Regenerative switched-inductor/capacitor type DC-DC converter with large voltage gain for PV applications

Abstract

In grid-connected PV applications, the presence of a transformer not only increases the cost, size and weight, but also decreases the whole system efficiency, especially, under poor irradiation conditions. To eliminate the transformer and to meet DC link voltage, a regenerative switched-inductor/capacitor type DC-DC converter with large voltage gain is proposed in this study. In traditional boost type and derived converters, the voltage gain ratio is limited due to voltage stress on the semiconductor devices and low efficiency because of more components count and large duty cycle operation. The proposed converter recycles the energy in lossless passive components and increases the step-up voltage gain, which improves the efficiency. In addition, the converter possesses fewer ripples and smooth continuous current, which reduces the power loss, elongates lifespan of the input source and restricts electromagnetic interference issues. This study presents detailed operating waveforms, modes of operation and performance characteristics of the proposed converter. In order to validate the operation, 500 W experimental prototype is developed and verified with measured results. The proposed converter yields the peak efficiency of 95.20% for the output power of 440 W.