PURPOSE: To reduce a torque ripple by adding a phase advancing circuit to add a phase advancing amount to a secondary magnetic flux phase.

CONSTITUTION: A controller for a noncirculating current type cycloconverter 13 has a speed setter 1, a speed regulator 2, a magnetic flux command calculator 3, a magnetic flux regulator 4, a vector rotary unit 7, a 2-phase/3-phase coordinates converter 9, an armature current gate controller 11, a torque current regulator 22, an exciting current regulator 23, a rotor speed/phase detector 32, and a sine and cosine wave generator 33, etc. Further, it has a phase advancer-containing 3-phase current set value generator 50, and phase advancing circuits are added to the vector rotary unit and the 2-phase/3-phase converter. The phase advancing amount θ of the phase to be advanced is added to the secondary magnetic flux phase θ0, the phase angle of the secondary magnetic flux direction signal is substituted for the addition result to obtain a 3-phase AC current set value. Thus, the switching of negative and positive group converters is conducted by a simple calculation at a high speed.