Device for powering an electrical network of an aeronautical propulsion system and associated method

Abstract

The present disclosure proposes a device (110) for powering an electrical network (120) of an aeronautical propulsion system (100), the device (110) comprising: an electrical generator (112), preferably a permanent-magnet synchronous electrical machine, comprising a rotor and a stator, the rotor being configured to be driven by a turbine engine (111), the stator being configured to generate a first AC voltage (V1); an AC / DC converter (114) configured to rectify the first voltage (V1) delivered by the electrical generator (112) so as to obtain a second voltage (V2); and a DC / DC converter (116) configured to chop the second voltage (V2) delivered by the AC / DC converter (114) so as to obtain a third voltage (V3), the DC / DC converter (116) being downstream of the AC / DC converter (114) with reference to current flow from the AC / DC converter (114) to the DC / DC converter (116).

Description

[0001] DESCRIPTION

[0002] TITLE: Device for supplying an electrical network of an aeronautical propulsion system and associated method

[0003] TECHNICAL FIELD

[0004] This presentation concerns the aeronautical field. More specifically, it concerns the power supply devices for the electrical networks of hybrid aeronautical propulsion systems, in particular their control, when they comprise an electric generator comprising a rotor and a stator, typically a synchronous electric machine with permanent magnets.

[0005] STATE OF THE ART

[0006] Some power supply devices for a propulsion system electrical network, particularly a turboprop, include two electrical machines, particularly of the permanent magnet synchronous type. One of the electrical machines is connected to the high-pressure shaft while the other electrical machine is connected to the low-pressure shaft of the turboprop. The two shafts can then transfer their mechanical (propulsive) power via the electrical machines according to the needs of the turboprop. The electrical machines also perform electrical (non-propulsive) power generation functions for the needs of the electrical network. Therefore, the power supply device includes a static AC / DC converter configured to rectify the current and voltage generated by each of the machines and intended to supply the electrical network.The turboprop is then qualified as being "hybrid" by combining the turboprop with the power supply device. Reference can be made to document FR 3 103 647 for more details on this subject.

[0007] Unlike wound synchronous machines, permanent magnet synchronous machines are lighter and less bulky. They also have better efficiency and better voltage quality. However, in a "constant power" operating mode of the electric machine, i.e. an operating mode in which the torque delivered by a rotor of the machine is inversely proportional to the turboprop engine speed (for example, a low-pressure shaft speed) to deliver constant power, the current delivered by the permanent magnet synchronous machine is proportional to the torque and the machine voltage is proportional to the speed. At low speed, this will result in high current operation (high torque) and at high speed, high voltage operation.

[0008] Therefore, due to a high speed range of the low pressure shaft compared to the high pressure shaft (a ratio between a minimum and maximum speed of the low pressure shaft is greater than 5 while such a ratio for the high pressure shaft does not exceed 2.5), the electrical machine connected to the low pressure shaft may generate high voltages or high currents requiring oversizing of the power supply device, including electrical machines, AC / DC converters and harnesses of the device, or even the electrical network.

[0009] GENERAL STATEMENT

[0010] One aim of this presentation is therefore to be able to power the electrical network of an aircraft, in particular a turboprop, over a high speed range. Secondarily, one aim of this presentation is to improve the power supply of the electrical networks of hybrid propulsion systems, in particular hybrid turboprops.

[0011] To this end, the present disclosure provides, according to a first aspect, a device for supplying an electrical network of an aeronautical propulsion system, the device comprising: an electrical generator, preferably a permanent magnet synchronous electrical machine, comprising a rotor and a stator, the rotor being configured to be driven by a turbomachine, the stator being configured to generate a first alternating voltage; an AC / DC converter configured to rectify the first voltage from the electrical generator into a second voltage; and a DC / DC converter configured to chop the second voltage from the AC / DC converter into a third voltage, the DC / DC converter being downstream of the AC / DC converter with reference to a current flow from the AC / DC converter to the DC / DC converter.

[0012] Some preferred but non-limiting features of the device according to the first aspect are the following, taken individually or in combination: the DC / DC converter is further configured to chop the second voltage when the second voltage is greater than the third voltage.; the device further comprises a control unit of the AC / DC converter and the DC / DC converter, the control unit being configured to determine a rotational speed of the rotor relative to the stator, the AC / DC converter being configured to rectify the first voltage as a function of the rotational speed of the rotor relative to the stator and the DC / DC converter being configured to chop the second voltage as a function of the rotational speed of the rotor relative to the stator;the control unit is further configured to compare the determined rotation speed with a first threshold value and a second threshold value, when the determined rotation speed is between the first threshold value and the second threshold value, the AC / DC converter being further configured to deflux the electrical generator as a function of the determined rotation speed so as to rectify the first voltage to the second voltage; the AC / DC converter is further configured to reduce the defluxing of the electrical generator by the AC / DC converter to a zero value when the determined rotation speed reaches the second threshold value; the third voltage is a voltage of the electrical network of the aeronautical propulsion system, for example between 535 V and 545 V, the second voltage being higher than the third voltage;the device further comprises: a second AC / DC converter, the AC / DC converters being interlaced; and two sets of capacitors mutually connected at the output of the AC / DC converters.;

[0013] According to a second aspect, there is provided an aeronautical propulsion system comprising an electrical network and a device according to the first aspect, the device being electrically connected to the electrical network.

[0014] According to a third aspect, there is provided an aircraft comprising an airframe and a propulsion system according to the second aspect, the propulsion system being attached to the airframe.

[0015] According to a fourth aspect, a method for supplying power to an electrical network of an aeronautical propulsion system is proposed, comprising the following steps: generating a first voltage; rectifying, by an AC / DC converter, the first voltage into a second voltage; then chopping, by a DC / DC converter separate from the AC / DC converter, the second voltage into a third voltage.

[0016] The method may further comprise a step of determining a rotational speed of a rotor of an electric generator relative to a stator of the electric generator, in which the rectification and chopping steps are implemented as a function of the determined rotational speed.

[0017] Optionally, the method further comprises the following steps: comparing the determined rotation speed with a first threshold value and a second threshold value; and if the determined rotation speed is between the first threshold value and the second threshold value, defluxing the electrical generator according to the determined rotation speed.

[0018] DESCRIPTION OF FIGURES

[0019] Other characteristics, aims and advantages will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which: Figure 1 is a schematic half-sectional view of a hybrid propulsion system; Figure 2 schematically illustrates a power supply device; Figure 3 illustrates a part of a power supply device; Figures 4a and 4b illustrate a part of an AC / DC converter; Figure 5 illustrates a part of a DC / DC converter; Figure 6 is a flowchart of a power supply method; Figure 7 illustrates a graph representing a change in an effective value of an electromotive force of the electric generator, a voltage of the electrical network and an output power of the electric generator as a function of a speed ratio of the low pressure shaft;Figure 8 illustrates a graph representing an evolution of an effective value of a phase current of the electric generator and of an output voltage of the AC / DC converter as a function of a speed ratio of the low pressure shaft; and Figure 9 illustrates a graph representing an evolution of a current of the electric generator of axis “d” of a Park frame and of an electric generator current of axis “q” of the Park frame as a function of a speed ratio of the low pressure shaft.;

[0020] DETAILED DESCRIPTION

[0021] A propulsion system 100 comprises a turbomachine 111 which has a main gas flow direction and which extends along a longitudinal axis X. The turbomachine 111 is configured to be fixed to an airframe of an aircraft, for example to the wings, in the case of an airplane, typically via a pylon (or mast). The turbomachine 111 may also be mounted at the rear of the fuselage, or even be integrated into the fuselage of the aircraft. The turbomachine 111 may be twin-spool, twin-flow, ducted and direct-drive, as described below, but may also comprise a different number of spools and / or flows, and / or be another type of turbojet, such as a geared turbojet or a turboprop, ducted or not.The turbomachine 111 comprises, from upstream to downstream in the direction of gas flow, a fan 1112, a primary body comprising a compression section 1113, 1114 comprising a low-pressure compressor 1113 and a high-pressure compressor 1114, a combustion chamber 1115, and a turbine section 1116, 1117 comprising a high-pressure turbine 1116 and a low-pressure turbine 1117. The fan 1112 may be shrouded, that is to say it is housed in a retention casing 1111 (figure 1). The fan may also be unducted, that is to say it is not housed in a retention casing and is in the form of a propeller 1110. The air flow entering the turbomachine 111 following the suction generated by the fan 1112 is divided into a primary flow configured to pass through the primary body and a secondary flow which bypasses the primary body, most of the thrust generated by the turbomachine 111 being linked to the secondary flow.Furthermore, the turbomachine 111 comprises a high pressure shaft 1118 which is connected to the high pressure turbine 1116 and is configured to drive the high pressure compressor 1114, and a low pressure shaft 1119 which is connected to the low pressure turbine 1117 and is configured to drive the low pressure compressor 1113 and the fan 1112. A rotational speed of the low pressure shaft 1119 may be between 1800 revolutions per minute and 10000 revolutions per minute. That is to say that a rotational speed ratio of the low pressure shaft 1119 may be greater than 5 while a rotational speed ratio of the high pressure shaft 1118 is generally between 1.5 and 2.5. Of course, the propulsion system 100 may comprise a plurality of turbomachines 111, for example one turbomachine 111 per wing of the aircraft.

[0022] The propulsion system 100 further comprises an electrical network 120 configured to transport electrical power within the propulsion system 100. The electrical network 120 may be of the high voltage direct current type (known by the English acronym HVDC for “High voltage direct current”). An operating voltage of the direct current electrical network 120 may for example be 540 V. In this regard, the electrical network 120 is configured to operate at constant voltage (the operating voltage of the electrical network 120).

[0023] The propulsion system 110 also comprises a power supply device 110 (illustrated for example in FIG. 1) connected to the electrical network 120. The propulsion system 110 may comprise several power supply devices connected in parallel to the electrical network 120. The power supply device comprises an electrical machine 112. In the case of a twin-spool turbomachine, the electrical machine 112 is configured to be connected to the low-pressure shaft 1119 or to the high-pressure shaft 1118. The propulsion system 100 may further comprise two power supply devices 110, each comprising an electrical machine 112 connected to one of the low-pressure shafts 1119 and high-pressure shafts 1118. In general, the propulsion system 110 may comprise several electrical power supply devices, each comprising an electrical machine 112 connected to a separate shaft of the turbomachine 111.The electrical machine 112 is an electromechanical converter, preferably of the synchronous type, for example with permanent magnets. The use of a permanent magnet synchronous electrical machine has the advantage of reducing the mass of the aircraft because it benefits from a high power density compared to other types of synchronous machines, for example wound rotor synchronous machines. The electrical machine 112 comprises a stator and a rotor that can rotate relative to the stator. The turbomachine 111 is connected to the rotor to be driven in rotation relative to the stator. For example, the rotor is connected either to the high pressure shaft 1118 or to the low pressure shaft 1119 of the turbomachine 111.The electrical machine 112 is reversible, that is to say that it is configured to operate as an electric generator for any rotation speed of the turbomachine 111, typically when it is connected to the low pressure shaft, and / or as an electric motor, typically when it is connected to the high pressure shaft. In this case, the power supply device 110 makes it possible to power the electrical network 120 by taking power from each shaft, typically the low pressure and high pressure shafts, when the two electrical machines are in generator mode, and to implement a power transfer, typically from the low pressure shaft to the high pressure shaft, when one of them is in electric motor mode.

[0024] In the following, the power supply device 110 will be described in an operating mode in which the power supply device 110 supplies the electrical network 120. Therefore, the electrical machine 112 will be described in an operating mode as an electric generator and will therefore be called an “electric generator”. Of course, what is described in the remainder of this presentation remains compatible with an operating mode of the power supply device 110 in “power transfer” in which the electrical machine 112 can be in an operating mode as an electric motor, in particular for the electrical machine connected to the high-pressure shaft.

[0025] The power supply device further comprises an AC / DC converter 114 electrically connected to the electrical generator 112, the AC / DC converter 114 being configured to rectify an AC electrical quantity into a DC electrical quantity. With reference to a current flow from the electrical generator 112, the AC / DC converter 114 is downstream of the electrical generator 112. The AC / DC converter 114 is configured to rectify a first voltage V1 from the electrical generator 112 into a second voltage V2. The AC / DC converter 114 operates as an active rectifier, that is to say that all the bridge arms 1141 of the AC / DC converter 114 comprise at least one active component, for example a transistor, the transistor possibly being of the MOSFET type.The AC / DC converter 114 may be a Vienna rectifier (known by the Anglo-Saxon name "Vienna"), of which an electrical diagram of a bridge arm 1141 of the Vienna rectifier is illustrated in FIG. 4a, an actively neutral clamped rectifier (known by the acronym ANPC for "Active neutral clamped point"), of which an electrical diagram of a bridge arm 1142 of the actively neutral clamped rectifier is illustrated in FIG. 4b, or a neutral clamped rectifier (known by the acronym NPC for "Neutral clamped point"). The Vienna rectifier has the advantage of improving the reliability of the AC / DC converter 114 and the ANPC and NPC rectifiers have the advantage of limiting Joule effect losses in the AC / DC converter 114. These architectures are in themselves known to a person skilled in the art and will therefore not be detailed further.

[0026] The power supply device 110 further comprises a DC / DC converter 116. The DC / DC converter 116 is electrically connected, on the one hand, to the electrical network 120 and, on the other hand, to the AC / DC converter 114 by a common capacitive intermediate bus 115. The intermediate bus 115 is configured to operate at an intermediate voltage (for example the second voltage V2) greater than or equal to the voltage V3, typically the operating voltage of the electrical network 120. With reference to a current flow from the AC / DC converter 114 to the DC / DC converter 116, the DC / DC converter 116 is downstream of the AC / DC converter 114. The DC / DC converter 116 is configured to chop the second voltage V2 from the AC / DC converter 114 into a third voltage V3, typically to lower the DC voltage of the intermediate bus 115 to supply the electrical network 120.Several examples of DC / DC converter architecture are described in patent FR 2 969 861 B1. The DC / DC converter can also be produced by interleaving several bridge arms 1161. An example of a bridge arm 1161 capable of being interleaved is notably illustrated in Figure 5. The implementation of a DC / DC converter 116 is part of the general knowledge of the person skilled in the art and will therefore not be detailed further.The power supply device 110 may further comprise a third filter 117 in series with the DC / DC converter 116 and downstream of the DC / DC converter 116 so as to be interposed between the electrical network 120 and the DC / DC converter. Thus, a combination of the AC / DC converters 114 and DC / DC converters 116 makes it possible to supply the electrical network 120 at constant power over a wide speed range, typically a speed range of the low pressure shaft 1119 or more generally a speed range in which the ratio between a minimum speed and a maximum speed of the speed range is greater than 5, without oversizing the generator, the cables and the converters themselves. The combination of the AC / DC converters 114 and DC / DC converters 116 also makes it possible to limit the risks of overvoltage on the electrical network 120.

[0027] Indeed, without the second modulation implemented by the DC / DC converter 116, the power supply device 110 can supply the electrical network 120 at constant power and at the voltage of the electrical network 120 in a reduced speed range of the turbomachine, typically up to 2.5 times a minimum rotation speed of the high pressure shaft 1118, instead of reaching a speed range going beyond 5 times the minimum rotation speed of the low pressure shaft 1119. A difficulty comes from the fact that, when the electrical machine 112 is in electrical generator mode, typically the electrical machine 112 connected to the low pressure shaft which operates with a speed ratio greater than 5, the first voltage V1 is linked to a rotation speed of the rotor of the electrical machine 112 relative to the stator of the electrical machine 112.Therefore, at high speed, the voltage will also be high, but at low speed, a current delivered by the electric generator 112 will be high to operate at constant power. The fact of "defluxing" the electric generator 112, for example by controlling an inverter driving the electric generator 112, makes it possible to limit these constraints. On the one hand, at low speed, the effect of the defluxing makes it possible to reduce the current from the electric generator 112 controlled only by the AC / DC converter 114, without the DC / DC converter 116, directly regulating a voltage from the electric generator 112 to a network voltage of 540V. For example, for an electric generator 112 of 150 kW, a current value is 750 A in effective value for a strong defluxing against 1100 A in effective value for a weak defluxing.On the other hand, at high speed, the effect of defluxing makes it possible to reduce the voltage V1 of the electric generator 112, under the same conditions of control by the AC / DC converter 114, by controlling a component of axis “d” of a Park reference of a current coming from the electric generator 112 (called a current Id). However, defluxing has at least one of the following limitations:.

[0028] - the current Id can become greater than a “q” axis component of the Park reference frame (called a current Iq) which can make a control of the third voltage V3, typically the voltage of the electrical network 120, unstable in the event of an error in a measurement or an estimation of a position of the rotor relative to the stator, however, this is a frequent risk for this type of application in view of an order of magnitude of the current Id which can be up to 6 times greater than the current Iq measured at nominal power of the electrical generator 112; and

[0029] - in the event of a fault or loss of control of the electrical generator 112, the first voltage V1 is no longer limited by the defluxing, thus generating overvoltages in the power supply device 110 and the electrical network 120.

[0030] Thus, defluxing can be used without risk of instability or damage to the power supply device 110 and the electrical network 120 only over a limited speed range. However, the ability of the DC / DC converter 116 to lower high voltages depends only on its sizing and therefore does not present any risks of instability or loss of control compared to defluxing. In addition, the DC / DC converter 16 makes it possible to avoid oversizing the power supply device 110, thus reducing the mass of the propulsion system 100. The DC / DC converter 116 also further reduces the constraints linked to low-speed currents. Indeed, an open-circuit voltage of the electrical generator 112, more commonly called electromotive force (or EMF), is higher and therefore reduces the current delivered by the electrical generator 112.For example, for a 150 kW generator, the maximum current at low speed is limited to 450 A in effective value compared to 750 A in effective value without DC / DC converter 116. Thus, the power supply device 110 can be used in a speed range of the turbomachine up to five times a minimum speed of the low pressure shaft 1119, preferably between five times and ten times the minimum speed of the low pressure shaft 1119, therefore over a much wider speed range compared to a power supply device without DC / DC converter. In addition, in the event of a short circuit on the electrical network 120, the DC / DC converter 116 makes it possible to limit a short-circuit current from the electrical network 120 so as not to damage the electrical generator 112 or the AC / DC converter 114 and limits the stresses on equipment of the electrical network 120, in particular cables and associated protections.Overall, the DC / DC converter 116 makes it possible to reduce the size of the power supply device 110 and therefore the mass of the propulsion system 100.

[0031] The power supply device 110 may further comprise a first filter 113 upstream of the AC / DC converter 114. The intermediate bus 115 comprises capacitors 119. Each capacitor 119 of the intermediate bus 115 is connected, on the one hand, to one of the two terminals of the power supply device 110 DC+, DC- and, on the other hand, to a midpoint M of the power supply device 110. Examples of electrical arrangement of the capacitors 119 are illustrated by way of example in FIG. 2 and FIG. 3. Thus, it is possible to share the capacitors for the AC / DC converters 114 and DC / DC 116 without oversizing them given that the AC / DC converters 114 and DC / DC 116 are not intended to switch at the same time in the device 110.The power supply device 110 may have different architectures, for example an architecture in which the electrical generator 112 and the AC / DC converter 114 are in series, an example of which is illustrated in FIG. 2, or an interleaving architecture, an example of which is illustrated in FIG. 3. In the case of the interleaving architecture, two AC / DC converters 114 are connected on the DC side in parallel. The interleaving consists of phase-shifting the control commands of the two AC / DC converters 114 by 180° in order to reduce current oscillations in the capacitors. To do this, the electrical machine 112 comprises two independent three-phase stators. According to the example illustrated in FIG. 3, the electrical machine 112 is illustrated equivalently by two electrical machines in which their rotors are mutually connected to the same shaft, typically the low-pressure shaft.The interlacing architecture also has the advantage of limiting a dimension of the cables of the power supply device 110, thus facilitating their connections within the propulsion system 100. It also has the advantage of reducing a value of the current in the capacitors 119 of the intermediate DC bus 115 by pooling the capacitors 119 connected to each of the interlaced AC / DC rectifiers 114.

[0032] The power supply device 110 may further comprise a control unit 118 configured to determine a rotational speed of the rotor of the electric generator 112 relative to the stator of the electric generator and to control a rectification implemented by the AC / DC converter 114 as well as a chopping implemented by the DC / DC converter 116, using voltage and current loops, as a function of the determined rotational speed. Indeed, for a speed lower than a first threshold value S1, corresponding for example to a low speed of the low pressure shaft 1119, a voltage generated by the electric generator V1 is lower than a supply voltage V3 (see the electromotive force Vf emwith respect to the supply voltage V3 in figure 7), typically a supply voltage of the electrical network 120. The AC / DC converter 114 operates in voltage boost mode and regulates the generated voltage V1 into an intermediate voltage V2 equal to the supply voltage of the electrical network V3 (see the intermediate voltage V2 in figure 8 which remains constant while the generated voltage V1 continues to increase according to the evolution of the electromotive force Vf emin figure 7). As for the DC / DC converter 116, it operates in continuous conduction and directly transmits the intermediate voltage V2, coming from the intermediate bus 115, without modifying it. That is to say that the transmitted intermediate voltage V2 remains equal to the voltage of the electrical network V3. For a speed greater than a second threshold value S2, corresponding for example to a high speed of the low pressure shaft 1119, the voltage generated by the electrical generator V1 is greater than the supply voltage V3 (figure 7). Thus, the AC / DC converter 114 operates in “diode bridge rectifier” mode and no longer switches. From then on, the intermediate voltage V2 increases (see the intermediate voltage V2 in figure 8 which increases at the same time as the generated voltage V1 continues to increase according to the evolution of the electromotive force Vf emin Figure 7). The DC / DC converter 116 then operates in voltage step-down mode and reduces the intermediate voltage V2, which increases since it is no longer regulated by the AC / DC converter 114, to a voltage equal to the supply voltage V3. Thus, the control unit 118 has two operating modes. A first mode (boost), in which the control unit 118 controls the AC / DC converter 114 in active rectifier mode and the DC / DC converter 116 in continuous conduction mode. The AC / DC converter 114 therefore regulates the voltage generated by the electrical generator V1 to the supply voltage V3, typically from the 540V electrical network. A second mode, in which the control unit 118 controls the AC / DC converter 114 in “diode bridge rectifier” mode and the DC / DC converter 116 in voltage step-down mode. The DC / DC converter 116 therefore regulates the supply voltage V3, typically from the electrical network to 540V.Therefore, advantageously, the AC / DC converters 114 and DC / DC converters 116 do not switch at the same time. The switching losses of the power supply device 118 are therefore reduced. Indeed, in the first operating mode, the intermediate voltage V2 is reduced, which makes it possible to reduce the switching losses at the AC / DC converter 114 and the DC / DC converter 116 does not switch, so there are no switching losses at the DC / DC converter 116. In the second operating mode, the DC / DC converter 116 switches but not the AC / DC converter 114. In this case, there are no switching losses at the AC / DC converter 114.Furthermore, since the AC / DC converter 114 only switches in the presence of a reduced intermediate voltage V2, typically 540V, the overvoltages at the level of the cables connecting the electric generator 112 and the AC / DC converter are also reduced in order to be below a voltage of the electric generator 112 in operation at full speed, thus limiting the sizing of the insulations of the cables of the power supply device 110 and of the electric generator 112 as well as of the first filter 113 and therefore reduces the mass of the propulsion system 100. Furthermore, the AC / DC converter 114 and the DC / DC converter 116 are controlled independently. Consequently, control of the converters is simplified. Furthermore, the change of control mode takes place without any impact on the operating voltage of the electrical network 120.In addition, a current cut at the output of the AC / DC converter 114, in this case cut at the output of the AC / DC converter 114, and an input current of the DC / DC converter 116 do not accumulate in the capacitors 119 of the second filter 115, thus reducing its dimensioning. To determine the rotation speed, the power supply device 110 may comprise a speed or position sensor configured to measure the rotation speed. The rotation speed may also be determined by an estimation, for example from currents or voltages of the electric generator 112. The sensor and the estimation previously described are part of the general knowledge of the person skilled in the art and will not be detailed further in this presentation.

[0033] In order to further reduce the dimensioning of the power supply circuit 120 and further reduce the mass of the propulsion system 100, the control unit 118 can control the AC / DC converter 114 to deflux the electric generator 112 if the determined rotation speed is between the first threshold value S1 and the second threshold value S2. Indeed, between the first and second threshold values ​​S1, S2, the intermediate voltage V2 may still prove to be too low in operation of the AC / DC converter in “diode bridge rectifier” mode because the generated voltage V1 may still be below the supply voltage V3 (see FIG. 7). This is also the case in active rectifier mode. Indeed, the generated voltage V1 is in the vicinity of the supply voltage V3.Therefore, the control unit 110 controls the AC / DC converter 114 so that the AC / DC converter 114 defluxes the electric generator 114 by injecting a current Id, which implies a slight increase in a phase current 11 (see the current Id and phase 11 increasing between the threshold values ​​S1, S2 in Figure 9) to continue to maintain the intermediate voltage V2 at the supply voltage V3, for example the supply voltage of the network at 540 V. Such a control also has the advantage of guaranteeing stable control of the first voltage V1. Indeed, at any operating point in which the speed is between the first threshold value S1 and the second threshold value S2, a value of the current Id does not exceed a value of the current Iq (see for example the currents Id, Iq between the threshold values ​​S1, S2 in Figure 9).Furthermore, the control unit is configured to control the AC / DC converter 114 to implement a reduction in the defluxing to a zero value when the rotation speed reaches the second threshold value S2. Thus, the reduction in the defluxing causes the AC / DC converter 114 to switch to “diode bridge” mode (the intermediate voltage V2 in FIG. 8 increases again during the reduction in the current Id in FIG. 9) and the DC / DC converter 116 to switch to voltage step-down mode. Thus, the change in operating mode takes place without any impact on the electrical network 120 and the converters 114, 116. Furthermore, since the reduction in the defluxing involves a transient period during which the AC / DC converters 114 (defluxing) and DC / DC converters 116 (voltage step-down) are in operation, the control by the control unit makes it possible to reduce this period to a few milliseconds, preferably 10 milliseconds.Thus, stresses on the capacitors 119 and thermal heating of the power supply device 110 are reduced.

[0034] Thus, in order to operate over a wide speed range of the turbomachine 111, the power supply circuit 120 of the electrical network 110 is configured to implement a method of powering the electrical network 120 in which, with reference to FIG. 6, the following steps are implemented.

[0035] During a step E1, the first voltage V1 is generated by the electric generator 112.

[0036] During a step E11, it may be provided that the control unit 118 determines a speed of the rotor of the electric generator 112 relative to the stator of the electric generator 112.

[0037] Furthermore, during a step E2, the control unit 118 compares the rotation speed determined in step E11 with the first threshold value S1 and the second threshold value S2 so that the control unit 118 selects an operating mode for each of the AC / DC converters 114 and DC / DC converters 116.

[0038] During a step E3, the AC / DC converter 114 rectifies the first voltage V1 into the second voltage V2. Typically, if the determined rotation speed is lower than the first threshold value S1, then the rectification is implemented by the AC / DC converter 114 in active rectifier mode. If the determined rotation speed is higher than the second threshold value S2, then the rectification is implemented by the AC / DC converter 114 in “diode bridge rectifier” mode. Therefore, step E3 can be implemented as a function of the determined rotation speed.

[0039] During a step E4, the DC / DC converter 116 chops the second voltage V2 into the third voltage V3. Typically, if the determined speed is lower than the first threshold value S1, the chopping is implemented by the DC / DC converter 116 in continuous conduction mode. If the determined speed is higher than the second threshold value S2, then the chopping is implemented by the DC / DC converter 116 in voltage step-down mode. Therefore, step E4 can be implemented according to the determined rotation speed.

[0040] A step E5 may also be provided, in which, if the determined rotation speed is between the first threshold value S1 and the second threshold value S2, the AC / DC converter 114 defluxes the electrical generator 112 as a function of the rotation speed determined in step E11. In this case, during defluxing, the rectification is implemented by the AC / DC converter 114 in active rectifier mode and the chopping is implemented by the DC / DC converter 116 in continuous conduction mode.

Claims

CLAIMS 1. A power supply device (110) for an electrical network (120) of an aeronautical propulsion system (100), the device (110) comprising: an electrical generator (112), preferably a permanent magnet synchronous electrical machine, comprising a rotor and a stator, the rotor being configured to be driven by a turbomachine (111), the stator being configured to generate a first alternating voltage (V1); an AC / DC converter (114) configured to rectify the first voltage (V1) from the electrical generator (112) into a second voltage (V2); and a DC / DC converter (116) configured to chop the second voltage (V2) from the AC / DC converter (114) into a third voltage (V3), the DC / DC converter (116) being downstream of the AC / DC converter (114) with reference to a current flow from the AC / DC converter (114) to the DC / DC converter (116).

2. Device (110) according to claim 1, wherein the DC / DC converter is further configured to chop the second voltage (V2) when the second voltage (V2) is greater than the third voltage (V3).

3. Device (110) according to one of claims 1 and 2, further comprising a control unit (118) for the AC / DC converter (114) and the DC / DC converter (116), the control unit (118) being configured to determine a rotation speed of the rotor relative to the stator, the AC / DC converter being configured to rectify the first voltage as a function of the rotation speed of the rotor relative to the stator and the DC / DC converter being configured to chop the second voltage as a function of the rotation speed of the rotor relative to the stator.

4. Device (110) according to claim 3, wherein the control unit (118) is further configured to compare the determined rotation speed with a first threshold value (S1) and a second threshold value (S2), when the determined rotation speed is between the first threshold value (S1) and the second threshold value (S2), the AC / DC converter (114) being further configured to deflux the electric generator (114) as a function of the determined rotation speed so as to rectify the first voltage (V1) into the second voltage (V2).

5. Device (110) according to claim 4, wherein the AC / DC converter (114) is further configured to reduce the defluxing of the electric generator (112) by the AC / DC converter (114) to a zero value when the determined rotational speed reaches the second threshold value (S2).

6. Device (110) according to one of claims 1 to 5, in which the third voltage (V3) is a voltage of the electrical network of the aeronautical propulsion system (100), for example between 535 V and 545 V, the second voltage (V2) being higher than the third voltage (V3).

7. Device according to one of claims 1 to 6, further comprising: a second AC / DC converter (114), the AC / DC converters (114) being interlaced; and two sets of capacitors (119) mutually connected at the output of the AC / DC converters (114).

8. Aeronautical propulsion system (100) comprising an electrical network (120) and a device (110) according to one of claims 1 to 7, the device (110) being electrically connected to the electrical network (120).

9. Aircraft (1) comprising an airframe (10) and a propulsion system (100) according to claim 8, the propulsion system (100) being attached to the airframe (10).

10. Method for supplying an electrical network (120) of an aeronautical propulsion system (100), comprising the following steps: generating (E1) a first voltage (V1); rectifying (E3), by an AC / DC converter (114), the first voltage (V1) into a second voltage (V2); then chopping (E4), by a DC / DC converter (116) separate from the AC / DC converter (114), the second voltage (V2) into a third voltage (V3).

11. Method according to claim 10, further comprising a step of determining (E11) a rotational speed of a rotor of an electric generator (112) relative to a stator of the electric generator (112), in which the rectifying (E3) and chopping (E4) steps are implemented as a function of the determined rotational speed.

12. The method of claim 11, further comprising the following steps: comparing the determined rotational speed (E2) with a first threshold value (S1) and a second threshold value (S2); and if the determined rotation speed is between the first threshold value (S1) and the second threshold value (S2), defluxing (E5) the electric generator (112) according to the determined rotation speed.

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