Abstract:
A regulator (32) for a stepped-waveform inverter having first and second subinverters (70, 78) which produce waveforms having a variable phase displacement therebetween and a summing transformer (112) which sums the outputs of the subinverters includes circuitry (158) for detecting a deviation of a parameter of the AC output power produced by the inverter from a reference and circuitry (160) coupled to the detecting circuitry for deriving a phase command signal from the detected deviation. A comparator (208) compares the phase command signal with a ramp signal to obtain a comparison signal and circuitry (140, 144) 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:
Systems and methods for starting a prime mover (21), such as a gas turbine engine of an aircraft auxiliary power unit (APU), are disclosed herein whereby an electromagnetic machine (10) is operated as a motor during operation in a self starting mode to bring the prime mover (21) up to selfsustaining speed. The same electromagnetic machine (10) is thereafter operated as a generator during operation in a generating mode.
Abstract:
A control for an inverter having a switch (Q1-Q6) which is operated in accordance with a PMW waveform having spaced rising and falling edges includes circuitry (66) which detects the magnitude (76) and polarity (78) of a DC component in the AC output power produced by the inverter and an adder (64)/substractor which adjusts at least one of a rising and falling edge of the waveform to reduce the magnitude of the DC component.
Abstract:
Prior hybrid power systems which develop AC and DC power for AC and DC loads, respectively, have not separately regulated the AC and DC outputs, and hence load conditions on one of the outputs can adversely effect the loads connected to the other output. In order to overcome this problem, a hybrid power system which converts variable-frequency power developed by a brushless generator (12) 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 (20) coupled to a main generator portion armature winding (64a-64c) of the generator which converts the variable-frequency power produced by the generator into the DC power and a DC/AC converter (24) coupled to the AC/DC converter which converts the DC power into the constant-frequency AC power. A first regulator (30) 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 (32) is coupled to the DC/AC converter for controlling same in accordance with a parameter of the constant-frequency AC power to maintain such parameters substantially at regulated AC value.
Abstract:
Previously, while stepped-waveform inverters approximate a sine wave to reduce the size of filters needed at the output of such inverters, efficient and effective methods of controlling such inverters have heretofore been lacking. In order to overcome these drawbacks of previous inverters, an inverter (24) for use in a power conversion system (10) of the type used in an aircraft, for example, is provided with a first subinverter pair (30) that generates a first pair of waveforms and a second subinverter pair (32) that generates a second pair of waveforms. The two subinverter pairs (30, 32) are connected to a summing transformer (31, 33) having two pairs of primary windings (80, 92) and a plurality of secondary windings (90, 98) coupled to the primary windings (80, 92). A regulator (50, 52) is coupled to the output of the summing transformer (31, 33) and varies the phase angles between the waveforms generated by the two subinverter pairs (30, 32) based upon the voltage and current at the output of the summing transformer (31, 33) in order to regulate the voltage at the output of the summing transformer (31, 33).
Abstract:
Previously while stepped-waveform inverters approximate a sine wave to reduce the size of filters needed at the output of such inverters, efficient and effective methods of controlling such inverters have heretofore been lacking. In order to overcome these drawbacks of previous inverters, an inverter (24) for use in a power conversion system (10) of the type used in an aircraft, for example, is provided with a first subinverter pair (30) that generates a first pair of waveforms, a second subinverter pair (32) that generates a second pair of waveforms, and a third subinverter pair (34) that generates a third pair of waveforms. The three subinverter pairs (30, 32, 34) are connected to a summing transformer having first, second and third transformers (31, 33, 35). A regulator (50, 51) is coupled to the output of the summing transformer (31, 33, 35) and varies the phase angles between the three pairs of waveforms generated by the three subinverter pairs (30, 32, 34) based upon the voltage and current at the output of the summing transformer (31, 33, 35) in order to regulate the voltage at the output of the summing transformer (31, 33, 35).
Abstract:
A control for an inverter having a switch (Q1-Q6) which is operated in accordance with a PMW waveform having spaced rising and falling edges includes circuitry (66) which detects the magnitude (76) and polarity (78) of a DC component in the AC output power produced by the inverter and an adder (64)/substractor which adjusts at least one of a rising and falling edge of the waveform to reduce the magnitude of the DC component.
Abstract:
Systems and methods for starting a prime mover (21), such as a gas turbine engine of an aircraft auxiliary power unit (APU), are disclosed herein whereby an electromagnetic machine (10) is operated as a motor during operation in a self starting mode to bring the prime mover (21) up to selfsustaining speed. The same electromagnetic machine (10) is thereafter operated as a generator during operation in a generating mode.