DVR with five-level converter based on three-and two-level legs connections

This paper proposes three topologies of multilevel dynamic voltage restorer (DVR) with application in three-phase systems (balanced and unbalanced) to compensate sags/swells. The topologies use three independent dc-links (one per phase) and each converter is mounted with one three-level NPC leg (3L) and one two-level leg (2L), furnishing a five-level (5L) voltage at its output. This proposed topologies aims to give an intermediate solution between the 2L converter and the 3L converter (e.g., 5L NPC converter). The control system, including the PWM technique, is presented and comparisons between the proposed topologies and conventional topologies are discussed. Simulation and experimental results are presented in order to validate the theoretical approaches.