High-voltage gain SEPIC-based DC-DC converter without coupled inductor for PV systems

A new single-ended primary-inductor converter (SEPIC)-based DC-DC converter suitable for photovoltaic (PV) systems is introduced. The proposed converter has the advantage of continuous input current which reduces the input voltage ripple across the PV panels. Furthermore, it can provide a higher-voltage gain at smaller duty cycles when compared with counterpart SEPIC-based topologies which feature the absence of a coupled inductor. A smaller duty cycle for a given voltage gain translates to a lower-current ripple of the inductors, reduced conduction losses, and alleviated voltage stresses of the semiconductor switches. The proposed converter also benefits from a simpler structure and control scheme. The operational principles and the steady-state analysis are studied under both continuous conduction mode and discontinuous conduction mode. A comparative study between the proposed converter and seven counterpart topologies is also included. A laboratory prototype was built and tested. The experimental results are discussed in light of the theoretical analysis.