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Showing 4 results for Mohamadian

S. M. Dehghan, A. Yazdian, M. Mohamadian,
Volume 2, Issue 2 (April 2006)

In this paper a hybrid active DC line conditioner for fluctuations and ripples reduction in voltage and current of DC power systems is proposed. Malfunctions in operation of equipments and systems which are supplied by low quality distribution power systems are one of the main effects of DC voltage ripple. In the proposed configuration a hybrid system including series and shunt active line conditioners for ripple reduction of load voltage and source current is used. Simulation and experimental results are provided to show the performance of the proposed configuration in different states.
S. M. Dehghan, M. Mohamadian, A. Yazdian, A. H. Rajaei, Mr H. Zahedi,
Volume 6, Issue 4 (December 2010)

This paper presents a modified nine switch inverter with two inputs and two Z-source networks. This inverter has two DC inputs and two AC outputs. Input DC voltages can be boosted to the required level. Amplitude, frequency and phase of AC output voltages can be controlled, independently. The proposed converter can be used in applications with two unregulated DC sources, which require feeding two independent loads. Compared to the conventional structure, the proposed converter requires reduced number of semiconductor switches hence improved converter reliability and less volume. Performance of the proposed inverter is verified by experimental results.
S. Mohamadian, H. Azizi Moghaddam,
Volume 16, Issue 1 (March 2020)

Linear AC power supplies can be replaced by their nonlinear switching counterparts due to the lower voltage drops and higher efficiency and power density of switching-mode inverters. Multilevel cascaded H-bridge (CHB) converters are the preferred inverter structure because of modular configuration, control, and protection. The output voltage quality in CHB converters depends on the number of output levels. Asymmetric CHBs (ACHBs) produce an output voltage with higher number of levels with respect to CHBs for the same number of cascaded modules. This results in the reduction of power supply size, voltage drops, and losses. Considering the relative high switch counts, analysis of the effect of conduction and dead-time voltage drops on the inverter output characteristics is an important challenge in designing multilevel converters. In this paper, a generic algorithm is presented to calculate the conduction and dead-time voltage drops of ACHBs utilizing level-shifted modulation. These voltage drops give the necessary information for the design of heatsinks, switch selection, output impedance estimation, and the compensation schemes. It is shown through theoretical and simulation studies that the aforementioned voltage drops of ACHBs are to be calculated in a different manner with respect to the CHBs which mostly use the phase-shifted modulation.

H. Azizi Moghaddam, A. Farhadi, S. Mohamadian,
Volume 18, Issue 2 (June 2022)

In the new advanced drive schemes, identification and modeling of the load complex characteristics can play an important role to predict the dynamic performance of the proposed control strategy. The novelty of this paper consists in the classification of the different types of the nonlinear loads which the electrical drive systems may encounter. In this study, nonlinear components of mechanical loads are divided into two groups. The first type includes nonlinear phenomenon caused by the nature of load which is predictable and identifiable. Another type of loads nonlinear characteristic happens due to the occurrence of a mechanical fault in motor, coupling or load parts. Generally, this type of non-intended nonlinear effect is not predictable and often occurs in the installation and operation stage of the drive system utilization. In this paper, the performance of an induction servo drive system has been simulated under the influence of different types of non-linear industrial loads.

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© 2022 by the authors. Licensee IUST, Tehran, Iran. This is an open access journal distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license.