Sundstrand Corporation

Roy S Baker

Kenneth C Kramer

Paul E Nuechterlein

David W Lefavour

A circuit to discriminate the source of harmonic distortion of the output voltage comprises voltage sensors coupled to the output terminals of a source of electric power and to a point of regulation remote from the source for sensing the output voltage waveform present at each of these locations. The circuit then utilizes these two sensed waveforms to discriminate the source of any harmonic distortion between the source of electric power and the utlization equipment. This circuit calculates the percentage total harmonic content of each of the sensed waveforms, and compares them to determine the source of distortion. If the percentage total harmonic content sensed at the point of regulation is greater than that sensed at the terminals of the source of electric power, the source of distortion is discriminated to be the utilization equipment; otherwise, the source of distortion is identified to be the source of electric power. The circuit also calculates the actual voltage difference between the two sensed voltages, and senses the current flowing in the feeders which is compared with a profile of the normal voltage drop versus connected load to generate an expected voltage drop. The two voltage difference signals are then compared. The circuit indicates the source of the harmonic distortion as the utilization equipment when the actual voltage difference deviates from the expected drop by greater than a predetermined amount.

Circuit and method for discriminating the source of waveform distortion

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 poly-phase no-break power transfer phase balance synchronization sense circuit for an electric power generation and distribution system having a present source of electric power supplying poly-phase AC electric power through a first contactor to utilization equipment and a target source of electric power connectable to supply poly-phase AC electric power to the utilization equipment through a second contactor, a transfer of the source of AC electric power from the present source to the target source being accomplished by closing the second contactor prior to opening the first contactor upon synchronization of the two sources, comprises a circuit for rectifying the poly-phase AC electric power generated by the present source, the circuit generating a first rectified output signal, a circuit for rectifying the poly-phase AC electric power generated by the target source, the circuit generating a second rectified output signal, and a circuit for differentially summing the first rectified output signal and the second rectified output signal. This summing circuit generates a synchronization error signal in response to any phase of the poly-phase AC electric power generated by the present source differing in magnitude, phase relationship, or frequency from an associated phase of the poly-phase AC electric power generated by the target source. This synchronization error signal varies in magnitude in response to the magnitude of the difference. The circuit further comprises a circuit for generating a power transfer inhibit signal when the variable magnitude of the synchronization error signal exceeds a predetermined threshold.

No-brake power transfer phase balance sychronization sense circuit and

A protection circuit for a bridge rectifier having a plurality of ac inputs coupled to a plurality of line voltages, and a dc output, comprises monitoring circuits coupled to the line voltages for monitoring the line voltages and generating sequential line-to-line voltage signals, conduction circuits coupled to the monitoring circuits for conducting that portion of each of the sequential line-to-line voltage signals having a given polarity, the conducting circuits generating sequential half wave voltage signals having a given polarity magnitude, and discriminating circuits coupled to the conducting circuits for discriminating a faulted rectifier by monitoring the given polarity magnitude of each of the sequential half wave voltage signals. The discriminating circuits generate a protection signal in response to one of the magnitudes of the sequential half wave voltages signals being less than a threshold.

Detection and isolation circuit for a failed bridge power rectifier and

A back-up electric power generating system comprises a first variable speed synchronous generator drivably coupled to a first prime mover, a second variable speed synchronous generator drivably coupled to a second prime mover, a converter having a first and a second input coupled to the first and second generators respectively, and an output, and a logic circuit in controlling communication with the converter for designating one of the first or second generators as a primary power source and one as a standby power source, exclusively. The system further comprises a primary voltage regulator selectably coupled to the primary power source generating a controlled current signal to maintain its output voltage at a given level, and a pulse exciter selectably coupled to the standby power source for verifying the operational readiness of the standby power source. This pulse exciter generates a current pulse signal to the exciter field of said standby power source and monitors the output voltage generated thereby. The converter produces a constant frequency voltage output. The method of verifying the operational readiness of a generator drivably coupled to a prime mover, the generator having an exciter field, a rotor, and a poly-phase wound stator forming an output, comprises the steps of a) providing a current pulse to the exciter field, b) monitoring the generator output, and c) indicating the operational status as ready upon detecting a voltage pulse on the generator output in response to the current pulse, or as not ready upon detecting the lack of a voltage pulse on the generator output in response to the current pulse.

Standby generator pulse excitation system and electric power generating

A system of protection which utilizes a simple circuit for the detection and isolation of single and multiple phase to phase and phase to neutral faults between a multi-phase source of electrical energy and a power conversion device driven therefrom. The circuit comprises a current transformer positioned at the neutral aspect of each phase winding of the multi-phase source of electrical energy. These current transformers sense the current generated by the source of electrical energy and produce a signal of proportional magnitude thereby. These proportional sense signals from each of the individual current transformers are transmitted to a controller which vectorially adds these signals to produce a single summed output signal. The controller monitors the percent ripple content of the summed output signal and generates an output protection signal if the percent ripple content of the monitored summed output signal exceeds a predetermined threshold value for a predetermined time interval. Means are provided responsive to the output protection signal for de-energizing the multi-phase source of electrical energy.

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Rockford, IL, United States of America

Roy S Baker