A novel single-phase bidirectional nine-level converter employing four quadrant switches

Abstract

A novel bidirectional ac-dc multilevel converter based on four quadrant switches is proposed. This new converter can establish nine voltage levels downstream the coupling filter used to interface with the power grid, and, comparing with conventional two- or three-level converters, it operates with improved ac-side current, both for operation as active rectifier (on-grid), grid-tied inverter (on-grid) or voltage inverter (off-grid). A detailed description of the converter is exhibited, highlighting its main advantages according to the applications where it can be employed in smart grid scenarios. In order to confirm its viability, a considerable set of results is presented and discussed, establishing an overall comparison with conventional converters. Moreover, the proposed converter is validated operating as active rectifier, as grid-tied inverter, and as voltage inverter, controlled in closed-loop by current or voltage. The details of the proposed power converter hardware and the implementation of the digital algorithm, based on a fixed switching frequency structure, are clarified and discussed throughout the paper.This work has been supported by COMPETE: POCI-010145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013. This work is financed by the ERDF – European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation – COMPETE 2020 Programme, and by National Funds through the Portuguese funding agency FCT within project SAICTPAC/0004/2015 – POCI – 01–0145–FEDER–016434. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by of the FCT project 0302836 NORTE-01-0145-FEDER-030283.info:eu-repo/semantics/publishedVersio