Electric propulsion system for an aerial vehicle, an aerial vehicle incorporating such an electric propulsion system

Abstract

The present invention relates to an electric propulsion system (20) for an aerial vehicle, comprising a plurality of electric motors (21), a plurality of power batteries (22) for supplying said electric motors with electrical energy, and an electrical distribution network connecting said power batteries to the electric motors, said electric propulsion system (20) further comprising a backup battery (25), adapted to be connected to the electric motors via the electrical distribution network, and said electric propulsion system is configured to supply the electric motors in at least two different supply modes: a normal supply mode, in which the backup battery (25) does not supply any of the electric motors (21), said electric motors being supplied by the power batteries (22), and a backup supply mode.in which the backup battery (25) powers at least one electric motor (21). Figure 2.

Description

Description Title of the invention: Electric propulsion system for an aerial vehicle, aerial vehicle comprising such a propulsion system electric technical field

[0001] = The present invention belongs to the field of self-propelled aerial vehicles electric or hybrid, and relates more specifically to a propulsion system electric for such aerial vehicles. State of the art

[0002] = Nowadays, there are more and more aerial vehicles equipped with systems of Electric propulsion. This is particularly the case for aerial vehicles without passengers (unmanned aerial vehicle or UAV in Anglo-Saxon literature) such than drones, or even for passenger aircraft, for example for urban mobility (flying taxis, etc.).

[0003] — An electric propulsion system for an aerial vehicle uses several motors electrical systems to ensure the takeoff, flight, and landing of the aerial vehicle. Electric motors are powered by power batteries which allow to ensure the necessary electrical energy reserve for the duration of the mission aerial vehicle.

[0004] — Figure 1 schematically represents an example of a propulsion system 10 electrical according to the prior art.

[0005] = As illustrated by [Fig.1], the electric propulsion system 10 comprises several electric motors 11 powered by several power supply batteries 12. The 11 electric motors are connected to the power supply batteries by a network of electrical distribution. In the example illustrated in [Fig. 1], each battery The 12V power supply, in principle, powers two electric motors, and the DC network... electrical distribution incorporates reconfiguration mechanisms allowing, in case of failure of a power supply battery (for example in case of insufficient charging of this one), to connect the electric motors that were powered by the battery from a failing power supply to other, non-failing power supplies. Such Reconfiguration mechanisms therefore allow for maintaining control of the vehicle aerial in the event of a power supply battery failure, in particular to allow to perform a safe emergency landing.

[0006] — However, the known architectures of electric propulsion systems for Aerial vehicles, such as the architecture illustrated in [Fig. 1], require a perfect knowledge of the electrical energy available in each battery power supply to ensure a safe mission, Indeed, the electrical energy available in each power supply battery must be able to be estimated with sufficient accuracy to be able to indicate with good reliability to an aerial vehicle user the autonomy of said aerial vehicle, so that the user can plan the aerial vehicle mission and know when he will have to make a landing. In practice, accurately estimating the available electrical energy in a power supply battery is difficult because it depends on numerous parameters, including the environment (temperature, humidity, etc.) and the battery's usage history. Furthermore, the accuracy of estimating the available electrical energy in a power supply battery tends to decrease with the battery's charge level. In other words, the less electrical energy is available in a power supply battery, the more difficult it is to obtain a precise estimate of that available electrical energy. In practice, due to the uncertainty in estimating the electrical energy available in each power battery, it is necessary to define and maintain a significant electrical energy margin to ensure sufficient available power for an emergency landing procedure, despite this uncertainty. This margin is all the more critical because, in the event of a power battery failure, a limited number of batteries must power all the electric motors. The need for a substantial margin also necessitates increasing the aircraft's onboard mass. Description of the invention The purpose of this disclosure is to address all or part of the limitations of prior art solutions, including those described above, by proposing a solution that reduces the required electrical energy margin and ensures that, in the event of a power supply battery failure, the remaining electrical energy is sufficient to perform emergency maneuvers, including an emergency landing. To this end, and according to a first aspect, an electric propulsion system for an aerial vehicle is proposed, comprising a plurality of electric motors, a plurality of power batteries to supply said electric motors with electrical energy, and an electrical distribution network connecting said power batteries to the electric motors. This electric propulsion system further includes an additional power battery, referred to as a backup battery, adapted to be connected to the electric motors via the distribution network. electric, and said electric propulsion system is configured to power the electric motors according to at least two different power supply modes: a so-called normal power supply mode, in which the backup battery does not power any of the electric motors, said electric motors being powered by the power supply batteries, a backup power supply mode, in which the backup battery powers at least one electric motor. Thus, the electric propulsion system is configured to power the electric motors in at least two different power modes, namely a normal propulsion mode used by default during takeoff, flight and landing phases, and a backup power mode used when at least one power battery fails (power battery malfunction or low charge level). In addition, the electric propulsion system according to this disclosure includes an additional power supply battery, referred to as a backup battery, which is not used in the normal power supply mode, and which is used only in the backup power supply mode, to take over from a failing power supply battery. Thus, in the event of a failure of the main power battery, it can be replaced by the backup battery. Since the backup battery is not used in normal power mode, its charge level is generally at its maximum when the electric propulsion system switches to backup power mode, so its electrical energy content is known with good accuracy. By sizing the backup battery to power the electric motors for a predetermined duration sufficient to perform at least one emergency landing, the margin of electrical energy carried by the aircraft can be significantly reduced compared to prior art solutions.Indeed, prior art solutions require a margin for each backup battery because each backup battery can be used to compensate for the failure of another backup battery, at a time when the potentially low charge level does not allow for an accurate estimation of the electrical energy available in each backup battery. According to the present disclosure, the backup battery can power all the electric motors, and when it begins to be used (i.e., at the start of the emergency situation created by the failure of a backup battery), the backup battery always has a maximum charge level that allows for an accurate determination of the available electrical energy. In certain embodiments, the electric propulsion system can may also include one or more of the following optional features, taken individually or in all technically possible combinations. In particular embodiments, the electric propulsion system includes a power supply battery failure detection module and a control module configured to implement the normal power supply mode when no power supply battery failure is detected and to implement the backup power supply mode when a failure of at least one power supply battery is detected. In particular embodiments, the electrical distribution network includes first switching means adapted to connect / disconnect the backup battery from the electric motors, and the control module is configured to control the first switching means for: In normal power mode: disconnect the backup battery from electric motors, In backup power mode: connect the backup battery to the minus an electric motor. In particular embodiments, the electrical distribution network further includes secondary switching means adapted to connect / disconnect the power supply batteries to the electric motors, and the control module is configured to control the secondary switching means for: In normal power mode: connect the power supply batteries to electric motors, In backup power mode: disconnect each battery power supply detected as faulty by the fault detection module failure. In particular embodiments, the backup battery has a nominal voltage lower than the respective nominal voltages of the supply batteries. In particular embodiments, the backup battery has a nominal voltage lower than the respective nominal voltages of the supply batteries, and the electrical distribution network is configured so that the backup battery is connected to the electric motors in both normal supply mode and emergency supply mode, and so that the backup battery begins to supply an electric motor when the voltage across the supply battery supplying said electric motor becomes lower than the voltage across the backup battery. In particular embodiments, the backup battery is connected to each electric motor in parallel with at least one power supply battery. In specific embodiments, the electric propulsion system includes a fault detection module configured to detect the switch from normal power mode to backup power mode. In particular embodiments, the electrical distribution network includes switching means adapted to connect / disconnect the power supply batteries to the electric motors, and said electric propulsion system includes a control module configured to control the switching means for: In normal power mode: connect the power supply batteries to electric motors, In backup power mode: disconnect each battery power supply detected as faulty by the fault detection module failure. In specific embodiments, the fault detection module is configured to issue a notification to an aerial vehicle user when the electric motors are powered in emergency power mode. The user may be a passenger on the aerial vehicle or on the ground, for example, in the case of a non-passenger aerial vehicle (UAV) and / or one that is remotely piloted. According to a second aspect, this disclosure relates to an aerial vehicle incorporating an electric propulsion system according to any of the embodiments of this disclosure. The aerial vehicle may be exclusively electric-powered or hybrid-powered. Presentation of the figures The invention will be better understood upon reading the following description, given by way of non-limiting example, and made with reference to the figures which represent: [Fig.1][Fig.1]: already described, a schematic representation of an electric propulsion system according to the prior art, [Fig.2][Fig.2]: a schematic representation of a first example of the implementation of an electric propulsion system, [Fig.3][Fig.3]: a schematic representation of a second example of the implementation of an electric propulsion system, [Fig.4][Fig.4]: a schematic representation of a third example of the realization of an electric propulsion system. In these figures, identical references from one figure to another designate identical or analogous elements. For clarity, the elements shown are not to scale unless otherwise indicated. Description of the implementation methods As indicated above, this disclosure relates to an electric propulsion system for an aerial vehicle (not shown in the figures). The aerial vehicle may be purely electric or hybrid-powered. Furthermore, the aerial vehicle may be unmanned or passenger-carrying. Figure 2 schematically represents an example of the implementation of an electric propulsion system 20 according to the present disclosure. As illustrated in [Fig. 2], the electric propulsion system 20 comprises, firstly, a set of electric motors 21 for propelling the aircraft and performing the takeoff, flight, and landing phases of said aircraft. Each of said electric motors 21 can be of any type suitable for the propulsion of an aircraft. In the non-limiting example illustrated in [Fig. 2], the electric propulsion system 20 comprises eight (8) electric motors 21. More generally, the electric propulsion system 20 comprises at least two electric motors 21, the total number of electric motors 21 being able to vary from one embodiment of the electric propulsion system 20 to another. In this disclosure, the electric motors are collectively referred to (without distinction between them) by reference numeral 21, while they are individually referred to by reference numerals 21-1 to 21-8, respectively. The electric propulsion system 20 also includes a set of power batteries 22 to supply electrical energy to said electric motors 21. In the non-limiting example illustrated in [Fig. 2], the electric propulsion system 20 includes four (4) power batteries 22. More generally, the electric propulsion system 20 includes at least two power batteries 22, the total number of power batteries 22 being able to vary from one embodiment of the electric propulsion system 20 to another. In this disclosure, the power batteries are collectively referred to (without distinction between them) by reference numeral 22, while individually they are referred to by reference numerals 22-1 to 22-4, respectively. The electric propulsion system 20 also includes an electrical distribution network connecting the power batteries 22 to the electric motors 21. The electrical distribution network consists of all the elements enabling the connection of each power battery 22 to each electric motor 21 that is to be powered by that power battery 22. For example, the electrical distribution network consists of a set of power lines and discrete components. In the non-limiting example illustrated in [Fig. 2], the electrical distribution network includes, in particular, a main line 23, power lines 24-1 to 24-8 connecting the main line 23 to the various electric motors 21-1 to 21-8, and switching means (for example contactors) allowing the reconfiguration of said electrical distribution network, which will be discussed below. As illustrated in [Fig. 2], the electric propulsion system 20 also includes an additional power supply battery, referred to as the backup battery 25, adapted to be connected to each of the electric motors 21 via the electrical distribution network. It should be noted that the propulsion system 20 may also, according to other embodiments, include several backup batteries 25, for example, for the purpose of redundancy of the backup battery 25. In such cases, the backup batteries 25 are adapted to be connected to the electric motors 21 via the electrical distribution network, so that each electric motor 21 can be powered by at least one of the backup batteries 25. However, in preferred embodiments of the electric propulsion system 20, said electric propulsion system 20 includes only one backup battery 25, in order to limit the mass carried by the aircraft. In the following description, we consider the case where the electric propulsion system 20 includes a single backup battery 25, which therefore corresponds to preferred embodiments of the electric propulsion system 20 allowing to limit the margin of electrical energy and the mass carried in the aerial vehicle. In the example illustrated in [Fig. 2], the electrical distribution network also includes a charging port 26, connected to the main line 23, intended to be connected to a ground power unit (GPU) to charge the power supply batteries 22 and the backup battery 25 when the aircraft is on the ground. The electrical distribution network also includes switching means which comprise: CL1 to CLA line contactors allowing connection / disconnection each power supply battery 22-1 to 22-4 of the main line 23, a CL-S line contactor for connecting / disconnecting the battery backup line 25 of the main line 23, a CL6 line contactor allowing connection / disconnection of the port charge 26 of the main line 23. For example, during charging, line contactors CL1 to CL6 are closed to connect the main line 23 to the power batteries 22-1 to 22-4, the backup battery 25 and the charging port 26. When charging is complete, line contactors CL1 to CL6 are, for example, open to disconnect the main line 23 from the power batteries 22-1 to 22-4, the backup battery 25 and the charging port 26. In the example illustrated in [Fig. 2], the switching means of the distribution network- The electrical distribution system also includes motor contactors CMI, CM2, CM3, and CM4 arranged respectively on the supply lines 24-1, 24-3, 24-5, and 24-7. When motor contactors CM1, CM2, CM3, and CM4 are closed, the supply batteries 22-1, 22-2, 22-3, and 22-4 are connected to the electric motors 21-1, 21-3, 21-5, and 21-7, respectively. In the example illustrated in [Fig. 2], the switching means of the electrical distribution system also include: a CT1 transfer contactor arranged between the 24-1 and supply lines 24-2, a CT2 transfer contactor arranged between the 24-3 supply lines and 24-4, a CT3 transfer contactor arranged between the 24-5 supply lines and 24-6, a CT4 transfer contactor arranged between the 24-7 supply lines and 24-8. When motor contactors CM1 to CM4 and transfer contactors CT1 to CT4 are closed, the supply batteries 22-1, 22-2, 22-3 and 22-4 are also connected to electric motors 21-2, 21-4, 21-6 and 21-8, respectively. In the example illustrated in [Fig. 2], the electrical distribution network also includes diodes D1, D2, D3, and D4 arranged on the supply lines 24-2, 24-4, 24-6, and 24-8, respectively. Diodes D1 through D4 allow the passage of electric current only from the main line 23 to the electric motors 21-2, 21-4, 21-6, and 21-8. The electric propulsion system 20 may also include a control module (not shown in the figures) that controls, in particular, the line contactors CLI to CL6, the motor contactors CM1 to CM4, and the transfer contactors CTI to CT4. The control module may include, for example, one or more processors and one or more electronic memories (any type of computer-readable storage medium) in which a computer program product is stored, in the form of a set of program code instructions to be executed to control the various switching means of the electrical distribution network. Alternatively or in addition, the control module may include one or more programmable logic circuits, such as FPGAs, PLDs, etc., eVs, or specialized integrated circuits (ASICs), and / or discrete electronic components adapted to control the various switching means of the electrical distribution network. As indicated above, the electric propulsion system 20 is configured to power the electric motors 21 according to at least two different power supply modes: a so-called normal power supply mode, in which the backup battery 25 does not power any of the 21 electric motors, the electric motors being powered solely by the 22 power supply batteries, a so-called backup power supply mode, in which the backup battery 25 powers at least one electric motor. Thus, the backup battery 25 is not used in normal power mode, which is the default during takeoff, flight, and landing phases of the aircraft. However, the backup battery 25 is used in emergency power mode to take over from one or more failing power batteries 22 (due to a malfunction of power battery 22 or a low charge level). For example, in normal power supply mode, motor contactors CMI to CM4 and transfer contactors CT1 to CT4 are closed by the control module, while line contactors CLI to CL6 are opened by the control module. Thus, backup battery 25 is not connected to any of the electric motors 21-1 to 21-4. Power supply battery 22-1 powers electric motors 21-1 and 21-2, power supply battery 22-2 powers electric motors 21-3 and 21-4, power supply battery 22-3 powers electric motors 21-5 and 21-6, and power supply battery 22-4 powers electric motors 21-7 and 21-8. In emergency power mode, the control module can switch the CLS line contactor to the closed state, so that the backup battery 25 is connected to all the electric motors 21-1 to 21-8, via the power lines 24-2, 24-4, 24-6, and 24-8 respectively, and the transfer contactors CTI to CT4 are closed. The CLS line contactor thus acts as a switching device for connecting / disconnecting the backup battery 25 from the electric motors 21. To determine when to switch from normal power mode to backup power mode, the electric propulsion system 20 includes, for example, a fault detection module (not shown in the figures). The fault detection module includes, for example, a set of sensors for detecting a fault in one of the power supply batteries 22, for example, by measuring the voltages across the terminals of said power supply batteries 22. Indeed, a low charge level in a power supply battery 22 will result in a detectable drop in the voltage across its terminals, compared to the nominal voltage of said power supply battery 22. However, the fault detection module can implement any means necessary to detect a fault in a power supply battery 22. Thus, when the fault detection module detects a fault in a power supply battery 22, the control module can trigger the switch from normal power supply mode to backup power supply mode. In preferred embodiments, the control module can also isolate the backup battery detected as faulty by the fault detection module. For example, if the backup battery 22-1 has been detected as faulty, then the control module can open the motor contactor CMI to disconnect the backup battery 22-1 from the electric motors 21-1 and 21-2, which are then powered by the backup battery 25 (the transfer contactor CT1 remaining in the closed state). The motor contactors CM1 to CM4 thus correspond to switching means for connecting / disconnecting the backup batteries 22 from the electric motors 21. In the example illustrated in [Fig. 2], in the backup power supply mode, the backup battery 25 is connected to all the electric motors 21, so that it can power all the electric motors 21 even those that are still connected to non-failing backup batteries 22. In preferred embodiments, the backup battery 25 has a lower nominal voltage than the respective nominal voltages of the backup batteries 22. For example, the nominal voltage of the backup battery 25 can be between 600 Volts (V) and 700 V, and the nominal voltage of the backup batteries 22 can be between 700 V and 800 V. Therefore, in the example of [Fig. 2], the backup battery 25 is connected to all the electric motors 21, so that it can power all the electric motors 21, even those that are still connected to non-failing backup batteries 22.2] and in the backup power supply mode, an electric motor 21 will only be powered by the backup battery 25 if the voltage across the electric motor 21 (supplied by a power supply battery 22) is lower than the voltage across the backup battery 25. This will be the case for an electric motor 21 powered by a faulty power supply battery 22, but this will generally not be the case for other electric motors 21 powered by non-faulty power supply batteries 22. Therefore, in such a case, the backup battery 25, although connected to all the electric motors 21, essentially only powers the electric motors 21 powered by a faulty power supply battery 22. Furthermore, the non-faulty power supply batteries 22 do not discharge to the backup battery 25 due to the presence of diodes D1 to D4. Figure 3 schematically represents another example of an embodiment of an electric propulsion system 20 according to this disclosure. In addition to the elements already described with reference to Figure 2, the electric propulsion system 20 of Figure 3 includes motor contactors CM5, CM6, CM7 and CMB arranged on the supply lines 24-2, 24-4, 24-6 and 24-8, respectively. In the example illustrated by [Fig.3], in normal supply mode, motor contactors CM1 to CM4 and transfer contactors CT1 to CT4 are closed by the control module, while line contactors CL1 to CL6 and motor contactors CM5 to CMS8 are opened by the control module. In backup power mode, the control module closes the CLS line contactor. Preferably, the control module closes only the motor contactor, among the CMS to CMB motor contactors, that is connected to an electric motor 21 powered by the failed backup battery 22. For example, if the backup battery 22 detected as faulty is battery 22-1, then the control module closes only the CMS motor contactor. However, in other examples, it is possible to close all the CMS to CM8 motor contactors. The CLS line contactor and the CMS to CM8B motor contactors thus serve as switching means for connecting / disconnecting the backup battery 25 from the electric motors 21.As described previously, the control module can, in particular embodiments, isolate the faulty power supply battery 22 by an appropriate control of the motor contactors CM1 to CM4. Figure 4 schematically represents another embodiment of an electric propulsion system 20 according to this disclosure. The electric propulsion system 20 of Figure 4 incorporates all the elements described with reference to Figure 2, with the exception of the line contactor CLS. Thus, in this embodiment, the backup battery 25 is always connected to the electric motors 21, regardless of the power supply mode. However, in this embodiment, the backup battery 25 has a lower nominal voltage than the respective nominal voltages of the power supply batteries 22, so that the backup battery 25 does not discharge (and does not supply power to the electric motors 21) as long as the voltages across the power supply batteries 22 are higher than the voltage across the backup battery 25.However, the backup battery 25 begins to power an electric motor 21 when the voltage across the supply battery 22 that powers this electric motor 21 falls below the voltage across the backup battery 25. For example, the nominal voltage of the backup battery 25 may be between 600 Volts (V) and 700 V, and the nominal voltage of the supply batteries 22 may be between 700 V and 800 V. Thus, the backup battery 25 automatically takes over from a failing supply battery 22, without having to change the state of the various switching means of the electrical distribution network and without having to detect the failure of this supply battery 22. Consequently, the intervention of a control module or a fault detection module is not required to switch from normal power supply mode to backup power supply mode.However, the electric propulsion system 20 may nevertheless include a fault detection module configured to detect the switch from normal power mode to the mode. backup power supply. If the fault detection module is further configured to detect which power supply battery 22 is faulty, then the control module can, in particular embodiments, isolate the faulty power supply battery 22 by an appropriate control of the motor contactors CM1 to CM4. In certain embodiments, when the electric propulsion system 20 includes a fault detection module, this module is preferably configured to send a notification to an aircraft operator, informing them that the backup power mode is in use. Indeed, even though using the backup battery 25 provides a more accurate estimate of the available electrical energy, the operator must be informed that a failure of the backup battery 22 has been detected in order to trigger, for example, an emergency landing procedure. The operator is, for example, the aircraft pilot, who may be a passenger in the aircraft or on the ground, for example, in the case of a remotely piloted aircraft. More generally, it should be noted that the implementation and realization methods considered above have been described as non-limiting examples, and that other variants are therefore conceivable. In particular, the invention has been described by considering specific examples of implementation of the electric propulsion system 20. Other variants are conceivable, provided they allow for an electric propulsion system 20 comprising a backup battery 25 that is not used in a normal power supply mode for the electric motors, so that its charge level is a priori maximum and precisely known when it is used in a backup power supply mode.

Claims

Demands

1. An electric propulsion system (20) for an aerial vehicle, comprising a plurality of electric motors (21), a plurality of batteries power supply (22) to supply said electric motors with energy electrical, and an electrical distribution network linking said power supply batteries for electric motors, characterized in that said electric propulsion system (20) includes a battery additional power supply, called backup battery (25), suitable for being connected to electric motors via the distribution network electric, and in that said electric propulsion system is configured to power the electric motors according to at least two different power supply methods: a so-called normal power supply mode, in which the battery of backup (25) does not power any of the electric motors (21), said electric motors being powered by batteries power supply (22), a so-called backup power mode, in which the battery backup (25) powers at least one electric motor (21).

2. Electric propulsion system (20) according to claim 1, including a battery failure detection module power supply and a control module configured to put in operates in normal power mode when no failure of The power supply battery is not detected, and to implement the mode backup power supply in case of failure of at least one battery Power supply is detected.

3. Electric propulsion system (20) according to claim 2, in which the electricity distribution network includes the first suitable switching means for connecting / disconnecting the battery backup for electric motors, and in which the control module is configured to control the first means of switching For: In normal power mode: disconnect the battery backup for electric motors In backup power mode: connect the battery backup to at least one electric motor.

4. Electric propulsion system (20) according to claim 3, in which the electrical distribution network includes secondary means switching devices suitable for connecting / disconnecting batteries power supply to electric motors, and in which the module of The command is configured to control the second means of communication. change for: In normal power mode: connect the batteries power supply to electric motors, In backup power mode: disconnect from electric motors, each power supply battery detected as faulty by the fault detection module.

5. Electric propulsion system (20) according to claim 1, in in which the backup battery has a nominal voltage lower than respective nominal voltages of the supply batteries, and in which the electrical distribution network is configured so that the The backup battery is connected to the electric motors in mode normal power supply and in backup power supply mode, and so that the backup battery starts powering a motor electrical when the voltage across the terminals of the power supply battery which the voltage supplied to the electric motor becomes lower than that supplied terminals of the backup battery.

6. Electric propulsion system (20) according to claim 5, in to which the backup battery is connected to each electric motor in parallel to at least one power supply battery.

7. Electric propulsion system (20) according to any one of the re- sales 5 to 6, including a fault detection module configured to detect the transition from normal power mode to the backup power supply mode.

8. Electric propulsion system (20) according to claim 7, in which the electrical distribution network includes means of communication modifications adapted to connect / disconnect the power supply batteries to electric motors, said electric propulsion system including a control module configured to control the switching methods for: In normal power mode: connect the batteries power supply to electric motors, In backup power mode: disconnect from electric motors, each power supply battery detected as faulty by the fault detection module.

9. Electric propulsion system (20) according to any one of the re- claims 2 to 4, 7 and 8, in which the de- detection module faillance is configured to send a notification to a user of the aerial vehicle when the electric motors are powered according to the backup power supply mode.

10. Aerial vehicle comprising an electric propulsion system (20) according to any one of claims 1 to 9.