Method for controlling an at least two-stage thermodynamic system of a motor vehicle

Abstract

The invention relates to a method for controlling a thermodynamic system having m supercharging stages, m>=2, including a supercharging stage n comprising a turbine (Tn), an electric machine (EMGn), a compressor (Cn) and a combustion chamber (CCn) upstream of the turbine, the method including steps of automatic control between controllable quantities specific to the supercharging stage (speed of rotation (ωn) of the electric machine, amount of fuel injected (Qinjn) into the combustion chamber, position (VGTn) of a variable geometry of the turbine) and measurable quantities specific to the supercharging stage (temperature (Tchn) of the combustion chamber, pressure P in-n downstream of the compressor and pressure Pout-n upstream of the turbine) according to the relations: a) Pin-n = fn(ωn); b) Pout-n = gn(VGTn); and c) Tchn = hn(Qinjn); fn, gn and hn depending on the dimensioning and positioning of the supercharging stage n in question, and n being between 2 and m.

Description

DESCRIPTION TITLE: METHOD FOR CONTROLLING A THERMODYNAMIC SYSTEM WITH AT LEAST TWO STAGES IN A MOTOR VEHICLE The present invention claims priority from French application No. 2407286 filed on July 4, 2024, the content of which (text, drawings and claims) is incorporated herein by reference. TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the field of control methods for thermodynamic systems with gas turbine cycle with cooled compression, regeneration and intermediate heating during expansion, of the turbomachine type, equipping a powertrain of a motor vehicle. PREVIOUS STATE OF THE ART

[0002] Gas turbine-type power converters are currently being studied for highly electrified powertrains, particularly those known as range extenders in production hybrid vehicles. Such a converter operates as an Auxiliary Power Unit (APU), where its role is to recharge the batteries of an electric vehicle. It is thus mechanically decoupled from the powertrain and therefore operates at its maximum efficiency.

[0003] In particular, a thermodynamic system with a gas turbine cycle and one or two supercharging stages is a device with strong potential for applications in motor vehicles, especially those with an electric traction motor. This cycle allows for very high efficiency as well as very high power density (i.e., high net specific work).

[0004] Currently, such thermodynamic "range extender" systems are essentially based on a supercharging stage implementing a compressor Cl, a combustion chamber CCI, and a turbine Tl, as illustrated in Figure 1. An electric machine EMG1 is driven by the turbine Tl and... The system is therefore located between the compressor Cl (also driven by the turbine Tl) and said turbine Tl. Such an architecture does not incorporate a device on the turbine Tl to manage the post-compression pressure P. It is a fixed-geometry turbine (FGTJ). Consequently, the system's actuators are limited to the quantity of fuel injected, the quantity of heat produced by Joule heating with an electrical resistance provided in the combustion chamber CCI, and the rotational speed of the electric machine EMG1.

[0005] Another existing thermodynamic system architecture is a two-stage supercharging thermodynamic system like the one described in document FR3134847, the principle of which is illustrated in Figure 2. In this document, the first stage, known as the high-pressure stage, consists of compressor Cl, combustion chamber CCI, turbine T1, and electric machine EMG1. The second stage, known as the low-pressure stage, consists of compressor C2 upstream of compressor Cl, combustion chamber CC2, turbine T2, both downstream of turbine T1, and electric machine EMG2. Again, turbines T1 and T2 are fixed-geometry turbines. With such a two-stage thermodynamic system, the efficiency is theoretically better, but the control and operation of the system is more complex. Indeed, in addition to the actuators of the first-stage system already mentioned, there are those of the second stage, which are similar. DESCRIPTION OF THE INVENTION

[0006] The invention aims to remedy all or part of the drawbacks of the prior art by proposing in particular a solution enabling optimal control of a thermodynamic system comprising two or more stages.

[0007] To this end, according to a first aspect of the invention, a method for controlling a thermodynamic system with m supercharging stages, m being greater than or equal to 2, comprising a supercharging stage n including a turbine, an electric machine, a compressor and a combustion chamber upstream of the turbine, characterized in that the method includes control steps between controllable quantities specific to the supercharging stage n, namely a rotational speed (o n J of the electric machine, a quantity of fuel injected (Qinj n J in the combustion chamber and a position [VGTn] of a variable turbine geometry and measurable quantities specific to the boost stage n, which are a temperature (Tch n ) of the combustion chamber, a pressure Pin-n downstream of the compressor and a pressure Pout-n upstream of the turbine according to the relationships: where the equations f n , gn and h n depend on the sizing and positioning of the n supercharging stage in the m supercharging system and n is between 2 and m.

[0008] According to one embodiment, the m-stage supercharging thermodynamic system comprising a first supercharging stage including a first compressor, a first electric machine, a first turbine, and a first combustion chamber connected upstream to the first compressor and downstream to the first turbine, the process includes control steps between controllable quantities specific to the first supercharging stage, namely a rotational speed (on) of the electric machine, a quantity of fuel injected (Qinji) into the combustion chamber, and a position (VGTi) of a variable turbine geometry, and measurable quantities specific to the first supercharging stage, namely a temperature (Tchi) of the combustion chamber, an air flow rate (Qair) at the inlet of the m-stage supercharging thermodynamic system, and a pressure Pout-1 upstream of the first turbine, according to the relationships: where the equations fi, gi and hi depend on a sizing and positioning of the first supercharging stage in the m-stage supercharging system.

[0009] According to one embodiment, the equations depend on operating points of the thermodynamic system with m supercharging stages, operating points determined during a theoretical thermodynamic analysis of said thermodynamic system with m supercharging stages.

[0010] According to another aspect of the invention, a motor vehicle powertrain is provided comprising an electric traction machine, a traction battery and an m-stage supercharging thermodynamic system, as well as a computer which is arranged to implement a control method according to the invention having at least one of the preceding technical characteristics.

[0011] According to one embodiment, the thermodynamic system with m supercharging stages comprising a shaft connecting the turbine and the compressor, the electric machine is positioned between the turbine and the compressor.

[0012] According to one embodiment, the thermodynamic system with m supercharging stages comprising a shaft connecting the turbine and the compressor, the electric machine is at the end of said shaft either on the turbine side or on the compressor side.

[0013] According to one embodiment, the thermodynamic system with m supercharging stages includes a bypass in place of the turbine.

[0014] According to yet another aspect of the invention, a motor vehicle is planned comprising a powertrain having one of the preceding technical characteristics.

[0015] According to another aspect of the invention, a power generation station is planned, comprising a thermodynamic system with m supercharging stages, characterized in that it further comprises a computer which is arranged to implement a control method according to the invention having at least one of the preceding technical characteristics. BRIEF DESCRIPTION OF THE FIGURES

[0016] Other features and advantages of the invention will become apparent from the following description, with reference to the attached figures, which illustrate: [Fig. 1]: a functional diagram of an example of a single-stage thermodynamic system; [Fig. 2]: a functional diagram of an example of a two-stage thermodynamic system, of the IRReGT type [Intercooled Recuperative Reheat Gas Turbine); [Fig. 3]: a functional diagram of an example of stage n of a multi-stage supercharging thermodynamic system; [Fig. 4]: a schematic representation of an electrical energy production and storage circuit in a hybrid vehicle; [Fig. 5]: a model of a complex servo control of the TGV position control of the turbine Tl in a method of controlling the thermodynamic system of figure 1; and, [Fig. 6]: a model illustrating a control method for a two-stage thermodynamic system from Figure 2

[0017] For clarity, identical or similar elements are identified by identical reference symbols across all figures. DETAILED DESCRIPTION OF A METHOD OF IMPLEMENTATION

[0018] With reference to Figure 4, we will describe here an example of the integration of a gas turbine cycle thermodynamic system into the powertrain of a hybrid or electric vehicle, and more specifically within the electrical energy production and storage circuit of that vehicle. automobile. Such a thermodynamic system can notably function as an auxiliary power unit (APU) in the case of an electric vehicle. When this thermodynamic system operates as an auxiliary power unit in a steady-state configuration, it recharges the traction battery(ies) B of the vehicle's powertrain via electric machines (EMG 1 in Figure 1, or more specifically EMG1 and EMG2 in Figure 2). The battery is connected, via AC-DC power converters (DC-AC blocks in Figure 4), on one side to the thermodynamic system as an APU and, on the other side, to an electric traction machine (ELM) of the vehicle's powertrain. A drive chain of a known type then connects the electric traction machine to the wheels W of the vehicle.The APU also includes a computer arranged to be able to implement a method of controlling the thermodynamic system, such as the method of controlling a thermodynamic system according to the invention which will be described later.

[0019] We will now detail a thermodynamic system of the aforementioned gas turbine cycle type with reference to Figure 1. Figure 1 is a functional diagram of an example of a single-stage thermodynamic system 1.

[0020] As already described in the preamble to this description, the thermodynamic system 1 comprises a compressor Cl, a combustion chamber CCI, and a turbine Tl. It also includes an electric machine EMG1 driven by the turbine Tl and thus located on the same shaft between the compressor Cl (also driven by the turbine Tl) and the turbine Tl. The electric machine EMG1 operates in both motor and generator modes, that is, as a motor to drive and start the thermodynamic system 1, and as a generator to recover the energy produced by combustion. Here, the turbine Tl is a variable geometry turbine (VGT). In alternative embodiments, the electric machine EMG1 can be positioned anywhere on the shaft, for example, at the end of the shaft on the side of the turbine Tl or the compressor Cl.

[0021] Thermodynamic system 1 also includes a heat recovery unit TR (or heat exchanger). The heat recovery unit TR is located here. connected to compressor Cl upstream and to combustion chamber CCI downstream. The combustion chamber CCI is then connected to turbine Tl.

[0022] The thermodynamic system 1 further includes a recovery branch RB1 connecting the turbine Tl to the heat recovery unit TR and passing through it. The side of the heat recovery unit TR through which the recovery branch RB1 passes is called the hot side of the heat recovery unit, since a gas flow comes directly from the turbine Tl after having undergone combustion in the combustion chamber CCI. Conversely, the side of the heat recovery unit TR receiving compressed air from the compressor Cl, and from which the air is directed to the combustion chamber CCI, is called the cold side of the heat recovery unit.

[0023] The thermodynamic system is configured to allow gas flow between its various components. Generally, the gas flow follows the arrows shown in Figure 1, which connect the different components, and passes through them. Ambient air is first drawn into an air filter AF by compressor Cl. This filtered air then enters compressor Cl. The air is compressed there before entering the recuperator TR, specifically the cold side of the recuperator. In the recuperator TR, the air is preheated by the hot gases from the recovery branch RB1, which originate from the turbine outlet Tl. The air exiting the recuperator TR thus enters the combustion chamber CCI. At the outlet of the combustion chamber CCI, an expansion occurs in turbine Tl.At the outlet of the turbine Tl, the hot gases enter the hot side of the recuperator TR to preheat the air coming from the compressor Cl, i.e. the cold side of the recuperator TR.

[0024] With such a single-stage supercharging thermodynamic system 1, it is relatively easy to determine which quantities to control and which observation variables to operate said single-stage supercharging thermodynamic system 1. An air flow rate Qair, a post-compression pressure Ppost between the compressor Cl and the turbine Tl, and a temperature Tch in the combustion chamber CCI, here catalytic, are observable (because measurable) quantities using appropriate sensors. Control quantities include a rotational speed OEM of the electric machine EMG1, a position TGV of the variable geometry on the turbine Tl and a quantity of fuel injected Qinj at the level of an injector inj upstream of the combustion chamber CCI.

[0025] Thus the single-stage thermodynamic system 1 has four actuators which are the electrical preheating resistance of the combustion chamber CCI which is here catalytic, the injector inj upstream of the combustion chamber CCI, the electric machine EMG1 linked to the shaft of the turbine Tl and the compressor Cl and a TGV position of the variable geometry on the turbine Tl.

[0026] On the other hand, a single-stage thermodynamic system control method will control quantities to be controlled, namely an air flow rate, Qair, a pressure at the compressor outlet Cl, Ppost comp and a temperature of the combustion chamber CCI, Tch.

[0027] A compressor, such as compressor Cl, is represented within a bond graph as essentially a transformer (or a modulated transformer). As a reminder, a bond graph—also called a link graph or bond graph in English—is a graphical representation of a physical dynamic system (here, compressor Cl) that depicts energy transfers within the system. Bond graphs are based on the principle of conservation of power. The links in a bond graph are symbols that represent energy flows. For compressor Cl, the inputs to the bond graph are a pressure ratio Pair / Ppost comp (a force in the bond graph sense) and the rotational speed OEM (a flux in the bond graph sense).The outputs of the linkage graph are a resisting torque of the compressor Cl (a force in the sense of the linkage graph) and the air flow rate Qair (a flow in the sense of the linkage graph).

[0028] For thermodynamic system 1, observable and controllable quantities are associated as follows.

[0029] The airflow is obtained by controlling the speed OEM of the electric machine EMG1, which then imposes a rotational speed of the compressor Cl. The TGV position of the turbine Tl strongly influences the pressure at the compressor outlet. Ppost comp, therefore the pressure ratio and also the air flow rate Qair produced. However, the control process allows control to be ensured in very large part by the rotation speed OEM, which is sufficient to reach the setpoint air flow rate Qair: Qair=f(cûEM).

[0030] The TGV position is taken into account by adapting the regulation of the air flow rate Qair by controlling the compressor Cl. In this case, the variation of the TGV position is treated as a perturbation of the air flow rate control Qair. The pressure Ppost comp between the compressor Cl and the turbine Tl is mainly obtained by controlling the TGV position of the turbine Tl: Ppost comp=g(VGT).

[0031] It should be noted that the amount of fuel injected (Qinj) and the air flow rate (Qair) supplied by the compressor (Cl) also play a role in the variation of the post-compression pressure (Ppost comp). The amount of fuel injected and the air flow rate can be taken into account by the control method, if necessary, in appropriate adjustments when regulating the downstream post-compression pressure (Ppost comp) of the compressor (Cl). In this case, the variation in the amount of fuel is treated as a disturbance in the control of the post-compression pressure (Ppost comp).

[0032] The combustion chamber temperature Tch is largely controlled by the amount of fuel injected Qinj. It should be noted that this amount of fuel injected Qinj is highly dependent on the efficiency of the heat recovery unit TR which allows heat exchange between the exhaust and the airflow exiting the compressor Cl: Tch=h(Qinj).

[0033] A consideration of the heat exchange delivered by the heat recovery unit TR can be integrated into a regulation adapted to this heat exchange when controlling the temperature Tch of the combustion chamber by the thermodynamic system control process 1. In this case, a quantity of heat exchanged between the heat recovery unit and the air entering the combustion chamber CCI is treated as a disturbance in the control of the combustion chamber temperature Tch.

[0034] In summary, the quantities to be controlled are measurable via suitable sensors, and the associated actuators can be represented in the following form:

[0036] Ppost comp = g(VGT)

[0037] T ch = h(Q inj )

[0038] Each variable to be controlled is governed by a simple or complex control system using the thermodynamic system control method 1, depending on whether or not, for example, a disturbance rejection is taken into account. An illustrative example is shown in Figure 5, which depicts a disturbance rejection for controlling the TGV position of turbine T1.

[0039] The functions [f, g, h) are dependent on the sizing of the different components of the thermodynamic system 1 and are based on the search for the operating points of said thermodynamic system 1 resulting from a theoretical thermodynamic analysis of said thermodynamic system 1. This theoretical thermodynamic analysis is known in itself and is carried out prior to the development of the control method of the thermodynamic system 1.

[0040] Now, with reference to Figure 2, we will describe a two-stage gas turbine cycle thermodynamic system 2, of the IRReGT [Intercooled Recuperative Reheat Gas Turbine] type, on which an embodiment of a thermodynamic system control method is implemented.

[0041] Such a thermodynamic system comprises two supercharging stages. The first stage includes a first compressor C2 and a first turbine T2. The second stage includes a second compressor C1 and a second turbine T1. More specifically, the first stage forms a "low-pressure" stage, and the second stage forms a "high-pressure" stage. Here, both turbines T1 and T2 are variable-geometry turbines.

[0042] The two supercharging stages are electrified here, meaning that each includes an electric machine EMG1, EMG2 operating simultaneously in mode The electric machine EMG1, EMG2 acts as both a motor to drive and start the thermodynamic system 2, and as a generator to recover the energy produced by combustion. The electric machine EMG1, EMG2 is positioned anywhere on a shaft connecting the compressor C1, C2 and the turbine T1, T2, for example, at the end of the shaft on the side of the turbine or compressor C1, or between the turbine and the compressor.

[0043] The thermodynamic system 2 further comprises two combustion chambers, CCI and CC2, and a flow cooler IC (also called an air-to-air or air-to-water heat exchanger, or simply an intercooler). The flow cooler IC is positioned between and connected to the first compressor Cl and the second compressor C2. Both combustion chambers, CCI and CC2, are catalytic combustion chambers. The first combustion chamber, CC2, incorporates an electric heating element.

[0044] Thermodynamic system 2 further includes a heat recovery unit TR (or heat exchanger). The heat recovery unit TR is connected to the second compressor Cl upstream and to the second combustion chamber CCI downstream. Thermodynamic system 2 includes a fuel injector (not shown in Figure 2) upstream of the second combustion chamber CCI. The second combustion chamber CCI is then connected to the second turbine T1.

[0045] The first combustion chamber CC2 is connected to both turbines, specifically to the second turbine T1 upstream and the first turbine T2 downstream. Thermodynamic system 2 includes a fuel injector (not shown in Figure 2) upstream of the first combustion chamber CC2. This fuel injector injects fuel into the gas stream from the second turbine T1 before it enters the first combustion chamber CC2.

[0046] The thermodynamic system further includes a recovery branch RB1 connecting the first turbine T2 to the heat recovery unit TR and passing through it. The side of the heat recovery unit TR through which the recovery branch RB1 passes is called the hot side of the heat recovery unit, since a gas flow comes directly from it. of the first turbine T2 after having undergone a second combustion in the combustion chamber CC2. In contrast, the side of the recuperator TR which receives compressed air from the compressor Cl, and from which the air is directed to the second combustion chamber CCI is called the cold side of the recuperator.

[0047] The use of a first CC2 combustion chamber (for reheat) between the turbines increases the power density, which reduces the air flow required at the same power and reduces the size of the thermodynamic system 2.

[0048] Thermodynamic system 2 is configured to allow a gas flow between its various components. Generally, the gas flow follows the arrows shown in Figure 2, which connect the different components, and passes through them. Ambient air is first drawn into an air filter AF by compressor C2. This filtered air enters compressor C2. There, the air is compressed before entering the flow cooler IC, where it is cooled. It then enters compressor Cl, where it is compressed a second time before entering the heat recovery unit TR, specifically the cold side of the heat recovery unit TR. In the heat recovery unit TR, the air is preheated by the hot gases from the recovery branch RB1, which originate from the outlet of turbine T2. The air exiting the heat recovery unit TR thus enters the second combustion chamber CCI.At the outlet of the second combustion chamber CCI, an initial expansion occurs in the second turbine T1 (high pressure), followed by a reheating phase in the first combustion chamber CC2 before entering the first turbine T2 for a second expansion. At the outlet of the first turbine T2, the hot gases enter the hot side of the recuperator TR to preheat the air coming from the second compressor Cl, i.e., the cold side of the recuperator TR.

[0049] It should be noted that, in thermodynamic system 2, the second catalytic CCI combustion chamber is subjected to the highest pressure and does not have an electrical heating resistance as in the single-stage architecture of thermodynamic system 1 previously described.

[0050] We will now describe a method for controlling a thermodynamic system 2.

[0051] Initially, we identified, at least partially, within thermodynamic system 2, an architecture as close as possible to the architecture of the single-stage thermodynamic system 1 described earlier. This identification is represented by a dashed outline in Figure 2. Indeed, the second high-pressure supercharging stage is similar to the single stage of thermodynamic system 1 described previously. Therefore, the equivalences of the measurable quantities between these two architectures are:

[0052]

[0053]

[0054]

[0055]

[0056] The control process then retains similar, or even identical, control laws to those previously established with regard to the single-stage thermodynamic system 1, namely:

[0057]

[0058]

[0059]

[0060] It appears that the addition of a second supercharging stage (here the first low-pressure stage), adds, with regard to a single-stage thermodynamic system 1, a catalytic chamber CC2, a compressor C2, an electric machine EMG2 and a turbine T2, here with variable geometry.

[0061] In the two-stage thermodynamic system 2, we then consider a temperature Tch2 in the first combustion chamber CC2, outside the start-up phase of thermodynamic system 2 (which is managed with The heating electrical resistance is primarily a function of the amount of fuel injected (Qinj-LP). It should be noted that the air entering this second combustion chamber (CCI) is preheated, firstly, by the heat exchange from the heat recovery unit and, secondly, by the amount of fuel injected (Qinj-HP) (when the associated injector is activated) into the second combustion chamber (CCI) of the high-pressure turbocharger stage. Macroscopically, we have: ?ch2 = h2(Qi n j L p)

[0062] A consideration of the heat exchange delivered by the heat recovery unit can be integrated into a regulation adapted to this heat exchange when controlling the temperature Tch2 of the low pressure combustion chamber CC2.

[0063] It now remains to associate the last two controllable quantities identified, namely the speed O EM-LP of the electric machine EMG2 and the position VGTLP of the first turbine T2, with the quantities we wish to control using the thermodynamic system 2 control method. At this stage, we have:

[0064] Airflow rate: Q a t r — fi(ü>EM-HP^>

[0065] The pressure after the second compressor Cl: P3=

[0066] The temperature in the second CCI combustion chamber: T cfll =

[0067] The temperature in the first combustion chamber CC2: T ch2 = h2(Qinj LP ).

[0068] As a reminder, the measurable quantities are P2, P3, P4, Tchi, Tch2, and Qair, and the controllable quantities are CÛEM-LP, CÛEM-HP, VGTLP, VGTHP, Qinj-LP, and Qinj-HP. Therefore, the remaining controllable quantities are the rotational speed CÛEM-LP of the EMG2 electric machine in the low-pressure boost stage and the position VGTLP of the T2 turbine. The two remaining measurable quantities are the two pressures P2 and P4.

[0069] Associating the remaining measurable quantities with the remaining controllable quantities is done in an analogous manner, and the control process implements the following associations:

[0070] The pressure after the first compressor C2: P2=

[0071] The pressure before the first turbine T2: P4 = g2(VGT LP ).

[0072] The control method implementing all the preceding equations (fi, gi, hi, f2, g2, and I12) is modeled in Figure 6 with a simple control system. Complex control systems taking into account disturbances as indicated for the control method of the single-stage thermodynamic system 1 can be implemented in the control method of the two-stage thermodynamic system 2 shown in Figure 6.

[0073] The equations (fi, gi, hi, f2, g2 and I12) are dependent on the dimensioning of the different components of the thermodynamic system 2 and are based, as before, on the search for the operating points of said thermodynamic system 2 resulting from a theoretical thermodynamic analysis of said thermodynamic system 2. This theoretical thermodynamic analysis is known in itself and is carried out prior to the development of the control method of the thermodynamic system 2.

[0074] Referring to Figure 3, we consider a supercharging stage n comprising a compressor Cn, an electric machine EMGn, and a turbine Tn (here with variable geometry), all three components mounted on the same drive shaft. Furthermore, the supercharging stage n includes a catalytic combustion chamber CCn connected upstream of the turbine Tn. Within a thermodynamic system with m supercharging stages, the compressor Cn is directly or indirectly downstream of a compressor Cn+1 of the next lower supercharging stage n+1, and directly or indirectly upstream of a compressor Cn-1 of the next higher supercharging stage n-1. Similarly, the combustion chamber CCn is downstream of a turbine Tn-1 of the next higher supercharging stage. The turbine Tn is upstream of the combustion chamber n+1 of the supercharging stage just below n+1. n is between 2 and m.

[0075] Considering what has been previously described with regard to thermodynamic systems 1 and 2, the integration of the n-stage supercharging system into a control process for the m-stage thermodynamic system is based on three new actuators specific to the n-stage supercharging system (electrical machine speed EMGn, quantity of fuel injected into the combustion chamber CCn, and turbine position Tn) and three specific measurable quantities (combustion chamber temperature CCn, pressure downstream of the compressor Cn, and pressure upstream of the turbine Tn). The equations f n , gn and h n associated are:

[0076] The pressure after the compressor Cn: P in-n = f n (u> n ),

[0077] The pressure before the turbine Tn: P out-n = 9n(VGT n ), And

[0078] The temperature in the CCn combustion chamber is: T chn = h n(Qinjn).

[0079] As before, the equations (f n (gn, hn) are dependent on the sizing of the various components of the m-stage thermodynamic system and, as before, rely on the determination of the operating points of said m-stage thermodynamic system based on a theoretical thermodynamic analysis of said m-stage thermodynamic system. This theoretical thermodynamic analysis is known in itself and is carried out prior to the development of the control method for the m-stage thermodynamic system.

[0080] In general, in the absence of sensors to measure a quantity necessary for the operation of the control process of an m-stage thermodynamic system, "estimators" are used in place of these missing sensors.

[0081] The control methods described above can be used, mutatis mutandis, with the use of bypasses (wastegates in Anglo-Saxon terminology) in place of one or more Tn turbines of the system thermodynamics with two or more supercharging stages. The same applies to architectures having a compressor with an electric machine unrelated to the turbine, a turbine with or without VGT, with or without wastegate but coupled to an electric machine, or even part or all of the stages mounted on the same shaft are potential variants for which the method of controlling a thermodynamic system with at least two stages is usable, mutatis mutandis.

[0082] The control methods and the associated multi-stage supercharging thermodynamic system described above were used in the context of a powertrain integrated into a motor vehicle. However, they can also be applied in other installations such as fixed power generation plants.

[0083] Naturally, the invention described above is by way of example. It is understood that a person skilled in the art is capable of carrying out different embodiments of the invention without departing from its scope.

[0084] It is emphasized that all features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims

DEMANDS 1. A method for controlling a thermodynamic system with m supercharging stages, where m is greater than or equal to 2, comprising a supercharging stage n including a turbine (Tn), an electric machine (EMGn), a compressor (Cn), and a combustion chamber (CCn) upstream of the turbine, characterized in that the method includes control steps between controllable variables specific to the supercharging stage n, namely a rotational speed (on) of the electric machine and a quantity of fuel injected (Qinj). n ) in the combustion chamber and a position (VGT n ) of a variable turbine geometry and measurable quantities specific to the boost stage n such as a temperature (Tch n ) of the combustion chamber, a pressure Pin-n downstream of the compressor and a pressure Pout-n upstream of the turbine according to the relationships: b) Pout-n =S'nO^'Pn) > c) Tch n hn(.QînJn) > where the equations f n , gn and h n depend on the sizing and positioning of the n supercharging stage in the m supercharging system and n is between 2 and m.

2. The method according to claim 1, characterized in that, the thermodynamic system with m supercharging stages comprising a first supercharging stage including a first compressor (Cl), a first electric machine (EMG1), a first turbine (Tl) and a first combustion chamber (CCI) connected upstream to the first compressor and downstream to the first turbine (Tl), the method includes control steps between controllable quantities specific to the first supercharging stage, namely a rotational speed (oi) of the electric machine, a quantity of fuel injected (Qinji) into the combustion chamber and a position (VGTi). of a variable turbine geometry and measurable quantities specific to the first stage of supercharging, namely a combustion chamber temperature (Tchi), an air flow rate (Qair) at the inlet of the thermodynamic system with m supercharging stages, and a pressure P ou ti upstream of the first turbine according to the relationships: ) ; where the equations fi, gi and hi depend on a sizing and positioning of the n supercharging stage in the m supercharging system.

3. A method according to any one of claims 1 to 2, characterized in that the equations depend on operating points of the m-stage supercharging thermodynamic system, operating points determined during a theoretical thermodynamic analysis of said m-stage supercharging thermodynamic system.

4. Powertrain for motor vehicle comprising an electric traction machine (ELM), a traction battery (B) and an m-stage supercharging thermodynamic system, characterized in that it further comprises an APU which is arranged to implement a control method according to any one of claims 1 to 3.

5. Powertrain according to claim 4, characterized in that, the thermodynamic system with m supercharging stages comprising a shaft connecting the turbine (Tn) and the compressor (Cn), the electric machine (EMGn) is positioned between the turbine (Tn) and the compressor (Cn).

6. Powertrain according to claim 4, characterized in that the thermodynamic system with m supercharging stages comprising a shaft connecting the turbine (Tn) and the compressor (Cn), the electric machine (EMGn) is at the end of said shaft either on the turbine side (Tn), or on the compressor side [Cn].

7. Powertrain according to any one of claims 4 to 6, characterized in that the thermodynamic system with m supercharging stages includes a bypass in place of the turbine (Tn).

8. Motor vehicle, characterized in that it comprises a powertrain according to any one of claims 4 to 7.

9. Electricity production station comprising a thermodynamic system with m supercharging stages, characterized in that it further comprises a computer which is arranged to implement a control method according to any one of claims 1 to 3.

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