Method for regulating the speed of rotation of a propulsion device of a hybrid propulsion unit for an aircraft, in the event of a failure of the main regulation system of the heat engine of the hybrid propulsion unit

A control device for regulating the rotational speed (Np) of a propulsion device of a hybrid propulsion unit for an aircraft in the event of failure of the main regulation system of the heat engine of the hybrid propulsion unit, the hybrid propulsion unit comprising:

• the propulsion device and a main gearbox, configured to drive the propulsion device;
• the heat engine and at least one electric motor, mounted in parallel on the main gearbox, the heat engine being provided with a fuel circuit configured to transfer fuel into a combustion chamber of the heat engine;
• a main regulation system of the heat engine, configured to regulate the rotational speed of the heat engine;
• a backup regulation system of the heat engine, configured to regulate the rotational speed of the heat engine when the main regulation system fails;
• a regulation system of the electric motor, configured to regulate the rotational speed of the electric motor;
• a control system of the aircraft, configured to send a speed or power setpoint to each of the regulation systems of the heat engine and of the electric motor;
• wherein, when the main regulation system of the heat engine fails and said system is locked to a fuel flow command QCarbP*, the control device is configured to:
• send a speed setpoint NM2ref to the regulation system of the electric motor, so that the regulation system of the electric motor sends a power command PM2* to the electric motor, whereby an instantaneous power PM2m of the electric motor is obtained;
• simultaneously, send a rotational speed or power setpoint to the backup regulation system of the heat engine, so that the backup regulation system sends a fuel flow command QCarbAux* to the fuel circuit of the heat engine, the command QCarbAux* is selected so as to vary the fuel flow QCarb injected into the combustion chamber of the engine depending on whether it is desired to increase or decrease the power PM1 of the heat engine;
• and
• control the rotational speed (Np) of a propulsion device by controlling an auxiliary fuel flow QCarbAux* and the fuel flow QCarb injected into a combustion chamber of the heat engine.

A non-transitory computer readable medium for storing a computer program comprising instructions which, when the program is executed by a computer, cause the computer to perform the steps of:

• sending a speed setpoint NM2ref to an regulation system of an electric motor, so that the regulation system of the electric motor sends a power command PM2* to the electric motor, whereby an instantaneous power PM2m of the electric motor is obtained;
• simultaneously, sending a rotational speed or power setpoint to a backup regulation system of the heat engine, so that the backup regulation system sends a fuel flow command QCarbAux* to a fuel circuit of the heat engine, the command QCarbAux* is selected so as to vary the fuel flow QCarb injected into a combustion chamber of the heat engine depending on whether it is desired to vary the power PM1 of the heat engine;
• and
• controlling the rotational speed (Np) of a propulsion device by controlling an auxiliary fuel flow QCarbAux* and the fuel flow QCarb injected into a combustion chamber of the heat engine.