PERFORMANCE ANALYSIS OF HIGH STEP-UP DC-DC CONVERTER FOR PHOTOVOLTAIC (PV) SYSTEM

This paper presents renewable energy system which consists of low voltage sources like fuel cells and photovoltaic (PV) cells. Thus the high step-up dc-dc converters are used to produce high step-up gain. Theoretically the boost converter can provide the high voltage gain at large duty cycle. But in practice the voltage gain is reduced, due to losses in utilized components like rectifier diode, power switch, inductor and capacitor. Hence the converter using coupled inductor technique was introduced. However, the leakage inductor cause voltage transients on main switch and also reduce the conversion efficiency. To mitigate the voltage stress on the main switch due to voltage spike/transients, the coupled inductor with active clamp circuit based converters are introduced. In this work, a high step-up dc-dc converter with lossless passive clamp circuit is proposed to reduce stress on the main switch and also to recycle the energy of the leakage inductor. The proposed topology consists of two diodes and two capacitors on the secondary side of the coupled inductor to achieve the high voltage gain. The proposed topology will be analysed in PSIM model in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) of operation and the boundary condition between CCM and DCM will be presented.