Power distribution system and method in electric aircraft

Abstract

To provide a power distribution system for electric aircraft that provides more excellent power distribution efficiency and weight saving.SOLUTION: An electric aircraft includes: a rotor for providing lift force for vertical taking-off and landing of an aircraft; a prop rotor which can be inclined between lifting force constitution that provides lifting force for vertical taking-off and landing of the aircraft and propulsion constitution that provides forward thrust to the aircraft; a first battery pack for supplying power to the first rotor and the first prop rotor; a second battery pack for supplying power to the second rotor and the second prop rotor; a first power bus which electrically connects the first battery pack to the first rotor and prop rotor; and a second power bus which electrically connects the second battery pack to the second rotor and prop rotor. The second power bus is electrically isolated from the first power bus.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Patent Application No. 16 / 923,939, filed July 8, 2020, the entire contents of which are incorporated herein by reference.

[0002] The field of the invention relates generally to electric aircraft, and more particularly to power distribution for electric aircraft. [Background technology]

[0003] Advances in battery technology have enabled battery power densities suitable for powering lightweight electric aircraft. Power systems for electric aircraft, particularly passenger aircraft, must be safe while simultaneously being both lightweight and efficient. Safety considerations can sometimes conflict with the objectives of reduced weight and high efficiency. For example, conventional power distribution systems often employ multiple battery packs and redundancy within the power distribution system to ensure there are no single points of failure, but this redundancy increases inefficiency and adds weight. Concerns about balancing safety with aircraft weight and efficiency pose challenges in the design of electric aircraft. Summary of the Invention

[0004] According to various embodiments, an electric aircraft includes multiple electric propulsion units and multiple battery packs, each independently powering a different portion of the electric propulsion units. According to various embodiments, a first set of electric propulsion units is a set of rotors that provide lift for the aircraft, and a second set of electric propulsion units is a set of propeller rotors that are tiltable to provide lift in a lift position and forward thrust in a forward thrust position, with each battery pack powering at least a portion of at least one rotor and at least a portion of one propeller rotor. According to various embodiments, the first set of electric propulsion units is positioned forward of the leading edges of a set of wings, and the second set of electric propulsion units is positioned aft of the trailing edges of the set of wings, such that each battery pack powers at least a portion of at least one of the electric propulsion units forward of the wings and at least a portion of at least one of the electric propulsion units aft of the wings. If a battery pack fails during flight, only the portion of the electric propulsion units powered by the battery pack is affected; the remaining electric propulsion units can operate normally because they are powered by the other battery packs. According to various embodiments, each battery pack powers at least a portion of at least one rotor and at least a portion of at least one propeller rotor, such that if a battery pack or its power distribution bus fails during forward flight, only forward power from at least a portion of at least one propeller rotor is lost because at least a portion of at least one rotor is disabled during forward flight and the remaining propeller rotor portions can continue to operate with control surfaces and power adjustments from the remaining propeller rotor portions compensating for the lost propeller rotor portions. According to various embodiments, the battery packs powering different portions of the electric propulsion unit are not electrically connected to each other, thereby eliminating the need for diodes to prevent power from flowing from one battery pack to another and providing greater power distribution efficiency and weight savings compared to architectures in which battery packs are arranged in parallel.

[0005] According to some embodiments, an electric aircraft includes a plurality of rotors for providing lift for vertical takeoff and landing of the aircraft, a plurality of propeller rotors tiltable between a lift configuration for providing lift for vertical takeoff and landing of the aircraft and a propulsion configuration for providing forward thrust to the aircraft, a first battery pack for powering at least a portion of a first rotor of the plurality of rotors and at least a portion of the first propeller rotor of the plurality of propeller rotors, a second battery pack for powering at least a portion of a second rotor of the plurality of rotors and at least a portion of the second propeller rotor of the plurality of propeller rotors, a first power bus electrically connecting the first battery pack to at least a portion of the first rotors and at least a portion of the first propeller rotor, and a second power bus electrically connecting the second battery pack to at least a portion of the second rotors and at least a portion of the second propeller rotor, the second power bus being electrically isolated from the first power bus.

[0006] In some of these embodiments, the first rotor and the first prop rotor may be on opposite sides of the aircraft.

[0007] In some of these embodiments, the first rotor may be powered solely by the first battery pack, and the first prop rotor is powered solely by the second battery pack.

[0008] In some of these embodiments, the first rotor may include at least two motor portions, with the first battery pack powering a first motor portion of the at least two motor portions and the second battery pack powering a second motor portion of the at least two motor portions.

[0009] In some of these embodiments, the electrical circuit connecting the first battery pack to the first rotor and to the first prop rotor may not include a diode.

[0010] In some of these embodiments, the first battery pack may include a multiple battery arrangement in series, parallel, or a combination of series and parallel.

[0011] In some of these embodiments, the first battery pack and the second battery pack may be configured to generate a voltage greater than 100 volts.

[0012] In some of these embodiments, the power of at least one of the first rotor and the first prop rotor may be at least 10 kilowatts.

[0013] In some of these embodiments, the aircraft may be manned.

[0014] In some of these embodiments, the aircraft may be a vertical take-off and landing aircraft.

[0015] According to some embodiments, a method of powering an aircraft includes powering at least a portion of a first rotor and at least a portion of a first prop rotor by a first battery pack via a first power bus electrically connecting the first battery pack to at least a portion of the first rotor and at least a portion of the first prop rotor, and powering at least a portion of a second rotor and at least a portion of the second prop rotor by a second battery pack via a second power bus electrically connecting the second battery pack to at least a portion of the second rotor and at least a portion of the second prop rotor, the second power bus being electrically isolated from the first power bus.

[0016] In some of these embodiments, the first rotor and the first prop rotor may be on opposite sides of the aircraft.

[0017] In some of these embodiments, the method may further include providing lift to the aircraft via the first and second rotors and the first and second prop rotors during vertical takeoff, and providing forward thrust to the aircraft via the first and second prop rotors with the first and second rotors deactivated during cruise.

[0018] In some of these embodiments, the first rotor may be powered solely by the first battery pack.

[0019] In some of these embodiments, the first rotor may include at least two motor portions, with the first battery pack powering a first motor portion of the at least two motor portions and the second battery pack powering a second motor portion of the at least two motor portions.

[0020] In some of these embodiments, the electrical circuit connecting the first battery pack to the first rotor and the first prop rotor may not include a diode.

[0021] In some of these embodiments, the first battery pack may include a multiple battery arrangement in series, parallel, or a combination of series and parallel.

[0022] In some of these embodiments, the first battery pack and the second battery pack may be configured to generate a voltage greater than 100 volts.

[0023] In some of these embodiments, the power of the first rotor may be at least 10 kilowatts.

[0024] In some of these embodiments, the aircraft may be manned.

[0025] According to various embodiments, an electric aircraft includes an airframe, at least one wing connected to the airframe, a first plurality of electric propulsion units attached to the at least one wing and positioned at least partially forward of a leading edge of the at least one wing, a second plurality of electric propulsion units attached to the at least one wing and positioned at least partially aft of a trailing edge of the at least one wing, a first battery pack for powering at least a portion of the first electric propulsion units of the first plurality of electric propulsion units and at least a portion of the first electric propulsion units of the second plurality of electric propulsion units, and a first battery pack for powering at least a portion of the second electric propulsion units of the first plurality of electric propulsion units. a second battery pack for powering at least some of the first electric propulsion units of the first plurality of electric propulsion units and at least some of the second electric propulsion units of the second plurality of electric propulsion units; a first power bus electrically connecting the first battery pack to at least some of the first electric propulsion units of the first plurality of electric propulsion units and at least some of the first electric propulsion units of the second plurality of electric propulsion units; and a second power bus electrically connecting the second battery pack to at least some of the second electric propulsion units of the first plurality of electric propulsion units and at least some of the second electric propulsion units of the second plurality of electric propulsion units, wherein the second power bus is electrically isolated from the first power bus.

[0026] In some of these embodiments, a first electric propulsion unit of the first plurality of electric propulsion units and a first electric propulsion unit of the second plurality of electric propulsion units may be on opposite sides of the aircraft.

[0027] In some of these embodiments, the first plurality of electric propulsion units may include tiltable propeller rotors and the second plurality of electric propulsion units may include fixed rotors.

[0028] In some of these embodiments, a first electric propulsion unit of the first plurality of electric propulsion units may be powered solely by the first battery pack.

[0029] In some of these embodiments, a first electric propulsion unit of the first plurality of electric propulsion units may include at least two motor portions, with the first battery pack powering a first motor portion of the at least two motor portions and the second battery pack powering a second motor portion of the at least two motor portions.

[0030] In some of these embodiments, the electrical circuit connecting the first battery pack to the first electric propulsion unit of the first plurality of electric propulsion units and the first electric propulsion unit of the second plurality of electric propulsion units may not include a diode.

[0031] In some of these embodiments, the first battery pack may include a multiple battery arrangement in series, parallel, or a combination of series and parallel.

[0032] In some of these embodiments, the first battery pack and the second battery pack may be configured to generate a voltage greater than 100 volts.

[0033] In some of these embodiments, the power of a first electric propulsion unit of the first plurality of electric propulsion units may be at least 10 kilowatts.

[0034] In some of these embodiments, the aircraft may be manned.

[0035] In some of these embodiments, the aircraft may be a vertical take-off and landing aircraft.

[0036] According to some embodiments, a method of powering an aircraft includes powering a first plurality of electric propulsion units mounted on at least one wing of the aircraft and positioned at least partially forward of a leading edge of the at least one wing by a first battery pack via a first power bus electrically connecting the first battery pack to at least some of the first electric propulsion units of the first plurality of electric propulsion units and at least some of the first electric propulsion units of a second plurality of electric propulsion units; and powering a second plurality of electric propulsion units mounted on the at least one wing and positioned at least partially aft of a trailing edge of the at least one wing by a second battery pack via a second power bus electrically connecting the second battery pack to at least some of the second electric propulsion units of the first plurality of electric propulsion units and at least some of the second electric propulsion units of the second plurality of electric propulsion units, the second power bus being electrically isolated from the first power bus.

[0037] In some of these embodiments, a first electric propulsion unit of the first plurality of electric propulsion units and a first electric propulsion unit of the second plurality of electric propulsion units may be on opposite sides of the aircraft.

[0038] In some of these embodiments, the first plurality of electric propulsion units may include tiltable propeller rotors and the second plurality of electric propulsion units may include fixed rotors.

[0039] In some of these embodiments, a first electric propulsion unit of the first plurality of electric propulsion units may be powered solely by the first battery pack.

[0040] In some of these embodiments, a first electric propulsion unit of the first plurality of electric propulsion units may include at least two motor portions, with the first battery pack powering a first motor portion of the at least two motor portions and the second battery pack powering a second motor portion of the at least two motor portions.

[0041] In some of these embodiments, the electrical circuit connecting the first battery pack to the first electric propulsion unit of the first plurality of electric propulsion units and the first electric propulsion unit of the second plurality of electric propulsion units may not include a diode.

[0042] In some of these embodiments, the first battery pack may include a multiple battery arrangement in series, parallel, or a combination of series and parallel.

[0043] In some of these embodiments, the first battery pack and the second battery pack may be configured to generate a voltage greater than 100 volts.

[0044] In some of these embodiments, the power of a first electric propulsion unit of the first plurality of electric propulsion units may be at least 10 kilowatts.

[0045] In some of these embodiments, the aircraft may be manned.

[0046] In some of these embodiments, the aircraft may be a vertical take-off and landing aircraft.

[0047] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0048] [Figure 1A] FIG. 1 is a diagram of a VTOL aircraft in a forward flight configuration, in accordance with various embodiments. [Figure 1B] FIG. 1 is a diagram of a VTOL aircraft in a takeoff and landing configuration, according to various embodiments. [Figure 2A] FIG. 1 is a diagram of a power distribution architecture for powering an electric propulsion unit of an aircraft, according to various embodiments. [Figure 2B] FIG. 1 is a diagram of a power distribution architecture for powering an electric propulsion unit of an aircraft, according to various embodiments. [Figure 3]FIG. 1 is a block diagram of a circuit connecting a battery pack to a pair of electric propulsion units, according to various embodiments. [Figure 4] FIG. 1 is a block diagram of a portion of the power distribution to an electric propulsion unit including two partial motors, according to various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0049] According to various embodiments, systems and methods for power distribution in an electric aircraft include powering multiple electric propulsion units (EPUs) of the aircraft with multiple battery packs, each powering different portions of the EPUs using a different power distribution bus. For example, a first battery pack powers a first portion of the EPU using a first power distribution bus, and a second battery pack powers a second portion of the EPU using a second power distribution bus that is electrically isolated from the first power distribution bus. If the first battery pack fails, only the first portion of the EPU is powered down, while the second portion of the EPU continues to be powered by the second battery pack. The EPUs are sized such that the aircraft can continue in controlled flight without at least the first portion of the EPU. By powering different portions of the EPU with different battery packs using different buses, fault-tolerant power distribution can be achieved without the interconnecting battery packs and diodes required by such an architecture, which can result in greater power distribution efficiency and lighter weight.

[0050] According to various embodiments, the multiple EPUs include rotors configured to provide lift to the aircraft, such as during vertical takeoff and landing and hovering, and which can be deactivated during cruise, and propellers that provide lift to the aircraft and can be tilted forward to provide forward thrust to the aircraft for forward flight with lift provided by one or more wings of the aircraft. According to various embodiments, each battery pack powers at least a portion of at least one rotor and at least a portion of at least one propeller, such that if a battery pack or its power distribution bus fails during forward flight, only power from at least a portion of at least one propeller is lost. The other EPU(s), i.e., rotor(s), powered by the lost battery pack do not contribute forward power, so their loss does not affect forward flight. The remaining propeller portions (powered by other battery packs) can continue to operate with adjustments to control surfaces and / or power from the remaining propeller portions to compensate for the lost propeller portions. Thus, the effect of the loss of a battery pack on forward flight can be minimized while still providing fault tolerance without the added weight associated with diodes and / or redundant power distribution buses. According to various embodiments, each battery pack powers the equivalent of one prop rotor (in addition to some rotors), such that the forward power loss to forward flight due to the loss of a battery pack is only the equivalent of the power from one prop rotor.

[0051] According to various embodiments, the aircraft is an electric vertical take-off and landing (VTOL or eVTOL) aircraft, which can take off and land vertically and hover, providing the ability to bring travelers closer to their destinations than with aircraft that require runways. According to various embodiments, the aircraft is a fixed-wing eVTOL.

[0052] According to various embodiments, the EPUs powered by a given battery pack are selected to reduce the destabilizing effects caused by loss of power to the EPU if the battery pack fails. EPUs located on either side of one or more axes of symmetry of the EPU cluster can be powered by the same battery pack to reduce roll, pitch, or yaw moments that may be caused by loss of power to the EPUs powered by the battery pack. For example, EPUs in the same relative positions on either side of the aircraft's longitudinal axis may be powered by a first battery pack, so that if one of the battery packs fails, the thrust provided by the remaining EPUs is still uniform about the longitudinal axis, resulting in minimal roll moments. Similarly, in some embodiments, EPUs may be located forward and aft of a set of wings, with the EPUs on either side of the wing and on either side of the longitudinal axis powered by the same battery pack.

[0053] According to various embodiments, the portion of the EPU powered by the battery pack may include a portion of a single EPU motor, with one portion of the EPU motor powered by a first battery pack and another portion of the EPU motor powered by a second battery pack. For example, the EPU may include two half motors that can cooperate during normal operation to drive multiple blades to provide thrust for the aircraft, with one half motor powered by one battery pack and the other half motor powered by another battery pack. If one battery pack fails, the EPU can still operate at half power. A given battery pack can power the partial motors of different EPUs, allowing the effect of the loss of a battery pack to be shared among multiple EPUs that continue to operate at reduced power.

[0054] In the following description of the disclosure and embodiments, reference is made to the accompanying drawings which show, by way of illustration, specific embodiments which may be practiced. It will be understood that other embodiments and examples may be practiced and that changes may be made without departing from the scope of the disclosure.

[0055] It will further be understood that, as used in the following description, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or," as used herein, will also be understood to refer to and include all possible combinations of one or more of the associated listed items. It will further be understood that, as used herein, the terms "comprise," "including," "comprises," and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, components, and / or units, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, units, and / or groups thereof.

[0056] As used herein, the term "prop rotor" refers to a controllable pitch propeller that can provide thrust for vertical lift and for forward propulsion by varying the pitch of the propeller.

[0057] As used herein, the term "battery pack" means any combination of electrically connected batteries (i.e., battery cells) and may include multiple battery arrangements in series, parallel, or a combination of series and parallel.

[0058] 1A and 1B illustrate a VTOL aircraft 100 in a cruise configuration and a vertical take-off and landing configuration, respectively, according to various embodiments. Exemplary embodiments of a VTOL aircraft according to various embodiments are described in U.S. Patent Application No. 16 / 878,380, entitled "Vertical Take-Off and Landing Aircraft," filed May 19, 2020, the entire contents of which are incorporated herein by reference.

[0059] The aircraft 100 includes an airframe 102, wings 104 attached to the airframe 102, and one or more aft stabilizers 106 attached to the rear of the airframe 102. The aircraft 100 includes multiple rotors 112 and multiple propeller rotors 114 (collectively referred to herein as EPUs). The EPUs (112, 114) generally include electric motors that drive fans (multiple blades) and motor controllers for controlling / powering the motors. As discussed further below with respect to FIG. 4, the EPU may include multiple partial motors that can independently and collectively drive fans and can be controlled by multiple separate motor controllers.

[0060] Rotor 112 is attached to wing 104 and configured to provide lift for vertical takeoff and landing. Prop rotor 114 is attached to wing 104 and is tiltable between a lift configuration that provides a portion of the lift required for vertical takeoff, landing, and hovering, as shown in FIGURE 1B, and a propulsion configuration that provides forward thrust to the aircraft 100 for horizontal flight, as shown in FIGURE 1A. As used herein, prop rotor lift configuration refers to any prop rotor orientation in which the prop rotor thrust is primarily providing lift to the aircraft, and prop rotor propulsion configuration refers to any prop rotor orientation in which the prop rotor thrust is primarily providing forward thrust to the aircraft.

[0061] According to various embodiments, rotors 112 are configured to provide only lift, with all thrust being provided by the prop rotors. Thus, rotors 112 can be in a fixed position. During takeoff and landing, prop rotors 114 are tilted into a lift configuration in which their thrust is directed downward to provide additional lift.

[0062] For forward flight, the prop rotors 114 are tilted from a lift configuration to a thrust configuration. In other words, the pitch of the prop rotors 114 is changed from a pitch in which the prop rotor thrust is directed downward to provide lift during vertical takeoff and landing and during hovering to a pitch in which the prop rotor thrust is directed rearward to provide forward thrust to the aircraft 100. The prop rotors are tilted about an axis 118 that is perpendicular to the forward direction of the aircraft 100. When the aircraft 100 is in full forward flight, lift may be provided entirely by the wings 104 and the rotors 112 may be stationary. The blades 120 of the rotors 112 may be locked in a low-drag position for aircraft cruise. In some embodiments, the rotors 112 each have two blades 120 that are locked in a minimum-drag position for cruise, with one blade directly in front of the other, as shown in FIG. 1A . In some embodiments, the rotors 112 have more than two blades. In some embodiments, the prop rotors 114 include more blades 116 than the rotors 112. For example, as shown in Figures 1A and 1B, the rotors 112 may each include two blades, and the prop rotors 114 may each include five blades. According to various embodiments, the prop rotors 114 may have between two and five blades.

[0063] According to various embodiments, the aircraft includes only one wing 104 on each side of the fuselage 102 (or a single wing extending across the entire aircraft), with at least a portion of the rotors 112 located aft of the wing 104 and at least a portion of the prop rotors 114 located forward of the wing 104. In some embodiments, all of the rotors 112 are located aft of the wing 104 and all of the prop rotors are located forward of the wing 104. According to some embodiments, all of the rotors 112 and prop rotors 114 are wing-mounted, i.e., none of the rotors or prop rotors are mounted to the aircraft. According to various embodiments, all of the rotors 112 are positioned aft of the wing 104 and all of the prop rotors 114 are positioned forward of the wing 104. According to some embodiments, all of the rotors 112 and prop rotors 114 are positioned inboard of the wing tips 109.

[0064] According to various embodiments, the rotors 112 and the prop rotors 114 are attached to the wings 104 by booms 122. The booms 122 may be attached below the wings 104, above the wings, and / or integrated within the airfoil. According to various embodiments, one rotor 112 and one prop rotor 114 are attached to each boom 122. The rotors 112 may be attached to the aft ends of the booms 122, and the prop rotors 114 may be attached to the forward ends of the booms 122. In some embodiments, the rotors 112 are attached to the booms 122 in fixed positions. In some embodiments, the prop rotors 114 are attached to the forward ends of the booms 122 via hinges 124. The prop rotors 114 may be attached to the booms 122 such that they are aligned with the main body of the booms 122 when the prop rotors 114 are in their propulsion configuration, forming a continuous extension of the forward ends of the booms 122 that minimizes drag for forward flight.

[0065] According to various embodiments, the aircraft 100 may include only one wing on each side of the aircraft 100 or a single wing extending across the entire aircraft. According to some embodiments, at least one wing 104 is a high wing attached to the upper side of the fuselage 102. According to some embodiments, the wing includes control surfaces such as flaps and / or ailerons. According to some embodiments, the wing may have curved wing tips 109 for reduced drag during forward flight.

[0066] According to some embodiments, the aft stabilizer 106 includes control surfaces such as one or more rudders, one or more elevators, and / or one or more combined rudder-elevators. The wing(s) may have any suitable design. In some embodiments, the wing has a tapered leading edge 123, as shown in the embodiment of FIG. 1A, for example. In some embodiments, the wing has a tapered trailing edge.

[0067] FIG. 2A illustrates a power distribution architecture for powering EPUs (112, 114) of an aircraft 100 according to various embodiments. While FIGS. 1A-2A illustrate 12 EPUs (numbered 1-12 in FIG. 2A ) mounted on the wing 104, an aircraft according to various embodiments may have any suitable number of EPUs, including 4, 6, 8, 10, 14, 18, 20, or more. The EPUs are powered by multiple battery packs 200. In the embodiment shown in FIG. 2A , there are six battery packs 200, numbered 1-6. Each battery pack 200 powers only a portion of the EPUs. In the illustrated embodiment, each battery pack 200 powers two EPUs. The grouping of battery packs and EPUs according to the embodiment shown in FIG. 2A is listed in FIG. 2B . Battery pack 1 powers EPUs 1 and 12, battery pack 2 powers EPUs 2 and 11, and so on. Each battery pack 200 is connected to a respective portion of the EPU via a dedicated power distribution bus, e.g., buses 202, 204. Thus, the power distribution bus 202 of one battery pack 1 is not electrically connected to the power distribution bus 204 of battery pack 2.

[0068] Because the battery packs 200 are electrically isolated from each other, an electrical failure in one battery pack or its power distribution does not affect the operation of the other EPUs and battery packs. Only the EPU powered by the failed battery pack or power distribution is affected. Thus, there is no single point of failure in the aircraft's power supply. Furthermore, because the battery packs and power distribution circuits are isolated from each other, diodes are not required to prevent current from flowing from one battery pack to another. This can result in significant weight savings and increased efficiency compared to systems with parallel battery packs.

[0069] According to various embodiments, the particular EPUs powered by a given battery pack can be selected to reduce the destabilizing effects caused by loss of power to the EPU if the battery pack fails. According to various embodiments, EPUs located on either side of one or more axes of symmetry of the EPU cluster can be powered by the same battery pack to reduce roll, pitch, or yaw moments that may be caused by loss of power to the EPUs powered by the battery pack. For example, EPUs in the same relative positions on either side of the aircraft's longitudinal axis 280 can be powered by a first battery pack, so that if one of the battery packs fails, minimal roll moments will occur because the thrust provided by the remaining EPUs will be uniform about the longitudinal axis. Similarly, in some embodiments, a set of EPUs may be positioned at least partially forward of the leading edges of a pair of wings and a set of EPUs may be positioned at least partially aft of the trailing edges of a pair of wings, and the EPUs on both sides of the wings and on both sides of the longitudinal axis 280 may be powered by the same battery pack, such that minimal roll and pitch moments occur in the event of a battery pack failure (as shown in FIG. 2A ).

[0070] According to various embodiments, each battery pack 200 powers at least a portion of at least one prop rotor 114 and at least a portion of at least one rotor 112. In the embodiment of FIG. 2A , the rotors and prop rotors in the bilateral positions are powered by the same battery pack 200. Thus, the outermost prop rotor 114 on the left side of the aircraft's airframe 102 (EPU 1 in FIG. 2A ) is powered by the same battery pack (battery pack 1 in FIG. 2A ) as the outermost rotor 112 on the right side of the airframe 102 (EPU 12). Similarly, the other pair of outermost EPUs (EPU 6 and EPU 7 in FIG. 2A ) are powered by the same battery pack (battery pack 6). Grouping need not be limited to EPUs in diametrically opposed positions. For example, EPU 1 could be grouped with EPU 11 instead of EPU 12.

[0071] The number of EPUs powered by a given battery pack may be greater than two. For example, in some embodiments, the number of EPUs per battery pack may be three, four, five, six, or any other suitable fraction of the total number of EPUs. According to various embodiments, there may be a different number of EPUs in each group. For example, one group may have two EPUs (two EPUs powered by a battery pack) and another group may have four EPUs (four EPUs powered by different battery packs). The number of battery packs may be only two. In various embodiments, the number of battery packs is at least three, at least four, at least five, at least six, at least seven, at least eight, or more.

[0072] FIG. 3 is a block diagram of a circuit connecting a single battery pack 300 to a pair of EPUs 302 and 304 according to various embodiments. EPU 302 can be, for example, EPU1 of FIG. 2A, and EPU 304 can be, for example, EPU12 of FIG. 2A. Battery pack 300 is connected to EPUs 302 and 304 via a power distribution bus 306. Multiple fuses are provided to protect the components in the event of an electrical fault. Two fuses 308 and 310 are provided to disconnect EPUs 302 and 304, respectively, in the event of a power surge associated with each. Fuse 312 is located immediately downstream of battery pack 300. Fuse 312 has a higher current rating than fuses 308 and 310 because it handles power for both EPUs. According to various embodiments, a small fuse 314 is located between the battery pack and a charging circuit (not shown).

[0073] According to various embodiments, a contactor 316 may be provided to connect / disconnect the positive terminal of the battery pack 300 to / from the EPU. According to various embodiments, the contactor 316 may be used to disconnect the EPU from power, such as when the aircraft is on the ground. According to various embodiments, the contactor 316 is manually operated, such as via a manual switch located in the aircraft cockpit. In some embodiments, a similar contactor 318 is also provided on the negative terminal side.

[0074] In some embodiments, the EPU, or at least a portion of the EPU, includes multiple motor stages, each independently powered by a different battery pack, so that if one battery pack fails, only the portion of the EPU is powered down and the EPU can continue to operate at a reduced power level. FIG. 4 is a block diagram of a portion of the power distribution to an EPU 400, including two partial motors, 402A and 402B. The EPU 400 may be a rotor, such as the rotor 112 of FIG. 1A, or a prop rotor, such as the prop rotor 114 of FIG. 1A. The two partial motors 402A and 402B can operate independently to drive fan blades 404 via a shaft 406, or can operate simultaneously to drive the fan blades 404 at a higher power. The partial motors 402A and 402B are driven by their own motor controllers 408A and 408B, respectively. The partial motor 402A and motor controller 408A are powered by the battery pack 450 via the power distribution bus 460, and the partial motor 402B and motor controller 408B are powered by the battery pack 452 via the power distribution bus 462. The partial motor 402A, motor controller 408A, power distribution bus 460, and battery pack 450 are electrically isolated from the partial motor 402B, motor controller 408B, power distribution bus 462, and battery pack 452. Thus, an electrical fault affecting the first partial motor 402A does not affect the second partial motor 402B, and vice versa. Thus, the EPU 400 can continue to operate, albeit at reduced power, if one of the battery packs 450 or 452 fails.

[0075] According to various embodiments, the battery packs can drive the partial motors of the EPUs located on both sides. For example, referring to FIG. 2A, a first battery pack 1 can power the first partial motor of EPU 1, the first partial motor of EPU 12, the first partial motor of EPU 6, and the first partial motor of EPU 7. Thus, in the event of a failure of battery pack 1, both rotors and prop rotors in the same relative position on both sides of the aircraft will lose at least half of their maximum available power but will still be operational.

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

[0077] According to various embodiments, each battery pack is configured 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 up to 200 kilowatt-hours, preferably up to 100 kilowatt-hours, preferably up to 75 kilowatt-hours, or more preferably up to 50 kilowatt-hours. According to various embodiments, the battery packs are configured so that their collective maximum stored energy is at least 1 kilowatt-hour or preferably at least 10 kilowatt-hours and / or so that their maximum stored energy is up to 200 kilowatt-hours, preferably up to 100 kilowatt-hours, preferably up to 75 kilowatt-hours, or more preferably up to 50 kilowatt-hours. According to various embodiments, at least some of the battery packs at full charge provide at least 100 volts, at least 500 volts, or at least 1000 volts. According to various embodiments, at least some of the battery packs at full charge provide up to 2000 volts, up to 1500 volts, up to 1000 volts, or up to 500 volts. According to some embodiments, the nominal maximum voltage is between 500 and 1000 volts, preferably between 600 and 800 volts, or more preferably between 650 and 750 volts.

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

[0079] Aircraft according to the above principles can be configured to carry at least one human and up to ten humans, preferably up to six humans, and more preferably up to four humans. According to some embodiments, the aircraft is configured to be piloted and includes piloting controls. In some embodiments, the aircraft is configured to operate autonomously without an onboard pilot and with or without one or more passengers.

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

[0081] According to various embodiments, the rotor 112 and / or prop rotor 114 are configured to have a relatively low tip speed to reduce the amount of noise generated by the aircraft. In some embodiments, the tip speed of the rotor blades is approximately 0.4 Mach when hovering. According to various embodiments, the diameter of the rotor and / or prop rotor 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, more preferably in the range of 6 to 10 meters.

[0083] According to various embodiments, the aircraft is operated during takeoff and landing by positioning the prop-rotors in a lift configuration and providing the aircraft with the required lift through the rotors and the combined lift provided by the prop-rotors. According to various embodiments, during vertical takeoff, landing, and / or hovering, the prop-rotors may be maintained in a predetermined lift configuration, which may be the same for all prop-rotors or different for different prop-rotors. According to various embodiments, the pitch of at least some of the prop-rotors may be actively adjusted during takeoff, landing, and / or hovering to provide required stability and / or controllability. According to some embodiments, the pitch of at least one prop-rotor is actively controlled by a flight controller during takeoff, landing, and / or hovering to generate a yaw moment.

[0084] According to various embodiments, each rotor and / or each prop-rotor can be independently controlled by a flight controller according to various degrees of freedom of movement. According to various embodiments, the only rotor degree of freedom is the rotor's rotational speed. In some embodiments, the angle of attack of the rotor's blades can be adjusted collectively, providing an additional degree of freedom. According to various embodiments, at least some of the prop-rotor's degrees of freedom include the prop-rotor's rotational speed, the blade's collective angle of attack, and the prop-rotor's pitch. According to various embodiments, any of these degrees of freedom can be actively controlled by the flight controller (autonomously or in response to a pilot's command) during takeoff and landing to provide appropriate stability and controllability.

[0085] Once the aircraft reaches a sufficient altitude to begin forward flight, the prop rotors begin to tilt forward into their propulsion configuration so that their thrust provides a combination of lift and thrust, with the lift ratio decreasing as the prop rotors are further tilted into their propulsion configuration. The rotors may remain active for at least a portion of the time that the prop rotors are tilted forward so that they continue to provide rotor-based lift. The rotors may be deactivated any time after the forward airspeed is high enough for the wings to provide enough lift to maintain the aircraft's altitude. As described above, the rotor blades may be locked in a low-drag position.

[0086] During cruise, the rotors remain deactivated. Control surfaces on the wings and / or aft stabilizer can be used in a conventional manner for aircraft control and stability. According to some embodiments, if a battery pack is lost during forward flight, resulting in a loss of power provided by the portion of the prop rotor powered by the lost battery pack, the aircraft can compensate through the use of control surfaces and / or through the adjustment of power from the unaffected portion of the prop rotor.

[0087] According to some embodiments, the tilt of at least some of the proprotors can be actively controlled to provide additional stability and / or maneuverability control. In some embodiments, the tilt of at least some of the proprotors is actively controlled during takeoff, landing, and / or hovering. In some embodiments, the tilt of the proprotors is fixed (i.e., non-variable) during cruise. According to some embodiments, the tilt of the outermost proprotor can be actively and independently controlled during vertical takeoff, landing, and / or hovering to provide yaw moment as needed.

[0088] According to various embodiments, EPUs (rotors and propellers) can be powered by the power distribution architecture described herein. For example, a method of powering an aircraft includes supplying electricity by a first battery pack to a first plurality of electric propulsion units mounted on at least one wing of the aircraft and positioned at least partially forward of a leading edge of the at least one wing via a first power distribution bus that electrically connects the first battery pack to at least some of the first electric propulsion units of the first plurality of electric propulsion units and at least some of the first electric propulsion units of a second plurality of electric propulsion units. The method also includes supplying electricity by a second battery pack to a second plurality of electric propulsion units mounted on the at least one wing and positioned at least partially aft of a trailing edge of the at least one wing via a second power distribution bus that electrically connects the second battery pack to at least some of the second electric propulsion units of the first plurality of electric propulsion units and at least some of the second electric propulsion units of the second plurality of electric propulsion units. The second power distribution bus is electrically isolated from the first power distribution bus.

[0089] According to various embodiments, a method of powering an aircraft includes powering at least a portion of a first rotor and at least a portion of a first prop rotor by a first battery pack via a first power bus electrically connecting the first battery pack to at least a portion of the first rotor and at least a portion of the first prop rotor. The method also includes powering at least a portion of a second rotor and at least a portion of the second prop rotor by a second battery pack via a second power bus electrically connecting the second battery pack to at least a portion of the second rotor and at least a portion of the second prop rotor. The second power bus is electrically isolated from the first power bus.

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

[0091] According to various embodiments, the battery packs power different motor sections of the same EPU, so that if the battery pack or one of its power distributions is lost, the affected EPU can continue to operate at reduced power. According to various embodiments, the power of the unaffected motor sections can be increased and / or the power of the unaffected EPU can be increased to compensate for the loss of thrust from the disabled motor section.

[0092] The foregoing description has been described with reference to specific embodiments for purposes of explanation. However, the illustrative discussion above is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the technology and their practical application. Others skilled in the art will thereby be able to best utilize the technology and various embodiments, and various modifications as may be suited to the particular application under consideration.

[0093] Although the disclosure and examples have been fully described with reference to the accompanying drawings, it should be noted that various modifications and variations will be apparent to those skilled in the art. Such modifications and variations will be understood to be included within the scope of the disclosure and examples as defined by the claims. Finally, the entire disclosures of the patents and publications referenced in this application are incorporated herein by reference.

Claims

1. 1. An electric aircraft, comprising: The aircraft and two wings disposed on either side of the fuselage; a plurality of first electric propulsion units (EPUs) disposed on either side of the airframe, the first EPUs being aft of the wings during forward flight; a plurality of second EPUs disposed on either side of the airframe and forward of the wings during forward flight, the plurality of second EPUs being tiltable between a vertical lift configuration and a forward thrust configuration; A plurality of battery packs, each battery pack comprising at least: a portion of one of the first EPUs on one side of the airframe; and a portion of one of the second EPUs on the other side of the fuselage; a battery pack configured to power the An electric aircraft comprising:

2. One of the battery packs includes at least a portion of one of the first EPUs located furthest from the longitudinal axis of the airframe and on one side of the airframe; and a portion of one of the second EPUs located furthest from the longitudinal axis of the airframe and on the other side of the airframe; The electric aircraft of claim 1 , configured to power

3. 3. The electric aircraft of claim 2, wherein one of the battery packs is configured to power a respective portion of one of the first EPUs and a respective portion of one of the second EPUs via a dedicated power distribution bus for that battery pack.

4. The electric aircraft of claim 3 , wherein the dedicated power distribution buses are electrically isolated from each other.

5. One of the battery packs includes at least a portion of one of the first EPUs located closest to the longitudinal axis of the airframe and on one side of the airframe; and a portion of one of the second EPUs located closest to the longitudinal axis of the airframe and on the other side of the airframe; The electric aircraft of claim 1 , configured to power

6. the number of first EPUs is six, three of the first EPUs are adjacent to one side of the wing and three of the first EPUs are adjacent to the other side of the wing; the number of second EPUs is six, three of the second EPUs are adjacent to one side of the wing and three of the second EPUs are adjacent to the other side of the wing; One of the battery packs includes at least a portion of one of the first EPUs disposed between two other first EPUs adjacent one of the wings; and a portion of one of the second EPUs disposed between two other second EPUs adjacent the other of the wing; configured to power the The electric aircraft of claim 1 .

7. 7. The electric aircraft of claim 6, wherein one of the battery packs is configured to power, via a dedicated power distribution bus for that battery pack, at least a portion of one of the first EPUs located between two other first EPUs adjacent one of the wings and a portion of one of the second EPUs located between two other second EPUs adjacent the other of the wings.

8. The electric aircraft of claim 7 , wherein the dedicated power distribution buses are electrically isolated from each other.

9. 2. The electric aircraft of claim 1, wherein each battery pack is configured to power at least a portion of one of the first EPUs adjacent one of the wings and a portion of one of the second EPUs adjacent the other of the wings via a dedicated power distribution bus for that battery pack.

10. The electric aircraft of claim 9 , wherein the dedicated power distribution buses are electrically isolated from each other.

11. The electric aircraft of claim 1 , wherein no two of the battery packs power the same portion of any one of the first EPUs.

12. The electric aircraft of claim 11 , wherein at least two of the battery packs power different portions of one of the first EPUs.

13. The electric aircraft of claim 1 , wherein no two of the battery packs power the same portion of any one of the second EPUs.

14. The electric aircraft of claim 13 , wherein at least two of the battery packs power different portions of one of the second EPUs.

15. The electric aircraft of claim 1 , wherein no two of the battery packs power the same portions of any one of the first EPUs and any one of the second EPUs.

16. The electric aircraft of claim 15 , wherein at least two of the battery packs power different portions of one of the first EPUs and one of the second EPUs.

17. The electric aircraft of claim 1 , wherein each first EPU is powered by only one of the battery packs.

18. The electric aircraft of claim 1 , wherein each second EPU is powered by only one of the battery packs.

19. The electric aircraft of claim 1 , wherein each first EPU and each second EPU is powered by only one of the battery packs.

20. a plurality of contactors, each contactor configured to electrically isolate one of the battery packs from at least a portion of one of the first EPUs adjacent one of the wings and a portion of one of the second EPUs adjacent the other of the wings that the battery pack is configured to power; The electric aircraft of any one of claims 1 to 19, further comprising:

21. 21. The electric aircraft of claim 20, wherein each contactor is electrically coupled to a positive terminal of an associated battery pack.

22. 22. The electric aircraft of claim 21, wherein each contactor is electrically coupled to a negative terminal of an associated battery pack.

23. a plurality of fuses, each configured to electrically isolate one of the battery packs from at least a portion of one of the first EPUs adjacent one of the wings and a portion of one of the second EPUs adjacent the other of the wings that the battery pack is configured to power; The electric aircraft of any one of claims 1 to 19, further comprising:

24. 24. The electric aircraft of claim 23, wherein each fuse is electrically coupled to a positive terminal of an associated battery pack.

25. The electric aircraft of any one of claims 1 to 19, wherein the first EPU is attached to the wing via a boom.

26. The electric aircraft of any one of claims 1 to 19, wherein the second EPU is attached to the wing via a boom.

27. The electric aircraft of any preceding claim, wherein the plurality of first EPUs are configured to provide lift.

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