Sundstrand Corporation

Paul E Nuechterlein

Gregory I Rozman

Albert L Markunas

Vietson M Nguyen

Vijay K Maddali

Alexander Cook

Michael J Hanson

Malcolm J McArthur

Madan L Bansal

Leland E Weber

Roy S Baker

James A Shippling

Kenneth R Carr

Mario R Rinaldi

A gate drive circuit for a power transistor provides improved dielectric isolation and protection against inadvertent turn ON of the power transistor. The gate drive circuit includes a first circuit means for providing a bias power signal and a trigger pulse signal to a second circuit means in response to a control signal from an external control circuit connected to said first circuit means. The bias power signal and the trigger pulse signal are coupled from the first circuit means to the second circuit means by magnetic induction through a first and a second coupling transformer, respectively, with the first and second coupling transformers thereby providing separate pathways for coupling of the bias power signal and the trigger pulse signal between the first and second circuit means. The first and second coupling transformers further provide dielectric isolation between the first and second circuit means along each of the separate pathways.

Transistor gate drive circuit providing dielectric isolation and

An electric power generation and distribution system having a basic variable frequency distribution bus to which wide frequency variation tolerant utilization equipment is coupled and an enhanced frequency distribution bus to which wide frequency variation intolerant utilization equipment is coupled, comprises a variable speed generator driven by an external variable speed prime mover such as an aircraft engine. This generator produces output electric power having a frequency which varies with the speed at which the generator is driven. The system further comprises a converter which is electrically coupled to the generator and produces output electric power having a controlled frequency. A switching network operates to couple the generator to and decouple the converter from this enhanced bus when the frequency of the electric power produced by the generator is within a predetermined acceptable range to allow the generator to supply power thereto. The switching network also operates to decouple the generator from and couple the converter to the enhanced bus when the frequency of the electric power produced by the generator is outside this predetermined acceptable range. The converter then supplies the electric power requirements of the enhanced bus, ensuring that the utilization equipment coupled thereto is not exposed to electric power having a frequency outside an acceptable range. The converter may be operated to match the generator output waveform prior to transfer to allow a no break power transfer between the two sources.

Converter enhanced variable frequency power bus architecture

A control for a brushless generator is operable in a starting mode of operation to convert electrical power into motive power for starting a prime mover. The control applies AC power to an exciter field winding at a first frequency at the initiation of a start sequence and thereafter decreases the frequency of the power applied to the exciter field winding during the start sequence.

Starter/generator system with variable-frequency exciter control

A gate drive circuit for a power switching device having first and second power terminals and a gate terminal comprises an H-bridge rectifier having first, second, third, and fourth rectifiers, the anodes of the first and second rectifiers being mutually coupled at a midpoint to the cathodes of the third and fourth rectifiers. This midpoint is coupled to the gate terminal of the power switching device. A continuous alternating waveform generator is coupled to output selection control logic which selectively applies the waveform to either a first transformer, whose secondary is coupled to the anodes of the third and fourth rectifiers of the H-bridge for transforming the waveform from a control signal reference system to a power signal reference system, or to a second transformer, whose secondary side is coupled to the cathodes of the first and second rectifiers of the H-bridge for transforming the waveform from the control signal reference system to the power signal reference system. The output selection control logic applies the waveform to the first transformer to drive the power switching device into conduction, and alternatively to the second transformer to drive the power switching device out of conduction.

Gate drive using continuous alternating power and a diode H-bridge

A control for operating an electromagnetic machine in a starting mode of operation wherein the main armature winding of the machine receives electrical power from a controllable power source during the starting mode of operation, comprises a circuit for detecting a magnitude of a parameter of power applied to the main armature winding relative to a stationary frame of reference, a position sensor for detecting rotor position of the electromagnetic machine, a converter responsive to angular position indication for converting the detected parameter magnitude into field and torque producing components relative to a rotating frame of reference, and a circuit responsive to the field and torque producing components for controlling the power source during operation in the starting mode. This control includes an igniter for igniting a prime mover. Further, the control is operable during a first phase prior to ignition of the prime mover for causing the electromagnetic machine to provide motive power to the prime mover so as to accelerate the prime mover at a first predetermined rate, is operable during a second phase subsequent to the first phase so as to accelerate the prime mover at a second predetermined rate, is operable during this second phase for providing fuel to the prime mover to facilitate ignition thereof, and is operable during a third phase subsequent to the ignition of the prime mover so as to accelerate the prime mover at a third predetermined rate to a self-sustaining speed.

Engine starting system utilizing multiple controlled acceleration rates

The problem of providing isolated DC power in a 270 volt DC power system (10) has been resolved with the use of a DC--DC converter (44) for providing isolated DC power on busses (46-48) for powering pulsating loads (66), avionics DC loads (68) and AC loads (64). The use of the converter (44) further allows for reduction in size of ripple filters (92-94) and damper circuits (50-52).

Hybrid 270 volt DC system

A ripple reduction circuit includes a controllable switch, an impedance coupled to one of a pair of main current path electrodes of the controllable switch whereby the impedance and the switch are coupled between first and second DC conductors and gating circuitry coupled between one of the conductors and a control electrode of the controllable switch for closing the switch when AC ripple power is carried by the conductors whereby at least a portion of the AC ripple power is removed from the conductors and delivered to the impedance.

DC-link ripple reduction circuit

A snubber circuit for a power switch includes a capacitor coupled across main current path electrodes of the switch, an inductor having a first end coupled to one of the main current path electrodes of the power switch and a second end and a controllable switch having a first main current path electrode coupled to the second end of the inductor, a second main current path electrode coupled to the other main current path electrode of the power switch and a control electrode. A control circuit is coupled to the power switch and the controllable switch and turns on the controllable switch when a gating signal is commanding turn-on of the power switch and the voltage across the main current path electrodes of the power switch is above a certain level so that the capacitor is discharged through the inductor at such time. The control circuit subsequently turns off the controllable switch and turns on the power switch while the gating signal is commanding turn-on of the latter switch when the voltage across the main current path electrodes thereof falls below the certain level.

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Rockford, IL, United States of America

Paul E Nuechterlein