Abstract: A controller for a battery-driven DC motor controls the average motor current by switching a series-connected FET on and off with a pulse-width-modulated gate signal. Motor speed is changed by changing the duty cycle of the signal, which is generated by an oscillator. An undervoltage protection circuit senses the battery voltage and compares it with a reference system that has hysteresis. An overload protection circuit senses the motor current, integrates the sensed signal, and compares the result with a Zener reference diode that is connected in an amplifier circuit for positive feedback. The oscillator's pulse-width-modulated output, the undervoltage protection circuit's output, and the overload protection circuit's output are input to a "NOR" logic gate, whose output drives the gate of the FET.

Abstract: A vehicle multiplex system includes a controller and a number of remote stations connected to the controller by a control bus. The controller receives multiplexed signals indicative of the desired operation of loads such as headlamps and motors. In order to obtain reduced intensity headlamp operation or reduced speed of a continuous DC motor, the controller automatically connects and disconnects the headlamp or motor and a DC power source with a selected duty cycle. The period of repetition is sufficiently small to prevent perceptible flicker or fluctuation in motor speed. In this way, headlamp intensity and motor speed can be varied as desired, without increasing the hardware requirements of the system.

Abstract: A motor control system and related method are provided for phase and frequency locked operation of multiple spindle motors in a computer disk drive environment or the like, for coupling two or more disk drive units together to provide expanded data storage capability. The control system comprises a hybrid digital and analog network for producing a pulse width modulated control signal to control a disk drive spindle motor in a manner achieving frequency and phase locked relation with a reference signal. Multiple spindle motors are similarly driven in relation with the same reference signal, whereby the spindle motors are frequency and phase locked with respect to each other to permit, for example, parallel data transfer among the multiple disk drive units.

Abstract: The method uses at least one power switch having "on" and "off" states for providing, respectively, low and high impedance paths between an inductive load and a source of power and thereby controls current flow through the inductive load during a sequence of regular reoccurring time periods. The at least one power switch is switched, if in the "off" state, to the "on" state substantially at the beginning of at least some of the time periods. The method is operative during any one of a plurality of the "on" duty periods and switches the at least one power switch from the "on" state to the "off" state when a predetermined level of current flow has been reached in one of the inductive load and the at least on power switch, and switches the at least one power switch back to the "on" state independent of the occurrence of the beginning of a time period.

Abstract: The speed of a DC motor is stabilized to correspond to a reference speed by a motor driving control that is instantaneously responsive to the interval between reference pulses corresponding to the reference speed and actual observed pulses corresponding to the actual motor speed.

Abstract: A fail-safe circuit is disclosed for use with an intermittently operated d.c. motor connected by means of a circuit breaker to a power supply, wherein a control circuit provides control pulses intermittently to the motor. The fail-safe circuit includes a capacitor which is charged when the drive pulses are being applied to said motor, and is discharged when the drive pulses are not being applied to said motor. A reference voltage is generated and compared with the voltage stored on said capacitor. When the voltage on the capacitor exceeds the reference voltage, the circuit breaker is caused to interrupt the power supply to the motor.

Abstract: In a method of controlling a servomotor, a high output can be fetched from the servomotor by a motor-current control unit of a simple construction, while protecting switching elements of the control unit against excess current. The deviation between a command current (Ir) for of a plurality of winding portions constituting an armature winding of each phase and a current (Ia, Ib) flowing through each winding portion is integrated by an integrating element (9, 9'). The current (Ia, Ib) is amplified by means of a proportional element (10, 10'), and the individual currents (Ia, Ib) are controlled for substantially independent and equal values by means of one PWM control section (3) operating in response to a control signal which is obtained by adding outputs from both the elements (9.about.10').

Abstract: A control circuit for adjusting current to a direct current motor that has a free wheeling diode connected in parallel with the armature winding includes a controllable switching element connected in series with the armature winding, a comparator that has a control voltage corresponding to a desired rotational speed of the motor applied to one input of the comparator and an integrating circuit connected to the other input of the comparator. An electronic switch is connected across the integrating circuit, and the output of the comparator controls the controllable switching element and the electronic switch.