Hybrid propulsion architecture and aircraft containing such an architecture

The invention relates to a hybrid propulsion architecture (100) for an aircraft, comprising: —a first source (102) of a first energy type, —second sources (104) of a second energy type different from the first energy type, —electrical propulsion systems (106), —an electric power supply network (118) connecting the first and second sources (102, 104) to the electrical propulsion systems, such that each electrical propulsion system is powered by the first source and by one of the second sources, the architecture being characterised in that it further comprises: —means for segregating (120) the electrical propulsion systems, which means are arranged in the electric power supply network and configured to impose a direction of flow of the electric power from the first source to the electrical propulsion systems.

TECHNICAL FIELD

The invention concerns a hybrid propulsion architecture and a multi-rotor vertical take-off and landing (VTOL) aircraft, such as a dual-rotor counter-rotating quadricopter, comprising such a hybrid propulsion architecture.

PRIOR ART

The prior art comprises, in particular, the documents FR-A1-3 079 210, EP-A2-2 040 370 and US-A1-2016/016670. The document FR-A1-3 079 210 describes a hybrid propulsion architecture that comprises a first source of a first type of energy, second sources of a second type of energy, electrical propulsion systems and an electrical energy supply network that connects the assembly.

In a known way, a hybrid propulsion architecture is an architecture which uses several energy sources of different type, for example electric-thermal and electrochemical, to feed propulsion systems, and therefore which uses several energy sources of different type for each propulsion channel.

A hybrid propulsion architecture is known, in which there are as many energy sources of each type as there are propulsion channels.

As shown inFIG.1, the architecture10comprises a plurality of propulsion channels18, of which three are shown, each propulsion channel18comprising a first source12of a first type of energy, a second source14of a second type of energy, different from the first type of energy, and one or a plurality of charges16. The first and second sources12,14are separate between each propulsion channel18. In this architecture10, there are therefore as many first sources12, as second sources14, as there are propulsion channels18.

However, this architecture is costly, since it integrates a large number of sources.

In order to reduce the cost and mass of the architecture, it has been proposed to reduce the number of sources, for example by integrating only one source of a first type of energy into the architecture.

As shown inFIG.2, the architecture20comprises a single first source22of a first type of energy. Each propulsion channel28comprises the first source22, a second source24of a second type of energy, different from the first type of energy, and one or a plurality of charges26. The second sources24are distinct between the different propulsion channels28, while the first source22is common to all the propulsion channels28. Thus, in this architecture20, there are as many second sources24, as there are propulsion channels28, but only one first source22that feeds all the propulsion channels28.

However, in such an architecture, there is a common point P between the different propulsion channels, which can propagate a fault from one propulsion channel to another propulsion channel, and thus generate the loss of several propulsion channels following a single failure. For example, a short circuit on one of the charges can propagate to the other charges in the architecture.

In order to solve this problem, it was proposed to integrate the common point between the different propulsion channels to the first source of the first type of energy. Thus, the first source does not propagate a fault from one propulsion channel to another propulsion channel.

As shown inFIG.3, the architecture30comprises a single first source32of a first type of energy, which incorporates the common point between the different propulsion channels38. Each propulsion channel38comprises the first source32, a second source34of a second type of energy, different from the first type of energy, and one or a plurality of charges36. The second sources34are distinct between the different propulsion channels38, while the first source32is common to all the propulsion channels38. Thus, in this architecture30, there are as many second sources34, as there are propulsion channels38, but only one first source32that feeds all propulsion channels38.

However, in this architecture, the design of the first source is constrained, both in terms of cost and complexity.

In addition, the technological solutions allowing to realise a decoupling of the propulsion channels within the first source are currently poorly mastered, and some modes of malfunction are not resolved. For example, one solution currently proposed is to use a permanent magnet alternator with three isolated outputs, thus allowing three propulsion channels to be powered. However, the design of such an alternator does not allow for independence of the outputs, especially in the event of a fault. Thus, a short circuit on one propulsion channel can propagate to the other propulsion channels.

In addition, this architecture lacks flexibility in the power distribution. Although the alternator is rated for a power of 300 kW, each output is rated for a power of 100 kW. Thus, the electrical system is unable to provide more than 100 kW of power to a propulsion channel, even if the total consumption of the electrical system is less than 300 kW.

To overcome this drawback, it would be necessary to oversize the alternator. For example, in order to provide a power of 150 kW on two of the three outputs, and a zero power of 0 kW on the last output (reconfiguration of the electrical system, following a fault for example), i.e., a total power of 300 kW, it is necessary to size the alternator for a total power of 450 kW, which has an impact on its mass of about 50%.

The purpose of the invention is to provide a solution to remedy at least some of these drawbacks.

SUMMARY OF THE INVENTION

It is an objective of the invention to be able to reduce the number of sources of the hybrid propulsion architecture, by creating common points through which electrical energy can flow from a single first source of a first type of energy towards different charges, while ensuring non-propagation of defects on the charges through these common points.

To this end, the invention relates to a hybrid propulsion architecture for an aircraft, comprising:a first source, of a first type, of electrical energy,a plurality of second sources, of a second type, of electrical energy, said second type being different from said first type,a plurality of electrical propulsion systems,an electrical energy supply network connecting said first source and said second sources to said electrical propulsion systems such that each electrical propulsion system is powered by said first source and by one of said second sources,propulsion channels, each propulsion channel comprising said first source, one of said second sources, one of said electrical propulsion systems, and a portion of the electrical energy supply network,said architecture being characterised in that it further comprises:means for segregating said electrical propulsion systems, said segregation means being arranged on said electrical energy supply network and configured to impose a direction of flow of electric power from said first source to said electrical propulsion systems so that said propulsion channels are segregated.

The architecture according to the invention allows the number of energy sources to be reduced, thus reducing the costs and the total mass of the architecture.

In addition, the first energy source is simplified compared to the prior art, and the number of its components is reduced, which increases the reliability of the architecture and reduces its costs.

A propulsion channel comprises the first source, a second source, an electrical propulsion system (also known as a charge) and a portion of the electrical energy supply network between these different elements of the architecture.

The segregation means allow the segregation of the propulsion channels. Thus, the architecture according to the invention is advantageously tolerant to a single failure.

According to the invention, the flux of electrical energy are forced to be unidirectional in the propulsion channels, so as to avoid the propagation of failures between the different propulsion channels. The electrical energy is forced to transit from the common point towards the charges, but cannot transit from the charges to the common point.

According to one embodiment, the first energy source may be an electrical-thermal generation source, and the second energy sources may be electrochemical storage sources.

The architecture according to the invention thus allows a plurality of propulsion channels to be powered, from a plurality of electrochemical storage sources and a single electrical-thermal generation source providing only a single power channel.

The architecture according to the invention allows the plurality of propulsion channels to be powered simultaneously, ensuring that no single failure can generate the loss of more than one propulsion channel.

The architecture according to the invention also allows an automatic distribution of the electric power of the electrical-thermal generation source, without a communication channel connecting the different propulsion channels and the electrical-thermal generation source.

The electrical energy supply network may be a High Voltage Direct Current (HVDC) network. In this case, the segregation means may comprise diodes.

The architecture according to the invention may comprise power electronic converters connected to the electrical energy supply network. Advantageously, the power electronic converters allow to improve the control of the electric power distribution in the different propulsion channels.

According to one embodiment, the power electronic converters are connected between the second sources and the electrical propulsion systems.

According to another embodiment, the power electronic converters are connected between the segregation means and the electrical propulsion systems.

The architecture according to the invention may comprise second means for segregating the electrical propulsion systems arranged on the electrical energy supply network and configured to impose a direction of flow of electric power from the second sources to the electrical propulsion systems. The second segregation means may comprise diodes.

According to one embodiment, the power electronic converters are connected between the second sources and the electrical propulsion systems, in parallel to the second segregation means.

Preferably, the first and second sources are segregated from each other. In other words, there is no communication between the different energy sources. More specifically, the first source may be segregated from each second source and each second source may be segregated from the first source and the other second sources.

According to one embodiment, the first source comprises a variable frequency generator (VFG). In this case, the architecture further comprises a passive rectifier connected to the first source. The rectifier may be an AC-DC (Alternative Current-Direct Current) converter.

According to one embodiment, the first source is a battery and the second sources are permanent magnet generators (PMGs).

A battery is an electrochemical source. For example, the first source can be a lithium-ion battery.

A permanent magnet machine is an electromechanical source.

The invention also relates to a multi-rotor aircraft, in particular with vertical take-off and landing, characterised in that it comprises a hybrid propulsion architecture according to the invention.

According to one embodiment, the aircraft is a dual-rotor counter-rotating quadricopter VTOL.

Advantageously, the aircraft according to the invention is tolerant to a single failure. More specifically, no malfunction results in the loss of more than one pair of rotors, i.e. two diametrically opposed rotors.

The elements having the same functions in the different implementations have the same references in the figures.

DESCRIPTION OF THE EMBODIMENTS

FIGS.4to8show a hybrid propulsion architecture100according to the invention, for a VTOL aircraft, such as a dual-rotor counter-rotating quadricopter.

The architecture100comprises a single first source102of a first type of energy. For example, as shown inFIGS.5to8, the first source102comprises a gas turbine110and a variable frequency generator112, followed by a passive rectifier114. The rectifier114is an AC-DC converter.

The first source102may also be a battery, for example a lithium-ion battery. Thus, the first source102may be an electrical-thermal generation source, or an electrochemical storage source.

The architecture100comprises second sources104of a second type of energy, which is different from the first type of energy of the first source102. InFIG.4, three second sources104are shown, and inFIGS.5to8, four second sources104are shown.

For example, the second sources104may comprise permanent magnet generators. As shown inFIGS.5to8, the second sources104may also be batteries. Thus, the second sources104may be electric-magnetic generation sources, or electrochemical storage sources.

Preferably, the first and second sources102,104are segregated from each other. In other words, there is no communication between the different energy sources. For example, the first source102is segregated from each second source104, and each second source104is segregated from the other second sources104and the first source102.

The architecture100comprises electrical propulsion systems106. InFIG.4, three electrical propulsion systems106are shown, and inFIGS.5to8, four electrical propulsion systems106are shown. The electrical propulsion system106may include a DC-AC converter (not shown), electric motors116connected to said DC-AC converter such that in operation the DC-AC converter supplies AC power to the electric motors116, and propellers (not shown) coupled to the electric motors116such that in operation the electric motors116drive the propellers.

The architecture100comprises an electrical energy supply network118that connects the first source102and the second sources104to the electrical propulsion systems106. The electrical energy supply network118may be an HVDC network.

In particular, each electrical propulsion system106is powered, via the electrical energy supply network118, by the first source102and by one of the second sources104.

The architecture100comprises propulsion channels108. InFIG.4, three propulsion channels108are shown, and inFIGS.5to8, four propulsion channels108are shown. Each propulsion channel108comprises the first source102, a second source104, an electrical propulsion system106, and a portion of the electrical energy supply network118that connects the first source, the second source104and the electrical propulsion system106together.

The architecture100also comprises means for segregating120the electrical propulsion systems106. The segregation means120are arranged on the electrical energy supply network118and are configured to impose a direction of flow of electric power from the first source102to the electrical propulsion systems106. The segregation means120ensure the segregation of the propulsion channels108.

The segregation means120enable the flux of electrical energy to be unidirectional from the first source102to the electrical propulsion systems106. The electrical energy is forced to flow from the common point P to the electrical propulsion systems106, but cannot flow from the electrical propulsion systems106to the common point P. Each propulsion channel108comprises segregation means120between the first source102and the electrical propulsion system106.

The segregation means120may comprise diodes, as shown inFIGS.5to8.

The architecture100may comprise power electronic converters connected to the electrical energy supply network118to improve the control of electrical energy in the various propulsion channels108.

According to an embodiment shown inFIG.6, power electronic converters122may be connected between each second source104and each electrical propulsion system106. The converters122may be DC-DC converters.

According to an embodiment shown inFIG.7, power electronic converters124may be connected on each propulsion channel118between the segregation means120and the electrical propulsion system106. The converters124may be DC-DC converters.

According to an embodiment shown inFIG.8, the architecture100may comprise second segregation means126of the electrical propulsion systems106. The segregation means126are arranged on the electrical energy supply network118and are configured to impose a direction of flow of electric power from the second sources104to the electrical propulsion systems106. The segregation means126enable the flux of electrical energy to be unidirectional from the second source104to the electrical propulsion systems106. Power electronic converters128may be connected on each propulsion channel118between the second source104and the electrical propulsion system106, in parallel to the segregation means126. The converters128may be DC-DC converters.

The hybrid propulsion architecture according to the invention has been mainly described for a dual-rotor counter-rotating quadricopter VTOL, but can of course be integrated in any kind of aircraft.