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Operation and design analysis of an interleaved high step-up DC–DC converter with improved harnessing of magnetic energy
, Article International Journal of Circuit Theory and Applications ; Volume 49, Issue 2 , 2021 , Pages 221-243 ; 00989886 (ISSN) ; Tarzamni, H ; Kolahian, P ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
In this paper, a new interleaved DC–DC converter based on a coupled and a single input inductor is proposed. The suggested high step-up converter utilizes various inductive and capacitive methods to transfer magnetic energy more efficiently. The output voltage is regulated with the switches' duty cycle and the coupled inductor (CI) turns ratio, which provide a wide output voltage range. Interleaving improves the converter reliability, employs both the first and third areas of CI's B-H plane, cancels DC component of the CI, and reduces the input current ripple of the proposed converter with twice switching frequency. Utilization of two output ports for voltage stress and ripple reduction in...
Modeling and control of zero-sequence circulating current in parallel converters with space vector modulation
, Article IEEE Journal of Emerging and Selected Topics in Power Electronics ; Volume 5, Issue 1 , 2017 , Pages 363-377 ; 21686777 (ISSN) ; Amouzegar Ashtiani, N ; Parniani, M ; Mokhtari, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
The use of parallel converters is one of the most practical solutions to solve the problem of transmitting bulk power generated in megawatt wind turbines to the grid. In spite of several advantages of paralleling, some considerations must be taken into account. Zero-sequence circulating current flowing between parallel converters is one of these concerns. Characteristic differences and discrepancy of zero-axis duty cycles of the parallel converters are considered as the main origins of this current. This paper investigates another source of this phenomenon in space vector modulation controlled converters. This unnoticed source is the notable third-harmonic voltage generated in the...
Modification in Topology and Control Method for Improving Performance of Modular Multilevel Converter in 2N+1 and N+1 Modulation
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
In Modular Multilevel converter, it is necessary to attain different objectives simultaneously. One of the most effective control methods which can cope with this kind of systems is the Model Predictive Control (MPC). This method predicts the values of control objectives based on different feasible states and determines the optimal one using cost functions. The number of feasible states can increase when the number of switches increases in the converter. This makes the MPC unable to be applied in the MMCs with hundereds of submodules (SMs) in each arm because of its heavy computational burden. In this thesis, a modified model predictive control is proposed to reduce the computational burden....
Control of parallel three- phase inverters using optimal control and SVPWM technique
, Article IEEE International Symposium on Industrial Electronics, 5 July 2009 through 8 July 2009 ; 2009 , Pages 1823-1828 ; 9781424443499 (ISBN) ; Mokhtari, H ; Sharif University of Technology
Abstract
In this paper, optimal control strategy is applied to parallel three-phase inverters using SVPWM technique. The three-phase system is transformed to a synchronous-stationary frame, suitable cost functions are defined, and the switching schemes are determined for the inverters. The control strategy minimizes the circulating current between the inverters, therefore, proper load sharing scheme is achieved. Simulations are performed for steady state and load change operation, and the results which show the suitability of the controller are provided. ©2009 IEEE
Analysis and Control of Circulating Current in High-Power Full Converter Wind Turbines with Modular Structure
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
This thesis aims at developing control system of a full converter wind turbine with modular and parallel back-to-back converters. Modular structures and paralleling of power electronic converters are the state-of-the-art methods for increasing their transferable power to the grid. Technological advances in high power wind turbines, especially for the offshore installations, which contain permanent magnet synchronous generators with back-to-back full converters, promote the use of modular structures.
In addition to developing the regular control systems of wind turbines for modular structures, selection of appropriate structures, power sharing between parallel converters and mitigation of...
In addition to developing the regular control systems of wind turbines for modular structures, selection of appropriate structures, power sharing between parallel converters and mitigation of...
Design of a bridgeless PFC with line-modulated fixed off-time current control and zero-voltage switching
, Article PECon2010 - 2010 IEEE International Conference on Power and Energy, 29 November 2010 through 1 December 2010 ; 2010 , Pages 129-134 ; 9781424489466 (ISBN) ; Zolghadri, M. R ; Nasirian, V ; Noroozi, N ; Sharif University of Technology
Abstract
In this paper, the Line-Modulated Fixed Off-Time method is used as the current control strategy for a Power Factor Corrector (PFC) pre-regulator. A zero voltage switching PWM (ZVS-PWM) auxiliary circuit is configured to perform ZVS in the switches. Soft commutation of the main switch is achieved without additional current stress. A significant reduction in the total conduction loss is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path .The proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode...
A modified indirect model predictive control for modular multilevel converters
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 1366-1371 ; 9781509059638 (ISBN) ; Ravanji, M. H ; Parniani, M ; Sharif University of Technology
Abstract
Modular multilevel converter (MMC) is among the promising topologies used in high-voltage/power purposes, especially for high-voltage direct-current (HVDC) transmission systems. In this paper, a modified model predictive control (MPC) strategy for an MMC-HVDC system is presented. In the proposed MPC strategy, output current, circulating current and capacitors voltage are controlled separately. In order to reduce the computational burden of the controller, the output current is controlled directly without any optimization. For suppression of the circulating current, capacitors voltage variations are employed to settle the converter arms voltages to their reference values. In addition, the...
An enhanced hybrid modular multilevel converter for improved performance
, Article IEEE Transactions on Power Electronics ; 2018 ; 08858993 (ISSN) ; Ravanji, M. H ; Parniani, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
This paper proposes an enhanced hybrid modular multilevel converter (MMC), which utilizes a combination of halfbridge submodules (HBSM) and at least one full-bridge submodule (FBSM). In the proposed structure, FBSMs work with half of the HBSMs nominal voltage in each arm. Due to the presence of FBSMs, HBSMs switching frequency drops significantly, which reduces the converter power loss compared to half-bridge based MMCs. Furthermore, because of redundant FBSMs, (2N+1)-modulation can be employed to generate the output voltage without increasing the circulating current, thus the converter performance is improved notably. Besides, with the redundant FBSMs the converter can continue its...
Enhanced hybrid modular multilevel converter with improved reliability and performance characteristics
, Article IEEE Transactions on Power Electronics ; Volume 34, Issue 4 , 2019 , Pages 3139-3149 ; 08858993 (ISSN) ; Ravanji, M. H ; Parniani, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper proposes an enhanced hybrid modular multilevel converter (MMC), which utilizes a combination of half-bridge submodules (HBSM) and at least one full-bridge submodule (FBSM). In the proposed structure, FBSMs work with half of the HBSMs nominal voltage in each arm. Due to the presence of FBSMs, HBSMs switching frequency drops significantly, which reduces the converter power loss compared to half-bridge based MMCs. Furthermore, because of redundant FBSMs, (2N + 1)-modulation can be employed to generate the output voltage without increasing the circulating current, thus, the converter performance is improved notably. Besides, with the redundant FBSMs, the converter can continue its...