Architecture for parallelizing electrical sources of an electrically propelled aircraft, and associated method

Abstract

The invention relates to an electrical architecture (1) for supplying power to an electrical propulsion system (3) of an aircraft (5) comprising two engines (7), the electrical architecture comprising two electrical sources (9) each intended to supply power to one of the engines (7), a flight control computer (11), and two electrical buses (13) each intended to connect an electrical source (9) to a respective engine (7), and a parallelization controller (17) for parallelizing the electrical sources (9) and a switching member (19) configured to electrically connect the two electrical buses (13) upon command of the parallelization controller (17), the parallelization controller (17) being configured to order changing of the supply of power to at least one engine (7) so as to equalize the voltages across the terminals of the switching member (19).

Description

[0001] DESCRIPTION

[0002] TITLE: Architecture for the parallelization of electrical sources of an electrically powered aircraft and associated method

[0003] Technical field

[0004] The present invention relates to the architectures of electrical distribution networks in electrically powered aircraft.

[0005] In particular, the present invention relates to the control of the paralleling of electrical sources for the power supply of the propulsion system of an aircraft.

[0006] Generally speaking, the invention applies to any electrical architecture suitable for controlling the paralleling of electrical elements.

[0007] Previous techniques

[0008] A traditional aeronautical electrical network is generally either an alternating current network, with a voltage value of 115V AC or 230V AC, associated with a low voltage direct current network of 28V DC, or a single network with a direct voltage of 28V DC.

[0009] Aircraft operating via an AC network have a total on-board electrical power ranging from 50 to 500 kW, or even 1 MW, while purely DC networks have more limited on-board powers of less than 100 kW. To date, there are practically no high-voltage DC networks, a type of network rather reserved for local networks limiting the current or voltage rating of the switching and protection devices.

[0010] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new aircraft types and those currently in operation, requiring the implementation of technological solutions to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0011] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the factors impacting all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft. Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible to reduce the environmental footprint of its activity.

[0012] This sustained research and development work focuses in particular on the development of the use of electrical technologies to provide propulsion.

[0013] In this context, new electrically powered aircraft, using batteries as their main power sources, involve powers of at least 100kW, and therefore operate at high DC voltages above 400V DC, moving away from the practices of known reference aeronautical electrical networks. For these new electrically powered aircraft, it is necessary to define new electrical distribution architectures.

[0014] Today, two distribution architecture topologies are studied: segregated architectures and distributed architectures.

[0015] As their name suggests, segregated electrical architectures supply electrical energy to the propulsion system through multiple distribution channels segregated from each other.

[0016] In other words, each channel is composed of a source of electrical energy which supplies one or more electric motors depending on the topology of the aircraft, which multiplies the number of electrical elements to be integrated into the aircraft, increases its mass, and complicates the integration of said elements.

[0017] In contrast to segregated architectures, distributed electrical architectures supply electrical energy to the propulsion system through multiple distribution channels connected to each other.

[0018] In this type of architecture, electricity sources such as batteries are connected in parallel to the high-voltage DC network. In nominal mode, the voltages between the different batteries balance each other so that the batteries share power for the different propulsion loads, such as motors. In the event of a battery loss, the propulsion loads are powered by the remaining batteries. This makes it possible to size the batteries as close as possible to the nominal operation, and thus optimize the mass of the batteries. The electricity distribution network also becomes more integrated because the distribution architecture combines several propulsion loads with several batteries.

[0019] So, it should be possible to be able to put a set of batteries in parallel, or not, depending on their voltage.

[0020] One of the difficulties of this type of architecture is the management of battery parallelization, which can induce very high currents that can be damaging or can cause a malfunction of the electrical network if said management of battery parallelization is not mastered. Problems of overcurrent or energy transfer from one battery to another can thus occur as a result of poor management of battery parallelization.

[0021] For this, there are so-called "passive" battery parallelization devices which consist of connecting a resistor between the two batteries, while their voltage level balances, allowing them to be parallelized while limiting the current draw.

[0022] Other so-called "active" devices will actively regulate the current between the two batteries to be parallelized, while their voltage level balances, allowing them to be parallelized by limiting the current draw. These devices dissipate energy while the batteries are paralleled. They are also less suitable during battery parallelization when a propellant charge is connected to the batteries, because in this case the paralleling time could be significantly increased and will have a negative impact on the sizing of said devices.

[0023] Statement of the invention

[0024] The present invention therefore aims to overcome the aforementioned drawbacks and to provide an architecture for controlling the parallelization of electricity sources by modifying the electrical consumption of the propellant charges to which they are connected. The present invention thus makes it possible to avoid the use of a specific device for parallelizing electricity sources, in particular precharging circuits.

[0025] The present invention relates to an electrical architecture for powering an electric propulsion system of an aircraft comprising two motors, the electrical architecture comprising two electrical sources each intended to power one of the motors, a flight control computer, and two electrical buses each intended to connect an electrical source to a respective motor, the architecture comprising a controller for paralleling the electrical sources and a switching member configured to electrically connect the two electrical buses on command from the parallelization controller, the parallelization controller being configured to order the modification of the power supply to at least one motor so as to equalize the voltages at the terminals of the switching member.

[0026] This eliminates the need for a specific circuit for paralleling the electrical sources, as voltage equalization is achieved solely by changing the consumption of the electric propulsion system.

[0027] The present invention also relates to an aircraft comprising an electric propulsion system comprising two motors, as well as an electrical architecture as defined previously. The present invention also relates to a method for parallelizing electrical sources, implemented by the electrical architecture or by the aircraft as defined previously, the method comprising the following steps:

[0028] - Receipt of a request for parallelization of electrical sources by the parallelization controller;

[0029] - Measurement by the parallelization controller of the voltage difference between the terminals of the switching device;

[0030] - Calculation of a regulation law for the supply power of at least one motor by the parallelization controller as a function of the measured voltage difference, the regulation law being calculated so as, once applied, to equalize the voltages at the terminals of the switching device;

[0031] - Control of the power of at least one engine by the flight control computer according to the calculated regulation law;

[0032] - Closing of the switching device to parallelize the electrical sources as soon as the voltage difference between the terminals of the switching device is lower than a first predetermined threshold.

[0033] Advantageously, before the step of receiving the parallelization request, the flight control computer performs a step of confirming that the flight conditions of the aircraft allow parallelization.

[0034] In a particular implementation mode, after the step of receiving the parallelization request, the parallelization controller performs a step of verifying that the state of the electrical sources and the electrical architecture authorizes parallelization.

[0035] Advantageously, the parallelization controller performs a step of comparing the measured voltage difference with a second predetermined threshold and begins the step of calculating the regulation law of the supply power of at least one motor only if the measured voltage difference is lower than said second predetermined threshold.

[0036] In one embodiment, the flight control computer performs a step of comparing the calculated regulation law with the operating limits of the aircraft and / or the electric propulsion system, and begins the step of piloting at least one engine according to the calculated regulation law only if the regulation law does not exceed said operating limits.

[0037] Advantageously, the step of closing the switching member is only carried out if the voltages at the terminals of the switching member converge towards the same value in a duration less than a predetermined duration.

[0038] The method may further comprise a step of rebalancing the powers of the two motors after the implementation of the step of closing the switching member.

[0039] Advantageously, the two electrical sources are electric batteries and the method comprises a step of reopening the switching member implemented after the step of closing the switching member if, beyond a predetermined time, the two electrical sources are not in an identical state or in a state provided beforehand, the two electrical sources are not in an identical state of recharging or discharging.

[0040] Brief description of the drawings

[0041] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0042] [Fig 1] is a schematic view of an electrical architecture according to an exemplary embodiment of the invention for the parallelization of electrical sources of an electric propulsion system 3 of an aircraft;

[0043] [Fig 2] is a schematic timing diagram of a parallelization representing the value of the voltages VI, V2, the currents II, I2 and the powers PI and P2 of the supply of two motors as a function of time t, according to a first mode of implementation; [Fig 3] is a schematic timing diagram of a parallelization representing the value of the voltages VI, V2, the currents II, I2 and the powers PI and P2 of the supply of two motors as a function of time t, according to a second mode of implementation; and

[0044] [Fig 4] is a schematic representation of the steps of a method for parallelizing electrical sources according to an exemplary embodiment of the invention.

[0045] Detailed description of at least one embodiment

[0046] Figure 1 schematically shows an electrical architecture 1 for powering an electric propulsion system 3 of an aircraft 5.

[0047] As illustrated, the electric propulsion system 5 comprises two electric motors 7, the electrical architecture 1 comprising two electrical sources 9 each intended to power one of the motors 7. Such a representation makes it possible to simplify the present description but a greater number of electrical sources 9 and / or motors 7 may be present in the aircraft 5.

[0048] Preferably, the aircraft 5 comprises as many electrical sources 9 as motors 7, without this being an obligation, the electrical sources 9 or the motors 7 being able to be present in excess of the other.

[0049] The electrical sources 9 are preferably electric batteries, but can also be other types of sources such as generators, for example synchronous magnet generators associated with passive rectifiers.

[0050] In this embodiment, the electrical architecture 1 comprises a flight control computer 11, as well as two electrical buses 13 each intended to connect an electrical source 9 to a motor 7. The electrical buses 13 are preferably high-voltage direct current electrical buses. In this embodiment, voltages greater than 400 Volts DC are considered. The flight control computer 11 controls the motors 7 by sending them performance and / or power supply instructions via a communication channel 15. The motors 7 communicate their status and their operating characteristics to the flight control computer 11 also via the communication channel 15.

[0051] The electrical architecture 1 further comprises a parallelization controller 17 of the electrical sources 9 and a switching member 19 configured to electrically connect the two electrical buses 13 on command from the parallelization controller 17.

[0052] Thus, when the switching member 19 is closed, the electrical architecture 1 is said to be distributed and the two electrical sources 9 are arranged in parallel and supply the two motors 7. Conversely, when the switching member 19 is open, the electrical architecture 1 is segregated and each electrical source 9 is electrically connected to only one motor 7.

[0053] The role of the parallelization controller 17 is to allow the present electrical architecture 1 to move from a segregated architecture, generally the initial type of architecture when starting the aircraft 5, to a distributed architecture.

[0054] Thus, when the conditions are met and the flight control computer 11 sends a request 21 for parallelization of the electrical sources 9 to the parallelization controller 17, the latter is configured to send in return to the flight control computer 11 a piloting instruction 23 for at least one motor 7. For example, the flight control computer 11 can then send to a motor 7 an instruction for modifying the power supply of said motor 7, so that the power supply current of said motor 7 is modified so as to equalize the voltages V1 and V2 at the terminals of the switching member 19.

[0055] Indeed, in order to connect the electrical sources 9 in parallel, it is necessary that the voltage difference |V 1 -V2| between the terminals of the switching member 19 is less than a first predetermined threshold, for example set between 1 and 5 Volts. The parameters that can influence the voltages at the terminals of the switching member 19 are the currents II and I2 passing through the electrical buses 13 and the powers PI and P2 of the respective supply of the motors 7, such as:

[0056] P l = VI. I l = (Vs l - Rb l .11). He ; And

[0057] P2 = V2.I2 = (Vs2 - Rb2.I2).I2, with Vs l and Vs2 the output voltages of the electrical sources 9 and Rb l and Rb2 the resistances of the electrical buses 13, the harnesses and the components potentially positioned between each electrical source 9 and the switching device 19.

[0058] Figure 2 shows a timing diagram of a parallelization schematically representing the value of the voltages VI, V2, the currents II, I2 and the powers PI and P2 as a function of time t.

[0059] During an initial phase 27, the electrical architecture 1 is segregated: the motors 7 operate at the same power P 1 =P2 but the voltages VI and V2 are not equal, due to different initial conditions. Once the flight control computer 1 1 has the instruction to initiate parallelization, it sends to a motor 7 a control instruction 23, in other words a modification of the power P2 of said motor 7, this instruction being equivalent to an instruction to modify the intensity 12. As illustrated, V2 being initially less than VI , 12 and P2 decrease during the parallelization phase 29, until the voltage difference | VI -V2| between the terminals of the switching member 19 is less than the first predetermined threshold.

[0060] The voltages VI and V2 being thus equalized, the parallelization controller 17 can send a closing instruction 25 to the switching device in order to make the electrical architecture 1 distributed.

[0061] Subsequently, during the post-parallelization phase 3 1 , it is possible for the flight control computer 1 1 to send instructions 33 to the engine in order to obtain a rebalancing 35 of the powers of the engines 7 at the same level P 1 =P2. As an alternative to the timing diagram presented in FIG. 2, it is also possible to increase the power and intensity of an engine 7 in order to lower the associated voltage.

[0062] In another variant illustrated in Figure 3, the powers and intensities of the two motors 7 can be modified at the same time following an instruction 23 from the flight control computer 11. This variant is particularly advantageous since it is on average faster, requiring only a few seconds, and makes it possible to avoid any loss of overall power within the electric propulsion system 3 of the aircraft 5.

[0063] In a particular embodiment in which the electrical architecture 1 comprises more than two electrical sources 9, the parallelization is carried out two by two, or by group of electrical sources 9 already parallelized with each other, or even by parallelization of one electrical source 9 at a time with a group of electrical sources 9 already parallelized.

[0064] In order to describe in more detail the electrical parallelization method according to the invention, the steps of said method are shown schematically in the flowchart illustrated in Figure 4.

[0065] The method is generally implemented for the transition to a specific flight mode of the aircraft 5 in which it is advantageous to have a distributed rather than segregated electrical architecture 1. The electrical architecture 1 is generally in its segregated configuration when the aircraft starts, for example due to a different charge between two batteries acting as electrical sources 9.

[0066] Thus, following a manual command from the pilot of the aircraft 5, or following an automatic process of switching to a particular flight mode, a step 37 of requesting parallelization of the electrical sources 9 is carried out by the flight control computer 11.

[0067] Then, the flight control computer 11 performs a step 39 of confirmation that the flight conditions of the aircraft allow parallelization. This step 39 makes it possible, for example, to confirm that the altitude and / or the speed of the aircraft can be slightly reduced while parallelization is carried out, the duration being less than ten seconds in general. These data are to be put into perspective with the thrust limits of the engines 7.

[0068] Then, the parallelization request 21 of the electrical sources 9 is transmitted to the parallelization controller 17 which receives this request during step 41.

[0069] The parallelization controller 17 then performs a step 43 of verifying that the state of the electrical sources 9 and of the electrical architecture 1 authorizes parallelization.

[0070] The electrical sources 9 communicate directly with the parallelization controller 17. If faults or failures are identified, or if over-temperature or over-current is measured, then the parallelization of the electrical sources 9 is aborted, according to the status 45 illustrated. Similarly, if the electrical sources 9 are batteries, it is verified that their charge range is within a predetermined range that is neither discharging nor overcharging, and the charge difference between the two batteries must be less than a predetermined limited threshold.

[0071] Once this verification step 43 has been carried out, the parallelization controller 17 carries out a step 47 of measuring the voltage difference |V 1 -V2| between the terminals of the switching member 19.

[0072] The parallelization controller 17 performs a step 49 of comparing the voltage difference |V 1 -V2| measured with a first predetermined threshold, for example 5 Volts, and with a second predetermined threshold, for example between 50 and 75 Volts.

[0073] Obviously, if the measured voltage difference |V 1 -V2| is lower than the first predetermined threshold, the parallelization controller 17 orders the implementation of a step 51 of closing the switching member.

[0074] On the other hand, if the measured voltage difference |V 1 -V2| is greater than the second predetermined threshold, then the parallelization of the electrical sources 9 is considered impossible and abandoned, according to the status 45 illustrated. Finally, if the measured voltage difference |V 1 -V2| is between the first predetermined threshold and the second predetermined threshold, the parallelization controller 17 performs a step 53 of calculating a regulation law for the supply power of at least one of the motors 7 as a function of said measured voltage difference |V 1 -V2|, the regulation law being calculated so as, once applied to the motor(s) 7, to equalize the voltages V1 and V2 at the terminals of the switching member 19.

[0075] The calculation of the regulation law is done from predictive models and includes parameters of the control strategy of the motors 7. The predictive models take into account the impedances of the electrical architecture 1, the state of the electrical sources as well as that of the motors 7.

[0076] After the parallelization controller 17 has communicated the calculated regulation law to the flight control computer 11, said flight control computer 11 performs a step 55 of comparing the calculated regulation law with the operating limits of the aircraft 5 and / or the electric propulsion system 3 in order to verify whether the regulation law does not exceed said operating limits if it were implemented. If necessary, the parallelization of the electrical sources 9 is considered impossible and abandoned, according to the status 45 illustrated.

[0077] If the operating limits appear to be respected, the flight control computer 11 performs a step 57 of controlling the power of at least one engine 7 by the flight control computer 11 according to the calculated regulation law. The control instructions 23 sent make it possible in particular to modify the intensity and the power of the supply current of said engine 7 in order to attempt to make the voltages VI and V2 converge towards the same value. On the other hand, a test step 59 is carried out to ensure that the voltages VI and V2 at the terminals of the switching member 19 converge towards the same value in a duration less than a predetermined duration, for example 10 seconds. If this is not the case, the parallelization of the electrical sources 9 is considered impossible and abandoned, according to the status 45 illustrated.

[0078] On the other hand, if the measured voltage difference | VI -V2| becomes lower than the first predetermined threshold, the parallelization controller 17 orders, via a closing instruction 25, the implementation of a step 51 of closing the switching member 19 to parallelize the electrical sources 9.

[0079] Generally speaking, the closing of the switching member 19 implies a natural convergence of the voltages VI and V2 and other electrical characteristics of the electrical architecture 1.

[0080] A final step 61 can still be carried out to verify that, beyond a predetermined time, the two electrical sources 9 are in an identical state or in a previously planned state. If this is not the case, a step 63 is carried out to reopen the switching member 19 in order to segregate the electrical architecture 1 again and abandon the parallelization, according to the status 45 illustrated.

[0081] For example, if the electrical sources are batteries, after the switching member 19 has closed, one may be in a discharged state while the other is recharging. However, this state is only permitted for a predefined duration and with a search current below a pre-established threshold.

[0082] Optionally, and if parallelization has not been abandoned, the method further comprises a step 65 of rebalancing 35 the powers of the two engines 7 after the implementation of the step 61 of closing the switching member 19, so as to obtain a uniform thrust of the engines 7, corresponding to the initial thrust for example. The instructions 33 of this rebalancing are sent by the flight control computer 11.

[0083] Finally, parallelization is considered effective according to status 67.

Claims

CLAIMS 1. Method for parallelizing electrical sources (9), implemented by an electrical architecture (1) for powering an electric propulsion system (3) of an aircraft (5) comprising two motors (7), the electrical architecture (1) comprising two electrical sources (9) each intended to power one of the motors (7), a flight control computer (11), two electrical buses (13) each intended to connect an electrical source (9) to a respective motor (7), a parallelization controller (17) of the electrical sources (9) and a switching member (19) configured to electrically connect the two electrical buses (13) on command of the parallelization controller (17), the parallelization controller (17) being configured to order the modification of the power supply of at least one motor (7) so as to equalize the voltages at the terminals of the switching member (19), characterized in that it comprises the following steps: : Reception (step 41) of a parallelization request (21) of the electrical sources (9) by the parallelization controller (17); Measurement (step 47) by the parallelization controller (17) of the voltage difference between the terminals of the switching member (19); Calculation (step 53) of a regulation law for the supply power of at least one motor (7) by the parallelization controller (17) as a function of the measured voltage difference, the regulation law being calculated so as, once applied, to equalize the voltages at the terminals of the switching member (19); Controlling (step 57) the power of at least one engine (7) by the flight control computer (11) according to the calculated regulation law; Closing (step 51) of the switching member (19) to parallelize the electrical sources (9) as soon as the difference voltage between the terminals of the switching member (19) is lower than a first predetermined threshold.

2. Method according to claim 1, in which, before the step (41) of receiving the parallelization request (21), the flight control computer (11) carries out a step (39) of confirming that the flight conditions of the aircraft (5) allow parallelization.

3. Method according to one of claims 1 and 2, in which, after the step (41) of receiving the parallelization request, the parallelization controller (17) performs a step (43) of verifying that the state of the electrical sources (9) and of the electrical architecture (1) authorizes parallelization.

4. Method according to any one of claims 1 to 3, in which the parallelization controller (17) performs a step (49) of comparing the measured voltage difference with a second predetermined threshold and begins the step (53) of calculating the regulation law of the supply power of at least one motor (7) only if the measured voltage difference is lower than said second predetermined threshold.

5. Method according to any one of claims 1 to 4, in which the flight control computer (11) performs a step of comparing the calculated regulation law with the operating limits of the aircraft (5) and / or the electric propulsion system (3), and begins the step (57) of piloting at least one engine (7) according to the calculated regulation law only if the regulation law does not exceed said operating limits.

6. Method according to any one of claims 1 to 5, in which the step (51) of closing the switching member (19) is only carried out if the voltages at the terminals of the switching member (19) converge towards the same value in a duration less than a predetermined duration.

7. Method according to any one of claims 1 to 6, further comprising a step (65) of rebalancing the powers of the two motors (7) after the implementation of the step (51) of closing the switching member (19).

8. Method according to any one of claims 1 to 7, in which the two electrical sources (9) are electric batteries, the method comprising a step (63) of reopening the switching member (19) implemented after the step (51) of closing the switching member (19) if, beyond a predetermined time, the two electrical sources (9) are not in an identical state of recharging or discharging.

9. Aircraft (5) comprising an electric propulsion system (3) comprising two motors (7), characterized in that it comprises an electrical architecture (1) implementing the method according to any one of claims 1 to 8.

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