Aircraft electrical architecture

Abstract

The present invention relates to an electrical architecture of an aircraft, comprising: a plurality of main generators (GEN1, GEN2), each associated with a propulsion engine of the aircraft; a plurality of main grids (AC1, AC2, basic AC), each associated with the main generator in nominal operating mode; an integrated auxiliary power grid (RES); an electric energy accumulation device (BAT‑HVDC) directly connected to the auxiliary network; a first electric energy converter (CP1), which is arranged between the auxiliary network and a first main grid of the main network, thereby allowing energy to be transferred from the first main grid of the main network to the auxiliary network, the first electric energy converter (CP1) being intended to supply electric energy to the electric energy accumulation device in nominal operating mode; a second electric energy converter (CP2), which is arranged between the auxiliary network and a second main grid of the main network, thereby allowing energy to be transferred from the auxiliary network to the second main grid of the main network.

Description

Technical Field

[0001] The present invention relates to improving the electrical architecture of aircraft. On commercial aircraft, electrical energy is typically generated by main generators mechanically coupled to the aircraft's propulsion engines. Each generator supplies an alternating current (AC) voltage, which is fed into the aircraft's electrical grid, which distributes the AC or direct current (DC) power required to operate electrical loads located in the fuselage and engine areas. Background Art

[0002] Traditionally, electricity with a fixed frequency AC current (conventionally at 400 Hz) can be generated on commercial aircraft based on gas turbines rotating at variable speed. The nominal voltage of the onboard AC network is usually 115 V. On some modern aircraft, this voltage has been increased to 230 V. To achieve this, a speed control system is installed between the shaft of the gas turbine and the AC generator, which is then able to rotate at a fixed speed to produce the desired fixed frequency. Speed ​​control systems that implement hydraulic converters are known in the literature under the name CSD "Constant Speed ​​Drive". The generator and the hydraulic converter can be integrated to form a device known in the literature under the name IDG "Integrated Drive Generator". Recently, attempts have been made to eliminate these hydraulic converters by switching to variable speed AC generators, thereby producing an onboard network with a variable frequency, for example between 400 Hz and 800 Hz.

[0003] On long-range aircraft, other generators are often present, notably auxiliary power units and ram air turbines.

[0004] Auxiliary power units are known in the literature and are referred to hereinafter by their acronym APU. An APU is an auxiliary unit which generally comprises a gas turbine coupled to an electric generator. The APU is generally located in the tail cone of the aircraft and is supplied with kerosene from the aircraft's fuel tanks. The APU is started by the aircraft's batteries. The APU is intended to produce air for the aircraft's air conditioning system and to start the propulsion engines if they are equipped with air starting systems. The APU can also generate hydraulic and / or electrical energy to supply power to various onboard systems on the ground when the propulsion engines are stopped and to start the engines if they are equipped with electric starters. The APU can also be used in flight in the event of a failure of the main generator.

[0005] Ram air turbines are known in the literature and are hereinafter referred to by their acronym, RAT. A RAT consists of an air turbine arranged in an aircraft bay. In the event of a loss of the aircraft's primary power source (the main generator coupled to the propulsion engines and APU), the RAT is deployed in flight. The RAT is driven by the airflow generated by the aircraft's forward motion. The RAT is coupled to a hydraulic pump or an alternating current generator. The RAT serves as a backup energy source onboard the aircraft.

[0006] The APU and RAT represent the primary loads carried by the aircraft. The APU and RAT are not used during the primary flight phase. Furthermore, APU use is reduced when the aircraft is grounded to avoid contamination risks. Some airports even require the use of available air and electric power services.

[0007] On the ground, the aircraft can also be powered by an external generator, commonly called a ground supply unit, which makes it possible to not use the APU.

[0008] The various generators are connected to an electrical power distribution system, known in the literature and hereinafter referred to by its acronym EPDS. The EPDS itself consists of a primary battery cell and a secondary battery cell. The primary battery cell includes power distribution bars that are isolated from each other during nominal operation. In the event of the loss of one or more generators, the power bars can be interconnected. Not all power bars operate at the same voltage. They are interconnected via power converters, allowing the various voltage and frequency levels required for the operation of the various loads to be created. The secondary battery cells control and protect the aircraft's electrical loads.

[0009] EPDS makes it possible to create the various voltages required for aircraft operation, such as fixed or variable frequency voltages like 115VAC or 230VAC, or a controlled voltage of 28VDC intended for low-power loads such as avionics systems or flight control computers.

[0010] EPDS also makes it possible to separate so-called "essential" loads from "non-essential" loads on separate power distribution strips. Essential loads are understood to be any load required to ensure the correct operation of the aircraft in the event of a malfunction. Powering essential loads ensures operational continuity in the complete safety of the aircraft and its passengers.

[0011] Modern aircraft can be found in high-voltage direct current (HVDC) networks, which are known in the literature and hereinafter referred to by their acronym, HVDC. EPDS are capable of generating HVDC voltages, which are obtained by rectifying the regulated three-phase AC voltage generated by the main generator. A commonly used HVDC voltage is 540 VDC. Voltages of 350 V and 270 V are also considered. The main reason for the development of HVDC networks is that they can be used to power certain loads, in particular synchronous motors or actuators that cannot operate without a DC to AC power converter. This converter is then powered by the HVDC network.

[0012] In commercial aviation, the current trend is toward increasing the amount of electrical components. Some hydraulic components, such as flight controls, are being replaced by electrical systems. Furthermore, cabin air conditioning is also trending toward electrification.

[0013] As the trend toward aircraft electrification leads to a significant increase in the proportion of loads requiring DC power, some aircraft manufacturers are considering abandoning the primary AC grid for a primarily HVDC electrical distribution system. Standards are currently being developed for future all-HVDC networks. Like AC grids, HVDC networks must be regulated with high precision.

[0014] With the implementation of an HVDC network, each of the above-mentioned conventional generators is associated with an AC-to-DC converter that allows the AC voltage from the generator to be changed to the DC voltage of the HVDC network. The high-voltage battery is connected to the HVDC network via the DC-to-DC converter, which makes it possible to match the voltage of the battery (which is inherently variable and depends on its state of charge) with the fixed and regulated voltage of the HVDC network.

[0015] AC networks have a number of disadvantages. Firstly, modern main AC generators are driven by the aircraft's propulsion engines and therefore cannot be connected in parallel, as synchronisation is not possible unless a speed control system is implemented via a CSD type hydraulic converter.

[0016] The main generators and associated AC network are sized to account for potential propulsion engine failures. Oversizing the generators means they are underutilized. For example, for an aircraft with two engines and two generators per engine, the main generators are used at approximately 30% of their nominal capacity during the cruise phase of flight. The mass of the generators and the mass of the wiring associated with each generator are proportional to the installed power required to achieve their nominal capacity. In other words, power generation is highly unfavorable in terms of onboard mass.

[0017] Likewise, the presence of a RAT used only as a backup is also detrimental to the onboard quality. The RAT has a very low power density of approximately 0.3 kW / kg. In addition, the RAT does not address all operating situations in backup mode. For example, when the aircraft is at low speed (e.g. during the approach and landing phases), the RAT is no longer able to provide its backup function because the aircraft speed is too low. Furthermore, in the event of the loss of both propulsion engines and the deployment of the RAT, power generation is interrupted during the time it takes to deploy the RAT and start its generator. The use of the RAT requires hydraulic and electrical energy reserves, such as batteries to allow the hydraulic and electrical systems necessary for safe flight operation, in particular to power the aircraft's brakes.

[0018] The presence of an APU also negatively impacts the aircraft's onboard quality. Before the propulsion engines driving the main generators are started, the APU is first used on the ground. APUs use kerosene and are highly polluting. At some airports equipped with ground-based power services, APU use is strictly regulated or even prohibited, making their practicality on aircraft highly questionable. Onboard APUs are only installed during critical phases, such as the loss of both engines in flight, which could occur, for example, in the event of a simultaneous bird strike in both engines during takeoff. Because the RAT allows power to be supplied to only a very limited number of devices, rapid APU startup in such extreme situations can keep more devices operational, improving pilot comfort and allowing the aircraft to return to the ground in complete safety compared to RAT- or battery-based operation. Some aircraft manufacturers are also working to replace APUs with systems that do not emit CO2 and toxic gases, such as fuel cells that supply hydrogen produced by electrolysis. However, this solution has been difficult to implement due to the challenges associated with installing such devices on aircraft and the lack of dedicated hydrogen production and distribution circuits. Specifically, most hydrogen is currently produced from oil-based products.

[0019] Regarding the EPDS, the voltage it transmits must meet very strict aviation standards. These standards define the voltage levels and frequencies to be adhered to, regardless of the operating mode. These standards require, in particular, highly precise voltage regulation. In aircraft using a 400Hz fixed-frequency network, the frequency regulation is approximately 1Hz. Voltage regulation for the 115VAC and 230VAC voltages from the generators is performed by a control module associated with each generator in the generator set and known in the literature by the designation GCU: "Generator Control Unit." In the case of a fixed-frequency network using an IDG, precise regulation requires an extremely precise and therefore expensive CDS.

[0020] Loads powered by the voltage delivered by the EPDS must also adhere to precise regulations. Harmonic suppression, in particular, must remain below standardized templates. Because these templates are so strict, filters must be associated with each load to ensure the network is compatible with the loads it supplies. Tight tolerances often make these filters more complex and heavier. In some cases, a filter can be as heavy as the load it is associated with.

[0021] Finally, the standards to which networks must adhere do not allow loads powered by these networks to return energy to the grid. Consequently, it is impossible to consider recovering lost energy in the growing number of reversible loads, such as motors and engines. Currently, each reversible load must carry onboard means for passively dissipating the regenerated energy in its associated converter.

[0022] HVDC networks also have a number of drawbacks. They address some of the shortcomings of AC networks, particularly by allowing generators to be connected in parallel. This parallel connection allows for increased generator utilization during cruise, thereby reducing the ratio between installed electrical power and the nominal power consumed by the aircraft.

[0023] However, maintaining the AC rotation of the generator and the implementation of the HVDC network requires rectifying the three-phase AC voltage of the generator, and therefore requires carrying an additional on-board converter to rectify the voltage of the generator.

[0024] Furthermore, since most onboard loads operate at AC voltage, the HVDC voltage needs to be converted back to an AC voltage that the loads can use, resulting in a large number of DC-to-AC converters. Given the increasing power requirements of onboard aircraft, all of these converters require additional air cooling systems or liquid circuits, further degrading the aircraft's mass balance. Ultimately, the addition of these numerous converters often degrades the reliability and availability of the aircraft's electrical systems compared to a less complex and more reliable AC electrical architecture.

[0025] Patent application WO 2007 / 113312, filed in the applicant's name, proposes optimizing the overall converter mass by aggregating converters. Specifically, on aircraft, some dedicated converters are used only for short periods, so aggregating their use is advantageous. However, this aggregating also presents certification challenges, as it is necessary to demonstrate that aggregating does not affect the safety of aircraft systems. This constraint is particularly addressed in the D0297 standard. Furthermore, aggregating requires additional systems (such as contactor arrays), which degrades the onboard mass balance.

[0026] Like AC networks, HVDC networks are subject to stringent standards. Loads connected to these networks must incorporate filters to prevent interference from being fed back into them. Again, similar to AC networks, loads must not feed energy back into them. Therefore, regenerative loads must be equipped with a means to dissipate the regenerated energy. Summary of the Invention

[0027] The present invention aims to overcome all or some of the aforementioned problems by proposing a novel electrical architecture comprising an unregulated auxiliary grid capable of receiving energy from any type of device, from the main generator, and from regenerative loads. This auxiliary grid also allows for temporary energy storage. The auxiliary grid acts as a buffer in which energy is stored, particularly due to oversizing of the main generator, and allows for supply to the main grid during certain consumption peaks.

[0028] To this end, the subject of the invention is an electrical architecture for an aircraft comprising:

[0029] a plurality of main generators, each of which is associated with a propulsion engine of the aircraft, each of which is configured to deliver a nominal power,

[0030] a plurality of main grids, each of which is associated with a main generator and operates at a first nominal voltage in a nominal operating mode,

[0031] a single-part auxiliary electrical network operating within a voltage range having a minimum value at least equal to twice the value of said first nominal voltage,

[0032] - an electric energy accumulation device, said electric energy accumulation device being directly connected to said auxiliary network,

[0033] a first electric energy converter arranged between the auxiliary network and a first one of the main networks, thereby allowing energy to be transferred from the first one of the main networks to the auxiliary network, the first electric energy converter being intended to supply electric energy to the electric energy accumulation device in a nominal operating mode,

[0034] a second electric energy converter arranged between the auxiliary grid and a second one of the main grids, thereby allowing energy to be transferred from the auxiliary grid to the second one of the main grids in a nominal operating mode,

[0035] The electric energy accumulation device and the second electric energy converter are configured to allow supplying power to the second one of the main grids, the power being at least equal to half the nominal power of a main one of the main generators.

[0036] The electrical architecture may further include:

[0037] at least one regulated low-voltage DC network, the nominal voltage of which is substantially between 24 V and 30 V, which is separate from the integrated auxiliary network,

[0038] - at least one battery connected to the low-voltage DC network,

[0039] - a third power converter, the third power converter being configured to supply power from a main power grid in the main power grids to the low-voltage DC network,

[0040] A fourth power converter for supplying power to one of the main electrical networks to which the base loads of the aircraft are connected.

[0041] The main electrical network may be regulated and the secondary electrical network is advantageously a DC voltage network whose voltage is set by the electrical energy accumulation device.

[0042] The integrated auxiliary power grid may be configured to operate at a nominal operating voltage having a value that can vary within a ratio from 1 to 3 in a nominal operating mode.

[0043] Advantageously, the nominal power of the first electric energy converter is lower than the nominal power of the second electric energy converter.

[0044] A regenerative load may be connected to the auxiliary grid through a bidirectional converter without passing through the main grid in the main grid.

[0045] At least one generator unit, independent of any propulsion engine of the aircraft, may be connected to the auxiliary electrical network without passing through a main one of the main electrical networks.

[0046] The home cabin grid may be connected to the auxiliary grid via a third power converter without passing through the main grid of the main grids.

[0047] The electrical architecture may include a basic electrical grid for supplying power to the basic loads of the aircraft, and the second electrical energy converter may be capable of supplying power to the basic electrical grid.

[0048] The electrical architecture may include a power distribution system and a control module, wherein the control module is configured to control the auxiliary power grid and exchange information to drive the power converter.

[0049] The first and second electrical energy converters advantageously each comprise a transformer with reinforced insulation.

[0050] The second power converter is advantageously connected to the second main grid via semiconductor-based electronic switches, thereby allowing the integrated auxiliary grid to supply a short-circuit current to loads connected to the second main grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The invention will be better understood and further advantages will become apparent upon reading the detailed description of one embodiment provided by way of example, which description is illustrated by the accompanying drawings in which:

[0052] Figure 1 An example of an electrical architecture suitable for a commercial aircraft according to the present invention is schematically shown;

[0053] Figure 2 A more precise example of an electrical architecture according to the invention applicable to a main AC network is shown;

[0054] Figure 3 and Figure 4 An example of an electrical architecture according to the invention is shown, wherein some devices are redundant. DETAILED DESCRIPTION

[0055] For purposes of clarity, identical elements will be provided with the same reference numbers throughout the drawings.

[0056] Figure 1 An example of an electrical architecture according to the present invention is shown. Figure 1 The electrical architecture of a twin-engine commercial aircraft is shown. Each of the propulsion engines M1 and M2 drives two generators: G1.1 and G1.2 for engine M1, and G2.1 and G2.2 for engine M2. The present invention can be implemented regardless of the number of propulsion engines and the number of generators per engine. The present invention can also be implemented for other types of aircraft, such as rotary-wing aircraft.

[0057] In the example shown, the aircraft also has other generators, such as generator G3, which is driven by the APU and the RAT. These auxiliary (APU) and standby (RAT) generators are not mandatory for the present invention, as will be seen further below. The electrical architecture includes an electrical power distribution system (EPDS) that receives electrical energy from all these generators. A network (also called the main network) is associated with each generator, in particular the generators associated with the propulsion engines, which are referred to as the main generators. Figure 1 The main network not shown in the figure belongs to the EPDS. The EPDS then distributes the energy it receives to the various loads of the aircraft. Figure 1In the diagram, the loads are grouped according to the type of network that supplies them: 115VAC loads, 230VAC loads, 28VDC loads and loads supplied by high voltage direct current (HVDC). These four types of loads are given by way of example only. The invention can be implemented regardless of the number of different network types. Some aircraft may be equipped with only one type of network. Furthermore, the AC network may be of fixed frequency (e.g. 400 Hz) or of variable frequency (e.g. between 400 Hz and 800 Hz). Among the loads, some are considered essential or critical, while others are considered non-essential. Essential loads include any load that is necessary to ensure the correct functioning of the aircraft in the event of a malfunction. Essential loads include, in particular, certain computers and flight controls. Non-essential loads include, in particular, so-called commercial loads that allow services to be provided to passengers on board the cabin. Non-essential loads can be unloaded if necessary.

[0058] Many airports allow aircraft to connect to a ground supply unit, which typically delivers 115V 400Hz. This architecture includes the EXT PWR 1 outlet for connecting the EPDS to the ground supply unit. Modern aircraft equipped with a 230V 400Hz mains network must have an onboard converter to convert the voltage from 115V to 230V. This converter represents unnecessary airborne mass.

[0059] In an aircraft that does not implement the present invention, the generator, EPDS and load are usually carried. This structure is retained in the present invention.

[0060] According to the present invention, the electrical architecture includes a secondary power grid (RES) that supplements the aircraft's primary power grid. The primary power grid is directly powered by the aircraft's main generator. The secondary power grid (RES) is said to be integral. More precisely, the secondary power grid (RES) does not include any contactors for disconnecting itself. The secondary power grid (RES) is formed by integral distribution bars or busbars. The secondary power grid (RES) is considered a non-reconfigurable and unbreakable electrical node. In the event of a fault, devices connected to this network may be disconnected.

[0061] exist Figure 1 In the example shown, the auxiliary power grid RES is a high voltage direct current HVDC network. The present invention can also be implemented using an AC voltage auxiliary power grid.

[0062] The electrical architecture includes an electrical energy accumulation device BAT-HVDC. Any type of electrical energy accumulation device can be implemented in the context of the present invention. Batteries that can store energy in chemical form and output energy in electrical form are of course possible. Instead of or in addition to batteries, any device that can store energy in any physical form (especially electrical, mechanical, thermal) and output energy in electrical form (such as, for example, a supercapacitor or a flywheel) can be implemented. An electrical energy accumulation device that accumulates and transmits energy in the form of AC voltage can be implemented. This type of electrical energy accumulation device is suitable for AC voltage auxiliary power grids.

[0063] The electrical energy storage device BAT-HVDC is directly connected to the auxiliary network without requiring an energy converter or passing through the main grid in the main power grid. In other words, the voltage of the auxiliary power network RES is superimposed on the voltage of the electrical energy storage device BAT-HVDC. In a regulated conventional HVDC network, it is not possible to directly connect batteries to the network. Specifically, the battery voltage fluctuates significantly, depending primarily on its state of charge. An energy converter must be placed between the battery and the conventional network, particularly to match the voltage levels. For example, the voltage of a lithium-ion HVDC battery can typically vary by several hundred volts during operation, for example, between 230V and 500V, depending on its state of charge. Typically, the minimum operating voltage of the auxiliary power network RES is 230V for aircraft equipped with a 115VAC three-phase network, and 460V for aircraft equipped with a 230VAC three-phase network. More generally, the minimum operating voltage of the auxiliary power network RES during nominal operating mode is advantageously at least twice the nominal voltage value of networks AC1 and AC2. Conventional networks implemented in commercial aircraft are regulated. The permitted voltage variation in these networks is approximately 1 volt. In contrast, no specific regulation is performed for the auxiliary power network RES, within which the voltage of the electrical energy storage device BAT-HVDC can vary during nominal operation. The voltage range of the auxiliary power network RES is simply limited to avoid excessive discharge or unacceptable overcharging of the electrical energy storage device BAT-HVDC. For example, the auxiliary power network RES can be configured so that its operating voltage in nominal operating mode (that is, in the absence of any faults) varies within a ratio of 1 to 3.

[0064] The auxiliary power grid (RES) can exchange energy with the EPDS. To this end, the architecture includes two power converters CP1 and CP2, arranged between the auxiliary power grid (RES) and the EPDS. Converter CP1 is configured to transfer energy from one of the main power grids to the auxiliary power grid (RES) in nominal operating mode, and converter CP2 is configured to transfer energy from the auxiliary power grid (RES) to the other of the main power grids. The two converters are separate and can operate simultaneously. One of the main power grids can supply energy to the auxiliary power grid (RES), particularly when the main generator associated with that main power grid is underutilized. During the aircraft's flight, cruise phase, and nominal operation, the main generator is underutilized, meaning that there is almost always available generated power to supply energy to the auxiliary power grid (RES), thereby almost continuously recharging the electrical energy accumulation device (BAT-HVDC). Nominal operating mode is understood to mean operation of the aircraft during its cruise phase in the absence of any faults. Each of generators G1.1, G1.2, G2.1, G2.2, and G3 has the potential to supply energy to the auxiliary power grid (RES). A set of contactors (an example of which is given further below) makes it possible to connect one of the generators to the auxiliary power grid RES. Another of the main networks can receive energy from the auxiliary power grid RES, for example in the event of a consumption peak of a load associated with the other main network, which can occur in nominal operating mode.

[0065] In the electrical architecture, a plurality of auxiliary power grids RES may be provided, each of which is connected to an electric energy accumulation device BAT-HVDC and two converters CP1 and CP2 .

[0066] The architecture includes a control module C for controlling the auxiliary power supply (RES). The control module C drives converters CP1 and CP2 and the electrical energy accumulation device BAT-HVDC. The electrical architecture may also include an overall controller for controlling the entire aircraft electrical architecture. The overall controller drives both the EPDS and the control module C. The control module C and the overall controller may be physically combined within a single, identical computer. Alternatively, for safety reasons, it may be advantageous to separate the functions of the control module C and the overall controller, for example to allow for complete decoupling of the EPDS from the auxiliary power supply (RES).

[0067] If the electrical energy accumulation device BAT-HVDC is a battery, the operation of converter CP1 can closely resemble that of a battery charger suitable for battery technology. Converter CP1 can include one or more contactors at its input on the EPDS side to select the generator to which converter CP1 is connected. Converter CP1 also includes a rectifier transformer, for example, consisting of a transformer separating the main and auxiliary power grids, a diode-based electronic rectifier, and a current regulator for regulating the current on the output side of the auxiliary power grid RES. To ensure adequate isolation of the auxiliary power grid RES from the EPDS, the transformer can have reinforced insulation to prevent undesirable propagation between the regulated voltage of the main grid and the unregulated voltage of the auxiliary power grid RES. The transformer can include a detection device for detecting a loss of isolation between the main and auxiliary power grids, such as described in patent application EP 3499254A1 filed in the applicant's name. Detection of the loss of isolation can then be activated by contactors located at the input of converter CP1. For availability purposes, converter CP1 can have a redundant architecture. Other embodiments of converter CP1 are of course possible within the context of the present invention.

[0068] The converter CP2 is adapted to the voltage of the auxiliary power grid RES, which can supply energy to the one or more main power grids, and one or more voltages of the one or more main power grids. The voltage of the auxiliary power grid RES can be AC ​​or DC, and the voltage of the one or more main power grids can also be AC ​​or DC.

[0069] Converter CP2 may include one or more contactors at the output end on one side of the EPDS to select the main network to which converter CP2 is connected. Converter CP2 may include an electronic inverter stage that makes it possible to generate a voltage compatible with the voltage of the network to which converter CP2 is connected, based on the voltage of the auxiliary power grid RES. Compatible voltage is primarily understood to mean a voltage with the same amplitude, frequency, phase synchronization, and that complies with the standards applied to the main generator. Converter CP2 may include an isolation transformer at the output end that allows complete isolation between the auxiliary power grid RES and the EPDS. In the same manner as converter CP1, the transformer of converter CP2 may have reinforced insulation and a detection device for detecting a loss of isolation between the main power grid and the auxiliary power grid. For the purpose of availability, converter CP2 has an advantageously redundant architecture. In the same manner as converter CP1, other types of implementations can be envisioned for converter CP2.

[0070] For example, when the EPDS includes one or more AC networks, it is advantageous to select an electric energy accumulator BAT-HVDC whose nominal voltage is equal to the voltage rectified directly from the AC network, thereby avoiding the use of the booster of converter CP1. For example, for a 115VAC three-phase network, an electric energy accumulator BAT-HVDC with a nominal voltage of 270VDC can be selected, and for a 230VAC three-phase network, an electric energy accumulator BAT-HVDC with a nominal voltage of 540VDC can be selected.

[0071] Because energy transfer from one of the EPDS networks to the auxiliary power grid (RES) via converter CP1 can occur for much of the flight duration, particularly throughout the cruise phase, converter CP1 can have a lower nominal power rating than converter CP2, which may be required to supply a greater amount of energy during these short durations. For example, in conventional architectures, the main generator is sized to allow for energy generation in the event of a fault (e.g., a short circuit on the load). Between the time the short circuit occurs and the time the protection trips to isolate the short-circuited device, the associated generator must be able to supply the short-circuit current. By implementing the present invention, short-circuit current can be supplied at any time via the auxiliary power grid (RES), in addition to the main generator associated with the faulty device. When the auxiliary power grid (RES) is supplying additional energy, converter CP2 synchronizes with the generator it supports. In other words, implementing the present invention allows limiting oversizing of the main generator by utilizing the auxiliary power grid (RES) for peak power consumption. These peaks utilize converter CP2, which is then sized for this purpose, with, for example, converter CP2's nominal power rating being greater than that of converter CP1.

[0072] In addition to supplying the aircraft's loads with electricity during consumption peaks, the energy of the auxiliary power grid RES can be used for other purposes.

[0073] In the event of a failure of one or more main generators, for example in the event of the loss of one or two propulsion engines of an aircraft, converter CP2 replaces one or more failed generators, as seen from the EPDS. In an intermediate manner between nominal operation and the complete loss of one or more generators, the auxiliary network RES can mitigate the risk of transient heating of the main generators or pumping of the engines driving them. The risk of pumping occurs in particular when the engines are idling, when most of the mechanical power delivered by these engines is used for power generation. Temporal variations in power consumption often occur. Sudden variations in power consumption can cause jumps in engine speed or even cause them to seize. More generally, the auxiliary network RES makes it possible to partially or completely and once-off shut down one of the generators of the main distribution network by supplying the required additional power.

[0074] Some of the aircraft's load (in Figure 1 The auxiliary power grid RES (referred to as "Load 1" to "Load N") is connected to the auxiliary power grid RES without passing through the main power grid. This is particularly beneficial when connecting loads capable of regenerating energy, such as electric motors, such as electric thrust inverters or electric wheel motors. Connecting these types of loads to the auxiliary power grid RES allows them to supply regenerative energy to the auxiliary power grid RES. This energy can be used to recharge the electrical energy accumulation device BAT-HVDC or be transferred via converter CP2 to power other aircraft loads. Implementing an unregulated auxiliary power grid RES allows for easier energy recovery compared to the main power grid, which does not allow the use of regenerative energy.

[0075] Figure 1 The loads shown may include, in particular, the cabin network. This is a network that passengers can use, for example, to recharge their portable electronic devices, phones, or computers. This network implements the so-called household voltage commonly used in homes, for example, 220V 50Hz or 60Hz. Such a network also allows the connection of an oven device for heating meals served on board the aircraft. Such devices powered by household voltage are much lighter than devices specifically adapted for the voltage carried by the aircraft's main network. The cabin network is advantageously powered by the auxiliary power network RES, rather than via the main network. Supplying the cabin network via the auxiliary power network RES makes it possible, in particular, to avoid momentary power outages when a generator in the main network is replaced, particularly when power generation is transferred from the APU to the main generator.

[0076] The electric wheel motors can also be powered by the auxiliary electrical network RES without passing through the main network.The wheel motors of the aircraft allow it to move in electric taxi (e-taxi) mode.

[0077] Typically, in aircraft with a primary AC network and no secondary power supply (RES), most AC loads require a rectifier followed by an inverter to power them. The rectifier (usually designated by the acronym ATRU for Auto-Transformer Rectifier Unit) must be able to deliver all the instantaneous power required to operate the connected loads, thus increasing the mass of the aircraft. Supplying these loads via the secondary power supply (RES) operating in DC current mode eliminates the need for the equally bulky ATRU. The rectifier function is then provided by a converter CP1, which is dimensioned based on average power consumption rather than the maximum power consumed by the loads. The energy accumulation device BAT-HVDC supplies the loads with power during peak consumption periods.

[0078] For electrical architectures that incorporate a secondary power grid (RES) during the design phase, the present invention makes it possible to size the main generator based on the average power consumed by all aircraft loads and the power required to charge the BAT-HVDC power storage device. It is no longer necessary to size the main generator based on the maximum power consumed by the loads, particularly during peak power consumption periods. The BAT-HVDC power storage device and converter CP2 are themselves sized to supply power to the main grid during peak power consumption periods, in addition to the power delivered by the main generator. The present invention can also be implemented in existing electrical architectures, where the main generators are already sized to cover peak power consumption. Modifying this existing electrical architecture by integrating the RES and the BAT-HVDC power storage device into it without modifying the existing generators makes it easy to add additional functionality, such as, in particular, electric taxiing, cabin networking, energy recovery from loads capable of regenerating energy, and the ability to transfer the power supply to loads from one generator to another without any power outages, as described above.

[0079] The generator (in Figure 1 The generators SDC and SAC are connected to the auxiliary power grid RES via specific converters, without passing through the main network. The generator SDC supplies a DC voltage and is connected to the auxiliary power grid RES via a DC to DC converter. This converter is necessary because the voltage of the auxiliary power grid RES is applied by the electric energy accumulation device BAT-HVDC. The DC to DC converter makes it possible to match the output voltage of the generator SDC with the voltage of the auxiliary power grid RES. The generator SAC supplies a single-phase or multi-phase AC voltage and is connected to the auxiliary power grid RES via an AC to DC converter. The generators SDC and SAC are driven by a control module C. Any type of generator can be connected to the auxiliary power grid RES. The generator can be an electric motor driven by an internal combustion engine. In particular, other types of generators based on renewable energy (such as fuel cells or photovoltaic panels) can be connected to the auxiliary power grid RES. It is advantageous to connect a generator independent of the aircraft's propulsion engine to the auxiliary power grid RES.

[0080] The auxiliary power grid RES can also receive energy via a ground supply outlet EXTPWR 2 adapted for ground supply units located at airports. The ground supply outlet EXT PWR 2 connects to the auxiliary power grid RES without passing through the aircraft's main electrical network. For example, connecting to the ground supply unit via the EXT PWR 2 outlet allows for rapid recharging of the electrical energy accumulator BAT-HVDC during layovers. Implementing an auxiliary power grid RES with an AC voltage of 115V, 400Hz allows the use of commonly installed ground supply units. For HVDC auxiliary power grids RES, ground supply units suitable for this HVDC voltage can be provided.

[0081] The generators already present in the aircraft (such as the APU and RAT) can be connected directly to the auxiliary power grid RES without having to connect them directly to the main grid. Specifically, during nominal operation, the APU and RAT are rarely used. The APU is actually only used on the ground, while the RAT is only used as a backup. By connecting them to the auxiliary power grid RES, they can be used in a more rational way (especially for the APU), in particular to recharge the electric energy storage device BAT-HVDC during certain flight phases. If the charging state of the electric energy storage device BAT-HVDC allows, the electrical functions performed on the ground by the APU and the RAT as a backup can be provided by the electric energy storage device BAT-HVDC via the auxiliary power grid RES. Therefore, the implementation of the present invention makes it possible to eliminate the generators of the RAT and APU or at least one of the two.

[0082] The generator connected to the auxiliary grid RES acts as a current source injecting current into the electric energy accumulation device BAT-HVDC. The load connected to the auxiliary grid RES also acts as a current source drawing power from the electric energy accumulation device BAT-HVDC.

[0083] The control module C for controlling the auxiliary power supply RES retrieves information from the EPDS via the master controller over a secure communication bus. This information includes, in particular, information useful for managing the auxiliary power supply RES, such as information on the capacity and availability of the various generators connected to the EPDS, or the configuration status of the various elements of the EDPS, such as the status of the various contactors of the EDPS.

[0084] The communication bus makes it possible to exchange other information useful for the operation of the auxiliary power grid RES, such as the voltage and frequency characteristics of the generator outputs connected to the EPDS, so as to allow the converter CP2 to inject the correct voltage in terms of amplitude, frequency and phase into the regulated distribution network of the EPDS to which it is connected. Via this communication bus, the master controller can request the EPDS to modify its configuration, in particular the state of the contactors belonging to the EPDS.

[0085] The control module C communicates with the electrical energy accumulation device BAT-HVDC via a communication bus to determine its state of charge (SOC) and state of health (SOH). The control module C also communicates with the converters CP1 and CP2 via another communication bus to exchange power and voltage setpoints.

[0086] When the generators, in particular the generators SDC and SAC, and when the loads are connected to the secondary electrical network RES without passing through the main electrical network of the aircraft, the control module C is able to communicate with these various devices via a communication bus.

[0087] The control module C and the overall controller can be implemented using modular computers commonly used in the aviation sector. This type of computer is referred to in the literature as "Integrated Modular Avionics," or IMA for short. Other control architectures for controlling the auxiliary power supply network RES and the devices connected to it can be implemented within the context of the present invention.

[0088] Figure 2 An example of an electrical architecture according to the present invention is shown for use with two regulated voltage main AC networks AC1 and AC2. This architecture includes two main generators GEN1 and GEN2. This architecture can also be powered by a ground supply unit, the outlet of which is labeled EXT PWR 1. In nominal operating mode, generator GEN1 supplies power to network AC1 via contactor C1, and generator GEN2 supplies power to network AC2 via contactor C2. Ground supply outlet EXT PWR 1 can be connected to network AC1 via contactors Cext and C11, and to network AC2 via contactors Cext and C21. The main AC network is powered by either network AC1 or network AC2 via contactor set Cace. The main AC network, in particular, allows for powering essential loads requiring AC mains voltage. In flight, in the event of a loss of main generators GEN1 and GEN2, the main AC network is powered by the ram air turbine (RAT).

[0089] Figure 2 The electrical architecture also includes multiple regulated low-voltage DC networks with a nominal voltage of 28V. In practice, voltage regulation allows the nominal voltage of these networks to vary generally between 24V and 30V. Commercial aircraft with two main AC networks AC1 and AC2 and a network, Basic AC, have two associated DC networks DC1 and DC2, respectively, and a network, Basic DC, designed to supply essential loads with a low voltage of 28V. Networks DC1 and DC2, for their part, allow for the supply of non-essential loads that can be removed without compromising flight safety. The DC networks DC1, DC2, and Basic DC are supplied by the AC networks AC1, AC2, and Basic AC, respectively, via AC-to-DC converters (respectively, TRU 1, TRU 2, and TRU ESS, such as transformers associated with rectifiers, often designated by the acronym TRU (Transformer Rectifier Unit)) and contactors (respectively, Cdc1, Cdc2, and Cdce). Regulators and filters may be associated with each TRU to achieve a DC voltage that complies with prescribed aviation standards.

[0090] The three DC networks DC1, DC2, and the base DC are connected to batteries BAT1 and BAT2, which themselves are also low-voltage, via a battery network BAT DC and contactors (Cdc11, Cdc21, and Cdc11, respectively). Associated with each of the two batteries BAT1 and BAT2, the architecture can include a DC network (HOT DC1 and HOT DC2, respectively) connected to its respective battery BAT1 and BAT2 without any contactors. One of the batteries (e.g., battery BAT1) can supply power to the network base AC via a DC-to-AC converter INV STAT, particularly in the event of a failure of the main generators GEN1 and GEN2. The converter INV STAT is dimensioned to supply only some of the base loads supplied by the network base AC. Its nominal power is much lower than that of one of the main generators, typically a few kilowatts. When not supplied by the converter TRU ESS, the other battery BAT2 can supply power to the network base DC.

[0091] Figure 2 The architecture comprises an auxiliary power grid (RES), two converters CP1 and CP2, and an energy accumulation device BAT-HVDC directly connected to the auxiliary power grid (RES). Unlike converter INV STAT, converter CP2 is dimensioned to supply both essential loads connected to the network's base AC voltage and non-essential loads via networks AC1 and AC2. The auxiliary power grid (RES) is separate from the aforementioned low-voltage DC grid. It also includes possible regenerative loads, which are connected to the auxiliary power grid (RES) via DC-to-AC converters. Finally, it includes a control module C, the connections of which are not shown. Converter CP2 can be connected to network AC1 via contactors K2.1 and C11, to network AC2 via contactors K2.1 and C21, and to the base AC voltage via contactors K2.2 and Ce. Converter CP1 can be connected to network AC1 via contactor K1.1 and to network AC2 via contactor K1.2.

[0092] Regulated AC networks AC1, AC2 (basic AC) and regulated DC networks DC1, DC2 (basic DC) are typically already implemented in commercial aircraft. A secondary power grid RES, two converters CP1, CP2, and a BAT-HVDC power storage device can be added to these already implemented regulated networks. Alternatively, the regulated DC networks, particularly networks DC1 and DC2, can be eliminated by connecting loads typically supplied by these regulated networks to the new secondary power grid RES.

[0093] In nominal operating mode and during flight, both generators GEN1 and GEN2 are in operation. They each supply one of the networks (AC1 and AC2, respectively). In conventional architectures, the main generators GEN1 and GEN2 are oversized to power all aircraft loads. This oversizing must account for peak consumption during all flight phases in nominal operating mode (i.e., in the absence of any faults). Implementing a secondary power grid RES allows the energy storage device BAT-HVDC to supply the required power during peak consumption periods. The nominal power of the main generators GEN1 and GEN2 can then be reduced, and they can be sized based on the average power consumed by all aircraft loads, rather than the maximum power consumed during peak consumption periods. During sizing, fault scenarios must also be considered, particularly engine failures and, consequently, the failure of one of the generators GEN1 or GEN2. Excess capacity from the generators GEN1 and GEN2 can be used to charge the energy storage device BAT-HVDC. To this end, converter CP1 draws energy from network AC1 by closing contactor K1.1 or from network AC2 by closing contactor K1.2. Converter CP1 can be redundant and can then draw energy from both networks AC1 and AC2 simultaneously. In the event of a failure in one of the modules of converter CP1, the other module can continue to draw energy from either network AC1 or AC2.

[0094] During flight, if a generator (e.g., generator GEN1) is lost, the auxiliary power grid RES can supply power to the main grid AC1 via converter CP2 and contactors K2.1 and C11. During this fault, energy can still be drawn from the main grid AC2 to supply power to the auxiliary power grid RES via converter CP1 and contactor K1.2. In other words, even if a generator is lost, the power accumulator BAT-HVDC can be prevented from discharging, and the auxiliary power grid RES can still be used to supply power to the main grid.

[0095] More generally, the BAT-HVDC electrical energy storage device can be continuously recharged throughout the flight. As mentioned above, the main generators GEN1 and GEN2 are oversized to account for the possibility of a generator failure. During nominal operation (i.e., in the absence of any faults), the main generators GEN1 and GEN2 are underloaded. Approximately 30% and 40% of their available power are utilized, leaving 60% and 70% of the power available on each generator, respectively. This is largely sufficient to rapidly recharge the BAT-HVDC electrical energy storage device during nominal operation, and especially during cruise.

[0096] In the event of an engine loss, the remaining generator must take over the lost generator's load. Consequently, it may be loaded to between 60% and 80%. In this case, the recharging capacity of the BAT-HVDC power storage device can still be between 20% and 40% of the remaining generator's power. It is advantageous to dimension the auxiliary network RES and the BAT-HVDC power storage device so that they can replace the main generator in the event of its loss.

[0097] In the event of a loss of the second generator GEN2, contactor C21 closes to supply power to the network AC2 via converter CP2. Power can also be supplied to the network's basic AC supply via converter CP2 and contactors K2.2 and Ce. The electrical energy storage device BAT-HVDC can be dimensioned to eliminate the need for a RAT. Specifically, as described above, in the event of a generator failure, no energy can be drawn from the electrical energy storage device BAT-HVDC. Therefore, even if the first generator has already failed, the energy contained in the electrical energy storage device BAT-HVDC is available in the event of a second generator failure.

[0098] In the event of a fault in a load connected to the main network (resulting in a short circuit in the load), the transient overconsumption on the main network in question can be covered by the auxiliary network RES via converter CP2. This overconsumption occurs between the occurrence of the short circuit and the tripping of the protection circuit isolating the load from the main network in question. In this fault scenario, the energy provided by the auxiliary network RES allows the current draw at the main generator supplying power to the main network in question to be limited, and also limits the risk of overvoltage in the main network when the load is isolated. In particular, managing rapid energy production changes in the main generator is difficult. To facilitate the rapid provision of energy from the auxiliary network RES, converter CP2 is connected to the main networks AC1 and / or AC2 and / or the primary AC in question via semiconductor-based electronic switches, which typically change state much faster than electromechanical contactors. Among the electronic switches, insulated gate field-effect transistors (IGBTs and thyristors) are particularly suitable. To isolate the auxiliary network RES from the main network, a normally closed electromechanical isolating switch can be placed in series with the electronic switch.

[0099] When the aircraft is on the ground, the electrical energy storage device BAT-HVDC can also be recharged via one of the networks AC1 or AC2 by closing contactors K1.1 or K1.2, from a ground supply unit connected to the ground supply outlet EXT PWR 1. If the outlet EXT PWR 2 is present and a suitable ground supply unit is available, the electrical energy storage device BAT-HVDC can also be recharged via the ground supply outlet EXT PWR 2.

[0100] The wheel motors of the aircraft used to move the aircraft in electric taxiing mode can be powered by the auxiliary power grid RES. During nominal operation, the electric energy accumulation device BAT-HVDC supplies power to the wheel motors. In the event of a failure or discharge of the electric energy accumulation device BAT-HVDC, the electric taxiing function can still be provided by the main generators GEN1 and GEN2 driven by the propulsion engines. The generators GEN1 and GEN2 supply power to the networks AC1 and AC2, which in turn supply power to the auxiliary power grid RES through the converter CP1, thereby making it possible to supply power to the wheel motors. In other words, even in the event of a failure of the main devices connected to the auxiliary power grid RES (in particular the electric energy accumulation device BAT-HVDC), the electric taxiing function is still available.

[0101] Unlike the 28V batteries BAT1 and BAT2 (which, in standby mode, are designed to power 28VDC loads and some essential loads via the converter INV STAT), the BAT-HVDC electrical energy accumulator is capable of temporarily powering any type of load and delivering significant instantaneous power throughout all phases of flight. The BAT-HVDC electrical energy accumulator is advantageously dimensioned to deliver instantaneous power of the same order of magnitude as the individual main motors in the main generators GEN1 or GEN2, typically between half and one and a half times the instantaneous power of the respective main generators in the main generators GEN1 or GEN2. The duration for which the BAT-HVDC electrical energy accumulator can supply this power depends primarily on its energy content and, therefore, its size, which is designed based on the loads that can be powered. To optimize the quality of the BAT-HVDC electrical energy accumulator and the converter associated with the auxiliary network RES, it is advantageous to maximize the number of loads that can be powered by the auxiliary network RES and to utilize it during all phases of the aircraft's flight. Unlike the 28 VDC battery, which is essentially intended for use in backup mode, it is advantageous to use the auxiliary network RES and the electrical energy accumulation device BAT-HVDC during all operating phases on the ground and in flight and to allow energy to be provided in nominal mode and in backup mode.

[0102] Figure 3An example of an electrical architecture according to the present invention is shown, in which converters CP1 and CP2 are redundant. The electrical energy accumulation device BAT-HVDC is also redundant. Within the context of the present invention, it is of course possible for only one of converters CP1 or CP2 to be redundant, or for only the electrical energy accumulation device BAT-HVDC to be redundant. Figure 3 The auxiliary power grid RES shown is a DC network. As an alternative, the auxiliary power grid RES can be an AC network. The converter CP1 includes two modules CP11 and CP12 that can work in parallel to supply power to the auxiliary power grid RES. In this example, the electrical architecture includes two main AC networks AC1 and AC2. The two modules CP11 and CP12 are AC to DC converters. They may be identical. The converter CP2 includes two modules CP21 and CP22 that can work in parallel to draw energy from the auxiliary power grid RES, and both modules CP21 and CP22 supply power to the two networks AC1 and AC2 through a set of contactors. The two modules CP21 and CP22 are DC to AC converters. The electric energy accumulation device BAT-HVDC includes a plurality of accumulation modules (denoted as BAT1 to BATn) that can work in parallel. If one of the accumulation modules fails, it can be disconnected by a dedicated contactor.

[0103] Figure 4 Another example of an electrical architecture according to the present invention is shown, in which converters CP1 and CP2 are redundant. This example includes Figure 3 The redundant electric energy accumulation device BAT-HVDC in Figure 4 In the example shown, the electrical architecture includes two main networks, AC and DC. Network AC is an AC network, and network DC is a DC network. Module CP11 is an AC-to-DC converter, and module CP12 is a DC-to-DC converter. Converter CP2 includes two modules CP21 and CP22 that can operate in parallel to draw energy from the auxiliary power grid (RES) and supply power to each of the main networks, DC and AC, respectively. Module CP21 is a DC-to-DC converter, and module CP22 is a DC-to-AC converter.

Claims

1. An electrical architecture for an aircraft, comprising: a plurality of main generators, each of the plurality of main generators being associated with a propulsion engine of the aircraft, each of the plurality of main generators being configured to deliver a nominal power, a plurality of main grids, each associated with a main generator and operating at a first nominal voltage in a nominal operating mode, an integrated auxiliary power grid operating within a voltage range having a minimum value at least equal to twice the value of the first nominal voltage, an electric energy accumulation device, the electric energy accumulation device being directly connected to the integrated auxiliary power grid, a first electric energy converter, arranged between the integrated auxiliary power grid and a first main power grid of the plurality of main power grids, thereby allowing energy to be transferred from the first main power grid of the plurality of main power grids to the auxiliary power grid, the first electric energy converter supplying electric energy to the electric energy accumulation device in a nominal operating mode, a second electric energy converter, the second electric energy converter being arranged between the integrated auxiliary power grid and a second main power grid of the plurality of main power grids, thereby allowing energy to be transferred from the integrated auxiliary power grid to the second main power grid of the plurality of main power grids in a nominal operating mode, The electric energy accumulation device and the second electric energy converter are configured to allow supplying a power at least equal to half the nominal power of one of the plurality of main generators to the second of the plurality of main grids.

2. The electrical architecture according to claim 1, further comprising: at least one regulated low-voltage DC network, the nominal voltage of the at least one regulated low-voltage DC network being between 24 V and 30 V, the at least one regulated low-voltage DC network being separate from the integrated auxiliary network, at least one battery connected to the at least one regulated low-voltage DC network, a third power converter for supplying power from one of the plurality of main power grids to the at least one regulated low-voltage DC network, A fourth power converter is configured to supply power to a main power grid, to which the basic load of the aircraft is connected, among the plurality of main power grids.

3. The electrical architecture according to claim 1 or 2, wherein: The plurality of main grids are regulated, and wherein the integrated auxiliary grid is a DC voltage network whose voltage is set by the electrical energy accumulation device.

4. The electrical architecture according to claim 3, wherein: The integrated auxiliary power grid is configured to operate at an operating voltage having a value variable within a ratio from 1 to 3 in a nominal operating mode.

5. The electrical architecture of claim 1 , wherein: The nominal power of the first electric energy converter is lower than the nominal power of the second electric energy converter. 6 . The electrical architecture of claim 1 , further comprising a regenerative load connected to the integrated auxiliary grid via a bidirectional converter without passing through one of the plurality of main grids.

7. The electrical architecture of claim 1 , further comprising at least one generator unit, the at least one generator unit being independent of any propulsion engine of the aircraft and connected to the integrated auxiliary power grid without passing through one of the plurality of main power grids.

8. The electrical architecture of claim 1, further comprising a home cabin power grid connected to the integrated auxiliary power grid via a third power converter without passing through one of the plurality of main power grids. 9 . The electrical architecture according to claim 2 , further comprising a primary power grid for supplying power to the primary loads of the aircraft, wherein the second power converter is capable of supplying power to the primary power grid.

10. The electrical architecture according to claim 2 further comprises a power distribution system and a control module, wherein the control module is used to control the integrated auxiliary power grid and exchange information to drive the first power converter, the second power converter and the third power converter.

11. The electrical architecture of claim 1 , wherein: The first power converter and the second power converter each include a transformer with reinforced insulation.

12. The electrical architecture of claim 1, wherein: The second power converter is connected to the second main grid via a semiconductor-based electronic switch, thereby allowing the integrated auxiliary grid to supply a short-circuit current to a load connected to the second main grid.

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