Abstract: An apparatus for limiting a peak voltage of a generator provides an auxiliary winding within the stationary exciter filed magnetic structure. The auxiliary winding is coupled to a controllable current source that provides a current to the auxiliary winding based upon an operating speed of the generator. The current flow is effective for moving the quiescent flux bias point of the exciter field magnetic structure for limiting the peak voltage for any operating speed of the generator.

Abstract: An aircraft is provided that includes one or more engines, an air-driven generator, and a start-circuit for operably connecting an electrical output of the air driven generator for starting one or more of the engines while the aircraft is in flight. Various embodiments also provide apparatus for cross-ship electric starting of multiple engines while the aircraft is in flight or on the ground using: an electrical output of a generator attached to another engine; on-board batteries; an on board auxiliary power unit; or power received from a ground source. A single start-converter is utilized to supply power to AC starter-motors for electric starting of the aircraft's engines. In some embodiments, the engine is soft-started with the air driven generator, by controlling blade pitch in an air driven turbine driving the air driven generator, without the use of the start converter.

Abstract: The present invention is an electrical power generating system and method of operation. An inverter (18) is responsive to a DC potential for producing a fundamental frequency alternating current output such as 400 Hz. three-phase AC including harmonics. A first harmonic suppression filter (22), coupled to the alternating current output, produces an output having reduced harmonics compared to the harmonics in the input of the inverter. An isolation transformer (61) has a primary coupled to an output (24) of the first harmonic filter, a first secondary for outputting the alternating current at the fundamental frequency, and a second secondary for also outputting the alternating current at the fundamental frequency. A first rectifier (65) is coupled to the output (63) of the first secondary and produces direct current including harmonics produced by the rectification.

Abstract: An electric power starter/generator, for converting electrical energy from a remote dc electrical power source to mechanical energy to start a turbine engine in the start mode, and for converting mechanical energy from the turbine engine to electrical energy to power utilization equipment in the generate mode, comprises a shaft for transferring rotational mechanical energy between the electric power starter/generator and the turbine engine, a permanent magnet synchronous machine having a rotor driveably coupled to the shaft and a stator. The permanent magnet synchronous machine produces polyphase ac electric power when driven as a generator, and rotational mechanical energy when driven as a motor.

Abstract: The problem of minimizing DC content in a dual converter system (18) is addressed with dual inverters (36,38) having outputs connected in parallel through an interphase transformer (42). In order to minimize DC current flow through the transformer (42) caused by non-ideal switching characteristics, a current transducer (44) senses primary current out of each inverter (36,38). Particularly, the current transducer (44) comprises a current transformer which senses the currents differentially. This sensing removes load current so that the sensed current represents interphase transformer excitation current and DC current. The excitation current is eliminated by filtering and averaging resulting in a DC signal proportional to DC current through the interphase transformer (42), which is transferred to a control processor (40) which modifies PWM patterns sent to the inverters (36,38) to reduce the DC current.

Abstract: The problem of minimizing DC content in a dual converter system (18) is addressed with dual inverters (36,38) having outputs connected in parallel through an interphase transformer (42). The outputs for each phase are connected through a neutral forming transformer (43) to develop a reference. The output voltage at each phase is sensed, filtered and averaged to develop a signal representing DC content in each of the output phase voltages. A master controller (40-1) develops switching signals for the master inverter (36) which signals are modified based on the DC content of the output phase voltages to minimize the same. A current transducer (44) for each phase senses differential current output from the master and slave inverters (36 and 38) for each phase. This signal is used to modify PWM patterns from a slave controller (40-2) for minimizing DC content through the interphase transformers (42).

Abstract: A circuit providing improved noise immunity for a first transistor including power terminals and a gate, the power terminals being connected to a power supply and to a load, and the gate being connected to receive control pulses from a pulse source for turning the first transistor on and off. A second transistor has power terminals connected across the gate and one power terminal of the first transistor, and a gate connected to a varying voltage circuit. This varying voltage circuit provides a voltage on the gate of the second transistor which varies in proportion to the spacing between the control pulses and turns on the second transistor when the spacing is greater than a preset value. The pulse source charges the varying voltage circuit during normal operation and the charge turns off the second transistor.

Abstract: Apparatus comprising a module formed by a transistor, a first diode connected in antiparallel with said transistor, and a second diode connected in series opposition with said transistor. The transistor and the diodes of the module are grouped closely together to substantially reduce parasitic inductance. Two modules are connected to form an associated pair of one phase of a three-phase inverter.

Abstract: A transistor circuit (50) in accordance with the invention includes a bipolar transistor (52) having a base and an emitter and collector coupled to a source of variable DC potential (54); an electrical load (22) coupled between the source of variable DC potential and one of the emitter and collector; a limit current generator (60), responsive to the variable DC potential, for producing a signal specifying a current limit for operating the transistor as a function of the sensed potential; a current sensor (64), coupled to the transistor circuit, for sensing current flow to the load from the source of DC potential; and a comparator (62), responsive to the current limit and the current flow to the load, for providing on an output a turnoff signal to the base of the transistor when the current flow exceeds the current limit.

Abstract: An inverter for use with a brushless generator for operating the generator in generating and starting modes includes an interphase transformer (IPT) having first and second end terminals and a mid-tap, a first subinverter coupled between a rectifier and the first end terminal of the IPT and a second subinverter. Contactors are operable in the generating mode for coupling a main generator portion armature winding to the rectifier and the second subinverter between the rectifier and the second end terminal of the IPT. The contactors are operable in the starting mode for coupling a source of power to the rectifier, the IPT mid-tap to the main generator portion armature winding and the second subinverter between the rectifier and an exciter field winding of the geneator.

Abstract: A method and apparatus are disclosed for controlling plasma etching processes in which a thin layer is etched away to expose a substrate. Coherent light is directed onto the surface being etched, so that the change in reflectivity of the surface upon exposure of the underlying substrate produces a detectable change in the characteristics of the light reflected. A derivative detector having a variable timer is provided to sample continuously the reflected light and provide a control signal in response to a predetermined change in the characteristics of the light reflected, which is used to terminate the plasma etch process before an overetch condition occurs. The method and apparatus of the invention will detect a desired end point of etching through insulation to an underlying metal substrate, through metal to an underlying insulation substrate, through one insulation type to an underlying substrate of another insulation type and through one metal to an underlying substrate of another metal.

Abstract: A system is provided for monitoring sputtering deposition parameters and through closed-loop control achieving rapid modification of the parameters to maintain or to obtain a film composition. In reactive sputtering, the sputtering chamber has individual gas pressure controllers for the various gases to be added to the chamber. A holder for a substrate on which the film is to be deposited includes a heater with adjustable control. A differentially pumped quadrupole mass analyzer interconnects with the chamber bottom to receive a sample of plasma ions, measures the ionized species existing in the plasma and generates signals related to the film composition. A controller responsive to the quadrupole analyzer actuation adjusts the pressure of the one or more reactive or non-reactive gases being provided to the chamber, and/or controls other deposition parameters, such as substrate temperature or other plasma features.