A Simple 36-Pulse Rectifier With Passive Pulse-Tripling Circuit at the DC Side

A series-connected 36-pulse rectifier with passive pulse-tripling circuit (PPTC) on the dc side is proposed in this article. The proposed rectifier consists of a series-connected 12-pulse rectifier and a PPTC. The PPTC includes a passive current forming network, a single-phase auxiliary transformer with dual secondary windings and two auxiliary single-phase rectifiers (ASRs). One ASR in PPTC is connected in series with the load to directly modulate the output current of rectifier bridges. The other ASR in PPTC is connected in parallel with the load to modulate the output current of rectifier bridges according to the relationship between its input voltage and load voltage. Composite modulation of the two ASRs increases the pulse number of the rectifier from 12 pulses to 36 pulses. The resulting rectifier obtains an approximate sinusoidal input current with less than 5% THD. Only a few low-capacity passive components are sufficient given the absence of active components in the proposed scheme. The proposed scheme presents advantages of simple circuit structure, easy implementation, and high reliability. Detailed analysis and experimental results are provided to verify the effectiveness of the proposed scheme.