A Soft Switched, Single-Switch Electrolytic Capacitor-less Step-Up Converter for Photovoltaic Energy Application

In this thesis, a single switch, electrolytic capacitor-less quasi-resonant step-up DC/DC converter is proposed for solar energy applications. The proposed converter is an improved coupled-magnetic based topology that requires only a single switch. By operating the input inductor of the proposed converter in continuous conduction mode (CCM) the required input capacitance is reduced and hence, allows for a small sized film capacitor to be used. In addition, the proposed circuit is able to achieve a large step-up gain while minimizing the ratio between the peak switch voltage and the circuit output voltage. Two different modes of operation are presented and discussed for the proposed circuit which can achieve a very large gain and a very small peak switch voltage to circuit output voltage ratio simultaneously. A maximum power point tracking controller is also developed to work with the proposed step-up DC/DC converter through the use of variable frequency control scheme. Simulation and experimental results on a proof-of-concept, 35V/380V, 100W, 100kHz, hardware prototype are provided for both modes of operation for fixed and varying light intensities to highlight the merits and performance of the proposed converter.