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US 7,253,535 B2Granted
Electrical starter generator system for a gas turbine engine
AssigneeHamilton Sundstrand Corporation
InventorKurt W. Duesterhoeft
Life of this patent
Estimating the term…
Abstract
A starting system and method for a gas turbine engine applies a change in conventional starter generator torque profiles near the conclusion of the start cycle after the engine self sustaining speed and just prior to starter generator cut-out. By decreasing the applied torque to zero prior to transition from a start mode to a generator mode, both the mechanical and electrical transients are greatly decreased.
Claims14
A method of operating a starter generator system comprising the steps of:
- (1) operating a starter motor to generate an output torque;
- (2) spooling up an engine with the output torque from the starter motor;
- (3) reducing the output torque from a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output, then reducing the output torque according to a ramp function having a slope steeper than that within the constant power region to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine.
A method of starting a gas turbine engine comprising the steps of:
- (1) operating a starter motor within a constant torque region to generate an output torque;
- (2) spooling up an engine with the output torque from the starter motor in response to said step (1);
- (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output;
- (4) lighting off the gas turbine engine during said step (3);
- (5) reducing the output torque after said step (4) according to a ramp function having a slope steeper than that during said step (3) to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine.
2 more elements
A method of starting a gas turbine engine comprising the steps of:
- (1) operating a starter motor within a constant torque region to generate an output torque;
- (2) spooling up an engine with the output torque from the starter motor in response to said step (1);
- (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output;
- (4) lighting off the gas turbine engine;
- (5) reducing the output torque to approximately zero in response to the gas turbine engine reaching a self-sustaining speed in which the engine achieves an approximately zero drag torque including reducing the output torque according to the algorithm
- T
- =
- K
- n
-
- [
- n
- 2
- -
- n
- n
- 2
- -
- n
- 1
- ]
- until a speed n2 where T=Torque;
- K=Constant;
- n=speed;
- n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode;
- n2=speed at which the linear ramp function reaches zero torque.
23 more elements
A method of operating a starter generator system comprising the steps of:
- (1) operating a starter motor to generate an output torque;
- (2) spooling up an engine with the output torque from the starter motor;
- (3) reducing the output torque to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine including reducing the output torque according to a linear ramp function algorithm
- T
- =
- K
- n
- until a speed n1 where T=Torque;
- K=Constant;
- and n=speed, where n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode;
- and reducing the output torque according to the algorithm
- T
- =
- K
- n
-
- [
- n
- 2
- -
- n
- n
- 2
- -
- n
- 1
- ]
- until a speed n2 where n2=speed at which the linear ramp function reaches zero torque.
25 more elements
A method of starting a gas turbine engine comprising the steps of:
- (1) operating a starter motor within a constant torque region to generate an output torque;
- (2) spooling up an engine with the output torque from the starter motor in response to said step (1);
- (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output;
- (4) lighting off the gas turbine engine;
- (5) reducing the output torque to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine including reducing the output torque according to a linear ramp function algorithm
- T
- =
- K
- n
- until a speed n1 where T=Torque;
- K=Constant;
- and n=speed, where n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode.
9 more elements
A method of starting a gas turbine engine comprising the steps of:
- (1) operating a starter motor within a constant torque region to generate an output torque;
- (2) spooling up an engine with the output torque from the starter motor in response to said step (1);
- (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output;
- (4) lighting off the gas turbine engine;
- (5) reducing the output torque to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine including reducing the output torque according to the algorithm
- T
- =
- K
- n
-
- [
- n
- 2
- -
- n
- n
- 2
- -
- n
- 1
- ]
- until a speed n2 where T=Torque;
- K=Constant;
- n=speed;
- n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode;
- n2=speed at which the linear ramp function reaches zero torque.
23 more elements
Dependencies are inferred from the claim text.