System and method for operating a hybrid aircraft power plant
Hybrid aircraft power plants are provided together with associated systems and methods for operating such hybrid aircraft power plants. A hybrid aircraft power plant includes a thermal engine, an electric motor and one or more controllers operatively connected to the thermal engine and to the electric motor. The thermal engine and the electric motor are drivingly connected to an air mover of an aircraft via a combining gear train. The one or more controllers are configured to govern an actual output torque of the electric motor to reduce an error between a target operating speed for the air mover and an actual operating speed of the air mover, and govern an output of the thermal engine to reduce an error between a target output torque for the electric motor and the actual output torque of the electric motor.
1 . A system for controlling a hybrid power plant including an electric motor and a thermal engine drivingly connected to an air mover of an aircraft, the system comprising:
a first control system for the electric motor of the hybrid power plant, the first control system including a first controller operatively connected to the electric motor of the hybrid power plant, the first controller being configured to control an actual output torque of the electric motor to reduce a first error between a target operating speed for the air mover and an actual operating speed for the air mover; and
a second control system for the thermal engine of the hybrid power plant and configured to receive a value indicative of the actual output torque of the electric motor when the first controller is controlling the actual output torque of the electric motor and a value indicative of a target output torque for the electric motor, the second control system including a second controller operatively connected to the thermal engine of the hybrid power plant, the second controller being configured to:
when the electric motor is driving the air mover and the actual output torque of the electric motor controlled by the first controller is greater than the target output torque for the electric motor,
control the thermal engine to reduce a second error between the target output torque for the electric motor and the actual output torque of the electric motor to offload the electric motor in driving the air mover.
2 . The system as defined in claim 1 , wherein the value indicative of the target output torque for the electric motor is based on a state of charge of a battery used to drive the electric motor.
3 . The system as defined in claim 2 , wherein the first controller is configured to cause the electric motor to operate as a generator and charge the battery when the state of charge of the battery is lower than a desired state of charge for the battery.
4 . The system as defined in claim 1 , wherein the first controller is configured to cause the electric motor to operate as a generator when the target operating speed is lower than an actual operating speed of the air mover.
5 . The system as defined in claim 1 , wherein the second controller is configured to:
receive an anticipatory signal indicative of an impending load change on the air mover; and
adjust an output of the thermal engine based on the signal.
6 . A hybrid aircraft power plant comprising:
a thermal engine;
an electric motor, the thermal engine and the electric motor being drivingly connected to an air mover of an aircraft via a combining gear train; and
one or more controllers operatively connected to the thermal engine and to the electric motor, the one or more controllers being configured to:
when the electric motor is driving the air mover and an actual output torque of the electric motor is governed to reduce a first error between a target operating speed for the air mover and an actual operating speed of the air mover:
determine a second error between a target output torque for the electric motor and the actual output torque of the electric motor, the actual output torque of the electric motor being greater than the target output torque for the electric motor; and
govern an output of the thermal engine to reduce the second error between the target output torque for the electric motor and the actual output torque of the electric motor to offload the electric motor in driving the air mover.
7 . The hybrid aircraft power plant as defined in claim 6 , wherein the one or more controllers are configured to determine the target output torque based on a state of charge of a battery for powering the electric motor.
8 . The hybrid aircraft power plant as defined in claim 6 , wherein the one or more controllers are configured to cause the electric motor to operate as a generator to slow the air mover when the target operating speed for the air mover is lower than the actual operating speed of the air mover.