have demonstrated that the exfoliated 2D perovskite microplates can be integrated with other 2D layered materials such as boron nitride, and are able to be transferred to prefabricated electrodes for photodetections. Our studies not only provide a strategy to prepare 2D perovskites with a single n-number perovskite phase allowing us to extract the basic optical and electronic parameters of pure phase perovskites, but also demonstrate the possibility to integrate the 2D perovskites with other 2D layered materials to extend the device’s functionalities.
Reliable Grid Condition Detection and Control of Single-Phase Distributed Power Generation Systems
DEFF Research Database (Denmark)
Ciobotaru, Mihai
to the utility grid but also to sustain it. This thesis was divided into two main parts, namely "Grid Condition Detection" and "Control of Single-Phase DPGS". In the first part, the main focus was on reliable Phase Locked Loop (PLL) techniques for monitoring the grid voltage and on grid impedance estimation...... of the entire system. Regarding the advance control of DPGS, an active damping technique for grid-connected systems using inductor-capacitorinductor (LCL) filters was proposed in the thesis. The method is based on a notch filter, whose stopband can be automatically adjusted in relation with an estimated value...
Design and analysis of sensorless torque optimization for single phase induction motors
International Nuclear Information System (INIS)
Vaez-Zadeh, S.; Payman, A.
2006-01-01
Single phase induction motors are traditionally used in constant speed applications and suffer from unsymmetrical performance. A reliable speed signal can improve their performance and extend their applications as variable speed drives. In this paper, a speed estimation method for these motors is proposed based on a machine model in the stator flux reference frame. The method is examined in a sensorless torque optimization system over a wide operating range. Extensive simulation results prove the validity of the proposed method. Also, the motor performance under the torque optimization system is analyzed
Indirect Control of a low power Single-Phase Active Power Filter
Directory of Open Access Journals (Sweden)
SILVIU EPURE
2010-12-01
Full Text Available This paper deals with a low power, single phase active filter used to compensate nonlinear loads. The filter uses the indirect control method and it is based on a particular connection between filter, polluting load and grid to avoid timeconsuming mathematic operations or signal processing computations and assures good rejection of harmonic currents injected by the nonlinear load into the grid. A scale model was first simulated in Simulink and then physically implemented. The paper presents simulation and experimental results, and highlight problems encountered during experiments.
Pressure drop and heat transfer of lithium single-phase flow under transverse magnetic field
International Nuclear Information System (INIS)
Takahashi, Minoru; Aritomi, Masanori; Inoue, Akira; Matsuzaki, Mitsuo
1996-01-01
Pressure drop and heat transfer characteristics of a lithium single-phase flow in a rectangular channel was investigated experimentally in the presence of a magnetic field. Friction loss coefficient under non-magnetic field and skin friction coefficient under magnetic field agreed well with the Blasius formula and a simple analytical expression, respectively. Nusselt number under non-magnetic field was slightly lower than the correlation by Hartnett and Irvine. Heat transfer was enhanced by increasing magnetic field above the Hartmann number of about 200. (author)
Benchmarking of small-signal dynamics of single-phase PLLs
DEFF Research Database (Denmark)
Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede
2015-01-01
Phase-looked Loop (PLL) is a critical component for the control and grid synchronization of grid-connected power converters. This paper presents a benchmarking study on the small-signal dynamics of three commonly used PLLs for single-phase converters, including enhanced PLL, second......-order generalized integrator based PLL, and the inverse-PLL. First, a unified small-signal model of those PLLs is established for comparing their dynamics. Then, a systematic design guideline for parameters tuning of the PLLs is formulated. To confirm the validity of theoretical analysis, nonlinear time...
Novel Position and Speed Estimator for PM Single Phase Brushless D.C. Motor Drives
DEFF Research Database (Denmark)
Lepure, Liviu I.; Andreescu, Gheorghe-Daniel; Iles, Doris
2010-01-01
A novel position and speed estimator for single phase permanent magnet brushless d.c. (PMBLDC) motor drives, based on flux integration and prior knowledge of ΨPM (θ) is proposed here and an adequate correction algorithm is adopted in order to increase the robustness to noise and to reduce...... the sensitivity to accuracy of flux linkage estimation. A speed and current close loop control is employed based on the Hall signal and the motor is controlled at different speeds in order to validate the proposed estimation algorithm with satisfying results. The position correction effect is analyzed...
Single phase and two-phase flow pressure losses through restrictions, expansions and inserts
International Nuclear Information System (INIS)
Glenat, P.; Solignac, P.
1984-11-01
We give a selection of methods to predict pressure losses through retrictions, expansions and inserts. In single phase flow, we give the classical method based on the one-dimensional momentum and mass balances. In two-phase flow, we propose the method given by Harshe et al. and an empirical approach suggested by Chisholm. We notice the distinction between long and short inserts depends upon wether or not the vena contracta lies within insert. Finally, we propose three correlations to calculate void fraction through the singularities which have been considered [fr
Reaction kinetics of oxygen on single-phase alloys, oxidation of nickel and niobium alloys
International Nuclear Information System (INIS)
Lalauze, Rene
1973-01-01
This research thesis first addresses the reaction kinetics of oxygen on alloys. It presents some generalities on heterogeneous reactions (conventional theory, theory of jumps), discusses the core reaction (with the influence of pressure), discusses the influence of metal self-diffusion on metal oxidation kinetics (equilibrium conditions at the interface, hybrid diffusion regime), reports the application of the hybrid diffusion model to the study of selective oxidation of alloys (Wagner model, hybrid diffusion model) and the study of the oxidation kinetics of an alloy forming a solid solution of two oxides. The second part reports the investigation of the oxidation of single phase nickel and niobium alloys (phase α, β and γ)
Directory of Open Access Journals (Sweden)
Jan Michalik
2006-01-01
Full Text Available This research has been motivated by industrial demand for single phase current-source active rectifier dedicated for reconstruction of older types of dc machine locomotives. This paper presents converters control structure design and simulations. The proposed converter control is based on the mathematical model and due to possible interaction with railway signaling and required low switching frequency employs synchronous PWM. The simulation results are verified by experimental tests performed on designed laboratory prototype of power of 7kVA
Dynamics Assessment of Grid-Synchronization Algorithms for Single-Phase Grid-Connected Converters
DEFF Research Database (Denmark)
Han, Yang; Luo, Mingyu; Guerrero, Josep M.
2015-01-01
and low computational burden. Meanwhile, some other techniques have been proposed to enhance system robustness and stability characteristics. In this paper, a comprehensive comparison among the OSG-based PLLs and the advanced single-phase PLLs is presented when the grid voltage undergoes disturbances......, and the performance comparison of transient response and disturbance rejection capabilities are presented. Finally, the moving average filter (MAF) is applied to enhance steady state and dynamic response of the delayed-type PLL, derivator-based PLL and the complex-coefficient filter (CCF-PLL) under grid frequency...
Dispersed single-phase-step Michelson interferometer for Doppler imaging using sunlight.
Wan, Xiaoke; Ge, Jian
2012-09-15
A Michelson interferometer is dispersed with a fiber array-fed spectrograph, providing 59 Doppler sensing channels using sunlight in the 510-570 nm wavelength region. The interferometer operates at a single-phase-step mode, which is particularly advantageous in multiplexing and data processing compared to the phase-stepping mode of other interferometer spectrometer instruments. Spectral templates are prepared using a standard solar spectrum and simulated interferometer modulations, such that the correlation function with a measured 1D spectrum determines the Doppler shift. Doppler imaging of a rotating cylinder is demonstrated. The average Doppler sensitivity is ~12 m/s, with some channels reaching ~5 m/s.
Improved Performance via the Inverted Classroom
Weinstein, Randy D.
2015-01-01
This study examined student performance in an inverted thermodynamics course (lectures provided by video outside of class) compared to a traditional lecture class. Students in the inverted class performed better on their exams. Students in the bottom third of the inverted course showed the greatest improvement. These bottom third students had a C…
21 CFR 184.1859 - Invert sugar.
2010-04-01
... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Invert sugar. 184.1859 Section 184.1859 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1859 Invert sugar. (a) Invert sugar (CAS Reg. No. 8013-17-0) is an aqueous...
Γ-source Neutral Point Clamped Inverter
DEFF Research Database (Denmark)
Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede
Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...
Multilevel Inverter by Cascading Industrial VSI
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim
2002-01-01
-source inverter that uses three IGBT triphase inverter modules along with an output transformer to obtain a 3 p.u. multilevel output voltage is introduced. The system yields in high-quality multistep voltage with up to 4 levels and low dv/dt, balanced operation of the inverter modules, each supplying a third...
A Nonadaptive Window-Based PLL for Single-Phase Applications
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez
2018-01-01
The rectangular window filter, typically known as the moving average filter (MAF), is a quasi-ideal low-pass filter that has found wide application in designing advanced single-phase phase-locked loops (PLLs). Most often, the MAF is employed as an in-loop filter within the control loop of the sin......The rectangular window filter, typically known as the moving average filter (MAF), is a quasi-ideal low-pass filter that has found wide application in designing advanced single-phase phase-locked loops (PLLs). Most often, the MAF is employed as an in-loop filter within the control loop...... response is avoided. Nevertheless, the PLL implementation complexity considerably increases as MAFs are frequency-adaptive and, therefore, they require an additional frequency detector for estimating the grid frequency. To reduce the implementation complexity while maintaining a good performance, using...... a nonadaptive MAF-based QSG with some error compensators is suggested in this letter. The effectiveness of the resultant PLL, which is briefly called the nonadaptive MAF-based PLL, is verified using experimental results....
A note on similarity in single-phase and porous-medium natural convection
International Nuclear Information System (INIS)
Lyall, H.G.
1981-03-01
The similarity laws for single-phase and porous-medium natural convection are developed. For single-phase flow Nu = Nu(Ra) implies that inertial effects are negligible, while Nu = Nu(Ra.Pr) implies that viscous effects are. The first correlation is adequate for Pr>10, while the second applies for Pr<0.01. For intermediate values of Pr, a more general correlation, Nu = Nu(Ra,Pr) is necessary. For a porous-medium, if inertial effects and dispersion are negligible, Nu* = Nu*(Ra*). However dispersion will only be negligible if the ratio of grain size d to the width of the region L is very small (d/L<< l). If this condition does not hold it is necessary to model d/L. If inertial effects are significant, i.e. the Reynolds number is too large for Darcy's law to apply, a group containing the effective Prandtl number, Pr*, also needs to be modelled for similarity. (author)
Ion beam induced single phase nanocrystalline TiO{sub 2} formation
Energy Technology Data Exchange (ETDEWEB)
Rukade, Deepti A. [Department of Physics, University of Mumbai, Mumbai 400098 (India); Tribedi, L.C. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Bhattacharyya, Varsha, E-mail: varsha.b1.physics@gmail.com [Department of Physics, University of Mumbai, Mumbai 400098 (India)
2014-06-15
Single phase TiO{sub 2} nanostructures are fabricated by oxygen ion implantation (60 keV) at fluence ranging from 1×10{sup 16} ions/cm{sup 2} to 1×10{sup 17} ions/cm{sup 2} in titanium thin films deposited on fused silica substrate and subsequent thermal annealing in argon atmosphere. GAXRD and Raman spectroscopy study reveals formation of single rutile phases of TiO{sub 2}. Particle size is found to vary from 29 nm to 35 nm, establishing nanostructure formation. Nanostructure formation is also confirmed by the quantum confinement effect manifested by the blueshift of the UV–vis absorption spectra. Photoluminescence spectra show peaks corresponding to TiO{sub 2} rutile phase and reveal the presence of oxygen defects due to implantation. The controlled synthesis of single phase nanostructure is attributed to ion induced defects and post-implantation annealing. It is observed that the size of the nanostructures formed is strongly dependent on the ion fluence.
Directory of Open Access Journals (Sweden)
R. Subramanian
2011-01-01
Full Text Available Purpose – The aim of this paper is to optimize the capacitor value of a single phase open well submersible motor operating under extreme voltage conditions using fuzzy logic optimization technique and compared with no-load volt-ampere method. This is done by keeping the displacement angle (a between main winding and auxiliary winding near 90o, phase angle (f between the supply voltage and line current near 0o. The optimization work is carried out by using Fuzzy Logic Toolbox software built on the MATLAB technical computing environment with Simulink software. Findings – The optimum capacitor value obtained is used with a motor and tested for different supply voltage conditions. The vector diagrams obtained from the experimental test results indicates that the performance is improved from the existing value. Originality/value – This method will be highly useful for the practicing design engineers in selecting the optimum capacitance value for single phase induction motors to achieve the best performance for operating at extreme supply voltage conditions.
MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY
Directory of Open Access Journals (Sweden)
V.S. Malyar
2016-06-01
Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.
Energy Technology Data Exchange (ETDEWEB)
Pinheiro, Larissa Cunha; Su, Jian, E-mail: larissa@lasme.coppe.ufrj.br, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenhraria Nuclear; Cotta, Renato Machado, E-mail: cotta@mecanica.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (POLI/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica
2015-07-01
Single phase natural circulation circuits composed of two convective heat exchangers and connecting tubes are important for the passive heat removal from spent fuel pools (SFP). To keep the structural integrity of the stored spent fuel assemblies, continuously cooling has to be provided in order to avoid increase at the pool temperature and subsequent uncovering of the fuel and enhanced reaction between water and metal releasing hydrogen. Decay heat can achieve considerably high amounts of energy e.g. in the AP1000, considering the emergency fuel assemblies, the maximum heat decay will reach 13 MW in the 15th day (Westinghouse Electric Company, 2010). A highly efficient alternative to do so is by means of natural circulation, which is cost-effective compared to active cooling systems and is inherently safer since presents less associated devices and no external work is required. Many researchers have investigated safety and stability aspects of natural circulation loops (NCL). However, there is a lack of literature concerning the improvement of NCL through a standard unified methodology, especially for natural circulation circuits with two heat exchangers. In the present study, a simplified thermal-hydraulic analysis of single phase natural circulation circuit with two heat exchanges is presented. Relevant dimensionless key groups were proposed to for the design and safety analysis of a scaled NCL for the cooling of spent fuel storage pool with convective cooling and heating. (author)
Experimental study of single-phase pressure drops in coarse particle beds
Energy Technology Data Exchange (ETDEWEB)
Clavier, R., E-mail: remi.clavier@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Chikhi, N., E-mail: nourdine.chikhi@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Fichot, F., E-mail: florian.fichot@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Quintard, M., E-mail: Michel.Quintard@imft.fr [Université de Toulouse, Allée Camille Soula, F-31400 Toulouse (France); INPT, UPS, Allée Camille Soula, F-31400 Toulouse (France); IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse (France); CNRS, F-31400 Toulouse (France)
2017-02-15
Motivated by uncertainty reduction in nuclear debris beds coolability, experiments have been conducted on the CALIDE facility in order to investigate single-phase pressure losses in representative debris beds, i.e., high sphericity (>80%) particle beds with small size dispersion (from 1 mm to 10 mm), for which no validated model exists. In this paper, experimental results are presented and analyzed in order to identify a simple correlation for single-phase flow pressure losses generated in this kind of porous media in reflooding flowing conditions, which cover Darcy to weakly turbulent regimes. In the literature, it has been observed that their behavior can be accurately described by a Darcy–Forchheimer law, involving the sum of a linear term and a quadratic non-linear deviation, with respect to the filtration velocity. Expressions for the coefficients of the linear and quadratic terms are determined by assessing the possibility to evaluate equivalent diameters, i.e., characteristic lengths allowing correct predictions of the linear and quadratic terms by the Ergun equation. It has been observed that the Sauter diameter of particles allows a very precise prediction of the linear term, while the quadratic term can be predicted using the product of the Sauter diameter and a sphericity coefficient as an equivalent diameter.
Baidak, Y.; Smyk, V.
2017-08-01
Using as the base the differential equations system which was presented in relative units for generalized electric motor of hermetic refrigeration compressor, mathematical model of the software for dynamic performance calculation of refrigeration machine compressors drive low-power asynchronous motors was developed. Performed on its ground calculations of the basic model of two-phase electric motor drive of hermetic compressor and the proposed newly developed model of the motor with single-phase stator winding, which is an alternative to the industrial motor winding, have confirmed the benefits of the motor with innovative stator winding over the base engine. Given calculations of the dynamic characteristics of compressor drive motor have permitted to determine the value of electromagnetic torque swinging for coordinating compressor and motor mechanical characteristics, and for taking them into consideration in choosing compressor elements construction materials. Developed and used in the process of investigation of refrigeration compressor drive asynchronous single-phase motor mathematical and software can be considered as an element of computer-aided design system for design of the aggregate of refrigeration compression unit refrigerating machine.
Validation of CATHENA MOD-3.5/Rev0 for single-phase water hammer
International Nuclear Information System (INIS)
Beuthe, T.G.
2000-01-01
This paper describes work performed to validate the system thermalhydraulics code CATHENA MOD-3.5c/Rev0 for single-phase water hammer. Simulations were performed and are compared quantitatively against numerical tests and experimental results from the Seven Sisters Water Hammer Facility to demonstrate CATHENA can predict the creation and propagation of pressure waves when valves are opened and closed. Simulations were also performed to show CATHENA can model the behaviour of reflected and transmitted pressure waves at area changes, dead ends, tanks, boundary conditions, and orifices in simple and more complex piping systems. The CATHENA results are shown to calculate pressure and wave propagation speeds to within 0.2% and 0.5% respectively for numerical tests and within 3.3% and 5% for experimental results respectively. These results are used to help validate CATHENA for use in single-phase water hammer analysis. They also provide assurance that the fundamental parameters needed to successfully model more complex forms of water hammer are accounted for in the MOD-3.5c/Rev0 version of CATHENA, and represent the first step in the process to validate the code for use in modelling two-phase water hammer and condensation-induced water hammer. (author)
Fault-tolerant three-level inverter
Edwards, John; Xu, Longya; Bhargava, Brij B.
2006-12-05
A method for driving a neutral point clamped three-level inverter is provided. In one exemplary embodiment, DC current is received at a neutral point-clamped three-level inverter. The inverter has a plurality of nodes including first, second and third output nodes. The inverter also has a plurality of switches. Faults are checked for in the inverter and predetermined switches are automatically activated responsive to a detected fault such that three-phase electrical power is provided at the output nodes.
Neutral Point Clamped Npc Type Multilevel Inverter
Directory of Open Access Journals (Sweden)
Purohit Sadanand Chandrashekhar
2015-08-01
Full Text Available Concept of the multilevel inverter is same as the other inverter which is to converts Direct current DC to Alternating current AC .The inverted current can be at any vital voltage and frequency with the use of pertinent transformers switching and control circuits. From the source like batteries solar panel wind turbine or fuel cell the inverter will convert the DC electricity to AC electricity. In this modern technology Power electronics is very important where it used in a great variety of product. With the high potential in high power for industry multilevel inverter will become most popular for so many applications.
Energy Technology Data Exchange (ETDEWEB)
Rampinelli, Giuliano Arns
2010-12-15
Grid-connected photovoltaic systems directly convert solar energy into electrical energy delivering to the distribution grid a clean and renewable energy. These systems are basically formed by an array of photovoltaic modules and inverters. The inverters are responsible for converting direct current to alternating current. A study of electrical and thermal characteristics of inverters used in grid-connected photovoltaic systems from a theoretical and experimental analysis. The inverters tests were carried out in two stages: the first stage was performed at Solar Energy Lab. of the Federal University of Rio Grande do Sul (UFRGS), Brazil, where it was used a 4,8 kW{sub p} grid-connected photovoltaic system and ten inverters of different manufacturers. The inverters electrical characteristics measured and analyzed were: direct current to alternating current conversion efficiency, maximum power point tracker efficiency, power factor and harmonic distortion in current and voltage. Inverters thermal testing was also conducted and its results are presented ana analyzed. The second stage of the experimental tests was performed at Photovoltaic Solar Energy Lab. at CIEMAT in Spain. It was used 3 kW{sub p} photovoltaic system and seven inverters of different manufacturers. The inverters are single-phase, up to 5 kW and different topologies (high frequency transformer, low frequency transformer and transformerless). The influence of DC voltage input in the behavior of DC to AC conversion efficiency and power factor was analyzed. The results of the tests allowed the development of mathematical models that describe the electrical and thermal behavior of the inverters. The proposed mathematical models were inserted into computer simulation software developed at UFRGS named FVConect. The evolution of the simulation results compared to the experimental results validates the proposed models. The analysis of the behavior of the inverters improves the understanding of the operating os
Integrated Inverter And Battery Charger
Rippel, Wally E.
1988-01-01
Circuit combines functions of dc-to-ac inversion (for driving ac motor in battery-powered vehicle) and ac-to-dc conversion (for charging battery from ac line when vehicle not in use). Automatically adapts to either mode. Design of integrated inverter/charger eliminates need for duplicate components, saves space, reduces weight and cost of vehicle. Advantages in other applications : load-leveling systems, standby ac power systems, and uninterruptible power supplies.
Effective switching frequency multiplier inverter
Su, Gui-Jia; Peng, Fang Z.
2007-08-07
A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.
Single-phase cadmium telluride thin films deposited by electroless electrodeposition
International Nuclear Information System (INIS)
Khrypunov, G.; Klochko, N.; Lyubov, V.; Li, T.; Volkova, N.
2010-01-01
Full text : Today cadmium telluride (CdTe) is a leading base material for the fabrication of thin film solar cells. Equally with the creation of traditional thin film photovoltaic devices on the base of CdTe in recent years several approaches have been investigated to develop solar cells with extremely thin (80-500 nm) CdTe absorber (so-called ηE(eta)-solar cells) that offer the potential to reduce recombination losses in the base layers and thus use low cost materials. Until today the CdTe depositions for the η-solar cells manufacture were performed by vapour phase epitaxy under dynamical vacuum at working temperature 750 degrees Celsium or by electrodeposition in the special electrochemical cell equipped with the potentiostat. Development research of simple and inexpensive method for obtaining of the single-phase stoichiometric cadmium telluride films has required an improvement of the electroless electrodeposition technique, which theretofore was characterized by some disadvantages, namely, the CdTe films were polluted by free tellurium additions and the composition of the films was Cd:Te=55:45. So, for the showing up the synthesis of doped or stoichiometric cadmium telluride films conditions and in order to decide the problem of the deposition of single-phase CdTe layers it was researched the electrochemical processes going during electroless electrolysis in sulfate solutions with different acidities and CdSO 4 concentrations. Some film samples during deposition were illuminated by 500 W halogen lamp. Deposition time was 10-15 min. The phase composition and structure of the deposited films were determined by XRD-method, the average sizes of the crystalline grains in the films were estimated using Debye-Scherer formula. The transmittance spectra of the samples were measured by double beam spectrophotometer in the spectral range of 0.6-1.1 μm. Surface morphology of the films was researched by scanning electron microscopy. By means of analysis of the
Energetics analysis of interstitial loops in single-phase concentrated solid-solution alloys
Wang, Xin-Xin; Niu, Liang-Liang; Wang, Shaoqing
2018-04-01
Systematic energetics analysis on the shape preference, relative stability and radiation-induced segregation of interstitial loops in nickel-containing single-phase concentrated solid-solution alloys have been conducted using atomistic simulations. It is shown that the perfect loops prefer rhombus shape for its low potential energy, while the Frank faulted loops favor ellipse for its low potential energy and the possible large configurational entropy. The decrease of stacking fault energy with increasing compositional complexity provides the energetic driving force for the formation of faulted loops, which, in conjunction with the kinetic factors, explains the experimental observation that the fraction of faulted loops rises with increasing compositional complexity. Notably, the kinetics is primarily responsible for the absence of faulted loops in nickel-cobalt with a very low stacking fault energy. We further demonstrate that the simultaneous nickel enrichment and iron/chromium depletion on interstitial loops can be fully accounted for by their energetics.
On Thermodynamics Problems in the Single-Phase-Lagging Heat Conduction Model
Directory of Open Access Journals (Sweden)
Shu-Nan Li
2016-11-01
Full Text Available Thermodynamics problems for the single-phase-lagging (SPL model have not been much studied. In this paper, the violation of the second law of thermodynamics by the SPL model is studied from two perspectives, which are the negative entropy production rate and breaking equilibrium spontaneously. The methods for the SPL model to avoid the negative entropy production rate are proposed, which are extended irreversible thermodynamics and the thermal relaxation time. Modifying the entropy production rate positive or zero is not enough to avoid the violation of the second law of thermodynamics for the SPL model, because the SPL model could cause breaking equilibrium spontaneously in some special circumstances. As comparison, it is shown that Fourier’s law and the CV model cannot break equilibrium spontaneously by analyzing mathematical energy integral.
Single-phase pump model for analysis of LMFBR heat transport systems
International Nuclear Information System (INIS)
Madni, I.K.; Cazzoli, E.
1978-05-01
A single-phase pump model for transient and steady-state analysis of LMFBR heat transport systems is presented. Fundamental equations of the model are angular momentum balance to determine transient impeller speed and mass balance (including thermal expansion effects) to determine the level of sodium in the pump tank. Pump characteristics are modeled by homologous head and torque relations. All regions of pump operation are represented with reverse rotation allowed. The model also includes option for enthalpy rise calculations and pony motor operation. During steady state, the pump operating speed is determined by matching required head with total load in the circuit. Calculated transient results are presented for pump coastdown and double-ended pipe break accidents. The report examines the influence of frictional torque and specific speed on predicted response for the pump coastdown to natural circulation transient. The results for a double-ended pipe break accident indicate the necessity of including all regions of operation for pump characteristics
Single-phase sodium pump model for LMFBR thermal-hydraulic analysis
International Nuclear Information System (INIS)
Madni, I.K.; Cazzoli, E.G.; Agrawal, A.K.
1979-01-01
A single-phase, homologous pump model has been developed for simulation of safety-related transients in LMFBR systems. Pump characteristics are modeled by homologous head and torque relations encompassing all regimes of operation. These relations were derived from independent model test results with a centrifugal pump of specific speed equal to 35 (SI units) or 1800 (gpm units), and are used to analyze the steady-state and transient behavior of sodium pumps in a number of LMFBR plants. Characteristic coefficients for the polynomials in all operational regimes are provided in a tabular form. The speed and flow dependence of head is included through solutions of the impeller and coolant dynamic equations. Results show the model to yield excellent agreement with experimental data in sodium for the FFTF prototype pump, and with vendor calculations for the CRBR pump. A sample pipe rupture calculation is also performed to demonstrate the necessity for modeling the complete pump characteristics
Analytical Determining Of The Steinmetz Equivalent Diagram Elements Of Single-Phase Transformer
Directory of Open Access Journals (Sweden)
T. Aly Saandy
2015-08-01
Full Text Available This article presents to an analytical calculation methodology of the Steinmetz Equivalent Diagram Elements applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active and reactive powers consumed by the core are expressed analytically in function of the electromagnetic parameters as resistivity permeability and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The equivalent diagram elements empirically determined by Steinmetz are analytically expressed using the expressions of the no loaded transformer consumptions. To verify the relevance of the model validations both by simulations with different powers and measurements were carried out to determine the resistance and reactance of the core. The obtained results are in good agreement with the theoretical approach and the practical results.
Directory of Open Access Journals (Sweden)
T. Aly Saandy
2015-08-01
Full Text Available Abstract This article presents to an analytical calculation methodology of the Steinmetz coefficient applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active power consumed by the core is expressed analytically in function of the electrical parameters as resistivity and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The required coefficient is identified from the empirical Steinmetz data based on the experimented active power expression. To verify the relevance of the model validations both by simulations with two in two different frequencies and measurements were carried out. The obtained results are in good agreement with the theoretical approach and the practical results.
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
.g. Germany and Italy. Those advanced features can be provided by next generation PV systems, and will be enhanced in the future to ensure an even efficient and reliable utilization of PV systems. In light of this, Reactive Power Injection (RPI) strategies for single-phase PV systems are explored...... like what the conventional power plants do today in the grid regulation participation. Requirements of ancillary services like Low-Voltage Ride-Through (LVRT) associated with reactive current injection and voltage support through reactive power control, have been in effectiveness in some countries, e...... in this paper. The RPI possibilities are: a) constant average active power control, b) constant active current control, c) constant peak current control and d) thermal optimized control strategy. All those strategies comply with the currently active grid codes, but are with different objectives. The proposed...
DEFF Research Database (Denmark)
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
. Those advanced features can be provided by next-generation PV systems, and will be enhanced in the future to ensure an even efficient and reliable utilization of PV systems. In the light of this, Reactive Power Injection (RPI) strategies for single-phase PV systems are explored in this paper. The RPI...... like what the conventional power plants do today in the grid regulation participation. Requirements of ancillary services like Low-Voltage Ride-Through (LVRT) associated with reactive current injection and voltage support through reactive power control, have been in effectiveness in some countries...... possibilities are: a) constant average active power control, b) constant active current control, c) constant peak current control and d) thermal optimized control strategy. All those strategies comply with the currently active grid codes, but are with different objectives. The thermal optimized control strategy...
Abrasion resistance, microhardness and microstructures of single-phase niobium nitride films
International Nuclear Information System (INIS)
Singer, I.L.; Bolster, R.N.; Wolf, S.A.; Skelton, E.F.; Jeffries, R.A.
1983-01-01
The relative abrasive wear resistance of single-phase niobium nitride films deposited at 900 and 500 0 C was measured. Wear resistance versus depth profiles of films abraded against 1-5 μm diamond were obtained by weight loss methods. A β phase Nb 2 N film was five to 20 times more abrasion resistant, but only slightly (40%) harder, than the delta phase NbN films made at the same temperature. The β-Nb 2 N film was deformed plastically during wear, reorienting the [002] c axis perpendicular to the plane of the substrate. The abrasion resistance of the delta-NbN films was initially proportional to the microhardness. Two films had changes in their abrasion resistance as wear proceeded: for one film the change was attributable to deviations in stoichiometry and for the other film it was attributable to increased lattice distortion. (Auth.)
Condition monitoring of shaft of single-phase induction motor using optical sensor
Fulzele, Asmita G.; Arajpure, V. G.; Holay, P. P.; Patil, N. M.
2012-05-01
Transmission type of optical technique is developed to sense the condition of rotating shafts from a distance. A parallel laser beam is passed tangential over the surface of rotating shaft of a single phase induction motor and its flickering shadow is received on a photo sensor. Variations in sensor voltage output are observed on a digital storage oscilloscope. It is demonstrated that this signal carries information about shaft defects like miss alignment, play and impacts in bearings along with surface deformities. Mathematical model of signals corresponding to these shaft defects is developed. During the development and testing of the sensor, effects of reflections are investigated, sensing phenomenon is simulated, frequency response of the sensor is obtained and its performance is compared with conventional accelerometer.
POD-Galerkin Model for Incompressible Single-Phase Flow in Porous Media
Wang, Yi
2017-01-25
Fast prediction modeling via proper orthogonal decomposition method combined with Galerkin projection is applied to incompressible single-phase fluid flow in porous media. Cases for different configurations of porous media, boundary conditions and problem scales are designed to examine the fidelity and robustness of the model. High precision (relative deviation 1.0 x 10(-4)% similar to 2.3 x 10(-1)%) and large acceleration (speed-up 880 similar to 98454 times) of POD model are found in these cases. Moreover, the computational time of POD model is quite insensitive to the complexity of problems. These results indicate POD model is especially suitable for large-scale complex problems in engineering.
Broadband single-phase hyperbolic elastic metamaterials for super-resolution imaging.
Dong, Hao-Wen; Zhao, Sheng-Dong; Wang, Yue-Sheng; Zhang, Chuanzeng
2018-02-02
Hyperbolic metamaterials, the highly anisotropic subwavelength media, immensely widen the engineering feasibilities for wave manipulation. However, limited by the empirical structural topologies, the reported hyperbolic elastic metamaterials (HEMMs) suffer from the limitations of the relatively narrow frequency width, inflexible adjustable operating subwavelength scale and difficulty to further improve the imaging resolution. Here, we show an inverse-design strategy for HEMMs by topology optimization. We design broadband single-phase HEMMs supporting multipolar resonances at different prescribed deep-subwavelength scales, and demonstrate the super-resolution imaging for longitudinal waves. Benefiting from the extreme enhancement of the evanescent waves, an optimized HEMM at an ultra-low frequency can yield an imaging resolution of ~λ/64, representing the record in the field of elastic metamaterials. The present research provides a novel and general design methodology for exploring the HEMMs with unrevealed mechanisms and guides the ultrasonography and general biomedical applications.
Pressure drop characteristics of single-phase flow in vertical rolling pipes
International Nuclear Information System (INIS)
Cao Xiaxin; Yan Changqi; Sun Licheng; Sun Zhongning
2007-01-01
Experimental studies of single-phase pressure drop in rolling pipes were carried out. The inside diameters of three pipes which were fixed on the rolling platform were 15 mm, 25 mm, and 34.5 mm respectively, the rolling periods of the rolling platform could be set as 5s, 10s, 15s, and rolling angles of the rolling platform were 10 degree and 20 degree. The experimental results showed that the frictional factor periodically fluctuated with the time variable, and its amplitude was obviously affected by the change of Reynolds number and pipe diameters. The amplitude and average value of frictional factor both decreased with the increase of Re number, but the bigger the tube diameter was, the larger the amplitude of frictional factor was. At any moment, the transient frictional factor increased with the increase of rolling period. However, the effect of changing rolling angles on the frictional factor was not obvious. (authors)
Vadgama, Rajeshkumar N; Odaneth, Annamma A; Lali, Arvind M
2015-12-01
Isopropyl myristate finds many applications in food, cosmetic and pharmaceutical industries as an emollient, thickening agent, or lubricant. Using a homogeneous reaction phase, non-specific lipase derived from Candida antartica, marketed as Novozym 435, was determined to be most suitable for the enzymatic synthesis of isopropyl myristate. The high molar ratio of alcohol to acid creates novel single phase medium which overcomes mass transfer effects and facilitates downstream processing. The effect of various reaction parameters was optimized to obtain a high yield of isopropyl myristate. Effect of temperature, agitation speed, organic solvent, biocatalyst loading and batch operational stability of the enzyme was systematically studied. The conversion of 87.65% was obtained when the molar ratio of isopropyl alcohol to myristic acid (15:1) was used with 4% (w/w) catalyst loading and agitation speed of 150 rpm at 60 °C. The enzyme has also shown good batch operational stability under optimized conditions.
Rotor Design for an Efficient Single-Phase Induction Motor for Refrigerator Compressors
Directory of Open Access Journals (Sweden)
Hyun-Jin Ahn
2016-03-01
Full Text Available This article describes a rotor making technology for the production of high-efficiency single-phase induction motors (SPIMs to be used in refrigerator compressors. Rotors can have different aluminum fill factors according to the fabrication method. In order to examine the association between the fill factor and the efficiency of the rotor, we analyzed the distribution of magnetic flux density using the finite element method (FEM. Next, we made prototype rotors by conventional casting methods and by the proposed casting method and compared their fill factors. In addition, SPIMs were made using the rotors, and their efficiencies were measured using a dynamometer. Moreover, the SPIMs were put to use in a compressor, for testing, and for each SPIM the refrigerating capacity of the compressor was measured with a calorimeter. Based on the results of the FEM analysis of the magnetic flux density and the experiments, the reliability and validity of the proposed method were proven.
Control of single-phase islanded PV/battery minigrids based on power-line signaling
DEFF Research Database (Denmark)
Quintana, Pablo; Guerrero, Josep M.; Dragicevic, Tomislav
2014-01-01
Power regulation of all converter units in a micro-grid should not be only determined by load demand, but also by the available power of each unit, i.e. a converter fed by a battery. Energy management control is essential in order to handle the variety of prime movers which may include different...... should be utilized as efficiently as possible. This paper proposes a coordinated control strategy based on power-line signaling (PLS), instead of common communications, for a single-phase minigrid in which each unit can operate in different operation modes taking into account the resource limitation....... The whole system is explained ahead and finally, Hardware in the loop results obtained with a dSPACE are presented in order to validate the proposed control strategy....
DEFF Research Database (Denmark)
Zare, Mohammad Hadi; Mohamadian, Mustafa; Wang, Huai
2017-01-01
Microinverters usually connect a PV panel to a Single-phase power grid. In such system, the input power is constant while the output power oscillates twice the line frequency. Thus, the input and output power differences should be stored in a storage component, which is typically an electrolytic...... capacitor. However, electrolytic capacitors are usually blamed for their short lifetime. Recently, some active power decoupling methods are introduced in the literature which can takes advantage of high reliable film capacitors. However, some extra switches and diodes are added to the microinverter which...... can influence the microinverter lifetime. This paper investigates the microinverter reliability according to mission profile where it is installed. To get more accurate results, uncertainties in both lifetime model and manufacturing process are considered. The effect of ambient temperature and solar...
Decoupling of fluctuating power in single-phase systems through a symmetrical half-bridge circuit
DEFF Research Database (Denmark)
Tang, Yi; Blaabjerg, Frede; Loh, Poh Chiang
2014-01-01
Single-phase AC/DC or DC/AC systems inherently subject to harmonic disturbance which is caused by the well-known double line frequency ripple power. This issue can be eased through the installation of bulky electrolytic capacitors in the dc-link, but such passive filtering approach may inevitably...... or film capacitors to store the ripple power, and this again leads to increased component costs. In view of this, this paper presents a symmetrical half-bridge circuit which utilizes the dc-link capacitors to absorb the ripple power, and the only additional components are a pair of switches and a small...... filtering inductor. A design example is presented and the proposed circuit concept is also verified with simulation and experimental results. It shows that at least ten times capacitance reduction can be achieved with the proposed active power decoupling method, which proves its effectiveness....
Pattern formation in single-phase FAC. A stability analysis of an oxide layer
Energy Technology Data Exchange (ETDEWEB)
Zinemanas, Daniel [The Israel Electric Corp., Haifa (Israel). Dept. of Chemistry; Herszage, Amiel [The Israel Electric Corp., Haifa (Israel). Dept. of Energy Technologies Development
2013-03-15
Pattern formation is a salient characteristic of the flow-accelerated corrosion process, particularly in single-phase flow, where a typical ''orange peel'' surface texture is normally formed. The process of such pattern formation is, however, not well understood. In order to gain some insight into the role of the various processes and parameters involved in this process, a linear stability analysis of an oxide layer based on the Sanchez-Caldera model was performed. According to the results obtained in this study, it follows that the oxide layer is stable regarding perturbations of the oxide thickness or the reaction constant, but it is unstable in respect to perturbations of the mass transfer coefficient. These results suggest therefore that the flow, and not local surface in homogeneities, plays a central role in the pattern formation process. (orig.)
Rapid synthesis of single-phase bismuth ferrite by microwave-assisted hydrothermal method
International Nuclear Information System (INIS)
Cao, Wenqian; Chen, Zhi; Gao, Tong; Zhou, Dantong; Leng, Xiaonan; Niu, Feng; Zhu, Yuxiang; Qin, Laishun; Wang, Jiangying; Huang, Yuexiang
2016-01-01
This paper describes on the fast synthesis of bismuth ferrite by the simple microwave-assisted hydrothermal method. The phase transformation and the preferred growth facets during the synthetic process have been investigated by X-ray diffraction. Bismuth ferrite can be quickly prepared by microwave hydrothermal method by simply controlling the reaction time, which is further confirmed by Fourier Transform infrared spectroscopy and magnetic measurement. - Graphical abstract: Single-phase BiFeO 3 could be realized at a shortest reaction time of 65 min. The reaction time has strong influences on the phase transformation and the preferred growth facets. - Highlights: • Rapid synthesis (65 min) of BiFeO 3 by microwave-assisted hydrothermal method. • Reaction time has influence on the purity and preferred growth facets. • FTIR and magnetic measurement further confirm the pure phase.
Compact ASD Topologies for Single-Phase Integrated Motor Drives with Sinusoidal Input Current
DEFF Research Database (Denmark)
Klumpner, Christian; Blaabjerg, Frede; Thoegersen, Paul
2005-01-01
A standard configuration of an Adjustable Speed Drive (ASD) consists of two separate units: an AC motor, which runs with fixed speed when it is supplied from a constant frequency grid voltage and a frequency converter, which is used to provide the motor with variable voltage-variable frequency......-density integration of the converter caused by the large size of the passive components (electrolytic capacitors and iron chokes) and vibration of the converter enclosure. This paper analyzes the implementation aspects for obtaining a compact and cost effective single-phase ASD with sinusoidal input current...... for high frequency operation, higher core losses will occur, but outside the converter enclosure. The advantages are: the reduction of the number of active semiconductor devices, the reduction of the ASD size and the better integration potential....
A Rotor Flux and Speed Observer for Sensorless Single-Phase Induction Motor Applications
Directory of Open Access Journals (Sweden)
Massimo Caruso
2012-01-01
Full Text Available It is usual to find single-phase induction motor (SPIM in several house, office, shopping, farm, and industry applications, which are become each time more sophisticated and requiring the development of efficient alternatives to improve the operational performance of this machine. Although the rotor flux and rotational speed are essential variables in order to optimize the operation of a SPIM, the use of conventional sensors to measure them is not a viable option. Thus, the adoption of sensorless strategies is the more reasonable proposal for these cases. This paper presents a rotor flux and rotational speed observer for sensorless applications involving SPIMs. Computer simulations and the experimental results are used to verify the performance of the proposed observer.
Factors that affect the calibration of turbines in single-phase flow
Energy Technology Data Exchange (ETDEWEB)
Piper, T. C.
1977-05-01
Basic turbine operation in single-phase flow is related. Causes and relative magnitudes of retarding torque are given for two sizes of turbines when used for water flow measurement. An equation for slip caused by retarding torques is given. Evaluation of turbine slip behavior at the turbine low flow region shows that bearing retarding torques, change in flow patterns, or other effects can predominate in the relatively large changes in the calibration ''constant'' that occurs there. Fluid lubricity is singled out as an important fluid property in certain types of bearings and flow. Temperature induced changes in turbine size are shown to cause calibration changes if a turbine is used at a temperature significantly different than that at which it was calibrated.
Factors that affect the calibration of turbines in single-phase flow
International Nuclear Information System (INIS)
Piper, T.C.
1977-05-01
Basic turbine operation in single-phase flow is related. Causes and relative magnitudes of retarding torque are given for two sizes of turbines when used for water flow measurement. An equation for slip caused by retarding torques is given. Evaluation of turbine slip behavior at the turbine low flow region shows that bearing retarding torques, change in flow patterns, or other effects can predominate in the relatively large changes in the calibration ''constant'' that occurs there. Fluid lubricity is singled out as an important fluid property in certain types of bearings and flow. Temperature induced changes in turbine size are shown to cause calibration changes if a turbine is used at a temperature significantly different than that at which it was calibrated
Single-phase pressure-drop measurements over low void reactivity fuel
International Nuclear Information System (INIS)
Senaratne, U.P.M.; Leung, L.K.H.; Doria, F.J.; Lau, J.H.
2006-01-01
An experiment has been performed to obtain pressure-drop measurements over Low Reactivity Fuel (LVRF) bundles in Refrigerant-134a flow. Production LVRF bundles inserted into the test station with either an uncrept or a 5.1% crept flow channel. For comparison purposes, several production Bruce 37-element bundles were also included in the test string. Overall, the single-phase pressure drop of the LVRF bundle is slightly higher than that Bruce 37-element bundle. Pressure-drop measurements were used to derive bundle and loss coefficients for hydraulic calculations in safety analyses. Applying these loss coefficients, an assessment showed that the overall pressure drop over a string of 12 LVRF bundles (after conversion) remains less than that over a string of 13 Bruce 37-element fuel bundles (before conversion) at the Bruce Nuclear Generating Station. (author)
Calculation of single phase AC and monopolar DC hybrid corona effects
International Nuclear Information System (INIS)
Zhao, T.; Sebo, S.A.; Kasten, D.G.
1996-01-01
Operating a hybrid HVac and HVdc line is an option for increasing the efficiency of power transmission and overcoming the difficulties in obtaining a new right-of-way. This paper proposes a new calculation method for the study of hybrid line corona. The proposed method can be used to calculate dc corona losses and corona currents in dc or ac conductors for single phase ac and monopolar dc hybrid lines. Profiles of electric field strength and ion current density at ground level can be estimated. The effects of the presence of an energized ac conductor on dc conductor corona and dc voltage on ac conductor corona are included in the method. Full-scale and reduced-scale experiments were utilized to investigate the hybrid line corona effects. Verification of the proposed calculation method is given
Hybrid Three-Phase/Single-Phase Microgrid Architecture with Power Management Capabilities
DEFF Research Database (Denmark)
Sun, Qiuye; Zhou, Jianguo; Guerrero, Josep M.
2015-01-01
With the fast proliferation of single-phase distributed generation (DG) units and loads integrated into residential microgrids, independent power sharing per phase and full use of the energy generated by DGs have become crucial. To address these issues, this paper proposes a hybrid microgrid...... control of load power sharing among phases, as well as to allow fully utilization of the energy generated by DGs. Meanwhile, the method combining the modified adaptive backstepping-sliding mode control approach and droop control is also proposed to design the SPBTB system controllers. With the application...... of the proposed PSU and its power management strategy, the loads among different phases can be properly supplied and the energy can be fully utilized as well as obtaining better load sharing. Simulation and experimental results are provided to demonstrate the validity of the proposed hybrid microgrid structure...
Comparative study of Nusselt number for a single phase fluid flow using plate heat exchanger
Directory of Open Access Journals (Sweden)
Shanmugam Rajasekaran
2016-01-01
Full Text Available In this study, the plate heat exchangers are used for various applications in the industries for heat exchange process such as heating, cooling and condensation. The performance of plate heat exchanger depends on many factors such as flow arrangements, plate design, chevron angle, enlargement factor, type of fluid used, etc. The various Nusselt number correlations are developed by considering that the water as a working fluid. The main objective of the present work is to design the experimental set-up for a single phase fluid flow using plate heat exchanger and studied the heat transfer performance. The experiments are carried out for various Reynolds number between 500 and 2200, the heat transfer coefficients are estimated. Based on the experimental results the new correlation is developed for Nusselt number and compared with an existing correlation.
Scaling analysis for the ocean motions in single phase natural circulation
International Nuclear Information System (INIS)
Yan, B.H.; Wen, Q.L.
2015-01-01
Highlights: • The scaling criteria for ocean motions are obtained. • The optimization and selection of the scaling criteria is also analyzed. • The oscillating period in experiments is determined by the time scale. - Abstract: The effects of ocean motions should be analyzed properly in order to guarantee the safety margin of facilities in the engineering design of floating nuclear reactor system. The scaling analysis for the ocean motions in single phase natural circulation is performed. The scaling criteria for both single ocean motions and compound ocean motions are obtained. The selection and optimization of scaling criteria is also analyzed. The oscillating amplitude in experiments should be kept to be identical to that in actual ocean motions. The oscillating period is determined by the time scale. The length scale, oscillating period and experimental power should be taken into consideration synthetically to obtain a reasonable experimental period
Wang, Xu; Gao, Zhensen; Kataoka, Nobuyuki; Wada, Naoya
2010-05-10
A novel scheme using single phase modulator for simultaneous time domain spectral phase encoding (SPE) signal generation and DPSK data modulation is proposed and experimentally demonstrated. Array- Waveguide-Grating and Variable-Bandwidth-Spectrum-Shaper based devices can be used for decoding the signal directly in spectral domain. The effects of fiber dispersion, light pulse width and timing error on the coding performance have been investigated by simulation and verified in experiment. In the experiment, SPE signal with 8-chip, 20GHz/chip optical code patterns has been generated and modulated with 2.5 Gbps DPSK data using single modulator. Transmission of the 2.5 Gbps data over 34km fiber with BEROCDMA) and secure optical communication applications. (c) 2010 Optical Society of America.
Directory of Open Access Journals (Sweden)
Wilk Andrzej
2017-03-01
Full Text Available This paper presents the mathematical model of a single-phase multi-winding core type transformer taking into account magnetic hysteresis phenomenon based on the feedback Preisach model (FPM. The set of loop differential equations was developed for a K-th winding transformer model where the flux linkages of each winding includes flux Φ common to all windings as a function of magneto motive force Θ of all windings. The first purpose of this paper is to implement a hysteresis nonlinearity involved in the Φ(Θ function which also accounts residual magnetic flux. The second purpose of this paper is experimental validation of the developed transformer model in a capacitor discharge test and several different values of residual magnetic flux.
Effects of rolling on single-phase water forced convective heat transfer characteristics
International Nuclear Information System (INIS)
Guo Yanming; Gao Puzhen; Huang Zhen
2010-01-01
A series of single-phase forced circulation tests in a vertical tube with rolling motion were performed in order to investigate effects of rolling motion on thermal-hydraulic characteristics. The amplitudes of the rolling motion in the tests were 10 degree, 15 degree and 20 degree. The rolling periods were 7.5 s, 10 s, 15 s and 20 s. The Reynolds number was from 6000 to 15000. Heat transfer in the test tube is bated by the rolling motion. As the test-bed rolling more acutely, the heat transfer coefficient of the test tube becomes smaller when the mass flow rate in the test tube is a constant. The heat transfer coefficient calculated by the formula which is for stable state doesn't fit very well with that from experiments. At last a formula for calculating heat transfer in rolling motion was introduced. (authors)
A Robust DC-Split-Capacitor Power Decoupling Scheme for Single-Phase Converter
DEFF Research Database (Denmark)
Yao, Wenli; Loh, Poh Chiang; Tang, Yi
2017-01-01
, instead of the usual single dc-link capacitor bank. Methods for regulating this power decoupler have earlier been developed, but almost always with equal capacitances assumed for forming the dc-split capacitor, even though it is not realistic in practice. The assumption should, hence, be evaluated more......Instead of bulky electrolytic capacitors, active power decoupling circuit can be introduced to a single-phase converter for diverting second harmonic ripple away from its dc source or load. One possible circuit consists of a half-bridge and two capacitors in series for forming a dc-split capacitor...... thoroughly, especially when it is shown in the paper that even a slight mismatch can render the power decoupling scheme ineffective and the IEEE 1547 standard to be breached. A more robust compensation scheme is, thus, needed for the dc-split capacitor circuit, as proposed and tested experimentally...
Zero-voltage ride-through capability of single-phase grid-connected photovoltaic systems
DEFF Research Database (Denmark)
Zhang, Zhen; Yang, Yongheng; Ma, Ruiqing
2017-01-01
Distributed renewable energy systems play an increasing role in today’s energy paradigm. Thus, intensive research activities have been centered on improving the performance of renewable energy systems, including photovoltaic (PV) systems, which should be of multiple-functionality. That is, the PV...... systems should be more intelligent in the consideration of grid stability, reliability, and fault protection. Therefore, in this paper, the performance of single-phase grid-connected PV systems under an extreme grid fault (i.e., when the grid voltage dips to zero) is explored. It has been revealed...... that combining a fast and accurate synchronization mechanism with appropriate control strategies for the zero-voltage ride-through (ZVRT) operation is mandatory. Accordingly, the representative synchronization techniques (i.e., the phase-locked loop (PLL) methods) in the ZVRT operation are compared in terms...
Single-phase dual-energy CT urography in the evaluation of haematuria.
Ascenti, G; Mileto, A; Gaeta, M; Blandino, A; Mazziotti, S; Scribano, E
2013-02-01
To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic-excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic-excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Single-phase DECT urography with synchronous nephrographic-excretory phase enhancement represents an accurate "all-in-one'' approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol. Copyright © 2012 The Royal College of Radiologists. All rights reserved.
Single-phase dual-energy CT urography in the evaluation of haematuria
International Nuclear Information System (INIS)
Ascenti, G.; Mileto, A.; Gaeta, M.; Blandino, A.; Mazziotti, S.; Scribano, E.
2013-01-01
Aim: To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic–excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Materials and methods: Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic–excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. Results: The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Conclusion: Single-phase DECT urography with synchronous nephrographic–excretory phase enhancement represents an accurate “all-in-one’’ approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol.
Multi-scale Modeling of Compressible Single-phase Flow in Porous Media using Molecular Simulation
Saad, Ahmed Mohamed
2016-05-01
In this study, an efficient coupling between Monte Carlo (MC) molecular simulation and Darcy-scale flow in porous media is presented. The cell-centered finite difference method with a non-uniform rectangular mesh were used to discretize the simulation domain and solve the governing equations. To speed up the MC simulations, we implemented a recently developed scheme that quickly generates MC Markov chains out of pre-computed ones, based on the reweighting and reconstruction algorithm. This method astonishingly reduces the required computational time by MC simulations from hours to seconds. In addition, the reweighting and reconstruction scheme, which was originally designed to work with the LJ potential model, is extended to work with a potential model that accounts for the molecular quadrupole moment of fluids with non-spherical molecules such as CO2. The potential model was used to simulate the thermodynamic equilibrium properties for single-phase and two-phase systems using the canonical ensemble and the Gibbs ensemble, respectively. Comparing the simulation results with the experimental data showed that the implemented model has an excellent fit outperforming the standard LJ model. To demonstrate the strength of the proposed coupling in terms of computational time efficiency and numerical accuracy in fluid properties, various numerical experiments covering different compressible single-phase flow scenarios were conducted. The novelty in the introduced scheme is in allowing an efficient coupling of the molecular scale and Darcy scale in reservoir simulators. This leads to an accurate description of the thermodynamic behavior of the simulated reservoir fluids; consequently enhancing the confidence in the flow predictions in porous media.
Effects of rolling on characteristics of single-phase water flow in narrow rectangular ducts
International Nuclear Information System (INIS)
Xing Dianchuan; Yan Changqi; Sun Licheng; Xu Chao
2012-01-01
Highlights: ► Mass flow rate and friction pressure drop with different pressure head are compared. ► The effect of pressure head on flow fluctuation is considered theoretically. ► Time-mean and real-time friction pressure drop in different rolling motion are studied. ► Rolling motion influences the fluctuation of friction pressure drop in two aspects. ► New correlation for frictional coefficient in rolling motion is achieved. - Abstract: Experimental and theoretical studies of rolling effects on characteristics of single-phase water flow in narrow rectangular ducts are performed under ambient temperature and pressure. Two types of pressure head are supplied by elevate water tank and pump respectively. The results show that the frictional pressure drop under rolling condition fluctuates periodically, with its amplitude decaying as mean Reynolds number increase and the rolling amplitude decrease, while the amplitude is nearly invariable with rolling period. Rolling motion influences the fluctuation amplitude of frictional pressure drop in two aspects, on the one hand, rolling reduced periodical pulsing flow leads to the fluctuation of the frictional pressure drop, on the other hand, additional force acting on fluid near the wall due to the rolling motion makes local frictional resistance oscillate periodically. The mass flow rate oscillates periodically in rolling motion with the pressure head supplied by water tank, while its fluctuation is so weak that could be neglected for the case of the pressure head supplied by pump. An empirical correlation for the frictional coefficient under rolling condition is achieved, and the experimental data is well correlated. A mathematical model is also developed to study the effect of pressure head on mass flow rate fluctuation in rolling motion. The fluctuation amplitude of the mass flow rate decreases rapidly with a higher pressure head. Comparing with the vertical condition, rolling motion nearly has no effects on
Kimura, Akira
In inverter-converter driving systems for AC electric cars, the DC input voltage of an inverter contains a ripple component with a frequency that is twice as high as the line voltage frequency, because of a single-phase converter. The ripple component of the inverter input voltage causes pulsations on torques and currents of driving motors. To decrease the pulsations, a beat-less control method, which modifies a slip frequency depending on the ripple component, is applied to the inverter control. In the present paper, the beat-less control method was analyzed in the frequency domain. In the first step of the analysis, transfer functions, which revealed the relationship among the ripple component of the inverter input voltage, the slip frequency, the motor torque pulsation and the current pulsation, were derived with a synchronous rotating model of induction motors. An analysis model of the beat-less control method was then constructed using the transfer functions. The optimal setting of the control method was obtained according to the analysis model. The transfer functions and the analysis model were verified through simulations.
Complete Fast Analytical Solution of the Optimal Odd Single-Phase Multilevel Problem
Czech Academy of Sciences Publication Activity Database
Kujan, Petr; Hromčík, Martin; Šebek, Michael
2010-01-01
Roč. 57, č. 7 (2010), s. 2382-2397 ISSN 0278-0046 R&D Projects: GA MŠk(CZ) 1M0567; GA ČR(CZ) GA102/08/0186 Institutional research plan: CEZ:AV0Z10750506 Keywords : Composite sum of powers * Newton's identities * Padé approximation * formal orthogonal polynomials (FOPs) * multilevel (ML) inverters Subject RIV: BC - Control Systems Theory Impact factor: 3.439, year: 2010 http://library.utia.cas.cz/separaty/2010/TR/kujan-0345031.pdf
Cascaded Multicell Trans-Z-Source Inverters
DEFF Research Database (Denmark)
Li, Ding; Chiang Loh, Poh; Zhu, Miao
2013-01-01
Inverters with high-output voltage gain usually face the problem of high-input current flowing through their components. The problem might further be exaggerated if the inverters use high-frequency magnetic devices like transformers or coupled inductors. Leakage inductances of these devices must...... strictly be small to prevent overvoltages caused by switching of their winding currents. To avoid these related problems, cascaded trans-Z-source inverters are proposed. They use multiple magnetic cells in an alternately cascading pattern rather than a single magnetic cell with large turns ratio....... Simulation and experimental results have shown that the multicell inverters can produce the same high-voltage gain, while keeping currents and voltages of the components low. The inverters can also step down their output voltages like a traditional voltage-source inverter without compromising waveform...
Directory of Open Access Journals (Sweden)
Kawa Adam
2014-09-01
Full Text Available The paper treats about main problems of one phase DC-AC microinverters that allow single solar cell to be joined with the grid. One of the issues is to achieve high voltage gain with high efficiency in DC circuit, which is necessary for proper operation of inverter. The operating principles, results of practical implementation and investigations on boost-flyback converter, which meets mentioned demands, are presented. (high step-up DC-DC boost-flyback converter for single phase grid microinverter
Menxi Xie; CanYan Zhu; BingWei Shi; Yong Yang
2017-01-01
High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL) uses a multiplier as phase detector(PD). As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF) applied in-loop of pPLL. The signal characteristic of...
Synthesis of single phase of CuTl-1234 thin films
Khan, N A; Ishida, K; Tateai, F; Kojima, T; Terada, N; Ihara, H
1999-01-01
Thin films of CuTl-1234 superconductor have been prepared for the first time using an amorphous phase epitaxy method (APE). In this method, an amorphous phase is sputtered from a target of stoichiometric composition CuBa/sub 2/Ca/sub 3/Cu/sub 4/O/sub x/. Thin films on the SrTiO/sub 3/ substrate after the thallium treatment are biaxially oriented. The XRD reflected a predominant single phase with c-axis 18.7 AA and pole figure measurements of (103) reflections showed a-axis oriented films with Delta phi =0.8 degrees . Resistivity measurements showed T/sub c/=113 K and preliminary J/sub c/ measurements manifested a current density of 1.0*10/sup 6/ A/cm (77 K, 0 T). The composition of films after EDX measurements is Cu /sub 0.3/Tl/sub 0.7/CuBa/sub 2/Ca/sub 3/Cu/sub 4/O/sub 12-y/. (8 refs).
Single-phased Fault Location on Transmission Lines Using Unsynchronized Voltages
Directory of Open Access Journals (Sweden)
ISTRATE, M.
2009-10-01
Full Text Available The increased accuracy into the fault's detection and location makes it easier for maintenance, this being the reason to develop new possibilities for a precise estimation of the fault location. In the field literature, many methods for fault location using voltages and currents measurements at one or both terminals of power grids' lines are presented. The double-end synchronized data algorithms are very precise, but the current transformers can limit the accuracy of these estimations. The paper presents an algorithm to estimate the location of the single-phased faults which uses only voltage measurements at both terminals of the transmission lines by eliminating the error due to current transformers and without introducing the restriction of perfect data synchronization. In such conditions, the algorithm can be used with the actual equipment of the most power grids, the installation of phasor measurement units with GPS system synchronized timer not being compulsory. Only the positive sequence of line parameters and sources are used, thus, eliminating the incertitude in zero sequence parameter estimation. The algorithm is tested using the results of EMTP-ATP simulations, after the validation of the ATP models on the basis of registered results in a real power grid.
A single-phase model for liquid-feed DMFCs with non-Tafel kinetics
Vera, Marcos
An isothermal single-phase 3D/1D model for liquid-feed direct methanol fuel cells (DMFC) is presented. Three-dimensional (3D) mass, momentum and species transport in the anode channels and gas diffusion layer is modeled using a commercial, finite-volume based, computational fluid dynamics (CFD) software complemented with user supplied subroutines. The 3D model is locally coupled to a one-dimensional (1D) model accounting for the electrochemical reactions in both the anode and the cathode, which provides a physically sound boundary condition for the velocity and methanol concentration fields at the anode gas diffusion layer/catalyst interface. The 1D model - comprising the membrane-electrode assembly, cathode gas diffusion layer, and cathode channel - assumes non-Tafel kinetics to describe the complex kinetics of the multi-step methanol oxidation reaction at the anode, and accounts for the mixed potential associated with methanol crossover, induced both by diffusion and electro-osmotic drag. Polarization curves computed for various methanol feed concentrations, temperatures, and methanol feed velocities show good agreement with recent experimental results. The spatial distribution of methanol in the anode channels, together with the distributions of current density, methanol crossover and fuel utilization at the anode catalyst layer, are also presented for different opperating conditions.
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede
2016-01-01
With a still increase of grid-connected Photovoltaic (PV) systems, challenges have been imposed on the grid due to the continuous injection of a large amount of fluctuating PV power, like overloading the grid infrastructure (e.g., transformers) during peak power production periods. Hence, advanced...... strategies based on: 1) a power control (P-CPG), 2) a current limit method (I-CPG) and 3) the Perturb and Observe algorithm (P&O-CPG). However, the operational mode changes (e.g., from the maximum power point tracking to a CPG operation) will affect the entire system performance. Thus, a benchmarking...... of the proposed CPG strategies is also conducted on a 3-kW single-phase grid-connected PV system. Comparisons reveal that either the P-CPG or I-CPG strategies can achieve fast dynamics and satisfactory steady-state performance. In contrast, the P&OCPG algorithm is the most suitable solution in terms of high...
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede
2018-01-01
With a still increase of grid-connected Photovoltaic (PV) systems, challenges have been imposed on the grid due to the continuous injection of a large amount of fluctuating PV power, like overloading the grid infrastructure (e.g., transformers) during peak power production periods. Hence, advanced...... strategies based on: 1) a power control method (P-CPG), 2) a current limit method (I-CPG) and 3) the Perturb and Observe algorithm (P&O-CPG). However, the operational mode changes (e.g., from the maximum power point tracking to a CPG operation) will affect the entire system performance. Thus, a benchmarking...... of the presented CPG strategies is also conducted on a 3-kW single-phase grid-connected PV system. Comparisons reveal that either the P-CPG or I-CPG strategies can achieve fast dynamics and satisfactory steady-state performance. In contrast, the P&O-CPG algorithm is the most suitable solution in terms of high...
ASSERT validation against the Stern Laboratories' single-phase pressure drop tests
International Nuclear Information System (INIS)
Waddington, G.M.; Kiteley, J.C.; Carver, M.B.
1995-01-01
This paper describes the preliminary validation of ASSERT-IV against the single-phase pressure drop tests from the 37-element CHF (critical heat flux) experiments conducted at Stern Laboratories, and shows how this study fits into the overall ASSERT validation plan. The effects on the pressure drop of several friction and form loss models are evaluated, including the geometry-based K-factor model. The choice of friction factor has a small effect on the predicted channel pressure drop, compared to the form loss model choice. Using the uniform K-factors of Hameed, the computed pressure drops are in excellent agreement with the experimental results from the nominal pressure tube tests. For future ASSERT applications, either Hameed's uniform K-factors or the geometry-based model using Idelchik's thick-edged orifice equation are recommended, as are the friction factor correlations of Colebrook-White, Selander, and Aly and Groeneveld. More analysis of the geometry-based K-factor model is required. (author). 23 refs., 4 tabs., 9 figs
Directory of Open Access Journals (Sweden)
Rajeshkumar N. Vadgama
2015-12-01
Full Text Available Isopropyl myristate finds many applications in food, cosmetic and pharmaceutical industries as an emollient, thickening agent, or lubricant. Using a homogeneous reaction phase, non-specific lipase derived from Candida antartica, marketed as Novozym 435, was determined to be most suitable for the enzymatic synthesis of isopropyl myristate. The high molar ratio of alcohol to acid creates novel single phase medium which overcomes mass transfer effects and facilitates downstream processing. The effect of various reaction parameters was optimized to obtain a high yield of isopropyl myristate. Effect of temperature, agitation speed, organic solvent, biocatalyst loading and batch operational stability of the enzyme was systematically studied. The conversion of 87.65% was obtained when the molar ratio of isopropyl alcohol to myristic acid (15:1 was used with 4% (w/w catalyst loading and agitation speed of 150 rpm at 60 °C. The enzyme has also shown good batch operational stability under optimized conditions.
Design And Development Of An Automatic Single Phase Protective Device Using Ssr
Directory of Open Access Journals (Sweden)
Michael E.
2017-10-01
Full Text Available Since the discovery of energy safety has been a paramount subject matter. This we can see in todays electrical systems where protective devices such as fuse and circuit breakers are used to prevent fire hazards resulting from overload overvoltage and short circuits. However with all the revolution in technology these options may be considered less smart since the fuse made with wire strands calculated for specific current capacity faults permanently when the specified current rating is exceeded. While the circuit breaker which is made up of mechanical switch fails as a result of carbon forming and the wearing away of the contacts because of arcing. As a means of improvement this paper presents the design and development of an automatic single phase protective device using solid state relay SSR. This study is to ensure automatic cut off from power supply in cases of overvoltage above 240 V AC or when overload and short circuit current above 8amps is detected without permanent damage of a fuse placed along current path. Also the design will ensure that there is an automatic close circuit whenever the trigger switch is momentary switch is closed. The system is achieved via the use of PIC micro-controller current sensor and other discrete components. The system is tested and works well inhibiting the frequent faulting of fuses. It also helps to prevent hazard as a result of overvoltage overload and short circuit and ensures a close circuit when the trigger switch is closed.
Single Scattering Detection in Turbin Media Using Single-Phase Structured Illumination Filtering
Berrocal, E.; Johnsson, J.; Kristensson, E.; Alden, M.
2012-05-01
This work shows a unique possibility of visualizing the exponential intensity decay due to light extinction, when laser adiation propagates through a homogeneous scattering edium. This observation implies that the extracted intensity mostly riginates from single scattering events. The filtering of this single light scattering intensity is performed by means of a single-phase structured illumination filtering approach. Results from numerical Monte Carlo simulation confirm the experimental findings for an extinction coefficient of μ_e = 0.36 mm^-1. This article demonstrates an original and reliable way of measuring the extinction coefficient of particulate turbid media based on sidescattering imaging. Such an approach has capabilities to replace the commonly used transmission measurement within the intermediate single-to multiple scattering regime where the optical depth ranges between 1 procedure and set-up. Applications of the technique has potential in probing challenging homogeneous scattering media, such as biomedical tissues, turbid emulsions, etc, in situations where dilution cannot be applied and where conventional transmission measurements fail.
Low-temperature synthesis of single-phase Co7Sb2O12
International Nuclear Information System (INIS)
Brito, M.S.L.; Escote, M.T.; Santos, C.O.P.; Lisboa-Filho, P.N.; Leite, E.R.; Oliveira, J.B.L.; Gama, L.; Longo, E.
2004-01-01
Polycrystalline Co 7 Sb 2 O 12 compounds have been synthesized by a chemical route, which is based on a modified polymeric precursor method. In order to study the physical properties of the samples, X-ray diffraction (XRD), thermal analyses (TG and DSC), infrared spectroscopy (IR), specific surface area (BET), and magnetization measurements were performed on these materials. Characterization through XRD revealed that the samples are single-phase after a heat-treatment at 1100 deg. C for 2 h, while the X-ray patterns of the samples heat-treated at lower temperatures revealed the presence of additional Bragg reflections belonging to the Co 6 Sb 2 O 6 phase. These data were analyzed by means of Rietveld refinement and further analyze showed that Co 7 Sb 2 O 12 displays an inverse spinel crystalline structure. In this structure, the Co 2+ ions occupy the eight tetrahedral positions, and the sixteen octahedral positions are randomly occupied by the Sb 5+ and Co 2+ ions. IR studies disclosed two strong absorption bands, ν 1 and ν 2 , in the expected spectral range for a spinel-type binary oxide with space group Fd3m. Exploratory studies concerning the magnetic properties indicated that this sample presents a spin-glass transition at T f ∼ 64 K
Anaerobic co-digestion of food waste and landfill leachate in single-phase batch reactors
International Nuclear Information System (INIS)
Liao, Xiaofeng; Zhu, Shuangyan; Zhong, Delai; Zhu, Jingping; Liao, Li
2014-01-01
Highlights: • Anaerobic co-digestion strategy for food waste treatment at OLR 41.8 g VS/L. • A certain amount of raw leachate effectively relieved acidic inhibition. • The study showed that food waste was completely degraded. - Abstract: In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH 4 –N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded. We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production
Cost Optimal Design of a Single-Phase Dry Power Transformer
Directory of Open Access Journals (Sweden)
Raju Basak
2015-08-01
Full Text Available The Dry type transformers are preferred to their oil-immersed counterparts for various reasons, particularly because their operation is hazardless. The application of dry transformers was limited to small ratings in the earlier days. But now these are being used for considerably higher ratings. Therefore, their cost-optimal design has gained importance. This paper deals with the design procedure for achieving cost optimal design of a dry type single-phase power transformer of small rating, subject to usual design constraints on efficiency and voltage regulation. The selling cost for the transformer has been taken as the objective function. Only two key variables have been chosen, the turns/volt and the height: width ratio of window, which affects the cost function to high degrees. Other variables have been chosen on the basis of designers’ experience. Copper has been used as conductor material and CRGOS as core material to achieve higher efficiency, lower running cost and compact design. The electrical and magnetic loadings have been kept at their maximum values without violating the design constraints. The optimal solution has been obtained by the method of exhaustive search using nested loops.
Single-phase and two phase bubbly flow in a T connection: theoretical and experimental study
International Nuclear Information System (INIS)
Hervieu, Eric
1988-01-01
The objective of this research thesis is to highlight the driving factors of the separation of phases of a bubbly flow in a T junction, and to develop a prediction model. In a first part, the author reports the rigorous formulation of equations averaged on the T volume. He shows that it's not possible to solve globally the problem with these equations. Then, he reports a bibliographical study on the modelling of a bubbly flow, and, based upon this study, highlights intrinsic characteristics of the flow, and explains its dynamic mechanisms. He reports the development of the theoretical model, and describes the experimental installation used to validate it. In the third part, he reports the study of the liquid-gas interaction, and presents the adopted approach: study of the behaviour of an isolated bubble within a single-phase flow. Experimentation is used to check theoretical predictions. Results are used to compute phase separation. The obtained results are again compared with experimental results to validate the global relevance of the model [fr
Even distribution/dividing of single-phase fluids by symmetric bifurcation of flow channels
International Nuclear Information System (INIS)
Liu, Hong; Li, Peiwen
2013-01-01
Highlights: ► We addressed an issue of distributing a flow to a number of flow channels uniformly. ► The flow distribution is accomplished through bifurcation of channels. ► Some key parameters to the flow distribution uniformity have been identified. ► Flow uniformity was studied for several versions of flow distributor designs. ► A novel fluid packaging device of high efficiency was provided. -- Abstract: This study addresses a fundamental issue of distributing a single-phase fluid flow into a number of flow channels uniformly. A basic mechanism of flow distribution is accomplished through bifurcation of channels that symmetrically split one flow channel into two downstream channels. Applying the basic mechanism, cascades flow distributions are designed to split one flow into a large number of downstream flows uniformly. Some key parameters decisive to the flow distribution uniformity in such a system have been identified, and the flow distribution uniformity of air was studied for several versions of flow distributor designs using CFD analysis. The effect of the key parameters of the flow channel designs to the flow distribution uniformity was investigated. As an example of industrial application, a novel fluid packaging device of high efficiency was proposed and some CFD analysis results for the device were provided. The optimized flow distributor makes a very good uniform flow distribution which will significantly improve the efficiency of fluid packaging. The technology is expected to be of great significance to many industrial devices that require high uniformity of flow distribution
A single-phase model for liquid-feed DMFCs with non-Tafel kinetics
Energy Technology Data Exchange (ETDEWEB)
Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes (Spain)
2007-09-27
An isothermal single-phase 3D/1D model for liquid-feed direct methanol fuel cells (DMFC) is presented. Three-dimensional (3D) mass, momentum and species transport in the anode channels and gas diffusion layer is modeled using a commercial, finite-volume based, computational fluid dynamics (CFD) software complemented with user supplied subroutines. The 3D model is locally coupled to a one-dimensional (1D) model accounting for the electrochemical reactions in both the anode and the cathode, which provides a physically sound boundary condition for the velocity and methanol concentration fields at the anode gas diffusion layer/catalyst interface. The 1D model - comprising the membrane-electrode assembly, cathode gas diffusion layer, and cathode channel - assumes non-Tafel kinetics to describe the complex kinetics of the multi-step methanol oxidation reaction at the anode, and accounts for the mixed potential associated with methanol crossover, induced both by diffusion and electro-osmotic drag. Polarization curves computed for various methanol feed concentrations, temperatures, and methanol feed velocities show good agreement with recent experimental results. The spatial distribution of methanol in the anode channels, together with the distributions of current density, methanol crossover and fuel utilization at the anode catalyst layer, are also presented for different opperating conditions. (author)
Improvements in ANIS and inverted sputter sources
Zwol, N.A. van; Vermeer, A.; Strasters, B.A.
1984-01-01
In this article two sputter sources, i.e. an ANIS and an inverted sputter source are described. The ANIS has been changed into a SNICS-like configuration and measurements of the output current for different sputter target geometries are presented. In the inverted sputter source an immersion lens was
Elimination of the Inrush Current Phenomenon Associated with Single-Phase Offline UPS Systems
Directory of Open Access Journals (Sweden)
Syed Sabir Hussain Bukhari
2016-02-01
Full Text Available Critical load applications always rely on UPS systems to uphold continuous power during abnormal grid conditions. In case of any power disruption, an offline UPS system starts powering the load to avoid blackout. However, this process can root the momentous inrush current for the transformer installed before the load. The consequences of inrush current can be the reduction of output voltage and tripping of protective devices of the UPS system. Furthermore, it can also damage the sensitive load and decrease the transformer’s lifetime. To prevent the inrush current, and to avoid its disruptive effects, this research suggests an offline UPS system based on a current regulated inverter that eliminates the inrush current while powering the transformer coupled loads. A detailed comparative analysis of the conventional and proposed topologies is presented and the experiment was performed by using a small prototype to validate the performance, and operation of the proposed topology.
DEFF Research Database (Denmark)
Liu, Yuan; Wu, Weimin; He, Yuanbin
2016-01-01
A high-order (LCL or LLCL) power filter with a small grid-side inductor is becoming more preferred for a grid-tied inverter due to less total inductance and reduced costs. In a microgrid, the background harmonic voltage (BHV) may distort the injected currents of the grid-tied inverters. In order......-current-feedback AD. Based on this, a single-loop current control with a hybrid damper is proposed for a single-phase LCLor LLCL-filter-based grid-tied inverter. A step-by-step design of the controller method is also introduced in detail. Experiments on a 2-kW prototype fully demonstrate the strong robustness...
Energy Technology Data Exchange (ETDEWEB)
Bolacell, Julio Cezar Oliveira
1987-09-01
This is a study of an inverter circuit for an uninterrupted power supply for computers. A single phase inverter bridge, which uses power transistors and high frequency switching is used (6 khz). To control the load voltage and to reduce the harmonics amplitudes a control circuit is used. This control circuit uses the pulse width modulation technique. Two kinds of PWM systems are shown: first an optimized modulation, characterized by the elimination of certain number of harmonics and second a sinusoidal modulation characterized by the high switching frequency and by the reduction of low order harmonics. With those two kinds of modulation, the study of an L C filter connected to the inverter output is done in order to reduce the harmonics with are in the load. The base drive circuits and their switching power supply studies are shown. Finally a 500 Watt prototype was realized and tested with inductive and resistive load. (author)
Leakage current measurement in transformerless PV inverters
DEFF Research Database (Denmark)
Kerekes, Tamas; Sera, Dezso; Mathe, Laszlo
2012-01-01
Photovoltaic (PV) installations have seen a huge increase during the last couple of years. Transformerless PV inverters are gaining more share of the total inverter market, due to their high conversion efficiency, small weight and size. Nevertheless safety should have an important role in case...... of these tranformerless systems, due to the missing galvanic isolation. Leakage and fault current measurement is a key issue for these inverter topologies to be able to comply with the required safety standards. This article presents the test results of two different current measurement sensors that were suggested...... to be used in commercial PV inverters for the measurement of leakage and fault ground currents. The German VDE0126–1–1 standard gives the limit for fault and leakage ground currents and all grid connected PV inverters have to comply with these limits and disconnect from the grid in case of a fault....
Inverted base pavements: construction and performance
Papadopoulos, Efthymios
2017-05-11
Inverted base pavements involve a well-compacted granular aggregate base built between a thin asphalt concrete layer and a cement-treated base. Inverted base pavements can be constructed using conventional equipment and procedures but require proper quality control. This study reviews the extensive South African experience and case histories in the USA. Accumulating evidence suggests that inverted base pavements are a viable alternative and can outperform conventional pavements at a lower cost. Inverted base pavements rely on the complementary interaction between layers. The cement-treated base provides a stiff foundation for efficient compaction and constrains the deformation of the stress-sensitive granular aggregate base. The thin asphalt surface layer deforms as a membrane and develops low tensile stress. Additional large-scale field tests should be conducted to assess the performance of inverted base pavement designs in a wide range of conditions relevant to the USA.
DEFF Research Database (Denmark)
Li, Qingnan; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2012-01-01
In this paper, a 3.5kW single-phase high efficient interleaved Bridgeless PFC (IBPFC) is proposed for class-D amplifiers. This topology achieves a relatively higher efficiency in a wide output power range, which helps to reduce the energy consuming of the whole system. In addition, a detailed...
Hybrid I-f starting and observer-based Ssnsorless control of single-phase BLDC-PM motor drives
DEFF Research Database (Denmark)
Iepure, Liviu Ioan; Boldea, Ion; Blaabjerg, Frede
2012-01-01
A motion sensorless control for single-phase permanent magnet brushless dc motor based on an I-f starting sequence and a real-time permanent magnet flux estimation is proposed here. The special calculation for extracting the position and speed used here implies the generating of an orthogonal flux......-speed blower-motor (40 W, 10 krpm, 12 Vdc)....
Directory of Open Access Journals (Sweden)
Xingang Fu
2016-04-01
Full Text Available This paper investigates a novel recurrent neural network (NN-based vector control approach for single-phase grid-connected converters (GCCs with L (inductor, LC (inductor-capacitor and LCL (inductor-capacitor-inductor filters and provides their comparison study with the conventional standard vector control method. A single neural network controller replaces two current-loop PI controllers, and the NN training approximates the optimal control for the single-phase GCC system. The Levenberg–Marquardt (LM algorithm was used to train the NN controller based on the complete system equations without any decoupling policies. The proposed NN approach can solve the decoupling problem associated with the conventional vector control methods for L, LC and LCL-filter-based single-phase GCCs. Both simulation study and hardware experiments demonstrate that the neural network vector controller shows much more improved performance than that of conventional vector controllers, including faster response speed and lower overshoot. Especially, NN vector control could achieve very good performance using low switch frequency. More importantly, the neural network vector controller is a damping free controller, which is generally required by a conventional vector controller for an LCL-filter-based single-phase grid-connected converter and, therefore, can overcome the inefficiency problem caused by damping policies.
Low-Complexity Model Predictive Control of Single-Phase Three-Level Rectifiers with Unbalanced Load
DEFF Research Database (Denmark)
Ma, Junpeng; Song, Wensheng; Wang, Xiongfei
2018-01-01
The fluctuation of the neutral-point potential in single-phase three-level rectifiers leads to coupling between the line current regulation and dc-link voltage balancing, deteriorating the quality of line current. For addressing this issue, this paper proposes a low-complexity model predictive...
DEFF Research Database (Denmark)
Ljusev, Petar; Andersen, Michael Andreas E.
2004-01-01
This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...
Natural circulation in single-phase and two-phase flow
International Nuclear Information System (INIS)
Cheung, F.B.; El-Genk, M.S.
1989-01-01
Natural circulation usually arises in a closed loop between a heat source and a heat sink were the fluid motion is driven by density difference. It may also occur in enclosures or cavities where the flow is induced primarily by temperature or concentration gradients within the fluid. The subject has recently received special attention by the heat transfer and nuclear reactor safety communities because of it importance to the areas of energy extraction, decay, heat removal in nuclear reactors, solar and geothermal heating, and cooling of electronic equipment. Although many new results and physical insights have been gained of the various natural circulation phenomena, a number of critical issues remain unresolved. These include, for example, transition from laminar to turbulent flow, buoyancy-induced turbulent flow modeling, change of flow regimes, flow field visualization, variable property effects, and flow instability. This symposium volume contains papers presented in the Natural Circulation in Single-Phase and Two-Phase Flow session at the 1989 Winter Annual Meeting of ASME, by authors from different countries including the United States, Japan, Canada, and Brazil. The papers deal with experimental and theoretical studies as well as state-of-the-art reviews, covering a broad spectrum of topics in natural circulation including: variable-conductance thermosyphons, microelectronic chip cooling, natural circulation in anisotropic porous media and in cavities, heat transfer in flat plat solar collectors, shutdown heat removal in fast reactors, cooling of light-water and heavy-water reactors. The breadth of papers contained in this volume clearly reflect the importance of the current interest in natural circulation as a means for passive cooling and heating
Directory of Open Access Journals (Sweden)
V. S. Malyar
2016-01-01
Full Text Available A mathematical model is developed to study the operation of three-phase asynchronous motor with squirrel-cage rotor when the stator winding is powered from a single phase network. To create a rotating magnetic field one of the phases is fed through the capacitor. Due to the asymmetry of power feed not only transients, but the steady-state regimes are dynamic, so they are described by differential equations in any coordinate system. Their study cannot be carried out with sufficient adequacy on the basis of known equivalent circuits and require the use of dynamic parameters. In the mathematical model the state equations of the circuits of the stator and rotor are composed in the stationary three phase coordinate system. Calculation of the established mode is performed by solving the boundary problem that makes it possible to obtain the coordinate dependences over the period, without calculation of the transient process. In order to perform it, the original nonlinear differential equations are algebraized by approximating the variables with the use of cubic splines. The resulting nonlinear system of algebraic equations is a discrete analogue of the initial system of differential equations. It is solved by parameter continuation method. To calculate the static characteristics as a function of a certain variable, the system is analytically differentiated, and then numerically integrated over this variable. In the process of integration, Newton's refinement is performed at each step or at every few steps, making it possible to implement the integration in just a few steps using Euler's method. Jacobi matrices in both cases are the same. To account for the current displacement in the rods of the squirrel-cage rotor, each of them, along with the squirrel-cage rings, is divided in height into several elements. This results in several squirrel-cage rotor windings which are represented by three-phase windings with magnetic coupling between them.
Multilevel markov chain monte carlo method for high-contrast single-phase flow problems
Efendiev, Yalchin R.
2014-12-19
In this paper we propose a general framework for the uncertainty quantification of quantities of interest for high-contrast single-phase flow problems. It is based on the generalized multiscale finite element method (GMsFEM) and multilevel Monte Carlo (MLMC) methods. The former provides a hierarchy of approximations of different resolution, whereas the latter gives an efficient way to estimate quantities of interest using samples on different levels. The number of basis functions in the online GMsFEM stage can be varied to determine the solution resolution and the computational cost, and to efficiently generate samples at different levels. In particular, it is cheap to generate samples on coarse grids but with low resolution, and it is expensive to generate samples on fine grids with high accuracy. By suitably choosing the number of samples at different levels, one can leverage the expensive computation in larger fine-grid spaces toward smaller coarse-grid spaces, while retaining the accuracy of the final Monte Carlo estimate. Further, we describe a multilevel Markov chain Monte Carlo method, which sequentially screens the proposal with different levels of approximations and reduces the number of evaluations required on fine grids, while combining the samples at different levels to arrive at an accurate estimate. The framework seamlessly integrates the multiscale features of the GMsFEM with the multilevel feature of the MLMC methods following the work in [26], and our numerical experiments illustrate its efficiency and accuracy in comparison with standard Monte Carlo estimates. © Global Science Press Limited 2015.
Single phase flow pressure drop and heat transfer in rectangular metallic microchannels
International Nuclear Information System (INIS)
Sahar, Amirah M.; Özdemir, Mehmed R.; Fayyadh, Ekhlas M.; Wissink, Jan; Mahmoud, Mohamed M.; Karayiannis, Tassos G.
2016-01-01
Numerical simulations were performed using Fluent 14.5 to investigate single phase flow and conjugate heat transfer in copper rectangular microchannels. Two different configurations were simulated: (1) single channel with hydraulic diameter of 0.561 mm and (2) multichannel configuration consisting of inlet and outlet manifolds and 25 channels with hydraulic diameter of 0.409 mm. In the single channel configuration, four numerical models were investigated namely, 2D thin-wall, 3D thin-wall (heated from the bottom), 3D thin-wall (three side heated) and 3D full conjugate models. In the multichannel configuration, only 3D full conjugate model was used. The simulation results of the single channel configuration were validated using experimental data of water as a test fluid while the results of the multichannel configuration were validated using experimental data of R134a refrigerant. In the multichannel configuration, flow distribution among the channels was also investigated. The 3D thin-wall model simulation was conducted at thermal boundary conditions similar to those assumed in the experimental data reduction (uniform heat flux) and showed excellent agreement with the experimental data. However, the results of the 3D full conjugate model demonstrated that there is a significant conjugate effect and the heat flux is not uniformly distributed along the channel resulting in significant deviation compared to the experimental data (more than 50%). Also, the results demonstrated that there is a significant difference between the 3D thin-wall and full conjugate models. The simulation of the multichannel configuration with an inlet manifold having gradual decrease in cross sectional area achieved very reasonable uniform flow distribution among the channels which will provide uniform heat transfer rates across the base of the microchannels.
Single-phase cross-mixing measurements in a 4 x 4 rod bundle
International Nuclear Information System (INIS)
Yloenen, Arto; Bissels, Wilhelm-Martin; Prasser, Horst-Michael
2011-01-01
Highlights: → The wire-mesh sensor technique has been successfully introduced into a fuel rod bundle geometry. → Quantitative information on the turbulent dispersion of the fluid was obtained. → In full spatial and temporal resolution, the data is interesting for the unsteady CFD validation. - Abstract: The wire-mesh sensor technique has been successfully introduced into a fuel rod bundle geometry for the first time. In this context, a dedicated test facility (SUBFLOW) has been designed and constructed at Paul Scherrer Institut (PSI) in a co-operation with the Swiss Federal Institute of Technology (ETH Zuerich). Two wire-mesh sensors designed and built in-house were installed in the upper part of the vertical test section of SUBFLOW, and single-phase experiments on the turbulent mass exchange between neighboring sub-channels were performed. For this purpose, salt tracer was injected locally in one of the sub-channels and conductivity distributions in the bundle measured by the wire-mesh sensor. Both flow rate and distance from the injection point were varied. The latter was achieved by using injection nozzles at different heights. In this way, the sensor located in the upper part of the channel could be used to characterize the progress of the mixing along the flow direction, and the degree of cross-mixing assessed using the quantity of tracer arriving in the neighboring sub-channels. Fluctuations of the tracer concentration in time were used for statistical evaluations, such as the calculation of standard deviations and two-point correlations.
Static Characteristics of the Ferroelectric Transistor Inverter
Mitchell, Cody; Laws, crystal; MacLeond, Todd C.; Ho, Fat D.
2010-01-01
The inverter is one of the most fundamental building blocks of digital logic, and it can be used as the foundation for understanding more complex logic gates and circuits. This paper presents the characteristics of an inverter circuit using a ferroelectric field-effect transistor. The voltage transfer characteristics are analyzed with respect to varying parameters such as supply voltage, input voltage, and load resistance. The effects of the ferroelectric layer between the gate and semiconductor are examined, and comparisons are made between the inverters using ferroelectric transistors and those using traditional MOSFETs.
Switching Characteristics of Ferroelectric Transistor Inverters
Laws, Crystal; Mitchell, Coey; MacLeod, Todd C.; Ho, Fat D.
2010-01-01
This paper presents the switching characteristics of an inverter circuit using a ferroelectric field effect transistor, FeFET. The propagation delay time characteristics, phl and plh are presented along with the output voltage rise and fall times, rise and fall. The propagation delay is the time-delay between the V50% transitions of the input and output voltages. The rise and fall times are the times required for the output voltages to transition between the voltage levels V10% and V90%. Comparisons are made between the MOSFET inverter and the ferroelectric transistor inverter.
Inverted CERN School of Computing
IT Department
2011-01-01
The 5th edition of the Inverted CERN School of Computing (iCSC, “Where students turn into teachers”) will take place next Thursday and Friday (3 and 4 of March) at CERN, Building 31 - IT Amphitheatre - Third Floor. Attendance is free and open to everyone. The programme is designed so that you can attend the lectures that interest you. This year highlights: Cloud Computing, Software Engineering, Cryptography Registration is not mandatory, but will allow you to obtain a copy of the full booklet (first registered, first served). Programme overview: Thursday 3 March 2011 10:00 - 10:15 Introduction School opening 10:15 - 11:10 Lecture 1 Virtualization: what it is, how it works – Luigi Gallerani 11:20 - 12:15 Lecture 2 Server Virtualization at work – Carlos Garcia Fernandez 14:00 - 14:55 Lecture 3 Unweaving Clouds: Principles and Practice – Belmiro Moreira 15:30 - 16:25 Lecture 4 Understanding Cryptography: From Caesar to Public-Key – Nicola...
Directory of Open Access Journals (Sweden)
Wenzhou Lu
2016-01-01
Full Text Available This paper analyzes the general properties of IMP-based controller and presents an internal-model-principle-based (IMP-based specific harmonics repetitive control (SHRC scheme. The proposed SHRC is effective for specific nk±m order harmonics, with n>m≥0 and k=0,1,2,…. Using the properties of exponential function, SHRC can also be rewritten into the format of multiple resonant controllers in parallel, where the control gain of SHRC is n/2 multiple of that of conventional RC (CRC. Therefore, including SHRC in a stable closed-loop feedback control system, asymptotic disturbance eliminating, or reference tracking for any periodic signal only including these specific harmonic components at n/2 times faster error convergence rate compared with CRC can be achieved. Application examples of SHRC controlled three-phase/single-phase grid-connected PWM inverters demonstrate the effectiveness and advantages of the proposed SHRC scheme.
Delta Power Control Strategy for Multi-String Grid-Connected PV Inverters
DEFF Research Database (Denmark)
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede
2016-01-01
With a still increasing penetration level of grid-connected PV systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation, is required...... for grid support (e.g., during frequency deviation). In this paper, a cost-effective solution to realize delta power control for grid-connected PV systems is presented, where the residential/commercial multi-string PV inverter configuration is adopted. This control strategy is a combination of Maximum...... for the entire PV system is achieved. Simulations and experiments have been performed on a 3-kW single-phase grid-connected PV system. The results have confirmed the effectiveness of the delta power control strategy, where the power reserve according to the delta power constraint is achieved under several...
FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters
Sudha, L. U.; Baskaran, J.; Elankurisil, S. A.
2015-01-01
This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results. PMID:25821852
FPGA techniques based new hybrid modulation strategies for voltage source inverters.
Sudha, L U; Baskaran, J; Elankurisil, S A
2015-01-01
This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results.
Transformerless Photovoltaic Inverters Connected to the Grid
DEFF Research Database (Denmark)
Kerekes, Tamas; Teodorescu, Remus; Borup, Uffe
2007-01-01
-phase with respect to the leakage current generation. The best results, both for single-phase and three-phase systems, are obtained when the middle point of the input capacitors is connected to the neutral point, thereby minimizing the voltage fluctuations present at the terminals of the PV panel....
On the prediction of single-phase forced convection heat transfer in narrow rectangular channels
International Nuclear Information System (INIS)
Ghione, Alberto; Noel, Brigitte; Vinai, Paolo; Demazière, Christophe
2014-01-01
In this paper, selected heat transfer correlations for single-phase forced convection are assessed for the case of narrow rectangular channels. The work is of interest in the thermal-hydraulic analysis of the Jules Horowitz Reactor (JHR), which is a research reactor under construction at CEA-Cadarache (France). In order to evaluate the validity of the correlations, about 300 tests from the SULTAN-JHR database were used. The SULTAN-JHR program was carried out at CEA-Grenoble and it includes different kinds of tests for two different vertical rectangular channels with height of 600 mm and gap of 1.51 and 2.16 mm. The experimental conditions range between 2 - 9 bar for the pressure; 0.5 - 18 m/s for the coolant velocity and 0.5 - 7.5 MW/m 2 for the heat flux (whose axial distribution is uniform). Forty-two thermocouples and eight pressure taps were placed at several axial locations, measuring wall temperature and pressure respectively. The analysis focused on turbulent flow with Reynolds numbers between 5.5 x 10 3 - 2.4 x 10 5 and Prandtl numbers between 1.5 - 6. It was shown that standard correlations as the Dittus-Boelter and Seider-Tate significantly under-estimate the heat transfer coefficient, especially at high Reynolds number. Other correlations specifically designed for narrow rectangular channels were also taken into account and compared. The correlation of Popov-Petukhov in the form suggested by Siman-Tov still under-estimates the heat transfer coefficient, even if slight improvements could be seen. A better agreement for the tests with gap equal to 2.16 mm could be found with the correlation of Ma and the one of Liang. However the heat transfer coefficient when the gap is equal to 1.51 mm could not be predicted accurately. Furthermore these correlations were based on data at low Reynolds numbers (up to 13000) and low heat flux, so the use of them for SULTAN-JHR may be questionable. According to the authors’ knowledge, existing models of heat transfer
Single phase and two phase erosion corrosion in broilers of gas-cooled reactors
International Nuclear Information System (INIS)
Harrison, G.S.; Fountain, M.J.
1988-01-01
Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 μg/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss
DEFF Research Database (Denmark)
Sera, Dezso; Kerekes, Tamas; Lungeanu, Marian
2005-01-01
The performances of the P+Resonant controller in case of current control for a single phase grid connected inverter have been proved to be superior to the PI controller, since it is able to remove the phase error of the control at the fundamental frequency of the grid. It offers also the possibil......The performances of the P+Resonant controller in case of current control for a single phase grid connected inverter have been proved to be superior to the PI controller, since it is able to remove the phase error of the control at the fundamental frequency of the grid. It offers also...... of the P+Resonant controller with selective harmonic compensation on a low-cost fixed-point DSP. The resonant part of the P+R has been implemented as a second order filter based on Delta operator. The current controller, together with harmonic compensation for the 3rd, 5th, and 7th harmonics has been...
Cascaded impedance networks for NPC inverter
DEFF Research Database (Denmark)
Li, Ding; Gao, Feng; Loh, Poh Chiang
2010-01-01
Multilevel inverters are getting more and more attracted because they have better output waveform quality and lower semiconductor voltage stress. The Z-source NPC is a kind of single stage multilevel inverter which has the ability of voltage boost. But the boost capability is relatively low when...... they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...... would have a higher output voltage gain. It is anticipated that it would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested. Experimental testing has already been conducted and verifies the theory....
Integrated Inverter For Driving Multiple Electric Machines
Su, Gui-Jia [Knoxville, TN; Hsu, John S [Oak Ridge, TN
2006-04-04
An electric machine drive (50) has a plurality of inverters (50a, 50b) for controlling respective electric machines (57, 62), which may include a three-phase main traction machine (57) and two-phase accessory machines (62) in a hybrid or electric vehicle. The drive (50) has a common control section (53, 54) for controlling the plurality of inverters (50a, 50b) with only one microelectronic processor (54) for controlling the plurality of inverters (50a, 50b), only one gate driver circuit (53) for controlling conduction of semiconductor switches (S1-S10) in the plurality of inverters (50a, 50b), and also includes a common dc bus (70), a common dc bus filtering capacitor (C1) and a common dc bus voltage sensor (67). The electric machines (57, 62) may be synchronous machines, induction machines, or PM machines and may be operated in a motoring mode or a generating mode.
Improvements in ANIS and inverted sputter sources
Strasters, B. A.; Vermeer, A.; van Zwol, N. A.
1984-02-01
In this article two sputter sources, i.e. an ANIS and an inverted sputter source are described. The ANIS has been changed into a SNICS-like configuration and measurements of the output current for different sputter target geometries are presented. In the inverted sputter source an immersion lens was placed between the ionizer and the sputter target. This source is provided with a modified revolving target head with eight targets.
Inverted mesiodens--a case report.
Nikhil, S; Vineeta; Gupta, P
1999-09-01
A nine and a half years old female school child was examined in a during routine dental examination. The patient had swelling over maxillary midline area just near the labial frenum. Both the central incisors were in position. Radiographic examination revealed presence of an inverted supernumerary tooth between the roots of the central incisors. Surgical extraction of the supernumerary was planned. A unique case of inverted (upside down) mesiodens is presented.
Automatic load sharing in inverter modules
Nagano, S.
1979-01-01
Active feedback loads transistor equally with little power loss. Circuit is suitable for balancing modular inverters in spacecraft, computer power supplies, solar-electric power generators, and electric vehicles. Current-balancing circuit senses differences between collector current for power transistor and average value of load currents for all power transistors. Principle is effective not only in fixed duty-cycle inverters but also in converters operating at variable duty cycles.
Base drive for paralleled inverter systems
Nagano, S. (Inventor)
1980-01-01
In a paralleled inverter system, a positive feedback current derived from the total current from all of the modules of the inverter system is applied to the base drive of each of the power transistors of all modules, thereby to provide all modules protection against open or short circuit faults occurring in any of the modules, and force equal current sharing among the modules during turn on of the power transistors.
A High-Power-Density Single-Phase Rectifier Based on Three-Level Neutral-Point Clamped Circuits
Directory of Open Access Journals (Sweden)
Tao Zhou
2017-05-01
Full Text Available A single-phase three-level converter is suitable for medium-power applications, with an interface voltage that is higher than that of a traditional two-level configuration. The three-level neutral-point clamped converter is adopted using four switches in each bridge arm, which, compared to a two-level rectifier, leads to less voltage stress, a lower switching frequency, and switching loss on switches. The transient current control strategy is designed to control the active power. The single-phase space vector pulse width modulation (SVPWM with a voltage balance strategy is designed to solve the neutral point voltage fluctuation problem and keep the dc-link voltage stable. A 1.3 kW high-power-density prototype based on SiC MOSFET was built and tested. The experimental results verified the high performance of steady-state and dynamic responses.
Directory of Open Access Journals (Sweden)
Gérald Franz
2013-11-01
Full Text Available An advanced elastic-plastic self-consistent polycrystalline model, accounting for intragranular microstructure development and evolution, is coupled with a bifurcation-based localization criterion and applied to the numerical investigation of the impact of microstructural patterns on ductility of single-phase steels. The proposed multiscale model, taking into account essential microstructural aspects, such as initial and induced textures, dislocation densities, and softening mechanisms, allows us to emphasize the relationship between intragranular microstructure of B.C.C. steels and their ductility. A qualitative study in terms of forming limit diagrams for various dislocation networks, during monotonic loading tests, is conducted in order to analyze the impact of intragranular substructure parameters on the formability of single-phase B.C.C. steels.
International Nuclear Information System (INIS)
Lemonnier, H.; Hervieu, E.
1991-01-01
Phase separation in a tee-junction is modelled in the particular case of bubbly-flow. The model is based on a two-dimensional approach and hence, uses local equations. The first step consists in modelling the single-phase flow in the tee-junction. The free streamline theory is used to predict the flow of the continuous phase. The two recirculation zones which are presented in this case are predicted by the model. The second step consists in predicting the gas bubble paths as a result of the actions of the single-phase flow. Finally, the trajectories of gas bubbles are used to predict the separation characteristics of the tee-junction. Each step of the modelling procedure has been carefully tested by an in-depth experimental investigation. Excellent quantitative agreement is obtained between experimental results and model predictions. Moreover, the phase separation phenomenon is found to be clearly described by the model. (orig.)
Vadgama, Rajeshkumar N; Odaneth, Annamma A; Lali, Arvind M
2015-12-01
Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.
Directory of Open Access Journals (Sweden)
Rajeshkumar N. Vadgama
2015-12-01
Full Text Available Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15 in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Abusorrah, Abdullah
2017-01-01
The quadrature signal generation based phase-locked loops (QSG-PLLs) are highly popular for synchronization purposes in single-phase systems. The main difference among these PLLs often lies in the technique they use for creating the fictitious quadrature component. One of the easiest QSG approaches...... is delaying the original single-phase signal by a quarter of a cycle. The PLL with such QSG technique is often called the transfer delay based PLL (TD-PLL). The TD-PLL benefits from a simple structure, rather fast dynamic response, and a good detection accuracy when the grid frequency is at its nominal value......, but it suffers from a phase offset error and double frequency oscillatory error in the estimated phase and frequency in the presence of frequency drifts. In this paper, a simple yet effective approach to remove the aforementioned errors of the TD-PLL is proposed. The resultant PLL structure is called...
Directory of Open Access Journals (Sweden)
Menxi Xie
2017-06-01
Full Text Available High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL uses a multiplier as phase detector(PD. As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF applied in-loop of pPLL. The signal characteristic of phase error is dissussed in detail. A predictive rule is adopted to compensate the delay induced by MAF, thus achieving fast dynamic response. In the case of frequency deviate from nomimal, estimated frequency is fed back to adjust the filter window length of MAF and buffer size of predictive rule. Simulation and experimental results show that proposed PLL achieves good performance under adverse grid conditions.
Energy Technology Data Exchange (ETDEWEB)
Ljusev, P.; Andersen, Michael A.E.
2005-07-01
This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach it is not required to do any measurements, thus making it more reliable. Initial testing made on the prototype prove the feasibility of the approach. (au)
DEFF Research Database (Denmark)
Lico, Pasqualino; Marinelli, Mattia; Knezovic, Katarina
2015-01-01
In Denmark, household consumers are supplied with three phase with neutral cable. In addition, the distribution service operator cannot decide to which phase electrical appliance are connected. The technician who realizes the installation connects the loads according to his technical expertise...... stations are equipped with single-phase converters. According to the designed control strategy, the charging spot can select the phase to be used for the charge. The selection is done according to a phase voltage measurement....
A single-phase PWM controlled AC to DC converter based on control of unity displacement power factor
Funabiki, Shigeyuki
1990-01-01
A modified pulse-width modulation (PWM) technique that improves the displacement power factor and the input power factor of a single-phase AC to DC converter is discussed. The modified converter is shown to have a high input power factor and allows the of DC voltage from zero to more than the maximum value of the source voltage. The displacement power factor is unity, and the input power factor is almost unity in the wide range of current command
Jeong-Man Kim; Jang-Young Choi; Kyu-Seok Lee; Sung-Ho Lee
2017-01-01
This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE) systems. In order to implement the design of linear oscillatory generator (LOG) for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the effi...
Vinokurova, T. Yu.; Dobryagina, O. A.; Shagurina, E. S.; Shuin, V. A.
2015-01-01
Protections based by higher harmonics absolute measurements the zero sequence currents of the protected object connections against single-phase earth faults in resonant grounded cable networks of medium voltage industrial and urban energy supply systems have been widely applied in Russia since the late 60s of the 20th century. However, some operational problems connected with sufficient selectivity and sensitivity of these protection devices appeared with time. Sensitivity and selectivity of ...
DEFF Research Database (Denmark)
Senturk, O.S.; Hava, A.M.
2011-01-01
This paper proposes the waveform reconstruction method (WRM), which is utilized in the single-phase series active filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...
Marrone, Salvatore; Colagrossi, Andrea; Di Mascio, Andrea; Le Touzé, David
2016-05-01
The study of energetic free-surface flows is challenging because of the large range of interface scales involved due to multiple fragmentations and reconnections of the air-water interface with the formation of drops and bubbles. Because of their complexity the investigation of such phenomena through numerical simulation largely increased during recent years. Actually, in the last decades different numerical models have been developed to study these flows, especially in the context of particle methods. In the latter a single-phase approximation is usually adopted to reduce the computational costs and the model complexity. While it is well known that the role of air largely affects the local flow evolution, it is still not clear whether this single-phase approximation is able to predict global flow features like the evolution of the global mechanical energy dissipation. The present work is dedicated to this topic through the study of a selected problem simulated with both single-phase and two-phase models. It is shown that, interestingly, even though flow evolutions are different, energy evolutions can be similar when including or not the presence of air. This is remarkable since, in the problem considered, with the two-phase model about half of the energy is lost in the air phase while in the one-phase model the energy is mainly dissipated by cavity collapses.
Inverter for Installations with Intermittent Electricity Production
Directory of Open Access Journals (Sweden)
Ermuraki Iu.
2016-04-01
Full Text Available A new architecture of the inverter used in the convertion of electric energy generated by renewable energy sources is studied in this paper. The distinctive features of this inverter is the special block which compensates pulsing of the current with double frequency, characteristic for these inverters. The switching of electronic keys is realized using the method TCM In this block, like in the inverter, which assures the switching at the voltages near to zero (ZVC. The proposed algorithm of controlling the electronic keys permits to increase the work frequency up to hundreds of kHz. Electronic keys operate at variable frequency, which changes during the work cycle both slowly and by jump. The assurance of admissible heat regime is performed using forced cooling air flux and by convection. The increase of releasing process of the heat is assured by original construction of radiators which forms the turbulent mode of cooling air flux. These changes of the architecture of the inverter have allowed the minimization of mass, sizes and price indicators. It has been manufactured a functional laboratory sample with output power of 2kW the voltage of direct current of 450V or 48 V and output alternating voltage of 230V, with sizes 175mmX35mmX30mm.
Addressable inverter matrix for process and device characterization
Buehler, M. G.; Sayah, H. R.
1985-01-01
The addressable inverter matrix consists of 222 inverters each accessible with the aid of a shift register. The structure has proven useful in characterizing the variability of inverter transfer curves and in diagnosing processing faults. For good 3-micron CMOS bulk inverters investigated, the percent standard deviation of the inverter threshold voltage was less than one percent and the inverter gain (the slope of the inverter transfer curve at the inverter threshold vltage) was less than 3 percent. The average noise margin for the inverters was near 2 volts for a power supply voltage of 5 volts. The specific faults studied included undersize pull-down transistor widths and various open contacts in the matrix.
Power inverter implementing phase skipping control
Somani, Utsav; Amirahmadi, Ahmadreza; Jourdan, Charles; Batarseh, Issa
2016-10-18
A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control inputs of the first, second and third phase circuitry, where the drivers are configured for receiving phase skipping control signals from the controller and outputting mode selection signals configured to dynamically select an operating mode for the DC/AC inverter from a Normal Control operation and a Phase Skipping Control operation which have different power injection patterns through the first, second and third phase circuitry depending upon the power level.
Radiological follow-up of inverted papilloma
Energy Technology Data Exchange (ETDEWEB)
Petit, P.; Vivarrat-Perrin, L.; Champsaur, P.; Juhan, V.; Chagnaud, C.; Vidal, V.; Gaubert, J.Y.; Bartoli, J.M.; Moulin, G. [Department of Radiology, Groupe Hospitalier de la Timone, Centre Hospitalier et Universitaire de Marseille, F-13385 Marseille Cedex 5 (France); Dessi, P.; Zanaret, M. [Department of Head and Neck Surgery, Groupe Hospitalier de la Timone, Centre Hospitalier et Universitaire de Marseille, F-13385 Marseille Cedex 5 (France)
2000-07-01
The aim of this study was to describe cross-sectional imaging features of recurrent papilloma of the nasal fossa and paranasal sinuses and to evaluate the role of MR and CT in the postoperative follow-up of this lesion. Magnetic resonance imaging and CT of ten patients who presented recurrence of inverted papilloma were reviewed and correlated to initial imaging, endoscopy, and surgical reports. Imaging patterns of recurrent inverted papilloma are identical to those of initial tumors and recurrence location is closely related to the site of the former lesion. Magnetic resonance is more efficient than CT for the diagnosis and evaluation of extensions. Magnetic resonance supplies the deficiencies of endoscopy in case of extensions to the frontal sinus or the lateral recess of the antrum, especially if mucosal hyperplasia or sinusitis is associated. Magnetic resonance imaging is the first imaging modality to perform in the follow-up after removal of inverted papilloma. (orig.)
An SCR inverter for electric vehicles
Latos, T.; Bosack, D.; Ehrlich, R.; Jahns, T.; Mezera, J.; Thimmesch, D.
1980-01-01
An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated topology. This paper describes the major role the controller plays in generating the motor excitation voltage and frequency to deliver performance similar to dc systems. Motoring efficiency test data for the controller are presented. It is concluded that an SCR inverter in conjunction with an ac induction motor is a viable alternative to present dc vehicle propulsion systems on the basis of performance and size criteria.
International Nuclear Information System (INIS)
Basu, Dipankar N.; Bhattacharyya, Souvik; Das, P.K.
2014-01-01
Highlights: • Comprehensive review of state-of-the-art on single-phase natural circulation loops. • Detailed discussion on growth in solar thermal system and nuclear thermal hydraulics. • Systematic development in scaling methodologies for fabrication of test facilities. • Importance of numerical modeling schemes for stability assessment using 1-D codes. • Appraisal of current trend of research and possible future directions. - Abstract: A comprehensive review of single-phase natural circulation loop (NCL) is presented here. Relevant literature reported since the later part of 1980s has been meticulously surveyed, with occasional obligatory reference to a few pioneering studies originating prior to that period, summarizing the key observations and the present trend of research. Development in the concept of buoyancy-induced flow is discussed, with introduction to flow initiation in an NCL due to instability. Detailed discussion on modern advancement in important application areas like solar thermal systems and nuclear thermal hydraulics are presented, with separate analysis for various reactor designs working on natural circulation. Identification of scaling criteria for designing lab-scale experimental facilities has gone through a series of modification. A systematic analysis of the same is presented, considering the state-of-the-art knowledge base. Different approaches have been followed for modeling single-phase NCLs, including simplified Lorenz system mostly for toroidal loops, 1-D computational modeling for both steady-state and stability characterization and 3-D commercial system codes to have a better flow visualization. Methodical review of the relevant studies is presented following a systematic approach, to assess the gradual progression in understanding of the practical system. Brief appraisal of current research interest is reported, including the use of nanofluids for fluid property augmentation, marine reactors subjected to rolling waves
Synthesis and reactivity of single-phase Be{sub 17}Ti{sub 2} intermetallic compounds
Energy Technology Data Exchange (ETDEWEB)
Kim, Jae-Hwan, E-mail: kim.jaehwan@jaea.go.jp [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan); Iwakiri, Hirotomo; Furugen, Tatsuaki [Faculty of Education Elementary and Secondary School Teacher Training Program, University of the Ryukyus, Okinawa (Japan); Nakamichi, Masaru [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan)
2016-01-15
Highlights: • Preliminary synthesis of single-phase Be{sub 17}Ti{sub 2} was succeeded. • Reactivity difference between beryllium and beryllides may be caused by a lattice strain. • Oxidation of Be{sub 17}Ti{sub 2} at high temperatures results in the formation of TiO{sub 2}. • Simulation results reveal that a stable site for hydrogen at the center of tetrahedron exists. - Abstract: To investigate feasibility for application of Be{sub 17}Ti{sub 2} as a neutron multiplier as well as a refractory material, single-phase Be{sub 17}Ti{sub 2} intermetallic compounds were synthesized using an annealing heat treatment of the starting powder and a plasma sintering method. Scanning electron microscopic observations and X-ray diffraction measurements reveal that the single-phase Be{sub 17}Ti{sub 2} compounds were successfully synthesized. We examined the reactivity of Be{sub 17}Ti{sub 2} with 1% H{sub 2}O and discovered that a larger stoichiometric amount of Ti resulted in the formation of TiO{sub 2} on the surface at high temperatures. This oxidation may also contribute to an increase in both weight gain and generation of H{sub 2}. This suggests that the formation of the Ti-depleted Be{sub 17}Ti{sub 2−x} layer as a result of oxidation facilitates an increased reactivity with H{sub 2}O. To evaluate the safety aspects of Be{sub 17}Ti{sub 2}, we also investigated the hydrogen positions and solution energies based on the first principle. The calculations reveal that there are 10 theoretical sites, where 9 of these sites have hydrogen solution energies with a positive value (endothermic) and 1 site located at the center of a tetrahedron comprising two Be and two Ti atoms gives a negative value (exothermic).
Smart Inverters for Utility and Industry Applications
DEFF Research Database (Denmark)
Xue, Yaosuo; Guerrero, Josep M.
2015-01-01
Smart inverters are emerging with increasing renewable energy and smart grid development. While the recent work reviewed mostly focuses on defining standardized control functionalities and smart grid communication protocols, we take a holistic approach in this paper and propose a holon-type smart...... inverter concept, which features autonomous, adaptive, cooperative and plug-and-play functions. Self-awareness is also continually driven by power electronics inherently. These features can be favorable in a complex environment with more and more small-scale power electronics-based devices, and can reduce...
Asymmetrical transformer-based embedded Z-source inverters
DEFF Research Database (Denmark)
Wei, Mo; Loh, Poh Chiang; Blaabjerg, Frede
2013-01-01
Z-source inverters are inverters with buck-boost capability that traditional inverters cannot match. Despite this ability, present Z-source topologies are burdened by some limitations such as chopping input current, high-voltage stress and poor spectral performance at high gain. To improve...... their performances, a number of asymmetrical transformer-based embedded Z-source inverters are proposed. Through theoretical derivation and experiments, the proposed inverters have been shown to draw a smooth input current and produce a high gain by varying the transformer turns ratio n. The range of variation for n...... depends on the inverter topology chosen, which in turn depends on the application under consideration....
Characteristics Comparison of High-Frequency Multi-Level Inverter Connected with Filter Inverters
Iwaya, Kazuki; Noguchi, Toshihiko
This paper presents characteristics comparison of a high-frequency multi-level inverter connected with small capacity filter inverters. In general, PWM inverters require a low-pass filter in order to reduce switching harmonics. However, in the high-frequency systems such as class D power amplifiers, the cut-off frequency of the low-pass filter must set at high frequency. Thus, harmonic distortion of the output voltage harmfully enlarges. Increasing the number of output voltage levels is effective to reduce the harmonic distortion of the output voltage and the low-pass filter size. The proposed systems consist of a 5-level inverter and several cascade-connected low-voltage full bridge inverters without any external DC power sources for filtering the output voltage. The 5-level inverter generates a stepwise waveform with 5-level voltage, and the low voltage filter inverter superimposes harmonic components to compensate for the voltage waveform distortion. Therefore, the proposed system can reduce its total switching loss and can increase the number of the output voltage levels. In this paper, effectiveness of the proposed systems is verified through several experiments.
Directory of Open Access Journals (Sweden)
Jeong-Man Kim
2017-05-01
Full Text Available This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE systems. In order to implement the design of linear oscillatory generator (LOG for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.
A modified P&O MPPT algorithm for single-phase PV systems based on deadbeat control
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2012-01-01
A modified perturb and observe (P&O) algorithm is presented to improve maximum power point tracking (MPPT) performance of photovoltaic (PV) systems. This modified algorithm is applied to a single-phase PV system based on deadbeat control in order to test the tracking accuracy and its impact...... on the reliability of the whole system. Both simulations and experimental results show that the proposed algorithm offers a fast response as well as smaller steady-state oscillations even under low irradiance condition compared with classical methods....
DEFF Research Database (Denmark)
Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.
2015-01-01
This paper presents an analysis and comparison of boundary conduction mode (BCM) and continuous conduction mode (CCM) in single phase power factor correction (PFC) applications. The comparison is based on double pulse tester (DPT) characterization results of state-of-the-art superjunction devices...... in the 600V range. The measured switching energy is used to evaluate the devices performance in a conventional PFC. This data is used together with a mathematical model for prediction of the conducted electromagnetic interference (EMI). This allows comparing the different devices in BCM and CCM operation...... modes and evaluating the performance as a function of the PFC power density and efficiency....
Dorao, C. A.; Drewes, S.; Fernandino, M.
2018-02-01
During the past few decades, heat transfer during convective flow boiling inside pipes has been widely studied with the goal of unveiling the physics of the process. Different heat transfer mechanisms have been suggested based on different assumptions. This fact has resulted in a large number of models including different dimensionless numbers and in some cases up to a dozen of adjusted parameters. Here, we show that the convective flow boiling heat transfer coefficient is equivalent to the one for single-phase flow when the influence of the vapour velocity is taken into account.
Schwarz, Florian; Hinkel, Rabea; Baloch, Elisabeth; Marcus, Roy P; Hildebrandt, Kristof; Sandner, Torleif A; Kupatt, Christian; Hoffmann, Verena; Wintersperger, Bernd J; Reiser, Maximilian F; Theisen, Daniel; Nikolaou, Konstantin; Bamberg, Fabian
2013-12-01
This study sought to compare dynamic versus single-phase high-pitch computed tomography (CT) acquisitions for the assessment of myocardial perfusion in a porcine model with adjustable degrees of coronary stenosis. The incremental value of the 2 different approaches to CT-based myocardial perfusion imaging remains unclear. Country pigs received stent implantation in the left anterior descending coronary artery, in which an adjustable narrowing (50% and 75% stenoses) was created using a balloon catheter. All animals underwent CT-based rest and adenosine-stress myocardial perfusion imaging using dynamic and single-phase high-pitch acquisitions at both degrees of stenosis. Fluorescent microspheres served as a reference standard for myocardial blood flow. Segmental CT-based myocardial blood flow (MBFCT) was derived from dynamic acquisitions. Segmental single-phase enhancement (SPE) was recorded from high-pitch, single-phase examinations. MBFCT and SPE were compared between post-stenotic and reference segments, and receiver-operating characteristic curve analysis was performed. Among 6 animals (28 ± 2 kg), there were significant differences of MBFCT and SPE between post-stenotic and reference segments for all acquisitions at 75% stenosis. By contrast, although for 50% stenosis at rest, MBFCT was lower in post-stenotic than in reference segments (0.65 ± 0.10 ml/g/min vs. 0.75 ± 0.16 ml/g/min, p < 0.05), there was no difference for SPE (128 ± 27 Hounsfield units vs. 137 ± 35 Hounsfield units, p = 0.17), which also did not significantly change under adenosine stress. In receiver-operating characteristic curve analyses, segmental MBFCT showed significantly better performance for ischemia prediction at 75% stenosis and stress (area under the curve: 0.99 vs. 0.89, p < 0.05) as well as for 50% stenosis, regardless of adenosine administration (area under the curve: 0.74 vs. 0.57 and 0.88 vs. 0.61, respectively, both p < 0.05). At higher degrees of coronary stenosis, both
A simple and consistent equation of state for sodium in the single phase and two phase regions
International Nuclear Information System (INIS)
Breton, J.P.
1976-01-01
An equation of state valid over an extended temperature and density range has been derived. Then, the following properties have been deduced : coefficient of thermal expansion, isothermal coefficient of bulk compressibility, thermal pressure coefficient, heat capacity at constant pressure, at constant volume, along the saturation curve for liquid, for vapor, heat of vaporization, speed of sound, and finally the Mollier diagram and the entropy diagram. All the obtained properties are thermodynamically consistent and satisfy the basic relations of thermodynamics for both single phase and two-phase regions. Experimental results were always used when available. (auth.)
Kim, Jeong-Man; Choi, Jang-Young; Lee, Kyu-Seok; Lee, Sung-Ho
2017-05-01
This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE) systems. In order to implement the design of linear oscillatory generator (LOG) for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.
DEFF Research Database (Denmark)
Pahlevani, Majid; Eren, Suzan; Guerrero, Josep M.
2016-01-01
This paper presents a new active/reactive power closed-loop control system for a hybrid renewable energy generation system used for single-phase residential/commercial applications. The proposed active/reactive control method includes a hybrid estimator, which is able to quickly and accurately...... estimate the active/reactive power values. The proposed control system enables the hybrid renewable energy generation system to be able to perform real-time grid interconnection services such as active voltage regulation, active power control, and fault ride-through.Simulation and experimental results...... demonstrate the superior performance of the proposed closed-loop control system....
Directory of Open Access Journals (Sweden)
Predrag Pejovic
2013-12-01
Full Text Available Application of a single phase rectifier as an example in teaching circuit modeling, normalization, operating modes of nonlinear circuits, and circuit analysis methods is proposed.The rectifier supplied from a voltage source by an inductive impedance is analyzed in the discontinuous as well as in the continuous conduction mode. Completely analytical solution for the continuous conduction mode is derived. Appropriate numerical methods are proposed to obtain the circuit waveforms in both of the operating modes, and to compute the performance parameters. Source code of the program that performs such computation is provided.
DEFF Research Database (Denmark)
Rezkalla, Michel M.N.; Zecchino, Antonio; Martinenas, Sergejus
2017-01-01
solutions. The objective of this paper is twofold: first, it aims to implement and validate fast frequency control and synthetic (virtual) inertia control, employing single phase electric vehicles as flexibility resources. Second, it proposes a trade-off analysis between the two controllers......The increasing share of distributed and inertia-less resources entails an upsurge in balancing and system stabilisation services. In particular, the displacement of conventional generation reduces the available rotational inertia in the power system, leading to high interest in synthetic inertia...
Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction
Goto, Sho; Kura, Hiroaki; Watanabe, Eiji; Hayashi, Yasushi; Yanagihara, Hideto; Shimada, Yusuke; Mizuguchi, Masaki; Takanashi, Koki; Kita, Eiji
2017-01-01
Tetrataenite (L10-FeNi) is a promising candidate for use as a permanent magnet free of rare-earth elements because of its favorable properties. In this study, single-phase L10-FeNi powder with a high degree of order was synthesized through a new method, nitrogen insertion and topotactic extraction (NITE). In the method, FeNiN, which has the same ordered arrangement as L10-FeNi, is formed by nitriding A1-FeNi powder with ammonia gas. Subsequently, FeNiN is denitrided by topotactic reaction to ...
International Nuclear Information System (INIS)
Hooper, J.D.
1977-01-01
A combined experimental and numerical model of a turbulent single phase coolant, flowing axially along the fuel pins of a nuclear reactor, was developed. The experimental rig represented two interconnected subchannels of a square array at a pitch/diameter ratio of 1.193. Air was the working fluid, and measurements were made of the mean radial velocity profiles, wall shear stress variation, turbulence velocity spectra and intensities. The numerically predicted wall shear distribution and mean velocity profiles, obtained using an empirical two-dimensional mixing length and eddy diffusivity concept to represent fluid turbulence, showed good agreement with the experimental results. (Author)
Nimchuk, Zachary L; Perdue, Tony D
2017-01-01
Live imaging of above ground meristems can lead to new insights in plant development not possible from static imaging of fixed tissue. The use of an upright confocal microscope offers several technical and biological advantages for live imaging floral or shoot meristems. However, many departments and core facilities possess only inverted confocal microscopes and lack the funding for an additional upright confocal microscope. Here we show that imaging of living apical meristems can be performed on existing inverted confocal microscopes with the use of an affordable and detachable InverterScope accessory.
Biess, J. J.; Inouye, L. Y.; Shank, J. H.
1974-01-01
A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.
Directory of Open Access Journals (Sweden)
S.Z.Mohammad Noor
2016-06-01
Full Text Available This paper presents an implementation of Single-phase Single stage String inverter for Grid connected Photovoltaic (PV system. The proposed system uses Modified Perturb and Observe (P&O algorithm implemented using Fuzzy Logic Control (FLC as Maximum Power Point Tracking (MPPT. The inverter is designed for 340W system using two series of STP170s24/Ac PV modules. The MPPT unit keeps tracking the maximum power from the PV array by changing the modulation index and the phase angle of inverter’s output voltage. The simulation model is developed using Matlab/Simulink to evaluate the performance of the converter. Selected experimental results are also presented in this paper.
Piyarat, Wekin; Kinnares, Vijit
This paper presents a performance evaluation and a simple speed control method of an asymmetrical parameter type two-phase induction motor drive using a three-leg VSI (Voltage Source Inverter). The two-phase induction motor is adapted from an existing single-phase induction motor resulting in impedance unbalance between main and auxiliary windings. The unbalanced two-phase inverter outputs with orthogonal displacement based on a SPWM (Sinusoidal Pulse Width Modulation) method are controlled with appropriate amplitudes for improving the motor performance. Dynamic simulation of the proposed drive system is given. A simple speed controller based on a slip regulation method is designed. The overall system is implemented on a DSP (Digital Signal Processor) board. The validity of the proposed system is verified by simulation and experimental results.
DEFF Research Database (Denmark)
Hu, Junjie; Marinelli, Mattia; Coppo, Massimiliano
2016-01-01
phases. To address this problem, distribution transformers with single-phase tapping capability, together with reactive power provision of PV systems, are under investigation. This paper presents modeling and analysis of the benefits of coordinated voltage control of a decoupled three-phase on-load tap...... changer (OLTC) and photovoltaic inverters in a distribution system, for accommodating a greater number of photovoltaic generators in the grid. A 24 h root-mean-square simulation study is performed in the DigSilent PowerFactory with a 1 s time step using 10 min resolution consumption and production...... profiles on a real Danish distribution grid, as well as the developed dynamic photovoltaic generation and load models. The simulations show that the joint action of the power distribution transformer with OLTC control on each phase, and the reactive power provision of photovoltaic inverters, significantly...
Inverted Pedagogy in Second Semester Calculus
Kennedy, Ellie; Beaudrie, Brian; Ernst, Dana C.; St. Laurent, Roy
2015-01-01
This study investigates the effects of applying an inverted classroom model in a second-semester calculus course at a large regional university in the southwest during the Spring of 2013. The sample consisted of four class sections with the same instructor, with a total of 173 students; two class sections were in the experimental group, whereas…
Inverting the Transition-to-Proof Classroom
Talbert, Robert
2015-01-01
In this paper, we examine the benefits of employing an inverted or "flipped" class design in a Transition-to-Proof course for second-year mathematics majors. The issues concomitant with such courses, particularly student acquisition of "sociomathematical norms" and self-regulated learning strategies, are discussed along with…
The Internet and the Inverted Classroom.
Lage, Maureen J.; Platt, Glenn
2000-01-01
Describes a Web site that is for an undergraduate principles of microeconomics course and a main component of "The Inverted Classroom" in which lectures take place outside of class. Explains that the Web site is divided into four sections: (1) the classroom; (2) the desk; (3) the coffee shop; and (4) the library. (CMK)
Solar Power Station Output Inverter Control Design
Directory of Open Access Journals (Sweden)
J. Bauer
2011-04-01
Full Text Available The photovoltaic applications spreads in these days fast, therefore they also undergo great development. Because the amount of the energy obtained from the panel depends on the surrounding conditions, as intensity of the sun exposure or the temperature of the solar array, the converter must be connected to the panel output. The Solar system equipped with inverter can supply small loads like notebooks, mobile chargers etc. in the places where the supplying network is not present. Or the system can be used as a generator and it shall deliver energy to the supply network. Each type of the application has different requirements on the converter and its control algorithm. But for all of them the one thing is common – the maximal efficiency. The paper focuses on design and simulation of the low power inverter that acts as output part of the whole converter. In the paper the design of the control algorithm of the inverter for both types of inverter application – for islanding mode and for operation on the supply grid – is discussed. Attention is also paid to the design of the output filter that should reduce negative side effects of the converter on the supply network.
Subintegrality, invertible modules and Laurent polynomial extensions
Indian Academy of Sciences (India)
Indian Acad. Sci. (Math. Sci.) Vol. 125, No. 2, May 2015, pp. 149–160. c Indian Academy of Sciences. Subintegrality, invertible modules and Laurent polynomial extensions. VIVEK SADHU. Department of Mathematics ...... comments which have improved the exposition. Further, he would like to thank CSIR,. India for financial ...
Two-Stage Series-Resonant Inverter
Stuart, Thomas A.
1994-01-01
Two-stage inverter includes variable-frequency, voltage-regulating first stage and fixed-frequency second stage. Lightweight circuit provides regulated power and is invulnerable to output short circuits. Does not require large capacitor across ac bus, like parallel resonant designs. Particularly suitable for use in ac-power-distribution system of aircraft.
Inverter Matrix for the Clementine Mission
Buehler, M. G.; Blaes, B. R.; Tardio, G.; Soli, G. A.
1994-01-01
An inverter matrix test circuit was designed for the Clementine space mission and is built into the RRELAX (Radiation and Reliability Assurance Experiment). The objective is to develop a circuit that will allow the evaluation of the CMOS FETs using a lean data set in the noisy spacecraft environment.
Pulse width modulation inverter with battery charger
Slicker, James M. (Inventor)
1985-01-01
An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .theta., where .theta. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands for electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a flyback DC-DC converter circuit for recharging the battery.
The invertible double of elliptic operators
DEFF Research Database (Denmark)
Booss-Bavnbek, Bernhelm; Lesch, Matthias; Zhu, Chaofeng
We construct a canonical invertible double for general first order elliptic differential operators over smooth compact manifolds with boundary and derive a natural formula for the Calderon projector which yields a generalization of the famous Cobordism Theorem. Assuming symmetric principal symbol...
International Nuclear Information System (INIS)
Ishii, M.; Kataoka, I.
1983-03-01
Scaling criteria for a natural circulation loop under single phase and two-phase flow conditions have been derived. For a single phase case the continuity, integral momentum, and energy equations in one-dimensional area average forms have been used. From this, the geometrical similarity groups, friction number, Richardson number, characteristic time constant ratio, Biot number, and heat source number are obtained. The Biot number involves the heat transfer coefficient which may cause some difficulties in simulating the turbulent flow regime. For a two-phase flow case, the similarity groups obtained from a perturbation analysis based on the one-dimensional drift-flux model have been used. The physical significance of the phase change number, subcooling number, drift-flux number, friction number are discussed and conditions imposed by these groups are evaluated. In the two-phase flow case, the critical heat flux is one of the most important transients which should be simulated in a scale model. The above results are applied to the LOFT facility in case of a natural circulation simulation. Some preliminary conclusions on the feasibility of the facility have been obtained
Energy Technology Data Exchange (ETDEWEB)
Ishii, M.; Kataoka, I.
1983-03-01
Scaling criteria for a natural circulation loop under single phase and two-phase flow conditions have been derived. For a single phase case the continuity, integral momentum, and energy equations in one-dimensional area average forms have been used. From this, the geometrical similarity groups, friction number, Richardson number, characteristic time constant ratio, Biot number, and heat source number are obtained. The Biot number involves the heat transfer coefficient which may cause some difficulties in simulating the turbulent flow regime. For a two-phase flow case, the similarity groups obtained from a perturbation analysis based on the one-dimensional drift-flux model have been used. The physical significance of the phase change number, subcooling number, drift-flux number, friction number are discussed and conditions imposed by these groups are evaluated. In the two-phase flow case, the critical heat flux is one of the most important transients which should be simulated in a scale model. The above results are applied to the LOFT facility in case of a natural circulation simulation. Some preliminary conclusions on the feasibility of the facility have been obtained.
International Nuclear Information System (INIS)
Ribando, R.J.
1979-01-01
A comparison is made between computed results and experimental data for a single-phase natural convection test in an experimental sodium loop. The test was conducted in the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility, an engineering-scale high temperature sodium loop at the Oak Ridge National Laboratory (ORNL) used for thermal-hydraulic testing of simulated Liquid Metal Fast Breeder Reactor (LMFBR) subassemblies at normal and off-normal operating conditions. Heat generation in the 19 pin assembly during the test was typical of decay heat levels. The test chosen for analysis in this paper was one of seven natural convection runs conducted in the facility using a variety of initial conditions and testing parameters. Specifically, in this test the bypass line was open to simulate a parallel heated assembly and the test was begun with a pump coastdown from a small initial forced flow. The computer program used to analyze the test, LONAC (LOw flow and NAtural Convection) is an ORNL-developed, fast-running, one-dimensional, single-phase, finite-difference model used for simulating forced and free convection transients in the THORS loop
International Nuclear Information System (INIS)
Faiz, Jawad; Kasebi, F.; Pillay, P.
2004-01-01
This paper addresses a problem that occurs in many small appliances. As such, it is an important problem of energy utilization. To improve the performance of a single phase capacitor start/run induction motor, FET type power transistors could be used to replace a SCR H bridge. Such a configuration can lead to a simpler and more inexpensive circuit for the electronically controlled capacitor. In this paper, ICs and an OP-AMP are used to design an electronically controlled capacitor for a single phase induction motor. The design can compensate for the input voltage fluctuations that are present in the normal operation of the motor. In addition, an improvement in its performance can be obtained. At present, the use of a tachometer can be considered a disadvantage of the proposed scheme. Thus, a configuration that enables removal of the tachometer, while maintaining reasonable cost, is desirable. In addition, replacing the ac capacitor with one rated for dc can lead to a system reduction, in addition to a considerable reduction in the size of the circuit due to the use of integrated circuits
Directory of Open Access Journals (Sweden)
Xianjin Huang
2017-11-01
Full Text Available In the application of vehicle power supply and distributed power generation, there are strict requirements for the pulse width modulation (PWM converter regarding power density and reliability. When compared with the conventional insulated gate bipolar transistor (IGBT module, the Reverse Conducting-Insulated Gate Bipolar Transistor (RC-IGBT with the same package has a lower thermal resistance and higher current tolerance. By applying the gate desaturation control, the reverse recovery loss of the RC-IGBT diode may be reduced. In this paper, a loss threshold desaturation control method is studied to improve the output characteristics of the single-phase PWM converter with a low switching frequency. The gate desaturation control characteristics of the RC-IGBT’s diode are studied. A proper current limit is set to avoid the ineffective infliction of the desaturation pulse, while the bridge arm current crosses zero. The expectation of optimized loss decrease is obtained, and the better performance for the RC-IGBTs of the single-phase PWM converter is achieved through the optimized desaturation pulse distribution. Finally, the improved predictive current control algorithm that is applied to the PWM converter with RC-IGBTs is simulated, and is operated and tested on the scaled reduced power platform. The results prove that the gate desaturation control with the improved predictive current algorithm may effectively improve the RC-IGBT’s characteristics, and realize the stable output of the PWM converter.
The Application Three-phase to Single-phase Z-Source Matrix Converter in Wind Turbine
Directory of Open Access Journals (Sweden)
vahid asadi rad
2017-01-01
Full Text Available In this paper a new idea of direct three-phase to single-phase Z-source matrix converter (impedance-source matrix converter applicable in stand-alone wind turbine is introduced. In the direct Z-source matrix converter amplitude of output voltage and frequency regulation are of importance to control system. In wind turbines, input voltage and frequency are usually changing due to wind speed variation that these alterations could be easily regulated by means of a direct Z-source matrix converter. A scheme is also offered to control the proposed direct three-phase to single-phase Z-source matrix converter. the control strategy would be able to adjust the output voltage and frequency at desired value as well as producing low THD (total harmonic distortion at the output voltage. The proposed structure and the control methodology are simulated using matlab simulink software and results are investigated and discussed to confirm the performance of the direct Z-source matrix converter in wind turbine.
Directory of Open Access Journals (Sweden)
Yeongsu Bak
2015-04-01
Full Text Available This paper presents an indirect matrix converter (IMC topology for hybrid electric vehicle (HEV application with three-phase and single-phase outputs. The HEV includes mechanical, electrical, control, and electrochemical systems among others. In the mechanical system, a traction motor and a compressor motor are used to drive the HEV. The traction motor and the compressor motor are usually operated as three-phase and single-phase motors, respectively. In this respect, a dual AC-drive system can operate the traction and the compressor motor simultaneously. Furthermore, compared to a conventional dual matrix converter system, the proposed topology can reduce the number of switches that the dual outputs share with a DC-link. The application of this system for HEV has advantages, like long lifetime and reduced volume due to the lack of a DC-link. The proposed control strategy and modulation schemes ensure the sinusoidal input and output waveforms and bidirectional power transmission. The proposed system for the HEV application is verified by simulation and experiments.
Energy Technology Data Exchange (ETDEWEB)
Ribando, R.J.
1979-01-01
A comparison is made between computed results and experimental data for a single-phase natural convection test in an experimental sodium loop. The test was conducted in the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility, an engineering-scale high temperature sodium loop at the Oak Ridge National Laboratory (ORNL) used for thermal-hydraulic testing of simulated Liquid Metal Fast Breeder Reactor (LMFBR) subassemblies at normal and off-normal operating conditions. Heat generation in the 19 pin assembly during the test was typical of decay heat levels. The test chosen for analysis in this paper was one of seven natural convection runs conducted in the facility using a variety of initial conditions and testing parameters. Specifically, in this test the bypass line was open to simulate a parallel heated assembly and the test was begun with a pump coastdown from a small initial forced flow. The computer program used to analyze the test, LONAC (LOw flow and NAtural Convection) is an ORNL-developed, fast-running, one-dimensional, single-phase, finite-difference model used for simulating forced and free convection transients in the THORS loop.
Energy Technology Data Exchange (ETDEWEB)
Berry, R. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2017-08-14
In the literature, the abundance of pipe network junction models, as well as inclusion of dissipative losses between connected pipes with loss coefficients, has been treated using the incompressible flow assumption of constant density. This approach is fundamentally, physically wrong for compressible flow with density change. This report introduces a mathematical modeling approach for general junctions in piping network systems for which the transient flows are compressible and single-phase. The junction could be as simple as a 1-pipe input and 1-pipe output with differing pipe cross-sectional areas for which a dissipative loss is necessary, or it could include an active component, between an inlet pipe and an outlet pipe, such as a pump or turbine. In this report, discussion will be limited to the former. A more general branching junction connecting an arbitrary number of pipes with transient, 1-D compressible single-phase flows is also presented. These models will be developed in a manner consistent with the use of a general equation of state like, for example, the recent Spline-Based Table Look-up method [1] for incorporating the IAPWS-95 formulation [2] to give accurate and efficient calculations for properties for water and steam with RELAP-7 [3].
International Nuclear Information System (INIS)
Kiswanta; Edy Sumarno; Joko Prasetio W; Ainur Rosidi; G B Heru K
2013-01-01
Innovation design of BETA test loop has been done. BETA test loop is a research facility used as a support for experiments of reactor accident simulation. The innovation was performed to prepare experimental facilities in order to study flow of heat transfer in single-phase and two-phase flows. The design was executed by modifying new piping of UUB's primary system, addition of heat flux measurements and imaging thermal for easiness of experimental result analysis. UUB development and experiments were carried out to understand heat transfer process in the narrow gap of two-phase flow considering this phenomenon is one of the conditions postulated in PWR typed nuclear power plant accident scenario. The innovation design of BETA test loop is still in the planning stages so that the design has not been constructed. Piping systems made of SS-304 with the ability to use a maximum pressure of 10 bar with a diameter of % inch pipe to, from the calculation of minimal design that is 7.27 mm. If the tube SS-304 - ASTM B88 is the wall thickness of 0.083 inches. From this design it is indicated that the design is able to be fabricated and used for experimental study of heat transfer in single-phase and two-phase flows. (author)
Adam, Khaled; Zöllner, Dana; Field, David P.
2018-04-01
Modeling the microstructural evolution during recrystallization is a powerful tool for the profound understanding of alloy behavior and for use in optimizing engineering properties through annealing. In particular, the mechanical properties of metallic alloys are highly dependent upon evolved microstructure and texture from the softening process. In the present work, a Monte Carlo (MC) Potts model was used to model the primary recrystallization and grain growth in cold rolled single-phase Al alloy. The microstructural representation of two kinds of dislocation densities, statistically stored dislocations and geometrically necessary dislocations were quantified based on the ViscoPlastic Fast Fourier transform method. This representation was then introduced into the MC Potts model to identify the favorable sites for nucleation where orientation gradients and entanglements of dislocations are high. Additionally, in situ observations of non-isothermal microstructure evolution for single-phase aluminum alloy 1100 were made to validate the simulation. The influence of the texture inhomogeneity is analyzed from a theoretical point of view using an orientation distribution function for deformed and evolved texture.
Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction.
Goto, Sho; Kura, Hiroaki; Watanabe, Eiji; Hayashi, Yasushi; Yanagihara, Hideto; Shimada, Yusuke; Mizuguchi, Masaki; Takanashi, Koki; Kita, Eiji
2017-10-16
Tetrataenite (L1 0 -FeNi) is a promising candidate for use as a permanent magnet free of rare-earth elements because of its favorable properties. In this study, single-phase L1 0 -FeNi powder with a high degree of order was synthesized through a new method, nitrogen insertion and topotactic extraction (NITE). In the method, FeNiN, which has the same ordered arrangement as L1 0 -FeNi, is formed by nitriding A1-FeNi powder with ammonia gas. Subsequently, FeNiN is denitrided by topotactic reaction to derive single-phase L1 0 -FeNi with an order parameter of 0.71. The transformation of disordered-phase FeNi into the L1 0 phase increased the coercive force from 14.5 kA/m to 142 kA/m. The proposed method not only significantly accelerates the development of magnets using L1 0 -FeNi but also offers a new synthesis route to obtain ordered alloys in non-equilibrium states.
Sui, Yi; Zheng, Ping; Cheng, Luming; Wang, Weinan; Liu, Jiaqi
2017-05-01
A single-phase axially-magnetized permanent-magnet (PM) oscillating machine which can be integrated with a free-piston Stirling engine to generate electric power, is investigated for miniature aerospace power sources. Machine structure, operating principle and detent force characteristic are elaborately studied. With the sinusoidal speed characteristic of the mover considered, the proposed machine is designed by 2D finite-element analysis (FEA), and some main structural parameters such as air gap diameter, dimensions of PMs, pole pitches of both stator and mover, and the pole-pitch combinations, etc., are optimized to improve both the power density and force capability. Compared with the three-phase PM linear machines, the proposed single-phase machine features less PM use, simple control and low controller cost. The power density of the proposed machine is higher than that of the three-phase radially-magnetized PM linear machine, but lower than the three-phase axially-magnetized PM linear machine.
FPGA Based Compensation Method for Correcting Distortion in Voltage Inverters
National Research Council Canada - National Science Library
Williamson, Kenya D
2007-01-01
...) voltage source inverters. Blanking time distortion is caused by the delay inserted to prevent the short circuit that would occur if the two transistors in the same inverter leg are both on at the same time...
DEFF Research Database (Denmark)
Yang, Yongheng; Koutroulis, Eftichios; Sangwongwanich, Ariya
2015-01-01
Several countries with considerable PhotoVoltaic (PV) installations are facing a challenge of overloading the power infrastructure during peak-power production hours. Regulations have been imposed on the PV systems, where more active power control should be flexibly performed. As an advanced...... control strategy, the Absolute Active Power Control (AAPC) can effectively solve the overloading issues by limiting the maximum possible PV power to a certain level (i.e., the power limitation), and also benefit the inverter reliability. However, its feasibility is challenged by the energy loss....... An increase of the inverter lifetime and a reduction of the energy yield can alter the cost of energy, demanding an optimization of the power limitation. Therefore, aiming at minimizing the Levelized Cost of Energy (LCOE), the power limit is optimized for the AAPC strategy in this paper. The optimization...
Inverter Anti-Islanding with Advanced Grid Support in Single- and Multi-Inverter Islands
Energy Technology Data Exchange (ETDEWEB)
Hoke, Andy
2016-08-16
As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1. In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2. The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness.
Efficient/reliable dc-to-dc inverter circuit
Pasciutti, E. R.
1970-01-01
Feedback loop, which contains an inductor in series with a saturable reactor, is added to a standard inverter circuit to permit the inverter power transistors to be switched in a controlled and efficient manner. This inverter is applicable where the power source has either high or low impedance properties.
Do pregnant women know how to correct inverted nipples ...
African Journals Online (AJOL)
Inverted nipples occur in an estimated 9 to 10 percent of women globally, contributing to the number of women who are not exclusively breastfeeding their infants. Women with inverted nipples may want to breastfeed, but infants may be unable to latch to the breast. Inverted nipples can be corrected, but it is unclear if women ...
Pulsewidth-modulated 2-source neutral-point-clamped inverter
DEFF Research Database (Denmark)
Blaabjerg, Frede; Loh, Poh Chang; Gao, Feng
2007-01-01
This paper presents the careful integration of a newly proposed Z-source topological concept to the basic neutral-point-clamped (NPC) inverter topology for designing a three-level inverter with both voltage-buck and voltage-boost capabilities. The designed Z-source NPC inverter uses two unique X-...
Mobile Inverted Constructivism: Education of Interaction Technology in Social Media
Chai, Jia-Xiang; Fan, Kuo-Kuang
2016-01-01
The combination of social media and invert teaching is a new path to inverting interation technology education and reconstructing the curriculum of context. In this paper, based on the theory of constructivism learning, a model named Mobile Inverted Constructivism (MIC) is provided. Moreover, in view of the functional quality of social media in…
Power Inverter Topologies for Photovoltaic Modules - A Review
DEFF Research Database (Denmark)
Kjær, Søren Bækhøj; Pedersen, John Kim; Blaabjerg, Frede
2002-01-01
This review-paper focuses on the latest development of inverters for photovoltaic AC-Modules. The power range for these inverters is usually within 90 Watt to 500 Watt, which covers the most commercial photovoltaic-modules. Self-commutated inverters have replaced the grid-commutated ones. The same...
Diode-Assisted Buck-Boost Current Source Inverters
DEFF Research Database (Denmark)
Gao, F.; Cai, Liang; Loh, P.C.
2007-01-01
This paper presents a couple of novel current source inverters (CSIs) with the enhanced current buckboost capability. With the unique diode-inductor network added between current source inverter circuitry and current boost elements, the proposed buck-boost current source inverters demonstrate...
Online Variable Topology-Type Photovoltaic Grid-Connected Inverter
DEFF Research Database (Denmark)
Wu, Fengjiang; Sun, Bo; Duan, Jiandong
2015-01-01
and H-bridge inverter under the conditions of variable output voltage and power of the PV array. It is proved that, compared with the H-bridge inverter, the operation range of the cascaded inverter is wider, whereas the total loss is larger. Furthermore, a novel online variable topology-type grid...
DC-to-AC inverter ratio failure detector
Ebersole, T. J.; Andrews, R. E.
1975-01-01
Failure detection technique is based upon input-output ratios, which is independent of inverter loading. Since inverter has fixed relationship between V-in/V-out and I-in/I-out, failure detection criteria are based on this ratio, which is simply inverter transformer turns ratio, K, equal to primary turns divided by secondary turns.
Energy Technology Data Exchange (ETDEWEB)
Clavier, R., E-mail: remi.clavier@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) – PSN-RES/SEREX/LE2M, Cadarache bât. 327, 13115 St Paul-lez-Durance (France); Chikhi, N., E-mail: nourdine.chikhi@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) – PSN-RES/SEREX/LE2M, Cadarache bât. 327, 13115 St Paul-lez-Durance (France); Fichot, F. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) – PSN-RES/SAG/LEPC, Cadarache bât. 700, 13115 St Paul-lez-Durance (France); Quintard, M. [Université de Toulouse – INPT – UPS – Institut de Mécanique des Fluides de Toulouse (IMFT), Allée Camille Soula, F-31400 Toulouse (France); CNRS – IMFT, F-31400 Toulouse (France)
2015-10-15
Highlights: • Single-phase pressure drops versus flow rates in particle beds are measured. • Conditions are representative of the reflooding of a nuclear fuel debris bed. • Darcy, weak inertial, strong inertial and weak turbulent regimes are observed. • A Darcy–Forchheimer law is found to be a good approximation in this domain. • A predictive correlation is derived from new experimental data. - Abstract: During a severe nuclear power plant accident, the degradation of the reactor core can lead to the formation of debris beds. The main accident management procedure consists in injecting water inside the reactor vessel. Nevertheless, large uncertainties remain regarding the coolability of such debris beds. Motivated by the reduction of these uncertainties, experiments have been conducted on the CALIDE facility in order to investigate single-phase pressure losses in representative debris beds. In this paper, these results are presented and analyzed in order to identify a simple single-phase flow pressure loss correlation for debris-bed-like particle beds in reflooding conditions, which cover Darcean to Weakly Turbulent flow regimes. The first part of this work is dedicated to study macro-scale pressure losses generated by debris-bed-like particle beds, i.e., high sphericity (>80%) particle beds with relatively small size dispersion (from 1 mm to 10 mm). A Darcy–Forchheimer law, involving the sum of a linear term and a quadratic deviation, with respect to filtration velocity, has been found to be relevant to describe this behavior in Darcy, Strong Inertial and Weak Turbulent regimes. It has also been observed that, in a restricted domain (Re = 15 to Re = 30) between Darcy and Weak Inertial regimes, deviation is better described by a cubic term, which corresponds to the so-called Weak Inertial regime. The second part of this work aims at identifying expressions for coefficients of linear and quadratic terms in Darcy–Forchheimer law, in order to obtain a
Stochastic p-Bits for Invertible Logic
Directory of Open Access Journals (Sweden)
Kerem Yunus Camsari
2017-07-01
Full Text Available Conventional semiconductor-based logic and nanomagnet-based memory devices are built out of stable, deterministic units such as standard metal-oxide semiconductor transistors, or nanomagnets with energy barriers in excess of ≈40–60 kT. In this paper, we show that unstable, stochastic units, which we call “p-bits,” can be interconnected to create robust correlations that implement precise Boolean functions with impressive accuracy, comparable to standard digital circuits. At the same time, they are invertible, a unique property that is absent in standard digital circuits. When operated in the direct mode, the input is clamped, and the network provides the correct output. In the inverted mode, the output is clamped, and the network fluctuates among all possible inputs that are consistent with that output. First, we present a detailed implementation of an invertible gate to bring out the key role of a single three-terminal transistorlike building block to enable the construction of correlated p-bit networks. The results for this specific, CMOS-assisted nanomagnet-based hardware implementation agree well with those from a universal model for p-bits, showing that p-bits need not be magnet based: any three-terminal tunable random bit generator should be suitable. We present a general algorithm for designing a Boltzmann machine (BM with a symmetric connection matrix [J] (J_{ij}=J_{ji} that implements a given truth table with p-bits. The [J] matrices are relatively sparse with a few unique weights for convenient hardware implementation. We then show how BM full adders can be interconnected in a partially directed manner (J_{ij}≠J_{ji} to implement large logic operations such as 32-bit binary addition. Hundreds of stochastic p-bits get precisely correlated such that the correct answer out of 2^{33} (≈8×10^{9} possibilities can be extracted by looking at the statistical mode or majority vote of a number of time samples. With perfect
Stochastic p -Bits for Invertible Logic
Camsari, Kerem Yunus; Faria, Rafatul; Sutton, Brian M.; Datta, Supriyo
2017-07-01
Conventional semiconductor-based logic and nanomagnet-based memory devices are built out of stable, deterministic units such as standard metal-oxide semiconductor transistors, or nanomagnets with energy barriers in excess of ≈40 - 60 kT . In this paper, we show that unstable, stochastic units, which we call "p -bits," can be interconnected to create robust correlations that implement precise Boolean functions with impressive accuracy, comparable to standard digital circuits. At the same time, they are invertible, a unique property that is absent in standard digital circuits. When operated in the direct mode, the input is clamped, and the network provides the correct output. In the inverted mode, the output is clamped, and the network fluctuates among all possible inputs that are consistent with that output. First, we present a detailed implementation of an invertible gate to bring out the key role of a single three-terminal transistorlike building block to enable the construction of correlated p -bit networks. The results for this specific, CMOS-assisted nanomagnet-based hardware implementation agree well with those from a universal model for p -bits, showing that p -bits need not be magnet based: any three-terminal tunable random bit generator should be suitable. We present a general algorithm for designing a Boltzmann machine (BM) with a symmetric connection matrix [J ] (Ji j=Jj i) that implements a given truth table with p -bits. The [J ] matrices are relatively sparse with a few unique weights for convenient hardware implementation. We then show how BM full adders can be interconnected in a partially directed manner (Ji j≠Jj i) to implement large logic operations such as 32-bit binary addition. Hundreds of stochastic p -bits get precisely correlated such that the correct answer out of 233 (≈8 ×1 09) possibilities can be extracted by looking at the statistical mode or majority vote of a number of time samples. With perfect directivity (Jj i=0 ) a small
DEFF Research Database (Denmark)
Bhaskar, Mahajan Sagar; Padmanaban, Sanjeevikumar; Fedák, Viliam
2017-01-01
supplies or capacitor banks. To design the proposed five level inverter five numbers of power control switches and eight diodes are required. The proposed inverter circuitry is investigated by using Non-Inverting Double Reference Single Carrier PWM (NIDRSC PWM) Technique in terms of harmonics content...
DEFF Research Database (Denmark)
Lu, Yong; Xiao, Guochun; Wang, Xiongfei
2016-01-01
The unified power quality conditioner (UPQC) is known as an effective compensation device to improve PQ for sensitive end-users. This paper investigates the operation and control of a single-phase three-leg UPQC (TL-UPQC), where a novel space vector modulation method is proposed for naturally...... solving the coupling problem introduced by the common switching leg. The modulation method is similar to the well-known space vector modulation widely used with three-phase voltage source converters, which thus brings extra flexibility to the TL-UPQC system. Two optimized modulation modes with either...... reduced switching loss or harmonic distortion are derived, evaluated, and discussed, in order to demonstrate the flexibility brought by the space vector modulated TL-UPQC. Simulations and experimental results are presented to verify the feasibility and effectiveness of the proposed space vector modulation...
A residual-based a posteriori error estimator for single-phase Darcy flow in fractured porous media
Chen, Huangxin
2016-12-09
In this paper we develop an a posteriori error estimator for a mixed finite element method for single-phase Darcy flow in a two-dimensional fractured porous media. The discrete fracture model is applied to model the fractures by one-dimensional fractures in a two-dimensional domain. We consider Raviart–Thomas mixed finite element method for the approximation of the coupled Darcy flows in the fractures and the surrounding porous media. We derive a robust residual-based a posteriori error estimator for the problem with non-intersecting fractures. The reliability and efficiency of the a posteriori error estimator are established for the error measured in an energy norm. Numerical results verifying the robustness of the proposed a posteriori error estimator are given. Moreover, our numerical results indicate that the a posteriori error estimator also works well for the problem with intersecting fractures.
DEFF Research Database (Denmark)
Kejian, Song; Konstantinou, Georgios; Jing, Li
2017-01-01
multiple unit traction system is proposed in this study. The strategy is based on a multiple frequency tuned quasi-proportional resonant controller in the ac-side current loop and a multiple frequency tuned notch filter in the dc-link voltage loop. Under the typical supply voltage distortion present......Operational data from Chinese railways indicate a number of challenges for traction four-quadrant converter (4QC) control including low-order voltage and current harmonics and reference tracking. A control strategy for a single-phase three-level neutral-point-clamped 4QC employed in the electric...... in the network, the proposed control strategy improves the current tracking performance and reduces the line current harmonics, when compared with conventional control strategies. Experimental results, both under purely sinusoidal and distorted supply voltages, validate the effectiveness of the proposed control...
Liquid Hole-Multipliers: A potential concept for large single-phase noble-liquid TPCs of rare events
Breskin, Amos
2013-10-01
A novel concept is proposed for large-volume single-phase noble-liquid TPC detectors for rare events. Both radiation-induced scintillation-light and ionization-charge are detected by Liquid Hole-Multipliers (LHM), immersed in the noble liquid. The latter may consist of cascaded Gas Electron Multipliers (GEM), Thick Gas Electron Multiplier (THGEM) electrodes or others, coated with CsI UV-photocathodes. Electrons, photo-induced on CsI by primary scintillation in the noble liquid, and event-correlated drifting ionization electrons are amplified in the cascaded elements primarily through electroluminescence, and possibly through additional moderate avalanche, occurring within the holes. The resulting charge-signals or light-pulses are recorded on anode pads or with photosensors - e.g. gaseous photomultipliers (GPM), respectively. Potential affordable solutions are proposed for multi-ton dark-matter detectors; open questions are formulated for validating this dream.
Liquid Hole-Multipliers: A potential concept for large single-phase noble-liquid TPCs of rare events
International Nuclear Information System (INIS)
Breskin, Amos
2013-01-01
A novel concept is proposed for large-volume single-phase noble-liquid TPC detectors for rare events. Both radiation-induced scintillation-light and ionization-charge are detected by Liquid Hole-Multipliers (LHM), immersed in the noble liquid. The latter may consist of cascaded Gas Electron Multipliers (GEM), Thick Gas Electron Multiplier (THGEM) electrodes or others, coated with CsI UV-photocathodes. Electrons, photo-induced on CsI by primary scintillation in the noble liquid, and event-correlated drifting ionization electrons are amplified in the cascaded elements primarily through electroluminescence, and possibly through additional moderate avalanche, occurring within the holes. The resulting charge-signals or light-pulses are recorded on anode pads or with photosensors – e.g. gaseous photomultipliers (GPM), respectively. Potential affordable solutions are proposed for multi-ton dark-matter detectors; open questions are formulated for validating this dream
DEFF Research Database (Denmark)
Golestan, Saeed; Monfared, Mohammad; D. Freijedo, Francisco
2012-01-01
they present. Typically, the single-phase PLLs use a sinusoidal multiplier as the phase detector (PD). These PLLs are generally referred to as the power-based PLL (pPLL). In this paper, the drawbacks associated with the pPLL technique (i.e., the sensitivity to the grid voltage variations, and the double...... frequency oscillations which appear in the estimated phase/frequency) are discussed in detail, and some of the previously reported solutions are examined. Then, to overcome these drawbacks, a simple and effective technique, called the double-frequency and amplitude compensation (DFAC) method is proposed....... The effectiveness of the proposed method is evaluated through a detailed mathematical analysis. A systematic design method to fine-tune the PLL parameters is then suggested, which guarantees a fast transient response, a high disturbance rejection capability, and a robust performance. Finally, the simulation...
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
The increasing number of renewable energy sources at the distribution grid is becoming a major issue for utility companies, since the grid connected converters are operating at different operating points due to the probabilistic characteristics of renewable energy. Besides, typically, the harmonics...... proposes a new model of a single phase grid connected renewable energy source using the Harmonic State Space modeling approach, which is able to identify such problems and the model can be extended to be applied in the multiple connected converter analysis. The modeling results show the different harmonic...... and impedance from other renewable energy sources are not taken carefully into account in the installation and design. However, this may bring an unknown harmonic instability into the multiple power sourced system and also make the analysis difficult due to the complexity of the grid network. This paper...
Energy Technology Data Exchange (ETDEWEB)
Onar, Omer C [ORNL; Tang, Lixin [ORNL; Chinthavali, Madhu Sudhan [ORNL; Campbell, Steven L [ORNL; Miller (JNJ), John M. [JNJ-Miller PLC
2014-01-01
Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.
International Nuclear Information System (INIS)
Du Sijia; Zhang Hong; Jia Baoshan
2011-01-01
Experiments have been conducted to study the heat transfer characteristics of single-phase forced circulation when the test tube was under different marine conditions. The experiments measured the wall temperature of test tube to calculate the heat transfer coefficients at different circumferential places. When the test tube was under inclined conditions, the heat transfer coefficient increased at downside and decreased at upside of test tube because of buoyancy effect. When the test tube was under rolling conditions, the heat transfer coefficients fluctuated with the rolling motions, and the Coriolis force dominated the heat transfer fluctuation during the rolling motion. CFD method was used to simulate the heat transfer phenomena under marine conditions, and the results were accord to the experimental phenomena. (authors)
Directory of Open Access Journals (Sweden)
N. Pour Mahmoud
2017-10-01
Full Text Available This paper attempts to study flows within fractures through a set of numerical simulations. In addition, a special care is given to hydraulic features and characteristics of fractures. The research is performed through the application of calculative fluid dynamics and a finite volume discrete schema. The investigated flows are laminar, single-phase and stable flows of water and air through fractures with penetrable walls. The selected fracture geometry is inspired from the tomographic scan of a stone fracture. Water and air are modeled in fractures with permeable walls and different permeability levels. It has been observed that in case of permeable matrixes, the friction coefficient is lower compared to impermeable matrixes. In fact permeability reduced friction. In addition, highest pressure drops were observed in areas with smaller fracture diaphragms. Nonetheless, the surrounding area of the fracture is analyzed with the consideration of Darcy's rule.
International Nuclear Information System (INIS)
Lee, S.H.; Mudawar, I.; Hasan, Mohammad M.
2016-01-01
Highlights: • Hybrid Thermal Control System (H-TCS) is proposed for future spacecraft. • Thermodynamic performance of H-TCS is examined for different space missions. • Operational modes including single-phase, two-phase and heat pump are explored. • R134a is deemed most appropriate working fluid. - Abstract: An urgent need presently exists to develop a new class of versatile spacecraft capable of conducting different types of missions and enduring varying gravitational and temperature environments, including Lunar, Martian and Near Earth Object (NEOs). This study concerns the spacecraft's Thermal Control System (TCS), which tackles heat acquisition, especially from crew and avionics, heat transport, and ultimate heat rejection by radiation. The primary goal of the study is to explore the design and thermal performance of a Hybrid Thermal Control System (H-TCS) that would satisfy the diverse thermal requirements of the different space missions. The H-TCS must endure both ‘cold’ and ‘hot’ environments, reduce weight and size, and enhance thermodynamic performance. Four different operational modes are considered: single-phase, two-phase, basic heat pump and heat pump with liquid-side, suction-side heat exchanger. A thermodynamic trade study is conducted for six different working fluids to assess important performance parameters including mass flow rate of the working fluid, maximum pressure, radiator area, compressor/pump work, and coefficient of performance (COP). R134a is determined to be most suitable based on its ability to provide a balanced compromise between reducing flow rate and maintaining low system pressure, and a moderate coefficient of performance (COP); this fluid is also both nontoxic and nonflammable, and features zero ozone depletion potential (ODP) and low global warming potential (GWP). It is shown how specific mission stages dictate which mode of operation is most suitable, and this information is used to size the radiator for
Bischoff, Bernhard; Deseive, Simon; Rampp, Martin; Todica, Andrei; Wermke, Marc; Martinoff, Stefan; Massberg, Steffen; Reiser, Maximilian F; Becker, Hans-Christoph; Hausleiter, Jörg
2017-04-01
Coronary CT angiography (CCTA) suffers from a reduced diagnostic accuracy in patients with heavily calcified coronary arteries or prior myocardial revascularisation due to artefacts caused by calcifications and stent material. CT myocardial perfusion imaging (CTMPI) yields high potential for the detection of myocardial ischemia and might help to overcome the above mentioned limitations. We analysed CT single-phase perfusion using high-pitch helical image acquisition technique in patients with prior myocardial revascularisation. Thirty-six patients with an indication for invasive coronary angiography (28 with coronary stents, 2 with coronary artery bypass grafts and 6 with both) were included in this prospective study at two study sites. All patients were examined on a 2nd generation dual-source CT system. Stress CT images were obtained using a prospectively ECG-triggered single-phase high-pitch helical image acquisition technique. During stress the tracer for myocardial perfusion (MP) SPECT imaging was administered. Rest CT images were acquired using prospectively ECG-triggered sequential CT. MP-SPECT imaging and invasive coronary angiography served as standard of reference. In this heavily diseased patient cohort CCTA alone showed a low overall diagnostic accuracy for detection of hemodynamically relevant coronary artery stenosis of only 31% on a per-patient base and 60% on a per-vessel base. Combining CCTA and CTMPI allowed for a significantly higher overall diagnostic accuracy of 78% on a per-patient base and 92% on a per-vessel base (p CT scans was 0.9 mSv, mean radiation dose for rest CT scans was 5.0 mSv. In symptomatic patients with known coronary artery disease and prior myocardial revascularization combining CCTA and CTMPI showed significantly higher diagnostic accuracy in detection of hemodynamically significant coronary artery stenosis when compared to CCTA alone.