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A.Emadi 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
In this paper, an approach to the design of negative impedance stabilizing controllers for PWM DC/DC converters that are used in DC switching power supplies with constant power loads is presented. The control approach is based on the feedback linearization technique. Because of the negative impedance destabilizing characteristics of constant power loads, classical linear control methods have stability limitations around the operating points. However, the proposed stabilizing technique improves large-signal stability and dynamic responses. The proposed controllers are simulated and their responses under different operations are studied. Stability of the control technique is also verified using the second theorem of Lyapunov.<br/>
Control and Modulation of Three to Asymmetrical Six-Phase Matrix Converters based on Space Vectors
Mohammed A. Al-Hitmi,Khaliqur Rahman,Atif Iqbal,Nasser Al-Emadi 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
This paper proposes the modulation and control of a three-to-six-phase matrix converter with an asymmetrical six-phase output. The matrix converter (MC) outputs consist of two sets of three-phase spatially shifted by 300, where the two sets have two isolated neutrals. The space vector approach is considered for the modeling and subsequent modulation of the three-to-six phase MC. The intelligent selection of voltage space vectors is made to synthesize the reference voltages and to obtain a sinusoidal output. The dwell times of selected voltage space vectors are adjusted in such a way that the effect of the second and the third auxiliary plane vectors (i.e., x1-y1, and x2-y2) are nullified. To achieve the maximum output voltage gain and to ensure that no reactive power is drawn from the utility supply, the input side power factor is maintained at unity. Nevertheless, the source side power factor is controllable. The modulation technique is implemented in dSPACE working in conjunction with a FPGA. Hardware results that validate the proposed control algorithm are discussed.
Seyyedbehrad Emadi,Jose A. Lozano-Galant,Ye Xia,Gonzalo Ramos,Jose Turmo 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.6
Shear deformation effects are neglected in most structural system identification methods. This assumption might lead to important errors in some structures like built up steel or composite deep beams. Recently, the observability techniques were presented as one of the first methods for the inverse analysis of structures including the shear effects. In this way, the mechanical properties of the structures could be obtained from the nodal movements measured on static tests. One of the main controversial features of this procedure is the fact that the measurement set must include rotations. This characteristic might be especially problematic in those structures where rotations cannot be measured. To solve this problem and to increase its applicability, this paper proposes an update of the observability method to enable the structural identification including shear effects by measuring only vertical deflections. This modification is based on the introduction of a numerical optimization method. With this aim, the inverse analysis of several examples of growing complexity are presented to illustrate the validity and potential of the updated method.
Numerical study on the performance of corrugated steel shear walls
S.A. Edalati,M. Bayat,Y. Yadollahi,I. Pakar,A. Emadi 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.4
This paper examines the nonlinear behaviour of corrugated steel plate shear walls under lateral pushover load. One of the innovations in these types of walls which have used in recent years is the use of the corrugated steel shear walls rather un-stiffness plates. In the last decades many experimental studies have been done on the on the corrugated steel shear walls. A finite element analysis that includes both material and geometric nonlinearities is employed for the investigation. A comparison is made between the behaviour of steel shear walls with sinusoidal corrugated plate and trapezoidal corrugated plate. The effects of parameters such as the thickness of the corrugated plate, the corrugation depth in the corrugated plates and the corrugation length of the infill of the corrugated plates, are investigated. The results of this study have demonstrated that in the wall with constant dimensions, the trapezoidal plates have higher energy dissipation, ductility and ultimate bearing than sinusoidal waves, while decreasing the steel material consumption.
R. Emadi,F. Tavangarian,R. Zamani Foroushani,A. Gholamrezaie 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5
The effects of mechanical activation of a powder mixture of basic talc and periclase on the reaction rate of the formation of the forsterite structure were studied in the absence and presence of fluorine and chlorine ions. Mechanical activation with fluorine/chlorine ions caused the formation of a series of intermediate transition compounds in an explosive reaction that enhanced the forsterite fabrication rate. Fluorine/chlorine ions were released from the system by hydrolysis. Single-phase nanocrystalline forsterite powder was successfully synthesized by 1 h of mechanical activation with subsequent annealing at 1000 and 1200 oC for 1 h in the presence of fluorine ions. In the presence of chlorine ions, single-phase forsterite powder was obtained after 1 h of mechanical activation with subsequent annealing at 1200 oC for 1 h, but the crystallite size of this sample was larger than 100 nm. In the absence of these ions, forsterite can be fabricated by 5 h of mechanical activation with subsequent annealing at 1000 oC for 1 h.
Numerical study on the performance of corrugated steel shear walls
Edalati, S.A.,Yadollahi, Y.,Pakar, I.,Emadi, A.,Bayat, M. Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.4
This paper examines the nonlinear behaviour of corrugated steel plate shear walls under lateral pushover load. One of the innovations in these types of walls which have used in recent years is the use of the corrugated steel shear walls rather un-stiffness plates. In the last decades many experimental studies have been done on the on the corrugated steel shear walls. A finite element analysis that includes both material and geometric nonlinearities is employed for the investigation. A comparison is made between the behaviour of steel shear walls with sinusoidal corrugated plate and trapezoidal corrugated plate. The effects of parameters such as the thickness of the corrugated plate, the corrugation depth in the corrugated plates and the corrugation length of the infill of the corrugated plates, are investigated. The results of this study have demonstrated that in the wall with constant dimensions, the trapezoidal plates have higher energy dissipation, ductility and ultimate bearing than sinusoidal waves, while decreasing the steel material consumption.
Lyapunov-Based Fuzzy Control Scheme for Switched Reluctance Motor Drives
L.Safavian,S.Filizadeh,A.Emadi 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
In this paper, the classical Lyapunov synthesis method for designing controllers is extended to fuzzy logic. This control technique is then applied to the design of a novel tracking controller for reluctance motor drives. The main features of the method are small rule base, simplicity of construction, and low cost The proposed controller has been simulated for a model case. In addition, its dynamic performances have been shown to be satisfactory. Capabilities of the proposed technique in controlling the highly nonlinear systems of reluctance motors with much simplicity are also verified.<br/>
S. Filizadeh,L. S. Safaian,A. Emadi 전력전자학회 2002 JOURNAL OF POWER ELECTRONICS Vol.2 No.4
In this paper, two approaches for designing tracking controllers for a variable reluctance motor (VRM), namely the Lyapunov-based fuzzy approach and the classical approach, are compared The nonlinear model of a VRM is first addressed The two control schemes are introduced afterwards, and then applied to obtain tracking controllers Simulation results of a sample case, to which the methods are applied, are also presented Comparison of the methods based on the results obtained concludes the paper.<br/>
Control and Modulation of Three to Asymmetrical Six-Phase Matrix Converters based on Space Vectors
Al-Hitmi, Mohammed A.,Rahman, Khaliqur,Iqbal, Atif,Al-Emadi, Nasser The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
This paper proposes the modulation and control of a three-to-six-phase matrix converter with an asymmetrical six-phase output. The matrix converter (MC) outputs consist of two sets of three-phase spatially shifted by $30^0$, where the two sets have two isolated neutrals. The space vector approach is considered for the modeling and subsequent modulation of the three-to-six phase MC. The intelligent selection of voltage space vectors is made to synthesize the reference voltages and to obtain a sinusoidal output. The dwell times of selected voltage space vectors are adjusted in such a way that the effect of the second and the third auxiliary plane vectors (i.e., x1-y1, and x2-y2) are nullified. To achieve the maximum output voltage gain and to ensure that no reactive power is drawn from the utility supply, the input side power factor is maintained at unity. Nevertheless, the source side power factor is controllable. The modulation technique is implemented in dSPACE working in conjunction with a FPGA. Hardware results that validate the proposed control algorithm are discussed.
Filizadeh, S.,Safavian, L.S.,Emadi, A. The Korean Institute of Power Electronics 2002 JOURNAL OF POWER ELECTRONICS Vol.2 No.4
In this paper, two approaches for designing tracking controllers for a variable reluctance motor (VRM), namely the Lyapunov-based fuzzy approach and the classical approach, are compared. The nonlinear model of a VRM is first addressed. The two control schemes are introduced afterwards, and then applied to obtain tracking controllers. Simulation results of a sample case, to which the methods are applied, are also presented. Comparison of the methods based on the results obtained concludes the paper.