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Fast detection of open-switch faults with reduced sensor count for a fault-tolerant three-phase converter
, Article 2011 2nd Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2011 ; 2011 , Pages 546-550 ; 9781612844213 (ISBN) ; Zolghadri, M ; Poure, P ; Saadate, S ; Sharif University of Technology
Abstract
Fast fault detection and reconfiguration is necessary in power electronic converters in lots of applications to prevent further damage and to make possible the continuity of service. In this paper a very fast fault detection scheme is presented that minimizes the use of voltage sensors. A fault tolerant topology is studied. Control and fault detection system are implemented on a single FPGA and hardware in the loop experiments are performed to evaluate the detection scheme, the digital controller and the structure
AC voltage regulator based on AC/AC buck converter
, Article 7th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2016, 16 February 2016 through 18 February 2016 ; 2016 , Pages 140-146 ; 9781509003754 (ISBN) ; Mokhtari, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
This paper introduces a high efficiency AC voltage regulator based on an AC/AC buck converter cascaded by a transformer in series with the input voltage. The AC/AC converter uses an overlap time in the gate signals to solve the commutation problem. Non-use of any snubber circuits and current sensors leads to lower cost, smaller size and simpler hardware. The converter generates only the compensation term which results in smaller switches and, thus, lower cost. Simulation and experimental results verify the performance of the proposed topology
Three-phase PFC rectifier with high efficiency and low cost for small PM synchronous wind generators
, Article 7th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2016, 16 February 2016 through 18 February 2016 ; 2016 , Pages 302-307 ; 9781509003754 (ISBN) ; Tahami, F ; Valipour, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Small Permanent Magnet Synchronous Generators (PMSG's) are widely used in low power wind turbines. In order to inject the electrical power, generated by PMSG, to the grid, a back-To-back AC/AC power electronic converter is required. In this paper, a novel low cost efficient AC/DC converter is proposed for rectifier stage to obtain the maximum power per ampere of PMSG by using Power Factor Correction method. The new structure is based on DCM SEPIC converter. Reducing the number of semi-conductor switches has decreased converter cost. Additionally, other advantages of this Converter are employing easy control method to obtain the maximum power per ampere and using Synchronous inductance of...
Self-Powered soil moisture monitoring sensor using a picoampere quiescent current wake-up circuit
, Article IEEE Transactions on Instrumentation and Measurement ; Volume 69, Issue 9 , 2020 , Pages 6613-6620 ; Habibi, M ; Magierowski, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Low-power wireless stand-alone sensors that can operate without any wiring have received significant attention in sensor network applications. These devices harvest environmental energy resources to supply their power and transfer their collected data using wireless RF links. In many instances, the power supplied from the environment is far less than the power required by the sensor device. In this case, the main solution is to accumulate energy on a storage element, and when enough energy is stored, the sensor node is instantaneously activated using an undervoltage lockout (UVLO) circuit. During this short time burst, the sensor performs the required acquisition, transmits the results, and...
A secure and low-energy logic style using charge recovery approach
, Article ISLPED'08: 13th ACM/IEEE International Symposium on Low Power Electronics and Design, Bangalore, 11 August 2008 through 13 August 2008 ; 2008 , Pages 259-264 ; 15334678 (ISSN); 9781605581095 (ISBN) ; Moradi, A ; Ejlali, A ; Manzuri Shalmani, M. T ; Salmasizadeh, M ; Sharif University of Technology
2008
Abstract
The charge recovery logic families have been designed several years ago not in order to eliminate the side-channel leakage but to reduce the power consumption. However, in this article we present a new charge recovery logic style not only to gain high energy efficiency but also to achieve the resistance against side-channel attacks especially against differential power analysis attacks. Our approach is a modified version of a classical charge recovery logic style namely 2N-2N2P. Simulation results show a significant improvement in DPA-resistance level as well as in power consumption reduction in comparison with 2N-2N2P and other DPA-resistant logic styles. Copyright 2008 ACM
Design and Implementation of FPGA Based Real Time Simulator for Power Electronic Converters
, M.Sc. Thesis Sharif University of Technology ; Zolghadri, Mohammad Reza (Supervisor)
Abstract
Real-time Simulator plays an important role in the test of power electronic converters. Using of this simulators and Hardware-in-the-loop tests, cost and time of experiments will redused, furthermore those experiments which are not operative on the real system, can be achived. However, the accuracy of the used model in simulation as well as fast and easy programming of these simulators is very important. Therefore in this thesis, design and implementation of real-time simulator for power electronic converters have been discussed that in addition to high accuracy of the simulation, implementation of the several tests will be easy. As regards the power electronic switch is the most important...
Control of a microgrid with unbalanced loads using virtual negative-sequence impedance loop
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2014 , p. 78-83 ; Karimi, H ; Mokhtari, H ; Mahseredjian, J ; Sharif University of Technology
Abstract
This paper presents an effective control strategy for autonomous operation of a multi-bus medium voltage (MV) microgrid (MG) consisting of several dispatchable distributed generation (DG) units. Each electronically-coupled DG unit supplies the loads which can be unbalanced due to the inclusion of single-phase loads. The proportional resonance (PR) and droop controllers are, respectively, used to regulate the load voltage and share the average powers among the DG units. The virtual negative-sequence impedance controller (VNSIC) is proposed to effectively compensate the negative-sequence currents of the unbalanced loads. Moreover, the VNSIC minimizes the negative-sequence currents in the MV...
An adaptive droop control method for low voltage DC microgrids
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; December , 2014 , p. 84-89 ; Ashourloo, M ; Mokhtari, H ; Sharif University of technology
Abstract
DC microgrids (MGs) are becoming popular as effective means to integrate different energy resources. Conventionally, the droop control is adopted as a decentralized control method for power sharing in DC MGs. However, current sharing accuracy or voltage regulation deteriorates due to the effects of line impedances. In this paper, a new adaptive control strategy is proposed for DC MGs. In low load conditions, the output currents of the DGs are far from their maximum acceptable limits. Therefore, current sharing accuracy is not important. As load increases, the output currents of the DGs approach their maximum acceptable limits. Therefore, at high load conditions, accurate current sharing is...
Speed control of servo drives with a flexible couplings using fractional order state feedback
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2014 , p. 25-30 ; Moghadam, B. E ; Sharif University of Technology
Abstract
Using elastic couplings in servo motor drives may lead to torsional oscillations which are usually extinguished by reducing the bandwidth of the control system as a countermeasure. A high performance servo drive however needs fast dynamic characteristics. The conventional controllers, such as PI controllers, may not be able to improve the dynamic response while keeping the system stable. Fractional order modeling offers a good framework for flexible structures such as two mass servo drives. In this paper, the dynamic response and stability of two-mass servo drive is improved using a fractional order controller. The fractional order controller allows increasing the phase margin of the system...
Analysis of Phase-Shifted Full-Bridge Based dc-dc Converter considering transformer parasitic elements in discontinuous current mode
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2014 , p. 366-372 ; Karimi, Y ; Kaboli, S ; Sharif University of Technology
Abstract
In high-voltage applications, due to the use of high-ratio step-up transformers, the value of parasitic capacitance of these transformers is large compared to the low-voltage transformers. Moreover In these applications it is prefered to use single-capacitor filters instead of filters with inductors. In this paper a simple electrical model for two-winding high frequency transformer considering all of the parasitic elements is presented. This model is used in a full-bridge based dc-dc converter with capacitive output filter controlled by phase-shifted method. The operation of this converter in DCM is analysed and its analytical relations in different time intervals is derived and confirmed by...
Fault tolerant operation of single-ended non-isolated DC-DC converters under open and short-circuit switch faults
, Article 2013 15th European Conference on Power Electronics and Applications, EPE 2013 ; 2013 ; ISBN: 9781479901166 ; Shahbazi, M ; Poure, P ; Gholipour, E ; Saadate, S ; Sharif University of Technology
2013
Abstract
Fault tolerant operation of single-ended non-isolated DC-DC converters used in embedded and safety critical applications is mandatory to guaranty service continuity. This paper proposes a new, fast and efficient FPGA-based open and short-circuit switch fault diagnosis asssociated to fault tolerant converter topology. The results of Hardware-In-the-Loop and experimental tests are presented and discussed
A compact versatile microbial fuel cell from paper
, Article ASME 2013 11th Int. Conf. on Fuel Cell Science, Eng. and Technology Collocated with the ASME 2013 Heat Transfer Summer Conf. and the ASME 2013 7th Int. Conf. on Energy Sustainability, FUELCELL 2013 ; 2013 ; 9780791855522 (ISBN) ; Hashemi, N ; Hashemi, N ; Sharif University of Technology
2013
Abstract
Microbial fuel cells (MFCs) have been a potential green energy source for a long time but one of the problems is that either the technology must be used on a large scale or special equipment have been necessary to keep the fuel cells running such as syringe pumps. Paper-based microbial fuel cells do not need to have a syringe pump to run and can run entirely by themselves when placed in contact with the fluids that are necessary for it to run. Paper-based microbial fuel cells are also more compact than traditional MFCs since the device doesn't need any external equipment to run. The goal of this paper is to develop a microbial fuel cell that does not require a syringe pump to function. This...
Efficiency improvement of a high step up high efficiency converter for photovoltaic applications based on three-state switching cell
, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 454-458 ; 9781467344845 (ISBN) ; Zolghadri, M. R ; Hajimoradi, M. R ; Sharif University of Technology
2013
Abstract
This paper suggests methods for improving efficiency of a high step up high efficiency converter based on three state commutation cells. A loss analysis has been performed to identify the source of power loss. Based on this analysis, methods are presented to reduce losses in the most power dissipating elements. These methods include replacing some power diodes with large conduction losses with MOSFETs having small on-state resistance. Efficiency improvement up to %1.25 percent is verified in simulation and experimental results
Primary and secondary frequency control in an autonomous microgrid supported by a load-shedding strategy
, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 282-287 ; 9781467344845 (ISBN) ; Ameli, M. T ; Hamzeh, M ; Sharif University of Technology
2013
Abstract
This paper proposes a frequency control strategy for an islanded inverter-based microgrid which based on the priority of supply, has got two distinct types of loads, namely sensitive and deferrable. The proposed strategy consists of primary and secondary levels of generation control supported by a loadshedding scheme. The primary control regulates the output power of the distributed generator (DG) units to be proportional to their ratings while secondary control has got the duty of frequency restoration after each load change. Functionality of these two levels is demonstrated to be independent of each other. Both controls are in distributed forms which have no need of communication...
A new algorithm for optimal measurement placement, observability analysis and harmonic state estimation in power systems
, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 518-523 ; 9781467344845 (ISBN) ; Mokhtari, H ; Karimi, H ; Sharif University of Technology
2013
Abstract
Harmonic State Estimation (HSE) is a technique for identifying harmonic distributions in power systems with limited measurements. The main problem in HSE is the optimal placement of measurement meters such that the estimation error is minimized, while making the system fully observable. The second issue is the HSE method. This method must be accurate and fast enough in order to have an accurate HSE. This paper presents a new algorithm that uses minimum variance criterion (MVC) and a sequential method for optimal meters placement, SVD method for observability analysis and finally WLS method for harmonic estimation. The proposed method minimizes the number of measurement devices and the error...
Stabilization of DC microgrids with constant-power loads by an active damping method
, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 471-475 ; 9781467344845 (ISBN) ; Khorsandi, A ; Mokhtari, H ; Sharif University of Technology
2013
Abstract
High penetration of constant-power loads (CPL) in dc microgrids may cause a destabilizing effect on the system that can lead to severe voltage oscillations. This paper addresses stability problems of the CPLs and proposes a simple active damping technique to damp the oscillations caused by CPLs. The particle swarm optimization algorithm has been used to find the best values of the parameters of the proposed active damper to achieve maximum damping of the oscillations. The effectiveness of the proposed approach is verified by simulations
Using frequency coupling matrix for estimation of distribution network losses
, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conferenc ; 2013 , Pages 344-348 ; 9781467344845 (ISBN) ; Najmi, V ; Mokhtari, H ; Sharif University of Technology
2013
Abstract
Harmonic producing loads, which are increasingly used in industries, cause power quality problems as well as increase in system losses. To deal with the problems associated with harmonics and to reduce their effects on power networks, study of the effects of non-linear loads on distribution networks is essential. In this paper, the non-linear loads of residential consumers are modeled and simulated. A typical residential consumer and a simplified short feeder are simulated in order to make an estimation of the power and energy losses and their corresponding costs. The simulations are verified using practical measurements from real customers. ©2013 IEEE
New strategy for optimization of output power of a DFIG wind turbine
, Article International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2011 and Electromotion 2011 Joint Conference ; Sept , 2013 , Pages 69-72 ; 9781467350037 (ISBN) ; Ehsan, M ; Afsharirad, H ; Nazaraliloo, M ; Sharif University of Technology
2013
Abstract
This paper presents a method to maximize the output power of a DFIG wind turbine. In this method, an optimization technique based on mathematical analysis has been used. The modeling of DFIG is performed using MATLAB. To evaluate the maximum output power of a DFIG, detailed expressions for output power and losses are derived as functions of generator slip, the magnitude and phase angle of rotor excitation voltage in various wind velocities. The outcomes of this method demonstrate that maximum output power of a DFIG wind turbine do not happen in the maximum input power (the mechanical power of wind turbine)
Effects of wind turbines on voltage profile
, Article International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2011 and Electromotion 2011 Joint Conference ; Sept , 2013 , Pages 64-68 ; 9781467350037 (ISBN) ; Ehsan, M ; Afsharirad, H ; Nazaraliloo, M ; Sharif University of Technology
2013
Abstract
For distribution grids connected wind power generation, voltage quality is an important issue for the system planning purpose. The operation of wind turbines in the distribution networks may affect the voltage quality offered to the consumers. One of the most important considerations is the effect on the voltage profile, i.e. the induced slow voltage variations, which are the subject of this paper. The wind turbines can be operated in two modes: constant-speed and variable-speed. Each one of these cases has different impact on steady state voltage of distribution grids. For evaluation of these impacts, we have simulated SCIG generator that works in constant-speed operation and DFIG generator...
An MPC method based on a hybrid model of a three-phase inverter with output LC- filter
, Article 2012 3rd Power Electronics and Drive Systems Technology, PEDSTC 2012, 15 February 2012 through 16 February 2012 ; February , 2012 , Pages 170-174 ; 9781467301114 (ISBN) ; Mokhtari, H ; Sharif University of Technology
2012
Abstract
Controlling inverters with LC output filters in order to achieve a high quality desired output voltage or current is a challenging problem in power electronics. The LC filter and the binary nature of switch state variables increase the difficulty of achieving a single comprehensive model for the system. In this paper, a hybrid model is presented for a three-phase inverter with an LC output filter and a three-phase RL load. Then, the Model Predictive Control (MPC) algorithm is applied to the model and a geometrical approximate method is used to fit the answers to the binary values. Simulation results for a sample system verify the usability of the method and the quality of the answers