A Reduced-Switch High-Frequency Isolated Single-Phase Buck-Boost AC-AC Converter Without Commutation Issue

In this paper a reduced-switch high-frequency isolated single-phase buck-boost AC-AC converter without commutation issue, is proposed. The proposed converter produces both inverting and non-inverting output voltages in boost and buck modes, utilizing a single high-frequency switch alongside four line-frequency switches. Inherent commutation is achieved without the need for positive and negative switching cells, ensuring all components remain active throughout both half-cycles of the input voltage. This approach resolves the commutation issue without the use of snubber circuits or bidirectional switches, while maintaining continuous input current, which negates the need for an LC filter. These advantages simplify the switching pattern, reduce circuit components, and enhance overall efficiency. A comparative analysis with other converters, focusing on total voltage and current stress on switches, switching device power (SDP) index, and volume density, highlights the proposed converter’s compactness and cost-effectiveness. The operating principles are explained, and key relationships are presented. Finally, simulation results from PSCAD/EMTDC software confirm the converter’s performance and validate its design claims.