A driver for driving a loading motor of a single-unit video camera-recorder. In the driver, a DC voltage supplied from a battery is boosted by a DC/DC converter, and the boosted DC voltage is supplied to the loading motor through a switch unit in which the polarity of the boosted DC voltage is switched.

A traction vehicle propulsion system comprises a d-c motor and an excitation generator for separately exciting the motor field. Current in the field winding of the excitation generator is normally controlled by a control circuit which is arranged to prevent vehicle misdirection due to control circuit failure modes wherein normal excitation current is not supplied. The control circuit comprises means responsive to an acceleration command signal for temporarily removing the field winding from the normal control circuit and for placing it instead in a biasing circuit comprising low impedance paths to the respective terminals of a direct voltage source, thereby presetting the magnetic field of the field winding in the proper direction to prevent vehicle misdirection upon acceleration from rest.

The foot-operated accelerator develops digital signals progressively larger in number as the accelerator is moved through its range from a rest position to full speed. A variable transmission has a sensor that generates digital signals progressively larger in number as the transmission is shifted from a low gear ratio to a high gear ratio. For starting the vehicle, the accelerator lower digital signals cause successive connection of a plurality of batteries in series until the full operating battery voltage is applied to the motor. Thereafter, the motor operates at a constant voltage and vehicle speed is varied by varying the gear ratio of the transmission. This is achieved by a digital comparator that compares the accelerator numbers with the transmission numbers, and a lower accelerator number causes the transmission to shift to a lower gear ratio, and a higher accelerator number causes the transmission to shift to a higher gear ratio until equilibrium is reached in each case. The motor is protected from excessive current and excessive rpm by varying the gear ratio. Regenerative braking is utilized on both coasting and manual application of the brakes.

A control apparatus for electric vehicles by using a chopper circuit which turns on or off a d-c drive motor responsive to the instruction of a microcomputer. The control apparatus of the present invention is characterized by the provision of a protection device. The protection device comprises means for generating a predetermined signal, means for adding the predetermined signal to a signal which varies depending upon the stepped-in amount of the accelerator pedal, means for comparing the added signal with an output signal of a current detector which detects a current that flows into the d-c drive motor, and means which sets the microcomputer when the output signal of the current detector is greater than the added signal and which permits the microcomputer to start again its operation after a predetermined period of time has passed.

A control for controlling the operation of a direct current motor by select application of a three phase alternating current line input of given frequency to the armature thereof through solid-state forward and reverse designated switches which are gated by select enable inputs.