Extended Boosting Range-Based-Non-Isolated Buck-Boost Converters With Continuous Input Current and Common Grounded Structure

This article presents extended boosting range-based nonisolated buck-boost converter (NIBBC) topologies exhibiting continuous input current, common grounded structure, and enhanced quadratic buck-boost conversion ratio. The NIBBC Type-1 and Type-2 configurations are evolved from the conventional quadratic buck-boost converter (CQBBC) by appropriately inserting a capacitor-diode (CD) cell into the upstream and downstream sides. Furthermore, the NIBBC Type-3 converter is evolved from the cascading of boost converter and modified polarity inverting boost converter. Compared to CQBBC, the proposed NIBBC Type-3 converter offers an enhanced quadratic voltage conversion ratio with low ripple content in the source current. Moreover, the proposed topologies have the outperforming features of low switch device power rating and low voltage stress on the intermediate capacitor (C-2) over the existing quadratic-type buck-boost configurations. The detailed mathematical formulations of the steady-state voltage and current relations using the time-domain approach for the passive and active components are presented for the NIBBC Type-3 converter. The state-space model matrices are also derived from the equivalent circuit analysis. Thereafter, a comprehensive performance review of the evolved NIBBC topologies and existing quadratic-type buck-boost structures is discussed. The performance features of the proposed NIBBC Type-3 are validated through the steady-state and closed-loop dynamic measurement results obtained from the lab-scale experimental prototype.