Improving voltage imbalance in inverter-based islanded microgrids during line-to-line short circuits- Miguel Castilla, Jaume Miret, Luis García de Vicuña, Ángel Borrell, Carlos AlfaroDepartment of Electronic Engineering, Universitat Politècnica de Catalunya, Vilanova i la Geltrú, Spain Department of Electric Engineering, Escola Universitària Salesiana de Sarrià, Barcelona, Spain-

 Abstract

 Line-to-line short circuits are the transient disturbances that cause the highest currents as well as the largest voltage imbalances in inverter-based microgrids. This paper presents a control scheme for grid-forming inverters in islanded microgrids that limits the current to a safe value during these types of short circuits while providing a lower voltage imbalance compared to state-of-the-art current limiting techniques. This control scheme is based on reducing both the amplitude of the reference voltage with the maximum amplitude of the reference current and the instantaneous reference voltage with only the inductive component of the virtual impedance. The combination of these two control actions provides low voltage imbalance, as the theoretical and experimental studies reveal. This voltage imbalance improvement is the main contribution of this paper and is maintained when the microgrid supplies linear and non-linear loads. In the theoretical study, the paper includes control design guidelines to satisfy static and dynamic specifications. The theoretical predictions are validated by means of experimental results measured in a laboratory microgrid. A practical performance comparison of current limiting techniques based on experimental tests is also reported

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https://upcommons.upc.edu/handle/2117/387136

“Active Gate Switching Control of IGBT to Improve Efficiency in High Power Density Converters” Thesis submitted in partial fulfilment of the requirement for the PhD degree issued by the Universitat Politècnica de Catalunya, in its Electronic Engineering Program

 “Active Gate Switching Control of IGBT to Improve Efficiency in High Power Density Converters” 

Thesis submitted in partial fulfilment of the requirement for the PhD degree issued by the Universitat Politècnica de Catalunya, in its Electronic Engineering Program 

by Hamidreza Ghorbani 

Director: Dr. Prof. Jose Luis Romeral Martinez Co-Director: Dr. Eng. Vicent Sala

Abstract 

Insulated gate bipolar transistor (IGBT) power semiconductors are widely employed in industrial applications. This power switch capability in high voltage blocking and high current-carrying has expanded its use in power electronics. However, efficiency improvement and reducing the size of products is one of main tasks of engineers in recent years. In order to achieve high-density power converters, attentions are focused on the use of fast IGBTs. Therefore, for achieving this desire the trend is designing more effective IGBT gate drivers. In gate drive (GD) controlling, the main issue is maintaining transient behavior of the MOS-channel switch in well condition; when it switches fast to reduce losses. It is well known that fast switching has a direct effect on the efficiency improvement; meanwhile, it is the major reason of appearing electromagnetic interference (EMI) problems in switched-mode power converters. Nowadays the most expectant of an active gate driver (AGD) is actively adjusting the switching transient through simple circuit implementation. Usually its performance is compared with the conventional gate driver (CGD) with fixed driving profile. As a result a proposed AGD has the capability of increasing the switching speed while minimizing the switching stress. Different novel active gate drivers (as feed-forward and closed-loop topologies) have been designed and analysed in this study. To improve the exist trade-off between switching losses and EMI problem, all effective factors on this trade-off are evaluated and considered in proposed solutions. Theoretical developments include proposed controlling methods and simulated efficiency of IGBTs switching control. The efficiency improvement has been pursued with considering EMI study in the proposed active gate controller. Experimental tests have been conducted to verify the design and validate the results. Beside technical aspects, cost study has also considered in the closed-loop GD. The proposed gate drivers are simple enough to allow its use in real industrial applications.

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https://upcommons.upc.edu/bitstream/handle/2117/168574/THG1de1.pdf

Návrh a realizace obousměrného DC/DC měniče Design and Realisation of Bidirectional DC/DC Converter By Bc. Antonín Tomšů -2016 VŠB – Technická univerzita Ostrava Fakulta elektrotechniky a informatiky Katedra elektroniky

Návrh a realizace obousměrného DC/DC měniče Design and Realisation of Bidirectional DC/DC Converter By Bc. Antonín Tomšů -2016 

VŠB – Technická univerzita Ostrava Fakulta elektrotechniky a informatiky Katedra elektroniky

 Abstract 

The diploma thesis deals with design and subsequent implementation of a bidirectional DC/DC converter. Theoretical part is an analysis of galvanic insulated inverters together with a description of the function of the peripheral circuit. Practical part deals with the dimensioning and selection of components for the implemented drive, which included a selection of IGBT transistors, exciters, design of medium-frequency transformer, capacitors, chokes, current and voltage sensors, calculation of the power dissipation and cooling. In the next part of the diploma thesis is verification of connection through simulation function in programming environment LTspice. The last part contains description of a laboratory model realized by the bidirectional DC / DC converter with a summary of the results.

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https://dspace.vsb.cz/bitstream/handle/10084/115788/TOM0106_FEI_N2649_2612T015_2016.pdf?sequence=1&isAllowed=y

Řídicí jednotka reverzibilního DC/DC měniče-Control Unit of Reversible DC/DC Converter-Bc. Michal Chudárek-VŠB- TECHNICKÁ UNIVERZITA OSTRAVA Fakulta elektroniky a informatiky Katedra elektroniky

 

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https://dspace.vsb.cz/bitstream/handle/10084/108550/CHU0009_FEI_N2649_2612T015_2015.pdf?sequence=1&isAllowed=y

THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ JEAN MONNET DE SAINT-ÉTIENNE Ecole Doctorale Sciences, Ingénierie, Santé : ED SIS 488 Discipline : Optique Photonique Hyperfréquence Présentée et soutenue publiquement le 26 Mars 2014 Par Khamis YOUSSOUF KHAMIS Modélisation des Transformateurs Planaires Intégrés

Summary 

The use of passive components has experienced significant growth in recent decades, particularly in the field of mobile telephony and embedded electronics. The work presented in this thesis is part of a project between the LT2C laboratories of UJM and Ampère of INSA LYON. The objective of this thesis is the modeling of signal micro-transformers used to isolate the power (Driver IC) and control (JFET or MOSFET) parts. The points addressed in this thesis are the choice of transformer structures which meet the project requirements, the development of a transformer model which takes into account in particular the losses and the evolution of the permeability of the magnetic material and the different capacitive couplings. . Simulations using HFSS were carried out in order to design the selected structures and validate the developed model. Manufacturing steps compatible with those of microelectronics were used to fabricate one-layer and two-layer prototypes of magnetic material with different configurations. A high frequency characterization (2MHz-200MHz) using the vector network analyzer was carried out and finally a comparative study between the simulation results and the measurement results is the subject of a presentation. 

 VIEW FULL TEXT:https://core.ac.uk/download/pdf/52639727.pdf