Abstract: A control system for powering the direct current drive motor of an electric vehicle from a storage battery employs a semi-conductor switch to connect the battery to the motor. Speed control of the vehicle is achieved through operator control of an accelerator which provides an analog output voltage. A multi-vibrator provides a bi-valued output signal varying between 100% on time and 100% off time as a function of the accelerator output. The motor energizing switch is conditioned by this output and by the output of a circuit which compares the motor armature current to a reference value. The circuit includes protection elements so that the switch is opened when the armature current exceeds a preset maximum and is allowed to close again if the multivibrator is still in an "on" mode when the armature current decays below a lower preset value.

Abstract: A control system for powering the direct current drive motor of an electric vehicle from a storage battery employs a semi-conductor switch to connect the battery to the motor. Speed control of the vehicle is achieved through operator control of an accelerator which provides an analog output voltage. A multi-vibrator provides a bi-valued output signal varying between 100% on time and 100% off time as a function of the accelerator output. The motor energizing switch is conditioned by this output and by the output of a circuit which compares the motor armature current to a reference value. The circuit includes protection elements so that the switch is opened when the armature current exceeds a preset maximum and is allowed to close again if the multivibrator is still in an "on" mode when the armature current decays below a lower preset value.