Single-stage, single-phase, ac–dc buck–boost converter for low-voltage applications

The suitability of a single-stage ac-dc buck-boost converter for low-voltage applications is investigated. In-depth discussion and analysis of the converter´s operating principle, basic relationships that govern converter steady-state operation and details of the necessary control structures needed to comply with the grid code are provided. The validity of the proposed system is confirmed using power system computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) simulations, and is substantiated experimentally. The buck-boost converter under investigation has good dynamic performance in both buck and boost modes, and ensures near unity input power factor over the full operating range, whilst having fewer devices and passive elements than other published versions of the buck-boost converter.