Comparative Analysis of Fourth-Order Non-Isolated DC-DC Converters: Ćuk, SEPIC and Zeta

This paper presents a comparative study of three fourth-order non-isolated DC-DC converters: Ćuk, SEPIC, and Zeta. Analytical expressions for output voltage ripple were derived for each topology, and their accuracy was validated through numerical simulations. The investigation includes the evaluation of static characteristics, ripple behavior, and efficiency under various duty-cycle conditions. Simulation results demonstrate that the Ćuk converter achieves significantly lower output voltage ripple compared to the buck–boost topology, while SEPIC provides continuous input current and flexible buck–boost operation. The Zeta converter exhibits output voltage ripple that is independent of load variations, confirming its suitability for applications requiring high voltage stability. Efficiency calculations, based on simulation data, show that all three converters achieve high performance, with peak efficiencies above 94% under ideal component assumptions. The results highlight the advantages and limitations of each topology, offering valuable insights for their application in renewable energy systems and power electronics.