Aircraft drive system

1. An aircraft drive system comprising:

a first subsystem for generating propulsion for an aircraft;

a second subsystem for generating propulsion for the aircraft;

an electrical machine comprising a first stator winding system and a second stator winding system, wherein in a normal mode of the aircraft drive system, a voltage induced in the first stator winding system is configured to be fed as electrical energy to the first subsystem and a voltage induced in the second stator winding system is configured to be fed as electrical energy to the second subsystem; and

a controller configured to establish an operating state of the aircraft drive system in such a way that the aircraft drive system is operable in the normal mode or in a motor operating state,

wherein, in the motor operating state in a manner controlled by the controller, one subsystem of the first or second subsystems is defined as a supplying subsystem and a further subsystem of the first or second subsystems is defined as a subsystem to be supplied, and electrical energy is configured to be transmitted from the supplying subsystem, via the first and second stator winding systems of the electrical machine, to the subsystem to be supplied, and

wherein, in the motor operating state, at least a portion of the electrical energy which is transmitted by the supplying subsystem to the subsystem to be supplied is configured to be fed to a battery and/or to an electric motor of the subsystem to be supplied.

2. The aircraft drive system of claim 1 , wherein the controller is configured to monitor the first subsystem and the second subsystem in respect of an occurrence of a fault in the respective subsystem and to initiate a change from the normal mode to the motor operating state when the fault is detected in the first subsystem or the second subsystem, and

wherein the respective subsystem in which the fault is present is defined as the subsystem to be supplied.

3. The aircraft drive system of claim 1 , wherein the controller is configured to determine a power P_gen(t) which is currently provided by the electrical machine, and

wherein the controller is configured to initiate a change from the normal mode to the motor operating state at a time t=T 1 only when P_gen(T 1 )≤thres_gen*P_gen_max, where P_gen_max is a maximum power provided by the electrical machine and thres_gen is a threshold value which is configured to be prespecified by the controller, where 0≤thres_gen<1/n, where n represents a number of subsystems.

4. The aircraft drive system of claim 3 , wherein the controller is configured to determine a power P_bat(t) currently provided by the battery of the supplying subsystem, and

wherein the controller is configured to initiate the transmission of electrical energy from the supplying subsystem to the subsystem to be supplied starting from a time t≥T 2 only when P_bat(T 2 )≤thres_bat*P_bat_max, where P_bat_max is a maximum power provided by the battery of the supplying subsystem and thres_bat is a threshold value configured to be prespecified by the controller, where 0≤thres_bat<1.

5. The aircraft drive system of claim 4 , wherein the controller is configured to define the threshold values thres_gen and thres_bat depending on a type of fault detected and/or depending on a current flight situation.

6. The aircraft drive system of claim 1 , wherein the first subsystem has a first propeller, a first electric motor for driving the first propeller, and a first battery,

wherein the first electric motor is configured to be supplied with electrical energy in the normal mode selectively and in a manner controlled by the controller by the first battery and/or via the first stator winding system,

wherein the second subsystem has a second propeller, a second electric motor for driving the second propeller, and a second battery, and

wherein the second electric motor is configured to be supplied with electrical energy in the normal mode selectively and in a manner controlled by the controller by the second battery and/or via the second stator winding system.

7. The aircraft drive system of claim 1 , wherein the controller is configured to determine a power P_bat(t) currently provided by the battery of the supplying subsystem, and

wherein the controller is configured to initiate the transmission of electrical energy from the supplying subsystem to the subsystem to be supplied starting from a time t≥T 2 only when P_bat(T 2 )≤thres_bat*P_bat_max, where P_bat_max is a maximum power provided by the battery of the supplying subsystem and thres_bat is a threshold value configured to be prespecified by the controller, where 0≤thres_bat<1.

8. The aircraft drive system of claim 7 , wherein the controller is configured to define the threshold value, thres_bat, depending on a type of fault detected and/or depending on a current flight situation.

9. The aircraft drive system of claim 3 , wherein the controller is configured to define the threshold value, thres_gen, depending on a type of fault detected and/or depending on a current flight situation.

10. The aircraft drive system of claim 1 , wherein the portion of the electrical energy is configured to be provided by the battery of the supplying subsystem to the battery or the electric motor of the subsystem to be supplied via the first and second stator winding systems of the electrical machine.

11. An aircraft drive system comprising:

a first subsystem for generating propulsion for an aircraft;

a second subsystem for generating propulsion for the aircraft;

an electrical machine comprising a first stator winding system and a second stator winding system, wherein in a normal mode of the aircraft drive system, a voltage induced in the first stator winding system is configured to be fed as electrical energy to the first subsystem and a voltage induced in the second stator winding system is configured to be fed as electrical energy to the second subsystem; and

a controller configured to establish an operating state of the aircraft drive system in such a way that the aircraft drive system is operable in the normal mode or in a motor operating state,

wherein, in the motor operating state in a manner controlled by the controller, one subsystem of the first or second subsystems is defined as a supplying subsystem and a further subsystem of the first or second subsystems is defined as a subsystem to be supplied, and electrical energy is configured to be transmitted from the supplying subsystem, via the first and second stator winding systems of the electrical machine, to the subsystem to be supplied,

wherein the first and second stator winding systems are arranged independently of one another, and

wherein the first and second stator winding systems are arranged such that each winding system of the first and second stator winding systems interacts in an electromagnetic manner with magnetic components of a common rotor of the electrical machine.

12. A method for operating an aircraft drive system of an aircraft, the method comprising:

generating propulsion for the aircraft by a first subsystem of the aircraft drive system;

generating propulsion for the aircraft by a second subsystem of the aircraft drive system; and

selectively operating the aircraft drive system in a normal mode or in a motor operating state,

wherein, in the normal mode, a voltage which is induced in a first stator winding system of an electrical machine of the aircraft drive system is fed as electrical energy to the first subsystem and a voltage which is induced in a second stator winding system of the electrical machine of the aircraft drive system is fed as electrical energy to the second subsystem,

wherein, in the motor operating state, one subsystem of the first or second subsystems operates as a supplying subsystem and a further subsystem of the first or second subsystems operates as a subsystem to be supplied, and electrical energy is transmitted from the supplying subsystem, via the first stator winding system and the second stator winding system of the electrical machine, to the subsystem to be supplied, and

wherein, in the motor operating state, at least a portion of the electrical energy which is transmitted by the supplying subsystem to the subsystem to be supplied is fed to a battery and/or to an electric motor of the subsystem to be supplied.

13. The method of claim 12 , wherein the first subsystem and the second subsystem are monitored in respect of an occurrence of a fault in the respective subsystem,

wherein a change from the normal mode to the motor operating state is initiated when the fault is detected in the first subsystem or the second subsystem, and

wherein the subsystem in which the fault was detected is defined as the subsystem to be supplied.

14. The method of claim 13 , wherein, when the occurrence of the fault is detected, a power P_gen(t) which is currently provided by the electrical machine is determined, and

wherein the change from the normal mode to the motor operating state is initiated at a time t=T 1 only when P_gen(T 1 )≤thres_gen*P_gen_max, where P_gen_max is a maximum power that is provided by the electrical machine and thres_gen is a prespecifiable threshold value, where 0≤thres_gen<1/n, where n represents a number of subsystems.

15. The method of claim 14 , wherein, when the occurrence of the fault is detected, a power P_bat(t) which is currently provided by the battery of the supplying subsystem is determined, and

wherein the transmission of electrical energy from the supplying subsystem to the subsystem to be supplied starting from a time t≥T 2 is initiated only when bat(T 2 )≤thres_bat*P_bat_max, where P_bat_max is a maximum power provided by the battery of the supplying subsystem and thres_bat is a prespecifiable threshold value, where 0≤thres_bat<1.

16. The method of claim 15 , wherein the prespecifiable threshold values thres_gen and thres_bat are defined depending on a type of fault detected and/or depending on a current flight situation.

17. The method of claim 13 , wherein, when the occurrence of the fault is detected, a power P_bat(t) which is currently provided by the battery of the supplying subsystem is determined, and

wherein the transmission of electrical energy from the supplying subsystem to the subsystem to be supplied starting from a time t≥T 2 is initiated only when bat(T 2 )≤thres_bat*P_bat_max, where P_bat_max is a maximum power provided by the battery of the supplying subsystem and thres_bat is a prespecifiable threshold value, where 0≤thres_bat<1.

18. The method of claim 17 , wherein the threshold value thres_bat is defined depending on a type of fault detected and/or depending on a current flight situation.

19. The method of claim 14 , wherein the threshold value thres_gen is defined depending on a type of fault detected and/or depending on a current flight situation.

20. The method of claim 12 , wherein the portion of the electrical energy is provided by the battery of the supplying subsystem to the battery or the electric motor of the subsystem to be supplied via the first and second stator winding systems of the electrical machine.