Method for determining at least one power limit of a hybrid drive system of a transport vehicle, in particular an aircraft

Abstract

The invention relates to a method for determining at least one minimum power margin of a hybrid drive system for a transport vehicle, each drive element being associated with at least one power source and at least one power consumer, the method comprising the following steps: a step of acquiring (ET1) measured values ​​(Pv) of a power parameter (PARi); a step of comparing (ET2) each measured value (Pv) with at least one limiting threshold value in order to derive therefrom at least one overall margin (Pmb); a step of converting (ET3) the overall margin (Pmb) into a fine margin (Pma) expressed according to the same common magnitude; a step of converting (ET4) the fine margin (Pma) into a normalized margin (Pmn) at at least one reference point; a step of determining (ET5) a source power margin (MIndS) and a consumer power margin (MIndC) at said reference point and a step of determining (ET6) a minimum power margin (MInd) by selecting the lowest power margin.

Description

Technical Field

[0001] The present invention relates to the field of hybrid propulsion systems for transport vehicles, in particular aircraft. In a known manner, proposals have been made to equip aircraft with hybrid propulsion systems comprising several different power sources to drive multiple drive elements, in particular at least one turbine and at least one battery. Such hybrid propulsion systems enable aircraft to optimally transport goods and merchandise while limiting noise pollution and fuel consumption, and improving safety. Background Art

[0002] As an example, with reference to FIG1 , an aircraft 1 is schematically shown that includes a hybrid drive system 2 comprising four drive elements H1-H4, in particular propellers. Each drive element H1-H4 is connected to two electric motors to enable propulsion: a primary electric motor M1A-M4A and a secondary electric motor M1B-M4B. As shown in FIG1 , the primary electric motors M1A-M4A are electrically connected to a primary battery BATA via a primary channel CA, while the secondary electric motors M1B-M4B are electrically connected to a secondary battery BATB via a secondary channel CB. The hybrid drive system 2 comprises a turbogenerator TG, which includes a gas turbine and supplies power to the electric motors M1A-M4A, M1B-M4B and the batteries BAT, BATB via channels CA, CB. In this example, the drive is referred to as a series hybrid.

[0003] In a known manner, the hybrid drive system 2 can adopt different architectures, in particular:

[0004] A series architecture where the gas turbine produces only electrical energy (turbogenerator) to power the channel and charge the battery.

[0005] A parallel architecture in which the gas turbine generates only mechanical power to drive the drive elements. Electricity is provided by batteries, which are charged by the electric motor, which then acts as both a motor and an electrical generator.

[0006] A series and parallel architecture in which the power generated by the gas turbine is used both mechanically to drive the drive elements and electrically to power the electric motors or charge the batteries. This architecture combines the functionality of a series hybrid and a parallel hybrid.

[0007] Every hybrid drive system has a power limit, which depends on many parameters, in particular its architecture, the maximum torque of the gas turbine, the maximum AC current of the turbogenerator, the maximum current supplied to the channels during power generation, the maximum current that the battery can provide, the maximum current that the drive motor can operate at, etc. In other words, it is difficult to determine the power limit of a hybrid drive system.

[0008] In addition, the hybrid drive system 2 is designed to operate in a variety of configurations to compensate for failures of certain energy sources. For example, the hybrid drive system can operate under the following conditions:

[0009] Nominal construction with all available sources capable of providing part of the power requirements.

[0010] The construction on the batteries BATA and BATB is performed only in the event of a failure of the turbine generator TG.

[0011] The structure on the turbine generator TG is to prevent the failure of the batteries BATA and BATB.

[0012] In any aircraft, the power supply required by the pilot (manual or automatic) is crucial for flight safety, as it is responsible for providing levitation. This critical nature is further emphasized in VTOL aircraft (vertical take-off / landing vehicles), as the power generated by each actuating element not only contributes to levitation but also helps control the aircraft's attitude, thus directly contributing to flight stability.

[0013] In some cases, adhering to these power requirements may conflict with certain performance limitations of the drive system. When this happens, the drive system may no longer be able to meet the demand and may protect itself by continuing to provide service but limiting the power delivered, or by following the power demand until a protective device is triggered, which may result in a partial or complete power outage.

[0014] Regardless of the behavior of the propulsion system, the pilot may be "surprised" by the refusal (or loss) of power supply. This can be detrimental if the latter is performing "complex" or critical operations. In fact, the latter may find it difficult to compensate for the lack of power, which will have consequences that affect flight safety.

[0015] To eliminate this drawback, the straightforward solution consists in increasing the power capacity of the drive system in order to have a larger safety margin under all operating conditions and in all configurations. This solution cannot be retained because it would affect the mass of the drive system and thus reduce the mass that can be boarded by the aircraft.

[0016] One of the purposes of the invention is to enable a pilot (human or automatic) to permanently determine the available power margin of the hybrid drive system, so as to be able to determine the control commands that can be executed while ensuring the safety of the aircraft flight.

[0017] Several methods for determining the power margin are known in the prior art from patents US Pat. No. 6,411,869 B2, EP Pat. No. 3,647,192 A1 and EP Pat. No. 3,095,695 A1. Summary of the Invention

[0018] The invention relates to a method for determining at least one minimum power margin of a hybrid drive system for a transport vehicle, in particular an aircraft, the drive system comprising a plurality of power sources, a plurality of power consumers, and a plurality of drive elements, each drive element being associated with at least one power source and at least one power consumer, the method comprising:

[0019] Acquisition step: acquiring measurement values ​​of a plurality of power parameters of the hybrid drive system, and representing at least two measurement values ​​according to different magnitudes;

[0020] Comparison step: a step of comparing each measured value with at least one limiting threshold value, determined separately for each power parameter in the threshold value database, in order to deduce therefrom at least one total power margin for said power parameter;

[0021] A conversion step: converting the total power margin of the power parameter into a fine power margin expressed according to the same common magnitude from a conversion database;

[0022] a permutation step of converting the refined power margin to a normalized power margin at at least one reference point from a yield database that determines the yield at an interface between an acquisition point and a reference point;

[0023] Determining step: a step of determining a source power margin based on a normalized power margin of a source at the reference point, and determining a consumer power margin based on a normalized power margin of a consumer at the reference point.

[0024] Determining step: determining a minimum power margin by selecting the lowest power margin between the consumer power margin and the source power margin at the reference point.

[0025] In the absence of "visibility" into the available power margin, the control system (manual or automatic) may be required to overstress a portion of the drive system elements. Thanks to this invention, knowing the available margin at all times enables the control system to plan feasible operations while staying within the available power range.

[0026] By hybrid it is understood that the drive system comprises a plurality of different types of power sources, such as at least one heat source (thermal turbine or other) and at least one electric power source (battery, hydrogen fuel cell or other).

[0027] A reference point is a physical point in a drive system.

[0028] The power consumer is designed to consume power, for example a motor, in particular an electric motor. The power consumer is designed to supply power to a drive element, in particular a rotationally driven pulley. The power consumer is, for example, an electric motor that drives the drive element.

[0029] As mentioned above, the calculation of the instantaneous power margin is particularly complex for hybrid drive systems with numerous heterogeneous physical quantities (mechanical torque and speed, alternating current, direct current and voltage, etc.) and various technologies whose limitations depend on independent factors (atmospheric pressure and temperature for the internal combustion engine, charge level and temperature of the battery, voltage level of the electrical equipment). Thanks to the steps according to the invention, the different power parameters are processed in an orderly manner so that they are evaluated at the same reference point in order to obtain the relevant minimum power margin.

[0030] Preferably, the source power margin is obtained by a weighted sum of the normalized power margins of the sources at said reference point. Preferably, the weighting factors may take into account the overall architecture (power distribution and distribution of the latter to consumers).

[0031] Preferably, the power margin of the consumer is obtained by a weighted sum of the normalized power margins of the consumers at said reference point. Preferably, the weighting factors may take into account the overall architecture (power distribution and distribution of the latter to the consumers).

[0032] Preferably, the reference point corresponds to one or more drive elements. This is particularly important for control systems that want to understand the available power at the drive element level (the power available to move the aircraft). Therefore, it is necessary to consider the energy yields of the various drive elements. These yields may also vary depending on the operating conditions of the system (e.g., depending on the power level, the temperature of the electrical equipment, etc.).

[0033] Preferably, when the power source supplies a plurality of power consumers in parallel, it is assumed that the total power received in the node is evenly distributed among the power consumers.

[0034] Alternatively, when the power source supplies multiple power consumers in parallel, the total power received in a node is distributed weightedly between the power consumers, preferably according to the nominal power of each power consumer. This distribution is relevant when the nominal powers of the consumers are very different.

[0035] Preferably, for an aircraft, the power margins are grouped according to the main axes of the aircraft to indicate the margins for roll, pitch, and yaw.

[0036] According to a preferred technical solution, the drive system includes at least one turbine generator and at least one battery as power sources.

[0037] According to a preferred embodiment, the drive system has a plurality of electric motors as power consumers.

[0038] The present invention also relates to a method for controlling a transport vehicle, in particular an aircraft, comprising a hybrid drive system by means of a control system, the method comprising:

[0039] The step of determining, by a control system, a control command for a transport vehicle, in particular an aircraft, the control command being linked to a power requirement,

[0040] The step of determining at least one minimum power margin of the drive system by the aforementioned method, and

[0041] The step of validating the control commands when the power demand is below a minimum power margin.

[0042] Thanks to the control method used, control commands are dynamically verified before implementation, thus avoiding overloading the drive system.

[0043] The invention further relates to a hybrid drive system for a transport vehicle, in particular an aircraft, comprising a plurality of power sources, a plurality of power consumers, and a plurality of drive elements, each drive element being associated with at least one power source and at least one power consumer, the drive system comprising at least one computer, the at least one computer being configured to:

[0044] Obtaining measurements of a plurality of power parameters of the hybrid drive system, representing at least two of the measurements according to different magnitudes;

[0045] comparing each measured value with at least one limiting threshold value, which is determined for each power parameter in the threshold value database, in order to deduce at least one total power margin for said power parameter;

[0046] The total power margin of the power parameter is converted from a conversion database into a fine power margin expressed according to the same common magnitude.

[0047] converting a refined power margin from a yield database determining a yield of a transmission component between an acquisition point and a reference point into a normalized power margin at at least one reference point,

[0048] A source power margin is determined based on the normalized power margin of the source of the reference point, and a consumer power margin is determined based on the normalized power margin of the consumer of the reference point.

[0049] The minimum power margin is determined by selecting the lowest power margin between the consumer power margin and the source power margin at the reference point.

[0050] The conversion database and the yield database are accessible by the computer and are preferably stored in the computer.

[0051] The invention also relates to a transport vehicle, in particular an aircraft, comprising at least one hybrid drive system as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The invention will be better understood on reading the following description, given by way of example, and by reference to the following figures, given by way of non-limiting example, wherein the same references are given to similar matters.

[0053] FIG. 1 is a schematic diagram of the top of a drive system of an aircraft.

[0054] FIG2 is a detailed schematic diagram of the aircraft's drive system.

[0055] FIG3 is a schematic diagram of method steps for determining a power limit of an aircraft hybrid propulsion system.

[0056] FIG4 is a schematic diagram of an example of an acquisition step.

[0057] FIG5 is a schematic diagram of the steps for determining the overall margin.

[0058] FIG6 is a schematic diagram of determining the power margin based on the normalized power margin of the first driving element, and

[0059] FIG. 7 is a schematic diagram of a control method using individual power margins.

[0060] It should be pointed out that the drawings illustrate the invention in detail in order to implement it, and that said drawings can of course be used to better define the invention if necessary. DETAILED DESCRIPTION

[0061] The present invention relates to a method for determining a power limit for a hybrid drive system for a transport vehicle, in particular an aircraft. Preferably, with reference to FIG1 , a hybrid drive system 2 (hereinafter referred to as "drive system 2") comprises a plurality of different types of power sources (hybrid power system). Preferably, the present invention is applied to a distributed drive system 2, i.e., one comprising a plurality of power consumers (distributed system).

[0062] As previously mentioned, hybrid drive systems can have various architectures. For example, referring to FIG1 , a series hybrid drive system 2 is presented, comprising four drive elements H1-H4, in particular propellers. Each drive element H1-H4 is associated with at least one power source and at least one power consumer.

[0063] In this example, each H1-H4 drive element is connected to two electric motors to enable drive: a primary motor M1A-M4A and a secondary motor M1B-M4B. The primary motors M1A-M4A are electrically connected to a primary battery BATA via a primary channel CA, while the secondary motors M1B-M4B are electrically connected to a secondary battery BATB via a secondary channel CB. Drive system 2 includes a turbine generator TG, which supplies power to the motors M1A-M4A, M1B-M4B and batteries BAT and BATB via channels CA and CB. While a turbine generator TG and a battery are described, the present invention is applicable to any power source, particularly a fuel cell or electrical energy storage device (supercapacitor, electrochemical cell, etc.).

[0064] With reference to FIG2 , the drive system 2 of FIG1 is shown in more detail. The turbine generator TG comprises a gas turbine TAG which drives two electrical generators GENA and GENB (a primary electrical generator GENA and a secondary electrical generator GENB). In this example, the turbine TAG comprises a low-pressure shaft and a high-pressure shaft known to those skilled in the art. In a known manner, in this example, the turbine generator TG generates continuous electrical power from the combustion of fuel. Each electrical generator GENA and GENB converts this mechanical power into an alternating voltage and current Iac. TGA , Iac TGB The turbine generator TG also includes two rectifiers REDA and REDB to provide direct voltage and current Idc for the main channel CA and the secondary channel CB. TGA 、Idc TGB .

[0065] Channels CA and CB are also powered by two batteries BATA and BATB, each battery provides a DC Idc BATA 、Idc BATB Preferably, each battery BATA, BATB is equipped with a control and monitoring system (BMS) which determines the maximum current Idcmax it can provide at any time BATA 、Idcmax BATB (Figure 2). Therefore, this maximum current varies over time and according to operating conditions. The two channels CA and CB are independent, each containing nodes that combine the currents from the batteries BATA and BATB and the turbine generator TG to distribute power to at least two motors, or in this example, eight motors M1A-M4A and M1B-M4B.

[0066] Still referring to Figure 2, the main channel CA provides four motors M1A-M4A through four inverters ONDIA-OND4A, which convert the direct power into AC voltage and current Iac M1A -lac M4ALikewise, the secondary channel CB supplies four motors M1B-M4B via four inverters OND1B-OND4B, which convert the direct power into AC voltage and current Iac M1B -Iac M4B Thus, each drive element H1-H4 is driven by two motors M1A / M1B-M4A / M4B, which rotate at a speed proportional to the drive element H1-H4, and each motor provides a mechanical torque. The drive torque of each drive element H1-H4 is the sum of the torques provided by each of the two coupled motors M1A / M1B-M4A / M4B.

[0067] 2 , the drive system 2 includes an engine calculator CAL that controls the components of the drive system 2 and obtains their power parameters to calculate power margins. The engine calculator CAL is connected to one or more aircraft computers to enable communication with the aircraft's control system.

[0068] In a known manner, the drive system 2 comprises a plurality of power parameters PARi, which identify said drive system 2. The power parameters PARi are, for example:

[0069] Speed ​​N1 of the high-pressure shaft of the gas turbine TAG TAG This measurement, combined with measurements of atmospheric pressure P0atm and temperature T1atm, allows obtaining an image of the aerodynamic forces generated by the gas turbine TAG.

[0070] Gas temperature T4 of gas turbine TAG TAG .

[0071] Torque C driving the electric generators GENA and GENB TAG And low pressure drive shaft N2 TAG From these two measurements, an image of the mechanical power generated by the gas turbine TAG is obtained.

[0072] The alternating current Iac of the two electrical generators GENA and GENB TGA , Iac TGB .

[0073] Output DC power Idc of rectifier REDA and REDB TGA 、Idc TGB .

[0074] DC voltage measured at the reference point of the two channels CA, CB.

[0075] DC power Idc from batteries BATA and BATB BATA 、Idc BATBBy convention, a battery is considered to have positive current when it is being supplied and negative current when it is being charged.

[0076] Alternating current Iac for all motors M1A-M4A, M1B-M4B M1A -Iac M4A / Iac M1B -Iac M4B .

[0077] The temperature of each motor M1A-M4A, M1B-M4B.

[0078] The rotational speed of each drive element H1-H4.

[0079] With reference to FIG3 , the method comprises a step of acquiring ET1 a plurality of measured values ​​Pv of power parameters PARi of the drive system 2. Preferably, the several measured values ​​Pv are represented according to different magnitudes. The acquisition ET1 step is carried out in a known manner from different types of sensors connected to the engine computer CAL.

[0080] For example, Pv is measured, inter alia, as follows:

[0081] The torque C of the gas turbine TAG at its current operating point TAG , the torque C TAG Expressed in Newton meters.

[0082] The alternating current Iac of the two electrical generators GENA and GENB TGA , Iac TGB , the current is expressed in amperes.

[0083] The temperature of each motor M1A-M4A, M1B-M4B, the temperature being expressed in degrees.

[0084] The method comprises a step of comparison ET2 of each measurement value Pv at a power threshold Pseuil determined respectively for each power parameter PAR in order to deduce the overall power margin Pmb of said power parameter PAR.

[0085] In this exemplary embodiment, each power parameter PARi is associated with a power threshold value Pseuil in a threshold value database DB_SEUIL. The engine calculator CAL has access to the threshold value database DB_SEUIL and is thus able to calculate the total power margin Pmb for each power parameter PAR. Preferably, the power threshold value Pseuil is independent of the operating point of the propulsion system. This independence facilitates the calculated power margin to have a predictive value (and therefore, independent of future aircraft maneuvers and, therefore, future operating points of the propulsion system).

[0086] Preferably, each power threshold value Pseuil is specific to a power parameter PARi in the hybrid drive system and preferably specific to the operating point and operating configuration. In addition, each power parameter PARi is associated with a power threshold value Pseuil for each operating point and each operating configuration in a threshold value database DB_SEUIL.

[0087] Preferably, the power threshold Pseuil is expressed in the same order of magnitude as the measurement Pv, which enables the determination of the total power margin Pmb expressed in the same order of magnitude by a simple difference calculation.

[0088] In this example, the following is advantageously achieved:

[0089] The total torque margin of the gas turbine TAG is compared to the maximum torque of the gas turbine TAG at its operating point. The torque margin is expressed in Newton meters.

[0090] The total current margin provided by each electrical generator GENA, GENB, expressed in amperes and

[0091] The total temperature margin of each motor M1A-M4A, M1B-M4B. The temperature margin is expressed in degrees.

[0092] Calculating the overall power margin of the TAG can be complex, especially in the presence of a series-parallel architecture, where a significant portion of the power is borne by the free turbine and the gas generator. The pilot then needs to know the available power margin in each of the two branches in order to be able to adjust the demand accordingly. In this case, it is recommended to calculate the total power margin for each output of the TAG gas turbine. For example, for an architecture in which the free turbine of the gas turbine TAG provides mechanical power to the drive elements H1-H4 and extracts electrical power from the gas generator TAG. The mechanical power margin is calculated based on the equal sampling of the free turbine (electrical equivalent power) on the gas generator and the electrical power margin (on the gas generator) on the free turbine for mechanical equal sampling.

[0093] The method includes the following comparison step ET3: The total power margin Pmb of the power parameter PARi is converted from the conversion ratio database DB_TRANSF into fine power margins Pma expressed according to the same common magnitude. In other words, although the total power margin Pmb is expressed in different magnitudes (Newton meters, amperes, or degrees), the fine power margins Pma are all expressed in the same magnitude, allowing them to be processed together. The fine power margins Pma are all expressed in the same uniform magnitude.

[0094] This uniform magnitude is preferably expressed in Watts, since it allows the power of the drive elements H1 - H4 to be determined. It goes without saying that the uniform magnitude may be different, in particular in torque or amperes.

[0095] Advantageously, the transmission ratio database DB_TRANS is specific to the hybrid drive system 2 and defines the transmission ratios between the power parameters PARi therebetween. The transmission ratios are preferably determined theoretically through energy modeling of the hybrid drive system 2. Each transmission ratio is preferably in the form of at least one mathematical equation that depends on the operating point and configuration of the hybrid drive system 2. This allows the effect of current or temperature changes on the channels, i.e., the torque of the drive elements HI-H4, to be determined. In this example, the transmission ratio database DB_TRANS is stored in a table of the engine calculator CAL.

[0096] In the present example, the total current margin provided by each electrical generator GENA, GENB and the total temperature margin of each electric motor M1A-M4A, M1B-M4B are respectively converted into a fine power margin Pma, which is expressed in Watts.

[0097] The method comprises a substitution step ET4 of replacing a fine power margin Pma for each power parameter PARi (hereinafter referred to as "fine margin Pma") from a yield database DB_REND with a normalized power margin Pmn (hereinafter referred to as "normalized margin Pmn") at one or more reference points of the drive system 2. Preferably, the yield DB_REND is independent of the operating point of the drive system.

[0098] In this example, the reference point is chosen so that it is as close as possible to where the power is actually available for controlling the aircraft, that is, as close as possible to the drive elements H1-H4. For example, a preferred reference point is the mechanical power available on the drive elements H1-H4. Of course, a different reference point can be chosen depending on the requirements or specificities of the drive system 2.

[0099] Advantageously, the yield database DB_REND is specific to the drive system 2 and determines the yield ratios between power parameters thereof, in particular according to the transmission components between the acquisition point and the reference point. Preferably, the yields are theoretically determined by energy modeling of the hybrid drive system 2. Preferably, each yield is in the form of at least one mathematical equation that depends on the operating point and configuration of the hybrid drive system 2. Thus, the fine margin Pma obtained at a given point in the hybrid drive system 2 can be transposed to the same reference point in order to determine the actual margin at said reference point. In this example, the yield database DB_REND is stored in the engine calculator CAL in the form of one or more tables that may depend on other measured parameters (such as the average current level and the channel voltage).

[0100] As an example, the following conversion can be performed: The fine torque margin Pma of the gas turbine TAG, initially represented on the drive shaft of the electric generators GENA, GENB, is converted to the drive shafts of the drive elements H1-H4 (reference point) from the following positions:

[0101] The conversion yield of the generators GENA, GENB and their rectifiers REDA, REDB is 90% in this example;

[0102] The yield of power transmission in channels CANA and CANB is 95% in this example;

[0103] The yield of the motors M1A-M4A, M1B-M4B and their inverters OND1A-OND4A, OND1B-OND4B is 93% in this example.

[0104] Therefore, the fine margin Pma of the gas turbine TAG is converted at a production factor of 80% (90%*95%*93%) on the drive shaft of the drive element HI-H4 to determine the normalized margin Pmn.

[0105] Similarly, the fine power margin Pma of the batteries BATA, BATB, initially represented on their electrical connection terminal strips, is transferred to the drive shafts of the drive elements H1-H4 (reference point) from:

[0106] The transmission yield of power transmission in channels CA, CB, in this example 95%, and

[0107] The yield of the electric motors M1A-M4A, M1B-M4B and their inverters OND1A-OND4A, OND1B-OND4B is 93% in this example.

[0108] Therefore, the fine power margin Pma of the batteries BATA-BATB is converted with a yield factor of 88% (95%*93%) on the drive shafts of the drive elements H1-H4 to determine the normalized margin Pmn. Therefore, the further the reference point is from the measurement location, the more margins are taken into account.

[0109] Furthermore, for the same fine power margin value Pma (expressed in Watts) of 50 kW of gas turbine torque and 50 kW of battery power, the normalized values ​​Pmn on the drive shafts of the drive elements H1-H4 are different (i.e. at the reference point) (normalized gas turbine margin: 50*0.80=40 kW; battery normalized margin: 50*0.85=42.5 kW).

[0110] Still referring to FIG3 , the method includes the following determination step ET5: determining a source power margin for each reference point and a consumer power margin for each reference point. The power margins of the source and the consumer have been proposed, but it goes without saying that the power margin of a power transmission element (e.g., a cable or a transmission shaft) can also be calculated.

[0111] In this example, the power margin for each drive element H1-H4 is determined. These are called individual margins Mind. Therefore, there are as many individual margins Mind as there are reference points; in this example, there are four.

[0112] At a given reference point (a given drive element H1-H4), the source power margin is obtained by adding the normalized margins of the sources supplying that drive element: in our example, the battery BATA, BATB, and the gas turbine TAG. The source power margin MIndS depends on the distribution of the power sources across the drive elements and the configuration of the hybrid drive system (availability or non-availability of power sources). When power sources only supply some of the drive elements H1-H4, the drive element with the lowest normalized margin is selected.

[0113] In other words, for each reference point H1-H4, it is sufficient to trace the power drive system back to the primary source (battery, turbine generator, etc.), taking into account the possible limitations (margins) of each power transmission component encountered on the route.

[0114] If a power source is connected in parallel to supply multiple consumers, the total power is assumed to be distributed equally among each parallel consumer. This assumption of equal distribution is supported by the fact that the topology of the aircraft and its drive system is symmetrical around the center of gravity. However, it goes without saying that a weighted distribution assumption can be implemented when the consumers have very different nominal powers.

[0115] Likewise, at a given reference point, the individual power margins MIndC of the consumers are obtained by adding the normalized margins of the consumers (i.e., motors M1A-M4A, M1B-M4B) that control the reference point. To determine the individual power margins MInd, a selection step ET6 is performed: a minimum power margin is selected between the individual consumer power margins MIndC and the individual source power margins MIndS. In this example, which will be described in detail later, the individual consumer power margins MIndC are limited.

[0116] By tracking the power drive system that supplies a given power component, the individual margin MInd is selected by selecting the margin of the component with the least power.

[0117] When a single power source supplies power to multiple consumers, it's important to consider this distribution and the individual power requirements of each consumer, depending on the mode. For example, a single power source might provide 100 kW and power two electric motors, each providing 60 kW. In this case, the potential available power for each propeller is 60 kW, but the total available power for both propellers is limited to 100 kW due to power source limitations. Therefore, according to the preferred solution of the present invention, the individual margin for each propeller is 50 kW.

[0118] For example, to determine the individual power margin MInd:

[0119] The normalized minimum torque margin is selected from the torque margins of the gas turbine TAG and each generator GENA, GENB and indicates the overall drive torque margin.

[0120] Normalized minimum torque margin of the motors M1A-M4A, M1B-M4B between different limiting factors, such as temperature limits, inverter current limits or current limits of the power supply dedicated to the motors M1A-M4A, M1B-M4B.

[0121] The individual power margins MInd of each drive element H1-H4 inform the pilot about the drive power available for action according to the aircraft's attitude, thus contributing to flight stability (for example: the power margin on each right motor provides information about the aircraft's ability to roll to the left). Advantageously, in the case of an even distribution, the pilot only needs to respect all the individual power margins to verify the control law.

[0122] Alternatively, when the driven elements have very different nominal powers, the total power received by the node is weightedly distributed among the driven elements.

[0123] Depending on the control system's preferences, various types of indications can be made. In the previous example, a separate margin MInd was selected for each drive element H1-H4. The advantage of these indications is that they provide the control system with very good visibility into the "controllability" of the aircraft.

[0124] The individual power margins MInd can also be grouped by the main axes of the aircraft, indicating the margins for roll, pitch and yaw. This solution provides a more synthetic and "formatted" indication in a known reference system of the control system.

[0125] An example of a detailed implementation will be described with reference to FIG4 .

[0126] In this example, with reference to FIG. 4 , there is an acquisition ET1 step: acquisition of measured values ​​Pv of a plurality of power parameters PARi of the hybrid drive system 2 , in particular at the level of the gas turbine TAG, the batteries BATA, BATB and the electric motors M1A-M4A, M1B-M4B.

[0127] The following comparison ET2 step is then performed: each measured value is compared with several limit thresholds (i.e., within the limits that have been verified). Preferably, the limit thresholds correspond to the time for which the power parameter PARi can be maintained. This is particularly true for the parameters of the gas turbine TAG, where at least two operating regimes are usually distinguished:

[0128] The institutional threshold PMD is for the maximum takeoff power that can be maintained for a limited time, usually between 10 min and 30 min;

[0129] The regime threshold PMC, for continuous maximum power, can be maintained indefinitely.

[0130] It goes without saying that other thresholds can be specified, for example, an emergency regime that can reach higher power levels, but may have a limited duration. Similarly, some power equipment may have several current limits that can be maintained for different lengths of time. Therefore, the margin separating each parameter from its certified limit is calculated. For example, referring to Figure 5, the following margins are calculated:

[0131] Under the atmospheric conditions measured at the time, P0 atm and T1 atm, the limits for the TAG gas turbine speed N1TAG corresponding to the PMD (duration 10 mn) and PMC regimes were 100% and 95%, respectively. Therefore, for 98% of the measured values, the total N1TAG margin for each regime was: MN1_PMD = +2% and MN1_PMC = -3%.

[0132] Likewise, for the T4TAG turbine drive temperature, the PMD and PMC regulatory limits are 100% and 94%, respectively. For 96% of the measured values, the total temperature margin for the T4TAG is: MT4_PMD = +4% and MT4_PMC = -2%.

[0133] Torque limit C generated by gas turbine TAG TAG is unique, being 40 Nm. For a measured value of 32.8 Nm, the total torque margin is MCT = +7.2 Nm.

[0134] The current limit of the battery BATA is 160 A continuously and 180 A for 2 minutes. Therefore, two current margins of the battery BATA are also calculated: the total margin limit is 2mn MIdcBATA_2mn=+172 A and the continuous total margin MIdcBATA_PMC=152 A. The same applies to the secondary battery BATB.

[0135] The AC limits for motors M1A-M4A, M1B-M4B are 49A permanently and 54A for 2 minutes. Calculate the two current total margins for each motor:

[0136] Engine 1A: For the current measurement IacM1A of 30A, the total margin limit is 2mn MM1A_2mn=+24A, and the continuous total margin MM1A_PMC=+19A.

[0137] Motor 1B: For the current measurement IacM1B of 30A, the total margin is limited to 2mn MM1B_2mn=+24A, and the continuous total margin MM1B_PMC=+19A.

[0138] Engine 2A: For the current measurement IacM2A of 28A, the total margin limit is 2mn MM2A_2mn=+26A, and the continuous total margin MM2A_PMC=+21A.

[0139] Perform the same run for the other devices in the system until margins are obtained for all parameters.

[0140] The comparison ET3 step and the permutation ET4 step convert and permute each margin calculated in the previous step to a uniform magnitude at one or more reference points, preferably at the output of the hybrid drive system. In this example, the reference point is the first drive element H1.

[0141] For the gas turbine TAG limit, at the current operating point, the latter model allows N1 TAG and T4 TAG The margin is converted to an equivalent power margin at turbine output. Using this model, the calculator CAL determines the following conversion:

[0142] MN1_PMD=+15.7kW and MN1_PMC=-20.9kW

[0143] MT4_PMD = +17.8kW and MT4_PMC = -18.3kW

[0144] MCT = +18.8kW (PMD and PMC)

[0145] After these conversions, the method selects the minimum torque margin for the gas turbine TAG. In this example, the overall minimum torque margin is: MTAG_PMD = +15.7kW, MTAG_PMC = -20.9kW (limited by N1TAG in this example) (Figure 5).

[0146] The method then converts the total margin of the gas turbine TAG to the drive elements H1-H4 by following the power drive system and applying the successive yields of each drive element.

[0147] Referring to Figure 6, applied to our example at the reference point of the first drive element H1, based on the assumption of equal distribution at the connection nodes of the motors M1A and M2A, the minimum margins MTAG_PMD and MTAG_PMC of the gas turbine TAG become:

[0148] MTAG_PMD=+11.4Nm

[0149] MTAG_PMC=-15Nm

[0150] For the margin of the main battery BATA, the DC margin is first converted into the electrical energy available at the battery output using the voltage measurement Vdc of the main channel CANA provided by it. Therefore, the margin expressed in power is:

[0151] The margin limit is 2mn MIdcBATA_2mn = +103kW

[0152] Continuous margin MIdcBATA_PMC = 91.2kW

[0153] Converting these margins into the torque available to the drive elements H1-H4, taking into account the output of the drive system, we obtain:

[0154] MIdcBATA_2mn=+158Nm

[0155] MIdcBATA_PMC=+140Nm

[0156] The motor limits M1A-M4A, M1B-M4B are also converted using the motor model to the torque margin available on each drive element H1-H4. In this example, this conversion gives the following results:

[0157] Engine 1A: MM1A_2mn = +61 Nm and MM1A_PMC = +48.5 Nm.

[0158] Engine 1B: MM1B_2mn = +61 Nm and MM1B_PMC = +48.5 Nm.

[0159] Engine 2A: MM2A_2mn = +66 Nm and MM2A_PMC = +53.6 Nm.

[0160] In this example, a drive architecture is described for nominal conditions (fault-free), where all power sources (batteries BATA, BATB, gas turbine TAG) supply all drive elements H1-H4, so there is no need to select a power source that is more restrictive than the others.

[0161] Therefore, MindCA indicates that the individual power margin at the battery BATA (or BATB) node on the main power channel CA (or CB) corresponds to the sum of the margins of the battery and the turbine generator, evenly distributed over the four engines (M1A-M4A) supplied by this main channel. The following relationship is obtained:

[0162] MindCA_2mn=MTAG_PMD+MIdcBATA_2mn

[0163] MindCA_2mn=11.4Nm+158Nm=+169.4Nm

[0164] MindCA_PMD=MTAG_PMD+MIdcBATA_PMC

[0165] MindCA_PMD=11.4Nm+140Nm=+151.4Nm

[0166] MindCA_PMC=MTAG_PMC+MIdcBATA_PMC

[0167] MindCA_PMC=-15Nm+140Nm=+125Nm

[0168] The same operation is performed for the margin MindCB of the secondary channel CB.

[0169] Preferably, when a component does not have a specific power limit within a given timeframe, the method uses the power margin for the next higher timeframe. For example, the power margin PMD of the gas turbine TAG is used to calculate the margin MindCA_2mn. Similarly, the power margin PMC of the batteries BATA and BATB is used to calculate the margin MindCA_PMD.

[0170] Finally, the method includes a comparison step: the power margin of the power source is compared with the power margin of the consumers. In the nominal case of the example, the power margin of the electric motor is the lowest. Therefore, the limit corresponding to the drive element with the lowest margin is applied. Therefore, the power margin of the drive system indicated by the method according to the invention is:

[0171] MH1_2mn=min(MindCA_2mn; MM1A_2mn)+min(MindCB_2mn; MM1B_2mn)

[0172] MH1_2mn=+122Nm=min(169.4Nm; 61Nm)+min(169.4; 61Nm)

[0173] MH1_PMD=min(MindCA_PMD; MM1A_PMD)+min(MindCB_PMD; MM1B_PMD)

[0174] MH1_PMD=+97Nm=min(151.4Nm;48.5Nm)+min(151.4;48.5Nm)

[0175] MH1_PMC=min(MindCA_PMC; MM1A_PMC)+min(MindCB_PMC; MM1B_PMC)

[0176] MH1_PMC=+97Nm=min(125Nm;48.5Nm)+min(125;48.5Nm)

[0177] Without going into detail about calculations similar to those above, assuming that motors M2A-M2B have the same power margin, the following results are obtained by way of example:

[0178] MH2_2mn=132Nm; MH2_PMD=107Nm; MH2_PMC=107Nm

[0179] As shown in Figure 3, different individual power margins can be displayed on the aircraft instrument panel to inform the pilot of power reserves and possible operations. Various power margins can also be stored in the engine calculator CAL for use by the autopilot.

[0180] The interpretation of these margins is that the pilot has an instantaneous power reserve, corresponding to a torque of +122 Nm for 2 minutes and +97 Nm permanently on the H1 propeller, to perform all possible maneuvers, whether accelerating or increasing altitude or changing the attitude of the aircraft. The pilot must distribute this available power margin between these different maneuvering possibilities so that the overall maneuver respects all the individual margins of all the propellers.

[0181] The pilot also knows that as long as he / she simultaneously maintains a positive individual margin, he / she will be able to perform all the maneuvers he / she wishes without restriction.

[0182] Advantageously, a method for controlling an aircraft including a hybrid drive system may be implemented in a safe manner by a control system that may be manual or automated.

[0183] 7 , the control system is configured to determine control commands O_PIL of the aircraft in relation to the power requirement BP. In practice, in a known manner, each control command O_PIL requires more or less power depending on the nature of the sequence (avoidance, take-off, acceleration, etc.).

[0184] The control method comprises the following determination step: determining at least one minimum power margin, in particular an individual minimum power margin MInd, of the drive system by means of a method such as that described above.

[0185] The control method comprises a step of verifying the control command O_P1L if the power requirement BP is less than the minimum power margin MInd, and preferably a step of rejecting the control command O_P1L if the power requirement BP is greater than the minimum power margin MInd. Thus, the control command O_P1L, which can be dynamically accepted during the flight of the aircraft, is passive and provided in anticipation.

Claims

1. A method for determining at least one minimum power margin of a hybrid drive system (2) for a transport vehicle, the drive system (2) comprising a plurality of power sources of different nature, a plurality of power consumers and a plurality of drive elements (H1-H4), each drive element (H1-H4) being associated with at least one power source and at least one power consumer, the method comprising: An acquisition (ET1) step of acquiring measured values ​​(Pv) of a plurality of power parameters (PARi) of the hybrid drive system (2), wherein at least two measured values ​​(Pv) are represented according to different magnitudes; a comparison (ET2) step of comparing each measured value (Pv) with at least one limiting threshold value (Pseuil) determined for each power parameter (PARi) of a threshold value database (DB_SEUIL) in order to deduce therefrom at least one overall power margin (Pmb) of said power parameter (PARi); a conversion (ET3) step of converting the total power margin (Pmb) of said power parameters (PARi) from a conversion database (DB_TRANS) into a fine power margin (Pma) expressed according to the same common magnitude; a substitution (ET4) step of substituting a refined power margin (Pma) from a production database (DB_REND) determining the production of the transmission components between the acquisition point and the reference point into a normalized power margin (Pmn) at at least one reference point of the hybrid drive system (2); a determination (ET5) step of determining a source power margin (MIndS) from the normalized power margin of the source (Pmn) at the reference point and determining a consumer power margin (MIndC) from the normalized power margin of the consumer (Pmn) at the reference point; • Determination (ET6) step: determining a minimum power margin (MInd) by selecting the lowest power margin between the consumer power margin (MIndC) and the source power margin (MIndS) at said reference point.

2. The method according to claim 1, wherein The reference point corresponds to one or more drive elements (H1-H4).

3. The method according to claim 1, wherein When a power source supplies a plurality of power consumers in parallel, it is assumed that the total power received in the node is evenly distributed among the power consumers.

4. The method according to claim 1, wherein When a power source supplies multiple power consumers in parallel, the total power received in the node is distributed among the power consumers in a weighted manner.

5. The method according to claim 1, wherein The drive system (2) comprises at least one turbine generator (TG) and at least one battery (BATA, BATB) as power sources.

6. The method according to claim 1, wherein The drive system (2) includes a plurality of electric motors (M1A-M4A, M1B-M4B) as power consumers.

7. The method according to claim 1, wherein For aircraft, individual power margins (Mind) are grouped along the main axes of the aircraft to indicate roll, pitch, and yaw margins.

8. A method of controlling a transportation vehicle including a hybrid drive system by a control system, the method comprising: Determining step: determining a control command of the transport vehicle by the control system, wherein the control command is associated with the power demand; Determining step: determining at least one minimum power margin of the drive system (2) by a method according to any one of claims 1 to 7, and Verification step: If the power demand is less than the minimum power margin, the control command is verified.

9. A hybrid drive system for a transport vehicle, the drive system (2) comprising a plurality of power sources, a plurality of power consumers and a plurality of drive elements (H1-H4), each drive element (H1-H4) being associated with at least one power source and at least one power consumer, the drive system (2) comprising at least one calculator (CAL) and a database (DB_SEUIL, DB_TRANS, DB_REND) accessible to the calculator (CAL), the calculator (CAL) being configured to: Acquiring (ET1) measured values ​​(Pv) of a plurality of power parameters (PARi) of a hybrid drive system (2), representing at least two of the measured values ​​(Pv) according to different magnitudes; comparing (ET2) each measured value (Pv) with at least one limiting threshold value (Pseuil), which is determined for each power parameter (PARi) of a threshold value database (DB_SEUIL) in order to deduce therefrom at least one overall power margin (Pmb) of said power parameter (PARi); converting (ET3) the total power margin (Pmb) of said power parameters (PARi) from a conversion database (DB_TRANS) into a fine power margin (Pma) expressed according to the same common magnitude; Transposing (ET4) a refined power margin (Pma) from a yield database (DB_REND) determining the yield of the transmission elements between the acquisition point and the reference point into a normalized power margin (Pmn) of at least one reference point; determining (ET5) a source power margin (MIndS) from the normalized power margins of the sources (Pmn) at the reference point, and determining a consumer power margin (MIndC) from the normalized power margins (Pmn) of the consumers at the reference point; • determining (ET6) a minimum power margin (MInd) by selecting the lowest power margin between the consumer power margin (MIndC) and the source power margin (MIndS) at said reference point.

10. A transport vehicle comprising at least one hybrid drive system according to claim 9.

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