INDUCTION MOTOR TYPE ELECTRIC MOTOR VEHICLE

PURPOSE:To improve the readhesive characteristics of an induction motor type electric motor vehicle by composing to divergently vibrate the slipping speed of the vehicle when the vehicle slips. CONSTITUTION:A frequency controller 34 receives a frequency command fM obtained adding or subtracting a slip frequency fs and or from a vehicle speed signal fG detected by a tachometer generator 32 connected to a driven wheel 31, and a voltage controller 38 receives a deviation between a voltage command VR proportional to the frequency command fM and the output voltage VM of an inverter. When wheels 28 slip, the frequency of the motor 24 decreases to reduce a current, thereby decreasing the voltage drops of impedance elements 12-14. Since the output voltage of the inverter 11, however, does not almost alter, the voltage applied to the motor 14 is raised. In this manner, the apparent time constant of the generated torque of the motor is increased with respect to the abrupt decrease of the slip frequency, thereby divergently vibrate the slipping speed of the wheels 28.