Basic connections and strategies of isolated phase-shifting transformers for multipulse rectifiers: A review

The phase-shifting transformers play a key role in the multipulse rectifier's performance. This paper presents commonly used basic connections of phase-shifting transformer, such as star/delta, extended-delta, zigzag, polygon and Scott, and gives the analyses and comparisons among them. Then, the paper focuses on 12-pulse phase-shifting transformers, and shows the possible strategies from basic connections to 12-pulse phase-shifting transformers, illustrating the evolution and its basic principles. The evolution and principle can be extended to the construction of multipulse transformers.