PURPOSE: To obtain a voltage command containing no basic wave component by subtracting two phase current commands for R and S components, obtained from reverse phase real power R and imaginary power S, from two phase current commands for P and Q components obtained from instantaneous real power P and imaginary power Q of a conventional system.

CONSTITUTION: A P, Q operating circuits 101, a high pass filter 102, and a Q component current command value operating circuit 111 deliver Q component two phase current command signals Iα, Iβ to a three-phase command value operating circuit 110. An R, S operating circuit 107, a low-pass filter 108, and an R, S component current command value operating circuit 109 deliver P, Q component two phase current commands Id, Iq to the three-phase command value operating circuit 110. The three-phase command value operating circuit 110 operates each phase compensation current command signal Icu, Icv, Icw which is then fed to an amplifying circuit 104. The amplifying circuit 104 produces voltage command signals Vu, Vv, Vw to a voltage control circuit 106. The voltage control circuit 106 receives a triangular carrier voltage from a triangular wave generating circuit 105 and produces a trigger signal VG for a switching element in a PWM converter.