Method for monitoring and protecting an electrical hybridization system

Abstract

Method for monitoring and protecting an electrical hybridization system. The invention relates to a method for monitoring and protecting an electrical hybridization system for an aircraft (400), the system comprising a first reversible electrical machine (100), a second reversible electrical machine (200), and two electrical power distribution units (330, 340), each electrical power distribution unit (330, 340) comprising a high-voltage distribution busbar (335, 345), a first controlled switch, a second controlled switch (334, 344), the method comprising for each controlled switch: - a determination of the operating mode of the electrical machine coupled to the controlled switch, - a measurement of the current (Imes1) at the input of the controlled switch, and - a step of opening the controlled switch if, simultaneously: - the measured current (Imes1) is in the opposite direction to the expected nominal current,and - the measured current value (Imes1) is greater than at least one current threshold (Iseuil1). Figure for the abbreviation: Fig.3,

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 various states. In particular, an ambitious standard applies to both new types of aircraft and those currently 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 is working 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 hybrid networks and systems rely on simple and mostly passive devices. These protections primarily safeguard the electrical installation but not the 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, generator protection also exists, based on the thermal behavior of the generator windings and the dynamic voltage behavior to stay within the acceptable range for consumers.

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

[0007] Thus, there is a real need to carry out the monitoring and protection of an electrical hybridization system without the disadvantages inherent in the aforementioned known processes. Description of the invention

[0008] To this end, the invention proposes a method for monitoring and protecting an electrical hybridization system for an aircraft, 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, and two electrical power distribution units.Each electrical machine comprises 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 comprises 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, and a second controlled switch electrically connecting the high-voltage distribution busbar to the second reversible electrical machine via its second AC / DC converter.

[0009] 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 input current of the controlled switch, and - an opening step of the controlled switch if both of the following conditions are met: - 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.

[0010] Such a method makes it possible to detect a malfunction in the electric hybridization system quickly and accurately, and to isolate the faulty part.

[0011] To this end, 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 rating associated with the components or elements.

[0012] The current threshold is then set prior to the process based on the various acceptable current thresholds. Detection of a current exceeding the threshold indicates the presence of a fault in the electric hybrid system. In such a case, it is preferable to locate the fault in order to isolate only the system components affected by the malfunction. This prevents jeopardizing the operation of the electric hybrid system as a whole.

[0013] A direction of the rated current is assigned to each operating mode of the electrical machines in the electrical hybridization system. Determining the operating mode of the electrical machine makes it possible to determine the direction of the expected current in the absence of a fault. In generator mode, the electrical machine delivers a current, while in motor mode, it consumes a current supplied to it at the input.

[0014] The detection of a current direction opposite to the nominal current direction indicates the presence of a fault and allows the latter to be located.

[0015] Thus, it is possible to isolate only the parts affected by the malfunction and prevent damage to other components of the electric hybrid system. Electrical isolation is achieved by opening the relevant controlled switch. The method therefore makes it possible to isolate the defective components and the branch of the hybrid system affected by the malfunction while preventing the propagation of faults within the electric hybrid system.

[0016] Moreover, such a process makes it possible to maintain maximum availability of the other elements of the electric hybridization system.

[0017] According to a particular feature of the method, 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.

[0018] Comparing the current value at two different thresholds allows us to define three different protection regimes, the first of which is below which there is no need of protection, the second above which protection is immediate, and the third where protection can be adapted according to parameters.

[0019] 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.

[0020] According to a particular feature of the method, when the measured current value is between the first current threshold and the second current threshold, the step of opening the controlled switch may additionally 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.

[0021] This allows for 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 makes it possible to easily sample the input current to the controlled switch. Comparing each of the current measurements to the first current threshold allows for even more precise detection of a fault and even more effective triggering of the controlled switch.

[0022] According to a particular feature, the method may further include for each controlled switch, - a measurement of the input voltage of the controlled switch, - the opening step of the controlled switch being carried out only if, in addition, the measured voltage is less than a voltage threshold.

[0023] These additional steps and conditions for opening allow confirmation of a malfunction within the electric hybrid system before triggering the opening. Indeed, the presence of a measured voltage below a certain voltage threshold confirms the presence of a short circuit within the electric hybrid system.

[0024] According to a particular feature of the process, each current measurement can be associated with a voltage measurement.

[0025] According to another particular feature, 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 having 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.

[0026] Such a method makes it possible to confirm the absence of a fault in the system and to verify the state of the controlled switch before reconnecting it. Thus, it is possible to safely trigger the reconnection of the controlled switch.

[0027] 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 connects 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

[0028] 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.

[0029] [Fig-1] Fig. 1 illustrates a first example of an electric hybridization system according to the invention,

[0030] [Fig.2] Fig.2 illustrates the flowchart of the steps of a first embodiment of a process according to the invention,

[0031] [Fig.3] Fig.3 illustrates the flowchart of the steps of a second embodiment of a process according to the invention,

[0032] [Fig.4] Figure [Fig.4] illustrates two curves of the current threshold values ​​and the duration of the corresponding confirmation for each value for the process of [Fig.3]. Description of the implementation methods

[0033] 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.

[0034] Figure 1 illustrates an example of an electrical hybridization system according to the invention.

[0035] The electrical hybridization system 400 comprises a first electrical machine 100, a second electrical 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.

[0036] The first electric machine 100 and the second electric machine 200 can each be rotating electric machines. More particularly, the electric machines 100 and 200 can each be rotating electric machines of the PMG (Permanent Magnet Generator) type, 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 [Fig. 1]. The second electric machine 200 is intended to be connected to a high-pressure shaft of a turbomachine not shown in [Fig. 1].

[0037] 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.

[0038] 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.

[0039] The electrical power distribution units 330 and 340 are also known as PDMU, which stands for Power Distribution Management Unit.

[0040] A control card 390 can be arranged in the first electrical power distribution unit 330 and / or in the second power distribution unit electrical 340. This control card 390 is configured to control the protection elements of the electrical hybridization system 400.

[0041] 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 further comprises a high-voltage distribution busbar 345, a first switch 343, a second switch 344, a third switch 346 and several fourth switches 348.

[0042] 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.

[0043] When the controlled switches are electromechanical or electronic controlled switches, they can be in bipolar configuration in the hybridization system 400.

[0044] The number of high voltage distribution bars is not limiting to the invention.

[0045] According to, a variant of each of the first power distribution units electrical 330 and second electrical power distribution unit 340 may include a first positive high voltage distribution bar and a second negative high voltage distribution bar.

[0046] According to yet another variant, each of the first electrical power distribution unit 330 and second electrical power distribution unit 340 may include a number of high voltage distribution bars greater than two.

[0047] The first controlled switch 333 of the first electrical power distribution unit 330 electrically connects the first electrical machine 100 to the high-voltage distribution 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.

[0048] The second controlled switch 334 of the first electrical power distribution unit 330 electrically connects the second electrical machine 200 to the high-voltage distribution busbar 335 of the first electrical power distribution unit 330, via the first AC / DC converter 230 connected to the second electrical 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 electrical machine 200 via the first AC / DC converter 230 of the second electrical machine 200.

[0049] The first controlled switch 343 of the second electrical power distribution unit 340 electrically connects the first electric machine 100 to the high-voltage distribution 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.

[0050] The second controlled switch 344 of the second electrical power distribution unit 340 electrically connects the second electric machine 200 to the high-voltage distribution 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.

[0051] The first electrical power distribution unit 330 has a first output 337 for connection to the aircraft's electrical network. And, the second electrical power distribution unit 340 has a first output 347 for connection to the aircraft's electrical network.

[0052] 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 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 intended to be connected to the aircraft's electrical network.

[0053] The local loads 350 to 355 may include aircraft components other than those powered by the aircraft's electrical network. 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 the local loads 350, 351, and 352.

[0054] 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.

[0055] The electrical hybridization system 400 further comprises sensors 391 to 398, as illustrated in [Fig. 1]. In the example shown in [Fig. 1], each sensor 391 to 398 is mounted respectively at the input of one of the controlled switches 333 to 338, and 343 to 348. These sensors 391 to 398 allow 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 electrical resistance. The number of sensors and their locations are not limiting to the invention.

[0056] Sensors 391 to 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.

[0057] 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.

[0058] The current sensor makes it possible in particular to fix the direction of the nominal current for each operating mode of the electrical machines.

[0059] 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.

[0060] When the controlled switch is open, the first normally open auxiliary contact is open and the second normally closed auxiliary contact is closed

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

[0062] 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.

[0063] Figure 2 illustrates a first example of implementing the process according to the invention implemented by the control board 390 to control the protection elements of the electric hybrid system 400. The method is designed to protect and monitor the electric hybrid system described above.

[0064] In a first step E1, 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 in generator mode. This step makes it possible to determine 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.

[0065] When the first electric machine 100 operates in motor mode, a source supplies electrical energy to the first distribution unit 330 and / or the second distribution unit 340. In one variant, the source supplying energy can be the aircraft's electrical network or the second electric machine 200.

[0066] 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.

[0067] 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 both electrical power distribution units 330 and 340. The electrical energy received by the second The 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.

[0068] 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.

[0069] In one variant, the first distribution unit 330 can be powered by a separate energy source from that powering the second distribution unit 340.

[0070] 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.

[0071] 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.

[0072] 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 a positive current. 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.

[0073] 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 The current measured by the 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.

[0074] The direction of the nominal current attributed to each operating mode is not limiting of the invention.

[0075] According to one embodiment, 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.

[0076] 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 input current Imesian of the controlled switch by the current sensors 391 and 395 for each distribution unit 330 and 340, as illustrated in [Fig.2].

[0077] When the electrical hybridization system 400 includes sensors mounted at the input of the controlled switches, the current measurement can be performed at the sensors. In the example shown in [Fig. 1], the current measurement step E2 can be performed at sensors 391 to 398. For example, if the input current of the controlled switch 333 is to be measured, the current measurement can be performed at sensor 391. In the case where 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.

[0078] 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.

[0079] 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.

[0080] In a distribution phase, the first electric machine 100 and the second electric machine 200 operate in generator mode.

[0081] During a start-up 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 start-up.

[0082] During a motor assistance phase, the first electric machine 100 or the second electric machine 200 operates in generator mode and supplies the other electric machine.

[0083] In a step E3, following the current measurement step E2, the direction of the measured current is compared to the direction of the nominal current expected in the operating mode determined during step E1.

[0084] The threshold can also be defined according to the position of the controlled switch in the hybridization system, the type of protection provided in the hybridization system, and the component rating. The protection provided in the hybridization system can be, for example, source protection, load protection, or cable protection.

[0085] As illustrated in [Fig.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 a step E6, unless the value of the measured current Imesi is greater than a current threshold Leuii, in which case the controlled switch is opened in a 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.

[0086] In one embodiment, the threshold can be defined using a thermocouple. In this case, the thermocouple is installed near the controlled switch, and then the current is gradually increased. The increase in current generates a temperature increase. 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 not to be exceeded corresponds to the current threshold.

[0087] 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 |Iseuin|, as illustrated in [Fig. 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.

[0088] 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 hybridization system. The fault will then be located upstream of where the measurement was taken; in this case, upstream of the input of the controlled switch.

[0089] 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 in controlled switch input 333, controlled switch 333 is open in step E4.

[0090] 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.

[0091] Figure 3 illustrates a second example of a method according to the invention.

[0092] In the example illustrated in [Fig. 3], the process comprises the same steps E1, E2, E3 as in the process illustrated in [Fig. 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 |Leuiii| described previously may be present, as illustrated in [Fig. 3].

[0093] Instead of the comparison step E5, when the direction of the measured current is nominal, the method comprises a first comparison E51 of the measured current value Imesi to the value of a first current threshold Leuiimax, and a second comparison E52 of the measured current value Imesi to the value of a second current threshold Leuiimin. The value of the first current threshold Leuiimax is greater than the value of the second current threshold Lmiimin.

[0094] 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 Leuiimin, in steps E51 and E52.

[0095] If the value of the measured current Imesi is greater than or equal to that of a first current threshold Leuiimax, the controlled switch is opened in step E4.

[0096] When the measured current value Imesi is less than the value of the first current threshold Leuiimax and is greater than or equal to the value of the second current threshold Leuiimin, the controlled switch is held in the closed position in a step E6, as illustrated in [Fig.4].

[0097] If the measured current value Imesi is greater than the value of the second current threshold Leuiimin and less than the value of a first current threshold Leuiimax, 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 Leuiimin and the value of the first current threshold Leuiimax.

[0098] The value of the confirmation time depends on the value of the measured current Imesi.

[0099] 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.

[0100] Depending on a particular characteristic, the confirmation time can be between 0.5 and 100 seconds.

[0101] The current measured during each of the successive complementary measurements is integrated over the confirmation time. This integration corresponds to a cumulative energy Ecumul.

[0102] 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.

[0103] The cumulative energy Ecumul is then compared to the tolerated absorbed energy threshold Eseuil. When the value of the cumulative energy Ecumul is greater than the tolerated absorbed energy threshold Eseuil, the controlled switch is opened, in step E4, as illustrated in [Fig.4].

[0104] 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.

[0105] The figure illustrates two curves of the current threshold values ​​and the corresponding confirmation time for each value for the process illustrated in [Fig.3].

[0106] Curve B in dashed 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.

[0107] The continuous line curve A 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.

[0108] For example, when the electric machine operates in generator mode, a second threshold Iseuiimin is defined at +200A and a first threshold Iseuiimax is defined at +700A.

[0109] When a measured current Imesi of +600A is observed, the controlled switch is held in the closed position in 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.

[0110] 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.

[0111] In a case where a current Imesi equal to +400A is measured, 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 measured current value Imesi is compared to the value of the first current threshold Leuiimax. The measured current value Imesi is also compared to the value of the second current threshold Leuiimin. The value of +400A of the measured current Imesi is greater than the value of +200A of the second current threshold Leuiimin and less than the value of +700A of the first current threshold Leuiimax.

[0112] The comparison of the measured current value Imesi with the value of the first current threshold Leuiimax is carried out before the comparison of the measured current value Imesi with the value of the second current threshold Leuiimin-

[0113] In one variant, the comparison of the measured current value Imesi with the value of the first current threshold Leuiimax and with the value of the second current threshold Leuiimin is carried out simultaneously.

[0114] The value of +400A of the measured current Imesi lies between the value of the first threshold Leuiimax and the value of the second threshold Leuiimin-. In this case, a confirmation time depending on the value of the measured current Imesi is determined, and this during a step E8. The confirmation time corresponding to a measured current Imesi = +400A is 3 seconds, as illustrated in [Fig.4].

[0115] Successive additional measurements of the input current of the controlled switch are performed during the confirmation period, in step E9. For a measured current Imesi = +400 A, successive additional current measurements are performed 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.

[0116] For the measured current Imesi = +400A, when the cumulative energy value Ecumul obtained after integrating successive complementary current measurements exceeds the tolerated absorbed energy Eseuil, equal to 200A after 3 seconds, the controlled switch is opened. Otherwise, the controlled switch is held in the closed position during step E3, as illustrated in [Fig. 4].

[0117] For example, when the electric machine is operating in motor mode, a second threshold Leuiimin can be set at -250A and a first threshold Leuiimax can be set at -700A.

[0118] For example, when a current Imesl equal to -150A is measured, 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 motor mode, as it is a positive current. Thus, in motor mode, a current Imesl equal to -150A will not cause the controlled switch to open. Such a current is permanently above curve B.

[0119] 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.

[0120] 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.

[0121] The sum of the current values ​​measured during each of the successive supplementary measurements carried out during the confirmation period gives the cumulative energy Ecumul. When the value of the cumulative energy Ecumul is greater than the tolerated absorbed energy threshold Eseuil, here equal to -300A after a maximum of 4 seconds, the controlled switch is opened.

[0122] According to a particular feature, the method may further include, for each controlled switch, measuring the voltage Vmesi at the input of the controlled switch. In this case, the measured voltage value is compared to the value of a voltage threshold Vseuiii.

[0123] Measuring such a voltage makes it possible to confirm the presence of a fault in the electrical hybridization system.

[0124] For the example illustrated in [Fig.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, if the value of the measured current Imesi is greater than or equal to the value of the current threshold Imesi and if the value of the measured voltage Vmesi is less than the value of the voltage threshold V h ' threshold 1 •

[0125] For the method illustrated in [Fig. 3], when the measured current value Imesi is greater than the value of the second current threshold Iseuiiminet 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 Vh' threshold 1 •

[0126] For the process illustrated in [Fig. 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 Vh' threshold 1 •

[0127] 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 threshold Iseuiimax, and it will be accompanied by the presence of a voltage drop.

[0128] When the controlled switches of the electrical hybridization system have a first normally open auxiliary contact and a second normally closed auxiliary contact, the method may further include, for each controlled switch, a closing step. This closing step is performed once the fault in the electrical hybridization system has been resolved. Before initiating the closing, it is verified that the controlled switch is in an open state, i.e., that the first normally open auxiliary contact is indeed open, and that the second normally closed auxiliary contact is indeed closed.

[0129] 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 Imesen at the switch input is zero.

[0130] 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 measured at the input of the controlled switch corresponds to a second verification that the controlled switch is in the open position.

[0131] Thus, it is possible to engage the closing of the controlled switch in a safe manner.

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 electric machine (200) via its second AC / DC converter (140, 240), characterized in that the method comprises, for each controlled switch: - determining the operating mode of the electric machine coupled to the controlled switch from among a motor mode and a generator mode, - measuring the current (Imesi) at the input of the controlled switch, and - opening the controlled switch if both of the following conditions are met: - the measured current (Imesi) is in the opposite direction to the expected nominal current in the determined operating mode of the electric machine, and - the value of the measured current (Imesi) is greater than at least a current threshold (Iseuiii), the value of the current threshold depending on the operating mode of the electric machine.

2. A method according to claim 1, wherein in the opening step of the controlled switch, the measured current value (Imesi) is compared to a first current threshold (Iseuiim ax) above at which the controlled switch is opened without delay, then at a second current threshold (Iseuiim in) below which the controlled switch remains closed, the value of the first current threshold (Iseuiim ax) being greater than the value of the second current threshold (Iseuiim in)-

3. A method according to claim 2, wherein, when the measured current value (Imesi) is between the first current threshold (Iseuiimin) and the second current threshold (Iseuiimax), the step of opening the controlled switch further comprises: - a determination of a confirmation time interval depending on the measured current value (Imes J, - successive complementary measurements of the current at the input of the controlled switch during the duration of 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 an integration of said current measurement and said successive complementary current measurements and, - an opening of the controlled switch if the cumulative energy value Ecumul is greater than the tolerated absorbed energy threshold Eseuil.

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

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

6. A method according to any one of claims 1 to 5, 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,

7. - the measured current (Imesi) at the input of the controlled switch is zero. An electrical hybrid system for an aircraft (400), the system comprising a first reversible electric machine (100) intended to be connected to a low-pressure shaft, a second reversible electric machine (200) intended to be connected 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 electric machine (100) reversible 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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