Design and development of high step-up single-switch DC/DC converters for micro-inverter applications

Distributed energy systems, especially solar photovoltaic (PV), batteries and fuel cells (FC), are now key players in sustainable power generation. Hence, these sources require efficient high-step-up DC–DC converters to interface low-voltage inputs with high-voltage DC buses.

However, traditional converters such as boost and buck-boost require extreme duty cycles to achieve high voltage gains. For instance, achieving a gain ratio of 8 to 10 requires a duty cycle of 0.87 to 0.9. Under these operating conditions, the switch and diode currents increase approximately by a factor of (1/(1-δ)), which significantly increases conduction losses and growth in diode reverse-recovery losses due to higher diode current and switching stress. <br><br>To overcome these limitations, this thesis proposes and experimentally validates three novel non-isolated quadratic boost derived DC/DC converter topologies: QBĆUK, QBC-SEPIC and 3QBC_(SL/VL), which systematically address the fundamental limitations of conventional QBCs.