Abstract: A motor having windings normally energizable by electric power from an AC power supply is stopped in case of an emergency such as a failure of the AC power supply. The motor has a rotor rotatably supported by magnetic bearings out of contact therewith. The windings of the motor are normally energized by a motor driver with the electric power from the AC power supply. When the AC power supply fails, a battery power supply supplies electric power to the windings of the motor to brake the rotor and also to the magnetic bearings to continuously operate the magnetic bearings. A switching controller which includes timers and logic circuit elements controls times to supply the electric power from the battery power supply to the windings of the motor and the magnetic bearings. The switching controller has timers for controlling the times.