PURPOSE: To safely operate a brake by controlling the sequence of the phases of output voltages of a variable voltage/variable frequency inverter so that the rotating direction of the rotating field of an induction motor coincides with that of a rotor when a brake command is dispatched to an electric motor coach.

CONSTITUTION: A DC current collected by a pantograph 1 drives an induction motor 3 through a variable voltage/variable frequency inverter 2. A pulse sensor 6 is mounted on the rotor of the motor 3 to detect a signal of the rotating direction according to which of pulse elements 6a, 6b provided, for example, so that the distances therefrom to the center of rotation are different passes earlier through the detecting point. A controller 7 outputs the sequence of the phases of the output voltages indicated by a power drive command, forward or reverse command when a power drive is operated such as a firing command of the inverter 2 as U-V-W when a forward command is operated. On the other hand, when a brake command is dispatched during running of an electric motor coach, the brake command and the sequence of the phases of the output voltage of the inverter are decided as the signal of the rotating direction fed from the sensor 6, and a firing command is outputted.