Converter and the power converter

A converter circuit section 11 for converting an AC voltage supplied to the DC voltage from the two systems of the Δ connection and Y-connection of 12-phase rectifier transformer 2, current for detecting the DC bus current output by the converter circuit section 11 comprises a detector 12, and a unbalance detector 13 for detecting that the imbalance occurs between the current outputted from the current and the Y-connection output from the detected Δ-connected by the current detector 12. It is possible to detect the unbalance that occurs and the current flowing through the diode bridge current and Y-connection side flowing in Δ connection side of the diode bridge.