Hybrid electrical architecture for an aircraft

Abstract

The invention relates to a hybrid electrical architecture (101) for an aircraft (103) which comprises a turbomachine (107) and a reduction gearbox (111) intended to rotate at least one propulsion member (105) of the aircraft (103). The architecture (101) also comprises at least one low-voltage electrical network (113) with at least one low-voltage electric machine (117, 118) mounted on the reduction gearbox (111) or on the turbomachine (107) and a high-voltage electrical network (125) with high-voltage electric machines (129) mounted on the turbomachine (107).

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: HYBRID ELECTRIC ARCHITECTURE OF AN AIRCRAFT

[0003] TECHNICAL FIELD

[0004] The invention relates to the field of aircraft with so-called hybrid propulsion, that is to say aircraft which combine two propulsion sources of different nature, for example a thermal source and an electrical source. It relates in particular to a hybrid electrical aircraft architecture.

[0005] PRIOR ART

[0006] Document FR-A1-2 962404 describes a hybrid electrical architecture in which an auxiliary electrical network is said to be disconnectable.

[0007] The architecture described in this document is a so-called parallel hybrid electrical architecture in which, on the one hand, two high-voltage electrical machines are mounted on the main gearbox and have a reversible operation, that is to say they are capable of both supplying torque to one or more rotors via the main gearbox or generating electrical energy from a torque draw from one or more shafts via the main gearbox. And, on the other hand, a so-called low-voltage electrical machine (i.e. which operates for example at 28 Volts) is driven by the high-pressure body of the aircraft turbomachine to operate as a generator (of electrical energy) or as a motor to start the turbomachine.

[0008] Although this architecture theoretically allows electrical power to be transferred between low-voltage and high-voltage electrical machines, it nevertheless has several drawbacks.

[0009] First, the low-voltage electrical machine can only operate in engine mode during turbomachine start-up. It cannot mechanically assist the high-pressure body of the turbomachine (by providing torque) continuously beyond 80% Nl. Indeed, the design of the electrical machine and the accessory gearbox (or AGB) means that it is not possible to provide engine torque to drive the high-pressure body beyond approximately 50 to 60% N1. This is due in particular to the current technology of electrical machines used as starter / generators and to the fact that such a need has not been identified until now.

[0010] Furthermore, low voltage operation quickly induces high electrical currents to be able to transfer significant powers (of the order of a few tens of kilowatts), which implies using large sections of electrical conductors and which leads to a high mass.

[0011] Furthermore, the transfer of electrical power from the low-voltage electrical machine to a high-voltage electrical machine is done via two different network voltages, which requires the use of a converter and therefore significantly reduces the efficiency of this power transfer. In addition, this creates a common point between the low-voltage and high-voltage networks, which increases the risk of propagation of faults between the two networks.

[0012] Finally, the mass penalty linked to the use of a high-voltage battery in the architecture can be prohibitive for aerial work missions.

[0013] SUMMARY OF THE INVENTION

[0014] The present invention provides a solution to these drawbacks.

[0015] In particular, the objectives of the invention are both to enable a transfer of power between the high-pressure body and the low-pressure body or the main gearbox of the aircraft, in both possible transfer directions, using a high-voltage network (also called an internal hybrid electrical network) only (i.e. without using the low-voltage network used to power the aircraft equipment) and to enable the internal hybrid electrical network (i.e. the propulsion electrical network) to be isolated from the electrical networks intended to power the aircraft equipment (i.e. the non-propulsion electrical network). In other words, it is a question of achieving a segregation of the non-propulsion and propulsion electrical networks. To this end, the invention according to a first aspect relates to a hybrid electrical architecture for an aircraft,said architecture comprising a turbomachine and a reducer intended to rotate at least one propulsion member of said aircraft, said architecture further comprising a low-voltage electrical network comprising a low-voltage electrical energy store and at least one low-voltage electrical machine electrically connected to a first electrical bus intended to supply electrical energy to loads of the aircraft, and a high-voltage electrical network comprising two high-voltage electrical machines electrically connected to a second electrical bus, said second electrical bus being electrically connected to the first electrical bus via an electrical converter of said high-voltage electrical network and a first contactor of said low-voltage electrical network, said architecture being characterized in that,the two high-voltage electrical machines are mounted on the turbomachine and each mechanically coupled to a shaft of said turbomachine, and, the at least one low-voltage electrical machine is mounted on the reducer or on the turbomachine and mechanically coupled to said reducer or to a shaft of said turbomachine.,

[0016] According to one embodiment, a first high-voltage electrical machine is mounted on a low-pressure body of the turbomachine and mechanically coupled to a shaft of said low-pressure body, a second high-voltage electrical machine is mounted on a high-pressure body of the turbomachine and mechanically coupled to a shaft of said high-pressure body, and a first low-voltage electrical machine is mechanically coupled to the reducer.

[0017] According to another embodiment, the high-voltage network further comprises a high-voltage electrical energy store connected to the second electrical bus, preferably via an electrical protection device. According to another embodiment, a first high-voltage electrical machine is mounted on a low-pressure body of the turbomachine and mechanically coupled to a shaft of said low-pressure body, a second high-voltage electrical machine is mounted on a high-pressure body of the turbomachine and mechanically coupled to a shaft of said high-pressure body, and a first low-voltage electrical machine is also mounted on the high-pressure body of the turbomachine and mechanically coupled to a shaft of said high-pressure body.According to another embodiment, the second high voltage electrical machine and the first low voltage electrical machine are separate windings of a double winding electrical machine, these separate windings being isolated from each other by galvanic isolation.

[0018] According to another embodiment, a second low-voltage electrical machine is mounted on the low-pressure body of the turbomachine and coupled to a shaft of said low-pressure body.

[0019] According to another embodiment, the first high voltage electrical machine and the second low voltage electrical machine are separate windings of a double winding electrical machine, these separate windings being isolated from each other by galvanic isolation.

[0020] According to another embodiment, the first low-voltage electrical machine and the second low-voltage electrical machine are respectively mechanically coupled to power take-offs of the high-pressure body of the turbomachine and the low-pressure body of the turbomachine, distinct from power take-offs of said high-pressure body and said low-pressure body to which the first high-voltage electrical machine and the second high-voltage electrical machine are coupled.

[0021] According to another embodiment, the high-voltage electrical machines are electrically connected to the second electrical bus via second contactors and the at least one low-voltage electrical machine is electrically connected to the first electrical bus via at least one third contactor. Furthermore, the invention according to a second aspect also relates to an aircraft comprising a turbomachine configured to rotate a propulsion member and a hybrid electrical architecture according to any one of the preceding claims.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which: Figure 1 is a schematic representation of an aircraft comprising a hybrid electric architecture according to a first embodiment of the invention; Figure 2 is a schematic representation of an aircraft comprising a hybrid electric architecture according to a second embodiment of the invention; Figure 3 is a schematic representation of an aircraft comprising a hybrid electric architecture according to a third embodiment of the invention; Figure 4 is a schematic representation of an aircraft comprising a hybrid electric architecture according to a fourth embodiment of the invention;and, Figure 5 is a schematic representation of an aircraft comprising a hybrid electric architecture according to a fifth embodiment of the invention.;

[0024] DESCRIPTION OF EMBODIMENTS

[0025] With reference to Figure 1, we will now describe a first embodiment of a hybrid electric architecture 101 of an aircraft 103 according to the invention.

[0026] In Figure 1 as in the following figures, the mechanical power, passing between the different elements of the architecture, is symbolized by three parallel lines while the electrical power is symbolized by a single line. In the non-limiting example shown, the aircraft 103 is a rotary wing aircraft, such as for example a helicopter. In this case, the rotary wing (not shown) is driven in rotation by a propulsion member 105 of the aircraft 103. More particularly, the architecture 101 comprises a turbomachine 107 mechanically coupled, by means of a freewheel 109 (in English "overrunning clutch"), to a reduction gear 111, in this case a main transmission box 111 intended to drive in rotation the propulsion member 105 (in this case a rotor mast called rotor in what follows) of the aircraft 103.Thus, in operation, the turbomachine 107 rotates the main gearbox 111 which in turn rotates the rotor 105.

[0027] Those skilled in the art will appreciate that the invention also applies to an aircraft using at least one propulsion unit of the electric hybrid turboprop type, having as its propulsion member a propulsive propeller and in which the reducer is a “Power Gear Box”.

[0028] In addition, the main gearbox 111 may also be configured to rotate other rotors not shown, for example an anti-torque rotor (also called a tail rotor).

[0029] The architecture 101 also comprises a low-voltage electrical network 113 which comprises a low-voltage electrical energy store 115, such as for example a battery, and at least one low-voltage electrical machine 117. Here, and in the following, the expression “low voltage” designates a voltage lower than 50 Volts, such as for example a voltage of 28 Volts. Those skilled in the art will further appreciate that, in this architecture, the low-voltage electrical machine 117 may be optional, in particular when it is used in a light helicopter and more particularly a non-IFR light helicopter (i.e. not intended for instrument flight). The low-voltage electrical machine 117 and the low-voltage electrical energy store 115 are electrically connected to an electrical bus 119 intended to supply electrical energy to loads 121 of the aircraft 103.

[0030] For example, the low voltage electrical machine 117 (which provides, for example, an electrical power of less than 9 Kilowatts) and the low voltage electrical energy store 115 deliver an electrical voltage of 28 Volts so that the low voltage electrical network has a nominal voltage equal to 28 Volts.

[0031] In the non-limiting example shown in Figure 1, the electrical bus 119 is split into two parts 119a and 119b which are connected to each other by a contactor 123 making it possible to electrically connect or disconnect the two parts 119a and 119b of the electrical bus 119 and consequently to segregate the part of the bus powered by the low voltage electrical network 113, that is to say the part 119a, and the part of the bus powered by a high voltage electrical network 125 described in more detail later.

[0032] Furthermore, in this configuration, the loads 121 can also be split into two groups of loads 121a and 121b capable of being powered by the part 119a and / or the part 119b of the electrical bus 119 so that an “emergency” power supply can be provided to each of the loads 121. The two groups of loads 121a and 121b can be, for example, respectively, equipment of the aircraft 103 whose operation is considered essential and equipment of the aircraft 103 whose operation is considered accessory.

[0033] In the non-limiting example described here, the low-voltage electrical network 113 further comprises a ground socket 127, which can be connected to a ground generator, i.e. a generator forming part of the ground infrastructure, to which the aircraft can be connected when it is parked to supply it with electrical energy and which provides electrical power (at a voltage of 28V).

[0034] As mentioned above, the architecture 101 also comprises a high-voltage electrical network 125 which comprises two high-voltage electrical machines 129 electrically connected to an electrical bus 131. The electrical bus 131 is electrically connected to the electrical bus 119 via an electrical converter 133 which is also included in the high-voltage electrical network 125. Here, and in what follows, the expression “high voltage” designates a voltage greater than 50 Volts. By way of non-limiting example, the voltage levels used may be 115 Volts in alternating voltage or 270 Volts, 540 Volts or even 800 Volts in direct voltage. Furthermore, there is no upper limit to the voltage value corresponding to “high voltage”.

[0035] The electrical converter 133 may be, for example, a DC / DC converter or an AC / DC converter whose role is, in all cases, to adapt the voltage of the high voltage electrical network 125 to the voltage of the low voltage electrical network 113.

[0036] Furthermore, the electrical converter 133 is connected to the electrical bus 119 of the low voltage electrical network 113 via a contactor 135 which is included in said low voltage electrical network 113.

[0037] The high-voltage electrical network 125 also comprises power and control electronics components 137, also designated by the acronym EPCU (Electrical Power Control Unit), electrically connected to the high-voltage electrical machines 129, and configured to regulate the voltage delivered by said high-voltage electrical machines 129 and to enable their control. In the example shown in FIG. 1, the two high-voltage electrical machines 129 are mounted on the turbomachine 107 and mechanically coupled to a shaft (not shown) of said turbomachine 107. The fact that the high-voltage electrical machines 129 are mounted on the turbomachine 107 means that there are at least two mechanical inputs on the turbomachine 107 for connecting the electrical machines 129 to both the high-pressure body and the low-pressure body.In addition, there are at least two rotary power take-offs connected to the rotor shaft of each electric machine 129, and each capable of transmitting the power supplied or taken by the electric machine and at least two fixing interfaces making it possible to secure the static casing of the electric machines 129 to the turbomachine 107.

[0038] Furthermore, the mechanical coupling in question implies that the electrical machines can receive or supply torque to the shaft of the turbomachine to which they are coupled depending on whether it operates as a generator or as a motor.

[0039] More precisely, in the configuration shown in FIG. 1, one of the two high-voltage electrical machines 129 is mounted on a low-pressure body 139 of the turbomachine 107 and therefore mechanically coupled to a shaft of this low-pressure body 139. While the other high-voltage electrical machine 129 is mounted on a high-pressure body 141 of the turbomachine 107 and therefore mechanically coupled to a shaft of this high-pressure body 141. As a result, this high-voltage electrical machine 129 mechanically coupled to a shaft of this high-pressure body 141 is capable of starting the turbomachine 107.

[0040] The two high-voltage electrical machines 129 are reversible, that is, they can drive the turbomachine 107 or draw mechanical power from said turbomachine 107 to generate electrical energy. Thus, mechanical power can pass from the high-pressure body 141 to the low-pressure body 139, and vice versa, via the high-voltage electrical machines 129. Furthermore, for such reversibility to be possible, the two EPCUs 137 are also designed to be reversible, since the electrical energy generated by one or other of the high-voltage electrical machines 129 must be able to pass through the ECPUs 137 via the electrical bus 131 which electrically connects them.

[0041] In addition, the low voltage electrical machine 117 is mechanically coupled to the main transmission box 111. In this configuration, the low voltage electrical machine 117 is, for its part, only used as a generator.

[0042] Finally, in addition to the contactors already mentioned above, the high-voltage electrical machines 129 are electrically connected to the electrical bus 131 via contactors 143 which, if necessary, allow them to be protected respectively in the event of an electrical fault on the electrical bus 131 or to prevent an electrical fault from propagating from one electrical machine 129 to another. Furthermore, the low-voltage electrical machine 117 is also electrically connected to the electrical bus 119 via a contactor 145.

[0043] Figure 2 represents another embodiment of the hybrid electrical architecture 101 in which, in addition to all the elements already described with reference to Figure 1, the high-voltage network 125 also comprises a high-voltage electrical energy store 147 connected to the electrical bus 131. Furthermore, in the non-limiting example shown, the high-voltage electrical energy store 147 is connected to the electrical bus 131 via an electrical protection device 149. This electrical protection device 149 is capable of electrically isolating the energy store in the event of an electrical fault on the network or of the store itself. It may be an electromechanical contactor, a static contactor or a mixed device such as a pyro-contactor or a pyro-fuse.

[0044] Advantageously, the high-voltage electrical energy store 147 makes it possible to stabilize the electrical bus 131 and / or to provide an additional hybridization source if necessary.

[0045] Figure 3 also shows another embodiment of the hybrid electric architecture 101 in which, this time, a high voltage electric machine 129 is mounted on the low pressure body 139 and mechanically coupled to a shaft of said low pressure body 139, another high voltage electric machine 129 is mounted on the high pressure body 141 and mechanically coupled to a shaft of said high pressure body 141, and the low voltage electric machine 118 is also mounted on the high pressure body 141 and mechanically coupled to a shaft of said high pressure body 141. In this case, the low voltage electric machine 118 can also be used as a starter of the high pressure body 141 of the turbomachine 107. Furthermore, those skilled in the art will appreciate that, in this configuration, the converter 133 is optional.

[0046] Furthermore, in the configuration shown in Figure 3, the high voltage electrical machine 129 and the low voltage electrical machine 118 which are mounted on the high pressure body 141 are in fact separate windings of a double winding electrical machine 151. These separate windings are isolated from each other by galvanic isolation to ensure segregation between the two networks.

[0047] Figure 4 shows yet another embodiment repeating the configuration of the embodiment of Figure 3 but adding a second low-voltage electrical machine 117 which is mounted on the low-pressure body 139 of the turbomachine 107 and coupled to a shaft of said low-pressure body 139. Furthermore, in this configuration, due to a sufficient number of low-voltage sources, the converter 133 and the contactor 135 are eliminated. Similarly, as in the case of the embodiment described with reference to Figure 3, the high-voltage electrical machine 129 and the low-voltage electrical machine 117 mounted on the low-pressure body 139 are in fact separate windings of a double-winding electrical machine 151. These separate windings are also isolated from each other by galvanic isolation.

[0048] Finally, Figure 5 represents a last embodiment in which the low voltage electrical network 113 comprises two low voltage electrical machines 118 and 117 which are respectively mechanically coupled to power take-offs of the high pressure body 141 of the turbomachine 107 and of the low pressure body 139 of the turbomachine 107. These power take-offs are distinct from the power take-offs of said high pressure body 141 and of said low pressure body 139 to which the two high voltage electrical machines 129 are respectively coupled. In addition, the low voltage electrical machine 118 mounted on the high pressure body 141 can be used as a generator or as a starter.

Claims

DEMANDS 1. Hybrid electrical aircraft architecture (101) of aircraft (103), said architecture (101) comprising a turbomachine (107) and a reduction gear (111) for driving in rotation at least one propulsion element (105) of said aircraft (103), said architecture (101) further comprising, a low-voltage electrical network (113) comprising a low-voltage electrical energy storage unit (115) and at least one low-voltage electrical machine (117, 118) electrically connected to a first electrical bus (119) for supplying electrical energy to loads (121) of the aircraft (103), and, a high-voltage electrical network (125) comprising two high-voltage electrical machines (129) electrically connected to a second electrical bus (131),said second electrical bus (131) being electrically connected to the first electrical bus (119) via an electrical converter (133) of said high-voltage electrical network (125) and a first contactor (135) of said low-voltage electrical network (113), said architecture (101) being characterized in that the two high-voltage electrical machines (129) are mounted on the turbomachine (107) and each mechanically coupled to a shaft (139, 141) of said turbomachine (107), and at least one low-voltage electrical machine (117, 118) is mounted on the gearbox (111) or on the turbomachine (107) and mechanically coupled to said gearbox (111) or to a shaft of said turbomachine (107).

2. Architecture (101) according to claim 1, wherein a first high-voltage electrical machine (129) is mounted on a low-pressure body (139) of the turbomachine (107) and mechanically coupled to a shaft of said low-pressure body (139), a second high-voltage electrical machine (129) is mounted on a high-pressure body (141) of the turbomachine (107) and mechanically coupled to a shaft of said high-pressure body (141), and a first low-voltage electrical machine (117) is mechanically coupled to the reducer (111).

3. Architecture (101) according to claim 2, wherein the high voltage network (125) further comprises a high voltage electrical energy storage unit (147) connected to the second electrical bus (131), preferably via an electrical protection device (149).

4. Architecture (101) according to claim 1, wherein a first high-voltage electric machine (129) is mounted on a low-pressure body (139) of the turbomachine (107) and mechanically coupled to a shaft of said low-pressure body (139), a second high-voltage electric machine (129) is mounted on a high-pressure body (141) of the turbomachine (107) and mechanically coupled to a shaft of said high-pressure body (141), and a first low-voltage electric machine (118) is also mounted on the high-pressure body (141) of the turbomachine (107) and mechanically coupled to a shaft of said high-pressure body (141).

5. Architecture (101) according to claim 4, wherein the second high-voltage electric machine (129) and the first low-voltage electric machine (118) are separate windings of a double-winding electric machine (151), these separate windings being insulated from each other by galvanic insulation.

6. Architecture (101) according to claim 4 or claim 5, wherein a second low-voltage electrical machine (117) is mounted on the low-pressure body (139) of the turbomachine (107) and coupled to a shaft of said low-pressure body (139). Architecture (101) according to claim 6, wherein the first high-voltage electric machine (129) and the second low-voltage electric machine (117) are separate windings of a double-winding electric machine (151), these separate windings being insulated from each other by galvanic insulation. Architecture (101) according to claim 6, wherein the first low-voltage electric machine (118) and the second low-voltage electric machine (117) are respectively mechanically coupled to power take-offs of the high-pressure body (141) of the turbomachine (107) and the low-pressure body (139) of the turbomachine (107), separate from power take-offs of said high-pressure body (141) and said low-pressure body (139) to which the first high-voltage electric machine (129) and the second high-voltage electric machine (129) are coupled.An architecture (101) according to any one of the preceding claims, wherein the high-voltage electrical machines (129) are electrically connected to the second electrical bus (131) via second contactors (143), and at least one low-voltage electrical machine (118) is electrically connected to the first electrical bus (119) via at least one third contactor (145). An aircraft (103) comprising a turbomachine (107) configured to drive a propulsion unit (105) and a hybrid electrical architecture (101) according to any one of the preceding claims.

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