Abstract: An aircraft engine starting system may comprise a starter motor, a start controller for controlling the starter motor to operate with a desired torque output, and a processor for determining torque profiles for the starter motor. The processor may provide an initial torque profile responsively to ambient condition of the engine. The processor may also provide modifications to the initial torque profile responsively to temperature of the start controller.

Abstract: A starting system for aircraft engines employs power from multiple power sources. Each engine is started with a starter motor that is driven by the same multiple power sources which collectively provide starting power. As engine speed increases during each starting cycle a voltage boost is progressively provided by a boost converter. The starting system allows use of voltages higher than output voltage of the power sources while allowing the power sources to remain connected to a main aircraft power distribution bus.

Abstract: An aircraft engine starting system may comprise a starter motor, a start controller for controlling the starter motor to operate with a desired torque output, and a processor for determining torque profiles for the starter motor. The processor may provide an initial torque profile responsively to ambient condition of the engine. The processor may also provide modifications to the initial torque profile responsively to temperature of the start controller.

Abstract: A starting system for aircraft engines employs power from multiple power sources. Each engine is started with a starter motor that is driven by the same multiple power sources which collectively provide starting power. As engine speed increases during each starting cycle a voltage boost is progressively provided by a boost converter. The starting system allows use of voltages higher than output voltage of the power sources while allowing the power sources to remain connected to a main aircraft power distribution bus.

Abstract: Two spool gas turbine engines are often used to drive variable speed loads, such as an electric generator, or the fan/propeller of aircraft engines. The gas turbine engine must be designed to withstand transient speed and temperature conditions which are encountered when sudden changes to the load on the generator, fan, or propeller occur. By adding a relatively small motor/generator to the gas generator spool of the gas turbine engine, the compressor speed and airflow can be quickly adjusted to compensate for external load changes. This reduces the severity and duration of the transient conditions, resulting in decreased operation and reliability problems such as overspeed, compressor surge, and high turbine temperature. The motor/generator may also be used as an engine starting device.

Abstract: An apparatus (80) controls a synchronous machine (20) used to start an engine (300) during an engine start operation. The apparatus comprises: an exciter current control unit (84) for controlling exciter current output to the synchronous machine (20) during the engine start operation; and a main current control unit (82) for controlling main current output to the synchronous machine (20) during the engine start operation as a function of machine speed. In one implementation, the main current control unit (82) controls main current output to the synchronous machine (20) so that the synchronous machine (20) exhibits a reduced output torque during an initial torque application stage. The reduced viscous drag effects and reduced impact torque are beneficial to the engine system (100).

Abstract: A method and apparatus for executing a no-break power transfer between an electrical power generator powered by an auxiliary power unit (APU) and an electrical power generator powered by an aircraft main engine. The method comprises sending a power transfer command, a load/unload amplitude signal, and a target frequency signal from a bus power control unit to an APU electronic control unit; deriving a calculated load range for the APU at a new load and frequency operating point; and determining if the new load and frequency operating point falls within the calculated APU load range. If within range, a no-break power transfer is initiated; if not within range, a power transfer with momentary interruption is initiated.

Abstract: A start circuit controlled by an electronic control unit for providing power from one or both of a battery and TRU in parallel to a starter motor coupled to a gas turbine engine. The circuit includes contactors between the TRU and battery and a junction where the current from the TRU and battery combine. The circuit further includes two additional contactors in series between the junction and the starter motor. Voltage sensors and contactor position sensors are employed for diagnostics. A novel method of starting the engine using the start circuit contemplated by the present invention is also descibed. In this method, the start is initiated with power only from the battery. After a period of time power from the TRU is added. This method reduces the amplitude of the start motor inrush current, which has a beneficial reliability effect on the components of the start circuit.