Sundstrand Corporation

Other

Sunstrand Corporation

P John Dhyanchand

Vietson M Nguyen

Chai-Nam Ng

Sunil Patel

Sampat S Shekhawat

Bryan W Dishner

Pierre S Thollot

Richard A Arbanella

Richard D Juarros

Timothy F Glennon

Vijay K Maddali

Jayant G Vaidya

Raghunath G Mokadam

Edward W Smith

Robert D Ligon

Roland W Christen

Michael D Teagardin

Vietson Nbuyen

Chai-Nan Ng

Ming Kuo

Rajhunath Mokadam

An inverter includes first and second subinverters each having inputs connected in series with the input of the other subinverter across a DC voltage and each further having a switch coupled to an output. A summing circuit includes a first input coupled to the output of the first subinverter, a second input coupled to the output of second inverter and an output. A control circuit is coupled to the subinverters and operates the switches such that a summed AC waveform is produced at the output of the summing circuit. Each switch is subjected to only a portion of the DC voltage.

High voltage inverter utilizing low voltage power switches

An inverter for converting DC power into AC power includes first and second subinverters having a plurality of controllable switches and three-phase outputs coupled to a summing transformer having wye and delta connected sets of primary windings and a set of secondary windings. The switches in the subinverters are controlled so that the subinverters produce first and second sets of pulse-width modulated subinverter waveforms which are summed by the summing transformer to produce the AC power in the secondary winding.

Stepped waveform PWM inverter

A control for an inverter having a switch which is operated in accordance with a PWM waveform having spaced rising and falling edges includes circuitry which detects the magnitude and polarity of a DC component in the AC output power produced by the inverter and an adder/subtractor which adjusts at least one of a rising and falling edge of the waveform to reduce the magnitude of the DC component.

DC content control for an inverter

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

A switching converter includes first and second controllable switches, a power source coupled to the switches and a closed flux path. First and second primary windings are mutually inductively coupled through the closed flux path and are coupled to the first and second controllable switches, respectively. The first and second switches are operated together in synchronism and a secondary winding is inductively coupled with but electrically isolated from the first and second primary windings through the closed flux path. Each switch conducts only a portion of the power produced in the secondary winding and the problems of current sharing are avoided. Also, DC content that may be produced by the switches is blocked from the output.

Switching converter and summing transformer for use therein

A summing transformer having a core structure, first primary and secondary windings wound on the core structure for establishing a rotating electromagnetic field when the first primary winding is energized, and second primary and secondary windings wound on the core structure for establishing a rotating electromagnetic field when the second primary winding is energized, and wherein the second first and second secondary windings are connected together so that voltages induced therein are added.

Electromagnetic transformer

An inverter system for inverting variable input DC and providing therefrom controlled output AC including a feedforward sensor for sensing a variable parameter of the input DC, a feedback AC sensor for sensing the controlled output AC and an inverter controller responsive to the variable parameter of the input DC and to the controlled output AC for regulating the magnitude of the controlled output AC.

Feedforward inverter phase control

This invention relates to a hybrid AC/DC power source for aircraft power generation and aircraft engine starting. The power source employs an induction motor/generator and a converter for converting high frequency AC power into separate DC and low frequency AC power for use by aircraft electrical systems. The subject invention contemplates the provision of a driver for the motor/generator comprising a circuit for providing excitation to the motor/generator when it is operating as a generator, the circuit also converting AC power produced by the generator into the high frequency AC power for use by the converter. The converter comprises a first rectifier which produces the DC power and a second rectifier and an inverter which together produce the low frequency AC power. The generator produces uncontrolled frequency AC power. Bidirectional switches operate within the circuit to invert DC excitation power to produce power for the AC excitation and to rectify output of the generator into DC. The generator can function as an induction motor to provide motive power to start the aircraft engine. Either external DC power can provide power to the induction motor via the circuit or external AC power can provide power to the induction motor via the circuit.

Induction machine based hybrid aircraft engine starting/generating power

Control pulses having a first frequency are supplied to the switches of an inverter by a controller. During initial operation of the inverter, however, a softstart circuit supplied pulses to the inverter switches of the inverter wherein the soft-start pulses have a second frequency. The second frequency is constant and higher than the first frequency.

Power generation system with soft-start circuit

An inverter for converting DC power into AC power includes first and second controllable switches which are alternately operated to produce first and second AC waveforms which are combined to form a composite AC waveform that assumes at least three different levels during a cycle of the AC power.

Stepped-waveform inverter utilizing main and auxiliary subinverters

A regulator circuit for an inverter having first and second inverter sections that develop first and second AC waveforms which are phase displaced by a variable angle .alpha. wherein the first and second AC waveforms are combined to produce AC output power includes a reference signal generator that develops a reference signal having a transition between two states at a first time, a memory storing a plurality of words each representing a value of .alpha. add a circuit for accessing the memory with a deviation signal such that the memory provides a word at an output thereof. A counter is provided and a timing circuit causes the counter to load the word at a time prior to the first time. At the first time a gating circuit provides a plurality of clock pulses to a clock input of the counter whereby the counter decrements the loaded word as the clock pulses are received by the counter. A zero detect circuit and a one-shot coupled to the output of the counter produce a synchronization signal having a transition between two states at a second time subsequent to the first time when the loaded word is decremented to a particular value. The first and second inverter sections are controlled in accordance with the reference signal and the synchronization signal so that the parameter of the AC power is maintained substantially at a particular level.

Regulation circuit for a stepped-waveform inverter

A summing transformer for a star-delta inverter having a separate secondary winding for each primary winding for use in inverting variable frequency AC power into constant frequency AC power, the transformer comprising a plurality of core sections having principal legs on which primary windings are wound and secondary legs extending between adjacent said principal legs establishing shared flux paths.

Summing transformer core for star-delta inverter having a separate

A summing transformer for a star-delta inverter having a single secondary winding for each group of primary windings for use in inverting variable frequency AC power into constant frequency AC power, the transformer comprising a plurality of core elements having principal legs on which primary windings are wound and secondary legs extending from said principal legs establishing flux paths, the legs of each core element defining apertures through which a single winding is magnetically linked to a group of primary windings.

Summing transformer for star-delta inverter having a single secondary

A cooling apparatus for windings provides the ability to cool transformer windings having many turns during high frequency use with most any coolant. The cooling apparatus comprises a thermally conductive, coolant-isolating conduit having a channel therethrough for the passage of coolant disposed between the turns of the winding in heat transfer relationship therewith.

Cooling apparatus for windings

A summing transformer includes first and second sets of primary windings, first and second sets of secondary windings inductively linked with the first and second sets of primary windings and a set of tertiary windings inductively linked with one of the first and second sets of secondary windings wherein the tertiary windigs are connected together and permit zero sequence currents to flow during a period of unbalanced load currents in the sets of secondary windings whereby the output voltages produced thereby are maintained in a substantially balanced condition during such period.

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Rockford, IL, United States of America

P John Dhyanchand