A Group of High Step-Up DC–DC Topologies Based on Conventional Buck-Boost Converter Utilizing Coupled-Inductors and Voltage Multipliers

Abstract

Traditional high step-up DC–DC converters for renewable energy sources (RESs) often suffer from critical limitations, including the requirement for extreme duty cycles to achieve high voltage gains, elevated voltage and current stresses on semiconductors, and the imposition of full output voltage on the output capacitor and diodes. This paper presents a single-switch, non-isolated high step-up DC–DC converter that overcomes these challenges by combining a coupled inductor (CI) and voltage multiplier (VM) cells with a modified buck–boost–converter-based structure. The proposed topology achieves a high voltage conversion ratio while effectively distributing voltage stresses among the circuit components. The coupled inductor mitigates diode reverse-recovery problems, and a passive clamp circuit suppresses voltage spikes arising from leakage inductance, thereby reducing switch stress and enhancing its efficiency. Comprehensive theoretical analysis, along with comparative evaluations against similar configurations, demonstrates that the proposed converter delivers high voltage gain across the full duty-cycle range with the minimum normalized switch voltage stress. It also exhibits among the lowest diode voltage stresses and utilizes relatively low-value passive components, all within a simple structure employing only one power switch and one magnetic core. Four extended topologies utilizing an extra inductor or coupled inductor alongside an extra power switch, offering one more degree of freedom are also developed, analyzed in their various operational states, and simulated in this paper. Experimental validation of the main topology, operating at 300 W and 50 kHz while stepping up 30 V to 380 V, confirms the provided analyses and proper practical performance.