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Comparison of common-mode voltage in three-phase quasi-Z-source inverters using different shoot-through implementation methods
, Article Proceedings - 2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering, CPE-POWERENG 2018 ; 4 June , 2018 , Pages 1-6 ; 9781538625088 (ISBN) ; Zolghadri, M. R ; Yaghoubi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In Z-source family inverters, shoot-through (ST) states are applied as a part of passive state in each switching cycle. The distribution of ST intervals along a switching period affects the system parameters as total harmonic distortion (THD), switching loss and common-mode voltage (CMV). In this paper, ST methods in a three-phase quasi-Z-source inverter (q-ZSI) are compared due to the CMV level. High-frequency harmonics of CMV cause leakage current flow in a transformerless grid-connected photovoltaic (PV) system. Through the comparison of the ST methods, the method with minimum CMV is identified. The experimental results are Prasented for a low voltage q-ZSI prototype. © 2018 IEEE
A new method for solving nonhermitian perturbation theory for the microdisc resonators with phi-periodic refractive index
, Article Proceedings of SPIE- Silicon Photonics and Photonic Integrated Circuits, Strasbourg, 7 April 2008 through 10 April 2008 ; Volume 6996 , 2008 ; 0277786X (ISSN) ; 9780819471949 (ISBN) ; Karvar, M ; Bahrampour, A ; Sharif University of Technology
2008
Abstract
The radiation loss in the whispering gallery resonators causes the eigenvalues of the Maxwell equations with the corresponding boundary conditions complex. The corresponding operators are nonhermitian and for these operators the standard perturbation techniques have some difficulties. In this paper by employing the Floquet theorem a new technique for the φ periodic perturbations is developed. The method is applied to obtain the change of resonance frequencies and losses of φ -perturbed microresonators with cylindrical symmetry. The results are compatible with that are obtained by the Volume Current Method
An isolated three-phase soft-switched buck rectifier
, Article 2010 IEEE International Conference on Power and Energy, PECon2010, Kuala Lumpur, 29 November 2010 through 1 December 2010 ; 2010 , Pages 813-818 ; 9781424489466 (ISBN) ; Zolghadri, M.R ; Haghi, R ; Sharif University of Technology
2010
Abstract
In this paper a novel soft switching isolated buck rectifier is proposed. Various switching state sequences of a three-phase three-switch buck-type unity power factor rectifier are reviewed and the value of switching power loss in each state transition is investigated. The switching power loss of the converter is decreased by using zero current switching (ZCS) method. The operation modes of the converter are explained and analyzed. By using an auxiliary circuit with a simple method of energy recovery, the current is diverted away from the main power switches before they are turned off; so, switching losses in the converter are reduced. In this topology, the power transformer has only the...
Hydromagnetic micropump and flow controller. part a: experiments with nickel particles added to the water
, Article Experimental Thermal and Fluid Science ; Volume 33, Issue 6 , 2009 , Pages 1021-1028 ; 08941777 (ISSN) ; Shafii, M. B ; Alavi Dehkordi, E ; Sharif University of Technology
2009
Abstract
The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...