Power distribution systems in an electric aircraft

Abstract

An electric aircraft, in detail: a hull; one or more first electric propulsion units (EPUs) and one or more second EPUs arranged on one side of the fuselage, the one or more first EPUs being arranged in front of the one or more second EPUs; one or more third EPUs and one or more fourth EPUs arranged on another side of the fuselage, with the one or more third EPUs arranged in front of the one or more fourth EPUs; and a plurality of battery packs, wherein at least one of the plurality of battery packs is configured to supply energy to: a part of one of the first EPUs or more and a part of one of the fourth EPUs or more.

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

[0001] This application claims priority over the preliminary US patent application No. 17 / 115,119, filed on December 8, 2020, the entire contents of which are incorporated herein by reference. AREA

[0002] The field of the present invention relates generally to electric aircraft and in particular to the electrical power distribution for electric aircraft. BACKGROUND

[0003] Advances in battery technology have enabled battery energy densities suitable for powering lightweight electric aircraft. Electric propulsion systems for electric aircraft, especially passenger aircraft, must be safe, lightweight, and efficient. Safety considerations sometimes conflict with the goals of weight reduction and high efficiency. For example, conventional power distribution systems often employ multiple battery sets and redundancies within the system to ensure there is no single point of failure; however, this redundancy increases inefficiencies and adds weight. Reconciling safety, aircraft weight, and efficiency presents a challenge in electric aircraft design. SUMMARY

[0004] According to various embodiments, a power distribution system for an electric aircraft comprises a first battery pack connected to a load to supply power to the load, and a second battery pack via a common bus to share the load with the second battery pack. A first electrical disconnect device, such as a fuse, is electrically arranged between the first battery pack and the load, and a second electrical disconnect device is electrically arranged between the first battery pack and the common bus. The first electrical disconnect device acts faster than the second electrical disconnect device, for example, by having a shorter opening time at its rated current.In the event of an overcurrent fault in the electrical circuit between the first battery bank and the first load, the first disconnecting device interrupts the connection between the first battery bank and the load, while the second disconnecting device does not, for example, due to its slower-acting configuration. This protects the first battery from faults at the load or in the distribution between the battery and load, while allowing it to continue sharing its energy with the second battery bank. In the event of an overcurrent fault on the common bus, the second disconnecting device protects the first battery bank by disconnecting it from the common bus, enabling the first battery bank to continue supplying power to the load.By providing a common bus with the electrical isolation devices, the energy can be shared between the batteries, ensuring that the common bus does not represent a single point of failure.

[0005] According to various embodiments, a power distribution system for an electric aircraft comprises a first battery set connected to at least one first load and to a common bus connecting the first battery set in parallel with at least one second battery set; a first electrical component electrically connected between the first battery set and the first load and designed to disconnect the first load from the first battery set in response to a current above a first threshold current, wherein the first electrical component has a first disconnect time at the first threshold current; and a second electrical component electrically connected between the first battery set and the common bus and designed to disconnect the first battery set from the common bus in response to a current above a second threshold current.where the second electrical component has a second separation time at the second threshold current, which is higher than the first separation time.

[0006] In each of these embodiments, the first threshold current can be smaller than the second threshold current.

[0007] In each of these embodiments, the first battery set can be electrically connected to a second load, and a third electrical component can be electrically connected between the first battery set and the second load and have a third disconnect time at a third threshold current, wherein the third disconnect time can be lower than the second disconnect time.

[0008] In each of these embodiments, the third separation time can be the same as the first separation time.

[0009] In each of these embodiments, the second battery set can be connected to at least one second load, a third electrical component can be electrically connected between the second battery set and the second load and configured to disconnect the second load from the second battery set in response to a current above a third threshold current, wherein the third electrical component can have a third disconnect time at the third threshold current, and a fourth electrical component can be electrically connected between the first battery set and the common bus and configured to disconnect the second battery set from the common bus in response to a current above a fourth threshold current, wherein the fourth electrical component can have a fourth disconnect time at the fourth threshold current that is higher than the third disconnect time.

[0010] In each of these embodiments, at least one of the first and second electrical components can be a fuse.

[0011] In each of these embodiments, the safety device can be an explosive fuse, a thermal fuse, or a magnetic fuse.

[0012] In each of these embodiments, the common bus can connect the positive terminals of the first and second battery sets.

[0013] In each of these embodiments, the electrical circuits between the first battery set and the first load, as well as between the first battery set and the common bus, can be diode-free.

[0014] In each of these embodiments, the first load can be an electric drive unit. In each of these embodiments, the electric drive unit can include a propeller.

[0015] In each of these embodiments, the first battery set can contain a plurality of batteries arranged in series, in parallel, or in a combination of series and parallel.

[0016] In each of these embodiments, the first battery set can be designed to generate more than 100 volts.

[0017] In each of these embodiments, the electrical power of the first load can be at least 10 kilowatts.

[0018] In each of these embodiments, the system can include a third electrical component for selectively disconnecting the first battery pack from the first load or from the common bus. In each of these embodiments, the third electrical component can be electrically located between the first battery pack and the first electrical component or the second electrical component.

[0019] According to various embodiments, an electric aircraft can incorporate the aforementioned power distribution systems. In each of these embodiments, the aircraft can be manned. In each of these embodiments, the aircraft can be a vertical takeoff and landing (VTOL) aircraft.

[0020] According to various embodiments, a method for power distribution in an electric aircraft includes supplying power to a first load from a first battery set, wherein the first battery set is connected to a common bus which connects the first battery set in parallel to at least one second battery set, a first electrical component is electrically connected between the first battery set and the first load and is designed to disconnect the first load from the first battery set in response to a current above a first threshold, and a second electrical component is electrically connected between the first battery set and the common bus and is designed to disconnect the first battery set from the common bus in response to a current above a second threshold, wherein the second threshold is higher than the first threshold.

[0021] In each of these embodiments, the first threshold current can be smaller than the second threshold current.

[0022] In each of these embodiments, the first battery set can be electrically connected to a second load, and a third electrical component can be electrically connected between the first battery set and the second load and have a third disconnect time at a third threshold current, wherein the third disconnect time can be lower than the second disconnect time.

[0023] In each of these embodiments, the third separation time can be the same as the first separation time.

[0024] In each of these embodiments, the second battery set can be connected to at least one second load, a third electrical component can be electrically connected between the second battery set and the second load and configured to disconnect the second load from the second battery set in response to a current above a third threshold current, wherein the third electrical component can have a third disconnect time at the third threshold current, and a fourth electrical component can be electrically connected between the first battery set and the common bus and configured to disconnect the second battery set from the common bus in response to a current above a fourth threshold current, wherein the fourth electrical component can have a fourth disconnect time at the fourth threshold current that is higher than the third disconnect time.

[0025] In each of these embodiments, at least one of the first and second electrical components can be a fuse.

[0026] In each of these embodiments, the safety device can be an explosive fuse, a thermal fuse, or a magnetic fuse.

[0027] In each of these embodiments, the common bus can connect the positive terminals of the first and second battery sets.

[0028] In each of these embodiments, the electrical circuits between the first battery set and the first load, as well as between the first battery set and the common bus, can be diode-free.

[0029] In each of these embodiments, the first load can be an electric drive unit. In each of these embodiments, the electric drive unit can include a propeller.

[0030] In each of these embodiments, the first battery set can contain a plurality of batteries arranged in series, in parallel, or in a combination of series and parallel.

[0031] In each of these embodiments, the first battery set can be designed to generate more than 100 volts.

[0032] In each of these embodiments, the electrical power of the first load can be at least 10 kilowatts.

[0033] In each of these embodiments, the method may further include a third electrical component for selectively disconnecting the first battery pack from the first load or from the common bus. In each of these embodiments, the third electrical component may be electrically arranged between the first battery pack and the first electrical component or the second electrical component.

[0034] According to various embodiments, the method can be carried out by an electric aircraft. In each of these embodiments, the aircraft can be manned. In each of these embodiments, the aircraft can be a vertical take-off and landing (VTOL) aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present disclosure is now described only by way of example and with reference to the accompanying drawings, in which the following applies: Fig. Figure 1A shows a VTOL aircraft in a forward flight configuration according to various embodiments; Fig. Figure 1B shows a VTOL aircraft in a take-off and landing configuration according to various embodiments; The Fig. 2A and Fig. 2B illustrate a power distribution architecture for supplying the electric propulsion units of an aircraft, in which a large number of battery sets are detachably connected to a common bus, according to various embodiments; Fig. Figure 2C illustrates a power distribution architecture for supplying the electric propulsion units of an aircraft, in which two groups of battery sets are detachably connected to two common buses, according to various embodiments; Fig. Figure 3 is a block diagram of a circuit that connects two sets of batteries to each other and to a respective pair of electric drive units, according to various embodiments; Fig. Figure 4 is a block diagram of a circuit that connects two sets of batteries to each other and to a respective pair of electric drive units and includes optional contactors, according to various embodiments; The Fig. Figures 5-8 are block diagrams of various circuits that connect two battery sets to each other and to a respective pair of electric drive units, and include optional contactors and optional charging circuits, according to various embodiments; and Fig. Figure 9 is a block diagram of part of the power distribution for an electric drive unit containing two sub-motors, according to various embodiments. DETAILED DESCRIPTION

[0036] According to various embodiments, power distribution systems and methods in an electric aircraft involve supplying a multitude of aircraft loads with a multitude of battery sets, each connected to a different portion of the loads using different power distribution buses. For example, a first battery set is connected to a first portion of the loads using a first power distribution bus, and a second battery set is connected to a second portion of the loads using a second power distribution bus. At least some of the battery sets are electrically interconnected via a common bus, enabling load sharing between the connected battery sets. To protect a battery from an overcurrent fault event in the circuit from the battery to its connected load, a first electrical disconnect device, such as a battery isolator, is used.A fuse is electrically connected between the battery and the connected load. To protect a battery from an overcurrent fault event affecting the common bus, a second electrical disconnect device is electrically connected between the battery and the common bus. The first electrical disconnect device acts faster than the second, so an overcurrent event at the load does not disconnect the battery from the common bus, thus ensuring that the battery can still be connected to one or more additional batteries. Connecting the batteries allows for load sharing, which can offer the design advantage of smaller batteries and thus weight savings, while the combination of electrical disconnect devices ensures that there is no single point of failure.According to various embodiments, this can be achieved without diodes and / or without redundant buses, resulting in weight savings.

[0037] According to various embodiments, the multitude of loads includes electric propulsion units (EPUs). According to various embodiments, the EPUs include rotors designed to provide lift to the aircraft, such as during vertical takeoff and landing and hovering, which can be deactivated during cruise flight, as well as propellers that provide lift to the aircraft and can tilt forward to provide forward thrust for forward flight, with the lift being provided by one or more wings of the aircraft. According to various embodiments, each battery pack powers one EPU. According to various embodiments, each battery pack powers multiple EPUs.According to various embodiments, each battery pack supplies at least a portion of at least one rotor and at least a portion of at least one proprotor, such that if the battery pack or its power distribution bus is deactivated during forward flight, only the power to at least one portion of the at least one proprotor is lost. The other EPU(s) supplied by the lost battery pack, i.e., the rotor(s), do not contribute to forward power, so their loss does not affect forward flight. The remaining proprotor portions (supplied by other battery packs) can continue to operate, with adjustments to the control surfaces and / or the power output of the remaining proprotor portions compensating for the lost proprotor portions.Thus, the impact of losing a battery pack on forward flight can be minimized, while simultaneously ensuring fault tolerance without the increased weight associated with diodes and / or redundant power distribution buses. According to various embodiments, each battery pack powers the equivalent of one proprotor (in addition to a certain proportion of the rotors), so that the forward power loss due to the loss of a battery pack is only the equivalent of one proprotor's power.

[0038] In various embodiments, a single common bus connects all battery sets that power the EPUs. In various embodiments, a first group of battery sets is connected via a first common bus, and a second group of battery sets is connected via a second common bus. In various embodiments, the first group of battery sets differs from the second group of battery sets in type and / or number. In various embodiments, the first group of battery sets powers the rotors, and the second group of battery sets powers the proprotors.

[0039] According to various embodiments, the aircraft is an electric, vertical take-off and landing (VTOL or eVTOL) aircraft capable of vertical take-off and landing as well as hovering, thus offering the possibility of bringing passengers closer to their destination than would be possible with aircraft requiring a runway. According to various embodiments, the aircraft is an eVTOL fixed-wing aircraft.

[0040] In various embodiments, the EPUs powered by a particular battery pack are selected to reduce destabilizing effects caused by a loss of power to the EPUs in the event of a battery pack failure. EPUs located on opposite sides of one or more axes of symmetry of the EPU array can be powered by the same battery pack to reduce roll, pitch, or yaw moments that may result from a loss of power to the EPUs powered by that battery pack. For example, EPUs located on both sides of the aircraft's longitudinal axis in the same relative position can be powered by a first battery pack, such that if one of the battery packs fails, only minimal roll moments will occur, since the thrust provided by the remaining EPUs will still be uniform around the longitudinal axis.Similarly, in some embodiments the EPUs are arranged forward and rearward of a group of wings, and EPUs on opposite sides of the wings and on opposite sides of the longitudinal axis can be powered by the same battery pack.

[0041] According to various embodiments, the portion of the EPU powered by a battery pack can contain part of a single EPU motor, such that part of an EPU motor is powered by a first battery pack and another part of the EPU motor is powered by a second battery pack. For example, an EPU can contain two half-motors that can operate together under normal conditions to drive multiple blades that provide thrust to the aircraft, with one half-motor being powered by one battery pack and the other half-motor being powered by a different battery pack. In the event of a failure of one of the battery packs, the EPU remains operational at half power. A single battery pack can power partial motors of different EPUs, so that the impact of the loss of one battery pack is distributed among several EPUs that continue to operate at reduced power.

[0042] The following description of the disclosure and embodiments refers to the accompanying drawings, which illustrate specific embodiments that can be implemented in practice. It is understood that other embodiments and examples can also be implemented in practice and modifications can be made without deviating from the scope of the disclosure.

[0043] Additionally, the singular forms "ein," "eine," and "der," "die," "das" used herein also include the plural forms, unless the context clearly indicates otherwise. It is also understood that the term "and / or," as used herein, refers to and includes all possible combinations of one or more of the related listed elements. Furthermore, it is understood that the terms "contains," "containing," "comprises," and / or "comprehensive," when used herein, specify the presence of certain features, integers, steps, operations, elements, components, and / or units, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, units, and / or groups thereof.

[0044] As used herein, the term "proporator" refers to a variable-pitch propeller which can provide thrust for vertical lift and forward propulsion by varying the angle of attack of the propeller.

[0045] As used herein, the term 'battery set' means any combination of electrically connected batteries (i.e., battery cells) and may include a variety of batteries arranged in series, parallel, or in a combination of series and parallel.

[0046] The Fig. 1A and Fig. Figure 1B illustrates a VTOL aircraft 100 in a travel configuration and a vertical take-off and landing configuration according to various embodiments. Exemplary embodiments of a VTOL aircraft according to various embodiments are discussed in U.S. Patent Application No. 16 / 878,380 entitled “Vertical Take-Off and Landing Aircraft”, which was filed on May 19, 2020, the entire contents of which are incorporated herein by reference.

[0047] The aircraft 100 comprises a fuselage 102, wings 104 attached to the fuselage 102, and one or more tail stabilizers 106 attached to the rear of the fuselage 102. The aircraft 100 comprises a plurality of rotors 112 and a plurality of proprotors 114 (hereinafter collectively referred to as EPUs). The EPUs (112, 114) generally comprise an electric motor that drives a fan (a plurality of blades) and a motor controller for controlling / supplying the motor. As further described below with regard to Fig. As discussed in section 4, an EPU can contain a variety of sub-motors that can drive the fan independently and collectively, and can be controlled by a variety of separate motor controllers.

[0048] The rotors 112 are mounted on the wings 104 and are designed to provide lift for vertical takeoff and landing. The proprotors 114 are mounted on the wings 104 and are intermediate in lift configurations, in which they provide a portion of the lift required for vertical takeoff and landing as well as for hovering, as shown in Fig. 1B shown, and propulsion configurations in which they provide the aircraft with 100 forward thrust for level flight, as in Fig. 1A shown, tiltable. As used herein, a propeller lift configuration refers to any propeller orientation in which the propeller thrust primarily provides lift for the aircraft, and a propeller drive configuration refers to any propeller orientation in which the propeller thrust primarily provides forward thrust for the aircraft.

[0049] According to various embodiments, the rotors 112 are designed exclusively for providing lift, with all propulsion being provided by the proprotors. Accordingly, the rotors 112 can be in fixed positions. During takeoff and landing, the proprotors 114 are tilted into lift configurations in which their thrust is directed downwards to provide additional lift.

[0050] For forward flight, the proprotors 114 tilt from their lift configurations to their thrust configurations. In other words, the angle of attack of the proprotors 114 is varied from an angle where the proprotor thrust is directed downwards to provide lift during vertical takeoff and landing, as well as hovering, to an angle of attack where the proprotor thrust is directed backwards to provide forward thrust to the aircraft 100. The proprotors tilt about the axes 118, which are perpendicular to the forward direction of the aircraft 100. When the aircraft 100 is in pure forward flight, lift can be provided entirely by the wings 104, and the rotors 112 can be shut down. The blades 120 of the rotors 112 can be locked in low-drag positions for cruise flight.In some embodiments, the rotors 112 each have two blades 120 which are locked in positions with minimal air resistance for cruise flight, in which one blade is located directly in front of the other blade, as in . Fig. Figure 1A illustrates this. In some embodiments, the rotors 112 have more than two blades. In some embodiments, the proprotors 114 contain more blades 116 than the rotors 112. For example, the rotors 112, as shown in Fig. 1A and Fig. Figure 1B illustrates that each proprotors 114 contains two leaves, and each proprotors 114 can contain five leaves. According to various embodiments, the proprotors 114 can have between two and five leaves.

[0051] According to various embodiments, the aircraft includes only one wing 104 on each side of the fuselage 102 (or a single wing extending over the entire aircraft), and at least part of the rotors 112 are located aft of the wings 104 and at least part of the proprotors 114 are located forward of the wings 104. In some embodiments, all rotors 112 are located aft of the wings 104 and all proprotors are located forward of the wings 104. According to some embodiments, all rotors 112 and proprotors 114 are attached to the wings, i.e., no rotors or proprotors are attached to the fuselage. According to various embodiments, the rotors 112 are all located behind the wings 104, and the proprotors 114 are all located in front of the wings 104. According to some embodiments, all rotors 112 and proprotors 114 are arranged within the wing tips 109.

[0052] According to various embodiments, the rotors 112 and the proprotors 114 are attached to the wings 104 by means of booms 122. The booms 122 can be located below or on top of the wings 104 and / or integrated into the wing profile. In various embodiments, one rotor 112 and one proprotor 114 are attached to each boom 122. The rotor 112 can be attached to a rear end of the boom 122, and a proprotor 114 can be attached to a front end of the boom 122. In some embodiments, the rotor 112 is fixed in position on the boom 122. In some embodiments, the proprotor 114 is attached to a front end of the boom 122 via a hinge 124.The proprotor 114 can be attached to the boom 122 in such a way that the proprotor 114 is aligned with the body of the boom 122 when it is in its propulsion configuration, forming a continuous extension of the front end of the boom 122, which minimizes drag for forward flight.

[0053] According to various embodiments, the aircraft 100 may have only one wing on each side or a single wing extending over the entire aircraft. According to some embodiments, the at least one wing 104 is a high-wing monoplane attached to the upper surface of the fuselage 102. According to some embodiments, the wings include control surfaces, such as flaps and / or ailerons. According to some embodiments, the wings may have curved wingtips 109 to reduce drag during forward flight.

[0054] According to some embodiments, the tail stabilizers 106 include control surfaces, such as one or more rudders, one or more elevators, and / or one or more combined rudders and elevators. The wing(s) may have any suitable shape. In some embodiments, the wings have a tapered leading edge 123, as for example in the embodiment of Fig. 1A shown. In some embodiments, the wings have a tapered trailing edge.

[0055] Fig. Figure 2A illustrates a power distribution architecture for supplying the EPUs (112, 114) of aircraft 100 according to various embodiments. Although the Fig. 1A-2A 12 EPUs illustrate (numbered 1-12 in Fig. 2A), which are attached to the wings 104, the aircraft can, according to various embodiments, have any number of EPUs, including four, six, eight, ten, fourteen, eighteen, twenty or more. The EPUs are powered by a plurality of battery sets 200. In the Fig. In the illustrated embodiment 2A, there are six battery sets 200 numbered 1 to 6. Each battery set 200 powers only a portion of the EPUs. In the illustrated embodiment, each battery set 200 powers two EPUs. The grouping of battery sets and EPUs according to the Fig. The embodiment illustrated in 2A is in Fig. Listed in 2B. Battery set 1 supplies EPUs 1 and 12, battery set 2 supplies EPUs 2 and 11, and so on. Each battery set 200 is connected to its respective portion of the EPUs via a dedicated power distribution bus, e.g., bus 202, which connects battery set 1 to EPU 1 and EPU 12, and bus 204, which connects battery set 2 to EPU 2 and EPU 11. Therefore, the power distribution bus 202 of battery set 1 is not electrically connected to the power distribution bus 204 of battery set 2.

[0056] According to various embodiments, the battery sets 200 are interconnected via a common bus 206, to which each battery set 200 is detachably connected. The battery sets can be loaded together via the common bus 206, thereby reducing the maximum power required of a particular battery set. The lower maximum power requirement can mean smaller batteries, enabling weight savings and / or batteries using cells with lower power and higher energy, thus increasing the range. As described below, an electrical disconnect device, such as a bus, is connected between each battery set and the common bus.A fuse is provided so that, in the event of an overcurrent fault affecting the common bus, the battery sets are protected by being disconnected from the common bus by the electrical isolating device, while the EPUs to which they are directly connected can continue to be powered. Furthermore, according to some embodiments, an electrical failure in one battery set or its power distribution unit does not cause the other EPUs and battery sets to fail. Only the EPUs powered by the failed battery or power distribution unit are affected. Thus, there is no single point of failure in the aircraft's power supply.

[0057] According to various embodiments, the individual EPUs powered by a particular battery pack can be selected to reduce destabilization effects caused by a loss of power to the EPUs in the event of a battery pack failure. According to various embodiments, EPUs located on opposite sides of one or more axes of symmetry of the array of EPUs can be powered by the same battery pack to reduce roll, pitch, or yaw moments that may be caused by a loss of power to the EPUs powered by that battery pack.For example, EPUs located on both sides of the longitudinal axis 280 of the aircraft 100 in the same relative position can be powered by a first battery set, such that if one of the battery sets fails, only minimal roll moments occur, since the thrust provided by the remaining EPUs is maintained uniformly around the longitudinal axis. Similarly, in some embodiments, a group of EPUs is arranged at least partially forward of the leading edge of a pair of wings and a group of EPUs is arranged at least partially aft of the trailing edge of the pair of wings, and EPUs on opposite sides of the wings and on opposite sides of the longitudinal axis 280 can be powered by the same battery set, so that minimal roll and pitch moments occur in the event of the battery set failure (as in ). Fig. 2A shown).

[0058] According to various embodiments, each battery set 200 supplies at least a portion of the at least one proprotor 114 and at least a portion of the at least one rotor 112. In the embodiment of Fig. In 2A, rotors and proprotors at opposite positions are driven by the same battery pack 200. Thus, the outermost proprotor 114 on the left side of the fuselage 102 of the aircraft (EPU 1 in Fig. 2A) from the same battery set (battery set 1 in Fig. 2A) like the outermost rotor 112 on the right side of the fuselage 102 (EPU 12). Similarly, the other pair of outermost EPUs (EPU 6 and EPU 7 in Fig. 2A) is powered by the same battery pack (battery pack 6). The groupings do not have to be limited to EPUs in exactly opposite positions. For example, EPU 1 can be grouped with EPU 11 instead of EPU 12.

[0059] The number of EPUs powered by a given battery set can be greater than two. For example, in some embodiments, the number of EPUs per battery set can be three, four, five, six, or another suitable proportion of the total number of EPUs. According to various embodiments, there can be a different number of EPUs within each group. For example, one group can have two EPUs (two EPUs powered by one battery set), while another group can have four EPUs (four EPUs powered by a different battery set). The number of battery sets can be up to two. In various embodiments, the number of battery sets is at least three, at least four, at least five, at least six, at least seven, at least eight, or more.

[0060] Fig. Figure 2C illustrates an embodiment in which the battery sets are arranged in isolated groups. A first group 230 of battery sets (battery sets 1-6 in the illustrated embodiment) is connected to each other via a first common bus 232, and a second group 234 of battery sets (battery sets 7-12 in the illustrated embodiment) is connected to each other via a second common bus 236. The first and second common buses 232 and 236 are electrically isolated from each other, so that there is no electrical connection between the first group 230 of battery sets and the second group 234 of battery sets.

[0061] According to various embodiments, each battery set of the first group 230 supplies one proprotor 114 and each battery set of the second group 234 supplies one rotor 112. According to some embodiments, the power requirements (e.g. peak power and / or power during a flight) of the proprotors 114 and the rotors 112 may differ, and the battery sets of the first and second groups may have different types and / or sizes based on the different power requirements of the proprotors 114 and the rotors 112.For example, in some embodiments the proprotors 114 can be used in vertical and horizontal flight, while the rotors 112 can only be used in vertical flight, and therefore the total power required by the proprotors 114 during a flight may be greater than the total power required by the rotors 112 during the flight, and to compensate for this difference, the battery sets of the first group 230 may be larger than the battery sets of the second group 234.

[0062] Fig. Figure 3 is a block diagram of at least one part of a power distribution system 300 of an electric aircraft. Two battery sets 300 and 350 are shown, each battery set designed to be connected to two loads. However, it is understood that the illustrated embodiment is merely exemplary and any number of battery sets can be used and connected to any number of loads, such as any number of EPUs and / or any number of parts of EPUs, as discussed above. In the illustrated embodiment, battery set 300 is electrically connected to a pair of EPUs 302, 304. EPU 302 can, for example, power EPU 1 of Fig. 2A, and EPU 304 can, for example, be EPU 12 from Fig. The battery pack 300 is connected to the EPUs 302 and 304 via a power distribution bus 306. A first electrical load disconnect device 308 can be electrically arranged between the first battery pack 300 and the EPU 302 to disconnect the first battery pack 300 from the EPU 302 in the event of an overcurrent fault event (e.g., a ground fault) associated with the EPU 302 or a part of the power distribution bus 306 downstream of the electrical disconnect device 308. A second electrical load disconnect device 310 can be electrically arranged between the first battery set 300 and the EPU 304 to disconnect the first battery set 300 from the EPU 304 in the event of an overcurrent fault event related to the EPU 304 or a part of the power distribution bus 306 downstream of the electrical disconnect device 310.

[0063] The first battery pack 300 is electrically connected to a common bus 314, to which the second battery pack 350 is also electrically connected. The current can be shared between the first and second battery packs 300 and 350 (and all other battery packs connected to the common bus 314) via the common bus 314. This allows, for example, the power supply for EPU 302 and / or EPU 304 to be drawn from both the first and second battery packs 300 and 350.

[0064] A first electrical disconnect device for the common bus 312 is electrically arranged between the first battery pack 300 and the common bus 314 to disconnect the first battery pack 300 from the common bus 314 in the event of an overcurrent fault. This can protect the first battery pack 300 from an overcurrent fault associated with the common bus 314, which could be, for example, a ground fault affecting the common bus 314 or a fault affecting the battery pack connected to the common bus 314. The first disconnect device for the common bus 312 can also protect the common bus 314 from an overcurrent fault affecting the battery pack 300 itself.

[0065] According to various embodiments, the first electrical disconnect device for the common bus 312 is slower than the first and second electrical load disconnect devices 308 and 310. For example, in some embodiments, the electrical disconnect device for the common bus 312 may have a slower disconnect time (also referred to in technical language as opening time or clearing time) at its rated current threshold than the first and second electrical load disconnect devices 308 and 310.Should an overcurrent fault occur on the power distribution bus 306, the EPU 302, and / or the EPU 304 due to the different disconnection times, causing a current spike at the first and / or second disconnect device 308, 310 exceeding their rated currents, and a current spike at the electrical disconnect device for the common bus 312 exceeding its rated current, the first and / or second electrical disconnect device 308 and 310 protect the battery pack 300 while the battery pack 300 remains connected to the common bus 314, since the first electrical disconnect device for the common bus 312 does not disconnect because it reacts more slowly than the first and / or second electrical disconnect device 308 and 310. In some embodiments, one or both of the load disconnect devices 308, 310 have a lower disconnect current threshold than the disconnect device for the common bus 312.For example, one or more load disconnect devices may have a disconnect threshold of 300 amperes and a disconnect time of 140 ms at their disconnect threshold current, and the common bus fuse may have a disconnect threshold of 500 amperes and a disconnect time of 360 ms at its disconnect threshold current. In some embodiments, a load disconnect device has the same disconnect threshold as the common bus disconnect device 312. For example, the load disconnect device and the common bus disconnect device may have a disconnect threshold of 500 amperes, with the load disconnect device having a disconnect time of 140 ms at the threshold current and the common bus disconnect device having a disconnect time of 300 ms at the threshold current.

[0066] According to various embodiments, the second battery pack 350 can be connected to the EPUs 352 and 354 via the power distribution bus 356. The third and fourth electrical load disconnect devices 358 and 360 can be electrically arranged between the second battery pack 350 and the EPUs 352 and 354 to disconnect the second battery pack from the EPUs during an overcurrent fault event, as discussed above with respect to the first battery pack 300 and the EPUs 302 and 304. The second electrical disconnect device for the common bus 362 can be electrically arranged between the second battery pack 350 and the common bus 314.The second electrical disconnect device for the common bus 362 may be slower than either of the third and fourth electrical load disconnect devices 358 and 360, as discussed above with respect to the first electrical disconnect device for the common bus 312 and the first and second electrical load disconnect devices 308 and 310.

[0067] According to various embodiments, the electrical disconnect devices for the common bus 312 and 362, which can disconnect the respective battery sets from the common bus 314, have the same disconnect current thresholds and / or the same disconnect times at their disconnect current threshold. In some embodiments, the first electrical disconnect device for the common bus 312 has a different disconnect threshold and / or a different opening time than the second electrical disconnect device for the common bus 362. In some embodiments, the disconnect current thresholds and / or the opening times of the electrical load disconnect devices 308 and 310 differ from each other, e.g., due to different load requirements of the EPUs 302 and 304.In some embodiments, the threshold values ​​for the disconnecting current and / or the opening times of one or both electrical load disconnect devices 308 and 310 are the same as the threshold values ​​for the disconnecting current and / or the opening times of one or both electrical load disconnect devices 358 and 360.

[0068] Each of the electrical disconnecting devices 308, 310, 312, 358, 360, and 362 can be any suitable electrical component for interrupting the circuit in the event of an overcurrent fault. For example, one or more of the electrical disconnecting devices is a fuse, a circuit breaker, or a switch operatively coupled to a current detector. According to some embodiments, each of the electrical disconnecting devices 308, 310, 312, 358, 360 is a fuse. According to some embodiments, the electrical disconnecting devices can be any suitable type of fuse or a combination of fuse types. For example, one or more of the electrical disconnecting devices 308, 310, 312, 358, 360 is an explosive fuse, a thermal fuse, or a magnetic fuse.According to some embodiments, the electrical disconnect devices for the common bus are a first type of electrical disconnect device, and the electrical load disconnect devices are a second type of electrical disconnect device that differs from the first type. For example, the electrical load disconnect devices 308 and 310 may be explosive fuses, and the electrical disconnect device for the common bus 312 may be thermal fuses.

[0069] According to various embodiments, the threshold value for the disconnecting current of one or more of the electrical load disconnect devices 308, 310, 358 and 360 is at least 50 amperes, at least 100 amperes, at least 200 amperes, at least 300 amperes or at least 500 amperes. According to various embodiments, the threshold value for the disconnecting current of one or more of the electrical disconnecting devices for the common bus 312, 362 is at least 100 amperes, at least 200 amperes, at least 300 amperes, at least 400 amperes, at least 500 amperes, at least 600 amperes or at least 1000 amperes.According to some embodiments, the threshold current for the disconnecting current of one or more electrical disconnect devices for the common bus is at least 10% higher, at least 20% higher, at least 30% higher, at least 50% higher, at least 66% higher, at least 75% higher, or at least 100% higher than the threshold current of one or more electrical load disconnect devices. According to various embodiments, the opening time of one or more electrical load disconnect devices and / or disconnect devices for the common bus at their rated current threshold is 1 second or less, 500 ms or less, 400 ms or less, 300 ms or less, 200 ms or less, 100 ms or less, 50 ms or less, or 10 ms or less.According to various embodiments, the opening time of one or more load disconnect devices at their nominal threshold current can be at least 100 times faster, at least 50 times faster, at least 10 times faster, at least 5 times faster or at least 2 times faster compared to the opening time of the disconnect devices for the common bus at their nominal threshold current.

[0070] According to some embodiments, the negative terminals 320, 370 of the battery sets 300, 350 are electrically connected to a common negative bus 316. According to some embodiments, the common bus 314 is electrically connected to the positive terminals 318, 368 of the battery sets 300, 350. According to various embodiments, the power distribution system 300 is free of diodes that control the charge flow between the batteries 300, 350. According to various embodiments, this can make the power distribution system 300 more efficient compared to a system containing diodes, which can lead to weight savings.

[0071] According to various embodiments, the power distribution system 300 includes one or more contactors for selectively electrically isolating one or more parts of the power distribution system 300, such as during battery charging and / or to put the power distribution system into a safety mode after the aircraft has been shut down. Fig. Figures 4-8 illustrate various guard arrangements according to different embodiments. Fig. A contactor 402 is electrically arranged between the first battery set 300 and the first and second electrical load disconnect devices 308 and 310. A contactor 404 can optionally be electrically arranged between the first battery set 300 and the first electrical disconnect device for the common bus 312. A contactor 406 can optionally be electrically arranged between the first battery set 300 and the common negative bus 316. A similar contact arrangement can be used for the second battery set 350 and is not described separately for the sake of brevity (the same applies to the variants described below).

[0072] In Fig. A contactor 502 is electrically arranged between the first electrical load break device 308 and the EPU 302, a second contactor 504 is electrically arranged between the second electrical load break device 310 and the EPU 304. A third contactor 506 can optionally be electrically arranged between the first battery set 300 and the common negative bus 316. Fig. Figure 5 illustrates a charging circuit 550 for charging battery sets 300 and 350 according to various embodiments. A charging port 552 can be used to connect an external charger to the power distribution network. The charging port 552 can be connected to the common bus 314 and the common negative bus 316. A charging contactor 554 and a charging fuse 556 can be arranged between the charging port 552 and the common bus 314. The embodiment of Fig. 6 is similar to the one from Fig. 5 with the difference that instead of the charging contactor 554, the contactor 602 is provided between the electrical isolating device for the common bus 312 and the battery set 300.

[0073] Fig. Figure 7 illustrates a configuration with a minimal number of contactors for the arrangement of battery sets, loads, and charging circuitry. A contactor 702 is located at the positive terminal 318 of battery set 300 to disconnect battery set 300 from both the EPUs 302 and 304, as well as from the common bus 314. An optional contactor 704 can be installed at the negative terminal 320 of battery set 300. The in Fig. Variant 8, illustrated, is similar to that of Fig. 7, with the difference that the charging circuit 850 is directly connected to the battery pack 300 and not to the common bus 314. The charging port 852 can be connected to a charging bus 860. The battery pack 300 can be connected to the charging bus 860, with a charging fuse 854 and a charging contactor 856 being electrically arranged between the battery pack 300 and the charging bus 860.

[0074] In some embodiments, the EPUs, or at least some of the EPUs, contain multiple motor stages, each of which is independently powered by different battery sets, so that if one battery set fails, only part of the EPUs is not powered and the EPU can continue to operate with reduced power. Fig. Figure 9 is a block diagram of part of the power distribution for an EPU 900, which contains two sub-motors – 902A and 902B. The EPU 900 can be a rotor, such as rotor 112 from Fig. 1A, or a proprotor, such as the Proprotor 114 from Fig. 1A. The two sub-motors 902A and 902B can be operated independently to drive the fan blades 904 via the shaft 906, and can be operated simultaneously to drive the fan blades 904 at a higher power. The sub-motors 902A and 902B are driven by their own motor controllers 908A and 908B, respectively. The sub-motor 902A and the motor controller 908A are powered by the battery pack 950 via the power distribution bus 960, while the sub-motor 902B and the motor controller 908B are powered by the battery pack 952 via the power distribution bus 962.Battery sets 950 and 952 are electrically connected to each other via the common bus 910, which can be disconnected from each of the battery sets 950 and 952 via electrical isolating devices for the common bus 912 and 916 according to the principles discussed above. Thus, in the event of an overcurrent fault on the common bus 910, the sub-motor 902A, the motor control 908A, the distribution bus 960, and the battery set 950 are electrically isolated from the sub-motor 902B, the motor control 908B, the distribution bus 962, and the battery set 952. Therefore, an electrical failure affecting the common bus 910 and / or the first sub-motor 902A does not affect the second sub-motor 902B, and vice versa. Thus, the EPU 900 can continue to operate, albeit with reduced power, in the event that the common bus 910 and / or one of the battery sets 950 or 952 should fail.Furthermore, the electrical load disconnect devices 914, 918, in accordance with the principles discussed above, protect the corresponding battery sets 950, 952 from overcurrent faults in the associated sub-motors, motor controls and power distribution buses.

[0075] According to various embodiments, a battery pack can power partial motors of opposing EPUs. For example, consider... Fig. 2A, the first battery set 1 can power a first sub-motor of EPU 1, a first sub-motor of EPU 12, a first sub-motor of EPU 6, and a first sub-motor of EPU 7. Thus, in the event of a failure of battery set 1, both the rotors and the propellers at the same relative position on opposite sides of the aircraft will lose at least half of their maximum available power, but will remain operational.

[0076] The battery packs for powering the EPUs can be located at any suitable location on the aircraft, including the fuselage and / or wings. The number and power of the EPUs can be selected according to the desired performance parameters (e.g., target payload, airspeed, and altitude). According to various embodiments, the maximum rated power of one or more EPUs is 500 kilowatts or less, preferably 200 kilowatts or less, and more preferably 150 kilowatts or less. According to some embodiments, the maximum rated power of one or more EPUs is at least 10 kilowatts, preferably at least 20 kilowatts, and more preferably at least 50 kilowatts. The aircraft can have an equal number of rotors and propellers, a greater number of propellers, or a greater number of rotors.

[0077] According to various embodiments, each battery pack is designed for a maximum stored energy of at least 1 kilowatt-hour, or preferably at least 10 kilowatt-hours, and / or a maximum stored energy of at most 200 kilowatt-hours, preferably at most 100 kilowatt-hours, more preferably at most 75 kilowatt-hours, and even more preferably at most 50 kilowatt-hours. According to various embodiments, the battery packs are designed such that their collective maximum stored energy is at least 1 kilowatt-hour, or preferably at least 10 kilowatt-hours, and / or their maximum stored energy is at most 200 kilowatt-hours, preferably at most 100 kilowatt-hours, more preferably at most 75 kilowatt-hours, or even more preferably at most 50 kilowatt-hours.According to various embodiments, at least some of the battery sets provide a voltage of at least 100 volts, at least 500 volts, or at least 1000 volts when fully charged. According to various embodiments, at least some of the battery sets provide a maximum of 2000 volts, at most 1500 volts, at most 1000 volts, or at most 500 volts when fully charged. According to some embodiments, the maximum nominal voltage is between 500 and 1000 volts, preferably between 600 and 800 volts, or even more preferably between 650 and 750 volts.

[0078] According to various embodiments, the EPUs are sized to compensate for the loss of some EPUs due to the failure of a battery pack, in accordance with the principles discussed above. For example, if two EPUs are lost due to the failure of the battery pack powering them, the remaining EPUs and their associated battery packs can be sufficiently sized to provide additional thrust to at least partially compensate for the thrust loss of the deactivated EPUs.

[0079] Aircraft based on the principles discussed above can be designed to carry at least one person and up to ten people, preferably up to six people, and more preferably up to four people. According to some embodiments, the aircraft is designed to be controlled and includes controls. In some embodiments, the aircraft is designed to operate autonomously without a pilot on board and with or without one or more passengers.

[0080] According to some embodiments, the aircraft is designed to carry up to six people (for example, a pilot and up to five passengers) up to 75 miles at a cruising speed of up to 150 miles per hour at an altitude of up to 3,000 feet above ground level. In some embodiments, the aircraft is designed for five people, for example, a pilot and four passengers. According to various embodiments, the maximum range on a single battery charge is 25 miles, 50 miles, 75 miles, 100 miles, or 200 miles.

[0081] According to various embodiments, the rotors 112 and / or the proprotors 114 are designed to have a relatively low peak speed in order to reduce the amount of noise generated by the aircraft. In some embodiments, the peak speed of the rotor blades in hovering flight is approximately Mach 0.4. According to various embodiments, the diameter of the rotor and / or proprotor blades is in the range of 1 to 5 meters, preferably in the range of 1.5 to 2 meters.

[0082] According to various embodiments, the wingspan is in the range of 10 to 20 meters, preferably in the range of 15 to 16 meters. According to various embodiments, the length of the aircraft is in the range of 3 to 20 meters, preferably in the range of 5 to 15 meters, and even more preferably in the range of 6 to 10 meters.

[0083] According to various embodiments, the aircraft is operated during takeoff and landing by arranging the proprotors in lift configurations, thus providing the aircraft with the required lift via the combined lift generated by the rotors and proprotors. According to various embodiments, the proprotors can be maintained in predetermined lift configurations during vertical takeoff and landing and / or hovering, which may be the same for all proprotors or different for different proprotors. According to various embodiments, the tilt of at least some proprotors can be actively adjusted during takeoff and landing and / or hovering to ensure the required stability and / or maneuverability.According to some embodiments, the tilt of at least one proprotor during takeoff and landing and / or hovering is actively controlled by the flight control system to generate yaw moments.

[0084] According to various embodiments, each rotor and / or proprotor can be individually controlled by the flight control system according to its various operational degrees of freedom. In some embodiments, the rotor's only degree of freedom is its rotational speed. In others, the pitch angle of the rotor blades can be collectively adjusted, providing an additional degree of freedom. In other embodiments, the degrees of freedom of at least some of the proprotors include the proprotor rotational speed, the collective pitch angle of the blades, and the proprotor tilt angle. In other embodiments, each of these degrees of freedom can be actively controlled by the flight control system during takeoff and landing (either autonomously or in response to pilot commands) to ensure appropriate stability and maneuverability.

[0085] Once the aircraft has reached a sufficient altitude to begin forward flight, the proprotors begin to tilt forward toward their propulsion configurations, so that their thrust provides a combination of lift and thrust, with the lift component decreasing as the proprotors tilt further toward their propulsion configurations. The rotors may remain active, at least for part of the time the proprotors are tilted forward, to continue providing rotor-assisted lift. Once the forward airspeed is high enough for the wings to provide sufficient lift to maintain the aircraft's altitude, the rotors may be deactivated at any time. As discussed above, the rotor blades may be locked in a low-drag position.

[0086] During cruise flight, the rotors remain deactivated. The wing control surfaces and / or tail stabilizers can be used in the conventional manner to improve the aircraft's maneuverability and stability. According to some embodiments, in the event of a battery pack being lost during forward flight, resulting in the loss of power to the propellers powered by that pack, the aircraft can compensate for this loss by using the control surfaces and / or by adjusting the power output of the unaffected portion of the propellers.

[0087] According to some embodiments, the pitch of at least some proprotors can be actively controlled to provide additional stability and / or maneuverability. In some embodiments, the pitch of at least some of the proprotors is actively controlled during takeoff and landing and / or hovering. In some embodiments, the pitch of the proprotors is fixed (i.e., not variable) during cruise flight. According to some embodiments, the pitch of the outermost proprotors can be actively and independently controlled during vertical takeoff and landing and / or hovering to provide yaw moments when required.

[0088] According to various embodiments, the EPUs (rotors and propellers) can be supplied according to the power distribution architecture described herein. For example, one method for supplying an aircraft involves supplying, by means of a first battery set, a first plurality of electric drive units, which are attached to at least one wing of the aircraft and are arranged at least partially forward of a leading edge of the at least one wing, via a first electrical power bus that electrically connects the first battery set to at least part of the first electric drive unit of the first plurality of electric drive units and to at least part of the first electric drive unit of the second plurality of electric drive units.The method also includes supplying, by means of a second battery set, a second plurality of electric drive units, which are attached to the at least one wing and arranged at least partially rearward of a trailing edge of the at least one wing, via a second electric current bus, which electrically connects the second battery set to the at least part of the second electric drive unit of the first plurality of electric drive units and to the at least part of the second electric drive unit of the second plurality of electric drive units, wherein the second electric current bus is electrically isolated from the first electric current bus.

[0089] According to various embodiments, a method for powering an aircraft includes supplying, via a first battery pack, at least a portion of a first rotor and at least a portion of a first proprotor through a first electrical power bus that electrically connects the first battery pack to the at least portion of the first rotor and the at least portion of the first proprotor. The method also includes supplying, via a second battery pack, at least a portion of a second rotor and at least a portion of a second proprotor through a second electrical power bus that electrically connects the second battery pack to the at least portion of the second rotor and the at least portion of the second proprotor, wherein the second electrical power bus is electrically isolated from the first electrical power bus.

[0090] According to various embodiments, if a battery pack or the power distribution to that battery pack should fail during flight, such as during vertical takeoff or landing, hovering, or forward flight, only the EPUs powered by that battery pack are deactivated. The remaining EPUs, powered by other battery packs that are electrically isolated from the deactivated battery pack, continue to operate. According to various embodiments, the power output of at least some of the unaffected EPUs can be increased to compensate for the thrust loss of the deactivated EPUs.

[0091] In various embodiments, the battery sets supply different motor sections of the same EPU, so that in the event of the loss of one of the battery sets or its power distribution, the affected EPUs can continue to operate at reduced power. In various embodiments, the power of the unaffected motor section can be increased and / or the power of the unaffected EPUs can be increased to compensate for the loss of thrust from the deactivated motor sections.

[0092] The foregoing description has been provided for illustrative purposes with reference to specific embodiments. However, the above illustrative discussions do not claim to be exhaustive, nor do they limit the invention to the exact forms disclosed. Many modifications and variations are possible with regard to the teachings above. The embodiments have been selected and described to best explain the principles of the techniques and their practical applications. This enables other skilled persons to make optimal use of the techniques and the various embodiments with different modifications suitable for their respective intended uses.

[0093] Although the disclosure and the examples have been fully described with reference to the accompanying figures, it should be noted that various changes and modifications will be apparent to the person skilled in the art. Such changes and modifications are to be understood as falling within the scope of the disclosure and the examples defined in the claims. Finally, the entire disclosure of the patents and publications referenced in this application is hereby incorporated by reference. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 17 / 115,119

[0001] US 16 / 878,380

[0046] Cited non-patent literature

[0000] Vertical Take-Off and Landing Aircraft” discussed on May 19, 2020

[0046]

Claims

[1] An electric aircraft comprising: a hull; one or more first electric propulsion units (EPUs) and one or more second EPUs arranged on one side of the fuselage, the one or more first EPUs being arranged in front of the one or more second EPUs; one or more third EPUs and one or more fourth EPUs arranged on another side of the fuselage, with the one or more third EPUs arranged in front of the one or more fourth EPUs; and a plurality of battery packs, wherein at least one of the plurality of battery packs is configured to supply energy to: a part of one of the first EPUs or more and a part of one of the fourth EPUs or more. [2] The electric aircraft according to claim 1, wherein: one of the first EPUs and one of the fourth EPUs are located furthest from the fuselage among the first EPUs and the fourth EPUs; or another of the plurality of battery packs is arranged to power a portion of one of the one or more second EPUs and a portion of one of the one or more third EPUs, wherein one of the one or more second EPUs and one of the one or more third EPUs are located furthest from the fuselage among the one or more second EPUs and one or more third EPUs. [3] The electric aircraft according to claim 1, wherein each of the plurality of battery packs is configured to supply its respective parts of the EPUs with power via one or more power buses associated with that battery pack. [4] The electric aircraft according to claim 3, wherein the associated power buses are electrically isolated from each other. [5] The electric aircraft according to claim 1, wherein no two of the plurality of battery packs supply energy to the same part of one of the EPUs. [6] The electric aircraft according to claim 5, wherein each of the EPUs comprises at least two parts, each part being powered by a different battery pack of the plurality of battery packs. [7] The electric aircraft according to claim 1, further comprising: a plurality of first contactors, each assigned to one of the plurality of battery packs, each first contactor being configured to electrically isolate its assigned battery pack from at least those parts of the EPUs to which the battery pack is configured to supply power. [8] The electric aircraft according to claim 7, wherein each first contactor is electrically connected to a positive terminal of the associated battery pack. [9] The electric aircraft according to claim 7, wherein each first contactor is electrically connected to a negative terminal of the associated battery pack. [10] The electric aircraft according to claim 1, further comprising: a plurality of first fuses, each assigned to one of the plurality of battery packs, each first fuse being configured to electrically isolate the assigned battery pack from at least those parts of the EPUs to which the battery pack is configured to supply power. [11] The electric aircraft according to claim 10, wherein each first fuse is electrically connected to a positive terminal of the associated battery pack. [12] The electric aircraft according to claim 1, further comprising: a plurality of second contactors, wherein every second contactor is electrically connected between two battery packs of the plurality of battery packs. [13] The electric aircraft according to claim 12, wherein every second contactor is electrically connected between the positive terminals of the two battery packs. [14] The electric aircraft according to claim 12, wherein the two battery packs are configured to supply energy to different EPUs. [15] The electric aircraft according to claim 12, wherein the two battery packs are configured to supply energy to different parts of one of the EPUs. [16] The electric aircraft according to claim 1, further comprising a plurality of second fuses, wherein each second fuse is electrically connected between two battery packs of the plurality of battery packs. [17] The electric aircraft according to claim 16, wherein every second fuse is electrically connected between the positive terminals of the two battery packs. [18] The electric aircraft according to claim 16, wherein the two battery packs are configured to supply energy to different EPUs. [19] The electric aircraft according to claim 16, wherein the two battery packs are configured to supply energy to different parts of one of the EPUs. [20] The electric aircraft according to claim 1, wherein at least the one or more first EPUs and the one or more third EPUs are tiltable relative to an aircraft wing between a vertical ascent and a forward propulsion configuration. [21] The electric aircraft according to claim 20, wherein the one or more second EPUs and the one or more fourth EPUs are configured to generate lift. [22] The electric aircraft according to claim 1, further comprising two wings arranged on opposite sides of the fuselage, wherein at least some of the EPUs are attached to the wings via booms. [23] The electric aircraft according to claim 22, wherein the two wings are fixed wings. [24] The electric aircraft according to claim 1, wherein the number of EPUs is one of the following: four, six, eight, ten, twelve, fourteen, eighteen and twenty. [25] An electrical system for an aircraft, comprising: a plurality of battery packs configured to power a plurality of electric drive units (EPUs), wherein the plurality of EPUs comprises one or more first EPUs and one or more fourth EPUs; and wherein at least one of the plurality of battery packs is configured to power a portion of one of the first EPUs and a portion of one of the fourth EPUs, wherein the first EPUs are arranged on a first side of at least one axis of symmetry of the plurality of EPUs and the fourth EPUs are arranged on a second side of the at least one axis of symmetry of the plurality of EPUs. [26] The electrical system according to claim 25, wherein the plurality of EPUs comprises: one or more second EPUs arranged on the first side of the at least one axis of symmetry, wherein the one or more first EPUs are arranged in front of the one or more second EPUs; one or more third EPUs arranged on the second side of the at least one axis of symmetry, wherein the one or more third EPUs are arranged in front of the one or more fourth EPUs. [27] The electrical system according to claim 25 or 26, wherein at least one further of the plurality of battery packs is configured to supply energy to a portion of one of the one or more second EPUs and to a portion of one of the one or more third EPUs. [28] The electrical system according to any one of claims 25 to 27, wherein at least one axis of symmetry corresponds to or is parallel to a roll axis of the aircraft.

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