ELECTRIC CHARGER FOR AERONAUTICAL MAINTENANCE EQUIPMENT

Abstract

The invention concerns a charger for aeronautical maintenance equipment, the charger comprising at least one so-called “high-frequency” input electrical connector comprising a plurality of power supply pins capable of receiving a three-phase AC voltage delivered by an external power supply source at a frequency of 400 Hz, and two detection pins, a so-called “high-frequency” charging module, connected to the at least one high-frequency input electrical connector, intended to be connected to a power storage module of the aeronautical maintenance equipment, and capable of converting the AC voltage received at the plurality of power supply pins of the high-frequency input electrical connector into a DC voltage for charging the storage module, and a control module capable of generating a detection voltage between the detection pins of the high-frequency input electrical connector allowing the external power supply source, when it detects the detection voltage, to authorize the supply of the AC voltage to the plurality of power supply pins of the high-frequency input electrical connector.

Claims

1-14. (canceled)

15. A charger for aeronautical maintenance equipment, said charger comprising: at least one high-frequency input electrical connector comprising a plurality of supply pins able to receive a three-phase AC voltage delivered by an external power source at a frequency of 400 Hz, and two detection pins, a high-frequency charging module connected to said at least one high-frequency input electrical connector and for being connected to an electric energy storage module of said aeronautical maintenance equipment, said high-frequency charging module configured to convert the AC voltage received on the plurality of power supply pins of the at least one high-frequency input electrical connector into a direct current voltage to charge said storage module, a control module configured to generate a detection voltage across the detection pins of the at least one high-frequency input electrical connector for the external power source, upon detecting said detection voltage, to allow supply of the AC voltage to the plurality of supply pins of the at least one high-frequency input electrical connector.

16. The charger of claim 15, wherein the control module is configured to receive a set point from a monitoring module of the storage module and to regulate the DC voltage supplied by the high-frequency charging module depending on said set point.

17. The charger according to claim 15, wherein the at least one high-frequency input electrical connector comprises a plurality of high-frequency input electrical connectors.

18. The charger according to claim 15, wherein the high-frequency charging module comprises a rectifier and a step-up converter.

19. The charger according to claim 15, comprising: at least one low-frequency input electrical connector distinct from the at least one high-frequency input electrical connector and configured for receiving a single-phase or three-phase AC voltage delivered by an external power source at a frequency of between 45 and 65 Hz, a low-frequency charging module, connected to the at least one low-frequency input electrical connector and for being connected to the storage module, said low-frequency charging module configured for converting the AC voltage received on the at least one low-frequency input electrical connector into a DC voltage for charging the storage module.

20. The charger according to claim 19, wherein the low-frequency charging module and the high-frequency charging module are implemented by a same physical entity in a single low-frequency or high-frequency charging module.

21. The charger according to claim 20, wherein the control module is configured to detect connection of an external power source to the at least one high-frequency input electrical connector or to the at least one low-frequency input electrical connector and to adapt operation of the low-frequency or high-frequency charging module depending on the frequency of the AC voltage provided on the input electrical connector detected.

22. The charger according to claim 19, wherein the low-frequency charging module and the high-frequency charging module are implemented by two distinct physical entities.

23. The charger according to claim 22, wherein the control module is configured to detect connection of an external power source to the at least one high-frequency or low-frequency input electrical connector and to electrically connect the at least one low-frequency input electrical connector to the low-frequency charging module when the connection has been detected on the at least low frequency input electrical connector or the at least one high-frequency input electrical connector to the high-frequency charging module when the connection has been detected on the at least one high-frequency input electrical connector.

24. The charger according to claim 15, wherein the control module is configured to determine or receive charging power information from the external power source and to adapt the charging current of the storage module based on said charging power information.

25. An aeronautical maintenance equipment for use in an aeronautical zone, said aeronautical maintenance equipment comprising: the charger according to claim 15, a storage module, connected to said charger, configured to store electric energy when said storage module is supplied with a DC voltage delivered by said charger.

26. The aeronautical maintenance equipment according to claim 25, comprising a power generation module, connected to the storage module, configured to produce a high-frequency or low-frequency DC or AC voltage from a fuel or a fuel cell in order to recharge the storage module.

27. A system comprising the aeronautical maintenance equipment, according to claim 25, and an external power source, electrically connected to said aeronautical maintenance equipment, said external power source being able to deliver a single-phase or three-phase 50 or 60 Hz or three-phase 400 Hz AC voltage, to charge the storage module of the aeronautical maintenance equipment via the charger of said aeronautical maintenance equipment.

28. A method for charging an electric energy storage module of the aeronautical maintenance equipment, according to claim 25, by an external power source capable of delivering a three-phase AC voltage delivered at a frequency of 400 Hz, said method comprising the steps of: electrically connecting the external power source to the at least one high-frequency input electrical connector of the charger of the aeronautical maintenance equipment so as to deliver a three-phase AC voltage at a frequency of 400 Hz, converting, by the high-frequency charging module of the charger of the aeronautical maintenance equipment, said AC voltage into a DC voltage, charging the storage module of the aeronautical maintenance equipment from said DC voltage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Further characteristics and advantages of the invention will become more apparent upon reading the following description. The latter is purely illustrative and should be read in conjunction with the appended drawings in which:

[0054] FIG. 1 schematically illustrates an embodiment of the aeronautical maintenance equipment according to the invention.

[0055] FIG. 2 schematically illustrates a first embodiment of the charger according to the invention.

[0056] FIG. 3 schematically illustrates a second embodiment of the charger according to the invention in which the high-frequency charging module and the low-frequency charging module are two distinct physical entities.

[0057] FIG. 4 schematically illustrates the second embodiment of the charger according to the invention in which the high-frequency charging module and the low-frequency charging module are implemented by one and a single physical entity.

[0058] FIG. 5 schematically illustrates one advantageous example of a step-up converter of a high-frequency charging module of the charger of FIGS. 2 to 4.

[0059] FIG. 6 schematically illustrates one exemplary implementation of the invention in which the aeronautical maintenance equipment is a ground power unit.

DETAILED DESCRIPTION

[0060] The charger according to the invention is to be on-board an aeronautical maintenance equipment of an aeronautical zone such as, for example, an airport zone, an aircraft manufacturing or maintenance hangar, a civil or military air base, etc. Such an aeronautical maintenance equipment may be mobile (cart, tractor, . . . ) or stationary, that is mounted at an aircraft parking point, for example in the ground or in a technical room, in a box or in a cabinet. The aeronautical maintenance equipment comprises an electric energy storage module that needs to be recharged when its energy level is low. The aeronautical maintenance equipment may be, for example, a Battery Ground Power Unit (GPU), a battery-powered push-back tractor, or any other battery-electric equipment that requires recharging. The electric energy storage module of the aeronautical maintenance equipment is capable of being recharged from an external power source delivering an AC voltage of frequency 400 Hz, or optionally even 50 or 60 Hz, such power sources being common in aeronautical zones and especially in airports.

[0061] Aeronautical Equipment 1

[0062] One embodiment of the aeronautical maintenance equipment 1 according to the invention has been represented in FIG. 1. The aeronautical maintenance equipment 1 comprises a charger 10 according to the invention and a storage module 20 connected to said charger 10. In FIG. 1, the aeronautical maintenance equipment 1 is electrically connected to an external power source 2 allowing electrical charging of said storage module 20 via said charger 10.

[0063] The storage module 20 is electrically rechargeable in order to store electric energy that it can then release. More specifically, in a charge mode, the storage module 20 is able to store electric energy when a DC voltage provided by the external power source 2 via the charger 10 is inputted to said storage module 20. In a discharge mode, the storage module 20 is able to output a DC output voltage to supply an entity internal or external to the aeronautical maintenance equipment 1. The storage module 20 may be especially in the form of an electric battery or a plurality of electric batteries, for example of the lithium-ion type, in a manner known per se.

[0064] FIG. 2 schematically illustrates a first embodiment of the charger 10 according to the invention.

[0065] Charger 10

[0066] The charger 10 comprises at least a so-called “high-frequency” electrical input connector 110, a so-called “high-frequency” charging module 120 and a control module 130. In the examples of FIGS. 2 through 4, the charger 10 comprises two high-frequency input electrical connectors 110, but of course, in other embodiments, the charger 10 could comprise a single high-frequency input electrical connector 110 or more than two high-frequency input electrical connectors 110.

[0067] High-Frequency Input Electrical Connector 110

[0068] The high-frequency input electrical connector 110 allows connection of the aeronautical maintenance equipment 1 to an electrical external power source 2 (not represented in FIGS. 2 through 4 for the sake of clarity) delivering a high-frequency AC voltage at a frequency of 400 Hz via an electrical cable 3 (FIG. 1). The external power source 2 may be mobile or stationary and for example may be an electric power unit operating with fuel (diesel, gasoline, bioethanol, etc.) or a fuel cell, a push-back tractor equipped with a high-frequency electric power unit, a power grid, or any other equipment capable of delivering an AC voltage at a frequency of 400 Hz, in particular equipment commonly used in aeronautical zones capable of delivering a voltage in the order of 200V between phases and with frequency 400 Hz.

[0069] The high-frequency input electrical connector 110 comprises supply pins 111 able to receive a three-phase AC voltage delivered by the external power source 2 at a frequency of 400 Hz, and two detection pins 112. In the case of a three-phase AC voltage, the supply pins 111 comprise three phase-type supply pins and one neutral-type supply pin. The geometry of the high-frequency input electrical connector 110 is such that, when connecting the external power source 2, it is necessary to fully insert the plug connectors of the external power source 2 into the supply pins 111 of the high-frequency input electrical connector 110 so that a voltage, for example 28 V, is generated across the detection pins 112. The external power source 2 generates the AC voltage only when it detects a voltage across the detection pins 112, thereby avoiding any arcing during connection. Preferably, the high-frequency input electrical connectors 110 are in accordance with international standard IS0461.

[0070] High-Frequency Charging Module 120

[0071] The high-frequency charging module 120 is connected, on the one hand, to the high-frequency input electrical connectors 110 and, on the other hand, to the storage module 20. The high-frequency charging module 120 is capable of converting the AC voltage received on the power supply pins 111 of the high-frequency input electrical connector 110 into a preferably regulated, DC voltage, for recharging said storage module 20. More precisely, the high-frequency charging module 120 is capable of converting an AC voltage of frequency 400 Hz into a DC voltage of, for example, between 300 Vdc and 900 Vdc in the case of a three-phase power supply depending on the voltage of the storage module 20, in order to supply electric energy to the storage module 20 in order to recharge it. Advantageously, the high-frequency charging module 120 is capable of regulating the DC voltage it delivers based on a setpoint received from a management module of the storage module 20, as will be described below.

[0072] In this example, with reference especially to FIGS. 2 and 4, the high-frequency charging module 120 comprises a rectifier 120A and a step-up converter 120B.

[0073] The rectifier 120A, which may be passive or active, is capable of converting the AC voltage received at the high-frequency input electrical connector 110 into a substantially DC voltage but with non-constant amplitude. The step-up converter 120B, which is active, is connected to the rectifier 120A and is able to increase value of the DC voltage supplied by said rectifier 120A.

[0074] Control Module 130

[0075] The control module 130 is able to generate a detection voltage between the detection pins 112 of the high-frequency input electrical connector 110 enabling the external power source 2 to allow supply of the AC voltage to the supply pins 111 of the high-frequency input electrical connector 110 as explained above.

[0076] A second embodiment of the charger 10 according to the invention has been represented in FIGS. 3 and 4.

[0077] In this second embodiment, the charger 10 comprises, further to the high-frequency input electrical connector 110, the high frequency charging module 120 and the control module 130, a low-frequency input electrical connector 140 and a low-frequency charging module 150.

[0078] Low Frequency Input Electrical Connector 140

[0079] The low-frequency input electrical connector 140 is distinct from the high-frequency input electrical connectors 110 and allows the aeronautical maintenance equipment 1 to be connected to an external power source (not represented in FIGS. 3 and 4) delivering, via an electrical cable, a low-frequency AC voltage, for example of 50 Hz or 60 Hz. To this end, the low-frequency input electrical connector 140 comprises five supply pins 141: three phase pins, a neutral pin, and optionally an Earth pin.

[0080] By the terms “external power source”, it is meant, as previously, both mobile equipment such as, for example, a mobile or stationary power generator operating from a fossil fuel (diesel, gasoline, bioethanol, etc.) or a fuel cell, a power, especially domestic, grid, or any equipment capable of delivering an AC voltage at a frequency of between 45 and 65 Hz, for example 50 or 60 Hz, especially a voltage and a frequency of a domestic power grid, for example 230V and 50 Hz in single phase or 400V and 50 Hz in three phases.

[0081] Low-Frequency Charging Module 150

[0082] The low-frequency charging module 150 is connected, on the one hand, to said low-frequency input electrical connector 140 and, on the other hand, to the storage module 20 via the control module 130 and is capable of converting an AC voltage of frequency between 45 and 65 Hz into a DC voltage, for example between 200 Vdc and 400 Vdc in the case of a single-phase supply or between 300 Vdc and 900 Vdc in the case of a three-phase supply, depending on the voltage of the storage module 20, in order to supply electric energy to the storage module 20 in order to recharge it.

[0083] In particular, the control module 130 is able to alternately connect the high-frequency charging module 120 or the low-frequency charging module 150 when an electric power source is connected to one of the high-frequency electric power supply connectors 110 or the low-frequency electrical input connector 140, respectively.

[0084] In the example illustrated in FIG. 3, the high-frequency charging module 120 and the low-frequency charging module 150 are implemented by two distinct physical entities, that is, they are each implemented on an electronic circuit, the two electronic circuits being electrically independent of each other.

[0085] In this case, the control module 130 may advantageously be able to detect connection of an external power source to one of the high-frequency input electrical connectors 110 or to the low-frequency input electrical connector 140 and to electrically connect said high-frequency input electrical connector 110 to the high-frequency charging module 120 respectively when connection has been detected on said high-frequency input electrical connector 110 or the low-frequency input electrical connector 140 to the low-frequency charging module 150 when connection has been detected on the low-frequency input electrical connector 140. Once the connection is made, the AC voltage is converted to DC voltage by the high-frequency charging module 120 or the low-frequency charging module 150 respectively.

[0086] In the example of FIG. 4, the high-frequency charging module 120 and the low-frequency charging module 150 are implemented by one and a single entity, that is, a single electronic circuit implementing both functions.

[0087] In this case, the control module 130 is able to detect connection on one of the high-frequency input electrical connector 110 or the low-frequency input electrical connector 140 and to electrically connect said high-frequency input electrical connector 110 or the low-frequency input electrical connector 140 on which connection has been detected to the high-frequency charging module 120 or the low-frequency charging module 150, respectively. Furthermore, in this case, the rectifier 120A and the step-up converter 120B are further able to convert an AC voltage 50 or 60 Hz to a DC voltage adapted to charge the storage module 20 when the storage module 20 is connected to the charger 10.

[0088] In the embodiments illustrated in FIGS. 2 through 4, the control module 130 is able to control one or more 400 Hz three-phase contactors 11, each connected between a high-frequency input electrical connector 110 and the high frequency charging module 120.

[0089] In the case of FIG. 3, the control module 130 is able to open and close command a contactor I2A placed between the high-frequency charging module 120 and the storage module 20, and a contactor I2B placed between the low-frequency charging module 150 and the storage module 20.

[0090] In the case of FIG. 4, the control module 130 is able to control a three-phase contactor 12 connected between the low-frequency input electrical connector 140 and the low-frequency charging module 150. The control module 130 is especially configured to open and close control the three-phase contactors I1 and the three-phase contactor 12 so that: [0091] the three-phase contactors I1 are closed and the three-phase contactor 12 is open in order to electrically supply the storage module 20 via the high-frequency charging module 120 when said high-frequency charging module 120 is electrically supplied with a 400 Hz external power source 2 via one of the high-frequency input electrical connectors 110, or [0092] the three-phase contactors I1 are open and the three-phase contactor 12 is closed in order to electrically supply the storage module 20 via the low-frequency charging module 150 when said low-frequency charging module 150 is electrically supplied with a 50 or 60 Hz external power source via the low-frequency input electrical connector 140, or [0093] the three-phase contactors I1 are open and the three-phase contactor 12 is open in order to electrically insulate the storage module 20 from outside, especially when the aeronautical maintenance equipment 1 is not in use.

[0094] The control module 130 may be configured to detect connection of an external power source 2 to one of the at least one high-frequency input electrical connector 110 or to the low-frequency input electrical connector 140 and/or to be manually commanded by an operator, for example, via keys, a touchscreen or a mobile terminal, for example, a smartphone, in order to switch the contactors I1 (and the contactor 12 if applicable) to the desired positions.

[0095] One example of a step-up converter 120B that may be implemented in each of the embodiments shown in FIGS. 2 through 4 has been represented in FIG. 5. In this example, the step-up converter 120B comprises a DC to AC voltage conversion stage 120B 1, an AC to DC voltage conversion stage 120B3, and a high-frequency transformer 120B2 connected between the DC to AC voltage conversion stage 120B1 and the AC to DC voltage conversion stage 120B3. The high-frequency transformer 120B2 advantageously enables the DC output voltage of the high-frequency charging module 120 to be adapted to the desired value to recharge the storage module 20 and the high-frequency charging module 120 to be galvanically insulated from the storage module 20 when the latter are electrically connected to each other.

[0096] It will be noted that in an alternative embodiment (not represented), in the case where the high-frequency charging module 120 and the low-frequency charging module 150 are implemented by a same physical entity, the charger 10 could comprise a first transformer between the contactor I1 and the high-frequency/low-frequency charging module 120, 150, and a second transformer between the contactor 12 and the high-frequency/low-frequency charging module 120, 150. The first transformer, a three-phase 400 Hz step-up transformer, would transform the 3×200V 400 Hz voltage into a 3×400V 400 Hz voltage. The second transformer, three-phase 50 Hz power, would insulate from the 50 Hz external power source. Thus the voltage level at the input of the rectifier 120A would always be the same and independent of the high (400 Hz) or low (50 or 60 Hz) frequency.

[0097] With reference to FIGS. 1 to 4 and in an advantageous manner, the aeronautical maintenance equipment 1 may comprise a monitoring module 30, for example of the BMS (Battery Monitoring System) type, capable of sending a voltage set point to the control module 130 of the charger 10 so that the control module 130 controls the high-frequency charging module 120 or the low-frequency charging module 150, as appropriate, in order to adjust its output voltage to said set point. To this end, the monitoring module 30 and the control module 130 may, for example, be connected by a CAN (Controller Area Network) bus type communication link. The setpoint may, for example, be generated by the monitoring module 30 as a function of the voltage defined across the storage module 20. The monitoring module 30 may especially measure said voltage and determine a set point allowing the storage module 20 to be charged, preferably optimally.

[0098] Referring again to FIG. 1, the aeronautical maintenance equipment 1 may also advantageously comprise a power generation module 40 capable of producing a low or high-frequency DC or AC voltage from a fossil fuel such as, for example, diesel or gasoline. Alternatively, the power generation module 40 could comprise a fuel cell coupled to a hydrogen tank to generate power. This power generation module 40, called a “range extender”, makes up a power generator on-board the aeronautical maintenance equipment 1. A DC voltage generated by the power generation module 40 enables the storage module 20 to be directly charged, while an AC voltage may be input by the power generation module 40 to the high-frequency charging module 120 or the low-frequency charging module 150 in order to be converted to a DC voltage to charge the storage module 20.

[0099] Preferably, at a given instant, only one of the high-frequency charging module 120, the low-frequency charging module 150, and the power generation module 40 is electrically connected to the storage module 20.

[0100] One particular embodiment of the aeronautical maintenance equipment 1 according to the invention has been represented in FIG. 6. In this embodiment, the aeronautical maintenance equipment 1 is of the battery ground power unit (Battery GPU) type and comprises, further to a high-frequency input electrical connector 110, the charger 10 and the storage module 20, an inverter 50 and an output electrical connector 60.

[0101] Inverter 50

[0102] The inverter 50 is connected to the storage module 20 and is able to convert DC voltage provided by said storage module 20, received at a so-called “DC” interface 51, into an adapted AC voltage, provided at a so-called “AC” interface 52, in order to electrically supply an aircraft 4, for example at a 200V AC voltage between phases oscillating at a frequency of 400 Hz.

[0103] Electrical Output Connector 60

[0104] The electrical output connector 60 is connected to the inverter 50 and is connected to the aircraft 4 via an electrical cable 5.

[0105] In this embodiment, the aeronautical maintenance equipment 1 advantageously comprises a contactor 14 and a contactor IS, both of which may be open or close commanded by the control module 130. The contactor 14 is connected between the storage module 20 and the inverter 50 to connect or disconnect them while the contactor IS is connected between the inverter 50 and the output electrical connector 60 also to connect or disconnect them.

Examples of Implementation

[0106] A) High Frequency Charging

[0107] In the example of the figures, an external power source may be connected to one or all of the high-frequency input electrical connectors 110. The external power source (reference 2 in FIG. 1) is, for example, an aircraft pushback tractor equipped with a high-frequency electrical generator or a ground power unit delivering a 200V phase-to-phase AC voltage at 400 Hz. When the external power source 2 is connected to the high-frequency electrical input connector 110, the control module 130 detects this connection and positions the contactor(s) I1 into the closed position. Alternatively, an operator could command the control module 130 to cause said control module 130 to switch the contactor(s) I1 into the closed position before connecting the external power source 2 to the high-frequency input electrical connector(s) 110. Once connected, the high-frequency charging module 120 converts the 400 Hz AC voltage delivered by the external power source 2 into a DC voltage to electrically supply the storage module 20 to recharge it with electric energy. Once charging is sufficient, the external power source 2 is disconnected from the aeronautical maintenance equipment 1, which may then be used to perform its original function.

[0108] B) Low-Frequency Charging

[0109] In the example of FIG. 3 or 4, the aeronautical maintenance equipment 1 is connected to a low-frequency external power source 2 which may for example in this case be an electric power unit with engine or electric motor or a stationary or mobile under-airplane power supply delivering a single-phase 230V AC voltage at 50 Hz or a three-phase 400V AC voltage at 50 Hz. When the external power source 2 is connected to the low-frequency input electrical connector 140, the control module 130 detects this connection and positions: [0110] in the case of FIG. 3, the control module 130 places the contactor 12A to open and the contactor I2B to close. Alternatively, an operator may command the control module 130 to cause said control module 130 to switch the contactor I2A to open and the contactor I2B to close prior to connecting the external power source to the low frequency input electrical connector 140, [0111] in the case of FIG. 4, the control module 130 places the contactor 11 to open and the contactor 12 to close. Alternatively, an operator may command the control module 130 to cause said control module 130 to switch the contactor I1 to open and the contactor 12 to close prior to connecting the external power source to the low-frequency input electrical connector 140.

[0112] Once connected, the low-frequency charging module 150 converts the 50 or 60 Hz AC voltage delivered by the external power source to the low-frequency input electrical connector 140 into a DC voltage for electrically supplying the storage module 20 to recharge it with electric energy. Once sufficiently charged, the external power source is disconnected from the aeronautical maintenance equipment 1 which may then be used to perform its original function.

[0113] C) Power Supply

[0114] In the case where the aeronautical maintenance equipment 1 is a ground power unit (FIG. 6), once connected to the aircraft 4, the control module 130 switches the contactors 14 and 15 to closed if necessary (that is, if they were not) so that the storage module 20 provides a DC voltage to the DC interface 51 of the inverter 50. The inverter 50 converts this voltage to an AC voltage, for example 200V phase-to-phase at 400 Hz, on the AC interface 52, which AC voltage then enables the aircraft 4 to be electrically supplied via the electrical output connector 60 and the electrical cable 5.

[0115] D) Autonomous Recharging (“Range Extender”)

[0116] When it is necessary to recharge the storage module 20 but no external power source 2 is available, an operator may command the control module 130 such that it actuates the power generation module 40 if present (FIG. 1) to produce a low or high frequency DC or AC voltage by burning fuel or via a fuel cell by recharging with dihydrogen. Once sufficient recharge is achieved, the control module 130 disconnects or commands shutdown of the power generation module 40 from the storage module 20. The aeronautical maintenance equipment 1 may then be used.

[0117] The charger 10 according to the invention thus advantageously allows the use of a 400 Hz AC voltage to charge a battery of an aeronautical maintenance equipment 1. Charging may advantageously be ultra-fast by using a plurality of high-frequency electrical input connectors 110 simultaneously connected to a plurality of external power sources 2. When the charger 10 comprises at least one low-frequency input electrical connector 140, charging may be performed both from an external power source 2 delivering a 400 Hz voltage and from an external power source delivering a 50 or 60 Hz voltage, thereby multiplying the number of sources that may be used in aeronautical zones to recharge batteries of aeronautical maintenance equipment 1. The aeronautical maintenance equipment 1 according to the invention advantageously makes it possible to use most of the external power sources 2 present in airport zones.