WO2009125013A2

WO2009125013A2 - Electrical network for aircraft

Info

Publication number: WO2009125013A2
Application number: PCT/EP2009/054339
Authority: WO
Inventors: Alain Tardy
Original assignee: Thales
Priority date: 2008-04-09
Filing date: 2009-04-09
Publication date: 2009-10-15
Also published as: FR2930083A1; FR2930083B1; WO2009125013A3

Abstract

The invention relates to an electrical network for an aircraft. The invention is particularly useful for commercial jumbo jets that increasingly comprise onboard electrical devices. The network comprises a main generator (10, 13) providing alternative tension, a unidirectional rectifier (20) providing continuous tension to a continuous bus (21) from the alternative tension, and a plurality of bidirectional converters (22 through 25) for supplying charges. The aircraft, while on the ground, can be supplied by a stack generator (15). According to the invention, the stack generator (15) is connected onto at least one converter (22 through 25) and no longer onto the rectifier (20). The invention enables streamlining of the rectifier (20) and the generator (10, 13).

Description

Electrical network of an aircraft

The invention relates to an electrical network of an aircraft. The invention finds particular utility for large commercial aircraft that increasingly include onboard electrical equipment. This equipment is very varied in nature and its energy consumption is very variable over time. For example, the internal air conditioning and lighting systems are in almost continuous operation, so redundant safety systems such as steering controls are used only exceptionally.

Generally, the aircraft has three-phase electrical generators to supply all the electrical equipment on board called loads thereafter. These generators deliver for example a voltage of 115 V at a frequency of 400 Hz to an AC network of the aircraft. On board an aircraft, there is for example one or more main generators, well known in the Anglo-Saxon literature under the name of "main generator". These are rotating electrical machines driven by the engine (s) of the aircraft. There is also an auxiliary generator well known in the Anglo-Saxon literature under the name "auxilaiary power unit" driven by a turbine dedicated to this generator and allowing the power of the aircraft when on the ground. Many airports have fleet generators to directly feed the AC network to avoid using the auxiliary generator.

The aircraft generally has a rectifier for supplying a DC voltage from the AC network to a high-voltage continuous network well known in the English literature as the "high voltage direct current". The various loads of the aircraft are fed by the continuous network through converters. The rectifier must be compatible with the different generators that can supply the alternative network. For example, park generators are generally not very tolerant of disturbances rejected by the alternative network and in particular by the rectifier. International standards such as for example MIL STD 704 or ABD 100 define a range in which the network voltage must evolve, a maximum harmonic rate and a maximum imbalance between network phases. This compatibility between the fleet generators and the alternative network of the aircraft is binding for the network and in particular for the rectifier.

The invention seeks to release the aircraft from these constraints by proposing to no longer provide the connection of the park generators directly on the alternative network powered by the onboard generators.

To achieve this goal, the invention proposes to use one or more converters intended to supply, in particular in flight, charges of the aircraft in AC voltage to connect a park generator. For this purpose, the subject of the invention is an electrical network of an aircraft comprising:

At least one generator delivering an alternating voltage,

A unidirectional rectifier supplying a direct voltage to a DC bus from the AC voltage; a plurality of bidirectional converters comprising two connection points, each bidirectional converter being connected at its first point of connection to the DC bus and connectable to its second point of connection to a load of the aircraft for powering it, • connection means of a park group intended to supply electrical energy to the aircraft when it is on the ground, characterized in that that the connection means of the park group are located at the second connection point of at least one bidirectional converters.

The invention simplifies the various equipment connected to the AC network including the rectifier and the generator or generators for which we can tolerate a lower quality level, in terms of disturbance. The invention also makes it possible to reduce the mass of filtering components associated with the rectifier by accepting a higher current harmonic ratio. The invention also makes it possible to increase the frequency of the voltage delivered by the generator or generators, this frequency being no longer constrained by that of elements external to the aircraft such as the park group. By increasing the frequency of the generator, we can reduce the mass. The invention will be better understood and other advantages will appear on reading the detailed description of an embodiment given by way of example, a description illustrated by the accompanying drawing in which: FIG. 1 represents an electrical diagram of FIG. a network installed on board an aircraft; FIG. 2 represents an alternative embodiment of the diagram of FIG. 1; FIG. 3 diagrammatically represents an exemplary embodiment of a converter implemented in one of the diagrams of the preceding figures.

For the sake of clarity, the same elements will bear the same references in the different figures.

FIG. 1 schematically represents various electrical equipment on board an aircraft, in particular a wide-body commercial aircraft. A main generator 10 denoted MG is driven by one of the engines of the aircraft. The generator 10 operates when the engines of the aircraft operate and delivers for example a voltage of 115 V at a frequency of 400 Hz to an AC network 11 of the aircraft. Disconnection means 12 for opening the link connecting the generator 10 to the network 11. An auxiliary generator 13, APU noted, is driven by a turbine dedicated to the generator 13 to supply the AC network 11 the voltage of 115 V. same, means of disconnection 14 for opening the link connecting the auxiliary generator 13 to the network 11. The turbine operates using the fuel of the aircraft and is implemented when the aircraft is on the ground. In large airports, the generator 13 and its associated turbine may remain stationary and the energy required for the aircraft may be provided by a fleet group 15 connected to the aircraft. This park group 15 is for example installed near the aircraft on the ground by means of a truck.

On board the aircraft, is also installed a rectifier 20 connected to the AC network 1 1 and for delivering a DC voltage to a high voltage DC network 21 noted HVDC according to an abbreviation for: "High Voltage Direct Curent". It can be tolerated that the rectifier 20 rejects on the alternative network 1 1 disturbances greater than those authorized by the standards mentioned above since, according to the invention, no connection means of a park group is provided on the alternative network 1 1. The rectifier 20 is unidirectional. It can be realized by means of a simple bridge of diodes. The continuous network 21 supplies several energy converters

22 to 25 each for supplying a load, respectively 26 to 29 via a connection which can be interrupted by a switch, respectively 30 to 33. The representation of Figure 1 is schematic. In practice, a load can be fed by several converters or a converter can supply several loads. Some charges can be supplied with DC voltage and the associated converter then converts the voltage of the DC bus 21 into a voltage that can be used by the load in question. In a jumbo jet, there are many charges using an AC voltage of 1 15 V at a frequency of 400 Hz. These are, for example, charges 28 and 29 shown in FIG. To power these loads, the converters 24 and 25 are inverters. Known inverters have the particularity of being reversible and rejecting little disturbance when used in rectifier. The aircraft further comprises connection means 35 of a park group and according to the invention, the connecting means 35 are connected to at least one of the converters. More specifically, the converters 24 and 25 each have a connection point, respectively 36 and 37, to the DC bus 21, and a connection point respectively 38 and 39 to a load of the aircraft. In the example shown, the connection means 35 are connected to the points 38 and 39 and make it possible to connect the park group 15 to either one or both converters 24 and 25. When the park group is connected to the airplane, the DC bus 21 receives energy through one or both converters 24 and 25. It should be noted that the park group can feed directly some loads of the aircraft, for example the load 29 as shown in FIG. 1, without passing the energy either through one of the converters 22 to 25 or through the rectifier 20.

FIG. 2 represents an embodiment variant in which several converters 41 to 45 form a common resource. Each converter can be assigned in real time to different loads 26 to 29 according to the instantaneous need of each load 26 to 29 and depending on the availability of each of the converters 41 to 45. For this purpose, the electrical network comprises means of turnout 50 to vary the association between converters 41 to 45 and loads 26 to 29. The combination of converters 41 to 45 and loads 26 to 29 is based on the instantaneous power requirement and the instantaneous control mode. the load associated with it. The mode of control of the load depends essentially on the type of load. By way of example commonly used in an aircraft, mention may be made of speed, torque or position regulation, anti-icing or de-icing, constant power operation and various engine control strategies (defluxing, control with or without sensor).

The switching means 50 comprise for example electrically controlled switches for associating each converter with all the loads that are compatible. Compatible means that several loads can operate by means of a common supply, for example a voltage of 115 V at a frequency of 400 Hz. Similarly, the switching means 50 make it possible to vary the association between the park group 15 and one of several converters 43, 44 or 45. Converters for delivering the same power supply form a group whose members are interchangeable. The different members of a group are advantageously identical. This reduces conversion costs by standardizing their production and simplifies maintenance by keeping only one type of converter in stock.

The group is reconfigurable according to the instantaneous need for loads that can be powered by this group. It is not necessary to have a converter dedicated to each load. Indeed, the charges do not all work simultaneously. The number of converters of the same group is defined according to the instantaneous maximum power that all the loads associated with a group can consume. This power is lower than the addition of the maximum powers of each load. The switching means therefore make it possible to reduce the number of on-board converters and therefore the mass of these converters. In addition, reconfiguration improves the availability of loads. Indeed, in case of failure of a converter, another converter of the same group can immediately take over to feed the load. Certain critical loads such as for example steering controls can thus operate with a secure power supply without requiring the redundancy of a converter only dedicated to these commands. The set of converters of the same group then forms a common resource capable of supplying a group of loads. Within the same common resource, the different converters that compose it are undifferentiated.

FIG. 3 is a schematic and simplified representation of an exemplary embodiment of a converter 22 to 25 or 41 to 45. The converter comprises two terminals 50 and 51, the terminal 50 being connected to the positive pole of the continuous network 21 and the terminal 51 being connected to the positive negative pole of the continuous network 21. Between the terminals 50 and 51, the converter comprises three branches 52, 53 and 54 each comprising two electronic switches, T521 and T522 for the branch 52, T531 and T532 for the branch 53 and , T541 and T542 for the branch 54. In each branch 52, 53 and 54 the two switches are connected in series and a diode is connected in parallel with each switch. The reference of the diode is D followed by the digital part of the mark of the switch, for example the diode D 521 is connected across the terminals of the switch T 521. Each diode is connected antiparallel to the direction of the current flowing in. each switch of the positive terminal 50 to the negative terminal 51. The switches are for example all identical and bipolar transistor type insulated gate well known in the English literature under the acronym IGBT for: "Insulated Gate Bipolar Transistor". In each branch 52, 53 and 54, at the common point of the two switches, a self, respectively L52, L53 and L54 is connected by its first terminal. A second terminal, 56, 57 and 58 of each inductor, respectively L52, L53 and L54, allows the converter to supply a three-phase load. Capacitors C521 to C542 are connected between one of the terminals 56, 57 and 58 and one of the terminals 50 and 51. When the electrical energy is supplied to the converter by the continuous network 21, the converter operates as a voltage inverter. On the other hand, when the electrical energy is supplied alternately between the terminals 56, 57 and 58, for example by the park group 15, the converter operates as a current rectifier. To rectify the current supplied by the park group 15, it could have implemented a simpler rectifier, for example a diode bridge. But this type of rectifier would have required the use of a transformer or autotransformer to raise the voltage supplied by the park group 15 (1 15V three-phase) to reach the voltage (540V) of the DC bus 21. On the contrary the operation from the converter to a current rectifier makes it possible to raise the voltage without a transformer.

Claims

An electrical network of an aircraft comprising:

At least one generator (10, 13) delivering an alternating voltage,

A unidirectional rectifier (20) supplying a DC voltage to a DC bus (21) from the AC voltage; a plurality of bidirectional converters (22 to 25; 41 to 45) having two connection points (36 to 39); each bidirectional converter (22 to 25; 41 to 45) being connected at its first connection point (36, 37) to the DC bus (21) and connectable at its second connection point (38, 39) to a load (28, 29) of the aircraft to power it,

Connecting means (35) for a park group (15) intended to supply electric power to the aircraft when it is on the ground, characterized in that the connecting means (35) of the group of park (15) are located at the second connection point (38, 39) of at least one bidirectional converter (22 to 25; 41 to 45).

2. Electrical network according to claim 1, characterized in that the bidirectional converter (22 to 25; 41 to 45) to which are connected the connection means (35) of a park group (15) can supply directly, in its second connection point (38, 39), a load (29) of the aircraft,

3. Electrical network according to claim 2, characterized in that the load (29) which can be directly supplied by the park group (15) operates at an alternating voltage of 1 15 V at a frequency of 400 Hz.

4. Electrical network according to one of the preceding claims, characterized in that the generator (10, 13) is driven either by a motor of the aircraft or by a turbine of the aircraft, turbine dedicated to the generator (13).

5. Electrical network according to one of the preceding claims, characterized in that it comprises switching means (50) for varying the association between converters (41 to 45) and charges (26 to 29).

6. Grid according to claim 5, characterized in that the combination between converters (41 to 45) and loads (26 to 29) can vary in real time according to the instantaneous need of each load (26 to 29) and the availability of converters (41 to 45).

7. Electrical network according to any one of claims 5 or 6, characterized in that the switching means (50) allow to vary the association between the park group (15) and one of several converters (43, 44, 45).