95 results on '"Abdelsalam, Ibrahim"'
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2. Nanotechnology as a tool for abiotic stress mitigation in horticultural crops
- Author
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Abdelsalam, Ibrahim M., Ghosh, Soumya, AlKafaas, Samar Sami, Bedair, Heba, Malloum, Alhadji, ElKafas, Sara Samy, and Saad-Allah, Khalil M.
- Published
- 2023
- Full Text
- View/download PDF
3. Potential implementation of trees to remediate contaminated soil in Egypt
- Author
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Bedair, Heba, Ghosh, Soumya, Abdelsalam, Ibrahim M., Keerio, Ayaz Ali, and AlKafaas, Samar Sami
- Published
- 2022
- Full Text
- View/download PDF
4. Five-level F-type inverter with buck-boost converter-based equalization channels
- Author
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Elserougi, Ahmed A., Abdelsalam, Ibrahim, and Massoud, Ahmed
- Published
- 2023
- Full Text
- View/download PDF
5. Standalone PV-based single-phase split-source inverter using model-predictive control
- Author
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Elthokaby, Youssuf, Abdelsalam, Ibrahim, Abdel-Rahim, Naser, and Mohamed, Islam
- Published
- 2023
- Full Text
- View/download PDF
6. An Assessment of Net Metering and Feed-in Tariffs for Grid-Connected PV Systems in the Kuwaiti Market
- Author
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Alajmi, Bader N., Ahmed, Nabil A., Abdelsalam, Ibrahim, and Marei, Mostafa I.
- Published
- 2022
- Full Text
- View/download PDF
7. Ultralow Catalytic Loading for Optimised Electrocatalytic Performance of AuPt Nanoparticles to Produce Hydrogen and Ammonia.
- Author
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Bezerra, Leticia S., Brasseur, Paul, Sullivan‐Allsop, Sam, Cai, Rongsheng, da Silva, Kaline N., Wang, Shiqi, Singh, Harishchandra, Yadav, Ashok K., Santos, Hugo L. S., Chundak, Mykhailo, Abdelsalam, Ibrahim, Heczko, Vilma J., Sitta, Elton, Ritala, Mikko, Huo, Wenyi, Slater, Thomas J. A., Haigh, Sarah J., and Camargo, Pedro H. C.
- Subjects
GREEN fuels ,CLEAN energy ,NANOPARTICLES ,SURFACE segregation ,DENSITY functional theory ,NITRITES ,AMMONIA ,HOT carriers - Abstract
The hydrogen evolution and nitrite reduction reactions are key to producing green hydrogen and ammonia. Antenna–reactor nanoparticles hold promise to improve the performances of these transformations under visible‐light excitation, by combining plasmonic and catalytic materials. However, current materials involve compromising either on the catalytic activity or the plasmonic enhancement and also lack control of reaction selectivity. Here, we demonstrate that ultralow loadings and non‐uniform surface segregation of the catalytic component optimize catalytic activity and selectivity under visible‐light irradiation. Taking Pt−Au as an example we find that fine‐tuning the Pt content produces a 6‐fold increase in the hydrogen evolution compared to commercial Pt/C as well as a 6.5‐fold increase in the nitrite reduction and a 2.5‐fold increase in the selectivity for producing ammonia under visible light excitation relative to dark conditions. Density functional theory suggests that the catalytic reactions are accelerated by the intimate contact between nanoscale Pt‐rich and Au‐rich regions at the surface, which facilitates the formation of electron‐rich hot‐carrier puddles associated with the Pt‐based active sites. The results provide exciting opportunities to design new materials with improved photocatalytic performance for sustainable energy applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Simplified three‐phase split‐source inverter for PV system application controlled via model‐predictive control.
- Author
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Elthokaby, Youssuf, Abdelsalam, Ibrahim, Abdel‐Rahim, Naser, and Mohamed, Islam
- Subjects
- *
PHOTOVOLTAIC power systems , *DC-to-DC converters , *ELECTRIC power distribution grids , *CAPACITOR banks - Abstract
Summary: In this paper, for standalone and grid‐connected PV systems, a three‐phase simplified split‐source inverter (SSI) is proposed and controlled using a model‐predictive control (MPC). The maximum power point tracking (MPPT) approach used is an incremental conductance method based on a PI controller for both systems. The standalone system is composed of PV modules, a three‐phase SSI, and a bidirectional power DC–DC converter that connects a battery bank and a DC‐side capacitor. The output AC voltages of SSI are controlled using MPC. The bidirectional power DC–DC converter regulates the DC‐link voltage (DCLV). The grid‐connected system consists of PV modules, a three‐phase SSI, and an AC‐side L‐filter. The DC‐link PI controller generates reference currents for the MPC algorithm. The MPC uses these reference currents to adjust and deliver the PV power to the grid while regulating the DCLV. The PI controllers' parameters are selected for both systems using the Harris Hawks optimization method. Both PV systems simulation results show that under various operating conditions, they have succeeded in fixing a DCLV and producing a high‐quality AC output voltage and current at low THD. Experimental results for the three‐phase standalone PV system used to verify the system's performance. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Discrimination between normal and cancer white blood cells using holographic projection technique
- Author
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Rania M. Abdelazeem and Dahi Ghareab Abdelsalam Ibrahim
- Subjects
Medicine ,Science - Abstract
White blood cells (WBCs) play a vital role in the diagnosis of many blood diseases. Such diagnosis is based on the morphological analysis of blood microscopic images which is performed manually by skilled hematologist. However, this method has many drawbacks, such as the dependence on the hematologist’s skill, slow performance, and varying accuracy. Therefore, in the current study, a new optical method for discrimination between normal and cancer WBCs of peripheral blood film (PBF) images is presented. This method is based on holographic projection technique which is able to provide an accurate and fast optical reconstruction method of WBCs floating in the air. Besides, it can provide a 3D visualization map of one WBC with its characterization parameters from only a single 2D hologram. To achieve that, at first, WBCs are accurately segmented from the microscopic PBF images using a developed in-house MATLAB code. Then, their associated phase computer-generated holograms (CGHs) are calculated using the well-known iterative Fourier transform algorithm (IFTA). Within the utilized algorithm, a speckle noise reduction technique, based on temporal multiplexing of spatial frequencies, is applied to minimize the speckle noise across the reconstruction plane. Additionally, a special hologram modulation is added to the calculated holograms to provide a 3D visualization map of one WBC, and discriminate normal and cancer WBCs. Finally, the calculated phase-holograms are uploaded on a phase-only spatial light modulator (SLM) for optical reconstruction. The optical reconstruction of such phase-holograms yields precise representation of normal and cancer WBCs. Moreover, a 3D visualization map of one WBC with its characterization parameters is provided. Therefore, the proposed technique can be used as a valuable tool for interpretation and analysis of WBCs, this in turn could provide an improvement in diagnosis and prognosis of blood diseases.
- Published
- 2022
10. A bidirectional non-isolated hybrid modular DC–DC converter with zero-voltage switching
- Author
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Elserougi, Ahmed, Abdelsalam, Ibrahim, Massoud, Ahmed, and Ahmed, Shehab
- Published
- 2019
- Full Text
- View/download PDF
11. Rough surface characterization using off-axis digital holographic microscopy compensated with self-hologram rotation
- Author
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Abdelsalam Ibrahim, Dahi Ghareab
- Published
- 2018
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12. Controlled transition bridge converter: Operating principle, control and application in HVDC transmission systems
- Author
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Adam, G.P., Alsokhiry, Fahad, Abdelsalam, Ibrahim, Ahmed, Khaled H., and Al-Turki, Yusuf
- Published
- 2018
- Full Text
- View/download PDF
13. A hybrid bridgeless AC‐DC converter topology.
- Author
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Zakaria, Ahmed, Abdelsalam, Ibrahim, Marei, Mostafa I., and Mashaly, Hussein M.
- Subjects
- *
DC-to-DC converters , *TOPOLOGY , *SUPPLY & demand , *NEW business enterprises - Abstract
Summary: Bridgeless ac‐dc converters are the optimal choice for many applications, as they offer many advantages such as low distorted supply current, high power factor, and improved efficiency. This paper presents a new topology for a single‐phase bridgeless ac‐dc converter. The proposed hybrid topology is based on integrating the inverting and non‐inverting buck‐boost dc‐dc converters that are connected to the ac supply through an LC filter. To insure sinusoidal supply current, the proposed hybrid bridgeless ac‐dc converter is operated in discontinuous current mode. The proposed converter has many merits, such as a reduced number of components, enhanced efficiency, and soft start‐up capability. The operation modes and design of the proposed converter are presented. In addition, a design method is proposed for the input LC filter to minimize the voltage stress across switches. Moreover, a small signal model for the proposed converter is developed. The proposed converter topology is simulated to evaluate the dynamic behavior and verify the accuracy of the presented small signal model. Furthermore, an 850 W prototype is developed to validate the features of the proposed converter experimentally. Tight voltage regulation, sinusoidal supply current, and near‐to‐unity power factor operation are observed from the results, regardless of supply or load disturbances. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
14. A hybrid half‐bridge submodule‐based DC–DC modular multilevel converter with a single bidirectional high‐voltage valve.
- Author
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Elserougi, Ahmed, Abdelsalam, Ibrahim, and Massoud, Ahmed
- Subjects
- *
VALVES , *POWER electronics , *CAPACITORS - Abstract
Modular Multilevel Converters (MMCs) are promising candidates for high‐voltage high‐power applications. The main challenge of the MMCs is the zero‐frequency operation. To achieve a successful DC–DC conversion process with balanced capacitors' voltages with limited voltage ripple, this paper suggests the employment of the conventional two‐leg half‐bridge submodule‐based MMC structure in conjunction with a single bidirectional high‐voltage (HV) valve across the low‐voltage side. In the suggested structure, the HV valve is controlled on and off to ensure energy equalization for the MMC arms. In addition, soft‐switching for the HV valve is proposed to reduce the switching losses. Detailed illustration and design of the proposed concept are presented. Simulation and experimentation results are elucidated to show the effectiveness of the proposed DC–DC hybrid MMC. The results showed efficient performance of the suggested converter. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
15. Multi‐objective Optimization of Optimal Placement and Sizing of Distributed Generators in Distribution Networks.
- Author
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Alajmi, Bader N., AlHajri, M. F., Ahmed, Nabil A., Abdelsalam, Ibrahim, and Marei, Mostafa I.
- Subjects
PARTICLE swarm optimization ,ELECTRIC power systems ,GENETIC algorithms - Abstract
Due to the growing attention for the environmental impacts and power loss minimization, distributed generators (DGs) have been introduced widely into the electric power system. One of the challenges of integrating with the power system is to determine their optimal placement and sizing, which, when not respected, adversely affects the performance of the electrical network. In this paper, three multi‐objective algorithms of particle swarm optimization (PSO), variable constants (VCPSO) and genetic algorithm (GA) are adopted and implemented. The main objectives are to detect the optimum size and location of multiple DGs aiming to reduce the active power loss and improve bus voltage deviations in the distribution networks. The paper conducts a comprehensive review of the optimal size and location of the DG via systematic procedures, including definition, classifications, technologies of DGs. Then, the performances evaluation of the three optimization methods are presented and compared with other methods. The presented optimization methods are tested on the IEEE‐33 bus, 32‐line radial distribution network. Four different scenario‐based studies including base case and different number of DGs are performed to examine the accuracy of the presented algorithms. The obtained results prove that all the three algorithms are suitable for this multi‐objective optimization and VCPSO offers the best solution in terms of convergence and, and it has lowest average computation time. The performance and accuracy of the presented approaches and their improvements in the power loss and bus voltage profile are discussed and presented in detail. The obtained results show that more than 65% of active power loss reduction has been attained with the proper sizing and placement of DG systems. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
16. Discrimination between normal and cancer white blood cells using holographic projection technique.
- Author
-
Abdelazeem, Rania M. and Ghareab Abdelsalam Ibrahim, Dahi
- Subjects
- *
LEUCOCYTES , *SPECKLE interference , *MICROSCOPY , *SPATIAL light modulators , *HOLOGRAPHY - Abstract
White blood cells (WBCs) play a vital role in the diagnosis of many blood diseases. Such diagnosis is based on the morphological analysis of blood microscopic images which is performed manually by skilled hematologist. However, this method has many drawbacks, such as the dependence on the hematologist's skill, slow performance, and varying accuracy. Therefore, in the current study, a new optical method for discrimination between normal and cancer WBCs of peripheral blood film (PBF) images is presented. This method is based on holographic projection technique which is able to provide an accurate and fast optical reconstruction method of WBCs floating in the air. Besides, it can provide a 3D visualization map of one WBC with its characterization parameters from only a single 2D hologram. To achieve that, at first, WBCs are accurately segmented from the microscopic PBF images using a developed in-house MATLAB code. Then, their associated phase computer-generated holograms (CGHs) are calculated using the well-known iterative Fourier transform algorithm (IFTA). Within the utilized algorithm, a speckle noise reduction technique, based on temporal multiplexing of spatial frequencies, is applied to minimize the speckle noise across the reconstruction plane. Additionally, a special hologram modulation is added to the calculated holograms to provide a 3D visualization map of one WBC, and discriminate normal and cancer WBCs. Finally, the calculated phase-holograms are uploaded on a phase-only spatial light modulator (SLM) for optical reconstruction. The optical reconstruction of such phase-holograms yields precise representation of normal and cancer WBCs. Moreover, a 3D visualization map of one WBC with its characterization parameters is provided. Therefore, the proposed technique can be used as a valuable tool for interpretation and analysis of WBCs, this in turn could provide an improvement in diagnosis and prognosis of blood diseases. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
17. Copper oxide nanostructures as a potential method for control of zucchini yellow mosaic virus in squash.
- Author
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Derbalah, Aly, Abdelsalam, Ibrahim, Behiry, Said I., Abdelkhalek, Ahmed, Abdelfatah, Mahmoud, Ismail, Sherin, and Elsharkawy, Mohsen Mohamed
- Subjects
COPPER oxide ,MOSAIC viruses ,ZUCCHINI ,PHYTOPLASMAS ,SQUASHES - Abstract
BACKGROUND: Zucchini yellow mosaic virus (ZYMV) infects cucurbits and has been identified as a major limiting factor in their production. The purpose of this study was to create copper oxide nanostructures (CONS) to control ZYMV in squash plants. Protection of squash against ZYMV was assessed in terms of virus severity, ZYMV concentration, transcription of pathogenesis‐related genes and growth enhancement of treated squash. RESULTS: The findings revealed that squash plants treated with CONS had a significant reduction in disease severity when compared with untreated plants. In squash plants treated with CONS, defense genes associated with the salicylic acid signaling pathway were strongly expressed compared with untreated plants. The structural characteristics of CONS, such as their small size and appropriate shape, added to their excellent anti‐ZYMV efficacy. CONS‐treated squash plants show significantly improved growth traits compared with untreated plants. CONCLUSION: Based on the results of this study, CONS may be a new strategy for the control of ZYMV in squash. This represents an unconventional solution to control this virus, particularly as no chemical pesticides can control viral diseases. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
18. Generalized Active Power Flow Controller for Multiactive Bridge DC–DC Converters With Minimum-Current-Point-Tracking Algorithm.
- Author
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Hebala, Osama M., Aboushady, Ahmed A., Ahmed, Khaled H., and Abdelsalam, Ibrahim
- Subjects
ELECTRICAL load ,DC-to-DC converters ,REACTIVE power ,ALGORITHMS ,MAXIMUM power point trackers ,BRIDGE circuits ,VOLTAGE control - Abstract
This article proposes a new active power flow controller for dc–dc multiactive bridge (MAB) converters with minimum current point tracking (MCPT) to minimize conductive losses. Unlike recent efforts in this area, the proposed controller does not require look-up table for implementation nor complex nonlinear converter modeling and is not circuit parameter dependent. The proposed control scheme is also generalized for MAB converters with any number of ports and is derived in per unit form to enable standard implementation for buck/boost/unity-gain operating modes. The proposed MCPT algorithm is based on an innovative adaptive perturb and observe tracking of the minimum current point (MCP) on the MAB converter current characteristic plane. This MCP is tracked while active power regulation is simultaneously achieved based on a new phase shift decoupler to enable direct regulation of individual port active power. Detailed design procedure of the proposed controller is presented and extensive simulation is carried out to validate the effectiveness of the proposed MCPT closed loop controller. Experimental implementation is also provided to substantiate the simulation results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
19. An isolated‐boost‐converter‐based unidirectional three‐phase off‐board fast charger for electric vehicles.
- Author
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Elserougi, Ahmed, Abdelsalam, Ibrahim, and Massoud, Ahmed
- Subjects
- *
ELECTRIC vehicles , *BATTERY chargers , *ELECTRIC vehicle batteries , *ELECTRIC current converters , *DC-to-DC converters - Abstract
In this work, a novel three‐phase unidirectional off‐board Electric Vehicles (EVs) fast charger is proposed. Each phase of the proposed converter consists of a two‐stage converter. The first stage is an AC–DC front‐end converter with power factor correction (PFC) control. The front‐end AC–DC converter is based on an isolated boost converter, which has a boosting capability and provides galvanic isolation. In this stage, parallel‐in parallel‐out isolated boost converter modules are employed in each phase. This enables sharing the current among modules to avoid implementing one module with a high current rating to meet the fast‐charging requirements. The multimodule option provides fault‐ride through capability for the proposed charger. The DC outputs of involved phases, that is, three isolated DC voltages, are fed to three cascaded DC–DC unidirectional buck converters. The charging terminals are used to charge the EV battery through a filter inductor with a charging current controller's aid. A detailed illustration of the suggested closed‐loop controllers is presented to ensure a successful operation for the proposed architecture. A simulation case study for a 25‐kW charger is presented. Finally, a 1‐kW prototype is implemented for experimental validation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
20. Advanced Maximum Power Point Tracker for PV Systems Under Dusty Weather Environments.
- Author
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Ahmed, Nabil A., Alajmi, Bader N., Abdelsalam, Ibrahim, Marei, Mostafa I., and AlHajri, MF
- Subjects
PHOTOVOLTAIC power systems ,MAXIMUM power point trackers ,WEATHER ,SOLAR radiation - Abstract
Dusty weather is a most important disturbance for photovoltaic (PV) systems, that may result in PV panels exposure to partial shading conditions where the PV panel characteristics show several maximum power points. Moreover, dusty weather conditions may lead to rapid changes in solar radiations. Thus, conventional power system tracking algorithms are not being capable to track the global maximum power point (GMPP). This paper provides an advanced maximum power point tracker for partial shading and dusty weather conditions. In the presented technique, scanning and power lock conditions are added to the conventional perturbations and observation technique in photovoltaic system under partial shading or dusty weather conditions. This tracking method scans the PV characteristic in steps and stores all the maximum power points in order to get the GMPP. The proposed tracker is capable to identify the uniform weather conditions to save it from having unnecessary scanning. In addition, this tracker permits dynamic tracking of the GMPP under dusty weather conditions with less fluctuations and stable operation compared to the conventional methods. Accurate and fast conversion to the GMPP during various weather conditions is accomplished using the proposed technique. The proposed modified perturb and observe technique is validated using simulation and practical results. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
21. Modular Multilevel Converter With Self-Energy Equalization for Medium Voltage AC Drive Applications.
- Author
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Elserougi, Ahmed A., Abdelsalam, Ibrahim, Massoud, Ahmed, and Ahmed, Shehab
- Subjects
- *
VOLTAGE , *SEMICONDUCTOR devices , *AC DC transformers , *PASSIVE components , *ENERGY consumption , *CAPACITORS - Abstract
The modular multilevel converter (MMC) is a promising candidate for high-/medium-voltage high-power applications such as medium voltage ac drives due to its modularity, reliability, and scalability. The main challenge of a conventional MMC is low-frequency operation. Capacitor voltage ripple is inversely proportional to the operating frequency. Hence, operating at low frequency necessitates employing large submodule capacitances to limit voltage ripple or the utilization of energy equalization modules (EEMs). The first option negatively affects converter lifetime, and the second option requires a large number of semiconductor devices and isolating transformers. In this article, a modified MMC topology with self-energy equalization is proposed to ensure converter operation with balanced capacitor voltages with low ripple during zero-/low-frequency conditions. Operating with balanced capacitor voltages with low ripple is achieved by maintaining the same energy level in the involved upper and lower arms. A low device count alternative to the EEMs approach is proposed in this work. Detailed illustration of the operational concept and design of the associated passive components is presented. The performance of the proposed medium voltage ac drive is elucidated through simulation and experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
22. A modular multilevel DC‐DC converter with self‐energy equalization for DC grids.
- Author
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Elserougi, Ahmed, Abdelsalam, Ibrahim, Massoud, Ahmed, and Ahmed, Shehab
- Subjects
DIRECT currents ,ELECTRIC power distribution grids ,RENEWABLE energy sources ,VOLTAGE-frequency converters ,BIPOLAR transistors ,CAPACITORS - Abstract
Medium‐/High Voltage DC grids are interesting for the integration of renewable energy sources. DC‐DC conversion systems are highly needed for the development of DC grids. Recently, Modular Multilevel Converter (MMC) is the most promising technology for medium‐/high‐voltage applications, but employing the conventional MMC with DC output voltage leads to diversion in the Submodule (SM) capacitor voltages, that is energy drift. This paper proposes a modified modular multilevel DC‐DC converter with self‐energy equalization, which ensures successful DC‐DC conversion with balanced capacitors voltages. In the modified topology, clamping Insulated Gate Bipolar Transistors (IGBTs) are employed in each arm to enable parallel‐connection of the capacitors in the same arm. During the operation (equalization period), the parallel‐connected upper capacitors are connected to the parallel‐connected lower capacitors in each leg through a small limiting inductor to transfer energy between the arms to ensure balanced capacitor voltages. The proposed configuration, along with the operational concepts, mathematical analysis, and design, are presented. Finally, simulation and experimental results are presented for validation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
23. A Multiport DC–DC Converter Based on Two-Quadrant Inverter Topology for PV Systems.
- Author
-
Alajmi, Bader N., Marei, Mostafa I., and Abdelsalam, Ibrahim
- Subjects
TOPOLOGY ,ENERGY harvesting ,AC DC transformers ,DYNAMICAL systems ,INTEGRATED software ,BRIDGE circuits ,ELECTRIC inverters - Abstract
This article presents an isolated high-frequency (HF) multiport dc–dc converter for photovoltaics (PV) interfacing systems. In the proposed multiport converter, an HF transformer with multiple input windings and single output winding is utilized. Each input port is based on a proposed two-quadrant inverter topology, which connects a PV module to the HF transformer. The output port is tied to a dc bus using a rectifier. The proposed two-quadrant inverter topology prevents current flow from the ac side to the dc side. This action prevents circulating currents between different ports. Each two-quadrant inverter is controlled to harvest maximum power from its associated PV module. The analysis and operation scenarios of the proposed multiport converter are discussed. PSCAD/EMTDC software package is used to simulate the proposed PV interfacing system to investigate the operation of the proposed multiport converter topology and to examine the dynamic system behavior. In addition, an experimental prototype is developed to validate the operation scenarios of the proposed multiport dc–dc converter and to examine the performance of the presented PV interfacing system. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
24. DC–DC converter concept allowing line commutated converters and voltage source converters based HVDC systems connectivity.
- Author
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Elgenedy, Mohamed A., Ahmed, Khaled Hani, Aboushady, Ahmed A., and Abdelsalam, Ibrahim
- Subjects
VOLTAGE-frequency converters ,INSULATED gate bipolar transistors ,IDEAL sources (Electric circuits) ,TRANSISTORS ,HIGH-voltage direct current transmission ,ELECTRIC transformers - Abstract
The most common two challenges in high-voltage direct current (HVDC) multi-terminal transmission are the DC fault isolation and the DC voltage stepping up/down. Additionally, interconnecting voltage source converter (VSC)- and line commutated converter (LCC)-based HVDC network topologies has been challenging. This study introduces a new DC–DC converter topology concept connecting both LCC- and VSC-based HVDC networks with bidirectional power flow without operation stoppage. The proposed topology is formed of two front-to-front connected bridges with an AC-link formed of a capacitor and an inductor (which can be replaced by a transformer for voltage step-up/step-down). The LCC-HVDC network bridge is formed of insulated gate commutated thyristors while the VSC-HVDC network bridge is formed of insulated gate bipolar transistors. Therefore, ON/OFF switching of both bridges and bi-directional power flow are possible. Moreover, the reactive power transfer is nullified at rated active power exchange between the proposed converter bridges. The proposed concept's detailed analysis and control equations are introduced. Different operation scenarios are simulated in addition to scaled-down experimentation to test the applicability of power transfer scenarios without operation stoppage in normal operation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
25. Modular multilevel DC-DC converter with arm interchange concept.
- Author
-
Elserougi, Ahmed, Ibrahim Abdelsalam, Ibrahim, Massoud, Ahmed, and Ahmed, Shehab
- Subjects
- *
GRABENS (Geology) , *DENDRITIC cells , *ARCHITECTURAL design , *ARM , *CONCEPTS , *CAPACITORS - Abstract
Conventional modular multilevel converters (MMCs) are promising converters for high-voltage high-power applications. Unlike DC-AC conversion, DC-DC conversion of MMCs suffers from unbalanced capacitor voltages due to the energy drift problem. In this study, a new modular DC-DC converter is proposed, which consists of front-end half-bridge MMC with half-bridge submodules followed by full-bridge MMC with full-bridge submodules. The proposed modular multilevel DC-DC converter can be used effectively for connecting two different DC voltage levels in high-/medium-voltage DC grids. The proposed architecture provides successful DC-DC conversion with balanced capacitor voltages throughout the arm interchange concept. It also provides a high conversion ratio, bidirectional power flow, low losses, low current stresses, reduced number of submodules, and DC fault blocking capability. Detailed illustration, operational concept, and design of the proposed architecture with the arm interchange concept are presented. Simulation results for a high-voltage high-power DC-DC converter with the suggested approach are presented to demonstrate the system performance during different normal as well as abnormal operating conditions. Finally, a scaled-down prototype has been implemented for validation. The extracted simulation and experimental results elucidate the presented claims. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
26. Wind energy conversion system based on open-end winding three-phase PMSG coupled with ac−dc buck-boost converter.
- Author
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Abdelsalam, Ibrahim, Alajmi, Bader N., Marei, Mostafa I., and Alhajri, Mohamed F.
- Subjects
CONVERTERS (Electronics) ,WIND power ,ENERGY conversion ,ELECTRIC inverters ,IDEAL sources (Electric circuits) - Abstract
This study proposes a new back-to-back (BTB) current source converter (CSC) configuration and presents its application for variable speed wind energy conversion system. The proposed configuration consists of three cascaded ac−dc non-inverting buck-boost converter. The ac side of each converter is connected to an open-end winding of the three-phase permanent magnet synchronous generator and the dc sides are connected in parallel to a current source inverter (CSI) without the need for a dc-side capacitor. Ac−dc converters operate under discontinuous conduction mode, and they draw sinusoidal input currents at the unity power factor from fixed or variable magnitude and frequency supply. In addition, the proposed BTB CSC addresses one of the main drawbacks of the conventional CSI which is the over-voltage experienced by switches during commutation. Moreover, the switching losses of the proposed CSI are eliminated. The ElectroMagnetic Transients including DC (EMTDC)/Power System Computer Aided Design (PSCAD) software is used to assess the feasibility of the proposed topology during normal operating conditions and during low voltage ride through. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
27. Generic Closed-Loop Controller for Power Regulation in Dual Active Bridge DC–DC Converter With Current Stress Minimization.
- Author
-
Hebala, Osama M., Aboushady, Ahmed A., Ahmed, Khaled H., and Abdelsalam, Ibrahim
- Subjects
CASCADE converters ,ELECTRIC power transmission ,PHASE shift (Nuclear physics) ,CLOSED loop systems ,PARTICLE swarm optimization - Abstract
This paper presents a comprehensive and generalized analysis of the bidirectional dual active bridge (DAB) dc–dc converter using triple phase shift (TPS) control to enable closed-loop power regulation while minimizing current stress. The key new achievements are a generic analysis in terms of possible conversion ratios/converter voltage gains (i.e., Buck/Boost/Unity), per unit based equations regardless of DAB ratings, and a new simple closed-loop controller implementable in real time to meet desired power transfer regulation at minimum current stress. Per unit based analytical expressions are derived for converter ac rms current as well as power transferred. An offline particle swarm optimization (PSO) method is used to obtain an extensive set of TPS ratios for minimizing the rms current in the entire bidirectional power range of –1 to 1 per unit. The extensive set of results achieved from PSO presents a generic data pool, which is carefully analyzed to derive simple useful relations. Such relations enable a generic closed-loop controller design that can be implemented in real time avoiding the extensive computational capacity that iterative optimization techniques require. A detailed Simulink DAB switching model is used to validate the precision of the proposed closed-loop controller under various operating conditions. An experimental prototype also substantiates the results achieved. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
28. A Self-Balanced Bidirectional Medium-/High-Voltage Hybrid Modular DC–DC Converter With Low-Voltage Common DC-Link and Sequential Charging/Discharging of Submodules Capacitors.
- Author
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Elserougi, Ahmed A., Massoud, Ahmed, Abdelsalam, Ibrahim, and Ahmed, Shehab
- Subjects
DC-to-DC converters ,HIGH voltages ,SEMICONDUCTOR equipment ,CAPACITORS ,ELECTRIC potential measurement - Abstract
This paper proposes a medium-/high-voltage high-power hybrid modular dc–dc converter to interconnect two different dc-voltage levels in medium-/high-voltage dc grids. The converter consists of half-bridge submodules (SMs) rated at a moderate voltage level, i.e., series connection of semiconductor devices is avoided while connecting two high dc-voltage levels. The proposed architecture provides self-balancing operation, i.e., unlike conventional modular converters, no need for capacitor voltage measurement, which enhances the system reliability and simplicity. Sequential charging/discharging of SMs capacitors is adopted in the proposed approach to ensure a self-balanced operation. The proposed architecture can provide a high conversion ratio as well as power transfer in both directions, i.e., bidirectional dc–dc converter. Detailed illustration of the proposed approach operational concept, design, and overall control system is presented. Simulation and experimental results are presented to show the viability of the proposed configuration and validate the claims. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
29. Fast phase-shifting technique for 3-D surface micro-topography measurement.
- Author
-
Abdelsalam Ibrahim, Dahi Ghareab
- Subjects
- *
PHASE-shifting interferometry , *SAMPLING (Process) , *LAMB waves , *TOPOGRAPHY , *MEASUREMENT , *INTERFEROMETERS - Abstract
• Fast phase shift technique for rapid inspection of samples is presented. • Results were compared with those extracted by three-step phase shift. • In term of accuracy, the obtained results are not bad. • This technique can be applied for fast inspection of optoelectronic samples. This paper presents a two-step phase-shifting interferometry technique for fast inspection of uniformity of optoelectronic samples. The in-line configuration was applied to make full use of the space-bandwidth product (SBP) of the camera and hence can resolve finer spatial details of the sample. Two-step phase-shifting (TSPS) algorithm was used to reconstruct the object with only two in-line interferograms generated when a quarter wave plate (QWP) is placed in the light path of one arm of the Mach-Zehnder interferometer. Experimental results show that the extracted phases calculated by the TSPS technique match with the phases extracted by the three-step phase-shifting (THSPS) technique. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
30. Hybrid converter topologies for dc transmission systems.
- Author
-
Adam, Grain Philip, Alsokhiry, Fahad, Abdelsalam, Ibrahim, Fletcher, John, Lie Xu, and Al-Turki, Yusuf
- Subjects
DIRECT currents ,CONVERTERS (Electronics) ,INDEPENDENT system operators ,HYBRID systems ,ELECTRIC circuits - Abstract
This study presents types 1 and 2 hybrid converters with reduced power circuit complexity compared with the mixed cell modular multilevel converter (MC-MMC). The type 1 converter is formed by replacing the director switches of the alternate arm converter by high-voltage (HV) half-bridge (HB) cells rated for half of the dc-link voltage. Also, it resembles special case of MC-MMC, where the entire HB cells of each arm are lumped into a single HV HB cell, with both capacitors of the half- and fullbridge cells are exposed to fundamental current as in the conventional MMC. The upper and lower arms of the type 2 converter resemble a front-to-front connection of two three-phase hybrid cascaded two-level converters, where the cell capacitors of the three-phase two-level converters that act as director switches do not experience fundamental currents. Therefore, the type 2 converter offers compact design compared with type 1 converter and the MC-MMC. The technical viabilities of the proposed hybrid converters are assessed using simulations, with both converters modelled in MATLAB-Simulink using electromagnetic transient simulation approach, considering normal and transient conditions. Experimental results obtained from single-phase type 1 converter confirm the practical viability of the proposed converters. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
31. Modular multilevel converter with modified half-bridge submodule and arm filter for dc transmission systems with dc fault blocking capability.
- Author
-
Ahmed, Khaled H., Adam, Grain P., Abdelsalam, Ibrahim A., and Aboushady, Ahmed A.
- Subjects
DIRECT currents ,ELECTRIC potential ,HIGH-voltage direct current transmission ,ENERGY storage ,ELECTRIC transformers - Abstract
Although a modular multilevel converter (MMC) is universally accepted as a suitable converter topology for the highvoltage dc transmission systems, its dc fault ride performance requires substantial improvement in order to be used in critical infrastructures such as transnational multi-terminal dc (MTDC) networks. Therefore, this study proposes a modified submodule circuit for MMC that offers an improved dc fault ride through the performance with reduced semiconductor losses and enhanced control flexibility compared to that achievable with full-bridge submodules. The use of the proposed submodules allows MMC to retain its modularity; with semiconductor loss similar to that of the mixed submodules MMC, but higher than that of the halfbridge submodules. Besides dc fault blocking, the proposed submodule offers the possibility of controlling ac current in-feed during pole-to-pole dc short-circuit fault, and this makes such submodule increasingly attractive and useful for continued operation of MTDC networks during dc faults. The aforesaid attributes are validated using simulations performed in MATLAB/ SIMULINK and substantiated experimentally using the proposed submodule topology on a four-level small-scale MMC prototype. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
32. Self‐balanced non‐isolated hybrid modular DC–DC converter for medium‐voltage DC grids.
- Author
-
Elserougi, Ahmed A., Massoud, Ahmed M., Abdelsalam, Ibrahim, and Ahmed, Shehab
- Abstract
Here, a new bi‐directional hybrid modular non‐isolated DC–DC converter is proposed where it consists of a boost converter (BC) fed from the high‐voltage (HV) side. At the BC output stage, a certain number of half bridge submodules (HB‐SMs) is connected across the BC switch. During the turn‐on period of BC switch, the HB‐SMs are connected sequentially to the low‐voltage (LV) side, which results in charging/discharging their capacitors from/into the LV side. While, during the turn‐off period, the LV side is bypassed and the HB‐SMs capacitors are connected in series across the BC output stage, which results in discharging/charging them into/from the HV side. The power flow is controlled in both directions by controlling the duty cycle. The proposed configuration provides self‐balancing operation thanks to the sequential connection of HB‐SMs capacitors, and it also provides the ability to operate with high conversion ratios. Illustration and analysis of the proposed converter and its closed‐loop controller are presented. A full design of the values and ratings of the involved components are presented. Simulation study for a 2.5 MW (25 kV/10 kV) DC–DC converter is presented. Finally, experimental results for a downscaled prototype are presented for validation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
33. Multi-tasking dc–dc and dc–ac converters for dc voltage tapping and power control in highly meshed multi-terminal HVDC networks.
- Author
-
Adam, Grain Philip, Abdelsalam, Ibrahim, Lie Xu, Fletcher, John, Burt, Graeme, and Williams, Barry
- Subjects
HIGH-voltage direct current transmission ,VOLTAGE control ,COMPUTER multitasking ,ELECTRIC current converters ,ELECTRIC power transmission - Abstract
This study extends a recently proposed dc auto-transformer to a true multi-port converter that can function simultaneously as dc auto-transformer and a dc/ac converter for dc voltage matching and tapping, and power control in highly meshed multi-terminal dc grids. The presented multi-port converter can generate multiple adjustable dc voltages from a fixed or variable input dc voltage, or from an active ac grid. Theoretical discussions and simulations indicate that when the proposed multi-port converter is used as a hybrid dc and ac hub to manage congestions and resolve loop flow issues in a highly meshed multi-terminal dc network, large dc power can be fed to the lower dc terminal, without exposing the switching devices of the lower subconverter to excessive current stress. Its increased control flexibility and response to dc faults at high and low dc terminals are validated using simulations and experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
34. Full-Bridge Modular Multilevel Submodule-Based High-Voltage Bipolar Pulse Generator With Low-Voltage DC, Input for Pulsed Electric Field Applications.
- Author
-
Abdelsalam, Ibrahim, Elgenedy, Mohamed A., Ahmed, Shehab, and Williams, Barry W.
- Subjects
- *
PULSE generators , *HIGH voltages , *ELECTRIC fields , *TOPOLOGY , *WAVE analysis - Abstract
High-voltage (HV) pulse generators (PGs) are the core of pulsed electric field applications. Applying HV pulses produces electrical pores in a biological cell membrane, in which if the size of the pores increases beyond a critical size, the cell will not survive. This paper proposes a new HV-PG based on the modular multilevel converter with full-bridge submodules (FB-SMs). In order to alleviate the need of complicated sensorless or sensor-based voltage balancing techniques for the FB-SM capacitors, a dedicated self-regulating charging circuit is connected across each FB-SM capacitor. The individual capacitor charging voltage level is obtained from three successive stages, namely, convert the low-voltage dc input voltage to a high-frequency square ac voltage, increase the ac voltage level via a nanocrystalline step-up transformer, and rectify the secondary transformer ac voltage via a diode FB rectifier. The HV bipolar pulses are formed across the load in a fourth stage through series connected FB-SMs. The flexibility of inserting and bypassing the FB-SM capacitors allows the proposed topology to generate different pulse-waveform shapes, including rectangular waveforms with specifically reduced dv/dt and ramp pulses. The practical results, from a scaled-down experimental rig with five FB-SMs and a 1-kV peak-to-peak pulse output, validate the proposed topology. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
35. Four-Arm Three-Phase Modular Multilevel Converter (4A-TPMMC).
- Author
-
Elserougi, Ahmed A., Abdelsalam, Ibrahim, Massoud, Ahmed M., and Ahmed, Shehab
- Subjects
- *
THREE-phase alternating currents , *CONVERTERS (Electronics) , *ELECTRIC potential , *SIMULATION methods & models , *NUMBER theory - Abstract
In this paper a Four-Arm Three-Phase MMC (4A-TPMMC)-based DC–AC converter is proposed. The proposed converter generates a three-phase output voltage using a lower number of components, which reduces the converter complexity and cost. The concept of the proposed approach is presented in this paper. A comparison between the conventional Six-Arm Three-Phase MMC (6A-TPMMC) and the proposed 4A-TPMMC is conducted. Two simulation models are built, one for the 6A-TPMMC, and the other for the proposed 4A-TPMMC. The simulations are carried out for the same number of submodules per arm and the same AC output voltage magnitude. Moreover, a case study using the proposed 4A-TPMMC, as a three-phase medium voltage motor drive, is considered. Finally, an experimental validation for the proposed 4A-TPMMC is presented to prove the viability of the claimed contributions. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
36. New Efficient Submodule for a Modular Multilevel Converter in Multiterminal HVDC Networks.
- Author
-
Adam, Grain Philip, Abdelsalam, Ibrahim, Fletcher, John Edward, Burt, Graeme M., Holliday, Derrick, and Finney, Stephen Jon
- Subjects
- *
CONVERTERS (Electronics) , *HIGH-voltage direct current converters , *ELECTRIC potential , *POWER electronics , *HARMONIC analysis (Mathematics) , *ELECTRIC power systems - Abstract
In high-voltage applications, the magnitude of total semiconductor losses (on-state and switching) determines the viability of modular-type multilevel converters. Therefore, this paper presents a new cell arrangement that aims to lower total semiconductor loss of the modular multilevel converter (MMC) to less than that of the half-bridge modular multilevel converter (HB-MMC). Additional attributes of the proposed cell are: it eliminates the protective thyristors used in conventional half-bridge cells that deviate part of the dc-fault current away from the antiparallel diode of the main switch when the converter is blocked during a dc short-circuit fault, and it can facilitate continued operation of the MMC during cell failures without the need for a mechanical bypass switch. Thus, the MMC that uses the proposed cell retains all advantages of the HB-MMC such as full modularity of the power circuit and internal fault management. The claimed attributes of the proposed cell are verified using illustrative simulations and reduced scale experimentations. Additionally, this paper provides brief and critical discussions that highlight the attributes and limitations of popular MMC control methods and different MMC cells structures proposed in the literature, considering the power electronic system perspective. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
37. A Full-Bridge Submodule-Based Modular Unipolar/Bipolar High-Voltage Pulse Generator With Sequential Charging of Capacitors.
- Author
-
Elserougi, Ahmed A., Abdelsalam, Ibrahim, Massoud, Ahmed M., and Ahmed, Shehab
- Subjects
- *
ELECTRIC field strength , *PULSE generators , *CAPACITORS , *FIELD-effect transistors , *ELECTROMAGNETIC pulses - Abstract
Repetitive high pulsed electric field (PEF) is an effective method to kill microorganisms and bacteria in water treatment applications. The PEF can be generated by applying high-power electromagnetic pulse across the sample to be treated. There are two main types of high-voltage pulse generators, namely, unipolar and bipolar. In this paper, a full-bridge submodule-based modular high-voltage pulse generator, having the ability to generate unipolar and bipolar high-voltage pulses with different shapes from a relatively low-voltage input dc supply, is proposed. In the proposed configuration, relatively low-voltage insulated gate bipolar transistors (IGBTs) are required to generate the high-voltage bipolar pulses. A thyristor rated at the level of the pulsed output voltage is required in the proposed configuration to bypass the load during the charging process of capacitors. In the proposed approach, a thyristor is used instead of the self-commutated high-voltage switch (e.g., series-connected IGBTs), as thyristors are available with high-voltage ratings and possess inherent reverse voltage blocking capability. A detailed illustration of the proposed configuration and its operational concept are introduced in this paper. Simulation and experimental results are presented to validate the proposed approach. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
38. Current source back-to-back converter for wind energy conversion systems.
- Author
-
Abdelsalam, Ibrahim, Adam, Grain Philip, and Williams, Barry W.
- Subjects
WIND power ,ENERGY conversion ,ELECTROMAGNETISM ,PERMANENT magnets ,COMPUTER-aided design - Abstract
This study proposes a new back-to-back current source converter (BTB-CSC) suitable for medium-voltage high power wind energy conversion systems (WECSs). It employs a dual three-phase permanent magnet synchronous generator and two current source inverters with a phase-shift transformer at the grid side. The proposed BTB-CSC has the following advantages: reduced power circuit and control complexity; low switching losses (zero switching losses at the inverter side); and independent control of active and reactive powers. Power system computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) simulations are used as to assess the steady state and dynamic behaviour of the proposed system under different operating conditions. It is shown that the proposed WECS can ride-through ac faults. Experimental results from scaled prototype of the proposed WECS are used to validate the simulations. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
39. Three‐phase ac–dc buck–boost converter with a reduced number of switches.
- Author
-
Abdelsalam, Ibrahim, Adam, Grain P., Holliday, Derrick, and Williams, Barry W.
- Abstract
A single‐switch, single‐stage, three‐phase ac–dc buck–boost converter suitable for medium‐voltage applications is proposed. Basic relations that govern steady‐state converter operation are established, confirmed using PSCAD/EMTDC simulations, and substantiated experimentally. Simulation and experimental results establish that the proposed converter has good dynamic performance in buck and boost modes, with near unity input power factor. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
40. Hybrid Multilevel Converter With Cascaded H-bridge Cells for HVDC Applications: Operating Principle and Scalability.
- Author
-
Adam, G. P., Abdelsalam, Ibrahim Abdallah, Ahmed, Khaled Hani, and Williams, Barry W.
- Subjects
- *
CASCADE converters , *HIGH-voltage direct current transmission , *SCALABILITY , *PERFORMANCE evaluation , *SEMICONDUCTORS , *SHORT circuits - Abstract
Hybrid multilevel converters are contemplated in an attempt to optimize the performance of voltage source converters in terms of magnitude of semiconductor losses and converter footprint, and to achieve additional features such as dc short circuit proof, which is essential for a high integrity multiterminal HVDC grid. Therefore, this paper considers an emerging hybrid cascaded converter that offers the dc side short circuit proof feature at reduced loss and footprint compared to the existing multilevel and other hybrid converters. Its operating principle, modulation, and capacitor voltage balancing strategies are described in detail. Furthermore, hybrid converter scalability to high voltage applications is investigated. The validity of the modulation and capacitor voltage strategy presented are confirmed using simulation and experimentation. The hybrid cascaded converter is extendable to a large number of cells, making it applicable to high voltage applications, and operation is independent of modulation index and power factor. On these ground, the converter is expected to be applicable for both real and reactive power applications. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
41. Modified back-to-back current source converter and its application to wind energy conversion systems.
- Author
-
Abdelsalam, Ibrahim, Adam, Grain Philip, Holliday, Derrick, and Williams, Barry W.
- Subjects
WIND energy conversion systems ,IDEAL sources (Electric circuits) ,CASCADE converters ,UNINTERRUPTIBLE power supply ,HIGH voltages - Abstract
The back-to-back (BTB) converter is used in power conversion applications such as machine drives, wind energy conversion systems (WECS), uninterruptible power supplies and high-voltage, direct current transmission systems. Various topologies have evolved around voltage source converters and current source converters (CSCs) in an attempt to meet various design and reliability constraints. This paper proposes a new CSC-based BTB converter suitable for WECS application. The proposed configuration addresses the main drawbacks of the conventional BTB CSCs, such as the over-voltage frequently experienced by switches during commutation. The inverter side converter has zero switching losses. The proposed WECS offers the following advantages: simple and easy control, reduced switching frequency and maximum power point tracking with controllable grid active and reactive power. A low-voltage ride-through (LVRT) solution is also provided in the proposed WECS. PSCAD/EMTDC simulation is used to assess the steady-state and dynamic behaviours of the proposed system under different operating conditions and during LVRT. Experimental results allow steady-state and dynamic behaviour assessment of the proposed system under different operating conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
42. Single-stage, single-phase, ac-dc buck-boost converter for low-voltage applications.
- Author
-
Abdelsalam, Ibrahim, Adam, Grain P., Holliday, Derrick, and Williams, Barry W.
- Subjects
SINGLE-stage accelerators ,AC DC transformers ,CASCADE converters ,LOW voltage systems ,COMPUTER-aided design - Abstract
The suitability of a single-stage ac-dc buck-boost converter for low-voltage applications is investigated. In-depth discussion and analysis of the converter's operating principle, basic relationships that govern converter steady-state operation and details of the necessary control structures needed to comply with the grid code are provided. The validity of the proposed system is confirmed using power system computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) simulations, and is substantiated experimentally. The buck-boost converter under investigation has good dynamic performance in both buck and boost modes, and ensures near unity input power factor over the full operating range, whilst having fewer devices and passive elements than other published versions of the buck-boost converter. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
43. Modified Variable Step-Size Incremental Conductance MPPT Technique for Photovoltaic Systems.
- Author
-
Owusu-Nyarko, Isaac, Elgenedy, Mohamed A., Abdelsalam, Ibrahim, and Ahmed, Khaled H.
- Subjects
MAXIMUM power point trackers ,PHOTOVOLTAIC power systems ,ALGORITHMS - Abstract
A highly efficient photovoltaic (PV) system requires a maximum power point tracker to extract peak power from PV modules. The conventional variable step-size incremental conductance (INC) maximum power point tracking (MPPT) technique has two main drawbacks. First, it uses a pre-set scaling factor, which requires manual tuning under different irradiance levels. Second, it adapts the slope of the PV characteristics curve to vary the step-size, which means any small changes in PV module voltage will significantly increase the overall step-size. Subsequently, it deviates the operating point away from the actual reference. In this paper, a new modified variable step-size INC algorithm is proposed to address the aforementioned problems. The proposed algorithm consists of two parts, namely autonomous scaling factor and slope angle variation algorithm. The autonomous scaling factor continuously adjusts the step-size without using a pre-set constant to control the trade-off between convergence speed and tracking precision. The slope angle variation algorithm mitigates the impact of PV voltage change, especially during variable irradiance conditions to improve the MPPT efficiency. The theoretical investigations of the new technique are carried out while its practicability is confirmed by simulation and experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
44. Analysis and Design of a Multi-Port DC-DC Converter for Interfacing PV Systems.
- Author
-
Alajmi, Bader N., Marei, Mostafa I., Abdelsalam, Ibrahim, AlHajri, Mohamed F., and Flicker, Jack
- Subjects
MAXIMUM power point trackers ,COMPUTER-aided design ,PHOTOVOLTAIC power systems ,COMPUTER systems ,BUILDING performance ,ARTIFICIAL satellite tracking - Abstract
A high-frequency multi-port (HFMP) direct current (DC) to DC converter is presented. The proposed HFMP is utilized to interface a photovoltaic (PV) system. The presented HFMP is compact and can perform maximum power point tracking. It consists of a high-frequency transformer with many identical input windings and one output winding. Each input winding is connected to a PV module through an H-bridge inverter, and the maximum PV power is tracked using the perturb and observe (P&O) technique. The output winding is connected to a DC bus through a rectifier. The detailed analysis and operation of the proposed HFMP DC-DC converter are presented. Extensive numerical simulations are conducted, using power system computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) software, to evaluate the operation and dynamic behavior of the proposed PV interfacing scheme. In addition, an experimental setup is built to verify the performance of the HFMP DC-DC converter. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
45. High-power medium-voltage three-phase ac–dc buck–boost converter for wind energy conversion systems.
- Author
-
Alsokhiry, Fahad, Abdelsalam, Ibrahim, Adam, Grain Philip, and Al-Turki, Yusuf
- Subjects
- *
WIND energy conversion systems , *AC DC transformers , *SWITCHING power supplies - Abstract
• This paper proposes topologies A,B and C of acdc buck–boost converters for MV applications, with 'A' and 'C' have been identified as promising. • Topologies 'A' and 'C' facilitate scalability to higher and lower MV applications, with 'C' uses a novel parallel charging of inductors. • The theoretical principles that underpin the operation of the proposed topologies are established and verified using simulations and experiments. This paper proposes three topologies of single-stage three-phase ac–dc buck–boost converters suitable for medium-voltage and high-power wind energy conversion systems (WECS). The proposed converters draw sinusoidal input currents with nearly unity power factor from wind generators over wide range of ac voltages and frequencies. The proposed converters reduce the voltage and current stresses on the self-commutated switching device compared to existing solutions; thus, promising for new generation of relatively cheap WECSs. The proposed converters operate in Discontinuous Condition Mode (DCM), with their ac terminals connected to three-phase generator with open ended windings, or to ac supply using three single-phase transformers with isolated windings at converter side. The validity of the proposed converters and its detailed theoretical analysis and discussions are confirmed using PSCAD/EMTDC simulations, and further corroborated by experimentations, considering different operating conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
46. Tissue and serum EGFR as prognostic factors in malignant pleural mesothelioma
- Author
-
Gaafar, Rabab, Bahnassy, Abeer, Abdelsalam, Ibrahim, Kamel, Mahmoud M., Helal, Amani, Abdel-Hamid, Amany, Eldin, Nelly Aly, and Mokhtar, Nadia
- Subjects
- *
EPIDERMAL growth factor , *CELL receptors , *CANCER prognosis , *MESOTHELIOMA , *SERUM , *TISSUES , *CELLULAR signal transduction , *GENE expression - Abstract
Abstract: Background: Malignant pleural mesothelioma (MPM) is an asbestos related aggressive tumor. Asbestos causes genetic modifications and cell signaling events that favor resistance to chemotherapy. A variety of receptor tyrosine kinases have been identified to play a central role in various aspects of tumorigenesis. Epidermal growth factor receptor (EGFR) is overexpressed in a variety of epithelial malignancies including lung cancer in which EGFR aberrations not only predict response to EGFR tyrosine kinase inhibitors but also indicate tumor progression. However in MPM, the role of EGFR is less clear. This study was designed to identify serum and tissue EGFR levels in patients with MPM and to evaluate the relationship between serum and tissue EGFR levels and clinicao-pathological prognostic factors and survival. Methods: We investigated 71 cases of MPM for EGFR expression in tissue. Serum EGFR was assessed in 40 out of those 71 cases and 20 healthy subjects as a control. Pre-treatment serum EGFR levels were measured using quantitative enzyme-linked immunosorbent assay. Tissue EGFR protein overexpression was assessed by immunohistochemistry and gene amplification was assessed by the chromogen in situ hybridization (CISH) technique. Results were correlated with the clinical–pathological factors of the patients and overall survival (OS). Results: Out of the 71 patients included in the study, 19 had undergone extrapleural pneumonectomy. As for the rest of the patients, 46 received chemotherapy while 6 had only best supportive care. EGFR immuno-reactivity was detected in 74.6% of the cases, 37 (52.1%) cases were positive for EGFR gene amplification by CISH, 31 of them revealed moderate to high (++, +++) EGFR immuno-reactivity. Elevated serum EGFR >2.5ng/ml (the median concentration of EGFR in MPM) was reported in 45% of the cases. The overall response rate (RR) for the 46 treated patients who received chemotherapy was 24.1%. After a median follow up of 29 months, the median overall survival (OS) was 10 months. Elevated serum and tissue EGFR is significantly associated with advanced disease stage. However neither EGFR overexpression in tissues nor high serum levels were associated with survival rates. Conclusions: EGFR expression is a common feature in MPM patients. High pre-treatment levels of serum EGFR are associated with advanced stage but not with reduced OS. Detailed mutational analysis of EGFR on a larger number of patients is still needed to clarify the exact role of EGFR in MPM patients. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
47. 'Corrigendum to "Development of eco-friendly nanoemulsions of some natural oils and evaluating of its efficiency against postharvest fruit rot fungi of cucumber" [Ind. Crops Prod. 159 (2021) 113049]'.
- Author
-
Mossa, Abdel-Tawab H., Mohafrash, Samia M.M., Ziedan, El-Sayed H.E., Abdelsalam, Ibrahim S., and Sahab, Ahmed F.
- Subjects
- *
FRUIT rots , *CUCUMBERS , *CROPS , *FUNGI - Published
- 2022
- Full Text
- View/download PDF
48. Development of eco-friendly nanoemulsions of some natural oils and evaluating of its efficiency against postharvest fruit rot fungi of cucumber.
- Author
-
Mossa, Abdel-Tawab H., Mohafrash, Samia M.M., Ziedan, El-Sayed H.E., Abdelsalam, Ibrahim S., and Sahab, Ahmed F.
- Subjects
- *
FRUIT rots , *FUNGAL spores , *ANTIFUNGAL agents , *CUCUMBERS , *LEMON , *ESSENTIAL oils , *OILSEEDS - Abstract
• Nanoemulsions of some natural oils i.e., clove, black seed, orange and lemon and their fungicidal activity against postharvest fruit rot of cucumber were prepared and studied. • Nanoformulations of clove and black seed essential oils (2:1) reduced mycelial linear growth, andcompletely inhibited (100%) conidia sporulation of fungal isolates. • Nanoformulation of clove and black seed essential oils (2:1) respectively is a promising safe alternative fungicide for application against postharvest rot of cucumber fruits management. There are growing concerns about the extensive use of synthetic fungicides worldwide due to their negative health effect on humans, ecosystem, and the development of fungal resistance. Therefore, developing new and safe eco-friendly antifungal agents such as plant-based oils is of major interest. This study was conducted for the first time to develop and evaluate the efficiency of eco-friendly nanoemulsions of some natural oils and evaluating of its efficiency against postharvest fruit rot of cucumber caused by the following fungal isolates: Galactomyces candidum (MF373433), Alternaria tenuissima (MF 373440) and Fusarium solani (MF373443). Nanoemulsions of clove, black seed, lemon, and orange oils were formulated by using ultrasound and subjected to physicochemical and stability studies. The efficiency of these nanoemulsions was evaluated against the postharvest fruit rot fungi of cucumber. The oils of promising nanoemulsions have been analyzed by gas chromatography-mass spectrometry analysis (GC/MS). The acute toxicity study was conducted on rats and on the luminescence emitted of Vibrio fischeri bacteriausing Microtox®. The smaller droplet size of nanoemulsions was found after 10 min of sonication with an oil to Tween 80 ratio of 1:1 and 1:2 for clove and black seed oils, respectively. Nanoemulsion of black seed and clove oils from Egypt at 5000 ppm showed a significantly high reduction in the linear mycelial growth of fungal isolates. The mixture formula (2:1 v/v) of nanoemulsions of clove and black seed oils showed a significantly high reduction in linear mycelial growth, completely inhibited (100%) conidia sporulation of fungal isolates, and highly reduced the percentage of the rot of germinated seeds as well mortality of cucumber developed seedlings. Nanoemulsion formulation of clove and black seed (2:1) at concentration 2.0 % as soaking treatment of cucumber fruits before artificial infestation by inocula of fungal pathogens caused completely (100%) suppress postharvest fruit rot of cucumber. Both clove and black seed oils nanoemulsions and their combination showed no signs of toxicity or mortality in rats and no toxic effects on the luminescence emitted of Vibrio fischeri bacteria using Microtox® assay. Therefore, it can be concluded that the nanoformulation of clove and black seed oils at the ratio of 2:1 is a promising green and safe alternative to synthetic fungicide for application against postharvest rot of cucumber fruits. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
49. Au@AuPd Core-Alloyed Shell Nanoparticles for Enhanced Electrocatalytic Activity and Selectivity under Visible Light Excitation.
- Author
-
da Silva KN, Shetty S, Sullivan Allsop S, Cai R, Wang S, Quiroz J, Chundak M, Dos Santos HLS, Abdelsalam I, Oropeza FE, de la Peña O'Shea VA, Heikkinen N, Sitta E, Alves TV, Ritala M, Huo W, Slater TJA, Haigh SJ, and Camargo PHC
- Abstract
Plasmonic catalysis has been employed to enhance molecular transformations under visible light excitation, leveraging the localized surface plasmon resonance (LSPR) in plasmonic nanoparticles. While plasmonic catalysis has been employed for accelerating reaction rates, achieving control over the reaction selectivity has remained a challenge. In addition, the incorporation of catalytic components into traditional plasmonic-catalytic antenna-reactor nanoparticles often leads to a decrease in optical absorption. To address these issues, this study focuses on the synthesis of bimetallic core@shell Au@AuPd nanoparticles (NPs) with ultralow loadings of palladium (Pd) into gold (Au) NPs. The goal is to achieve NPs with an Au core and a dilute alloyed shell containing both Au and Pd, with a low Pd content of around 10 atom %. By employing the (photo)electrocatalytic nitrite reduction reaction (NO
2 RR) as a model transformation, experimental and theoretical analyses show that this design enables enhanced catalytic activity and selectivity under visible light illumination. We found that the optimized Pd distribution in the alloyed shell allowed for stronger interaction with key adsorbed species, leading to improved catalytic activity and selectivity, both under no illumination and under visible light excitation conditions. The findings provide valuable insights for the rational design of antenna-reactor plasmonic-catalytic NPs with controlled activities and selectivity under visible light irradiation, addressing critical challenges to enable sustainable molecular transformations.- Published
- 2024
- Full Text
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50. High-precision 3D surface topography measurement using high-stable multi-wavelength digital holography referenced by an optical frequency comb.
- Author
-
Abdelsalam Ibrahim DG and Yasui T
- Abstract
High-stable, two-wavelength, digital holography referenced by an optical frequency comb is presented. The technique is demonstrated by using optical waves from an external cavity laser diode phase-locked to a mode-locked Er-doped fiber comb laser light. The mixed beat signal is stabilized at 30 MHz by a sensitive proportional integral derivative controller. The tunable continuous-waves stabilized with frequency uncertainty of 5×10
-11 are employed to investigate large stepped structures.- Published
- 2018
- Full Text
- View/download PDF
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