Sundstrand Corporation

Hamilton Sundstrand Corporation

Thomas S Latos

Derrick I Roe

Gary L Galloway

Hassan Mansir

Michael R Hernden

Jeffrey D Nelson

Gary E Dickes

Daniel L Hughes

Kevin L Wingate

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.

Apparatus and method for limiting generator peak voltage

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.

Aircraft electrical system providing emergency power and electric

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. A second harmonic suppression filter (69), coupled to the output (67) of the rectifier, outputs direct current having reduced harmonics compared to the harmonics in the output of the fullwave rectifier.

Electrical power generating system producing alternating and direct

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. A bidirectional ac-dc power converter having a dc and an ac input/output produces variable frequency polyphase ac excitation from the dc electrical energy at the dc input/output to drive the permanent magnet synchronous machine as a brushless dc motor to generate rotational mechanical energy to start the turbine engine during the start mode. The power converter alternately produces dc electrical energy from the polyphase ac electrical energy generated by the permanent magnet synchronous machine when driven by the turbine engine during the generate mode.

Starter/generator system having multivoltage generation capability

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.

DC current control through an interphase transformer using differential

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).

DC content control in a dual VSCF converter system

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. During inactivity of the pulse source for a preset time period, the varying voltage circuit changes to the level where the second transistor turns on and shunts the first transistor, thereby preventing the first transistor from being turned on by noise signals.

Gate drive for insulated gate device

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.

Inverter switch with parallel free-wheel diodes

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.

Transistor load-line controller

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. A control unit is operable in the generating mode for operating the subinverters such that substantially constant-frequency AC power is produced at the mid-tap at the IPT and is further operable in the starting mode such that AC waveforms are delivered to the exciter field winding and the main generator portion armature windings so that the generator is operated as a motor.

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Huntley, IL, United States of America

Thomas S Latos