Method for monitoring and protecting an electrical hybridization system

Abstract

The invention relates to a method for monitoring and protecting an electrical hybridization system for an aircraft (400), the system comprising a first reversible electric machine (100), a second reversible electric machine (200), and two electrical power distribution units (330, 340), each electrical power distribution unit (330, 340) comprising a high-voltage busbar (335, 345), a first controlled switch, and a second controlled switch (334, 344), the method comprising, for each controlled switch: - determining the operating mode of the electric machine coupled to the controlled switch; - measuring the current (Imes1) at the input of the controlled switch; and - a step of opening the controlled switch if both: - the measured current (Imes1) is in a direction opposite to the direction of the expected nominal current; and - the value of the measured current (Imes1) is higher than at least one current threshold (Iseuil1).

Description

Description Title of the invention: Method for monitoring and protecting an electrical hybridization system Technical Field

[0001] The present invention relates to the field of protection systems for electrical distribution networks in electrically or hybrid-powered aircraft and more particularly to a method for monitoring and protecting an electrical hybridization system. Previous technique

[0002] 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 operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively contributing to the fight against climate change for several years now.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order 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 impacts, with the aim of improving the energy efficiency of aircraft.

[0004] The Applicant works in research and development on new generations of engines, the lightening of devices, in particular through the materials used and lighter on-board equipment, electrical technologies to ensure propulsion, and electric biofuels.

[0005] Traditional protection principles for electrical networks and hybrid systems rely on simple and mostly passive devices. These protections primarily safeguard the electrical installation itself, not the individual equipment. This protection is based on the thermal behavior of the cables and, very locally, on a differential mode to detect cable disconnections. In addition to distribution protection, generators also have protection mechanisms that monitor the thermal behavior of the generator windings and the dynamic voltage behavior to ensure they remain within acceptable limits for consumers.

[0006] However, existing monitoring and protection methods for hybrid electric systems do not account for the reversibility of the electrical machines within these systems—that is, their ability to operate in generator mode or motor mode. When a malfunction is detected, isolating the components responsible for the malfunction generally requires isolating other components as well. This can jeopardize the operation of the entire hybrid electric system.

[0007] Thus, there is a real need to monitor and protect an electrical hybridization system without the drawbacks inherent in the aforementioned known processes.

[0008] A method for monitoring and protecting an electrical hybridization system is known in the prior art, for example described in document EP3796502. Description of the invention

[0009] To this end, the invention proposes a method for monitoring and protecting an electrical hybrid system for an aircraft. The system comprises a first reversible electric machine intended to be connected to a low-pressure shaft, a second reversible electric machine intended to be connected to a high-pressure shaft, and two electrical power distribution units. Each electric machine comprises a first winding associated with a first AC / DC converter and a second winding associated with a second converter. AC / DC, and each electrical power distribution unit includes a high-voltage distribution busbar, a first controlled switch electrically connecting the high-voltage distribution busbar to the first reversible electrical machine via its first AC / DC converter, a second controlled switch electrically connecting the high-voltage distribution busbar to the second reversible electrical machine via its second AC / DC converter.

[0010] According to a general characteristic of the method according to the invention, the method comprises, for each controlled switch: - a determination of the operating mode of the electrical machine coupled to the controlled switch, choosing between a motor mode and a generator mode, - a measurement of the current at the input of the controlled switch, and - a step of opening the controlled switch if, at the same time: - the measured current is in the opposite direction to the expected nominal current in the specified operating mode of the electrical machine, and - the measured current value is greater than at least a current threshold, the value of the current threshold depending on the operating mode of the electrical machine.

[0011] Such a process makes it possible to detect a malfunction in the electric hybrid system quickly and accurately, and to isolate the faulty part.

[0012] To achieve this, an acceptable current threshold is defined beforehand for each component or element of the electrical hybridization system. This acceptable current threshold for each component or element is determined based on the properties of the materials constituting the component. This acceptable current threshold can be determined based on the position of the components within the hybridization system and the current rating associated with the components or elements.

[0013] The current threshold is then set prior to the process, based on the various acceptable current thresholds. Detecting a current exceeding the threshold indicates the presence of a fault in the electric hybrid system. In such a case, it is best to locate the fault in order to isolate only the system components affected by the malfunction. This This prevents the overall functioning of the electric hybrid system from being jeopardized.

[0014] A specific direction of the rated current is assigned to each operating mode of the electrical machines in the hybrid electrical system. Determining the operating mode of the electrical machine allows us to determine the expected current direction in the absence of a fault. In generator mode, the electrical machine delivers current, while in motor mode, it consumes current supplied to it at the input.

[0015] Detecting a current direction opposite to the nominal current direction indicates the presence of a fault and allows it to be located.

[0016] This allows for the isolation of only the parts affected by the malfunction, preventing damage to other components of the electric hybrid system. Electrical isolation is achieved by opening the relevant controlled switch. This process thus isolates the faulty components and the branch of the hybrid system affected by the malfunction, while preventing the propagation of faults within the entire electric hybrid system.

[0017] Furthermore, such a process allows for maximum availability of the other elements of the electric hybrid system.

[0018] According to a particular feature of the process, in the step of opening the controlled switch, the value of the measured current can be compared to a first current threshold above which the controlled switch is opened without delay, and then to a second current threshold below which the controlled switch remains closed, the value of the first current threshold being greater than the value of the second current threshold.

[0019] Comparing the current value at two different thresholds allows us to define three different protection regimes: the first below which no protection is needed, the second above which protection is immediate, and the third where protection can be adapted according to parameters.

[0020] An immediate opening of the controlled switch means that there is no added time delay between the comparison step and the opening step. In electronic and physical terms, there is a small time lag. between the start of the comparison and the complete opening of the controlled switch. This small time lag is due to the clarification time, the detection time, the command processing time, and the physical opening time of the component.

[0021] According to a particular feature of the process, when the measured current value is between the first current threshold and the second current threshold, the step of opening the controlled switch may also include: - a determination of a confirmation time interval dependent on the value of the measured current, - successive additional measurements of the input current of the controlled switch during the confirmation time interval, - a comparison of a cumulative energy value to a tolerated absorbed energy threshold, the cumulative energy value being obtained by integrating the current measurement and successive complementary current measurements and - an opening of the controlled switch if the value of the cumulative energy is greater than the tolerated absorbed energy threshold.

[0022] This enables even more precise and effective monitoring and protection of the electrical hybrid system. Indeed, taking several complementary and successive measurements of the input current to the controlled switch during the confirmation time interval allows for simple sampling of the input current. Comparing each current measurement to the first current threshold enables even more precise detection of faults and more effective triggering of the controlled switch.

[0023] Depending on a particular characteristic, the process may further include, for each controlled switch, - a measurement of the input voltage of the controlled switch, - the step of opening the controlled switch being carried out only if, in addition, the measured voltage is less than a voltage threshold.

[0024] These additional steps and conditions for opening the system help to confirm the presence of a malfunction. of electrical hybridization before triggering the opening. Indeed, the presence of a measured voltage below a voltage threshold confirms the presence of a short circuit within the electrical hybridization system.

[0025] Depending on a particular characteristic of the process, each current measurement can be associated with a voltage measurement.

[0026] According to another particular characteristic, each controlled switch may have a first normally open auxiliary contact and a second normally closed auxiliary contact; the method may further include, for each controlled switch that has been opened, a closing step if both: - The first auxiliary contact is open - the second auxiliary contact is closed and, - the current measured at the input of the controlled switch is zero.

[0027] This procedure confirms the absence of faults in the system and verifies the status of the controlled switch before reconnecting it. This allows for the safe reconnection of the controlled switch.

[0028] In another aspect of the invention, an electrical hybridization system for an aircraft is proposed, the system comprising a first reversible electric machine intended to be connected to a low-pressure shaft, a second reversible electric machine intended to be connected to a high-pressure shaft, two electrical power distribution units, and a control board, each reversible electric machine comprising a first winding associated with a first AC / DC converter and a second winding associated with a second AC / DC converter, and each electrical power distribution unit comprising a high-voltage distribution busbar, a first controlled switch electrically connecting the high-voltage distribution busbar to the first reversible electric machine via its first AC / DC converter,a second controlled switch electrically connecting the high-voltage distribution busbar to the second reversible electric machine via its second, AC / DC converter. The system is characterized in that the control board is configured to implement the process as defined above. Brief description of the drawings

[0029] Other features and advantages of the present invention will become apparent from the description given below, with reference to the attached drawings which illustrate an example of an embodiment without any limiting character.

[0030] [Fig. 1] Figure 1 illustrates a first example of an electric hybridization system according to the invention,

[0031] [Fig. 2] Figure 2 illustrates the flowchart of the steps of a first embodiment of a process according to the invention,

[0032] [Fig. 3] Figure 3 illustrates the flowchart of the steps of a second embodiment of a process according to the invention,

[0033] [Fig. 4] Figure 4 illustrates two curves of current threshold values ​​and the corresponding confirmation time for each value for the process in Figure 3. Description of the implementation methods

[0034] The invention applies generally to the protection of electrical distribution networks in aircraft and, more particularly, to that of aircraft with electric or hybrid propulsion.

[0035] Figure 1 illustrates an example of an electric hybridization system according to the invention.

[0036] The electric hybridization system 400 includes a first electric machine 100, a second electric machine 200, several AC / DC converters 130, 140, 230, 240, a first electrical power distribution unit 330, a second electrical power distribution unit 340, and a plurality of local loads 350, 351, 352, 353, 354, 355.

[0037] The first electric machine 100 and the second electric machine 200 can each be rotating electric machines. More specifically, electric machines 100 and 200 can each be electric machines Rotating PMG (Permanent Magnet Generator) type generators, also known as permanent magnet generators. The first electric machine, 100, is intended to be connected to a low-pressure shaft of an aircraft turbomachine not shown in Figure 1. The second electric machine, 200, is intended to be connected to a high-pressure shaft of a turbomachine not shown in Figure 1.

[0038] The first electric machine 100 comprises a first winding 110 and a second winding 120. The second electric machine 200 comprises a first winding 210 and a second winding 220. Windings 110, 120, 210, and 220 are stator windings. The number of windings in each of the machines 100 and 200 is not a limitation of the invention. According to an embodiment other than the one illustrated, each of the electric machines may comprise more than two windings.

[0039] The first winding 110 of the first electric machine 100 is electrically connected to a first converter 130. The second winding 120 of the first electric machine 100 is electrically connected to a second converter 140. The first winding 210 of the second electric machine 200 is electrically connected to a first converter 230. The second winding 220 of the second electric machine 200 is electrically connected to a second converter 240.

[0040] The 330 and 340 electrical power distribution units are also known as PDMU, which stands for Power Distribution Management Unit.

[0041] A control card 390 can be placed in the first electrical power distribution unit 330 and / or in the second electrical power distribution unit 340. This control card 390 is configured to control the protection elements of the electrical hybridization system 400.

[0042] The first electrical power distribution unit 330 further comprises a high-voltage distribution busbar 335, a first switch 333, a second switch 334, a third switch 336, and several fourth switches 338. The second electrical power distribution unit 340 it also includes a high-voltage distribution bar 345, a first switch 343, a second switch 344, a third switch 346 and several fourth switches 348.

[0043] Each of the controlled switches 333 to 338 or a part thereof, and 343 to 348 may be electromechanical controlled switches or electronic controlled switches.

[0044] When the controlled switches are electromechanical or electronic controlled switches, they can be in a bipolar configuration in the 400 hybrid system.

[0045] The number of high-voltage distribution bars is not a limitation of the invention.

[0046] According to a variant, each of the first electrical power distribution unit 330 and second electrical power distribution unit 340 can include a first positive high voltage distribution bar and a second negative high voltage distribution bar.

[0047] According to yet another variant, each of the first electrical power distribution unit 330 and second electrical power distribution unit 340 can include more than two high-voltage distribution bars.

[0048] The first controlled switch 333 of the first electrical power distribution unit 330 electrically connects the first electrical machine 100 to the high-voltage busbar 335 of the first electrical power distribution unit 330, via the first AC / DC converter 130 connected to the first electrical machine 100. The first controlled switch 333 is connected between a first input 331 of the first electrical power distribution unit 330 and its high-voltage busbar 335, the first input 331 of the first electrical power distribution unit 330 being connected to the first electrical machine 100 via the first AC / DC converter 130 of the first electrical machine 100.

[0049] The second controlled switch 334 of the first electrical power distribution unit 330 electrically connects the second electric machine 200 to the high-voltage busbar 335 of the first electrical power distribution unit 330, via the first AC / DC converter 230 connected to the second electric machine 200. The second controlled switch 334 is connected between a second input 332 of the first electrical power distribution unit 330 and its high-voltage busbar 335, the second input 332 of the first electrical power distribution unit 330 being connected to the second electric machine 200 via the first AC / DC converter 230 of the second electric machine 200.

[0050] The first controlled switch 343 of the second electrical power distribution unit 340 electrically connects the first electric machine 100 to the high-voltage busbar 345 of the second electrical power distribution unit 340, via the second AC / DC converter 140 connected to the first electric machine 100. The first controlled switch 343 is connected between a first input 341 of the second electrical power distribution unit 340 and its high-voltage busbar 345, the first input 341 of the second electrical power distribution unit 340 being connected to the first electric machine 100 via the second AC / DC converter 140 of the first electric machine 100.

[0051] The second controlled switch 344 of the second electrical power distribution unit 340 electrically connects the second electric machine 200 to the high-voltage busbar 345 of the second electrical power distribution unit 340, via the second AC / DC converter 240 connected to the second electric machine 200. The second controlled switch 344 connects a second input 342 of the second electrical power distribution unit 340 and its high-voltage busbar 345, the second input 342 of the second electrical power distribution unit 340 being connected to the second electric machine 200 via the second AC / DC converter 240 of the second electric machine 200.

[0052] The first electrical power distribution unit 330 has a first output 337 intended to be connected to the aircraft's electrical network. And, the second electrical power distribution unit 340 has a first output 347 intended to be connected to the aircraft's electrical network.

[0053] The third controlled switch 336 of the first electrical power distribution unit 330 electrically connects the high-voltage distribution busbar 335 of the first electrical power distribution unit 330 to its first output 337, which is intended to be connected to the aircraft's electrical network. The third controlled switch 346 of the second electrical power distribution unit 340 electrically connects the high-voltage distribution busbar 345 of the second electrical power distribution unit 340 to its first output 347, which is intended to be connected to the aircraft's electrical network.

[0054] Local loads 350 to 355 may include aircraft components other than those powered by the aircraft's electrical system. The fourth controlled switches 338 of the first electrical power distribution unit 330 connect the high-voltage distribution busbar 335 of the first electrical power distribution unit 330 to second outputs 339 intended to be connected to local loads 350, 351, and 352.

[0055] The fourth controlled switches 348 of the second electrical power distribution unit 340 connect the high voltage distribution busbar 345 of the second electrical power distribution unit 340 to second outputs 349 intended to be connected to local loads 353, 354 and 355.

[0056] The 400 electric hybrid system further includes sensors 391 to 398, as illustrated in Figure 1. In the example shown in Figure 1, each sensor 391 to 398 is mounted at the input of one of the controlled switches 333 to 338, and 343 to 348, respectively. These sensors 391 to 398 allow for the measurement of several parameters at the input of each controlled switch 333 to 338, and 343 to 348. These parameters may include current, voltage, temperature, the presence of an electric arc, and resistance. electrical. The number of sensors and their locations are not limiting to the invention.

[0057] Sensors 391 through 398 may include at least one current sensor and / or at least one voltage measurement board, and / or at least one ohmmeter, and / or at least one temperature sensor. The current sensor may include an ammeter. The voltage measurement board may include a voltmeter.

[0058] According to the invention, the electrical hybridization system 400 includes a current sensor and a voltage measurement card at the input of the first and second controlled switches of each electrical power distribution unit 330 and 340.

[0059] The current sensor allows, in particular, the direction of the nominal current to be set for each operating mode of electrical machines.

[0060] In addition, each of the controlled switches includes a first normally open auxiliary contact and a second normally closed auxiliary contact, not shown. These auxiliary contacts allow the position of the controlled switch to be verified.

[0061] When the controlled switch is open, the first normally open auxiliary contact is open and the second normally closed auxiliary contact is closed

[0062] Conversely, when the controlled switch is closed, the first normally open auxiliary contact is closed and the second normally closed auxiliary contact is open.

[0063] When the controlled switch is in an intermediate position between the open position and the closed position, the first auxiliary contact and the second auxiliary contact are open.

[0064] Figure 2 illustrates a first example of the implementation of the process according to the invention implemented by the control card 390 to control the protection elements of the electric hybridization system 400. The process is designed to protect and monitor the electric hybridization system described above.

[0065] In the first step, El, the operating mode of each electrical machine 100, 200 is determined. Indeed, each of the electrical machines 100 and 200 is a reversible machine and can therefore operate in motor mode or generator mode. This step determines the direction of the expected input current to each of the controlled switches 333, 334, 343, 344, for a given operating mode of the electrical machine, when no fault is present.

[0066] When the first electric machine 100 is operating in motor mode, a source supplies electrical power to the first distribution unit 330 and / or the second distribution unit 340. In one variant, the source supplying power may be the aircraft's electrical network or the second electric machine 200.

[0067] The electrical energy received by the first electrical power distribution unit 330 and / or the second electrical power distribution unit 340 is then transmitted to the first electrical machine 100. In other words, the first electrical machine 100 is powered either by the electrical energy supplied by the first electrical power distribution unit 330, or by the electrical energy supplied by the second electrical power distribution unit 340, or by the electrical energy supplied by both electrical power distribution units 330 and 340. The electrical energy received by the first electrical machine 100 will then be transformed by the first winding 110 and / or the second winding 120 into mechanical energy to drive the low-pressure shaft.

[0068] When the second electric machine 200 operates in motor mode, a source supplies electrical energy to the first distribution unit 330 and / or the second distribution unit 340. The electrical energy received by the first electrical power distribution unit 330 and / or the second electrical power distribution unit 340 is then transmitted to the second electric machine 200. In other words, the second electric machine 200 is powered either by the electrical energy supplied by the first electrical power distribution unit 330, or by the electrical energy supplied by the second electrical power distribution unit 340, or by the electrical energy supplied by the two electrical power distribution units 330 and 340. The electrical energy received by the second electrical machine 200 will then be transformed by the first winding 210 and / or the second winding 220 into mechanical energy to drive the high pressure shaft.

[0069] The energy source supplying electrical energy to the first distribution unit 330 and / or the second distribution unit 340 can be, for example, a battery, connected to the first output 337 of the first distribution unit 330 and / or the first output 347 of the second distribution unit 340.

[0070] In one variant, the first distribution unit 330 can be powered by a separate energy source from that powering the second distribution unit 340.

[0071] When the first electric machine 100 operates in generator mode, the mechanical energy from the low-pressure shaft is converted into electrical energy by the first winding 110 and / or the second winding 120 of the first electric machine 100. In other words, the mechanical energy from the low-pressure shaft can be converted into electrical energy either by the first winding 110, or by the second winding 120, or by both windings 110 and 120. The electrical current generated during this conversion is then transmitted by the first electric machine 100 to the first electrical power distribution unit 330 and / or to the second electrical power distribution unit 340.

[0072] When the second electric machine 200 operates in generator mode, the mechanical energy from the high-pressure shaft is converted into electrical energy by the first winding 210 and / or the second winding 220 of the second electric machine 200. In other words, the mechanical energy from the high-pressure shaft can be converted into electrical energy either by the first winding 210, or by the second winding 220, or by both windings 210 and 220. The electrical current generated during this conversion is then transmitted by the second electric machine 200 to the first electrical power distribution unit 330 and / or to the second electrical power distribution unit 340.

[0073] When the first electric machine 100 operates in generator mode, the current measured by the current sensors 391 and 395 at the input of the first controlled switches 333 and 343 is positive. When the second electric machine 200 operates in generator mode, the current measured by the current sensors 392 and 396 at the input of the second controlled switches 334 and 344 is positive. The rated current in generator mode is therefore positive. For example, when the first electric machine 100 operates in generator mode, a positive current is expected at the input of the controlled switch 333. The same is true for the current at the input of the controlled switch 343 when the second electric machine 200 operates in generator mode.

[0074] Conversely, when the first electric machine 100 operates in motor mode, the current measured by the current sensors 391 and 395 at the input of the first switching components 333 and 343 is negative. When the second electric machine 200 operates in motor mode, the current measured by the current sensors 392 and 396 at the input of the first controlled switches 334 and 344 is negative. The rated current in motor mode is therefore a negative current.

[0075] The direction of the nominal current assigned to each operating mode is not limiting to the invention.

[0076] According to one variant, the first electric machine 100 or the second electric machine 200 can operate in motor mode and be powered by the other electric machine. In this case, the other machine operates in generator mode.

[0077] Once the operating mode of the electrical machine associated with the controlled switch has been determined, the process is followed by a step E2 of measuring the current Imesi at the input of the controlled switch by the current sensors 391 and 395 for each distribution unit 330 and 340, as illustrated in Figure 2.

[0078] When the electrical hybridization system 400 includes sensors mounted at the input of the controlled switches, the current can be measured at the sensors. In the example shown in Figure 1, the current measurement step E2 (Imesi) can be performed at sensors 391 to 398. For example, if the input current of the controlled switch 333 needs to be measured, the current can be measured at sensor 391. If the electrical hybridization system 400 includes a positive HVDC busbar and a negative HVDC busbar, a current sensor can be used for each HVDC busbar, thus measuring the current for each pole.

[0079] Alternatively, when the electrical hybridization system includes sensors mounted at the input and output of the controlled switches, the current measurement, during step E2, can be carried out at the input and output of the controlled switch.

[0080] Current measurements are taken during each of the aircraft's operating phases, namely during the distribution phase, the start-up phase, and the engine assist phase.

[0081] In a distribution phase, the first electric machine 100 and the second electric machine 200 operate in generator mode.

[0082] During the startup phase, the first electric machine 100 or the second electric machine 200 operates in motor mode. The electric machine operating in motor mode can be assisted by the other electric machine during startup.

[0083] During a motor assistance phase, the first electric machine 100 or the second electric machine 200 operates in generator mode and powers the other electric machine.

[0084] In step E3, following step E2 of current measurement, the direction of the measured current is compared to the direction of the nominal current expected in the operating mode determined during step El.

[0085] The threshold can also be defined according to the position of the controlled switch in the hybridization system, and the type of protection provided in the The hybridization system and the component's rating. The protection provided in the hybridization system can be, for example, source protection, load protection, or cable protection.

[0086] As illustrated in Figure 2, when the direction of the measured current corresponds to the direction of the nominal current, the controlled switch is held in the closed position in step E6, unless the value of the measured current Imesi is greater than a current threshold læuii, in which case the controlled switch is opened in step E4. Such a threshold is defined beforehand according to the electrical properties of the materials constituting the different elements of the electrical hybridization system.

[0087] In one variation, the threshold can be defined using a thermocouple. In this case, the thermocouple is installed near the controlled switch, and the current is then gradually increased. The increase in current generates a rise in temperature. A maximum temperature is determined during the current increase. This temperature ensures the proper operation of the controlled switch. The current associated with the predefined maximum temperature that must not be exceeded constitutes the current threshold.

[0088] Conversely, if the direction of the measured current is opposite to the direction of the nominal current, the controlled switch is opened in step E4. In a comparison step E7, the absolute value of the measured current |Imesi| is compared to an absolute value of a current threshold |Iseuiii|, as illustrated in Figure 2. This comparison step E7 is optional. The controlled switch is opened in step E4 only if the absolute value of the measured current is greater than or equal to the absolute value of the current threshold. This comparison step helps prevent false detections of a change in current direction. Otherwise, the controlled switch is held in the closed position in step E6.

[0089] The fact that the measured current (Imesi) has a current direction opposite to the nominal current direction indicates the presence of a fault in the electrical hybrid system. The fault will then be located upstream of where the measurement was carried out; either in this case, upstream of the input of the controlled switch.

[0090] For example, when the first machine 100 is operating in generator mode, a current threshold can be set at -700A. A positive direction of the rated current is expected in generator mode. In this case, when a current of -800A is measured at the input of the controlled switch 333, the controlled switch 333 is opened in step E4.

[0091] Conversely, if a current of +500A is measured at the input of the controlled switch 333, the controlled switch 333 remains in the closed position in step E5. On the other hand, if a current of +800A is measured at the input of the controlled switch 333, the controlled switch 333 will be open.

[0092] Figure 3 illustrates a second example of a method according to the invention.

[0093] In the example shown in Figure 3, the process comprises the same steps E1, E2, E3 as in the process shown in Figure 2. When the direction of the current measured in step E2 is opposite to the direction of the nominal current, the controlled switch is opened in step E4. The comparison step E7 of the absolute value of the measured current |Imesi| to an absolute value of a current threshold |Iseuiii| described previously may be present, as shown in Figure 3.

[0094] Instead of the comparison step E5, when the direction of the measured current is nominal, the process includes a first comparison E51 of the measured current value Imesi to the value of a first current threshold Iseuiimax, and a second comparison E52 of the measured current value Imesi to the value of a second current threshold Iseuiimin. The value of the first current threshold Iseuiimax is greater than the value of the second current threshold Iseuiimin.

[0095] When the direction of the measured current corresponds to the direction of the expected nominal current, the value of the measured current Imesi is compared to the value of the first current threshold Iseuiimax and to the value of the second current threshold Iseuiimin, in steps E51 and E52.

[0096] If the measured current value Imesi is greater than or equal to the first current threshold Iseuiimax, the controlled switch is opened in step E4.

[0097] When the measured current value Imesi is less than the value of the first current threshold Iseuiimax and is greater than or equal to the value of the second current threshold Iseuiimin, the controlled switch is held in the closed position in a step E6, as illustrated in Figure 4.

[0098] If the measured current value Imesi is greater than the value of the second current threshold Iseuiimin and less than the value of the first current threshold Iseuiimax, the method further includes a step E8 for determining a confirmation time interval. In other words, the step of determining a confirmation time interval is carried out if the measured current value Imesi lies between the value of the second current threshold Iseuiimin and the value of the first current threshold Iseuiimax.

[0099] The value of the confirmation time depends on the value of the measured current Imesi.

[0100] Once the confirmation time has been determined in step E8, several successive complementary measurements of the input current of the controlled switch are carried out during the confirmation time, in a step E9.

[0101] Depending on a particular characteristic, the confirmation time can range from 0.5 to 100 seconds.

[0102] The current measured during each successive complementary measurement is integrated over the confirmation period. This integration corresponds to a cumulative energy Ecumul.

[0103] A threshold of tolerated absorbed energy Eseuil is defined beforehand and corresponds to the maximum amount of current that the component associated with the switch can absorb over the confirmation time.

[0104] The cumulative energy Ecumul is then compared to the tolerated absorbed energy threshold Eseuil. When the value of the cumulative energy Ecumul is above the tolerated absorbed energy threshold Eseuil, the controlled switch is opened, in step E4, as illustrated in figure 4.

[0105] Conversely, if the value of the cumulative energy Ecumul is less than or equal to the tolerated absorbed energy threshold Eseuil, the controlled switch is held in the closed position in a step E6.

[0106] The figure illustrates two curves of current threshold values ​​and the corresponding confirmation time for each value for the process illustrated in Figure 3.

[0107] Curve B (dotted line) illustrates a monitoring and protection curve obtained for an electrical machine operating in motor mode. The direction of the expected rated current in motor mode is negative.

[0108] Curve A, shown as a continuous line, illustrates a monitoring and protection curve obtained for the same electrical machine operating in generator mode. The direction of the expected rated current in generator mode is positive.

[0109] For example, when the electrical machine is operating in generator mode, a second Iseuiimin threshold is set at +200A and a first Iseuiimax threshold is set at +700A.

[0110] When a measured current (Imesi) of +600A is detected, the controlled switch is held in the closed position during step E6. This is because the direction of the measured current (Imesi) corresponds to the expected nominal direction in generator mode, i.e., a positive current, and it is below the first threshold of +700A. [YES] In another example, when a current Imesi equal to -150A is measured, the controlled switch is open in step E4. The direction of the measured current Imesi is opposite to the nominal direction expected in generator mode, because it is a negative current.

[0112] In a case where a measured current Imesi equal to +400A is recorded, the direction of the measured current is compared to the expected nominal direction in generator mode. Here, the measured current Imesi is positive, and therefore its direction corresponds to the expected nominal direction in generator mode. Next, the value of the measured current Imesi is compared to the value of the first current threshold Iseuiimax. The current value The measured current Imesi is also compared to the value of the second current threshold Iseuiimin. The value of +400A of the measured current Imesi is greater than the value of +200A of the second current threshold Iseuiimin and less than the value of +700A of the first current threshold Iseuiimax.

[0113] The comparison of the measured current value Imesi with the value of the first current threshold Iseuiimax is carried out before the comparison of the measured current value Imesi with the value of the second current threshold Iseuiimin.

[0114] In one variant, the comparison of the measured current value Imesi with the value of the first current threshold Iseuiimax and with the value of the second current threshold Iseuiimin is carried out simultaneously.

[0115] The measured current value of +400A, Imesi, lies between the value of the first threshold, Iseuiimax, and the value of the second threshold, Iseuiimin. In this case, a confirmation time, dependent on the measured current value, Imesi, is determined during step E8. The confirmation time corresponding to a measured current of Imesi = +400A is 3 seconds, as illustrated in Figure 4.

[0116] Successive additional measurements of the input current to the controlled switch are taken during the confirmation period, in step E9. For a measured current Imesi = +400 A, successive additional current measurements are taken for 3 seconds. This allows for current sampling and more precise confirmation of the presence of a fault before triggering the opening of the controlled switch.

[0117] For the measured current Imesi = +400A, when the cumulative energy value Ecumul obtained after integrating successive complementary current measurements exceeds the tolerated absorbed energy threshold Eseuil, equal to 200A after 3 seconds, the controlled switch is opened. Otherwise, the controlled switch remains closed during step E3, as illustrated in Figure 4.

[0118] For example, when the electric machine is operating in motor mode, a second Iseuiimin threshold can be set at -250A and a first Iseuiimax threshold can be set at -700A.

[0119] For example, when a measured current Imesi of -150A is observed, the controlled switch remains closed during step E6. This is because the direction of the measured current Imesi corresponds to the expected nominal direction in motor mode, as it is a positive current. Therefore, in motor mode, a current Imesi of -150A will not cause the controlled switch to open. Such a current is constantly above curve B.

[0120] When a current Imesi equal to -800A is measured, the controlled switch is opened, in a step E4. Indeed, the direction of the measured current Imesi corresponds to the nominal direction expected in motor mode and is greater than the value of the first threshold equal to -700A.

[0121] When a current Imesi=-300A is measured, a confirmation time is determined in step E8. Several successive complementary measurements of the input current of the controlled switch are then carried out during the confirmation time, in a step E9.

[0122] The sum of the current values ​​measured during each of the successive supplementary measurements taken during the confirmation period yields the cumulative energy Ecumul. When the cumulative energy value Ecumul exceeds the tolerated absorbed energy threshold Eseuil, here equal to -300A after a maximum of 4 seconds, the controlled switch is opened.

[0123] According to a particular feature, the method may further include, for each controlled switch, measuring the input voltage Vmesi of the controlled switch. In this case, the measured voltage value is compared to the value of a voltage threshold Væuiii.

[0124] Measuring such a voltage confirms the presence of a fault in the electric hybrid system.

[0125] For the example illustrated in Figure 2, the opening E4 of the controlled switch can be achieved if the direction of the measured current is opposite to the direction of the nominal current, the value of the measured current Imesi is greater than or equal to the value of the current threshold Imesi and the value of the measured voltage Vmesi is less than the value of the voltage threshold Vseuiii.

[0126] For the process illustrated in Figure 3, when the measured current value Imesi is greater than the value of the second current threshold Iseuiimin and greater than or equal to the value of the second threshold Iseuiimax, the controlled switch E4 will open if both of the following conditions are met: - the direction of the measured current is opposite to the direction of the nominal current, and - that the measured voltage value Vmesi is less than the voltage threshold value Vseuiii.

[0127] For the process illustrated in Figure 3, when the measured current value Imesi is between the value of the second threshold Iseuiimin and the value of the first threshold Iseuiimax, the controlled switch will open if both of the following conditions are met: - the direction of the measured current is opposite to the direction of the nominal current. - the value of the cumulative energy Ecumul is greater than the tolerated absorbed energy threshold Eseuil, and, - that the measured voltage value Vmesi is less than the voltage threshold value Vseuiii.

[0128] Each current measurement can be associated with a voltage measurement. For example, during a short circuit the measured current will be greater than the first Iseuiimax threshold, and it will be accompanied by a voltage drop.

[0129] When the controlled switches of the electrical hybrid system have a first normally open auxiliary contact and a second normally closed auxiliary contact, the procedure may further include, for each controlled switch, a closing step. This closing step is performed once the fault in the electrical hybrid system has been resolved. Before initiating the closing, it is verified that the controlled switch is in an open state, that is, that the first normally open auxiliary contact is indeed open, and that the second normally closed auxiliary contact is indeed closed.

[0130] In other words, this closing step is performed if the following conditions are all met: the first auxiliary contact is open, the second auxiliary contact is closed, and there is no current at the input of the controlled switch. In other words, if the measured current Imes at the input of the switch is zero.

[0131] The presence of the first auxiliary contact in the closed position and the second auxiliary contact in the open position allows for an initial verification that the controlled switch is in the open position. The presence of a zero current (Imes) measured at the input of the controlled switch corresponds to a second verification that the controlled switch is in the open position.

[0132] Thus, it is possible to safely trigger the closing of the controlled switch.

Claims

Demands

1. A method for monitoring and protecting an electrical hybrid system for an aircraft (400), the system comprising a first reversible electric machine (100) for connection to a low-pressure shaft, a second reversible electric machine (200) for connection to a high-pressure shaft, and two electrical power distribution units (330, 340), each reversible electric machine (100, 200) comprising a first winding (110, 210) associated with a first AC / DC converter (130, 230) and a second winding (120, 220) associated with a second AC / DC converter (140, 240), and each electrical power distribution unit (330, 340) comprising a high-voltage distribution busbar (335, 345), a first controlled switch (333, 343) electrically connecting the high-voltage distribution busbar (335, 345) to the first reversible electric machine (100) via its first AC / DC converter (130, 230),a second controlled switch (334, 344) electrically connecting the high-voltage distribution busbar (335, 345) to the second reversible electrical machine (200) via its second AC / DC converter (140, 240), characterized in that the method comprises for each controlled switch:, - a determination of the operating mode of the electrical machine coupled to the controlled switch, choosing between a motor mode and a generator mode, - a measurement of the current (Imesi) at the input of the controlled switch, and - a step of opening the controlled switch if, at the same time: - the measured current (Imesi) is in the opposite direction to the expected nominal current in the determined operating mode of the electrical machine, and - the measured current value (Imesi) is greater than at least one current threshold (Iseuiii), the value of the current threshold depending on the operating mode of the electrical machine, and the measured current value (Imesi) being compared to a first current threshold (Iseuiimax) above which the controlled switch is opened without delay, then to a second current threshold (læuiimin) below which the controlled switch remains closed, the value of the first current threshold (Iseuiimax) being greater than the value of the second current threshold (Iseuiimin).

2. A method according to claim 1, wherein, when the measured current value (Imesi) is between the first current threshold (Iseuiimin) and the second current threshold (Iseuiimax), the controlled switch opening step further comprises: - a determination of a confirmation time interval dependent on the value of the measured current (Imesi), - successive additional measurements of the input current of the controlled switch during the confirmation time interval, - a comparison of a cumulative energy value Ecumul to a tolerated absorbed energy threshold Eseuil, the cumulative energy value Ecumul being obtained by integrating said current measurement and said successive complementary current measurements and, - an opening of the controlled switch if the value of the cumulative energy Ecumul is greater than the tolerated absorbed energy threshold Eseuil.

3. A method according to any one of claims 1 or 2, further comprising, for each controlled switch, - a measurement of the voltage (Vmesi) at the input of the controlled switch, - the step of opening the controlled switch being carried out only if, in addition, the measured voltage (Vmesi) is less than a voltage threshold (Vseuiii).

4. Method according to claim 3, wherein each current measurement (Imesi) is associated with a voltage measurement (Vmesi).

5. A method according to any one of claims 1 to 4, wherein each controlled switch has a first normally open auxiliary contact and a second normally closed auxiliary contact, the method further comprising, for each controlled switch having been opened, a closing step if both: - The first auxiliary contact is open - the second auxiliary contact is closed and, - the measured current (Imesi) at the input of the controlled switch is zero.

6. An electrical hybridization system for an aircraft (400), the system comprising a first reversible electric machine (100) for connection to a low-pressure shaft, a second reversible electric machine (200) for connection to a high-pressure shaft, two electrical power distribution units (330, 340), and a control board (390), each reversible electric machine (100, 200) comprising a first winding (110, 210) associated with a first AC / DC converter (130, 230) and a second winding (120, 220) associated with a second AC / DC converter (140, 240), and each electrical power distribution unit (330, 340) comprising a high-voltage distribution busbar (335, 345), a first controlled switch (333, 343) electrically connecting the high-voltage distribution busbar (335, 345) to the first reversible electric machine (100) via its first AC / DC converter (130, 230),a second controlled switch (334, 344) electrically connecting the high-voltage distribution busbar (335, 345) to the second reversible electrical machine (200) via its second AC / DC converter (140, 240), the system being characterized in that the control board (390) is configured to implement the method according to one of the preceding claims.

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