System and method for operating a hybrid aircraft power plant

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.