Novel passive harmonic suppression method for series-connected multi-pulse rectifiers

To improve the power quality and reliability of series-connected multi-pulse rectifiers (MPR), a passive harmonic suppression method is proposed in this paper. According to the topology of the rectifier, the operation modes are examined, and the operating waveforms are studied based on the operation modes. Based on the operating waveform of the rectifier, the relationship between the input voltage and the turns ratio of the auxiliary single-phase transformer (AST) is obtained, and the optimal turns ratio of the AST is calculated. The obtained results express that the input voltage THD is 4.4%, and that the input current THD is about 2.6%. The magnetic rating of the AST is only 1.72% of the output power. The proposed passive harmonic suppression method has the advantages of low loss and good harmonic suppression capability.