Sundstrand Corporation

Michael D Teagardin

Vietson M Nguyen

P John Dhyanchand

Chai-Nam Ng

Sunil Patel

John W Diemer

A stepped waveform inverter and control therefor utilizes the inverter itself as a divide-by-N counter in a phase-locked loop to assure precise control over the output phase and frequency of the inverter.

Stepped waveform inverter control

This invention relates to a bus configuration for a dual channel variable speed constant frequency motor/generator aircraft power system providing for both power generation and engine starting. The subject invention provides for isolation of faults which can occur in long power feeders. Further, the subject invention provides for a novel start mode of operation which allows one channel to provide power to the other channel, thereby avoiding inefficient multiple converter operation and potentially faulty power buses. The bus configuration provides for coupling a first motor/generator to a second motor/generator via a first converter to thereby allow th first motor/generator, operating as a generator, to supply variable frequency power to the first converter, the first converter supplying variable frequency power to the second motor/generator to operate the second motor/generator as a motor. A cross-start circuit is provided for selectively coupling the first channel to the second channel to allow power to be transferred between the first channel and the second channel is supplied to allow the novel start mode. The cross-start circuit completely decouples from the first and second channels when the cross-start circuit is electrically faulted, resulting in electrical isolation of the first and second channels from the fault thereby allowing continued operation of the first and second channels.

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Rockford, IL, United States of America

Michael D Teagardin