13973

12697

كارشناسي ارشد

الكترونيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

۱۳۹۷

دوازده، [۶۶]ص.: مصور، جدول، نمودار

احسان اديب

حسين فرزانه فرد

نسرين رضايي

1397/07/21

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID12697

Soft Switching High Step up Converters for Renewable Energy Applications Alireza Nasri mail alireza nasri@ec iut ac ir Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan Iran Degree M Sc Language Farsi Supervisor Dr Ehsan Adib e adib@cc iut ac ir Abstract High step up DC DC converters are vastly applied in renewable energy systems Due to the growth of globalenergy demand and environmental problems caused by fossil fuels use of renewable energy sources is growing But these kind of sources are expensive and thus the power electronic circuits should operate efficiently in orderto harvest maximum energy from these sources One of the main issues of these energy sources like solar cells istheir low output voltage The basic topology in order to step up the voltage is the conventional boost converter But this converter can not work under extreme duty cycles So High step up DC DC converters should be used The main challenges in this area are presenting simple structure avoiding extreme duty cycles reducing voltageand current stress of devices solving reverse recovery problems of diodes reducing input current ripple andproviding soft switching condition for switches and diodes Soft switching is important because it would reduceswitching losses and improve the efficiency At the beginning of this thesis non isolated boost converters are reviewed Then soft switching and high stepup techniques which are employed in these converters are analyzed Afterwards two high step up soft switchingconverters are presented In the first converter coupled inductors and a capacitor are placed in series with theoutput in order to increase the voltage gain To achieve soft switching an auxiliary circuit is used Before turningthe main switch on the auxiliary switch turns on and the snubber capacitor of the main switch is discharged ina resonance manner The auxiliary circuit dose not need the leakage inductance energy to discharge the snub ber capacitor therefore it can provide load independent soft switching The second proposed converter is theinterleaved structure of the first converter In this converter soft switching is achieved and the input currentripple is reduced greatly In order to prove theoretical analyses simulation results are provided at the end of eachchapter To verify the simulation results experimental results of the first converter is also presented Finally theconclusions of this thesis and the recommendations to continue this research are presented Key Words High step up DC DC converters Soft switching Interleaved boost converter Coupledinductors

احسان اديب

حسين فرزانه فرد

نسرين رضايي