Negative sequence control for DC voltage balancing in three-phase cascaded H-bridge rectifiers considering DC-port failures.

As a vital component of power electronic transformers (PET), the reliability of a cascaded H-bridge rectifier (CHBR) is essential. Therefore, in this paper, a DC-port voltage balance strategy considering DC-port failure is researched to ensure the stable operation of a CHBR. However, if the DC-port voltage balance strategy is adopted to realize the single-phase balance of a CHBR, the three-phase currents become unbalanced. This paper uses a negative sequence control (NSC) strategy that is conducive to balancing DC-port voltage to achieve three-phase current balance. For the DC-port voltage balance, the matrix generation modulation (MGM) algorithm is proposed. In addition, the DC-port voltage balance boundary is analyzed to determine the range of the DC-port voltage balance in the CHBR. A 3-module cascading topology is adopted to demonstrate the MGM algorithm and the NSC strategy. Through experiments, results show the correctness and feasibility of the proposed strategy. [ABSTRACT FROM AUTHOR]