Mechatronic system for managing the failure of an aircraft engine

Abstract

Disclosed is a mechatronic system (1) tolerant to a simple electrical failure of a hybrid-electric or electric machine for an aircraft, the mechatronic system (1) comprising an electric machine (2) and at least two electronic circuits (3a, 3b) each comprising at least one energy accumulator (5a, 5b) and at least one converter (7a, 7b) positioned downstream of the energy accumulator (5a, 5b), the electric machine (2) being connected to the engine of the aircraft and to the electronic circuits (3a, 3b). The electronic circuits (3a, 3b) each comprise at least one symmetrization member (8a, 8b) for symmetrizing an electrical failure, comprising at least one failure symmetrization branch per phase signal (a, b, c, a', b', c') at the output of the converter (7a, 7b), connected to an associated phase (A, B, C, A', B', C') of the electric machine (2), the electric machine (2) comprising at least two magnetically independent three-phase stars (4a, 4b).

Description

[0001] DESCRIPTION

[0002] TITLE: MECHATRONIC SYSTEM FOR CONTROLLING AN AIRCRAFT ENGINE FAILURE

[0003] technical field

[0004] The invention relates technically to mechatronic systems and more particularly to a mechatronic system for failure tolerance of an aircraft engine.

[0005] The invention relates to reducing fuel consumption and improving the safety of aircraft and electric aircraft propulsion systems. The invention specifically concerns managing the occurrence of short circuits in a hybrid or electric aircraft engine.

[0006] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0007] Technological research efforts have already led to significant improvements in the environmental performance of aircraft. The Applicant takes into account all relevant factors at every stage of design and development to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving aircraft energy efficiency. Consequently, the Applicant is continuously working to reduce its negative climate impact by employing environmentally sound methods and processes for development and manufacturing that minimize greenhouse gas emissions to the absolute minimum possible, thereby reducing the environmental footprint of its operations.

[0008] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter onboard equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0009] In the case of an electric propeller driven by a permanent magnet motor located on the rotor, the magnets continue to rotate even when the motor is no longer powered. This generates an excitation current and, in the event of a failure, can cause a short-circuit current in the stator windings. This is because, typically, when the motor is no longer powered, an external airflow drives the propeller, which continues to rotate and thus drives the rotation of the motor's magnets.

[0010] The problem in this scenario is that the short-circuit current generated in the motor creates a resistive torque opposing the motor's rotational torque due to the propeller's autorotation. Depending on the propeller's rotational speed, the equilibrium point between the short-circuit torque and the propeller's autorotation torque may occur at inert currents. This means that the short-circuit current in the motor persists and that the short circuit is insufficient to stop the propeller's autorotation. However, the short-circuit current may be high enough to generate excessive heat that would damage the motor and its surroundings.

[0011] A similar situation is illustrated by Figure 1. Indeed, the situation presented in Figure 1 involves an aircraft of N knots comprising an engine and a propeller, said propeller implying autorotation according to three different pitch settings ranging from a degrees to P degrees and the engine implying a short circuit in the stator winding.

[0012] Figure 1 graphically represents, with solid curves, the evolution of the propeller's autorotation torque in Nm and, with a dotted curve, the evolution of the motor's short-circuit torque in Nm, according to the increase in the motor's rotational speed in rpm.

[0013] The short-circuit torque of the motor intersects the autorotational torques of the propeller at several points. These intersections define the equilibrium point between the autorotational torque of the propeller and the resisting torque caused by the short circuit.

[0014] In the case of a propeller pitch of P degrees, we observe that the equilibrium point between the propeller's autorotational torque and the short-circuit torque is non-zero. Thus, the machine continues to rotate at an equilibrium propeller speed of 0 rpm and with a non-zero short-circuit torque, and consequently a non-zero short-circuit current.

[0015] This situation can lead to risks of overheating or even breakage in the aircraft, which is what we are trying to avoid.

[0016] Previous techniques

[0017] Document FR3027058 describes an electrotechnical system designed to improve the resilience of in-flight reactivations to failures, notably by providing complete redundancy of electrotechnical components, including electric motors and their power electronics that control the electrical currents within these machines. The proposed solution also includes additional energy storage systems to enable rapid reactivation of the electric machines. However, such a complete redundancy solution is very costly in terms of onboard mass.

[0018] Description of the invention: The present invention is the result of technological research aimed at significantly improving aircraft performance and, in this respect, contributes to reducing the environmental impact of aircraft. To this end, the invention aims to provide improved control of electrical currents in aircraft engines without affecting their mass.

[0019] The invention therefore relates to a mechatronic system tolerant to a single electrical failure in a hybrid-electric or electric aircraft engine, said mechatronic system comprising an electric engine and at least two electronic circuits, each comprising at least one energy storage unit and at least one converter positioned downstream of the energy storage unit, the electric engine being connected to the aircraft engine and the electronic circuits. Each of the electronic circuits includes at least one electrical failure symmetrization device comprising at least one phase-signal symmetrization branch at the converter output connected to an associated phase of the electric engine, the electric engine comprising at least two magnetically independent three-phase star connections.

[0020] Advantageously, each branch of symmetrization includes a short circuiter.

[0021] According to one embodiment, the short-circuiter is pyrotechnically operated.

[0022] Advantageously, each symmetrization branch further includes a resistor in series with the short-circuiter of said branch.

[0023] According to one embodiment, a control function of the symmetrizing device is configured to simultaneously control the closing of the short-circuiter of each symmetrizing branch as a function of a measurement of the current on each phase signal.

[0024] Advantageously, the mechatronic system includes a supervisory element configured to apply a fault tolerance strategy including detection of an electrical fault based on the measurement of phase signal currents and symmetrization of a detected electrical fault by activating the control function of the symmetrization device.

[0025] According to one embodiment, the fault tolerance strategy is such that the symmetrization of the detected electrical fault includes the activation of the control function of the symmetrization device before an internal symmetrization control function of the converter arms.

[0026] Advantageously, the fault tolerance strategy further includes an activation condition for the internal symmetrization control function of the converter arms, such that said control function is or is not activated as a function of a current measurement on each phase signal.

[0027] The invention also relates to an engine comprising a mechatronic system as defined above.

[0028] The invention also relates to an aircraft comprising a mechatronic system as defined above.

[0029] Brief description of the drawings

[0030] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0031] - Figure [Fig 1] graphically illustrates the evolution of the autorotation torque of the propeller of an aircraft and the evolution of the short-circuit torque in the aircraft engine according to the engine's rotation speed;

[0032] - Figure [Fig 2] schematically illustrates a failure-tolerant mechatronic system for an aircraft engine;

[0033] - Figure [Fig 3A] schematically illustrates an example of a short-circuit situation in one of the electromechanical channels of the mechatronic system in Figure 2; - Figure [Fig 3B] schematically illustrates the symmetrization of the short circuit in Figure 3A in one of the electromechanical channels of the mechatronic system in Figure 2, and

[0034] - Figure [Fig 4] schematically illustrates the steps in setting up a fault tolerance strategy for one of the electromechanical channels of the mechatronic system in Figure 2.

[0035] Detailed description

[0036] During a flight, an aircraft goes through a takeoff phase requiring relatively low specific fuel consumption, a cruise phase requiring moderately high specific fuel consumption, a descent phase, and a taxi phase requiring high specific fuel consumption. For a helicopter, the landing phase requires relatively low specific fuel consumption. Specific fuel consumption represents the amount of fuel consumed per unit of power produced by the aircraft's engine (expressed in liters of fuel / km / kW). In the case of electric propulsion systems, specific fuel consumption represents the amount of electrical energy consumed per unit of power produced by the aircraft's electric propulsion system.

[0037] Thus, in the case of a twin-engine helicopter in cruise mode, characterized by moderate power demand, one of the two engines is put on standby so that the second engine operates at high RPM, improving the overall efficiency of the propulsion system while minimizing engine specific fuel consumption. The twin-engine helicopter can, for example, be hybrid-electric or purely electric.

[0038] The invention applies in particular to the rapid or normal in-flight reactivation of one of the turboshaft engines of an aircraft. It then makes it possible to ensure different operating modes such as the ground start of the aircraft's gas turbine by means of a function of the electric starter of said turbine, the standby mode of the turbine's gas generator, the in-flight reactivation of the turbine previously put into standby mode, i.e. the turbine's combustion chamber is turned off, and the rapid in-flight reactivation of the turbine previously put into standby mode.

[0039] Another use case for the mechatronic system concerns the electric or hybrid-electric propulsion of the aircraft where the engine must be tolerant of simple failure and not cause catastrophic events.

[0040] The mechatronic system also relates to electrical generation and the use of this mechatronic system so that the loss of one or more electrical power circuits does not lead to the total loss of electrical power supply on board the aircraft.

[0041] Thus, the idea behind the invention is to provide an electrical power generation or propulsion system for an electric or hybrid-electric aircraft that ensures, in the event of a system failure, continued flight or a safe landing. To guarantee this continuity of service, the mechatronic system is designed to ensure redundancy, segregation, independence of electromechanical channels, and symmetrization of electrical failures.

[0042] The invention relates to a mechatronic system powered by the aircraft's native on-board network, enabling flight safety by isolating electrical failures that an aircraft may experience and adapted to different use cases.

[0043] Figure 2 shows a mechatronic system, designated by the general numerical reference 1. The mechatronic system 1 comprises an electrical machine 2 with at least two polyphase star connections and at least two associated electronic control circuits 3a, 3b, one per star, each electronic circuit having its own power supply. Each electronic circuit, its power supply, and its associated star connection form a segregated electromechanical channel independent of the other electromechanical channel(s). The electrical machine 2 is connected to an aircraft load and is controlled by the electronic circuits 3a, 3b. The aircraft load is, for example, an actuator or a propulsion system. The electrical machine 2 has at least two polyphase star connections, generally three-phase, 4a, 4b.Stars 4a and 4b are magnetically independent, meaning that magnetic phenomena occurring on one star have little or no influence on the other. The mutual inductance phenomenon is thus considered negligible between the two stars 4a and 4b. The double-winding electric machine 2 comprises a single magnetic circuit consisting of a single stator and a single rotor within a housing, resulting in minimal mass. The magnetically independent three-phase stars 4a and 4b of electric machine 2 allow for a more balanced distribution of electrical currents. This reduces electrical disturbances and improves the electrical stability of system 1. It also provides modularity in the operation of system 1. Electric machine 2 can be a permanent magnet synchronous motor, a variable reluctance synchronous motor, or an asynchronous motor.

[0044] The mechatronic system 1 is redundant in order to improve the safety of the system compared to a simple, non-redundant system architecture. The mechatronic system 1 therefore comprises at least two electronic circuits 3a, 3b.

[0045] In the embodiment illustrated in Figure 2, system 1 comprises a first electronic circuit 3a connected to a first three-phase star connection 4a of the electrical machine 2 and a second electronic circuit 3b connected to a second three-phase star connection 4b of the electrical machine 2. The two circuits 3a and 3b are completely segregated and independent, meaning they are spatially separated and galvanically isolated from each other according to best practices. Thus, circuit 3a has no influence on circuit 3b and vice versa. When one of the circuits 3a and 3b fails, the other circuit 3a and 3b remains unaffected. The combination of a circuit 3a and 3b with a three-phase star connection 4a and 4b constitutes an electromechanical channel. The mechatronic system 1 thus comprises two redundant, segregated and independent electromechanical channels.

[0046] The electronic circuits 3a, 3b are similar, each comprising, in the direction of power supply from an upstream side to a downstream side, an energy storage unit 5a, 5b, each storage unit being connected to an on-board HVDC network 22a, 22b, and a converter 7a, 7b. A protection component 6a, 6b is generally provided between the energy storage unit 5a, 5b, and the converter 7a, 7b.

[0047] The converters 7a, 7b each comprise three phase outputs a, b, c, a', b', c' each connected to a corresponding phase A, B, C, A', B', C' of the three-phase star 4a, 4b associated in a respective node Aal, Bb l, Cc l, Aal', Bb l', Cc l'.

[0048] The energy storage unit 5a, 5b is, for example, an electrochemical storage unit such as a battery, an electrolytic storage unit, or a flywheel storage unit. The energy storage unit 5a, 5b delivers a direct current that is converted to alternating current by the DC / AC converter 7a, 7b. The energy storage unit 5a, 5b can be rechargeable or non-rechargeable. More specifically, when the turbomachine is in motor mode, the energy storage unit 5a, 5b is either rechargeable or non-rechargeable, and when the turbomachine is in electricity generation mode, the energy storage unit 5a, 5b is rechargeable.

[0049] The protection component 6a, 6b can be a protection diode or a short circuiter and prevents the propagation of electrical faults from downstream components to the energy storage 5a, 5b.

[0050] The 7a, 7b converter can be a DC-to-AC converter or a reversible converter. The 7a, 7b converter is reversible when the 5a, 5b battery is rechargeable.

[0051] According to the invention, the electronic circuits 3a, 3b further comprise a symmetrization device 8a, 8b for electrical failures, positioned downstream of the converter 7a, 7b and connected to the associated three-phase star connection 4a, 4b. The symmetrization device 8a, 8b is designed to minimize the consequences of an electrical failure on the electronic circuit 3a, 3b, in particular to reduce the current stresses on the switching cells of the converters 7a, 7b. The symmetrization device 8a, 8b allows the currents associated with the electrical failure to be controlled to make them as harmless as possible to the other electronic components of the mechatronic channel under consideration, by providing them with a low-impedance path.

[0052] The symmetrizing organ 8a, 8b includes a symmetrizing branch by phase signal a, b, c, a', b', c' at the output of the converter 7a, 7b and each symmetrizing branch is connected to the corresponding phase input A, B, C, A', B', C' of a star 4a, 4b of the electrical machine 2.

[0053] Each symmetrization branch includes a controllable short circuiter 10 connected to the respective phase node Aal, Bbl, Ccl, Aal', Bbl', Ccl' and a resistor 9 in series between the short circuiter 10 and a floating electrical node allowing the bypass and dissipation of current when the short circuiter 10 is activated, i.e. closed, equivalent to a short circuit.

[0054] Each symmetrization branch is thus connected to a respective connection node Aal, Bbl, Ccl, Aal', Bbl', Ccl', between a respective phase A, B, C, A', B', C' of the three-phase star 4a, 4b and a respective phase output a, b, c, a', b', c' of the converter 7a, 7b. Each connection node Aal, Bbl, Ccl, Aal', Bbl', Ccl', is advantageously positioned as close as possible to the corresponding stator winding of the star 4a, 4b of the electrical machine 2. According to one embodiment, the symmetrization branches and the respective connection nodes Aal, Bbl, Ccl, Aal', Bbl', Ccl' are integrated into the electrical machine 2.

[0055] The resistors are chosen such that, when the short circuits are closed, the symmetrization branches form low-impedance paths, with an impedance lower than that of the converter. The symmetrization device 8a, 8b acts on the electrical currents to limit torque ripples in the electrical machine 2 caused by an electrical fault located in the electrical machine 2 or in one of the upstream electronic components. If the torque ripples in the electrical machine 2 are not controlled, they can lead to excessive vibrations, loud noise, or premature wear of the aircraft components, which is what we want to avoid.

[0056] The symmetrization device 8a, 8b constitutes a hardware component of a fault tolerance strategy, which involves external symmetrization of the converter 7a, 7b. When the converter's control electronics 7a, 7b are used in the fault tolerance strategy, they drive internal symmetrization within the converter by controlling the switching cells, as explained later. The converter's switching cells are then placed in a specific configuration to ensure internal fault symmetrization within the converter.

[0057] Thus, the fault tolerance strategy proposed in this document uses symmetrizing devices 8a, 8b, which are external to the converters 7a, 7b and located downstream of them. Advantageously, they are positioned as close as possible to the star connections of the electrical machines 4a, 4b. They are designed to provide a low-impedance path for the electrical fault current, thereby reducing the current stress on the associated converter 7a, 7b, and to be activated before any internal symmetrization function of the converter is required. The external and internal symmetrizations can be performed in combination, or only the external symmetrization can be performed.

[0058] Figures 3A and 3B schematically represent an electromechanical channel including the DC / AC converter 7a driving a star connection 4a of the electrical machine 2, with specific internal functions proposed. The architecture of an electromechanical channel including the DC / AC converter 7b driving a star connection 4b is identical. The invention is described in more detail hereafter, using the electromechanical channel including the DC / AC converter 7a as an example. Everything described applies equally to the other electromechanical channel(s) of the same architecture.

[0059] The DC / AC converter 7a comprises three switching arms X, Y, Z, one for each phase signal to be produced at output a, b, c, which are powered in parallel by the DC voltage source. The DC / AC converter 7a conventionally includes a decoupling capacitor 19 in parallel with the DC power supply, upstream of the switching arms X, Y, Z.

[0060] A current sensor 20 is conventionally provided on each phase at output a, b, c of the converter 7a for the control of the electrical machine 2. The tolerance strategies and associated electrical fault symmetrization functions use the current measurements provided by the sensors 20 for the detection of electrical faults.

[0061] Each X, Y, Z switching arm comprises a pair of series switching cells; the connection node between the two cells of each pair forming the output node Aa2, Bb2, Cc2 delivering the respective phase signal a, b, c.

[0062] The first phase output a of converter 7a is applied to node Aal (not shown in figures 3A and 3B) connected to a first branch of the symmetrizing element 8a and to a corresponding phase A of the star 4a of the electrical machine 2; the second phase output b of converter 7a is applied to node Bb l (not shown in figures 3A and 3B) connected to a second branch of the symmetrizing element 8a and a corresponding phase B of the star 4a of the electrical machine 2; the third phase output c of converter 7a is applied to node Cc l (not shown in figures 3A and 3B) connected to a third branch of the symmetrizing element 8a and a corresponding phase C of the star 4a of the electrical machine 2.

[0063] Figure 3A illustrates an example of an asymmetric electrical failure situation. In this example, the fault is located in electrical machine 2, corresponding to a DC short circuit between phases B and C of the star connection 4a of electrical machine 2, which here results in short-circuiting the switching cells 16 and 17. These two cells 16 and 17 then form a low-impedance electrical path, which induces a significant excess of current delivered by the capacitor 19, damaging the switching cells 16 and 17.

[0064] Another example of an asymmetric electrical failure situation is, for example, a short circuit between a phase and the chassis of electrical machine 2.

[0065] We have already explained previously the adverse effects of torque ripple on the mechanical part induced by this type of asymmetric electrical failure.

[0066] The protection component 6a, 6b, positioned upstream of the converter 7a, 7b as illustrated in Figure 2, can be designed to prevent the propagation of the DC short circuit upstream of the converter 7a, 7b, thus protecting, in particular, the energy storage device 5a, 5b. Furthermore, a fault tolerance strategy is known that relies on activating an internal symmetrization function of the converter. This is implemented by a control function Fl of the X, Y, Z arms of the converter 7a, 7b, which allows the fault to be symmetrical within the converter 7a, 7b, and consequently, the components located upstream of the converter 7a, 7b to be isolated as shown.

[0067] Function F is activated in practice upon detection of an asymmetric electrical fault based on phase current measurements taken by current sensors 20 and 20', and configured to control the opening and closing of the switching arm cells of converter 7a and 7b according to a fault symmetrization configuration. Current sensors 20 and 20' are, in practice, those used for controlling the electric motor (servo control) as previously described.

[0068] Figure 3B illustrates the corresponding configuration of the switching arm cells of converter 7a, controlled by function Fl, for symmetrizing an electrical fault. The "lower" cells 14, 16, 18 connected to the negative supply terminal 12 are in the closed position, i.e., conducting, and the "upper" cells 13, 15, 17 connected to the positive supply terminal 11 are in the open position, i.e., non-conducting. The architecture of the electromechanical channel including the DC / AC converter 7b driving the star connection 4b is identical.

[0069] This configuration smooths out torque ripples in the event of a detected electrical fault. However, it does not significantly limit the current seen by the short-circuited, low-impedance switching cells, as explained previously, consequently increasing the risk of damaging these cells.

[0070] Also, to minimize the current stress on the converter 7a, 7b and improve the passivation of the failure in the mechatronic system 1, it is proposed to implement an external symmetrization to the converter, by means of the symmetrization element 8a, 8b external to the converter 7a, 7b, downstream of it and controlled by a control function F2, intended to be activated before the control function F1 controlling an internal symmetrization of the converter 7a, 7b in order to reduce the current stresses in the latter.

[0071] As previously mentioned, the symmetrization unit 8a, 8b comprises symmetrization branches with resistors in series with short-circuiters. The resistances are such that, when the short-circuiters are switched on by the control function F2, the symmetrization branches form paths with an impedance lower than the internal impedance of the converter 7a, 7b. This results in the DC short-circuit current being shared between the symmetrization branches and the converter 7a, 7b, thereby reducing the current load on the converter 7a, 7b.

[0072] The symmetrization unit 8a, 8b comprises a symmetrization branch per phase output a, b, c, a', b', c' of the converter 7a, 7b as described previously in connection with Figure 2. Each branch is connected to a connection node to the corresponding machine phase, preferably positioned close to the corresponding stator winding of the electric machine 2. The function F2 is configured to simultaneously close the three short-circuiters 10 of the symmetrization unit 8a, 8b when a DC short-circuit current is detected, based on the current measurements provided by the current sensors 20, 20', allowing the dissipation of DC short-circuit current in the symmetrization branches and thus reducing the current stress on the converter 7a, 7b.

[0073] As illustrated in Figure 2, the mechatronic system 1 comprises two general supervisory elements 21, 21' respectively connected to the electronic circuits 3a, 3b, which allow control of the various electronic components of the system 1, in particular the switching arms X, Y, Z of the converter 7a, 7b and the symmetrization branches of the symmetrization organ 8a, 8b of the mechatronic system 1.

[0074] The monitoring element 21, 21' can be located either directly within the intelligence of the converter 7a, 7b, or in a supervisor independent of the converter 7a, 7b. If the monitoring element 21, 21' is located in a separate supervisor, communication between said monitoring element 21, 21' and the symmetrization devices 8a, 8b must be fast and efficient. The monitoring element 21, 21' can also be a single monitoring element.

[0075] Figure 4 illustrates the steps in implementing a fault tolerance strategy for the electromechanical channel including the DC / AC converter 7a driving the star 4a. The steps not shown in implementing a fault tolerance strategy for the electromechanical channel including the DC / AC converter 7b driving the star 4b are identical.

[0076] Conventionally, a current sensor 20 is provided on each phase signal, for the control of the electric machine 2.

[0077] In this document, the current measurement on each phase signal is also used to detect electrical faults, particularly asymmetric electrical faults, in order to activate a fault tolerance strategy involving, among other things, the activation of control function F2. In the example, the monitoring element 21 receives current measurements from the current sensors 20 and processes them to detect the occurrence of an electrical fault, specifically an asymmetric type. In one example, such a fault is detected if the current measured on a phase exceeds a given current threshold.

[0078] Detecting such a fault can also consider the difference between the currents of the two phases taken together. In other words, if the difference between the currents measured on two phases exceeds a threshold, then the fault tolerance strategy is implemented. More generally, the detection logic can take into account both types of comparison mentioned above, with thresholds determined for the application.

[0079] The fault tolerance strategy is implemented following the detection of an electrical fault. This fault tolerance strategy involves activating control function F2 first, taking priority over control function F1, in order to reduce the current load on the converter. Activating control function F2 causes the short-circuiting elements 10 of the symmetrization unit 8a to close. This makes external symmetrization operational via the short-circuiting elements and their series resistors. In other words, the fault tolerance strategy first applies external symmetrization by activating control function F2. This distributes the DC short-circuit current between the symmetrization branches and the converter 7a, thereby reducing the current load on the converter.

[0080] An internal symmetrization of the converter 7a can then be applied by activating the control function F1 of the switching arms of the converter 7a. That is to say, a slight time delay occurs between the activation of the control function F2 and that of the control function F1.

[0081] When function F l is activated, the arms of converter 7a are put into the protection configuration (internal symmetrization) described above, in which the switching cells 13, 15, 17 on the high pole side of the supply are all controlled to the open, non-conducting state; and the switching cells 14, 16, 18 on the low pole side are all controlled to the closed, conducting state, short-circuiting the phase outputs to the low pole of the supply.

[0082] The time lag between the activation of function F2 and then the activation of function F1 allows, when function F1 is activated to place the converter in a symmetrized configuration, a reduction in the current level in the "low" switching cells in the closed state 14, 16, 18. This time lag is less than a few milliseconds. In one embodiment, this time lag between the activation of function F2 and the activation of function F1 is on the order of a few microseconds.

[0083] In practice, this time lag between the activation of function F2 and function F1 results from a prioritization logic (first F2) and detection of current threshold condition(s).

[0084] In one embodiment, the control function F2 having been activated following the detection of an electrical fault, the fault tolerance strategy is configured to activate or not activate the control function F1 of converter 7a, depending on the phase current measurements.

[0085] In one embodiment, the fault tolerance strategy is such that if a current measurement in one phase shows a current level above a first threshold but below a second threshold, the function F1 may not be activated. In another variant, the current difference between the phase signals is compared pairwise. In this variant, if a current difference between two phase signals is above a first threshold but below a second threshold, the function F1 may not be activated. In this case, only the function F2 performs fault symmetrization.

[0086] Conversely, if the current measurement (or alternatively, the current difference) exceeds the second threshold, function F1 is activated. In this case, function F2, and then function F1, contribute to symmetrizing the fault. The first threshold can correspond to the detection threshold defined for detecting an electrical fault, particularly an asymmetric one, which is, by analogy, also the activation threshold for function F2.

[0087] In practice, the current detection threshold(s), particularly the first and second detection thresholds defining different activation conditions for functions F2 and F1, are predetermined according to the electrical machine and the application in question. They are defined in such a way as to ensure priority activation of function F2; and to ensure, following the activation of function F2, the activation of function F1 if necessary. Furthermore, the detection logic can combine the two detection logics indicated above, based on currents or their differences, with thresholds associated with each detection logic.

[0088] Thus, as indicated above, the tolerance strategy prioritizes the activation of control function F2 to close the three short circuits 10 of the symmetrizing element 8a, preventing a short circuit from destroying converter 7a. This minimizes the consequences of the short circuit. Activation of control function F2 takes priority because it acts on the short circuits 10, which are always operational components in such a situation. Therefore, function F2 must necessarily be activated more quickly than function F1, and the activation condition of function F2 must be independent of the activation condition of function F1.

[0089] As illustrated in Figure 2, the supervisory element 21, 21' in communication with the sensors 20, 20', therefore makes it possible to detect and manage the electrical failure and to control the functions F1 and F2 appropriately according to the defined fault tolerance strategy.

[0090] In one embodiment, the fault tolerance strategy can systematically apply external symmetrization driven by function F2 first, followed by internal symmetrization (function Fl). In particular, in such a case, a single current detection threshold can be defined. In another embodiment, the fault tolerance strategy systematically applies the external symmetrization function F2 first, and then activates or deactivates the internal symmetrization function Fl within the converter. In such a case, as explained previously, different thresholds can be defined, at least a first and a second threshold, to define at least one activation logic for internal symmetrization (function Fl).

[0091] Advantageously, the short-circuiters 10 are of the pyrotechnic action type which are characterized by a closing dynamic of less than 1 millisecond, equivalent to the static switching of a switching cell of the converter 7a, 7b.

[0092] The resistors 9 of the symmetrizing element 8a, 8b form a network of resistors 9, with an impedance lower than the equivalent impedance of the converter 7a, 7b as previously stated. As described above, in the fault symmetrization configuration, as soon as the short-circuiters 10 are closed by the control function F2 triggered by short-circuit current detection, the short-circuit current is directed to the symmetrization branches forming paths with a lower impedance than the internal impedance of the converter. This external symmetrization of the converter can be complemented by internal symmetrization of the converter, by placing the converter in the internal symmetrization configuration illustrated in Figure 3B, and then activating the control function F1.

[0093] Therefore, the symmetrization of the current via low impedance resistive branches connected to the phase outputs of the converter 7a, 7b, in combination with the symmetrization within the converter 7a, 7b itself, allows the stresses on the more fragile electronic components of the converter 7a, 7b to be released.

[0094] The choice of whether or not to activate the control function F1 following the control function F2 reflects in practice a logic of monitoring and detection of phase currents adapted to the system under consideration.

[0095] According to the embodiment illustrated in the figures, the mechatronic system 1 comprises two segregated and independent electromechanical channels, thus providing internal redundancy of its components. Each electromechanical channel is capable of driving the electric motor via an associated three-phase star connection, the two three-phase stars of the electric motor being magnetically independent. Each channel includes an associated power supply and, from upstream to downstream, an energy storage device (5a, 5b), a protection component (6a, 6b), a converter (7a, 7b), and an associated three-phase star connection of the electric motor. The mechatronic system (1) is thus designed to ensure the redundancy, segregation, and independence of the electromechanical channels and the symmetrization of electrical faults, so as to ensure continuity of service of the mechatronic system.It is entirely possible for the mechatronic system 1 to comprise more than two segregated and independent electromechanical channels, the varying number of redundancies being a compromise between the permissible increase in system mass and the desired level of safety. The symmetrization device 8a, 8b is adapted to this redundancy, with one branch per phase output signal or per phase, and for each electromechanical channel.

[0096] The proposed mechatronic system 1, including a hardware strategy as described, makes it possible to improve the symmetrization of asymmetric electrical failures, while ensuring continuity of aircraft services via non-failing channels not affected by the failure.

Claims

DEMANDS 1. A mechatronic system (1) tolerant to a single electrical failure of a hybrid-electric or electric aircraft engine, said mechatronic system (1) comprising an electric engine (2) and at least two electronic circuits (3a, 3b) each comprising at least one energy storage unit (5a, 5b), at least one converter (7a, 7b) positioned downstream of the energy storage unit (5a, 5b), and a power supply, the electric engine (2) being connected to the aircraft engine and the electronic circuits (3a, 3b), characterized in that the electronic circuits (3a, 3b) each comprise at least one electrical failure symmetrization element (8a, 8b) comprising at least one phase signal symmetrization branch (a, b, c, a', b', c') at the output of the converter (7a, 7b) connected to an associated phase (A, B, C, A'). , B', C') of the electrical machine (2), the electrical machine (2) comprising at least two three-phase stars (4a,4b) magnetically independent, each symmetrizing device (8a, 8b) constituting a material element for current diversion and dissipation, configured to allow symmetrization of an electrical failure external to the converter (7a, 7b), and each assembly of an electronic circuit (3a, 3b), its power supply and the associated star connection (4a, 4b) forming a segregated electromechanical channel independent of the other electromechanical channel(s), the mechatronic system (1) being designed to ensure redundancy, segregation, independence of the electromechanical channels and symmetrization of electrical failures, in order to ensure continuity of service of said mechatronic system.

2. System (1) according to claim 1, wherein each symmetrization branch includes a short-circuiter (10).

3. System (1) according to claim 2, wherein the short-circuiter (10) is pyrotechnically acted (10).

4. System (1) according to any one of claims 2 to 3, wherein each symmetrization branch further comprises a resistor (9) in series with the short-circuiter (10) of said branch.

5. System (1) according to any one of claims 2 to 4, wherein a control function (F2) of the symmetrizing element (8a, 8b), is configured to simultaneously control the closing of the short circuiter (10) of each symmetrization branch as a function of a current measurement on each phase signal.

6. System (1) according to claim 5, comprising a supervisory element (21, 21') configured to apply a fault tolerance strategy comprising detection of an electrical fault based on the measurement of phase signal currents and symmetrization of a detected electrical fault by activation of the control function (F2) of the symmetrization element (8a, 8b).

7. System (1) according to claim 6, wherein the fault tolerance strategy is such that the symmetrization of the detected electrical fault includes the activation of the control function (F2) of the symmetrizing element prior to an internal symmetrization control function (F1) of the converter arms (7a, 7b).

8. System (1) according to claim 7, wherein the fault tolerance strategy further includes an activation condition for the control function (Fl) of internal symmetrization of the converter arms (7a, 7b), such that said control function (Fl) is or is not activated as a function of a current measurement on each phase signal.

9. Motor comprising a mechatronic system (1) according to any one of claims 1 to 8.

10. Aircraft comprising a mechatronic system (1) according to any one of claims 1 to 8 or at least one engine according to claim 9.

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