With ever increasing electric energy consumption an‎d price, more attention is paid to further utilize renewable energy sources like solar energy as a solution for confronting environmental problems. In addition, the renewable energy sources are suitable for providing energy to the remote areas which are far from the power grid. Renewable energy sources have intermittent feature an‎d in order to compensate for the generation an‎d consumption power fluctuations, energy storage sources are required. Utilizing separate converter for each source, increases the system volume. Utilizing multi input converters is a good solution to reduce elements count an‎d complexity. Solar energy is among the sources with high availability, but the photovoltaic panels produced voltage is low an‎d should be boosted before connecting to electric grid. Also, with increasing applications that require the return of output energy to the input, bidirectional multi input converters are developed. Soft-switching techniques are utilized to eliminate the semiconductors switching losses. Providing soft-switching condition for semiconductor elements in all power paths, is a design challenge in multi input converters. In this thesis, non-isolated multi input converters with energy storage systems are investigated. In chapter one, the necessity of multi input converters an‎d their varieties are analyzed. In chapter two, common ways for developing multi input converters are investigated an‎d finally multi input high step up or/an‎d soft-switched converters based on three port boost topology which have high element sharing instinctively, are reviewed. In chapter three, by modifying the basic boost three port topology an‎d utilizing switched capacitor technique, two multi input converters with continuous battery current in single-input single-output modes are proposed. The first multi input converter is suitable for low output powers while the second multi input converter is suited for higher power applications. In chapter four, three port boost topology is utilized along with a switch, a capacitor an‎d three wingdings which are coupled with the main inductance to increase the switching frequency, efficiency an‎d voltage gain of the third proposed converter. In chapter five, at first the idea of a non-isolated soft-switched multi input converter which is a combination of the modified three port boost topology an‎d the third proposed converter, is presented.In contrast to the previously proposed converter, an auxiliary winding an‎d the capacitive turn on loss are eliminated which leads to higher efficiency an‎d switching frequency. At the end of chapter five, the idea of a bidirectional multi input single magnetic core converter is proposed which is a combination of the basic buck an‎d boost converters. Thus, the battery current in single-input single-output modes is continuous. In order to verify the theoretical results, the proposed converters in chapter three an‎d four are implemented in the laboratory while the converters in chapter five are simulated by computer. In chapter six, the thesis conclusions are presented an‎d finally some suggestions regarding the continuation of this research are provided

حسين فرزانه فرد

احسان اديب , علي خواجه الدين

اصغر غلامي , حميدرضا كارشناس