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Fathy, Khairy,Morimoto, Keiki,Suh, Ki-Young,Kwon, Soon-Kurl,Nakaoka, Mutsuo The Korean Institute of Electrical Engineers 2007 Journal of Electrical Engineering & Technology Vol.2 No.1
This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed half-bridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC buslines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the frequency range of 60 kHz under the principle of soft switching. The performance evaluations of the experimental setup are illustrated practically. The effectiveness of this new converter topology is proved for such low voltage and large current DC-DC power supplies as DC bus feeding from a practical point of view.
Fathy, Khairy,Kwon, Soon-Kurl,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.3
In this paper, a novel type auxiliary active edge resonant snubber assisted zero current soft switching pulse modulation Single-Ended Push Pull (SEPP) series load resonant inverter using IGBT power modules is proposed for cost effective consumer high-frequency induction heating (IH) appliances. Its operating principle in steady state is described by using each switching mode's equivalent operating circuits. The new multi resonant high-frequency inverter with series load resonance and edge resonance can regulate its high frequency output power under a condition of a constant frequency zero current soft switching (ZCS) commutation principle on the basis of the asymmetrical pulse width modulation (PWM) control scheme. Brand-new consumer IH products using the proposed ZCS-PWM series load resonant SEPP high-frequency inverter using IGBTs is evaluated and discussed as compared with conventional high-frequency inverters on the basis of experimental results. In order to extend ZCS operation ranges under a low power setting PWM as well as to improve efficiency, the high frequency pulse density modulation (PDM) strategy is demonstrated for high frequency multi-resonant inverters. Its practical effectiveness is substantially proved from an application point of view.
Reinforced Connection for Upgrading Strength and Efficiency of Single Angle Tension Members
Fathy Abdelmoniem Abdelfattah,Ali Abdel Hakam Ali abdo 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.2
Single angle tension members are commonly connected by bolting through one leg. Stress concentration and shear lag effects promote the angle failure at the connection region. This angle failure reduces the angle ultimate tensile strength and efficiency of the material. This study proposes a reinforced connection to upgrade the single angle tension strength of the member and its material efficiency. A lug angle was nested into the angle member and bolted to the gusset plate and the angle by the lead bolt in the connection. At some distance, the outstanding legs of the angle and lug angle were bolted. A total of 17 specimens were fabricated and tested until failure. Finite element analysis was performed to model the behavior of the tested specimens and to study the different parameters that may affect the connection's capacity. The proposed reinforced connection increased the tensile strength of the angle and the angle material efficiency by up to 35%. An empirical formula was proposed, and design recommendations are presented.
Fathy, I.,Amory-Mazaudier, C.,Fathy, A.,Mahrous, A. M.,Yumoto, K.,Ghamry, E. American Geophysical Union 2014 JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS Vol.119 No.5
In this paper we study the planetary magnetic disturbance during the magnetic storm occurring on 5 April 2010 associated with high-speed solar wind stream due to a coronal hole following a coronal mass ejection. We separate the magnetic disturbance associated to the ionospheric disturbance dynamo (Ddyn) from the magnetic disturbance associated to the prompt penetration of magnetospheric electric field (DP2). This event exhibits different responses of ionospheric disturbance dynamo in the different longitude sectors (European-African, Asian, and American). The strongest effect is observed in the European-African sector. The Ddyn disturbance reduces the amplitude of the daytime H component at low latitudes during four consecutive days in agreement with the Blanc and Richmond's model of ionospheric disturbance dynamo. The amplitude of Ddyn decreased with time during the 4days. We discuss its diverse worldwide effects. The observed signature of magnetic disturbance process in specific longitude sector is strongly dependent on which Earth's side faces the magnetic storms (i.e., there is a different response depending on which longitude sector is at noon when the SSC hits). Finally, we determined an average period of 22h for Ddyn using wavelet analysis.
A Novel Quasi-Resonant Snubber-Assisted ZCS-PWM DC-DC Converter with High Frequency Link
Fathy, Khairy,Kwon, Soon-Kurl The Korean Institute of Power Electronics 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.2
In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM resonant DC-DC converter with two simple auxiliary commutation lossless inductor snubbers is presented. The operation principle of this converter is described using the switching mode equivalent circuits. This newly developed multi resonant DC-DC converter can regulate its DC output AC power under a principle of constant frequency edge-resonant soft switching commutation by an asymmetrical PWM duty cycle control scheme. The high frequency power regulation and actual power characteristics of the proposed soft switching PWM resonant DC-DC converter are evaluated and discussed. The operating performances of the newly proposed soft switching inverter are represented based on simulation results from an applications point of view.
Khairy Fathy,Keiki Morimoto,Ki-Young Suh,Soon-Kurl Kwon,Mutsuo Nakaoka 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.1
This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed half-bridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC buslines can achieve ZCS tum-on and ZVS tum-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the frequency range of 60 ㎑ under the principle of soft switching. The performance evaluations of the experimental setup are illustrated practically. The effectiveness of this new converter topology is proved for such low voltage and large current DC-DC power supplies as DC bus feeding from a practical point of view.
Simplified methods of the 3D-SVPWM for four-wire three-leg inverter
Awad, Fathy H.,Mansour, Ahmed A.,Marei, Mostafa I.,El-Sattar, Ahmed A. The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6
This paper introduces a novel technique for simplification of a three-dimension space vector pulse width modulation (3D-SVPWM). Conventional SVPWM calculations are based on trigonometric functions or several decomposition matrices. Thus, a very fast embedded controller is needed either for two-dimension space vector pulse width modulation (2D-SVPWM) or 3D-SVPWM. The proposed simplified 3D-SVPWM is dedicated to four-wire three-leg inverters. This technique is based on first-order equations of the curve fitting technique to reduce calculation time. Therefore, this method can be implemented with low memory storage and Central Processing Unit (CPU) capability. In addition, high accuracy can be achieved using higher-order equations. Many approaches are introduced for simplifications. The applications of the proposed simplified 3D-SVPWM method are also provided. Simulation results of the proposed simplified 3D-SVPWM and the conventional 3D-SVPWM are discussed. Finally, the results are verified using a real-time simulator based on Typhoon device (402) as Hardware-In-the-Loop. In addition, the controller of the simplified method is implemented and operated on the C2000 LAUNCHXL-F28379D as a low-cost microcontroller kit.
Novel of Arabic woman: development and basic issues
( Alaaeldien Fathy Mohamed Elgabry ) 한국외국어대학교 중동연구소 2015 중동연구 Vol.34 No.1
This paper studies a sample of novels written by Arab women writers and discussing women’s issues. It depends on the findings of narratology to reveal social, cultural, and political issues related to women’s causes. This paper pays attention to the phase of beginnings, and studies Amina Alsaeed’s The Willful Woman and the social adventures of the woman mentioned in the title of this novel. It also studies the novel The Mother of Kings which deviates from historical reality, and resorts to allusion and indirect references. In the last phase, issues have become numerous and direct, and this phase deals with the revolt of women. It shows a wider scope for bold novelistic treatment. The novels which belong to this phase include Dariah, A Rose Empty Shirt, Hallucinations, etc. The issues and causes discussed in the novels written by Arab women writers have crystalized over time. These writers have managed to express their important issues and causes in their novels.
A Novel Quasi-Resonant Snubber Assisted ZCS-PWM Soft-Switching DC-DC Converter
Khairy Fathy,Hyun Woo Lee,Mutsuo Nakaoka 전력전자학회 2006 전력전자학술대회 논문집 Vol.- No.-
In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM resonant DC-DC Converter with two simple auxiliary commutation lossless inductor snubbers. The operation principle of this converter is described using the switching mode equivalent circuits. This newly developed multi resonant DC-DC Converter can regulate its dc output AC power under a principle of constant frequency edge-resonant soft switching commutation by asymmetrical PWM duty cycle control scheme. The high frequency power regulation and actual power characteristics of the proposed soft switching PWM resonant DC-DC Converter are evaluated and discussed. The operating performances of the newly proposed soft switching inverter are represented based on simulation a results from an application point of view.