A motor control apparatus calculates a current command value based on a torque
command value and a rotational speed of the traction motor, and calculates a voltage
command value based on a difference between a detected current of a traction motor
and the current command value so as to reduce the difference to 0. In addition,
the motor control apparatus calculates a preferable voltage range of the traction
motor with reference to the torque command value and a motor speed, and performs
a feedback control so that the voltage value supplied to the traction motor is
within this preferable voltage range.