Space vector modulation for single-phase transformerless three-leg Unified Power Quality Conditioner

Unified power quality conditioner (UPQC) is an ideal compensation device to improve power quality for sensitive end-users. In this paper, a space vector modulation method is proposed for single-phase three-leg UPQC (TL-UPQC) and one possible special switching sequence with reduced switching losses is discussed based on it. The proposed modulation method is similar to the well-known space vector modulation widely used in three-phase converters, thus brings extra flexibility to the TLUPQC system. Additionally, with the special switching sequence, at least one leg of the TL-UPQC operates at line frequency and improved system efficiency will be obtained. Analysis, along with simulation and experimental results are presented to verify the feasibility and effectiveness of the proposed space vector modulation and switching sequence.