HIGH EFFICIENCY FLY-BACK CONVERTER USING RESISTANCE COMPRESSION NETWORK

In applications like photovoltaic systems the low voltage output of solar panels (typically 12 Volts) has to be boosted to high voltage (typically up to 400V) and then inverted to 230 V standard ac supply. This project aims at developing a Fly back based high step up dc-dc converter with high voltage step-up ratios. In a fly back converter, when the current ramps up in the primary, energy is built up in the transformer core. When the MOSFET switches off, this energy is dumped into the secondary, allowing current to flow in the secondary, so the primary current collapses immediately to zero. This causes an immediate rise in current in the secondary, after which, the current in the secondary ramps down linearly as it discharges, supplying energy to the load. The current in the secondary when the MOSFET switches off, is proportional to the peak in the primary, and is determined by the transformer turns ratio. Experimental results from the prototype show that over 97% efficiency is maintained across an input voltage of 40 V with an output voltage of 420 V. These experimental results demonstrate the effectiveness of the proposed design.