PURPOSE: To improve the characteristic of re-adhesion in case of coasting by changing over and controlling pattern voltage with the increase of the speed of the vehicle so as to be made higher than the minimum value among the motor voltages of a plurality of DC motors and made as the minimum voltage pattern.

CONSTITUTION: When starting power travelling, the output of a notch signal changer 6 is transmitted to a lower priority circuit 9 through a switching circuit 7 and the output 5N of a notch voltage pattern generator 5 is given when the maximum collective notches (N notches) are turned ON. The output of a generator 51 is outputted as the output of a higher priority circuit 8, and the output of the generator 51 is outputted in the circuit 9. On the other hand, each motor voltage inputted to a lower priority circuit 1 is also zero, relationship between the output of the circuit 9 and bias voltage is compared 2 and integrated 3 when car speed is slightly increased, and the output of a generator 52 is made prior through the circuit 7 by means of a counter 4 and transmitted to the circuit 9. When the vehicle coasts, meanwhile, a current control amplifier 12 is regulated by means of a voltage control amplifier 10, a voltage pattern thereof is fixed to a characteristic slightly higher than the one corresponding to present speed, and the coasting can be inhibited.