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Today, the demand of energy is one of the most important issues of our world. Fossil fuels which have fulfilled main socials’ energy request are limited sources. Besides the Systems that use these types of fuels have low efficiency and also are main sources of air pollution. Therefore, using the renewable energy sources and the high efficiency systems is necessary. In this research, the stationary applications of the fuel cell systems and the development of this clean energy conversion is considered. Although in constructing of fuel cell power plants and stationary units, some types of fuel cell systems have used, but molten carbonate fuel cell (MCFC) has the most application in this fields. In this paper, the design and manufacturing of a 5kW fuel cell system and its fuel and air management, heat and water management, safety and control subsystems are investigated.

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fuel cell

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In this paper, a single switch transformerless high step up dc-dc converter with low voltage stress on the power switch for solar energy application is proposed. In the proposed converter only one power switch is used which makes the control scheme simple as well as reducing the switching power loss. The voltage gain of the proposed converter is higher than the conventional boost converter and buck boost converter. The proposed converter has low voltage stress on the power switch which makes reducing the switching power loss. The proposed converter can be operated in the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). In this paper, different operation modes of the proposed converter, calculation of the voltage gain, the currents that flow through the components, efficiency and capacitors voltage ripple are presented. To verify the operation of the proposed converter, simulation results via PSCAD software and experimental results are provided.

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In this paper, a novel interleaved high step-up converter is proposed through coupled inductors (CI) and built-in transformer (BIT) voltage multiplier cells, which is suitable for renewable energy systems. The combination of these techniques gives a greater degree of freedom to increase voltage gain and reduce voltage stress in power switches without operating the converter in high duty cycles compared to other converters that only include BIT or CI. Therefore, semiconductors with low nominal voltage can be used to reduce conduction losses and cost. In addition, an active clamp scheme is used to ensure ZVS turn-on of power MOSFETs, and ZCS performance is provided by leakage inductances. In such a case, the switching losses are minimized and the reverse current recovery problem is reduced. Due to the proposed interleaved structure of the converter, not only the current stress is minimized, but also the input current ripple is limited, which leads to an increase in the lifetime of the input source. All these factors improve the efficiency and performance of the proposed converter. The performance principles and specifications of the proposed converter are analyzed in detail and the simulation results are presented in PSIM software.