ZNBILL, L. Nízoenergetické měniče v pevné fázi pro Energy harvesting [online]. Brno: Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií. 2021.
Mrs. Laila Znbill began her doctoral studies at the Faculty of Electrical Engineering and Communication of Brno University of Technology in the school year 2014/2015. The aim of her doctoral study was focused on low-energy converters for energy harvesting and related production technologies. This broad topic includes physical issues of converter function, chemical and physical processes in its production and operation, as well as issues of electronic circuits and transformers for use in DC / DC converters, which had to be able to process very low energy flows at voltage levels less than 100 mV. In accordance with the focus of the Department of Microelectronics, the dissertation was prepared on the topic Low Energy Solid State Converters for Energy Harvesting. In the first and second year of her studies, Mrs. Ing Laila Znbill focused mainly on the issue of low-voltage DC to DC converters and photovoltaic cells. She was very well oriented in this issue and subsequently several prototypes (functional samples) and publications were created. In the following years, experiments were performed with photovoltaic cells and low-voltage DC to DC converters. Furthermore, the concept of thermoelectric converters using organic semiconductor PEDOT:PSS was developed and several types of thermoelectric generators were proposed. The proposal of the thermoelectric generator with a vertical structure was processed into the final design form. She was well oriented also in this part of the work and each design steps were published. In my opinion, the benefit of the presented work lies in the following areas. Low voltage DC to DC converters capable of operating with an input voltage as low as 50 mV, including modifications to increase their efficiency. Special low power transformers with a large conversion ratio for low-voltage DC to DC converters. Precautions for low power low voltage operation. The start-stop operation and possibility to work in parallel under a common load which makes it possible to process energy from sources where the power supplied may fluctuate or fall out. Analysis of processes and limitations associated with operation at very low voltages. Verification of proper function of designed DC to DC converters at low light operation of photovoltaic cells in single mode operation. Verification of the possibility of implementing the necessary circuits in IC technology. The method of dynamic measurement of serial and shunt resistances of photovoltaic cells, which allows the measurement of very small resistances as well as high resistances to be made with standard instruments available. The analysis of the applicability of different types of photovoltaic cells based on measuring and comparing their parameters and verifying the results in the experiments. The design of different concepts of thermoelectric converters, including detailed calculations. Design of the structure with vertical arrangement of TEG, which ensures small series resistance of the entire thermoelectric generator and verification of its feasibility. In solving the assigned tasks, Mrs. Laila Znbill worked independently and met the agreed deadlines. However, due to the relatively large scope of the work, finalizing of the work was postponed and she had to switch to distance learning. The completion and submission of the work was largely influenced by the Covid 19 pandemic, both in terms of limited access to the faculty premises and in terms of limited mobility and communication. While working on her dissertation Mrs. Laila Znbill proved that she is able independently perform the activities with the character of scientific work and she submitted the dissertation which meets the requirements that are usual for dissertations. Therefore, I recommend her dissertation for defense.
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