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voltage-controllers
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Total 130 records
Design & Implementation of Frequency Synthesizer for Multi-Band Standard Transceivers
, Ph.D. Dissertation Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
Nowadays, general electronic devices such as computers, notebooks, cellular phones and etc. are supporting Bluetooth, RFID and Zigbee standards. By integrating all of RF sections of mentioned standards, total power consumption, occupied area and total cost and price will be decreased. RF devices communications with maximum bandwidth and data rate with minimum power consumption are the main purposes in designing RF and digital building blocks. Bluetooth and Zigbee standards are applied for networking the desired RF devices. RFID standard is providing automatic identifications, item tracking and tracing, item management and inventory. RFID standard makes the communication between Tags and...
Clock and Data Recovery Circuit For High Speed Serial Communication
, M.Sc. Thesis Sharif University of Technology ; Hajsadeghi, Khosroo (Supervisor)
Abstract
In this thesis, A novel approach for ¼-rate clock Phase Detector (PD) structure for Phase Locked Loop (PLL)-based Clock and Data Recovery (CDR) is proposed. In this approach, the retimed data is generated within the circuit and no extra circuit is needed. Another advantage of this topology is that the error and reference signals are independent of delay time through gates and no extra replica circuit is needed to compensate the delay. This topology results in a lower power circuit and smaller area for high speed application compared to conventional topologies
Power System Voltage Improvement through Coordinationg Reactive Power Resources on a Smart Grid Framework
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehrani Fard, Ali (Supervisor)
Abstract
With the increasing penetration of renewable energies as distributed generation (DG) in power systems, technical problems arise in both distribution and transmission system level. Voltage rise is the main barrier for connection of DGs in rural areas, while excessive reactive power demand from transmission system is the major concern for Transmission System Operators (TSO). Here, a centralized control scheme based on the Smart Grid is proposed to reduce the impact on the transmission system voltages and improve its stability, while mitigating the voltage rise issue in the distribution network. Reactive power output of DGs, substation capacitors and tap setting of transmission transformer are...
Global Control of Hybrid Microgrids Using MIMO Control
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
Given the growing advantage of exploiting renewable energy resources over fossil fuels and using distributed generation systems, microgrids seem to be the best solution for reaching the energy-efficient world of the future. Hybrid microgrids are the best options among all other types of microgrids because they make it possible to use AC and DC sources and loads together and at the same time. Since connecting AC and DC sections of a hybrid microgrid leads to the interaction between them, proper control of interlinking converter(s) is crucial for the reliable and stable operation of the entire microgrid. In this study, small signal model of a hybrid AC/DC microgrid consisting of static and...
Corrective voltage control scheme considering demand response and stochastic wind power
, Article IEEE Transactions on Power Systems ; Vol. 29, issue. 6 , 2014 , pp. 2965-2973 ; ISSN: 08858950 ; Soroudi, A ; Mohammadi-Ivatloo, B ; Parniani, M ; Sharif University of Technology
Abstract
This paper proposes a new approach for corrective voltage control (CVC) of power systems in presence of uncertain wind power generation and demand values. The CVC framework deals with the condition that a power system encounters voltage instability as a result of severe contingencies. The uncertainty of wind power generation and demand values is handled using a scenario-based modeling approach. One of the features of the proposed methodology is to consider participation of demand-side resources as an effective control facility that reduces control costs. Active and reactive redispatch of generating units and involuntary load curtailment are employed along with the voluntary demand-side...
Analyzing and modeling of a new resonance inverter for low power vehicular application
, Article PECon 2012 - 2012 IEEE International Conference on Power and Energy ; 2012 , Pages 576-581 ; 9781467350198 (ISBN) ; Keipour, A ; Sudi, Z ; Moallemi, M ; Hajihosseinlu, A ; Sharif University of Technology
2012
Abstract
In this paper we proposed a novel inverter to convert a DC voltage to a desired AC voltage. This inverter is designed for variable inductive loads and low output power applications. We proposed a novel simple PWM method which enables the inverter to keep the output current at six times more than the rated output current, without reducing output voltage value. In addition, based on a simple use of resonance in the circuit, the new inverter can raise the output voltage to extremely high amplitude for a relatively short time. These characteristics make the proposed inverter is useful for some industrial applications such as electrical vehicle. The new configuration of the circuit consists of a...
Probabilistic determination of pilot points for zonal voltage control
, Article IET Generation, Transmission and Distribution ; Volume 6, Issue 1 , January , 2012 , Pages 1-10 ; 17518687 (ISSN) ; Soroudi, A ; Ranjbar, A. M ; Sharif University of Technology
Abstract
Owing to the local nature of voltage and reactive power control, the voltage control is managed in a zonal or regional basis. A new comprehensive scheme for optimal selection of pilot points is proposed in this study. The uncertainties of operational and topological disturbances of the power system are included to provide the robustness of the pilot node set. To reduce the huge number of probable states (i.e. combined states of load and topological changes), a scenario reduction technique is used. The resulted optimal control problem is solved using a new immune-based genetic algorithm. The performance of the proposed method is verified over IEEE 118-bus and realistic Iranian 1274-bus...
Modeling and design of an oscillatory current-sharing control strategy in dc microgrids
, Article IEEE Transactions on Industrial Electronics ; Volume 62, Issue 11 , May , 2015 , Pages 6647-6657 ; 02780046 (ISSN) ; Ghazanfari, A ; Mohamed, Y. A. R. I ; Karimi, Y ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
This paper presents an effective control scheme in dc microgrids to precisely share the load current oscillatory and dc components among distributed generation (DG) units. The proposed control strategy includes current and voltage control blocks. The current control block consists of oscillatory and dc current-sharing units. The main idea of the proposed method is to share the load current oscillatory and dc components among the DG units based on their rated power, by assigning appropriate output impedance values and droop coefficients to each DG unit. The voltage control block is a multiloop voltage control unit employed to control the microgrid voltage. The detailed model of the proposed...
Fast fault detection method for modular multilevel converter semiconductor power switches
, Article IET Power Electronics ; Volume 9, Issue 2 , 2016 , Pages 165-174 ; 17554535 (ISSN) ; Khodabandeh, M ; Zolghadri, M. R ; Sharif University of Technology
Institution of Engineering and Technology
2016
Abstract
This study proposes a new fault detection method for modular multilevel converter (MMC) semiconductor power switches. While in common MMCs, the cells capacitor voltages are measured directly for control purposes, in this study voltage measurement point changes to the cell output terminal improving fault diagnosis ability. Based on this measurement reconfiguration, a novel fault detection algorithm is designed for MMCs semiconductor power switches. The open circuit and short circuit faults are detected based on unconformity between modules output voltage and switching signals. Simulation and experimental results confirm accurate and fast operation of the proposed method in faulty cell...
An adaptive pulse-width modulation for limited molecule production and storage
, Article 2018 Iran Workshop on Communication and Information Theory, IWCIT 2018, 25 April 2018 through 26 April 2018 ; 2018 , Pages 1-6 ; 9781538641491 (ISBN) ; Mirmohseni, M ; Nasiri Kenari, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
The nature of molecular transmitter imposes some limitations on the molecule production process and its storage. As these molecules act the role of the information carriers, their limitation affect the transmission process and the system performance considerably. In this paper, we focus on these limitations at the transmitter, the limited production rate and finite storage capacity. We consider a time-slotted communication where the transmitter opens its outlet and releases the stored molecules for a time duration to send bit '1' and remains silent to send bit '0'. By changing the duration molecules are released, we propose an adaptive pulse-width modulation. The objective is to find the...
Modeling of D-STATCOM in distribution systems load flow
, Article Journal of Zhejiang University: Science A ; Volume 8, Issue 10 , 2007 , Pages 1532-1542 ; 1673565X (ISSN) ; Shayanfar, H. A ; Fotuhi Firuzabad, M ; Sharif University of Technology
2007
Abstract
This paper presents modeling of Distribution STATCOM (D-STATCOM) in load flow calculations for the steady-state voltage compensation. An accurate model for D-STATCOM is derived to use in load flow calculations. The rating of this device as well as the direction of required reactive power injection for voltage compensation in the desired value (1 p.u.) is derived and discussed analytically and mathematically by the phasor diagram method. Furthermore, an efficient method for node and line identification used in load flow calculations is presented. The validity of the proposed model is examined by using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best...
An enhanced under-voltage load-shedding scheme to provide voltage stability
, Article Electric Power Systems Research ; Volume 77, Issue 8 , 2007 , Pages 1038-1046 ; 03787796 (ISSN) ; Ranjbar, A. M ; Mozafari, B ; Sadati, N ; Sharif University of Technology
2007
Abstract
Under-voltage load shedding is one of the most important tools for avoiding voltage instability. In this paper, an optimal load-shedding algorithm is developed. This approach is based on the concept of the static voltage stability margin and its sensitivity at the maximum loading point or the collapse point. The traditional load-shedding objective is extended to incorporate both technical and economic effects of load shedding. The voltage stability criterion is modeled directly into the load-shedding scheme. The proposed methodology is implemented over the IEEE 14 and 118 bus test systems and solved using a mathematical (GAMS/CONOPT) and two heuristic (PSO and GA) methods. The heuristic...
A conceptual structure for value based assessment of dynamic reactive power support in power markets
, Article Electric Power Systems Research ; Volume 77, Issue 7 , 2007 , Pages 761-770 ; 03787796 (ISSN) ; Vakilian, M ; Feuillet, R ; Hadj Said, N ; Sharif University of Technology
2007
Abstract
This paper presents a practical reactive power valuation method, for the purpose of the reactive power pricing, in which the VAr value is decomposed into two components. These components are basically different from those already employed in the literature. Using a security constrained optimization model, the proposed scheme allocates two specific amounts of MW transactions to each generator as a dynamic reactive power source. One of these allocated amounts represents the contribution of the VAr resource to the shipment of active power, while the other one represents the contribution to the protection of the system against voltage instability. The final VAr value is derived using the...
Using level restoring method for dual supply voltage
, Article 19th International Conference on VLSI Design held jointly with 5th International Conference on Embedded Systems Design, Hyderabad, 3 January 2006 through 7 January 2006 ; Volume 2006 , 2006 , Pages 601-605 ; 10639667 (ISSN) ; 0769525024 (ISBN); 9780769525020 (ISBN) ; Emadi, M ; Farbiz, F ; Sharif University of Technology
2006
Abstract
A new level converter for use in dual voltage SOI digital circuits is presented. This technique uses the idea of keeper transistors, and consumes less power compared to the traditional methods. The effects of load capacitance on the circuit are studied by extensive simulations. © 2006 IEEE
GA-based optimization of total harmonic current distortion and suppression of chosen harmonics in induction motors
, Article International Symposium on Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006, Taormina, 23 May 2006 through 26 May 2006 ; Volume 2006 , 2006 , Pages 1361-1366 ; 1424401941 (ISBN); 9781424401949 (ISBN) ; Aflaki, M ; Rezazade, A. R ; Sharif University of Technology
2006
Abstract
In this study, a genetic algorithm optimization technique is applied, to minimize the total harmonic current distortion (THCD) in induction motors fed by high power inverters, based on an approximate model. That is, having defined a desired fundamental output voltage, optimal pulse patterns (switching angles) are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for two cases of 3 and 5 switching instants in the first quarter period of PWM waveform are presented. In the sequel, considering that the torque pulsation is mainly affected by the presence of low-order harmonics, the fifth, seventh, 11th, and 13th order harmonics (in the case of 5...
Experimental investigation of on-demand ferrofluid droplet generation in microfluidics using a Pulse-Width Modulation magnetic field with proposed correlation
, Article Sensors and Actuators, B: Chemical ; Volume 329 , 2021 ; 09254005 (ISSN) ; Favakeh, A ; Alborzi, S ; Shafii, M. B ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Micro-magnetofluidics offers a promising tool to regulate the drop formation process with versatile applications in engineering and biomedicine. In the present study, on-demand ferrofluid drop generation at a T-junction is investigated utilizing a magnetic pulse. Also, a novel method for ferrofluid droplet formation is introduced using a non-uniform Pulse-Width Modulation (PWM) magnetic field. A novel mechanism of drop generation named “beating regime” was seen for the first time in which the ferrofluid moves back and forth before the breakup. The effect of the magnetic induction, continuous phase flow rate, duty cycle, and applied frequency on the generation frequency and drop diameter was...
A low voltage, high speed current mode sample and hold for high precision applications
, Article 2005 European Conference on Circuit Theory and Design, Cork, 28 August 2005 through 2 September 2005 ; Volume 1 , 2005 , Pages 269-272 ; 0780390660 (ISBN); 9780780390669 (ISBN) ; Bakhtiar, M. S ; Sharif University of Technology
2005
Abstract
This paper presents a zero-voltage switching current mode sample and hold(S/H) circuit. The proposed S/H has 12 bit linearity at 180MHz sampling rate for 1.5v supply voltage. The S/H circuit is designed for 0.18μm CMOS technology
On the performance of optimal flux search controller for DTC based induction motor drives
, Article 2005 IEEE International Conference on Electric Machines and Drives, San Antonio, TX, 15 May 2005 through 15 May 2005 ; 2005 , Pages 1752-1756 ; 0780389875 (ISBN); 9780780389878 (ISBN) ; Vahdati Khajeh, E ; Zolghadri, M. R ; Homaifar, A ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
Application of a flux search controller in direct torque control of induction motor drives produces divergence problem and steady state flux ripple, because of the disturbance in the control loop. In this paper, an investigation about the origin of this noise has been performed. It is shown that the variation of voltage harmonics is the main reason of disturbance in the flux control loop. The minimum allowable value of flux step has been determined based on this analysis to prevent the divergence problem. Feasibility of noise cancellation has been discussed. Experimental results are presented to justify the theoretical analysis. © 2005 IEEE
A reduced complexity 3 rd order digital delta-sigma modulator for fractional-N frequency synthesis
, Article Proceedings - 17th International Conference on VLSI Design, Concurrently with the 3rd International Conference on Embedded Systems Design, Mumbai, 5 January 2004 through 9 January 2004 ; Volume 17 , 2004 , Pages 615-618 ; 10639667 (ISSN) ; Atarodi, S. M ; Bornoosh, B ; Kusha, A. A ; Sharif University of Technology
2004
Abstract
A reduced complexity third-order digital delta-sigma modulator is presented. The modulator consists of two cascaded sections to produce proper shaping of quantization noise with minimum hardware. A new architecture for a digital third-order delta-sigma modulator based on Ritchie structure is proposed. The measurement results show 94dB SNR and 65% dynamic range
Application of neural networks and state space averaging to a DC/DC PWM converter in sliding mode operation
, Article IECON Proceedings (Industrial Electronics Conference) ; Volume 1 , 2000 , Pages 172-177 ; Nasiri, M. R ; Agah, A ; Sharif University of Technology
IEEE Computer Society
2000
Abstract
A novel output feedback neural controller is presented for the implementation of sliding mode control of DC/DC converters. The controller, which consists of a multilayer perceptron, has been trained so as to be robust for large variations of system parameters and state variables. Fast dynamic behavior is the other main advantage of the proposed controller, which allows realization of all the beneficial features of sliding mode control technique. Other advantages of the controller are simplicity and low cost. Computer simulations are carried out to investigate the effectiveness of the controller in voltage regulation for a relatively complex topology such as a Cuk converter. Simulation...