Electric propulsion unit for an aircraft

Abstract

An electric drive unit (1A, 1B) for an aircraft (2) comprises an electric machine (10A, 10B) with at least one stator (100A, 100B) and at least one rotor (101A, 101B) rotatable relative to it about an axis of rotation (D), wherein the electric machine (10A, 10B) has several sub-machines (M1-M4) each with an electrical winding system (W1-W4), wherein the winding systems (W1-W4) can be energized independently of each other to set the at least one rotor (101A, 101B) into rotation about the axis of rotation (D), wherein the power of an energization of the winding systems (W1-W4) can be adjusted differently from each other.

Description

[0001] The present disclosure relates in particular to an electric drive unit for an aircraft, to an aircraft and to a method for controlling an electric drive unit.

[0002] Aircraft are powered by a wide variety of propulsion systems. Internal combustion engines, such as piston engines or gas turbine engines, enable long ranges and high speeds. In contrast, propulsion systems with one or more electric motors allow the use of sustainably generated energy and are often particularly low-maintenance and quiet. Advances in battery and fuel cell technology are constantly expanding the applications of electric propulsion.

[0003] For electric drive units, continuous improvement of various target parameters can be pursued, such as service life, power density, and / or design complexity. However, such objectives sometimes conflict with one another.

[0004] During operation, components in electric drive units typically heat up. To dissipate this heat, cooling systems may be used, which can sometimes be complex in design. Such cooling systems can be based on air cooling or liquid cooling.

[0005] The task is to provide an improved electric propulsion unit for an aircraft.

[0006] According to one aspect, an electric propulsion unit for an aircraft is specified. The electric propulsion unit comprises an electric machine with at least one stator and at least one rotor rotatable about an axis of rotation relative to the stator. The electric machine has several sub-machines, each with an electrical winding system. The winding systems can be energized independently of one another to set the at least one rotor into rotation about the axis of rotation. It is provided that the power supplied to the winding systems can be adjusted independently of one another.

[0007] The electric drive unit may also include a control unit (or a control system with several control units) which is designed to adjust the electrical power supplied to each of the individual winding systems differently from one another.

[0008] The multiple sub-machines allow, for example, in the event of a short circuit in a coil of one of the winding systems, one of the sub-machines can be switched off while the others continue to operate. Thus, even in the case of such defects, the operation of the electric drive unit can be maintained, for example, to ensure a safe landing of the aircraft. In this way, the probability of a complete loss of power can be significantly reduced, which in turn greatly improves safety. By individually controlling or regulating the power supplied to each of the winding systems (e.g., based on the respective temperature value of the corresponding sub-machine), local temperature differences can be compensated for. Such temperature differences can occur, for example,Temperature differences can arise during operation due to one or more of the following situations: the angle of attack of the outside air used for cooling (especially during takeoff and climb of the aircraft), crosswinds, flight with a yaw angle (e.g., in the event of a failure of one of two propulsion units), turbulence or flow caused by the operation of adjacent propulsion units, and turbulence during a vertical takeoff or landing. Such temperature differences can also result, for example, from one or more of the following changes: a local blockage of one of several flow paths for cooling fluid, e.g., by foreign matter ingress, a local covering of heat sink surfaces, or locally deteriorated heat conduction.Temperature differences can arise due to aging processes or material defects, manufacturing tolerances, or turbulence or flow caused by obstacles located near the aircraft. Furthermore, such temperature differences can also result from one or more of the following structural features: serial cooling of the sub-machines, in which the coolant (e.g., liquid or gaseous) is already heated after flowing through the first sub-machine. In such situations, changes, and conditions, the temperature-dependent power control of the sub-machines proposed here makes it possible to operate the sub-machines at different power levels, ensuring that they all maintain a homogeneous temperature.Furthermore, even with a homogeneous temperature distribution across all sub-machines, it is possible to intentionally operate one or more of them at a higher or lower power output than the others, thus preparing the electric drive unit for future inhomogeneous conditions. This maximizes power density while improving service life and reliability without significantly increasing structural complexity. In this way, an improved electric drive unit can be achieved. The sub-machines can be identical in construction. The electrical current supply to each sub-machine is different from zero. The electrical power supplied to each winding system is greater than zero. Each sub-machine is therefore operated, but at least one will operate at a different (electrical and consequently mechanical) power output.

[0009] The control unit (or system) can be configured to adjust the power supplied to each individual winding system based on the respective temperature value of the respective sub-machine. This allows, for example, a response to differing temperatures between the sub-machines.

[0010] The temperature value indicates, for example, the temperature of a coil in the winding system. Furthermore, the temperature value can indicate the temperature of a cooling fluid, such as a coolant or cooling air. It can also indicate the temperature of a power supply unit (e.g., an inverter) that supplies power to the respective sub-machine. This allows for precise power settings. The control unit (or system) can be configured to periodically record the respective temperature values. The temperature sensors can be positioned at corresponding locations on the various sub-machines.

[0011] The electric drive unit can also include several temperature sensors, each measuring one of the temperature values. This allows for high accuracy. One or more temperature sensors can be provided for each sub-machine.

[0012] For example, the temperature sensors are located on, and especially inside, the respective sub-machine. This allows for simple setup and easy measurement, e.g., via resistance measurement. However, it is also possible to perform a measurement using, for example, an infrared sensor or similar device.

[0013] The control unit (or system) can be configured to control or regulate the power output of the individual winding systems in such a way that the temperature values ​​of the sub-machines equalize. Such a homogeneous temperature, even under inhomogeneous conditions, enables uniform aging.

[0014] The control unit (or system) can alternatively or additionally be configured to control or regulate the power output of the individual winding systems in such a way that the temperature of at least one of the sub-machines is set to a different value than one or more, in particular all, of the other sub-machines. By bringing only a subgroup (e.g., only one) of the sub-machines to a lower temperature, it can be prepared for anticipated conditions (e.g., an imminent aircraft takeoff) in which this sub-machine is expected to be cooled less effectively than the others (or at least some of the others). Conversely, for example, only a subgroup (e.g., only one) of the sub-machines can be brought to a higher temperature, e.g., to perform local de-icing.

[0015] The control unit (or system) can be configured to detect whether the temperature reading of (at least) one of the sub-machines indicates a higher temperature than the temperature readings of the other sub-machines. In response to this detection, the control unit (or system) can be configured to adjust the current supplied to the winding system of that (at least) one sub-machine to a value lower than the current supplied to the winding systems of the other sub-machines. This allows that sub-machine to be cooled selectively.

[0016] The electric machine includes, for example, a stator to which the multiple winding systems are attached. The winding systems can be arranged so that they interact with the same magnets of the rotor during operation. This allows for a compact design.

[0017] Furthermore, the sub-machines of the electric machine can be arranged one after the other along the axis of rotation (alternatively at the same point along the axis of rotation). This allows for a greater spatial separation of the sub-machines.

[0018] The electric drive unit (or an arrangement thereof) can further comprise at least one battery configured to supply energy to each of the sub-machines. Alternatively or additionally, the electric drive unit (or an arrangement thereof) can comprise several batteries, each configured to supply energy to one of the sub-machines and configured to exchange energy with each other. If the sub-machines are supplied with different power outputs, the state of charge of separate batteries would decrease at different rates. This can be prevented by a common power supply and / or by balancing the energy between the batteries.

[0019] The individual machines are cooled by a cooling fluid, which, for example, flows through the electric drive unit in such a way that it first cools one of the individual machines and then a second. With such serial cooling, the cooling fluid is already warmed after the first machine and cannot cool the second machine as effectively. However, due to the different power outputs, a uniform temperature can still be maintained.

[0020] Each of the sub-machines can include its own power supply unit, e.g., with power electronics, and in particular its own (e.g., multi-phase) inverter to supply power to the respective winding system. This allows for a high level of reliability. A failure of power electronics can represent a fault event with a particularly high probability.

[0021] The inverters are, for example, arranged offset from each other around the axis of rotation. This can lead to varying degrees of cooling effectiveness between the inverters. However, the different currents applied to the winding systems allow the inverters to be brought to the same temperature.

[0022] The electric machine comprises, for example, two, three, four, or more sub-machines. This allows for a high level of reliability.

[0023] The electric drive unit may also include a propeller driven by a shaft. At least one rotor may be attached to the shaft. In vertical takeoff and landing aircraft, propellers are also called rotors or (if they are swiveling) proprotors. Such propellers are also generally referred to as propellers herein.

[0024] According to one aspect, an aircraft is specified, comprising the electric propulsion unit according to any of the configurations described herein, in particular several such electric propulsion units. Regarding the advantages, reference is made to the information above.

[0025] According to one aspect, a method for controlling an electric drive unit is specified, wherein the electric drive unit comprises: an electric machine with at least one stator and at least one rotor rotatable about an axis of rotation relative to the stator, wherein the electric machine has several sub-machines, each with an electric winding system, the winding systems being independently energized to set the at least one rotor into rotation about the axis of rotation. The method optionally includes: measuring a temperature value indicative of the respective temperature of each sub-machine. The method further includes adjusting (in particular by control or regulation), by means of (at least) a control device (or system), the power of the respective currents to the individual winding systems differently, e.g., based on the respective temperature value.Regarding the advantages, reference is again made to the information above.

[0026] Exemplary embodiments with reference to the figures will now be described. The figures show: Fig. 1 an aircraft in the form of a fixed-wing aircraft with two electric propulsion units for propelling the aircraft; Fig. 2 an aircraft during a climb; Fig. 3 an electric propulsion unit of the aircraft according to Fig. 1 with an electric machine and several inverters; Fig. 4 a representation of airflows into an air duct of the electric drive unit according to Fig. 3; Fig. 5 an air mass flow through the air duct according to Fig. 4; Fig. 6 a schematic sectional view of a basic structure of the electric machine of the electric drive unit according to Fig. 3 as an internal rotor with a stator with an iron core and with an inverter per sub-machine; Fig. 7 a perspective view of the electric drive unit according to Fig. 3; and Fig. 8 a view of an electric propulsion unit for the aircraft according to Fig. 1 with several axially staggered sub-machines.

[0027] Fig. Figure 1 shows an aircraft 2 in the form of an electrically powered airplane with a fuselage 20 and wings 21.

[0028] The aircraft 2 comprises at least one electric drive unit 1A, specifically two such electric drive units 1A. Each of the electric drive units 1A comprises a propeller 13. The driven propellers 13 generate thrust for the aircraft 2. In the present case, one of the electric drive units 1A is mounted on each of the wings 21 of the aircraft 2, specifically on a respective mounting section 210 of the wing 21, although other arrangements would also be conceivable.

[0029] In alternative configurations, the aircraft 2 comprises exactly one electric propulsion unit 1A or more than two (e.g. 3, 4 or more) electric propulsion units, each with at least one propeller 13.

[0030] The aircraft 2 here includes, by way of example, a battery 22, or alternatively or additionally another electrical energy source, such as a fuel cell, a generator, a solar cell, or the like. The battery 22 stores electrical energy for operating the electric drive units 1A. The battery 22 supplies a direct current voltage. The battery 22 supplies electrical energy to the electric drive units 1A to set the respective propellers 13 into rotation and thus propel the aircraft 2.

[0031] According to Fig. In the first step, aircraft 2 (on its wheels) rests on a level, horizontally oriented surface. A vertical axis runs perpendicular to this level surface. When aircraft 2 is on the level surface, a vertical axis Y runs parallel to the vertical axis. The two propellers 13 of the two electric drive units 1A are each rotatable about a rotational axis. For example, the two rotational axes of the propellers 13 are parallel to each other. These rotational axes are perpendicular to the vertical axis Y. The rotational axes are spaced apart from each other along a lateral axis. This lateral axis runs perpendicular to both the vertical axis Y and the rotational axes of the propellers 13.

[0032] Fig. Figure 2 shows an exemplary aircraft comprising exactly one electric propulsion unit 1A. It can be seen that the aircraft has a longitudinal axis L. At the illustrated time, the aircraft is climbing. The longitudinal axis L of the aircraft is at an angle N to the horizontal H, which extends parallel to the flat ground. As a result of this angle N, the aircraft climbs, but not at the angle N itself, rather at a climb angle S relative to the horizontal H. At the climb angle S, the aircraft flies along a trajectory T.

[0033] The difference between the angle of inclination N and the angle of climb S results in an angle of attack AoA, at which the outside air strikes the electric propulsion unit 1A. For aircraft 2 according to Fig. 1. The flow of water is applied in the appropriate manner.

[0034] Fig. Figure 3 shows one of the electric drive units 1A of aircraft 2 according to Fig. 1. The aircraft's electric propulsion unit 1A according to Fig. 2 can be built identically.

[0035] The electric drive unit 1A comprises an electric machine 10A in the form of an electric motor with a heat sink 102. The electric drive unit 1A further comprises several power supply units, here inverters 11, for supplying the electric machine 10A with a multi-phase alternating voltage. Each of the inverters 11 comprises a heat sink 112. In this case, each of the several inverters 11 is configured to provide a multi-phase (in this example, three-phase) alternating voltage.

[0036] Furthermore, the electric drive unit 1A comprises an air duct 12 with an air inlet 120 and an air outlet 121 for directing outside air to at least one component of the electric drive unit 1A. The air duct 12 extends from the air inlet 120 to the air outlet 121. In the example shown, the at least one component comprises the heat sink 102 of the electric machine 10A and the heat sinks 112 of the inverters 11. However, it should be noted that instead of an air duct, it is also possible, for example, for the heat sinks 102 and / or the heat sinks 112 to be mounted on an outside surface of the electric drive unit 1A exposed to outside airflow. The electric drive unit 1A shown also includes the propeller 13 driven by the electric machine 10A.

[0037] The propeller 13 comprises several, here by way of example three, propeller blades 130, which are mounted on a hub 131. A propeller cowling 132 covers the hub 131 and directs the outside air around the hub 131.

[0038] The air inlet 120 of the air duct 12 is located adjacent to the propeller shroud 132 (also called propeller spinner or spinner). The air inlet 120 is annular. The air inlet 120 extends around a rotational axis D of the electric machine 10A. The propeller 13 is rotatable about the rotational axis D. Ambient air flowing around the propeller shroud 132, as well as ambient air moving through areas of the propeller blades 130 adjacent to the hub 131, is directed into the air inlet 120.

[0039] Outside air, which enters the air inlet 120, flows through the air duct 12 to the air outlet 121. As it does so, the outside air flows over and through the heat sink 102 of the electric machine 10, cooling it in the process. This cools the electric machine 10. Further downstream, the outside air also flows over the heat sinks 112 of the inverters 11, cooling them as well, which in turn cools the inverters 11. Alternatively, it is possible, for example, to cool the inverters 11 first and then, downstream, the electric machine 10, or to cool the inverters 11 and the electric machine 10 separately, e.g., in parallel and / or not in the same air duct.

[0040] The air duct 12 runs within an engine nacelle 16. A bracket 14 is provided on the engine nacelle 16. The bracket 14 comprises several mounting sections 140. In the assembled state, the mounting sections 140 are attached to the mounting sections 210 of the aircraft 2.

[0041] The electric machine 10A generates a torque which is transmitted via a shaft 15 to the propeller 13. The shaft 15 rotates around the axis of rotation D of the electric machine 10A.

[0042] If an airflow F with an angle of attack AoA of more than 0° now flows towards the electric drive unit 1A, as in the Fig. 2 and Fig. As illustrated in Figure 3, a wind shadow forms behind propeller 13. The same applies to a negative angle of attack (AoA).

[0043] This is in the Fig. 4 and Fig. 5 illustrates. Fig. Figure 4 shows an airflow F that hits the spinner, here referred to as propeller cowl 132, at an angle of attack AoA and consequently swirls there at 12 o'clock.

[0044] Fig. Figure 5 illustrates the annular air duct 12 and, using a scale, a mass flow through the respective areas of the air duct 12. It can be seen that the mass flow in the area around 12 o'clock is significantly reduced as a result of the wind shadow and turbulence caused by shedding.

[0045] Fig. Figure 6 shows a simplified representation of the electric machine 10A of the electric drive unit 1A according to Fig. 3.

[0046] The electric machine 10A is shown here as an example of a permanent magnet synchronous machine. Fig. Figure 6 shows that the electric machine 10A is designed as an internal rotor, although an external rotor or disc rotor design is also possible. The electric machine 10A is, for example, a radial flux machine; alternatively, it could be, for instance, a transverse flux machine or an axial flux machine.

[0047] The electric machine 10A comprises a stator 100A and a rotatable rotor 101A. In this example, the stator 100A has an opening in which the rotor 101A is rotatably mounted. The stator 100A includes several electrical coils 103.

[0048] The stator 100A comprises a body in the form of an iron core 104, on which, in this example, teeth are formed that can also be referred to as stator teeth. The teeth are aligned with an air gap between the iron core 104 of the stator 100A and the rotor 101A. The teeth project radially from a ring of the iron core 104, in this case radially inwards towards the axis of rotation D, about which the rotor 101A is rotatably mounted on the stator 100A relative to the stator 100A.

[0049] The stator 100A has several electrical conductors wound around its teeth in the form of coils 103. The stator 100A is designed for multiphase operation, specifically three-phase operation, and is connected to (at least) a three-phase AC voltage with phases U, V, and W. During normal operation of the electric machine 10A, the coils 103 (or at least a portion of them) are energized with the AC voltage. In the example shown, the stator 100A is divided into several sub-machines M1-M4, each containing several coils 103. Each sub-machine M1-M4 can be supplied with an independent AC voltage (here: three-phase AC voltage). If one or more sub-machines M1-M4 fail, the remaining sub-machines M1-M4 can continue to operate.In the example shown, four sub-machines M1-M4 are provided, although a different number of sub-machines M1-M4 may also be provided, e.g. two, three or more than four.

[0050] Each of the sub-machines M1-M4 is connected to one (own) of the inverters 11, which converts a DC voltage from the battery 22 (or a respective battery or another power source) into an AC voltage (here a three-phase AC voltage).

[0051] According to Fig. 6. The sub-machines M1-M4 are arranged circumferentially offset from each other around the axis of rotation D. The subdivision of the sub-machines M1-M4 is as follows: Fig. Figure 6 illustrates this using the mutually perpendicular dashed lines drawn through the axis of rotation D. In this example, each of the sub-machines M1-M4 extends over a quarter circle around the axis of rotation D. The sub-machines M1-M4 are arranged in a ring around the axis of rotation D. In this example, the sub-machines M1-M4 are arranged at the same position along the axis of rotation D. However, it should be noted that this arrangement is only exemplary. The coils 103 of the sub-machines M1-M4 could also be arranged distributed around the entire axis of rotation D and, for example, alternate in a regular pattern. Alternatively or additionally, the sub-machines could also be arranged axially offset from one another along the axis of rotation D.

[0052] The rotor 101A comprises several magnets 105, in this case permanent magnets, to provide the magnetic flux. The magnets 105 are arranged on an outer surface of the rotor 101A. The magnets 105 are mounted on a support 106 of the rotor 101. The outer surface of the rotor 101 faces the air gap. The magnets 105 are thus aligned with the coils 103. The magnetic poles of the magnets 105 are aligned circumferentially, e.g., alternately or in the form of a Hallbach arrangement or the like.

[0053] The three-phase alternating voltages, whose phases U, V, and W are each phase-shifted by 120°, generate a rotating magnetic field in the coils 103 during normal operation. This field interacts with the permanent magnet magnetic field provided by the rotor 101A, resulting in a corresponding rotational movement of the rotor 101A relative to the stator 100A during motor operation. The electric machine 10A is intended to serve as the drive motor for the propeller 13. It is also possible for the electric machine 10A to be operated in generator mode (or to be operated solely as a generator).

[0054] Each of the inverters 11 has a housing. A heat sink 112 with cooling fins is mounted on the housing. The cooling fins are arranged in the air duct 12 and can be cooled by the outside air flowing through it.

[0055] Power components, such as electronic switches, are mounted in the housing of each inverter 11. These components dissipate their heat to the heat sink 112. Each inverter 11 contains three modules, one for each of the three phases U, V, W of a three-phase AC voltage. Each inverter 11 thus provides a separate (three-phase) AC voltage to the electric machine 10A. The electric machine 10A has a separate winding system W1-W4 for each of the (three-phase) AC voltages, electrically isolated from the others. This configuration can also be described as a multi-lane system. If one of the sub-machines M1-M4 fails, for example due to a short circuit in the corresponding winding system W1-W4, the remaining ones can continue to operate.

[0056] The housing has three AC outputs and two DC inputs. The DC inputs receive a DC voltage supplied by battery 22. The respective inverter 11 supplies the three-phase AC voltage to the electric motor 10A at the AC outputs.

[0057] It should be noted that a different number of inverters 11 and corresponding winding systems W1-W4 of the electric machine 10A could also be provided, e.g. 2, 6 or 8.

[0058] It should also be noted that the electric machine 10A can also include more than one stator 100A and / or more than one rotor 101A (which can be rotated around the axis of rotation D).

[0059] The electric machine 10A comprises, as described, several sub-machines M1-M4, shown here as an example, each with its own electrical winding system W1-W4, whereby the winding systems W1-W4 can be energized independently of one another. Each of the winding systems W1-W4 comprises several coils 103 and separate electrical lines for the multiple, here three, phases U, V, W. Each of the sub-machines M1-M4 is configured to set the (at least one) rotor 101A into rotation about the axis of rotation D.

[0060] The winding systems W1-W4 are attached to the stator 100A and arranged so that they interact with the same magnets 105 of the rotor 101A during operation.

[0061] The electric drive unit 1A also includes a control unit 18. The control unit 18 is configured to adjust the electrical power supplied to the individual winding systems W1-W4 independently of one another. One of the winding systems W1-W4 can therefore be set to a first power value (e.g., the sum of the power across the three phases), while another of the winding systems W1-W4 is set to a second power value that differs from the first power value, e.g., by more than 1%, more than 2%, more than 5%, more than 10%, or more than 20% of the first power value.

[0062] The power supply is, for example, the active power summed over all phases (U, V, W) of the respective winding system W1-W4.

[0063] In the present example, the control unit 18 is specifically designed to adjust the electrical power supplied to each of the winding systems W1-W4 based on the respective temperature value of the respective sub-machine M1-M4. This allows the sub-machines M1-M4 (e.g., the same components of the sub-machines M1-M4) to be operated at the same temperature even under different conditions, or, for example, at the temperature of one of the sub-machines M1-M4 within + / - 1%, + / - 2%, or + / - 5%.

[0064] For this purpose, the electric drive unit 1A includes several temperature sensors 17 for periodically measuring one of the temperature values ​​each. The temperature sensors 17 are each arranged on the corresponding sub-machine M1-M4.

[0065] In Fig. 6. A temperature sensor 17 is arranged on each of the winding systems W1-W4. These temperature sensors 17 are configured to measure the temperature of the respective winding systems W1-W4. Specifically, these temperature sensors 17 are each located next to a coil 103 (or within a coil 103, e.g., at the expected hotspot) of the respective winding systems W1-W4, so that the measured temperature value indicates the temperature of the respective coil 103. The control unit 18 can acquire the temperature values ​​using these temperature sensors 17.

[0066] Furthermore, the electric drive unit 1A includes a temperature sensor 17 on each of the inverters 11. These temperature sensors 17 are configured to measure the temperature of the respective inverter 11. The control unit 18 can acquire the temperature values ​​using these temperature sensors 17 (alternatively or additionally to the previously described acquisition of the temperature values). The electric drive unit 1A can also include a temperature sensor 17 for each of the sub-machines M1-M4, which measures the temperature of a cooling fluid (in this example, air) flowing out of the sub-machine M1-M4, in order to acquire the temperature values ​​in this way, either alternatively or additionally. The temperature values ​​can be acquired using a single temperature sensor 17 or using multiple temperature sensors 17, e.g., by averaging the individual measured values ​​or the like.

[0067] The control unit 18 is communicatively connected to the temperature sensors 17, e.g., via appropriate cable connections. The control unit 18 is also communicatively connected to the inverters 11, e.g., via appropriate cable connections. The control unit 18 can also be communicatively connected to the battery 22 (or batteries 22). The control unit 18 controls the inverters 11. The control unit 18 outputs the electrical power supplied by the respective inverter 11 to the respective sub-machine M1-M4. The electrical power can be the manipulated variable of a control loop, while the temperature value, for example, is the controlled variable. The reference variable is, for example, a predefined temperature, the temperature value of another of the sub-machines M1-M4, or the average of the temperature values ​​of the other sub-machines M1-M4.

[0068] The control unit 18 is, in this example, a central control unit that controls each of the sub-machines M1-M4 (each of the sub-machines M1-M4 can alternatively or additionally include its own control unit). However, it should be noted that the electric drive unit 1A could also be designed without such a central control unit and / or that the described function is not performed by a central control unit. For example, if the drive is regulated to a specific speed (e.g., each inverter receives a signal to regulate to 2000 rpm), it could be designed that inverters (or another component of the respective sub-machine) exceeding a predetermined or predefinable maximum temperature (e.g., along a ramp) are individually regulated (e.g., for every 1°C above the maximum temperature, the power is reduced by a predetermined value or percentage, e.g., 5%).The other inverters then compensate for this power loss, for example, because they are designed to continue trying to maintain the (for example) 2000 rpm.

[0069] If several batteries 22 are provided, e.g. one battery 22 for each of the sub-machines M1-M4, then these can be arranged (e.g. via a corresponding energy transfer unit) to exchange energy with each other, in particular in such a way that the charge levels of the batteries 22 remain the same with each other, even if one sub-machine M1-M4 is operated more or less strongly than the others.

[0070] Accordingly, a method for controlling the electric drive unit 1A comprises measuring an indicative temperature value for each temperature of the sub-machines M1-M4 and controlling or regulating, by means of the control unit 18, the electrical power supplied to the individual winding systems W1-W4 based on the respective temperature value.

[0071] For this purpose, the control unit 18 comprises a processor arrangement 180 and a memory arrangement 181. Computer-readable instructions are stored in the memory arrangement 181 (in this case in a non-volatile memory area), which, when executed by the processor arrangement 180, cause the control unit 18 to carry out the described procedure.

[0072] The control unit 18 is further configured to carry out the procedure in such a way that the electrical power of the individual winding systems W1-W4 is controlled or regulated so that the temperature values ​​of the sub-machines M1-M4 are equalized. For example, the control unit 18 detects that the temperature value of one of the sub-machines M1-M4, e.g., the upper sub-machine M2, indicates a higher temperature than the temperature values ​​of the other sub-machines M1-M4. If this is the case, the control unit 18, in response, adjusts the electrical power supplied to the winding system W1-W4 of this sub-machine M2 to an electrical power that is lower than the respective electrical powers supplied to the winding systems W1, W3-W4 of the other sub-machines M1, M3-M4. This equalizes the temperature of the upper sub-machine M2 with the temperatures of the other sub-machines M1, M3-M4.Should a deviation also occur among the other sub-machines M1, M3-M4, it can be compensated for in the same way. This process can be carried out continuously. Meanwhile, the control unit 18 iteratively adjusts the sum of the electrical power outputs (e.g., by increasing or decreasing them by a certain percentage) so that the electrical power, mechanical power, torque, and / or thrust requested by the electric drive unit is generated by the electric machine 10A.

[0073] Furthermore, the control unit 18 is configured to carry out the procedure in such a way that the electrical power of the individual winding systems W1-W4 is controlled or regulated so that the temperature of at least one of the sub-machines M1-M4 is set to a different value than one or more, in particular all, of the other sub-machines M1-M4. This can be used, for example, for de-icing an area or for cooling a sub-machine M1-M4 that is expected to heat up more than the other sub-machines M1-M4 during an upcoming maneuver. If, for example, a start or an ascent is to be initiated within a predetermined time, the power of one sub-machine, e.g., the upper one M2, can be reduced beforehand, while the overall power remains unchanged by increasing the power of the other sub-machines M1, M3-M4.This allows the (upper) sub-machine M2 to be cooled to a lower starting temperature, from which the start or ascent is carried out, thus preventing overheating.

[0074] If one of the sub-machines M1-M4 is cooled more than the others, e.g. by external influences or a heat sink adjacent to that sub-machine, then its electrical power can also be increased compared to the others.

[0075] As a result, a homogeneous temperature distribution of sub-machines M1-M4 can be achieved while maintaining a constant overall mechanical output of the electric drive unit 1A. This allows for an increase in the power density of the electric machine 10A, extends its service life, improves reliability, and simplifies the integration of the electric drive unit into various aircraft, as it compensates for uneven air cooling.

[0076] It should be noted that the reduction (or increase) of the power output of one of the sub-machines M1-M4 can also be implemented by modifying the slope of a ramp (e.g., a torque ramp) compared to the other sub-machines. The slopes of the remaining sub-machines are then adjusted so that a corresponding total torque (e.g., according to a ramp) is provided.

[0077] Fig. Figure 7 shows the electric drive unit 1A in a perspective view. It can be seen that the stator 100A of the electric machine 10A is surrounded externally by the annular (one-piece or multi-piece) heat sink 102. The heat sink 102 has cooling fins through which the outside air flowing through the air duct 12 flows.

[0078] Furthermore, it can be seen that (downstream of the heat sink 102) the inverters 11 are arranged around the axis of rotation D (offset from each other), in the present example at equal intervals.

[0079] Fig. Figure 8 shows another electric drive unit 1B, which can include the aircraft 2, e.g. as an alternative to or in addition to the electric drive unit 1A.

[0080] The electric drive unit 1B comprises an electric machine 10B with two sub-machines M1 and M2. The sub-machines M1 and M2 are arranged one behind the other along the axis of rotation D. The electric drive unit 1B includes two stators 100B and two rotors 101B.

[0081] The stators 100B are both fixed to a housing, the rotors 101B are both fixed to a shaft 15. A propeller 13 is driven via the shaft 15.

[0082] The sub-machines M1 and M2 each have a winding system W1 and W2, respectively, which can be independently powered by a three-phase alternating voltage, as described above, with individually and differently adjustable electrical power levels. The power levels are all of the same type, e.g., active power.

[0083] The sub-machines M1 and M2 are cooled by a cooling fluid (in this case, a coolant liquid) which flows through the electric drive unit 1B in such a way that it first cools the first sub-machine M1 of the sub-machines M1 and M2, and then cools the second sub-machine M2 of the sub-machines M1 and M2. For this purpose, the electric drive unit 1B includes a cooling system 19 with a cooling circuit. A pump 192 pumps the coolant liquid through lines 190 into the first sub-machine M1, thus cooling it. In doing so, the coolant is heated from a first temperature to a higher second temperature. Another line 190 connects the first sub-machine M1 to the second sub-machine M2. The coolant flows into the second sub-machine M2 at the second temperature and cools it. In doing so, the coolant is heated to a third temperature, which is again higher than the second temperature.The coolant is then fed through a further line 190 to a heat exchanger 191, where it is cooled back down to the initial temperature. The coolant is collected in an optional tank 193. The order of the heat exchanger 191, the tank 193, and the pump 192 may differ from that shown.

[0084] Temperature sensors 17 measure the temperature values ​​on the lines 190, indicating the first, second, and third temperatures. Additional temperature sensors 17, arranged as described above, can be provided as an alternative or supplement. The control unit 18 (not shown again here) adjusts the electrical and / or mechanical power outputs of the sub-machines M1 and M2 based on the temperature values, as described above, so that both sub-machines M1 and M2 operate at the same temperature. In this case, the first sub-machine M1 operates at a higher power output than the second sub-machine M2.

[0085] While Fig.Figure 1 illustrates aircraft 2 as a fixed-wing aircraft. It should be noted that the electric drive units 1A, 1B described herein can also be used, for example, in an aircraft designed as a VTOL aircraft. Vertical take-off and landing aircraft, such as airplanes, are referred to as VTOL aircraft, the abbreviation being derived from "Vertical Take-Off and Landing." VTOL aircraft are designed for vertical take-off and landing. One or more of the electric drive units can be pivoted relative to the fuselage of the aircraft. This allows them to be pivoted between a predominantly lift-generating position and a predominantly forward-thrusting position. The electric drive units can be mounted on the wings of the aircraft (and / or directly on the fuselage), for example.at least one (or at least two) swiveling and at least one (or at least two) non-swiveling wing per wing.

[0086] It is understood that the disclosure is not limited to the embodiments described above and that various modifications and improvements may be made without deviating from the concepts described herein. Any of the features may be used separately or in combination with any other features, provided they are not mutually exclusive, and the disclosure extends to and encompasses all combinations and subcombinations of one or more features described herein. Reference symbol list 1A, 1B electric drive unit 10A, 10B electric machine 100A, 100B Stator 101A, 101B Rotor 102 heat sinks 103 coil 104 Iron core 105 Magnet 106 carriers 11 inverters 112 heat sinks 12 air duct 120 air intake 121 Air outlet 13 propellers 130 propeller blade 131 hub 132 Propeller cowling 14 bracket 140 Assembly section 15 wave 16 Engine nacelle 17 Temperature sensor 18 Control unit 180 processor arrangement 181 Storage arrangement 19 Cooling system 190 line 191 heat exchangers 192 Pump 193 Tank 2 aircraft 20 hull 21 wings 210 Assembly section 22 Battery AoA angle of attack D axis of rotation F Airflow H Horizontal L Longitudinal axis M1-M4 Submachine N Inclination angle S climb angle T trajectory W1-W4 winding system Y vertical axis

Claims

[1] Electric drive unit (1A, 1B) for an aircraft (2), comprising an electric machine (10A, 10B) with at least one stator (100A, 100B) and at least one rotor (101A, 101B) rotatable relative to it about an axis of rotation (D), wherein the electric machine (10A, 10B) has several sub-machines (M1-M4) each with an electrical winding system (W1-W4), wherein the winding systems (W1-W4) can be energized independently of each other to cause the at least one rotor (101A, 101B) to rotate about the axis of rotation (D), wherein the power of an energization of the winding systems (W1-W4) can be adjusted differently from each other. [2] Electric drive unit (1A, 1B) according to claim 1, further comprising a control unit (18) which is configured to adjust the power of the current supply to the winding systems (W1-W4) differently from one another, wherein the control unit (18) is configured to adjust the power supply to each of the winding systems (W1-W4) based on a respective temperature value of the respective sub-machine (M1-M4). [3] Electric drive unit (1A, 1B) according to claim 2, wherein the temperature value indicates the temperature of a coil (103) of the winding system (W1-W4), a cooling fluid or an inverter (11) of the respective sub-machine (M1-M4). [4] Electric drive unit (1A, 1B) according to claim 2 or 3, further comprising several temperature sensors (17) for measuring one of the temperature values. [5] Electric drive unit (1A, 1B) according to claim 4, wherein the temperature sensors (17) are each arranged on the corresponding sub-machine (M1-M4). [6] Electric drive unit (1A, 1B) according to one of claims 2 to 5, wherein the control unit (18) is configured to control or regulate the power of the individual winding systems (W1-W4) so ​​that the temperature values ​​of the sub-machines (M1-M4) are equalized. [7] Electric drive unit (1A, 1B) according to one of claims 2 to 6, wherein the control unit (18) is configured to control or regulate the power of the individual winding systems (W1-W4) such that the temperature value of at least one of the sub-machines (M1-M4) is set to a different value than one or more of the other sub-machines (M1-M4). [8] Electric drive unit (1A, 1B) according to one of claims 2 to 7, wherein the control unit (18) is configured to detect whether the temperature value of one of the sub-machines (M1-M4) indicates a higher temperature than the temperature values ​​of the other sub-machines (M1-M4) and, in response thereto, to adjust the power of the current supply to the winding system (W1-W4) of this one sub-machine (M1-M4) to a value that is lower than the power supply to the winding systems (W1-W4) of the other sub-machines (M1-M4). [9] Electric drive unit (1A) according to one of the preceding claims, wherein the electric machine (10A) comprises a stator (100A) to which the multiple winding systems (W1-W4) are attached, wherein the winding systems (W1-W4) are arranged such that they interact with the same magnets (105) of the rotor (101A) during operation. [10] Electric drive unit (1B) according to one of the preceding claims, wherein the sub-machines (M1-M2) of the electric machine (10B) are arranged one behind the other along the axis of rotation (D). [11] Electric drive unit (1A, 1B) according to one of the preceding claims, further comprising a battery (22) which is configured to provide energy to each of the sub-machines (M1-M4) and / or several batteries (22) which are each configured to provide energy to each of the sub-machines (M1-M4) and are configured to exchange energy with each other. [12] Electric drive unit (1B) according to one of the preceding claims, wherein the sub-machines (M1-M2) are cooled by a cooling fluid which can flow through the electric drive unit (1B) in such a way that it first cools a first of the sub-machines (M1-M2) and then cools a second of the sub-machines (M1-M2). [13] Electric drive unit (1A, 1B) according to one of the preceding claims, wherein each of the sub-machines (M1-M4) comprises a multi-phase inverter (11) for powering the respective winding system (W1-W4). [14] Electric drive unit (1A, 1B) according to claim 13, wherein the inverters (11) are arranged offset from each other around the axis of rotation (D). [15] Electric drive unit (1A) according to one of the preceding claims, wherein the electric machine (10A) comprises four sub-machines (M1-M4). [16] Electric drive unit (1A, 1B) according to one of the preceding claims, further comprising a propeller (13) driven via a shaft (15), wherein the at least one rotor (101A, 101B) is attached to the shaft (15). [17] Aircraft (2) comprising the electric propulsion unit (1A, 1B) according to any one of the preceding claims. [18] Method for controlling an electric drive unit (1A, 1B), the electric drive unit (1A, 1B) comprising an electric machine (10A, 10B) with at least one stator (100A, 100B) and at least one rotor (101A, 101B) rotatable relative to it about an axis of rotation (D), wherein the electric machine (10A, 10B) comprises several sub-machines (M1-M4) each with an electrical winding system (W1-W4), wherein the winding systems (W1-W4) can be energized independently of one another to set the at least one rotor (101A, 101B) into rotation about the axis of rotation (D), the method comprising: - Measure one indicative temperature value for each of the respective temperatures of the sub-machines (M1-M4) and - Adjusting, by means of at least one control unit (18), the power of an energization of the individual winding systems (W1-W4) based on the respective temperature value.

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