A Family of Transformerless Step-Up DC-DC Converters: Analysis, Comparison and Experiment

The main focus of this work is to propose and analyze three new converter topologies for high-voltage gain applications. These topologies aim to expand the use of voltage-boosting techniques and address the limitations found in existing methods. The topologies are mathematically formulated to provide a semi-quadratic gain function in terms of the duty cycle. The first topology has a gain function of (3 + D)/(1 - D)2, while the remaining two topologies have gain functions of (3+ 5D)/(1- D)(2). A comparative study against other reported topologies is conducted to assess the performance of the proposed topologies in terms of gain per component, size, and volume, showing better performance. Experimental results from 100 W prototypes operating at a 50% duty cycle validate the theoretical predictions. The experimental waveforms for all components closely match the analytical equations, confirming the feasibility of the proposed topologies. Additionally, an efficiency sensitivity analysis against duty cycle variations is performed, aligning with expectations considering the inherent losses at high voltage gains and duty cycles.