Abstract: An auxiliary power unit includes an autothermal reformer for producing a reformate from fuel; a turbine; a combustor for burning the reformate to power the turbine; a recuperator for obtaining thermal energy to improve the efficiency of the auxiliary power unit; a steam generator for using thermal energy from the recuperator to produce steam from a water supply; a condenser for recovering the water from turbine exhaust; and an electrical generator coupled to the turbine for producing electrical power. Recovered heat and water are used with the autothermal reformer to produce rapid and complete combustion of the fuel with a relatively low concentration of emissions.

Abstract: A phase/frequency estimator-based phase locked loop (PFE-PLL) may be use to obtain a phase and frequency estimation by using an algebraic summer, a gain block and a (co)sine waveform generator. The apparatus and methods of the present invention may provide the phase estimation of an input signal from which a frequency of the signal is estimated by a derivative function. Unlike conventional phase lock loop systems, which may use a multiplier to perform complex calculations on an input and a feedback signal to develop a demodulated voltage output, the present invention may use a simple algebraic summer to provide an error signal and output a phase and a frequency estimation of the input signal.

Abstract: An electrical overload protection system may be based on a solid state control system. A solid state switch may open responsively to commands for a solid-state controller. The controller may perform calculations to determine accumulated energy in a protected conductor. The calculations may be based, in part, on samplings of current in the protected conductor and ambient temperature to which the conductor may be exposed.

Abstract: A power line communication-based aircraft power distribution system may allow for both power line communication (PLC) technology and spread spectrum time domain reflectometry (SSTDR) technology to be utilized in aircraft power distribution systems to achieve key maintenance functions. Unlike conventional power distribution systems, which may, for example, use only SSTDR for fault detection, the present invention includes a hardware platform that may allow both the PLC and the SSTDR to be utilized in aircraft power distribution systems to achieve key maintenance functions, such as real time wire fault location, and cost and weight savings. Further, unlike conventional power distribution systems, which may only detect and locate damage in feeder conductor wire sections before the power is applied to the load, the power distribution system of the present invention may permit real time wire fault location.

Abstract: A filled epoxy tubesheet comprises an epoxy filled with a metal, such as aluminum flakes. Embodiments of the filled epoxy tubesheets can bend due to stress on the surface rather than crack. Embodiments of the filled epoxy tubesheet can be used to improve Air Separation Module performance by reducing or eliminating leakage through crack in the tubesheet.

Abstract: A control system for an electrical power generation system (EPGS) provides overload protection without disconnecting a generator of the EPGS from an excessive electrical load. Available engine power and current levels of the electrical load are continuously measured. A command voltage is calculated that corresponds to a voltage required to sustain with the maximum available power. Output voltage of a generator of the EPGS is controlled at the calculated command voltage so that a power limit of the engine is not exceeded during electrical overload conditions.

Abstract: A switched mode power supply (SMPS) may be operated with uncoupled output inductors. Overvoltage produced by “low-load” conditions may be controlled through use of an adaptive regulating bleeder. The bleeder may comprise a shunt regulator and a power dissipation resistor connected in parallel with a load of the SMPS. As load on the SMPS is reduced below a predetermined level, the shunt regulator may begin to conduct. Current may pass through the power dissipation resistor. Power dissipation may occur at a rate sufficient to maintain continuous conductance through an output inductor of the SMPS. During normal load operation, the shunt regulator may not conduct and inefficient dissipation of power through the resistor may be avoided.

Abstract: A generator system is configured to supply two phase excitation current from an exciter rotor to a main generator rotor. When driven by a variable speed prime mover, the generator system provides relatively constant frequency AC power by independently controlling the main rotor flux rotational speed. The generator system includes an exciter stator that induces current in the exciter rotor windings at a desired frequency and phasing. The exciter rotor windings are electrically connected to the main rotor windings to provide two-phase excitation current to the main rotor windings. Excitation is supplied to the exciter stator from an exciter controller, which controls the frequency and phasing of the exciter excitation, based on the rotational speed of the generator, to maintain a constant output frequency.

Abstract: An autotransformer for use in low frequency, high power applications that uses a stack of printed wire boards constructed of a top, inner, and bottom layer including electrical trace windings circumventing the transformer core and formed in the inner layer for direct thermal contact with a heat sink interface providing a uniform and consistent heat path down to the heat sink plate. The autotransformer further includes a board to board connection employing solder cups to electrically connect between predetermined printed wire board traces. The printed wire board autotransformer also may use a non-planar interface for thermal interface with a non-planar heat sink plate surface.

Abstract: A stub shaft of a main rotor shaft of a generator has its flange or shoulder removed from its outer portion so in the event of a bending failure of the stub shaft the resulting axial load of the stub shaft is not transmitted to the main rotor shaft. Instead of a retention plug adjacent the distal end of the inside portion of the stub shaft, a knock out plug is lightly press-fit into the main rotor shaft. In the event of a failure, the outside portion of the stub shaft enters the main rotor shaft without applying an axial load onto the main rotor shaft, moves axially and displaces the knock-out plug without exiting the main rotor shaft.

Abstract: A control system is provided for controlling varying alternating current (AC) to a load with varying resistance and inductance. A plurality of nested control loops may employ cascaded proportional controllers to provide desired control of a pulse width modulation (PWM) block to control an inverter that supplies AC power to the load. An AC feedback signal may be supplied to each proportional controller. An AC signal may be added to outputs of the proportional controllers.

Abstract: A matrix converter may be provided with AC switches that comprise bi-directional sets of semiconductor switches that are gated with a common gating link. A low loss diode-bridge based snubber may facilitate introduction of time delay between sequential operations of the bi-directional set of semiconductor switches. The matrix converter may be operated in a three-phase mode with only one gating signals for each AC switch, in contrast to prior-art matrix converters which may require use multiple gating signals for each AC switch.

Abstract: A cooling air flow regulating device for controlling the flow of cooling air to an air bearing may comprise a housing with a piston and a spring disposed within. When the pressure of the cooling air is high, the piston is forced out of the path of the cooling air and into an open position. As the pressure of the cooling air decreases, the spring forces the piston back into the path of the cooling air, effectively blocking the flow of cooling air to the air bearing. The cooling air flow regulating device of the present invention may be useful for controlling the cooling of air bearings in turbochargers of turbocharged engine, where at low engine speed, cooling air is not required for air bearings. Methods for using the cooling air flow regulating device of the present invention are also provided.

Abstract: A rigid or semi-rigid demister pad is positioned between an air turbine and an inertial water removal device such as extractor in an air conditioning system for an aircraft. The demister pad comprises packed fibers or strands whose diameter typically ranges from approximately 10 or fewer microns to approximately 280 microns. The demister is capable of catching very small droplets discharged from the air turbine that coalesce into larger droplets that exit the demister pad and enter an adjacent water removal device downstream from the pad to separate the larger water droplets from the stream of air. This avoids using a water separator containing a coalescer bag that requires frequent maintenance and is sensitive to dirt and freezing. The demister can operate at freezing temperature, is not dirt-sensitive and requires no maintenance.

Abstract: According to the features discussed herein, through a single generalized arc-fault detection algorithm, various types of series and/or parallel arc faults can be detected without any nuisance trip for either AC or DC Electric Power Systems. Running Discrete Fourier Series (RDFS) formulation for nuisance-free operation and cost-effective implementation is developed. Unlike other methods which require numerous source and load-side current and voltage measurements, only source side current is required. An arc detector may include a first detector to monitor variations of a magnitude of a fundamental component of a current, and a second detector to monitor an overload condition based in an i2t calculation.

Abstract: A bi-directional dc-dc converter is provided that may provide voltage conversion for two separate electrical power systems. The two electrical power systems may have different functions, electrical requirements and power transfer directions. The bi-directional dc-dc converter may include back-to-back bi-directional dc-dc converter circuits isolated from each other by a transformer. Multiple such dc-dc converters may be connected in parallel to increase power capability. Phase shift pulse width modulation (PWM) may be used to switch the parallel dc-dc converters so as to decrease both voltage ripple and current ripple. The number of dc-dc converters may be modified to meet the different needs of various electric power systems. A single bi-directional dc-dc converter of the invention may be employed to provide electric power conversion for multiple electric power systems, even where those systems have different power requirements and different power transfer directions.

Abstract: A control system for a PWM inverter may reduce a DC component of an output of the inverter. An output voltage signal may be attenuated with a low-pass filter to produce a signal with a high DC content. A duty cycle of an output of the low pass filter may be determined with a zero-crossing detector. A calculation may be performed to determine a magnitude of a DC offsetting voltage that may offset the DC component of the inverter output. The inverter may be commanded to produce a DC offsetting voltage with an opposite polarity from the DC component of the inverter output. The opposite polarity DC offsetting voltage may effectively cancel the DC component of the inverter output. A monitoring system may employ an alternate system for determining the level of the DC component, thus providing a desirable redundancy to the system.

Abstract: A contactor may operate to interrupt current in a circuit while the circuit is operating under load. A shunt is provided to by-pass surge power current around contacts to reduce arcing. The shunt includes a solid-state switch that may be operated in a series of pulses during movement of the contacts. The pulse control unit may detect a potential for arcing and then provide for periodic pulsing operation of the shunt. Because the solid-state switch may operate discontinuously, the contactor may be constructed with a switch that is selected on a basis of its pulse rating.

Abstract: A reduced stress rotor tip fillet that may be utilized in generators and motors as well as other types of rotating equipment is disclosed herein. The rotor tip fillet may reduce stress via an inventive fillet configuration positioned between intersecting rotor faces.

Abstract: A noise suppression wedge for a butterfly valve comprises a wedge-shaped structure having a plurality of fingers and a plurality of slots. The noise suppression wedge is positioned in contact with the butterfly plate and reduces noise by disrupting the flow through the valve.