Abstract: A circuit for driving a power transistor that forms a part of an inverter circuit used in motor control in which the circuit is switched at high voltages. The motor drive circuit isolates and amplifies a control signal so as to operate the power switching transistors. The base drive circuit employs two characteristics of power transistors to derive maximum protection and maximum performance simultaneously. This control is accomplished by sensing both the collector-to-emitter voltage of the power transistor as well as the base-to-emitter voltage thereof. In an alternate embodiment described herein, a feedback circuit is also provided sensitive to collector-to-emitter voltage for shortening the try-time associated with the power transistor.

Abstract: A circuit for driving a power transistor that forms a part of an inverter circuit used in motor control in which the circuit is switched at high voltages. The motor drive circuit isolates and amplifies a control signal so as to operate the power switching transistors. The base drive circuit employs two characteristics of power transistors to derive maximum protection and maximum performance simultaneously. This control is accomplished by sensing both the collector-to-emitter voltage of the power transistor as well as the base-to-emitter voltage thereof.

Abstract: A motor pulse width modulation control technique employing gated asynchronous carrier modulation including establishing a repetitive modulation signal along with the generation of a carrier frequency signal at a frequency greater than the frequency of the modulation signal. The carrier frequency signal is gated at a gating rate less than the frequency of the carrier frequency signal so as to provide the gated carrier frequency signal. Means are provided for modulating the gated carrier frequency signal by the aforementioned repetitive modulation signal so as to provide cyclic pulse width modulation drive signal for motor control.

Abstract: D.C. motor control utilizing an input transformer with magnetic leakage and current control to allow power, whether generated occasionally or continuously from the motor (induced by load inertia and the like) to be smoothly returned back into the main A.C. power line, consistent with continuous smooth speed control (low form factor), low heating and low cost.

Abstract: Shunt motor field control for setting motor torque (and thereby controlling tension on a reeler or the like driven by the motor) comprising thyristor control gated by a comparator with a ramp-form voltage input compared to a reference level established by an operator setting of a potentiometer. The ramp-form voltage is generated by charging and discharging a capacitor and provides a spike voltage through the comparator when the reference level is exceeded. Means are provided to compensate potentiometer and capacitor tolerances to match potentiometers to the torque control setting range.