DC link voltage control of back-to-back converter robust to grid conditions

Active rectifier topologies are used for different purposes, especially widespread in renewable generation and distributed energy sources. The most common configuration for active rectifiers is the back-to-back converter. In this article, a back-to-back structure for connecting a variable frequency source to the utility grid is observed and a control algorithm, robust to grid impedance values, is developed for the grid-side converter part. In order to reduce current harmonics, an LC filter is used. Three control loops were developed in a cascaded structure for controlling the grid active and reactive power, and DC-link. Controller parameters were chosen by using the magnitude optimum approach and the root locus method while Truxal-Guillemin approach is used for the DC voltage control due to the complexity of the corresponding DC link model. The obtained control algorithm is validated through simulations in PLECS software for several inductive and capacitive grid impedance conditions.