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Frozen leg operation of a three-phase dual active bridge DC/DC converter at light loads
, Article Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC ; Volume 2018-March , 18 April , 2018 , Pages 3385-3391 ; 9781538611807 (ISBN) ; Blaabjerg, F ; Yazdani, F ; Bahman, A. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
A three-phase dual active bridge (DAB) converter is designed and constructed as the DC/DC stage of a 50 kW fast charger station. Recently introduced 300A SiC power modules and drivers are utilized in the converter to obtain a high efficiency. Each module has two interconnected switches with anti-parallel diodes resembling a converter leg. It is observed that the driver halts the module operation as a result of protective actions such as over-current, gate under-voltage, or gate overvoltage. In such case the module operates as a leg with two diodes until an external hardware signal resets the driver. The aim of this paper is to provide analysis, simulation and experiments for a three-phase...
Numerical model for estimation of corrosion location in nuclear power plant steam generators
, Article Nuclear Engineering and Design ; Volume 241, Issue 1 , 2011 , Pages 95-100 ; 00295493 (ISSN) ; Jahanfarnia, G ; Kebriaee, A ; Sharif University of Technology
Abstract
Deposition of dissolved impurities and corrosion in steam generators is a significant problem in the operation of nuclear power plants. Impurities and corrosion products usually accumulate in the secondary sides of steam generators (SG) and form deposits on the SG surfaces. A high level of impurity concentration close to the SG heating surface causes the corrosion process to occur with more intensity. The aim of this study is to estimate the most probable locations of impurity concentration and deposition in a SG. Equations representing the convection and diffusion in the liquid phase close to the heated surface (the viscous sub layer) are derived. Based on the mass balance of impurities in...
Mitigating ferroresonance in coupling capacitor voltage transformers with ferroresonance suppressing circuits
, Article IEEE EUROCON 2009, EUROCON 2009, St. Petersburg, 18 May 2009 through 23 May 2009 ; 2009 , Pages 817-822 ; 9781424438617 (ISBN) ; Babazadeh, D ; Esmaeilnia Shirvani, R ; Purrezagholi, M ; Sharif University of Technology
2009
Abstract
In order to restrain ferroresonance in coupling capacitor voltage transformers (CCVT), two kinds of ferroresonance suppression circuits (FSCs) , are proposed in this paper: the resonant type, the fastsaturation reactor type which are connected to secondary side of CCVTs. Frequency domain analyses, for voltage ratio magnitude, are carried out for CCVTs to obtain preferable FSC. Furthermore, using surge suppressors such as metal oxide varistors (MOV) to improve the performance of the FSCs is investigated. Time domain simulations demonstrate that ferroresonance can be cleared in few cycles in presence of FSCs. The Electromagnetic Transients Program (EMTP) is used for modeling and fine-tuning...
Designing an adjustable wide range regulated current source
, Article IEEE Transactions on Power Electronics ; Volume 25, Issue 1 , 2010 , Pages 197-208 ; 08858993 (ISSN) ; Rashidian, B ; Zolghadri, M. R ; Alavi, S. M. H ; Sharif University of Technology
Abstract
LLC resonant converter has been used widely as dc-dc converter for achieving constant dc voltage. In this paper, an LLC resonant converter, by adding an inductance to its conventional topology and considering the rectifying stage stray inductances, is proposed for an adjustable wide range regulated current source (20-200 A dc) for using as ion implanter's filament power supply. The additional inductor increases output current adjustment range and efficiency, especially at light loads. Transformer's leakage inductances and rectifying stage stray inductances have been considered. Because of these inductances, the rectifier stage always works in continuous conduction mode, and its conduction...