Steady State and Transient Analysis of Switched Reluctance Motor Drive Fed from a Controlled AC-DC Rectifier

Moussa, Mona Fouad The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.8 No.1

The Theory of operation of switched reluctance motors (SRM) depends on the reluctance torque, where energy is transferred to stator winding only. Although its construction is simple, the electrical design is complex, due to the switching configuration needed to deliver power to stator coils. However, because of the nonlinearly of magnetic circuit, SRM has torque ripple. This paper proposes a new strategy to drive SRM from a single-phase AC supply. Each stator winding is connected to AC-DC or AC-AC converters, which is called branch. All branches are connected in parallel to a single-phase AC supply. A shaft encoder allows current production in stator winding during the positive torque production region and terminates it during the negative torque production region. A magnetic flux is produced between stator poles when current is supplied from AC supply to stator coil and repeats many cycles as long as the rate of change of stator inductance is positive. Different possibilities for the configurations of AC-AC or AC-DC converters are introduced to drive SRM from the single-phase AC supply. A case study is presented for a SRM fed from AC supply through semi-controlled AC-DC converter is presented. A simulation model is introduced and verified by experimental rig for two-phase SRM.

Selective Harmonic Elimination in Multi-level Inverters with Series-Connected Transformers with Equal Power Ratings

Moussa, Mona Fouad,Dessouky, Yasser Gaber The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a single-phase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.

Selective Harmonic Elimination in Multi-level Inverters with Series-Connected Transformers with Equal Power Ratings

Mona Fouad Moussa,Yasser Gaber Dessouky 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a singlephase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.

Buckling behavior of a single-layered graphene sheet resting on viscoelastic medium via nonlocal four-unknown integral model

Moussa Bellal,Habib Hebali,Houari Heireche,Abdelmoumen Anis Bousahla,Abdeldjebbar Tounsi,Fouad Bourada,S.R. Mahmoud,E.A. Adda Bedia,Abdelouahed Tounsi 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.5

In the present work, the buckling behavior of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak’s medium is studied using nonlocal four-unknown integral model. This model has a displacement field with integral terms which includes the effect of transverse shear deformation without using shear correction factors. The visco-Pasternak’s medium is introduced by considering the damping effect to the classical foundation model which modeled by the linear Winkler’s coefficient and Pasternak’s (shear) foundation coefficient. The SLGS under consideration is subjected to compressive in- plane edge loads per unit length. The influences of many parameters such as nonlocal parameter, geometric ratio, the visco-Pasternak’s coefficients, damping parameter, and mode numbers on the buckling response of the SLGSs are studied and discussed.

Power Management of Open Winding PM Synchronous Generator for Unbalanced Voltage Conditions

EL-Bardawil, Ashraf,Moussa, Mona Fouad The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

Wind energy is currently the fastest-growing electricity source worldwide. The cost efficiency of wind generators must be high because these generators have to compete with other energy sources. In this paper, a system that utilizes an open-winding permanent-magnet synchronous generator is studied for wind-energy generation. The proposed system controls generated power through an auxiliary voltage source inverter. The VA rating of the auxiliary inverter is only a fraction of the system-rated power. An adjusted control system, which consists of two main parts, is implemented to control the generator power and the grid-side converter. This paper introduces a study on the effect of unbalanced voltages for the wind-generation system. The proposed system is designed and simulated using MATLAB/Simulink software. Theoretical and experimental results verify the validity of the proposed system to achieve the power management requirements for balanced and unbalanced voltage conditions of the grid.

Power Management of Open Winding PM Synchronous Generator for Unbalanced Voltage Conditions

Ashraf EL- Bardawil,Mona Fouad Moussa 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

Wind energy is currently the fastest-growing electricity source worldwide. The cost efficiency of wind generators must be high because these generators have to compete with other energy sources. In this paper, a system that utilizes an open-winding permanent-magnet synchronous generator is studied for wind-energy generation. The proposed system controls generated power through an auxiliary voltage source inverter. The VA rating of the auxiliary inverter is only a fraction of the system-rated power. An adjusted control system, which consists of two main parts, is implemented to control the generator power and the grid-side converter. This paper introduces a study on the effect of unbalanced voltages for the wind-generation system. The proposed system is designed and simulated using MATLAB/Simulink software. Theoretical and experimental results verify the validity of the proposed system to achieve the power management requirements for balanced and unbalanced voltage conditions of the grid.

Surgical outcomes of laparoscopic trachelectomy following supracervical hysterectomy: a multicenter study

Ayman Shehata Dawood,Heba Fouad Harras,Hossam Ramadan Moussa,Ahmed Saber Soliman 대한산부인과학회 2022 Obstetrics & Gynecology Science Vol.65 No.6

ObjectiveTo evaluate the feasibility, safety, and surgical outcomes of laparoscopic trachelectomy after supracervical hysterectomy. MethodsThis multicenter study was conducted at Tanta University, Benha University, and Aminah Laparoscopy Center (Benha,Egypt) from June 1, 2018 to October 31, 2021. Forty patients were recruited for this study and counseled on laparoscopictrachelectomy to treat their symptoms after supracervical hysterectomy. Furthermore, cervical biopsy was performedto detect and exclude any malignancy. Histopathological examination of cervical specimens was performedafter surgery. Operative details and outcomes were recorded. ResultsThe median age of the patients was 42 years (range, 38-47). The median body mass index was 25 years (range, 22-28). The median interval between hysterectomy and the clinical presentation was 4.40 years (range, 3.58-5.25). Mostpatients presented with abnormal vaginal discharge (40%) and bleeding (25%). Moreover, a cervical biopsy result revealedstump carcinoma in three cases (7.5%) that were excluded. The median operative time was 210 minutes (range,170-220). The median blood loss was 270 mL (range, 220-320). Additionally, histopathological examinations revealedthat chronic non-specific cervicitis was present in 54.05% of trachelectomy specimens. There were no significant differencesbetween symptomatic and asymptomatic patients regarding operative outcomes, except adhesions, whichwere more significantly increased in symptomatic patients (P=0.015). Minimal complications, both operative and postoperative,were related to the procedure. ConclusionAlthough the operative time was long and adhesions were common during laparoscopic trachelectomy, the procedurewas feasible and safe, with minimal complications.

Osteoactivin inhibition of osteoclastogenesis is mediated through CD44-ERK signaling

Gregory R Sondag,Thomas S Mbimba,Fouad M Moussa,Kimberly Novak,Bing Yu,Fatima A Jaber,Samir M Abdelmagid,Werner J Geldenhuys,Fayez F Safadi 생화학분자생물학회 2016 Experimental and molecular medicine Vol.48 No.-

Osteoactivin is a heavily glycosylated protein shown to have a role in bone remodeling. Previous studies from our lab have shown that mutation in Osteoactivin enhances osteoclast differentiation but inhibits their function. To date, a classical receptor and a signaling pathway for Osteoactivin-mediated osteoclast inhibition has not yet been characterized. In this study, we examined the role of Osteoactivin treatment on osteoclastogenesis using bone marrow-derived osteoclast progenitor cells and identify a signaling pathway relating to Osteoactivin function. We reveal that recombinant Osteoactivin treatment inhibited osteoclast differentiation in a dose-dependent manner shown by qPCR, TRAP staining, activity and count. Using several approaches, we show that Osteoactivin binds CD44 in osteoclasts. Furthermore, recombinant Osteoactivin treatment inhibited ERK phosphorylation in a CD44-dependent manner. Finally, we examined the role of Osteoactivin on receptor activator of nuclear factor-κ B ligand (RANKL)-induced osteolysis in vivo. Our data indicate that recombinant Osteoactivin inhibits RANKL-induced osteolysis in vivo and this effect is CD44-dependent. Overall, our data indicate that Osteoactivin is a negative regulator of osteoclastogenesis in vitro and in vivo and that this process is regulated through CD44 and ERK activation.