Search published articles


Showing 2 results for Hemmati
Hybrid Z-Source DC-DC Converter with ZVZCS and Power Transformer Resetting: Design, Modeling, and Fabrication
H. Torkaman, T. Hemmati,
Volume 14, Issue 1 (March 2018)
Abstract
This paper introduces a novel two transistors forward topology employing a z-source to achieve ZVZCS and power transformer resetting for various applications. Comparing with the forward converter, this topology has the advantage of displaying ZCS condition with an added Z-Source and no additional switches when the switches turn on, and that ZVS condition happens when the switches turn off. Duty cycle of the topology can exceed 50 percent. As a result, these converters are suitable for applications with high efficiency. In this paper, structure and properties of the topology will be discussed in details. Then the design principles will be presented. Finally, the benefits aforementioned will be approved in practice through a simple forward converter.

Effects of Stress Grading Materials’ Properties on the Performance of 20-kV Cable Terminations
V. Abbasi, S. Hemmati, M. Moradi,
Volume 15, Issue 1 (March 2019)
Abstract
Stress grading (SG) layer in cable terminations limits the critical electric field and properties of SG materials are important issues which have to be considered during manufacturing and selecting procedure. In this paper, two different types of (SG) materials are analyzed by both theory and test. According to the applied theory, important parameters as: electrical resistivity, breakdown voltage and thermal conductivity are determined by experiments. Experimental steps are defined in the paper with which theory and experiments are matched together to complete the investigation. The paper discusses electro-thermal breakdown theory and quality of two different SG layers based on the test results. The theory and experimental procedure can be used for prediction of breakdown voltage in cable terminations. The employed method is useful for qualifying the cable terminations by users who want to buy and install heat shrink cable terminations.

Page 1 from 1     
Creative Commons License
© 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.