Low pressure generator for gas turbine engine

Abstract

A gas turbine engine and methods of operation include a low pressure electric motor-generator arranged for selective operation in a generator mode to generate electrical power or a drive mode to assist rotation of a low pressure drive shaft of the engine.

What is claimed is: 
     
         1 . A system for use in an aircraft, the system comprising:
 an energy storage device;   a turbofan gas turbine engine including
 a fan configured to draw outside air into the engine, 
 a compressor coupled to the fan and configured to compress the received outside air, 
 a low pressure spool including a low pressure turbine rotor and a low pressure drive shaft that couples the low pressure turbine rotor to the fan, 
 a low pressure motor-generator coupled between the fan and the compressor to generate a flow of electric power from rotation of the low pressure turbine rotor and to drive rotation of the low pressure drive shaft, 
 a high pressure spool including a high pressure turbine rotor and a high pressure drive shaft that couples the high pressure turbine rotor to the compressor, and 
 a high pressure motor-generator coupled to an auxiliary shaft to generate a flow of electric power from rotation of the high pressure turbine rotor and to drive rotation of the high pressure drive shaft; and 
   a power controller electrically coupled to control a flow of electric power between the engine, the energy storage device, and one or more electric power consumption devices of the aircraft, the power controller being configured to, in response to the high pressure spool and the low pressure spool operating in a steady state operating mode, control to distribute at least a portion of the flow of electric power generated by the low pressure motor-generator to each of the energy storage device and the one or more electric power consumption devices.   
     
     
         2 . The system of  claim 1 , wherein operating in the steady state operating mode includes withholding providing electrically-driven force of rotation to the low pressure drive shaft and the high pressure drive shaft. 
     
     
         3 . The system of  claim 1 , where the power controller is configured to, in response to a fuel efficiency of at least one of the low pressure spool and the high pressure spool being less than a threshold, at least one of:
 control to distribute the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to adjust a present operating point of a compressor along a pressure-ratio/fuel-flow operating curve of the compressor to cause the fuel efficiency of the high pressure spool to increase, and   control to distribute the flow of electric power generated by the high pressure motor-generator to drive the low pressure motor-generator to adjust the present operating point of the compressor along the pressure-ratio/fuel-flow operating curve of the compressor to cause the fuel efficiency of the low pressure spool to increase.   
     
     
         4 . The system of  claim 3 , wherein the power controller is configured to, in response to a difference between a present operating point of the compressor and a surge operating point of the compressor being less than a threshold, control to distribute at least a portion of the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to assist rotation of the high pressure drive shaft to reduce an electric load applied the pressure spool to cause the difference between the present operating point of the compressor and the surge operating point of the compressor to increase. 
     
     
         5 . The system of  claim 4 , wherein the power controller is configured to, in response to a present operating condition of the aircraft being an in-flight restart condition, control to distribute at least a portion of the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to cause the engine to restart in-flight. 
     
     
         6 . The system of  claim 5 , wherein the power controller is configured to, in response to a present operating condition of the aircraft being an in-flight restart condition, control to distribute at least a portion of the flow of electric power from the energy storage device to the high pressure motor-generator to drive the high pressure motor-generator to cause the engine to restart in-flight. 
     
     
         7 . The system of  claim 1 , wherein the power controller is configured to, in response to a power of the engine being less than a predefined threshold, control to distribute at least a portion of the flow of electric power to drive the low pressure motor-generator to rotate the low pressure spool to generate at least a portion of thrust power used to propel the aircraft. 
     
     
         8 . The system of  claim 7 , wherein the at least a portion of the flow of electric power is from the energy storage device. 
     
     
         9 . The system of  claim 8 , wherein the power controller is configured to, in response to the engine being turned off, control to distribute at least a portion of the flow of electric power to drive the low pressure motor-generator to rotate the fan to induce an air flow in the engine. 
     
     
         10 . The system of  claim 9 , wherein the engine is turned off in response to one of a first temperature of the engine or a second temperature of a lubricant of the engine being greater than a predefined threshold. 
     
     
         11 . A method for use in an aircraft, the method comprising:
 controlling, by a power controller, in response to a high pressure spool and a low pressure spool of a turbofan gas turbine engine operating in a steady state operating mode, to distribute at least a portion of a flow of electric power generated by a low pressure motor-generator to each of an energy storage device and one or more electric power consumption devices of the aircraft, wherein the low pressure spool includes a low pressure turbine rotor and a low pressure drive shaft that couples the low pressure turbine rotor to a fan of the engine, wherein the fan is coupled to a compressor of the engine and is configured to draw outside air into the engine to be compressed by the compressor, wherein the low pressure motor-generator is coupled between the fan and the compressor to generate a flow of electric power from rotation of the low pressure turbine rotor and to drive rotation of the low pressure drive shaft, wherein the high pressure spool includes a high pressure turbine rotor and a high pressure drive shaft that couples the high pressure turbine rotor to the compressor, and wherein the engine includes a high pressure motor-generator coupled to an auxiliary shaft to generate a flow of electric power from rotation of the high pressure turbine rotor and to drive rotation of the high pressure drive shaft, wherein operating in the steady state operating mode includes withholding providing electrically-driven force of rotation on the low pressure drive shaft and the high pressure drive shaft; and   in response to a present operating condition of the aircraft being an in-flight restart condition, controlling to distribute at least a portion of the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to cause the engine to restart in-flight.   
     
     
         12 . The method of  claim 11 , further comprising, in response to a fuel efficiency of at least one of the low pressure spool and the high pressure spool being less than a threshold, at least one of:
 controlling to distribute the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to adjust a present operating point of a compressor along a pressure-ratio/fuel-flow operating curve of the compressor to cause the fuel efficiency of the high pressure spool to increase, and   controlling to distribute the flow of electric power generated by the high pressure motor-generator to drive the low pressure motor-generator to adjust the present operating point of the compressor along the pressure-ratio/fuel-flow operating curve of the compressor to cause the fuel efficiency of the low pressure spool to increase.   
     
     
         13 . The method of  claim 12 , further comprising, in response to a difference between a present operating point of the compressor and a surge operating point of the compressor being less than a threshold, controlling to distribute at least a portion of the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to assist rotation of the high pressure drive shaft to reduce an electric load applied the pressure spool to cause the difference between the present operating point of the compressor and the surge operating point of the compressor to increase. 
     
     
         14 . The method of  claim 13 , further comprising, in response to a present operating condition of the aircraft being an in-flight restart condition, controlling to distribute at least a portion of the flow of electric power from the energy storage device to the high pressure motor-generator to drive the high pressure motor-generator to cause the engine to restart in-flight, and
 in response to a power of the engine being less than a predefined threshold, controlling to distribute at least a portion of the flow of electric power to drive the low pressure motor-generator to rotate the low pressure spool to generate at least a portion of thrust power used to propel the aircraft, wherein the at least a portion of the flow of electric power is from the energy storage device.   
     
     
         15 . The method of  claim 11 , further comprising, in response to the engine being turned off, controlling to distribute at least a portion of the flow of electric power to drive the low pressure motor-generator to rotate the fan to induce an air flow in the engine, and wherein the engine is turned off in response to one of a first temperature of the engine or a second temperature of a lubricant of the engine being greater than a predefined threshold. 
     
     
         16 . A system comprising:
 turbofan gas turbine engines adapted for use in an aircraft;   a low pressure motor-generator mounted on a low pressure drive shaft and configured to operate in one of a generation mode to generate electric power from driven rotation of a low pressure turbine rotor and a drive mode to electrically drive rotation of the low pressure drive shaft;   a high pressure motor-generator configured to operate in one of a generation mode to generate electric power from driven rotation of a high pressure turbine rotor and a drive mode to electrically drive rotation of a high pressure drive shaft; and   a power controller including at least one processor for executing instructions stored on memory, wherein the power controller is electrically coupled to control the low pressure motor-generator and the high pressure motor-generator, and wherein the power control module is configured to, in response to operating conditions being an in-flight restart, operate the low pressure motor-generator in the generation mode and operate the high pressure motor-generator in the drive mode to assist restart of one of the turbofan gas turbine engines.   
     
     
         17 . The system of  claim 16 , wherein each of the turbofan gas turbine engines includes
 a high pressure spool including a compressor rotor, the high pressure drive shaft extending along an axis and rotationally coupling the compressor rotor to receive driven rotation about the axis from the high pressure turbine rotor, and   a low pressure spool including a fan rotor, the low pressure drive shaft extending along an axis and rotationally coupling the fan rotor to receive driven rotation about the axis from the low pressure turbine rotor, wherein the power controller is configured to, in response to the high pressure spool and the low pressure spool operating in a steady state operating mode, control to distribute at least a portion of the flow of electric power generated by the low pressure motor-generator to each of an energy storage device and a one or more electric power consumption devices of the aircraft.   
     
     
         18 . The system of  claim 17 , wherein the power controller is configured to, in response to a fuel efficiency of at least one of the low pressure spool and the high pressure spool being less than a threshold, at least one of:
 control to distribute the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to adjust a present operating point of a compressor along a pressure-ratio/fuel-flow operating curve of the compressor to cause the fuel efficiency of the high pressure spool to increase, and   control to distribute the flow of electric power generated by the high pressure motor-generator to drive the low pressure motor-generator to adjust the present operating point of the compressor along the pressure-ratio/fuel-flow operating curve of the compressor to cause the fuel efficiency of the low pressure spool to increase.   
     
     
         19 . The system of  claim 16 , wherein the power controller is configured to, in response to a difference between a present operating point of the compressor and a surge operating point of the compressor being less than a threshold, control to distribute at least a portion of the flow of electric power generated by the low pressure motor-generator to the high pressure motor-generator to drive the high pressure motor-generator to assist rotation of the high pressure drive shaft to reduce an electric load applied the pressure spool to cause the difference between the present operating point of the compressor and the surge operating point of the compressor to increase. 
     
     
         20 . The system of  claim 16 , wherein the power controller is configured to, in response to a power of an engine the aircraft being less than a predefined threshold, control to distribute at least a portion of the flow of electric power to drive the low pressure motor-generator to generate at least a portion of thrust power used to propel the aircraft, and
 in response to the engine being turned off, control to distribute at least a portion of the flow of electric power to drive the low pressure motor-generator to induce an air flow in the engine, wherein the engine is turned off in response to one of a first temperature of the engine or a second temperature of a lubricant of the engine being greater than a predefined threshold.