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This paper presents high step-up dc-to-dc converter for low voltage sources such as solar photovoltaics, fuel cells, and battery banks. To achieve high voltage gain without large duty cycle operation, combination of coupled inductor and switched capacitor voltage doubler cells are used. By incorporating active clamp circuit, voltage spike due to the leakage inductance of the coupled inductor is alleviated and zero-voltage switching turn on of the main and auxiliary switch is obtained. Due to the use of MOSFETs of low voltage rating and soft turn on of the switches, conduction loss and switching losses are reduced. This improves the efficiency and power density of the converter. The proposed converter can achieve high voltage gain with reduced voltage stress on MOSFET switches and output diodes. Design and analysis of the proposed converter is carried out, and finally, a 500-W experimental prototype is built to verify theoretical analysis. [ABSTRACT FROM PUBLISHER]

An isolated four channel dc/dc converter with zero voltage switching is proposed as the front-end of multiple inverter structures to integrate renewable and other low voltage energy sources to micro grids. The interleaving technique is adopted to connect each module of proposed converter to a common dc source. This dc source can be a fuel cell stack, PV panels, battery, or any other low voltage dc source. All four channels are interleaved and a phase shift of $90^{\circ }$ is provided between the gate signals of each channels, which reduces the input current ripple. The output port of the proposed converter provide four isolated and regulated dc voltages. These isolated dc sources can be connected in series or parallel or series-parallel manner to obtain required dc-link voltage of various inverter structure. Issues like capacitor voltage balancing of diode clamped multilevel inverters can overcome through the proposed converter. By incorporating a coupled inductor for isolation and energy storage along with voltage multiplier circuit, the proposed converter can achieve higher voltage step up with lower turns ratio and lower voltage stress at moderate duty ratio. Hence, mosfets of low voltage rating (low $R_{DS}(\text{ON})$ ) can be utilized to reduce conduction loss. A 2 kW prototype of the proposed interleaved dc/dc converter is developed and tested with diode clamped three-level inverter, five-level inverter, and three-phase two-level inverter to verify the design. [ABSTRACT FROM AUTHOR]