Search for: power-converters
Total 80 records
M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad
Nowadays, despite the special position of power electronic converters in the world, and the fact that they become an integral part of human life, still in the wake of a serious necessity the development process has not stopped and the increasingly fast pace, it opens up new horizons. This important necessity emerges from the environmental concerns regarding consumption of fossil fuels and their limited and imbalanced distribution which can be effectively addressed with the use renewable energy systems. By improving the quality of the semiconductor switches and offering new topologies in different functions as well as using new control methods, scholars try to develop enhanced converters in...
Article 6th Annual International Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2015, 3 February 2015 through 4 February 2015 ; February , 2015 , Pages 247-252 ; 9781479976539 (ISBN) ; Zolghadri, M. R ; Noroozi, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2015
In this paper a novel T type scheme for 1-phase direct ac/ac converters is proposed. In this topology, frequency changing takes place directly (without common DC voltage bus) through three converters that are connected in a T structure. Unity power factor and precise output voltage regulation is achieved through appropriate control of these three converters. H-bridge converters are implemented, as the basic unit, in each branches of T to make the proposed converter. The converter is controlled such that the average active power of each H-bridges remains zero. So capacitors are implemented in DC links of H-bridges. In comparison to conventional back-to-back converters, life time of each...
Article IET Power Electronics ; Volume 10, Issue 7 , 2017 , Pages 802-807 ; 17554535 (ISSN) ; Mokhtari, H ; Sharif University of Technology
The commutation issue is the most important limiting factor of expanding AC chopper applications, which in most cases are solved by employing snubber circuits, implementing sensor-based selective switching patterns and utilising resonant circuits. To overcome the commutation problem, this study proposes a novel non-resonant AC/AC buck converter with no snubber circuits and no sensor-based switching patterns. The introduced hardware configuration and the proposed control strategy provide a path for an inductive load current in all switching states. This converter offers higher reliability and efficiency as well as lower cost compared to the AC choppers with snubber circuits or voltage and...
Article 2006 1st IEEE Conference on Industrial Electronics and Applications, ICIEA 2006, Singapore, 24 May 2006 through 26 May 2006 ; 2006 ; 078039514X (ISBN); 9780780395145 (ISBN) ; Zolghadri, M. R ; Walters, M ; Homaifar, A ; Sharif University of Technology
Paralleling power modules is designed to share system loads (stresses) equally to improve system reliability. Due to variations in the parameters in the power converter system, temperature mismatches may occur. These mismatches may lead to unequal life expectancy of individual converters in the total system. It is believed that equalizing the operating temperature of the semiconductor devices may improve total system reliability. In this paper a new thermal-based load-sharing scheme for parallel converters is proposed. In this scheme, the load current is redistributed among parallel converters based on the temperature of the converters. The main goal is to minimize the relative temperature...
An isolated bidirectional integrated plug-in hybrid electric vehicle battery charger with resonant converters, Article Electric Power Components and Systems ; Volume 44, Issue 12 , 2016 , Pages 1371-1383 ; 15325008 (ISSN) ; Akbari, R ; Tahami, F ; Oraee, H ; Sharif University of Technology
Taylor and Francis Inc 2016
Plug-in hybrid electric vehicles draw electricity from the electrical grid and store energy in their batteries. To increase charge availability for plug-in hybrid electric vehicles, on-board chargers can be used, which should be small in size and lightweight. In this article, an on-board bidirectional soft-switched battery charger is proposed that utilizes a phase-shift-controlled dual-bridge series resonant converter with isolation. The bidirectional characteristic of proposed charger makes it suitable for vehicle-to-grid operation (i.e., injecting power from the vehicle to the grid) in smart grids. A switching control scheme is also proposed to provide soft-switching operation for all...
Article 2012 3rd Power Electronics and Drive Systems Technology, PEDSTC 2012, 15 February 2012 through 16 February 2012 ; February , 2012 , Pages 98-102 ; 9781467301114 (ISBN) ; Ebrahimi, S ; Oraee, H ; Sharif University of Technology
Improvement in switching techniques is one of the effective methods for increasing the voltage quality in Multilevel Inverters. In this paper, a novel switching technique using frequency modulation is proposed to achieve high quality output voltage of multilevel inverters. This method is employed to different configurations of multilevel inverters consist of Diode Clamped (or Neutral Point Clamped), Flying Capacitor and Cascaded H-bridge. Each multilevel inverter which utilizes this technique is modeled and simulated to investigate the performance of this method by the help of MATLAB/Simulink software. The Results show that this innovative method considerably reduces total harmonic...
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
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...
Article IEEE Transactions on Power Electronics ; Volume 32, Issue 10 , 2017 , Pages 8089-8099 ; 08858993 (ISSN) ; Davari, P ; Mokhtari, H ; Loh, P. C ; Blaabjerg, F ; Sharif University of Technology
In a classical ac microgrid (MG), a common frequency exists for coordinating active power sharing among droop-controlled sources. Like the frequency-droop method, a voltage-based droop approach has been employed to control the converters in low voltage direct current (LVDC) MGs. However, voltage variation due to the droop gains and line resistances causes poor power sharing and voltage regulation in dc MG, which in most cases are solved by a secondary controller by using a communication network. To avoid such an infrastructure and its accompanied complications, this paper proposes a new droop scheme to control dc sources by introducing a small ac voltage superimposed onto the output dc...
RCD snubber design based on reliability consideration: A case study for thermal balancing in power electronic converters, Article Microelectronics Reliability ; Volume 88-90 , 2018 , Pages 1311-1315 ; 00262714 (ISSN) ; Zarghani, M ; Kaboli, S ; Sharif University of Technology
Elsevier Ltd 2018
In a turn-off RCD snubber, the capacitor value is usually optimized in order to minimize the power dissipated in the switch and snubber circuit. However, it may not be the best value of the snubber capacitor from the reliability point of view. In this paper, the capacitor value is optimized based on reliability considerations. Proposed method presents a new design to achieve the maximum reliability for the set of switch and its snubber. Mathematical analysis of the proposed method is conducted in MATLAB environment. Also, the experimental results are presented for validity of the theoretical analysis. © 2018 Elsevier Ltd
Article IEEE Transactions on Power Delivery ; Volume 23, Issue 2 , 2008 , Pages 1191-1199 ; 08858977 (ISSN) ; Kazemi, A ; Fotuhi Firuzabad, M ; Edris, A. A ; Sharif University of Technology
The impact of an interline power-flow controller (IPFC) on composite system delivery point and overall system reliability indices is examined in this paper. In this application, the IPFC with dc transmission lines is employed in a system for coordinated control of line impedances of two, distance away, transmission lines with the objective of managing power flows on the two lines. It is also used to balance the real power being transferred between the compensated lines. For this purpose, the reliability model associated with a converter station has been developed and incorporated in an IPFC reliability model. A number of reliability indices are calculated at both the loadpoint and system...
Application of random PWM technique for reducing the conducted electromagnetic emissions in active filters, Article IEEE Transactions on Industrial Electronics ; Volume 54, Issue 4 , 2007 , Pages 2333-2343 ; 02780046 (ISSN) ; Mahdavi, J ; Agah, A ; Sharif University of Technology
A pulsewidth modulation (PWM)-controlled active filter generates harmonics at the switching frequency and its multiples in the RF range, and the concentrated power spectrum may produce electromagnetic interference (EMI) problems. In this paper, the random PWM (RPWM) technique is applied in order to spread the noise spectrum over a wide range, thus, considerably reducing the amplitudes of these harmonics and the consequent EMI problems. To study the operation of active filters, the case of an ac/dc converter along with a power-factor corrector is considered as a nonlinear load and a series active filter, respectively. A line impedance stabilization network is used to study the RF noise...
Article 2006 IEEE Power Engineering Society General Meeting, PES, Montreal, QC, 18 June 2006 through 22 June 2006 ; 2006 ; 1424404932 (ISBN); 9781424404933 (ISBN) ; Karimi Ghartemani, M ; Sharif University of Technology
IEEE Computer Society 2006
This paper presents a power flow controller for a matrix converter as the power electronic interface between a high-speed micro-turbine generator and a utility distribution system. The matrix converter converts the high-frequency of a micro-turbine generator to a conventional frequency of the utility system, based on a novel switching strategy. The controller regulates magnitude and phase-angle of the converter output voltage to accommodate real and reactive power flow requirements of the utility system. Performance of the matrix converter based microturbine generation system including the power flow controller is evaluated based on digital time-domain simulation studies in the PSCAD/EMTDC...
Article International Symposium on Industrial Electronics 2006, ISIE 2006, Montreal, QC, 9 July 2006 through 13 July 2006 ; Volume 2 , 2006 , Pages 1486-1491 ; 1424404975 (ISBN); 9781424404971 (ISBN) ; Kaboli, S ; Mahdavi, J ; Sharif University of Technology
This paper is a summary and in-depth evaluation of some popular models for power electronic converters. Proper examples are given to support the evaluation with a complete comparison between the actual and simulated results. The paper presents the effort behind the design and analysis of DC-DC Converters and discuses their features. Some advantages and disadvantages of the studied models and the complicities of the nonlinear structure of the switching function of the converters are explained here. The paper offers some useful criteria for future selection and development on different DC-DC Converters. © 2006 IEEE
Integrated bidirectional isolated soft-switched battery charger for vehicle-to-grid technology using 4-Switch 3Φ-rectifier, Article IECON Proceedings (Industrial Electronics Conference) ; November , 2013 , Pages 906-911 ; 9781479902248 (ISBN) ; Taghavi, M ; Tahami, F ; Oraee, H ; Sharif University of Technology
Battery and plug-in hybrid vehicles equipped with bidirectional battery chargers are capable of supplying power to the electric grid according to power system demand. This technology is called 'vehicle to grid' or V2G. A bidirectional on-board charger can be used to improve the charge availability. An on-board charger should have small size and light weight. On the other hand, the charger must minimize power quality impact, draw current at high power factor to maximize power from an outlet. In this paper, a new three-phase integrated bidirectional isolated soft-switched battery charger is proposed which is appropriate for vehicle to grid technology. The charger utilizes a 4-switch...
Open-and short-circuit switch fault diagnosis for nonisolated DC-DC converters using field programmable gate array, Article IEEE Transactions on Industrial Electronics ; Volume 60, Issue 9 , October , 2013 , Pages 4136-4146 ; 02780046 (ISSN) ; Jamshidpour, E ; Poure, P ; Saadate, S ; Zolghadri, M. R ; Sharif University of Technology
Fault detection (FD) in power electronic converters is necessary in embedded and safety critical applications to prevent further damage. Fast FD is a mandatory step in order to make a suitable response to a fault in one of the semiconductor devices. The aim of this study is to present a fast yet robust method for fault diagnosis in nonisolated dc-dc converters. FD is based on time and current criteria which observe the slope of the inductor current over the time. It is realized by using a hybrid structure via coordinated operation of two FD subsystems that work in parallel. No additional sensors, which increase system cost and reduce reliability, are required for this detection method. For...
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
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
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...
Article 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe, 3 September 2019 through 5 September 2019 ; 2019 ; 9789075815313 (ISBN) ; Davari, P ; F. Firuzabad, M ; Blaabjerg, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2019
Power electronics is becoming an underpinning technology for modern power systems. Power converters are increasingly used in various applications implying different levels of importance in power systems. Hence, optimal decision-making for manufacturing, control, operation and maintenance of them requires understanding of their importance in the power systems. Furthermore, identifying the converters importance may be beneficial for simplifying the system-level reliability modeling in a large Power Electronic based Power Systems (PEPSs). Thereby, a Failure Mode, Effects and Criticality Analysis (FMECA) approach is proposed in this paper in order to figure out the importance of converters in...
Article IET Electric Power Applications ; Volume 7, Issue 2 , 2013 , Pages 106-115 ; 17518660 (ISSN) ; Jandaghi, B ; Oraee, H ; Sharif University of Technology
Brushless Doubly-Fed Induction Generator has attractive features to be the first choice in next generation of wind generators. However, its efficiency and power-to-weight ratio are slightly lower in comparison to induction machine with the same rating. Considerable part of these imperfections arises from the rotor design, which produces magnetic field with considerable undesirable spatial harmonics. This paper proposes a novel rotor configuration to reduce spatial harmonic distortion of air-gap magnetic field as well as improving some drawbacks of the conventional structure, including unequal magnitudes of rotor bar currents, teeth saturation at low average air gap magnetic fields, high core...
Article 6th Annual International Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2015, 3 February 2015 through 4 February 2015 ; 2015 , Pages 430-435 ; 9781479976539 (ISBN) ; Fotuhi Firouzabad, M ; Rezazadeh, G ; Zolghadri, M. R ; Sharif University of Technology
One of the most significant parameters that the electronic designers are trying to increase, is the reliability or the effective lifetime of the circuit. For example the designers are always trying to achieve higher efficiency. One of the most important influence of the greater efficiency is the reduction of the thermal stress on the components, that leads to increase of the reliability. In this paper the reliability of two different industry-based structures as an AC/DC converter, have been compared. These circuits are from two different generations of power supplies in a particular industry, which the first introduced structure has greater efficiency due to soft switching. FIDES method has...