an induction motor control method includes producing a primary current as a current command which takes all constants of an induction motor into consideration . an output torque is obtained which is linear with respect to a torque command , a voltage at a dc link portion is detected , and an excitation flux command is varied by this dc voltage . this enables constant - output control to be performed irrespective of fluctuations in power supply voltage . further , a power - factor adjusting circuit is provided for adjusting the phase between voltage on the ac power supply side and current at the time of regenerative braking , so that reactive power is reduced .