PURPOSE: To control each induction motor stably by distibuting power load evenly to each motor.

CONSTITUTION: A voltage reference signal 19c is fed from a current control section 19 to an amplifier 24. The amplifier 24 halves the voltage reference signal 19c and halved voltage reference signals are fed to amplifiers 25a, 25b. A current detected through a current detector 6 is fed to an amplifier 26. The amplifier 26 halves thus received current signal 6c and halved current signals are fed to amplifiers 28a, 28b. The amplifiers 28a, 28b delivers a compensation signal to the amplifiers 25a, 26b based on the difference between the halved voltage reference signal and current signal. The amplifiers 25a, 25b compensate for a voltage reference signal fed from the amplifier 24 based on compensation signals fed from the amplifiers 28a, 28b and deliver thus compensated voltage reference signals to sine wave PWM control sections 20a, 20b.