Design of a high-gain da-da converter for photovoltaic systems
2021
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Danışman: Ahmet Gündoğdu
Özet (EN)
da-da converters with high switching frequency have been a part of many technological devices used in daily life. These converters are desired to have characteristics such as small size and high efficiency. These high-frequency switched converters are widely used in industrial applications such as battery charging stations, renewable energy systems, fuel cells, power factor correction circuits, led lighting due to their ease of control, fast response and high power density. These da-da converters with high voltage gain are especially used to obtain the input voltages of microswitches in photovoltaic systems. Their widespread use in photovoltaic systems has intensified research on these converters. In this thesis, a high-gain interleaved converter circuit was modeled mathematically and the simulation model was created in MATLAB / Simulink environment. The applicability of the results obtained through simulation studies has been discussed. The studied transformer structure consists of inductances combined to provide high output voltage with low duty period. This structure is integrated in the switched step-up type converter. An important advantage of this converter structure is that it reduces voltage stress on power switches and diodes. So, low cost and high performance semiconductor switching elements can be used. In addition, the reverse recovery problem of all diodes is reduced and the zero current switching (ZCS) operation of the switching elements is also provided. In addition, passive locking circuits are used to suppress the voltage spikes that occur during the closing moments of the switching elements. The design and simulation study of a 200W da-da converter with 25V input voltage and 400V output voltage was carried out. As a result of the simulation study, the working principle and steady state stability analysis of the converter structure are explained.