METHOD FOR CONTROLLING A THERMODYNAMIC SYSTEM with at least two stages of a motor vehicle

Abstract

The invention relates to a method for controlling a thermodynamic system with m supercharging stages, m ≥ 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. The method includes control steps between controllable quantities specific to the supercharging stage (rotational speed (wn) of the electric machine, quantity of fuel injected (Qinjn) into the combustion chamber, position (VGTn) of a variable turbine geometry) and measurable quantities specific to the supercharging stage (temperature (Tchn) of the combustion chamber, pressure Pin-n downstream of the compressor, and pressure Pout-n upstream of the turbine) according to the relationships: fn, gn, and hn, depending on the sizing and positioning of the considered supercharging stage n, and n is between 2 and m. Figure 3

Description

Title of the invention: CONTROL METHOD A thermodynamic system with at least two floors of a motor vehicle Technical field of the invention

[0001] The invention relates to the field of methods for controlling thermodynamic systems with a gas turbine cycle with cooled compression, regeneration and intermediate heating during expansion, of the turbomachine type, equipping a powertrain of a motor vehicle. Prior 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 point.

[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 machine. This cycle makes it possible to achieve 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 employing a compressor Cl, a combustion chamber CCI, and a turbine Tl, as illustrated in [Fig. 1]. An electric machine EMG1 is driven by the turbine Tl and 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 (FGT). 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 such as that described in document FR3134847, the principle of which is illustrated in [Fig. 2]. In that 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 management 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 comprises control steps between controllable quantities specific to the supercharging stage n, namely a rotational speed (wn) of the electric machine, a quantity of fuel injected (Qinjn) into the combustion chamber and a position (VGTn) of a variable geometry of the turbine, and measurable quantities specific to the supercharging stage n, namely a temperature (Tchn) 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: æ ; b. ; Tchn = hn(Qinjn)

[0008] ; where the equations fn, gn and hn depend on a sizing and positioning of the n supercharging stage in the m supercharging system and n is between 2 and m.

[0009] According to one embodiment, the thermodynamic system with m supercharging stages 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 stages between controllable quantities specific to the first supercharging stage, namely a rotational speed (wJ) of the electric machine, a quantity of fuel injected (Qinji) into the combustion chamber and a position (VGTi) of a variable geometry of the turbine, 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 thermodynamic system with m supercharging stages and a pressure Pout-1 upstream of the first turbine according to the relations: b. Pa^ = gl(VGT}); c. T^h^QinjJ-, • where the equations fj, gi and hi depend on a sizing and positioning of the first supercharging stage in the m-stage supercharging system.

[0010] 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.

[0011] According to another aspect of the invention, a motor vehicle powertrain is provided comprising an electric traction machine, a traction battery and a thermodynamic system with m supercharging stages, 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.

[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 positioned between the turbine and the compressor.

[0013] 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.

[0014] According to one embodiment, the thermodynamic system with m supercharging stages includes a bypass in place of the turbine.

[0015] According to yet another aspect of the invention, a motor vehicle is provided comprising a powertrain having one of the preceding technical characteristics.

[0016] According to another aspect of the invention, an electricity production station is provided 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

[0017] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate: • [Fig.l]: a functional diagram of an example of a single-stage thermodynamic system; • [Fig. 2]: A functional diagram of an example of a thermodynamic system double-stage, of the IRReGT (Intercooled Recuperative Reheat Gas Turbine) type; • [Fig. 3]: a functional diagram of an example of stage n of a system multi-stage supercharging thermodynamics; • [Fig. 4]: a schematic representation of a production circuit and of electrical energy storage in a hybrid vehicle; • [Fig. 5]: A model of a complex control system of the TGV position of the turbine Tl in a method of controlling the thermodynamic system of the [Fig.l]; and, • [Fig. 6]: a model illustrating a system control process two-stage thermodynamics of the [Fig.2]

[0018] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of a method of implementation

[0019] With reference to [Fig. 4], we will describe here an example of the integration of a gas turbine cycle thermodynamic system into a powertrain of a hybrid or electric motor vehicle, and more specifically within an electrical energy production and storage circuit of this motor vehicle. Such a thermodynamic system can notably operate as an auxiliary power unit (APU) in the case of an electric motor vehicle. When this thermodynamic system operates as an auxiliary power unit in a stabilized mode, it recharges the traction battery(ies) B of the motor vehicle's powertrain via electric machines (EMG 1 in [Fig. 1], or more specifically EMG1 and EMG2 in [Fig. 2]). The battery is connected, on the one hand, to the thermodynamic system via alternating current-to-direct current electrical energy converters (DC-AC blocks in [Fig. 4]). The APU is connected 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 further includes a computer arranged to implement a method for controlling the thermodynamic system, such as the method for controlling a thermodynamic system according to the invention, which will be described later.

[0020] We will now detail a thermodynamic system of the aforementioned gas turbine cycle type with reference to [Fig. 1]. [Fig. 1] is a functional diagram of an example of a single-stage thermodynamic system 1.

[0021] As already described in the preamble to the description, the thermodynamic system 1 comprises, here, a compressor Cl, a combustion chamber CCI, and a turbine Tl. It also includes an electric machine EMG1 driven by the turbine Tl and is therefore located on the same shaft between the compressor Cl (also driven by the turbine Tl) and said turbine Tl. The electric machine EMG1 operates both as a motor and a generator, 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 is positioned anywhere on the shaft, for example, at the end of the shaft on the side of the turbine Tl or the compressor CL.

[0022] The thermodynamic system 1 further comprises a heat recovery unit TR (or heat exchanger). The heat recovery unit TR is connected to the compressor Cl upstream and to the combustion chamber CCI downstream. The combustion chamber CCI is then connected to the turbine TL

[0023] The thermodynamic system 1 further includes a recovery branch RB1 connecting the turbine T1 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 T1 after having undergone combustion in the combustion chamber CCI. In contrast, 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.

[0024] The thermodynamic system is configured to allow a gas flow between its various component elements. Generally, the gas flow follows the arrows illustrated in [Fig. 1] which connect the different components and passes through them. Ambient air is first drawn into an air filter AF by the compressor CL. This filtered air enters the compressor CL. The air is compressed there before entering the recuperator TR, specifically on the cold side. of the recuperator. In the recuperator TR, the air is preheated by the hot gases from the RB1 recovery branch coming from the outlet of the turbine 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 the 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.

[0025] 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 suitable sensors. Control quantities are a rotational speed wEM of the electric machine EMG1, a position TGV of the variable geometry on the turbine Tl, and a quantity of fuel injected Qinj at an injector inj upstream of the combustion chamber CCI.

[0026] 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.

[0027] On the other hand, a control method for the single-stage thermodynamic system 1 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.

[0028] A compressor, such as compressor Cl, is represented within a bond graph as being, overall, a transformer (or a modulated transformer). As a reminder, a bond graph—also called a link graph or bond graph in Anglo-Saxon terminology—is a graphical representation of a physical dynamic system (here, compressor Cl) that represents the 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, in this case, 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 wEM (a flow 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).

[0029] For the thermodynamic system 1, the observable and controllable quantities are associated as follows.

[0030] The air flow rate is obtained by controlling the speed wEM 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, and therefore the pressure ratio and also the air flow rate Qair produced. However, the control method allows for control that is largely ensured by the rotational speed wEM, which is sufficient to reach the setpoint air flow rate Qair: Qair=f(coEM).

[0031] The TGV position is taken into account by means of an adapted regulation of the air flow rate Qair by a compressor CL regime. 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).

[0032] It should be noted that the quantity of fuel injected Qinj and the air flow rate Qair supplied by the compressor Cl also play a role in the variation of this post-compression pressure Ppost-com. The quantity of fuel injected and the air flow rate can be taken into account by the control method, if necessary, in appropriate regulations when controlling the downstream post-compression pressure Ppost-com of the compressor CL. In this case, the variation in the quantity of fuel is treated as a disturbance in the control of the post-compression pressure Ppost-com.

[0033] The combustion chamber temperature Tch is largely controlled by the quantity of fuel injected Qinj. It should be noted that this quantity of fuel injected Qinj is very strongly 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).

[0034] 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 method of controlling the thermodynamic system 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 perturbation of the control of the temperature of the combustion chamber Tch.

[0035] In summary, the quantities to be controlled are measurable via suitable sensors, and the associated actuators can be represented in the form:

[0036]

[0037] P pOSf comp — g (VGT)

[0038] T^h^j)

[0039] Each variable to be controlled is controlled through a simple or complex control system by the thermodynamic system control method 1, depending on whether or not, for example, a rejection of the disturbance to be considered is taken into account. An illustrative example is shown in [Fig. 5], where a rejection of the disturbance for the control of the TGV position of the turbine T1 is represented.

[0040] The functions (f, g, h) are dependent on a dimensioning 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.

[0041] Now with reference to [Fig.2], we will describe a thermodynamic system 2 of the two-stage gas turbine cycle type, of IRReGT (Intercooled Recuperative Reheat Gas Turbine) type, on which an embodiment of a method for controlling the thermodynamic system is implemented.

[0042] Such a thermodynamic system comprises two supercharging stages. The first stage comprises a first compressor C2 and a first turbine T2. The second stage comprises a second compressor C1 and a second turbine TL. 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.

[0043] The two supercharging stages are electrified here, meaning that each includes an electric machine EMG1, EMG2 operating both as a motor and a generator, that is, as 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.

[0044] The thermodynamic system 2 further comprises two combustion chambers CCI and CC2, and a flow cooler IC (also called an air-to-air heat exchanger, or air-to-water heat exchanger, or in English, an "intercooler"). The flow cooler IC is positioned between and connected to the first compressor Cl and the second compressor C2. The two combustion chambers CCI and CC2 are catalytic combustion chambers. The first combustion chamber CC2 has an electric heating element.

[0045] The 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. The thermodynamic system 2 includes a fuel injector (not shown in [Fig. 2]) upstream of the second combustion chamber CCI. The second combustion chamber CCI is then connected to the second turbine TL

[0046] The first combustion chamber CC2 is connected to the two turbines, namely, in particular, to the second turbine T1 upstream and to the first turbine T2 downstream. The thermodynamic system 2 includes a fuel injector (not shown in [Fig. 2]) upstream of the first combustion chamber CC2. This fuel injector allows fuel to be injected into the gas stream from the second turbine T1 before it enters the first combustion chamber CC2.

[0047] The thermodynamic system further comprises 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 the first turbine T2 after having undergone a second combustion in the combustion chamber CC2. In contrast, the side of the heat recovery unit TR receiving 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 heat recovery unit.

[0048] The use of a first combustion chamber CC2 (for reheat) between the turbines makes it possible to increase the power density, which makes it possible to reduce the air flow required at the same power and to reduce the size of the thermodynamic system 2.

[0049] The thermodynamic system 2 is configured to allow a gas flow between its various component elements. Generally, the gas flow follows the arrows illustrated in [Fig. 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. The air is compressed there before entering the flow cooler IC, where it is cooled. It then enters compressor C1, 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, originating from the outlet of turbine T2. The air exiting the heat recovery unit TR thus enters the second combustion chamber CCI.At the exit of the second combustion chamber CCI, a first expansion occurs in the second turbine Tl (high pressure) then a heating phase in the first combustion chamber CC2 before entering. in the first turbine T2 to undergo 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.

[0050] It should be noted that, in thermodynamic system 2, the second catalytic ICC 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.

[0051] We will now describe a method for controlling a thermodynamic system 2.

[0052] 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 previously. This identification is indicated by a dashed outline in [Fig. 2]. Indeed, the second high-pressure supercharging stage is close to the single stage of thermodynamic system 1 described previously. Therefore, the equivalences of the measurable quantities between these two architectures are:

[0053] Peomp-HP ~ P3

[0054] Tch- Tch HP - Tch j

[0055] Q. = Q. . „p

[0056] = MEM_HP

[0057] The control method then retains similar, or even identical, control laws to those previously established with regard to the single-stage thermodynamic system 1, namely:

[0058] = ^EM-HP ) ~ ( ^EM-HP )

[0059] P^g(VGTHF}=gï(VGTHP)

[0060] Tchi-h(QnHp} =^\[Qinj.Hp)

[0061] 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.

[0062] In the two-stage thermodynamic system 2, we consider that a temperature Tch2 in the first combustion chamber CC2, outside the start-up phase of the thermodynamic system 2 (which is managed with the electric heating element), is a function primarily of the amount of fuel injected Qinj-LP. It should be noted that the air entering this second combustion chamber CCI is preheated, on the one hand, by the heat exchange of the recuperator. thermal and, on the other hand, by the quantity of fuel injected Qinj-HP (when the associated injector is activated) into the second combustion chamber CCI of the high-pressure supercharger stage. Macroscopically, we have:

[0063] 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.

[0064] It now remains to associate the last two identified controllable quantities, namely the Wemlp speed of the EMG2 electric machine and the VGTLP position of the first turbine T2, with the quantities that we wish to control using the thermodynamic system 2 control method. At this stage, we have:

[0065] The air flow rate: ( ^em-hp) ,

[0066] The pressure after the second compressor Cl: P3 = (VGTHP),

[0067] The temperature in the second combustion chamber CCI: - ^1 ( Qin j-HP ) ' and

[0068] The temperature in the first combustion chamber CC2: Tch2 - ^2 ( Q^j LP)-

[0069] Now, as a reminder, the measurable quantities are P2, P3, P4, Tchi, Tch2 and Qair, and The controllable quantities are coEm_LP, cüem hP. VGTLP, VGTHP, Qinj lp, and Qinj. HP. Therefore, the remaining controllable quantities are the rotational speed coem ip 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.

[0070] Associating the remaining measurable quantities with the remaining controllable quantities is done in an analogous manner, and the control method implements the following associations:

[0071] The pressure after the first compressor C2: P y = ( <^em-lp ) ,et

[0072] The pressure before the first turbine T2: P4 = g-, ( VGTLP ).

[0073] The control method implementing all the preceding equations (fb gb hb f2, g2 and h2) is modeled in [Fig. 6] with a simple control system. Complex control systems taking into account disturbances as indicated with regard to the control method of the single-stage thermodynamic system 1 can be provided in the control method of [Fig. 6] of the two-stage thermodynamic system 2.

[0074] The equations (fb gb hb f2,g2 and h2) are dependent on the dimensioning of the different components of the thermodynamic system 2 and are based, as Previously, 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.

[0075] With reference to [Fig. 3], we consider a supercharging stage n comprising a compressor Cn, an electric machine EMGn, and a turbine Tn (here with variable geometry), the three components being 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 next lower supercharging stage n+1. n is between 2 and m.

[0076] Considering what has been previously described with regard to thermodynamic systems 1 and 2, the integration of the supercharging stage n within a method for controlling the m-stage thermodynamic system is based on three new actuators specific to the supercharging stage n (speed of the electric machine EMGn, quantity of fuel injected into the combustion chamber CCn, and position of the turbine Tn) and three specific measurable quantities (temperature of the combustion chamber CCn, pressure downstream of the compressor Cn, pressure upstream of the turbine Tn). The associated equations fn, gn, and hn are:

[0077] The pressure after the compressor Cn: Pin.n = f ( Mn ),

[0078] The pressure before the turbine Tn: Pout.n — Sn( VGT„), and

[0079] The temperature in the combustion chamber CCn is: 7^ = hn ( Qin jn ).

[0080] As before, the equations (fn, gn, hn) depend 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 resulting from 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.

[0081] Generally, in the absence of sensors to measure a quantity necessary for the operation of the control process of a system In m-stage thermodynamics, "estimators" are used in place of these missing sensors.

[0082] 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 turbines Tn of the two- or more-stage supercharging thermodynamic system. The same applies to architectures having a compressor with an electric machine unrelated to the turbine, a turbine with or without a VGT, with or without a wastegate but coupled to an electric machine, or even some or all of the stages mounted on the same shaft. These are potential variants for which the control method of a thermodynamic system with at least two stages can be used, mutatis mutandis.

[0083] The control methods and the associated m-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 stations.

[0084] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

[0085] 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 make such combinations impossible or meaningless.

Claims

1.

2. Demands 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 (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 quantities specific to the supercharging stage n, namely a rotational speed (wn) of the electric machine, a quantity of fuel injected (Qinjn) into the combustion chamber and a position (VGTn) of a variable geometry of the turbine, and measurable quantities specific to the supercharging stage n, namely a temperature (Tchn) of the combustion chamber, a pressure Pin-n downstream of the compressor and a pressure Pout-n upstream of the turbine according to the relations: a- -^in-n — fn ( , b- ; c. Tc^hn(Qinjn); where the equations fn, gn and hn depend on a sizing and positioning of the n supercharging stage in the m supercharging system and n is between 2 and m. 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 (wi) 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 and an air flow rate (Qair) at the system inlet. thermodynamics at m supercharging stages and a pressure P„ul i upstream of the first turbine according to the relations: æ ; b. P^g^VGTJ ; c. T^h^QinjJ ; where the equations fb gi and hi depend on a dimensioning and positioning of the supercharging stage n in the supercharging system with m supercharging stages.

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 side of the turbine (Tn), or on the side of the compressor (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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