A proposed bidirectional three-level DC-DC power converter for applications in smart grids: an experimental validation

The integration of renewable energy sources (RES), energy storage systems (ESS), and electric mobility into smart grids requires the use of DC-DC back-end power converters for adjusting voltage levels. Although a DC-DC converter applied for RES only operates in unidirectional mode, when applied to ESS or EM, the bidirectional mode is a fundamental requisite for exchanging power with the electrical power grid. In this context, this paper presents an experimental validation of a proposed bidirectional three-level DC-DC converter considering its application for smart grids. Traditionally, the DC-DC power converters of such applications are two-level converters. However, by employing a three-level topology, it is possible to improve the quality of the variables controlled by the power converter. Moreover, since the proposed DC-DC converter is controlled to produce a controlled current, the proposed current control and modulation strategies are introduced and described. A complete analysis of the operation principle of the proposed bidirectional three-level DC-DC power converter is presented, supported by experimental validation, employing a laboratory prototype.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019. This work has been supported by FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017, and by the FCT Project newERA4GRIDs PTDC/EEI-EEE/30283/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FCT