Abstract: The present invention provides a current control apparatus for a DC motor system having a motor field coil and a motor armature and driven by the power of a battery, and a chopper transistor for controlling the amount of the current supplied to the DC motor from the battery, which current control apparatus has current amplifying means for detecting the current amount at the rear end of the motor and amplifying the current value; on-off control means for comparing the input current with the current supplied from the current amplifying means and outputting an on-off control signal according to the current amount; and a microcomputer for controlling the duty value of the pulse wave of a predetermined frequency occurring in accordance with the on-off control signal from the on-off control means and controlling the on-off time of the chopper transistor.

Abstract: Current control apparatus of DC motor includes current amplifying means for detecting the current amount at the rear end of the motor and amplifying the current value; on-off control means for comparing the input current with the current supplied from the current amplifying means and outputting an on-off control signal according to the current amount; and microcomputer for controlling the duty value of the pulse wave of a predetermined frequency occurring in accordance with the on-off control signal from the on-off control means and controlling the on-off time of the chopper transistor.

Abstract: The invention is made to provide a reliable driving system by solving the problem of the conventional apparatus caused by unstable current in the chopper transistor located at the low end of the field winding and armature winding. The over drive control apparatus of the direct current series motor of the present invention, including the field winding and armature winding and driven by power from the battery, comprises a chopper transistor to which the battery is applied, and an over drive contactor connected between the chopper transistor and the field windings to switch the battery power from the chopper transistor to the field winding.