Abstract: A fault protection system provides fault protection to a permanent magnet (PM) generator. The fault protection system includes one or more overload and short-circuit protection circuits, an unbalanced protection circuit and a thermal protection circuit. The overload and short-circuit protection circuit detects both overload and short-circuit conditions by monitoring current and voltage generated at a single phase by the PM generator. The unbalanced protection circuit monitors and compares current and voltage generated associated with at least two individual phases to determine unbalanced conditions between the phases. The thermal protection circuit detects a thermal overload condition by monitoring the temperature of the PM generator.

Abstract: A fault protection system provides fault protection to a permanent magnet (PM) generator. The fault protection system includes one or more overload and short-circuit protection circuits, an unbalanced protection circuit and a thermal protection circuit. The overload and short-circuit protection circuit detects both overload and short-circuit conditions by monitoring current and voltage generated at a single phase by the PM generator. The unbalanced protection circuit monitors and compares current and voltage generated associated with at least two individual phases to determine unbalanced conditions between the phases. The thermal protection circuit detects a thermal overload condition by monitoring the temperature of the PM generator.

Abstract: A generator/starter system for starting an engine and for tapping power from the engine in order to generate electricity includes a squirrel cage rotor, a main stator winding, an auxiliary stator winding, and an excitation source. The main stator winding is magnetically coupled to the squirrel cage rotor so as to provide an AC output in response to rotation of the squirrel cage rotor and so as to rotate the squirrel cage rotor in response to an AC input. The auxiliary stator winding is magnetically coupled to the squirrel cage rotor so as to provide excitation current when the main stator winding is providing the AC output. The source of excitation current is coupled to the auxiliary stator winding.

Abstract: A generator/starter system for starting an engine and for tapping power from the engine in order to generate electricity includes a squirrel cage rotor, a main stator winding, an auxiliary stator winding, and an excitation source. The main stator winding is magnetically coupled to the squirrel cage rotor so as to provide an AC output in response to rotation of the squirrel cage rotor and so as to rotate the squirrel cage rotor in response to an AC input. The auxiliary stator winding is magnetically coupled to the squirrel cage rotor so as to provide excitation current when the main stator winding is providing the AC output. The source of excitation current is coupled to the auxiliary stator winding.

Abstract: 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.

Abstract: 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.

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: 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.

Abstract: 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.

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: A power system in accordance with the present invention includes a first inverter and a second inverter, a first transformer having a primary coupled to an output of the first inverter and a secondary coupled only magnetically to the primary of the first transformer; a second transformer having a primary coupled to the output of the second inverter and a secondary coupled only magnetically to the primary of the second transformer; a controller and a number of series circuits equal to the number of phases, each series circuit comprising the secondary windings of a corresponding phase of each transformer with a first terminal of each series circuit being coupled to a reference potential and a second terminal being a phase output for the power system.

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: The problem of sensing current through inverter switches is solved by a current transformer which has windings connected with the flyback diodes to demagnetize or reset the current transformer core. Size and weight of the transformer are minimized while avoiding a buildup of flux which would saturate the core.

Abstract: An improved converter for converting a multiple phase variable frequency AC voltage having a high degree of noise produced by a variable frequency multiple phase voltage source into a DC voltage is disclosed. Triggering pulses for a full wave recification bridge are generated by a low pass filter which filters an output signal from the multiple phase variable frequency voltage source which introduces a constant phase shift independent of frequency. A rectangular wave form is produced having a frequency synchronized with zero crossing points of the output signal from the filter. A digital phase shift compensator phase shifts the rectangular wave form to produce a timing signal having a fixed phase shift throughout the variable frequency range which compensates for the phase shift introduced by the filter.