Analysis of 12 pulse phase control AC/DC converter

In this paper, the unbalanced current in the 12-pulse phase control AC/DC converters was studied. The 12-pulse /spl Delta/-Y type AC/DC converter will keep a balanced voltage with 30/spl deg/ phase shifted at the low coupling coefficient condition, but an unbalanced current will be obtained in the 12-pulse autotransformer phase shift AC/DC converter at the low coupling coefficient condition. The theoretical phasor analysis of the unbalanced current was presented and a feedback controller was designed to overcome this problem. Finally, a 3 kW 12-pulse autotransformer phase shifted AC/DC converter was implemented to demonstrate the theoretical analysis.