Hybrid drive system for transferring power from a gas turbine engine of an aircraft

An aircraft, comprising:

• a gas turbine engine including a shaft;
• a power takeoff shaft that extracts power from the shaft of the gas turbine engine;
• a device configured to produce substantially constant power and substantially constant rotational speed when the aircraft operates at a high altitude transition point and during descent of the aircraft;
• and
• a hybrid drive system, comprising:
• a planetary gear set including a carrier, a ring gear, and a sun gear, the carrier operatively coupled to the ring gear and the sun gear, and wherein the carrier is operatively coupled to the shaft of the gas turbine engine;
• a first motor-generator drivingly coupled to the sun gear;
• and
• a second motor-generator including an output operatively coupled to the device, the first motor-generator drivingly coupled to the second motor-generator by the ring gear and the sun gear, wherein the hybrid drive system is configured to transfer the power from the shaft into the substantially constant power and the substantially constant speed at the output of the second motor-generator when the gas turbine engine operates at a flight idle during the high altitude transition point and the descent of the aircraft and the second motor-generator transfers additional shaft power to the first motor-generator during a high altitude transition point and a descent of the aircraft, and wherein the first motor-generator transfers additional shaft power to the second motor-generator during takeoff, climb, or cruise of the aircraft.

A method for powering a device by a gas turbine engine during a high altitude transition point and during descent of an aircraft, the method comprising:

• extracting power from a shaft of the gas turbine engine by a power takeoff shaft, wherein the power takeoff shaft is drivingly coupled to a carrier of a planetary gear set;
• driving a first motor-generator by a sun gear of the planetary gear set, wherein the carrier is operatively coupled to the sun gear;
• coupling the first motor-generator to a second motor-generator by a ring gear and the sun gear;
• transferring substantially constant power and substantially constant speed from an output of the second motor-generator to a device when the gas turbine engine operates at a flight idle during the high altitude transition point and the descent of the aircraft;
• transferring additional shaft power from the second motor-generator to the first motor-generator during the high altitude transition point and the descent of the aircraft;
• and operating the first motor-generator to transfer additional shaft power to the second motor-generator during takeoff, climb, or cruise of the aircraft.