Abstract: 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.

Abstract: 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.

Abstract: A synchronous generator usable in both a starting mode of operation and a generating mode of operation includes a permanent magnet generator having a permanent magnet and an armature winding rotatable with respect to the permanent magnet, an exciter portion having an exciter armature winding and an exciter field winding rotatable with respect to the exciter armature winding, and a main generator portion having a main generator armature winding and a main generator field winding rotatable with respect to the main generator armature winding. An inverter is coupled to supply power to the main generator portion armature winding via a DC link during the starting mode of operation, and a controller is coupled to the DC link for controlling the magnitude of the DC link current provided to the inverter during the starting mode of operation.

Abstract: A summing transformer includes first and second sets of primary windings and first and second sets of secondary windings. The primary windings of the first set are connected in a wye configuration whereas the windings of the second set are connected in a delta configuration and the sets of primary windings are connected to form a wye-delta configuration having terminals coupled to the outputs of an inverter bridge. Each winding of the first set of secondary windings is interconnected with a winding of the second set of secondary windings. Circuitry is provided for operating the inverter bridge such that a stepped phase output waveform is produced at each of a plurality of phase outputs.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An inverter for use in a power conversion system of the type used in an aircraft, for example, includes a first subinverter pair that generates a first pair of waveforms, a second subinverter pair that generates a second pair of waveforms, and a third subinverter pair that generates a third pair of waveforms. The three subinverter pairs are connected to a summing transformer having first, second and third transformers. A regulator is coupled to the output of the summing transformer and varies the phase angles between the three pairs of waveforms generated by the three subinverter pairs based upon the voltage and current at the output of the summing transformer in order to regulate the voltage at the output of the summing transformer.

Abstract: An inverter for use in a power conversion system of the type used in an aircraft, for example, includes a first subinverter pair that generates a first pair of waveforms and a second subinverter pair that generates a second pair of waveforms. The two subinverter pairs are connected to a summing transformer having two pairs of primary windings and a plurality of secondary windings coupled to the primary windings. A regulator is coupled to the output of the summing transformer and varies the phase angles between the waveforms generated by the two subinverter pairs based upon the voltage and current at the output of the summing transformer in order to regulate the voltage at the output of the summing transformer.

Abstract: An inverter for use in a variable-speed, constant-frequency power conversion system of the type used in an aircraft, for example, includes a four subinverter pairs, each of which generates a respective set of waveforms. The four subinverter pairs are connected to a summing transformer having eight sets pairs of primary windings and eight sets of secondary windings coupled to the primary windings. A regulator is coupled to the output of the summing transformer and varies the phase angles between the waveforms generated by the four subinverter pairs based upon the voltage and current at the output of the summing transformer in order to regulate the voltage at the output of the summing transformer.

Abstract: A hybrid power system which converts variable-frequency power developed by a brushless generator into DC power which is supplied to a DC load and constant-frequency AC power which is supplied to an AC load includes an AC/DC converter coupled to a main generator portion armature winding of the generator which converts the variable-frequency power produced by the generator into the DC power and a DC/AC converter coupled to the AC/DC converter which converts the DC power into the constant-frequency AC power. A first regulator is coupled to an exciter portion field winding of the generator for supplying current thereto in dependence upon a parameter of the DC power to maintain such parameter substantially at a regulated DC value. A second regulator is coupled to the DC/AC converter for controlling same in accordance with a parameter of the constant-frequency AC power to maintain such parameter substantially at a regulated AC value.

Abstract: A regulator for a stepped-waveform inverter having first and second subinverters which produce waveforms having a variable phase displacement therebetween and a summing transformer which sums the outputs of the subinverters includes circuitry for detecting a deviation of a parameter of the AC output power produced by the inverter from a reference and circuitry coupled to the detecting circuitry for deriving a phase command signal from the detected deviation. A comparator compares the phase command signal with a ramp signal to obtain a comparison signal and circuitry operates the first and second subinverters responsive to the comparison signal to cause the phase displacement to vary in accordance with the phase command signal.

Abstract: Prior power conversion system operable in generating and starting modes have utililzed brushless generators which are suitable for only certain applications. In order to overcome this problem, a power conversion system operable in generating and starting modes utilizes a switched reluctance motor/generator which is reliable and inexpensive and which can be used in a variety of environments.

Abstract: A variable speed, constant frequency aircraft power system uses current sensing diodes to rectify the power generator output. The current flow through pairs of diodes is compared to generate phase currents to detect feeder faults.

Abstract: A power conversion system is operable in a generating mode to convert motive power developed by a prime mover into electrical power and in a starting mode to convert electrical power developed by a source of AC power into motive power for starting the prime mover. The system includes a rectifier having an output coupled to a DC link, first and second inverters, each coupled to the DC link and transformer including first and second sets of primary windings and a set of secondary windings wherein the second set of primary winding is coupled to an output of the second inverter. Contactors are provided for coupling the rectifier to the generator armature windings and the first set of primary windings to an output of the first inverter so that AC power produced by the generator is converted into DC power on the DC link and the DC power is converted into fixed frequency AC power which is developed in the set of secondary windings.