This paper presents a new coupled-inductor based quasi-resonant step-up converter for solar energy applications. The proposed converter requires only one switch and is able to achieve high voltage gain without suffering high voltage stress across the switch. The improved coupled inductor structure employed in the proposed circuit is able to significantly reduce the ratio between the switch voltage and the output voltage allowing for a lower rated switch to be used. The input inductor of the proposed circuit operates in continuous conduction mode (CCM), allowing for the use of small-sized film capacitor at the input side. Maximum power operation is achieved in the proposed converter through the use of variable switching control. The frequency range of the circuit at which ZVS operation functions is lengthened through the use of simultaneous duty cycle control. The description and operating principles of the proposed circuit are provided. Results from simulation on a 100W solar energy system as well as preliminary experimental results on a proof-of-concept prototype are given to highlight the merits of the proposed circuit.
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