Aircraft with a bus system for supplying electrical power to multiple loads

Abstract

Aircraft (10), preferably a vertical take-off and landing aircraft (10), with (a) a first plurality of loads (2.1, 2.2, ... 2.n) in the form of electric motors for driving rotors and (b) a second plurality of sources (3.1, 3.2, ... 3.n) for supplying the electric motors with electrical energy, wherein (c) the loads (2.1, 2.2, ... 2.n) and sources (3.1, 3.2, ... 3.n) are connected to each other via a bus system (1) such that (d) each of the sources (3.1, 3.2, ... 3.n) is electrically connected to at least one of the loads or each of the loads (2.1, 2.2, ... 2.n) is electrically connected to at least one of the sources via an associated first bus (4.1, 4.2, ... 4.n); and (e) at least a number of the first buses (4.1, 4.2, ... 4.n) are electrically interconnected, wherein (f) at least one current-limiting element (6.1, 6.2, ... 6.n) is connected in the link (5; 5.12, 5.1n, 5.2n).

Description

[0001] The invention, according to claim 1, relates to a preferably vertically launching and landing, most preferably man-carrying aircraft with a first plurality of loads in the form of electric motors for driving rotors and a second plurality of sources for supplying the electric motors with electrical energy, in which the loads and sources are connected to each other via a bus system.

[0002] Furthermore, a method for supplying a first plurality of loads with electrical energy from a second plurality of sources is described for an electrically powered, preferably vertically launching and landing, most preferably man-carrying aircraft.

[0003] In known aircraft of the type mentioned, particularly the Volocopter® 2X from the owner / applicant, electrical loads in the form of motors or rotors are powered by dedicated batteries or accumulators. According to the current design, each battery supplies two motors with electrical energy. Since the Volocopter® 2X has 18 motors / rotors, a total of nine batteries / accumulators are used. For the sake of linguistic simplicity, the following text will refer to motors or loads instead of motors / rotors, and to batteries or sources instead of batteries / accumulators.

[0004] The Volocopter® 2X has no connection between the batteries, so that in the event of a malfunction, only one battery and therefore two motors are "lost", which, due to the large number of motors or batteries available, still ensures safe flight operation.

[0005] It is known from other battery-powered applications to connect batteries directly in parallel to distribute the load evenly between them. In the event of a fault, the entire battery system is switched off, but this is not possible for aircraft like the Volocopter® for safety reasons.

[0006] Alternatively, batteries can be connected via power electronics with DC / DC or DC / AC converters to transfer energy between the sources and balance the load. However, such power electronic components, in the form of voltage converters with complex control units, are relatively heavy, expensive, and prone to failure, making their use in aircraft of the type mentioned impractical.

[0007] However, extensive testing by the owner / applicant has revealed that, depending on the flight mode, wind conditions, or similar factors, using the existing wiring configuration of the motors and batteries can lead to some motors being subjected to a heavier load than others. This causes some batteries to discharge faster than others, potentially forcing the aircraft to land prematurely in extreme cases, even though the remaining batteries would still have sufficient capacity to allow continued flight.

[0008] US patent 2017 / 0267367A1 discloses a person-carrying or cargo-carrying aircraft with rotors driven by electric motors, but does not go into detail about the electrical supply of the motors.

[0009] The invention is based on the objective of further developing an aircraft of the aforementioned type in such a way that, even with uneven loads (especially the loads), a longer supply of electrical energy to the loads and thus a longer flight operation is made possible.

[0010] To solve this problem, the invention proposes a novel interconnection between the individual batteries. According to the invention, the problem is solved by an aircraft with the features of claim 1.

[0011] Advantageous further developments of the invention are the subject of dependent claims.

[0012] In the aircraft according to the invention, preferably capable of vertical take-off and landing, with a first plurality of loads in the form of electric motors for driving rotors and a second plurality of sources of electric motors with electrical energy, the loads and sources are interconnected via a bus system. Most preferably, the aircraft according to the invention is a manned aircraft.

[0013] The bus system connects each of the sources to at least one of the loads or each of the loads to at least one of the sources electrically via an assigned first bus, wherein at least a number of the first buses are electrically interconnected, and wherein at least one current-limiting element is connected in the interconnection.

[0014] A method for supplying a first plurality of loads with electrical energy from a second plurality of sources in an electrically powered, preferably vertically launching and landing, most preferably manned aircraft, provides that in operation each of the sources supplies at least one of the loads with electrical energy via an associated, electrically conductive first bus; and that a differential current equalization between the respective sources takes place between at least a number of the first buses via an electrically conductive connection with at least one current-limiting element.

[0015] As described above, various factors can cause individual power sources, such as batteries, in a typical aircraft to discharge at different rates due to varying loads or electrical loads from electric motors. In extreme cases, this can lead to differences in power or charge levels between individual sources of up to 30%.

[0016] The electrically conductive connection according to the invention of at least a number of the first buses (in the form of power buses between the sources and loads, i.e., in the form of corresponding lines) now makes it possible to compensate for the aforementioned difference between the sources. Such a conductive connection for compensating the source difference can also be referred to as a balancing bus. It is intended to carry only the differential currents between the loads; the significantly larger DC component of the current to each load continues to be supplied directly by the corresponding source via a relevant power bus (first bus).

[0017] Preferably, the individual sources are connected in parallel via a common equalization bus. The current flow in this equalization bus can be throttled to approximately 5 to 20% of the nominal current flowing between the sources and the sinks by means of at least one current-limiting element. So-called PTC thermistors or positive temperature coefficient (PTC) elements can be used as current-limiting elements. These are resistive elements that exhibit a positive temperature coefficient. When such resistive elements are heated by increasing current flow, their resistance increases, resulting in a current-limiting effect. This allows any power differences that may occur between the individual sources to be compensated for and also mitigates (or prevents) short-circuit effects.

[0018] Accordingly, the current-limiting elements can have the additional task of significantly reducing the current flow to the affected location in the event of a possible short circuit, either in a source or on the compensation bus itself, thereby preventing mutual interference between the sources in the event of a fault.

[0019] In contrast to the previously known interconnection of individual sources using power electronic components, the circuit described above, using current-limiting elements in the form of PTC resistors, is particularly simple, self-regulating, and especially lightweight, making it ideal for use in aircraft. It requires no higher-level control or regulation logic, which reduces costs and weight and also significantly simplifies the demonstration of functional safety.

[0020] It has already been pointed out that in the first further development of the aircraft according to the invention it may be provided that a current flow in the connection (of the first buses together) during operation is limited or can be limited to a fraction, for example to about 5% to 20%, of a nominal current which nominal current flows between source and load via the first bus.

[0021] Another embodiment of the aircraft according to the invention provides that at least a number of the sources, preferably all sources, are designed as accumulators. This is also a preferred embodiment for use in an aircraft.

[0022] It has also been pointed out that in further developments of the aircraft according to the invention, it is not necessarily required that a separate power source be provided for each load. Rather, it is within the scope of the invention to assign two or more loads to one power source, and vice versa.

[0023] Preferably, in a further development of the aircraft according to the invention, the current-limiting element is designed as a PTC thermistor, in particular as a PTC resistor. This has already been discussed in detail above.

[0024] Alternatively, the current-limiting element can be designed as an ohmic resistor or as a power electronic current limiter, especially in the form of a so-called chopper circuit, which is significantly lighter and simpler in design than the voltage converters mentioned above.

[0025] It is also within the scope of the invention to combine the two aforementioned embodiments of the current-limiting element as desired, if - advantageously - several current-limiting elements are used.

[0026] In the design of the electrically conductive interconnection of the first buses, it is possible, in an advantageous further development of the aircraft according to the invention, to connect the first buses, preferably all first buses, in pairs and, in particular, cyclically. In at least one of the interconnections, preferably each interconnection, at least one current-limiting element is connected. In this way, a plurality of compensating buses is provided, each of which serves to connect a pair of the first buses and thus also the corresponding sources.

[0027] However, it is also possible to electrically connect a number of the first buses, preferably all of them, via at least one common second bus, with at least one current-limiting element connected to the second bus. Such a configuration can be simpler from a circuit design perspective because only one common equalization bus is required to connect the first buses, rather than multiple connections as described above. Both configurations are equivalent in their fundamental effect, however, since in both cases equalization can occur between the first buses (power buses) and the corresponding sources.

[0028] A preferred further development of the aircraft with a common compensation bus provides that at least one current-limiting element is connected in parallel to at least a number of the first buses, preferably to all first buses, wherein the current-limiting elements are interconnected via the second bus.

[0029] To enable the continued operation of a specific load in the event of a power source failure, without excessive reduction of the available power by a current-limiting element, a highly preferred embodiment of the aircraft according to the invention provides that a switching device is connected in parallel to at least one of the current-limiting elements, preferably to all current-limiting elements, in order to bypass the respective current-limiting element if necessary. In this way, it is possible to prevent the available power from being excessively reduced by the current-limiting element, and the load can continue to be operated even if a corresponding (associated) power source fails.

[0030] The switching device can, for example, be implemented in the form of a simple switch that bridges the corresponding current-limiting element (PTC element) and thus allows an unimpeded current flow.

[0031] In a highly preferred embodiment of the aircraft according to the invention, the switching element is designed as a first diode to further refine this idea. A diode represents a simple form of a possible switching element, familiar to those skilled in the art.

[0032] In a further development of this idea, a variant of the aircraft according to the invention may provide that a second diode is connected in series with the current-limiting element and thus in parallel with the first diode, wherein the first diode and the second diode have opposite forward directions to each other, preferably wherein the first diode is connected in such a way that a current flow from the first bus to the second bus is only possible via the current-limiting element, while the second diode is connected in such a way that a current flow from the second bus to the relevant first bus is possible unhindered.

[0033] In this way, it is ensured that the current flow from the first bus (power bus) between source and load into the equalization bus is guided via a current-limiting element, as is fundamentally intended according to the invention, while conversely, the current flow from the equalization bus into the power bus is possible without hindrance.

[0034] It has already been pointed out that while temperature-dependent resistors in the form of PTC resistors are preferably used as current-limiting elements, conventional (ohmic) resistors or power electronic current limiters in the form of choppers are possible alternatives.

[0035] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings. Fig. Figure 1 shows a circuit diagram of a first design of the bus system; Fig. Figure 2 shows a circuit diagram of a second embodiment of the bus system; Fig. Figure 3 shows a circuit diagram of a third embodiment of the bus system; Fig. Figure 4 shows a circuit diagram of a fourth embodiment of the bus system; and Fig. Figure 5 shows an aircraft according to the invention.

[0036] In Fig. Figure 1 shows a circuit diagram of a first embodiment of the bus system for supplying a first plurality of loads with electrical energy from a second plurality of sources in an electrically powered aircraft, preferably capable of vertical take-off and landing.

[0037] In Fig. As in Figure 1 and the following figures, the bus system is designated by reference numeral 1. It connects a plurality of electrical consumers or loads 2.1, 2.2, ... 2.n with a second plurality of sources 3.1, 3.2, ... 3.n, which sources 3.1, 3.2, ... 3.n provide the electrical energy for the aforementioned loads 2.1, 2.2, ... 2.n. Each of the sources 3.1 to 3.n is electrically connected to at least one of the loads 2.1 to 2.n via an associated first bus 4.1, 4.2, ... 4.n or, more generally, via a first line. According to the illustration in Fig. 1. A first bus 4.1 to 4.n or a corresponding line leads from each of the sources 3.1 to 3.n directly to a respective assigned load 2.1 to 2.n. However, the invention is not limited to such configurations; in particular, it is also possible to connect several sources together with a single, assigned load, or vice versa – for example, two sources with one load, as is the case in a practical implementation of an aircraft from the applicant / proprietor.

[0038] Loads 2.1 to 2.n can be – without restriction – brushless electric motors used to drive the rotors (propellers) of an aircraft. Sources 3.1 to 3.n are preferably rechargeable electrical energy storage devices (batteries or accumulators) designed and intended for supplying electrical power to loads 2.1 to 2.n.

[0039] Furthermore, it is planned that at least a number of the first buses 4.1 to 4.n, according to Fig. 1. All first buses 4.1 to 4.n are electrically interconnected. This is according to Fig. 1. This is achieved via a second bus 5, which connects the first buses 4.1 to 4.n to each other in the manner shown. The connection of the second bus 5 to the first buses 4.1 to 4.n is effected via a current-limiting element in the form of a PTC resistor 6.1, 6.2, ... 6.n. However, the invention is not limited to PTC resistors as current-limiting elements.

[0040] With the in Fig. In the bus system 1 shown, it is possible to compensate for (stored) differences between sources 3.1 to 3.n. The second bus 5 mentioned above thus functions as a balancing bus and is designed to carry differential currents between loads 2.1, 2.2, ... 2.n. A much larger portion of the current to each load 2.1, 2.2, ... 2.n is (still) supplied directly by the respective assigned source 3.1, 3.2, ... 3.n via the associated first bus 4.1 to 4.n. To achieve the aforementioned balancing, the individual sources 3.1 to 3.n are interconnected in parallel via the second bus 5 (balancing bus). The current flow in this balancing bus 5 is throttled to a fraction, preferably to about 5 to 20%, of the nominal current between the sources 3.1 to 3.n and the loads 2.1 to 2.n (or sinks) by means of the current-limiting elements 6.1 to 6.n shown, which are preferably PTC elements.This allows any performance differences that may occur between individual sources 3.1 to 3.n to be compensated for.

[0041] The current-limiting elements 6.1 to 6.n also have the task of significantly reducing the current flow to the affected point in the event of a possible short circuit, either at one of the sources 3.1 to 3.n or at the second bus 5 itself, thereby preventing any mutual interference between the sources 3.1 to 3.n in the event of a fault.

[0042] The advantages and properties of the circuit arrangement described above according to claim 1 also apply in principle to the following in the Fig. 2, Fig. 3 to Fig. 4 alternative embodiments shown.

[0043] In the embodiment according to Fig. 1. If the associated source 3.1 to ... 3.n fails, a load 2.1 to 2.n generally cannot continue to operate because the available power (from the other sources) is significantly reduced by the current-limiting element 6.1 to 6.n. If all loads 2.1 to 2.n are to continue operating even if individual sources 3.1 to 3.n fail, the current-limiting element 6.1 to 6.n must be bypassed in this case. The design according to [reference to relevant section] is suitable for this purpose. Fig. 2.

[0044] The design according to Fig. 2 largely corresponds to the design according to Fig. 1; however, a switch or switching device 7.1, 7.2, ... 7.n is connected in parallel to each current-limiting element 6.1 to 6.n in order to bypass the corresponding current-limiting element 6.1 to 6.n when necessary and thus allow an unimpeded current flow. Suitable switching devices known to those skilled in the art are considered as switching devices 7.1 to 7.n, in particular electromechanical contactors, solid-state power controllers (SSPCs), or circuit breakers. Preferably, the switching devices 7.1, 7.2, ... 7.n are actuated automatically by a higher-level control unit or by the pilot, which is not shown in the figure.

[0045] Fig. Figure 3 shows an alternative embodiment of the circuit arrangement according to Fig. 2, in which diodes are used as switching elements, as shown. According to Fig. In each case, a first diode 8.1, 8.2, ... 8.n is connected in series with the current-limiting element 6.1 to 6.n. In parallel to this series connection of first diode 8.1 to 8.n and current-limiting element 6.1 to 6.n, the switching element 7.1 to 7.n is used instead of the switching element 7.1 to 7.n. Fig. 2 according to Fig. 3. A second diode 8.1', 8.2', ... 8.n' is connected in such a way that the two diodes 8.1, 8.1'; 8.2, 8.2'; ... connected in parallel each other have opposite forward bias directions. In this way, the current flow from the respective first bus 4.1 to 4.n (also referred to as the power bus) between source 3.1 to 3.n and load 2.1 to 2.n is directed into the equalization bus 5 via a current-limiting element 6.1 to 6.n, while conversely, the current flow from the equalization bus 5 into the power bus 4.1 to 4.n is unimpeded.

[0046] Another alternative design is in Fig. Figure 4 illustrates this. Accordingly, it is possible not to connect the current-limiting elements 6.1 to 6.n between the sources 3.1 to 3.n and a common balancing bus 5, but directly between pairs of sources, for example 3.1 and 3.2, as shown in Fig. 3 shown.

[0047] Therefore, in the design according to Fig. 4 compared to the designs of the Fig. 1, Fig. 2 to Fig. 3 the second bus or compensation bus 5; however, compensation between the first buses 4.1 to 4.n or power buses can still take place. For this purpose, the first buses 4.1 to 4.n are connected to each other in pairs by conductive lines, which in Fig. 4 is symbolized by corresponding lines at reference numbers 5.12, 5.1n and 5.2n. A current-limiting element in the form of a PTC resistor 6.1 to 6.n (without limitation) is connected in each of these lines 5.12, 5.1n, 5.2n.

[0048] In conclusion, it shows Fig. 5 schematically the use of a bus system 1, specifically bus system 1 according to Fig. 1 (without limitation), in the case of a specially vertically launching and landing aircraft 10 in the form of a manned multicopter with a plurality of rotors or motors, here in particular 18. However, the invention is not limited to a specific number of motors / rotors. Likewise, the aircraft 10 need not be manned and / or vertically launching and landing.

[0049] According to Fig. Figure 5 shows that the aircraft 10, reference numeral 11, has a cockpit above which a support structure 12 is arranged, which carries the engines and rotors. For clarity, only one rotor is explicitly designated with reference numeral 13. The engines provide the loads according to the Fig. 1, Fig. 2, Fig. 3 to Fig. 4 and accordingly bear the reference number 2. For the sake of clarity, in Fig. 5 only one engine is explicitly named. According to Fig. In section 5, each motor 2 is assigned a source 3 in the form of an electrical energy storage device. For clarity, only one of these sources is explicitly named. The sources 3 and the motors 2 are arranged according to... Fig. 5 are electrically connected to each other via a first bus (power bus), which in Fig. Each connection is represented by a dashed line 4. Again, for clarity, only one of these connections is explicitly labeled. All these (dashed) connections between source 3 and load 2 are analogous to... Fig. 1 connected via a compensation bus (solid line) designated with reference numeral 5. The current-limiting elements, via which the (dashed) lines 4 are connected to the compensation bus, carry in Fig. 5 the (common) reference sign 6.

[0050] In this way, the circuit arrangement can be modified, specifically and without restriction, according to Fig. 1. Use in a vertical take-off and landing aircraft 10. Of course, the expert is aware that the representation according to Fig. Figure 5 should only be understood schematically, because in practical implementation, all sources and loads, or rather, accumulators and motors of the aircraft, will preferably be integrated into the bus system. Furthermore, as already discussed, the design is not limited to assigning each load 2 its own source 3; rather, it may prove advantageous to supply several loads 2 from one source 3 or vice versa.

[0051] Furthermore, the expert readily recognizes that in practice the in Fig. The 5 lines 4, 5 shown will be arranged or laid along the arms or in the arms of the supporting structure 12, from which arms in Fig. 5 only one is designated by reference numeral 14. Furthermore, the sources 3 do not have to be arranged on or in the central area of ​​the supporting structure 12, but can be distributed along the arms 14, preferably directly in the area of ​​the loads (motors) 2.

Claims

[1] Aircraft (10), preferably a vertical take-off and landing aircraft (10), with (a) a first plurality of loads (2.1, 2.2, ... 2.n) in the form of electric motors for driving rotors and (b) a second plurality of sources (3.1, 3.2, ... 3.n) for supplying the electric motors with electrical energy, wherein (c) the loads (2.1, 2.2, ... 2.n) and sources (3.1, 3.2, ... 3.n) are connected to each other via a bus system (1) such that (d) each of the sources (3.1, 3.2, ... 3.n) is electrically connected to at least one of the loads or each of the loads (2.1, 2.2, ... 2.n) is electrically connected to at least one of the sources via an associated first bus (4.1, 4.2, ... 4.n); and (e) at least a number of the first buses (4.1, 4.2, ... 4.n) are electrically interconnected, wherein (f) at least one current-limiting element (6.1, 6.2, ... 6.n) is connected in the link (5; 5.12, 5.1n, 5.2n). [2] Aircraft (10) according to claim 1, in which a current flow in the link (5; 5.12, 5.1n, 5.2n) during operation is limited or can be limited to a fraction of a nominal current, in particular to about 5 to 20% of which nominal current flows between source (3.1, 3.2, ... 3.n) and load (2.1, 2.2, ... 2.n) via the first bus (4.1, 4.2, ... 4.n). [3] Aircraft (10) according to claim 1 or 2, wherein at least a number of the sources (3.1, 3.2, ... 3.n), preferably all sources (3.1, 3.2, ... 3.n), are designed as accumulators. [4] Aircraft (10) according to any one of claims 1 to 3, wherein two or more loads (2.1, 2.2, ... 2.n) are provided per source (3.1, 3.2, ... 3.n). [5] Aircraft (10) according to any one of claims 1 to 4, wherein the current-limiting element (6.1, 6.2, ... 6.n) is designed as a PTC thermistor, in particular as a PTC resistor (6.1, 6.2, ... 6.n). [6] Aircraft (10) according to any one of claims 1 to 4, wherein the current limiting element (6.1, 6.2, ... 6.n) is designed as an ohmic resistor or as a power electronic current limiter. [7] Aircraft (10) according to any one of claims 1 to 6, wherein the first buses (4.1, 4.2, ... 4.n), preferably all first buses (4.1, 4.2, ... 4.n), are linked in pairs, wherein at least one current-limiting element (6.1, 6.2, ... 6.n) is connected in at least one link (5.12, 5.1n, 5.2n), preferably in each link (5.12, 5.1n, 5.2n). [8] Aircraft (10) according to claim 7, wherein the buses (4.1, 4.2, ... 4.n) linked in pairs are cyclically electrically linked to each other. [9] Aircraft (10) according to any one of claims 1 to 6, wherein at least a number of the first buses (4.1, 4.2, ... 4.n), preferably all first buses (4.1, 4.2, ... 4.n), are electrically interconnected via at least one second bus (5), wherein at least one current-limiting element (6.1, 6.2, ... 6.n) is connected in the second bus (5). [10] Aircraft (10) according to claim 9, in which at least one current-limiting element (6.1, 6.2, ... 4.n) is connected in parallel to at least one number of the first buses (4.1, 4.2, ... 4.n), preferably to all first buses (4.1, 4.2, ... 4.n), wherein the current-limiting elements (6.1, 6.2, ... 6.n) are interconnected via the second bus (5). [11] Aircraft (10) according to claim 10, in which a switching device (7.1, 7.2, ... 7.n) is connected in parallel to at least one of the current-limiting elements (6.1, 6.2, ... 6.n), preferably to all current-limiting elements (6.1, 6.2, ... 6.n), in order to bridge the current-limiting element (6.1, 6.2, ... 6.n) when required. [12] Aircraft (10) according to claim 11, in which a first diode (8.1, 8.2, ... 8.n) is provided as switching means (7.1, 7.2, ... 7.n). [13] Aircraft (10) according to claim 12, in which a second diode (8.1', 8.2', ... 8.n') is connected in series with the current-limiting element (6.1, 6.2, ... 6.n) and in parallel with the first diode (8.1, 8.2, ... 8.n), wherein the first diode (8.1, 8.2, ... 8.n) and the second diode (8.1', 8.2', ... 8.n') have opposite forward directions, preferably wherein the first diode (8.1, 8.2, ... 8.n) is connected such that current flow from the first bus (4.1, 4.2, ... 4.n) to the second bus (4.1, 4.2, ... 4.n) is only possible via the current-limiting element (6.1, 6.2, ... 6.n). is, while the second diode (8.1', 8.2', ... 8.n') is connected in such a way that a current flow from the second bus (5) into the relevant first bus (4.1,4.2, ... 4.n) is allowed unhindered.

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