A Quadratic Buck-Boost Converter With Continuous Input and Output Currents

This study proposes a novel DC-DC converter topology that features a quadratic buck-boost voltage gain ratio. The quadratic gain of the converter enables it to achieve superior step-down or step-up capability when the duty cycle is higher or lower than 50 percent, as compared to conventional buck-boost converters. While there exist other quadratic buck-boost converters in the literature, the proposed converter offers unique features such as continuity of input and output currents, which reduces the current stress on the input and filter capacitors, making it a suitable option for renewable energy applications. Additionally, unlike its counterparts that have two high-side switches, the proposed converter features only one high-side and one low-side switch, allowing for a simpler gate-driver design. The proposed topology shares a common ground between the load and the source, and has the lowest stored energy with the same performance, indicating a compact size. Steady-state analysis has been conducted in both continuous and discontinuous conduction modes, and the controller design was studied with the aid of small-signal modelling. Simulation and experimental results from a 100 W prototype were used to validate claims and analyses.