Device for controlling a fuel cell anode line

Abstract

The invention relates to a fuel cell (1) comprising a stack (E) of electrochemical cells (T1, T2) provided with at least one anode feed header (C1, C2) and one anode discharge header (C3), the fuel cell (1) being intended to supply a load with electric current and comprising at least one anode line passing through the stack (E) of electrochemical cells. The cell comprises a control device (K) for controlling a fuel fluid injection group with a view to regulating the pressure of the fuel fluid in the line so that it conforms to a given setpoint pressure. The control device (K) is configured so as to evaluate a limited number of injection control profiles over a predetermined time horizon.

Description

fuel cell anodic line control device FIELD OF INVENTION

[0001] The present invention relates to a control device for an anodic line of a fuel cell, in particular a fuel cell of the "proton exchange membrane" type. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] In a fuel cell designed to supply an electric current to a load, and more particularly in a fuel cell of the "proton exchange membrane" type, the fluidic network passing through the electrochemical cells composing the cell and allowing the contact of the fuel fluid (typically hydrogen) with one of the electrodes (the anode) of the cells is designated as the "anode line".

[0003] This line extends from a first controllable valve, associated with a fuel fluid source and fluidically connected to a fuel cell supply manifold, to a second controllable discharge valve, which is itself fluidly connected to a fuel cell discharge manifold. US documents 2018 / 175419, 2016 / 133970, and 2022 / 293974 propose fuel cells comprising an anodic line equipped with an injection group consisting of a plurality of injectors.

[0004] The electrochemical reaction occurring in the battery cells generates the electric current drawn by the load.

[0005] It is necessary to supply these cells with reactive fluids in quantities adjusted to the electric current, which can naturally vary. For obvious reasons of mechanical strength, the pressure of the reactive fluids, fuel and oxidizer, is balanced within a cell, so the fluid quantities are not necessarily the stoichiometric quantities of the electrochemical reaction. It is also necessary to remove unconsumed reactive fluids and residues from the chemical reaction occurring in the cells, particularly water produced on the anode side or migrating from that side.

[0006] To this end, the fuel cell is equipped with control devices connected to the first and second valves. These control devices are configured to regulate the fuel fluid pressure in the cells to a setpoint pressure and to control the removal of residues from these cells. The setpoint pressure is the pressure required to deliver the reactive fluids to the cells in quantities adjusted to the electrical current to be produced.

[0007] Document US20230129936 illustrates a conventional approach to regulation in which the first valve is of the "on or off" type, this type of valve being referred to as an "injector" in the remainder of this description.

[0008] In this conventional control approach, known as "bang-bang" or "hysteresis," a band is defined around a setpoint pressure within which the fluid pressure in the anodic line is allowed to vary. When the pressure reaches the upper or lower limit of this band, the fuel injector is triggered (opening or closing) to bring the pressure back into the desired range around the setpoint pressure.

[0009] This conventional approach, however, has limitations. Indeed, due to the bandwidth within which the fluid pressure is allowed to vary, the inherent inertia of the electrochemical process, and the delays introduced by the injector and any other actuators and sensors in the control loop, it is difficult to stabilize the line pressure around the setpoint, as the pressure tends to oscillate. This can be partially compensated for by operating the control device, and therefore the injector, at a very high frequency. This imposes a high computational load on the control device and excessive stress on the injector, which is obviously undesirable for reliability reasons.

[0010] Alternative control approaches have been considered in the prior art, but these approaches are highly dependent on the fuel cell architecture. They are not always suitable for an architecture without a recirculation pump, as such a pump allows the fuel fluid not consumed by the electrochemical reaction to be reinjected into the anodic line. SUBJECT OF THE INVENTION

[0011] One aim of the invention is to offer an alternative to prior art solutions. More specifically, one aim of the invention is to provide a fuel cell anode line control device that is simple to implement, suitable for a wide range of fuel cell architectures, and improves the quality of the regulation. BRIEF DESCRIPTION OF THE INVENTION

[0012] With a view to achieving one of these goals, the object of the invention proposes a fuel cell comprising a stack of electrochemical cells equipped with at least one anodic supply collector and at least one anodic discharge collector, the fuel cell being intended to supply an electric current to a load and comprising: at least one anodic line passing through the stack of electrochemical cells and in which a fuel fluid is capable of circulating, the anodic line extending: from a fuel fluid injection group fluidly connected to the anodic supply collector, the injection group comprising a plurality of injectors selectively controllable in on or off mode, an injection group control being defined by the number of selectively controlled injectors open among the plurality of injectors.to a controllable purge valve fluidically connected to the anodic evacuation manifold; a pressure sensor capable of providing a value representative of the fuel fluid pressure in the anodic line; a control device intended to develop, during successive calculation periods, the control of the injection group to be applied at the end of the calculation period in question in order to regulate the fuel fluid pressure in the anodic line so that it conforms to a given setpoint pressure, the control device being configured to evaluate a predetermined number of injection control profiles, a profile being composed of the injection group controls over a determined prediction horizon.

[0013] The control device is further configured to, during each calculation period: apply each injection control profile to a predictive model of anodic line pressure and calculate a predictive performance indicator associated with that injection control profile; select the injection control profile that optimizes the predictive performance indicator; extract from the selected injection control profile the injection group control to be applied to the injection group at the end of the calculation period.

[0014] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: the injection group controls composing an injection control profile are linked to each other; the injection group controls composing an injection control profile are all equal to each other; the predictive model of anodic line pressure links the anodic line pressure to the electrical current, to a purge valve control and to the injection group control; the predictive performance indicator incorporates constraints on the anodic line pressure, so that it tends to remain between a minimum pressure and a maximum pressure; the predictive performance indicator includes a time weighting term;The fuel cell further includes a supervisory unit configured to control the purge valve and apply the command provided by the control device to the injection group; the fuel cell comprises two injection groups respectively associated with two anodic feed manifolds of the electrochemical cell stack, defining two anodic lines extending to the purge valve, the supervisory unit being configured to apply the injection group command provided by the control device to one and / or the other of the two injection groups; the two injection groups have the same number of injectors; the injectors of one injection group have the same characteristics as the injectors of the other injection group; the pressure sensor is located at the anodic discharge manifold; the fuel cell is of the proton exchange membrane type;the fuel cell has no recirculation between the purge valve and the anodic feed manifold.

[0015] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which:

[0016]

[0017] Lare represents a fuel cell according to an implementation method;

[0018]

[0019]

[0020]

[0021] Figures 2a, 2b and 2c illustrate the operation of the battery;

[0022]

[0023]

[0024] Figures 3a and 3b compare, at two different operating points, the regulation of a battery according to the prior art and of a battery according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] This represents a fuel cell according to one embodiment. In this embodiment, the fuel cell retains the general architecture and operating principles of the cell described in document EP2707921. The invention is, of course, in no way limited to such an architecture, which is taken solely as an illustration of the principles of the invention.

[0026] As is well established in the field, a fuel cell is designed to supply an electric current to a load by electrochemically reacting reactive fluids, fuel and oxidizer, within a plurality of cells. The reactive fluids are usually in gaseous form and can be composed of hydrogen and air or hydrogen and an oxygen-rich gas.

[0027] The fuel cell comprises a stack E of electrochemical cells T1, T2 connected electrically and fluidically. Each cell in the stack E includes an anode, towards which the fuel fluid flows; a cathode, towards which the oxidizing fluid flows; and an electrolyte between the two, in this case a proton exchange membrane. At the ends of the stack E of cells T1, T2 are, on one side, an anode connected to a negative terminal to remove electrons, and on the other side, a cathode connected to a positive terminal. The load is connected to these terminals, and the electrons that form the electric current produced by the fuel cell flow from the anode to the cathode to power the load.

[0028] The E-stack is formed from two types of electrochemical cells, T1 and T2, which may be identical but are fueled separately. For ease of understanding, the two types of cells, T1 and T2, are shown side-by-side, but in practice, the two types are nested within the E-stack, alternating regularly between cells of type T1 and cells of type T2. A stack typically consists of several dozen or several hundred T1 and T2 cells.

[0029] The stack E is traversed by two anodic feed manifolds C1, C2 constituting means of distributing the fuel fluid on the anode side, respectively, of the first type cells T1 and the second type cells T2. Similarly, the stack E is traversed by an anodic drain manifold C3 constituting means of draining the residues of the electrochemical reaction that have accumulated on the anodic side of the cell (in particular water and nitrogen which do not participate in the reaction and which, on the contrary, tend to inhibit it).

[0030] One could consider equipping stack E with two anodic evacuation collectors, each collector allowing the collection of reaction products from each type of cell T1, T2, but such an arrangement is not mandatory. Similarly, for the sake of simplicity, the supply and evacuation means on the cathodic side of cells T1, T2 of stack E are not shown, although these means are of course present.

[0031] Continuing the description of the fuel cell 1 shown above, it is connected to a fuel fluid reservoir R, here hydrogen, via conduits. Other components can be added between the reservoir R and the fuel cell 1 to condition the fuel fluid in a way that promotes the electrochemical reaction occurring in cells T1 and T2 (filter, heat exchanger, compressor, etc.). In any case, the fuel fluid is delivered to two injection groups G1 and G2, which are respectively fluidically connected to the anodic feed manifolds C1 and C2 of the stack E.

[0032] Each injection group G1, G2 comprises a plurality of injectors arranged in a parallel configuration and selectively controllable in an on / off fashion, i.e., between an "open" and a "closed" mode. An injection group control Cd1, Cd2 (more simply "injection control" in the remainder of this description) is defined by the number of injectors selectively controlled in open mode among the plurality of injectors, the other injectors in the group being controlled in closed mode. Thus, depending on the number of injectors controlled open by the injection control, it is possible to vary the hydrogen flow rate injected into a type of cell from a zero flow rate, at which the injection control positions all injectors in closed mode, to a maximum flow rate, at which the injection control positions all injectors in open mode.

[0033] The number of injectors in each group G1,G2 can be arbitrary, typically between 2 and 10 injectors per group. For simplicity of implementation, in the implementation shown in the figure, the first injection group G1 and the second injection group G2 each have the same number N inj of injectors all exhibiting identical fluidic characteristics (such as the fluid flow characteristic for a pressure difference of 1 bar).

[0034] However, this should not be seen as a limitation and, in other implementations, the number of injectors in each group and the fluidic characteristics of the injectors may be different, as it is possible to control the two injection groups G1,G2 to allow the distribution of an identical flow rate in both types of cells T1,T2.

[0035] Stack 1 also includes a controllable purge valve Vp fluidically connected to the anodic discharge manifold C3 (or to a plurality of these manifolds, if stack E is equipped with such a plurality). When this purge valve Vp is controlled to be open, the residues of the electrochemical reaction collected from the anodic side of cells T1, T2 by the discharge manifold C3 can be discharged from stack E. This purge valve Vp is advantageously of the "on / off" type, and the purge valve control Cdp (more simply "purge control" in the remainder of this description) allows it to be controlled open or closed. However, in other implementations, the purge valve can be of the "proportional" type, and the purge control allows setting a degree of opening of this valve Vp between its fully open and fully closed positions.

[0036] Stack 1 can also be equipped with a cooling circuit allowing a heat transfer fluid to circulate in stack E in order to control its temperature.

[0037] The injection groups G1, G2 and the purge valve Vp which have just been described, as well as all the other undescribed elements of stack 1, are controlled by a supervisory device S. This device is implemented by elementary processing components (CPU, microcontroller, FPGA, memory, converters, input / output interfaces…) combined together.

[0038] The supervisory device S operates fuel cell 1. Specifically, it applies a first injection command Cd1, a second injection command Cd2, and a purge command Cdp to, respectively, the first injection group G1, the second injection group G2, and the purge valve Vp. The supervisory device S collects and stores in memory all measurements provided by the sensors with which fuel cell 1 is equipped, including the current I produced by fuel cell 1, the pressure measured by a pressure sensor P, and an injection command Cd provided by a control device K, which will be detailed in a later section of this description.

[0039] The supervision device S is specifically configured in hardware and / or software to operate stack 1 according to three different configurations, respectively represented in figures 2a, 2b, 2c.

[0040] In the first configuration shown in the figure, the first injection group G1 is controlled to supply a flow of fuel fluid to the first-type cell T1. Conversely, the second injection group G2 is controlled to be fully closed. The purge valve Vp is also controlled to be closed. The fuel fluid therefore flows along a first anodic line extending from the first injection group G1 to the purge valve Vp, through the first-type cell T1, and also along a second anodic line extending from the purge valve Vp to the second injection group G2 through the second-type cell T2.

[0041] In a second configuration shown in the figure, the first injection group G1 is controlled to be fully closed, and the second injection group G2 is controlled to supply a flow of fuel fluid to the second-type cell T2. The purge valve Vp is also controlled to be closed. The fuel fluid therefore flows along a first anodic line extending from the second injection group G2 to the purge valve Vp, through the second-type cell T2, and also along a second anodic line extending from the purge valve Vp to the first injection group G1, through the first-type cell T1.

[0042] In a third configuration shown in Figure 1, the first injection group G1 and the second injection group G2 are both controlled to supply the same fuel fluid flow rate to cells T1 and T2. The purge valve Vp is controlled to remain open. The fuel fluid thus flows along a first anodic line extending from the first injection group G1, through the first-type cell T1 and the purge valve Vp. It also flows along a second anodic line extending from the second injection group G2, through the second-type cell T2 and the purge valve Vp. This configuration allows the reaction residues to be ejected from the anodic portion of the cells and from fuel cell 1.

[0043] The monitoring device S is configured to repeatedly alternate between the first two configurations a certain number of times, followed by the third configuration. The previously cited document EP2707921 provides additional implementation methods for this architecture, which we will not reproduce here for the sake of brevity, and details all the advantages of this operating principle. In particular, the fuel cell in this implementation method is devoid of any recirculation between the purge valve Vp and the anode feed manifolds.

[0044] This description focuses primarily on the anodic line of the fuel cell 1, that is, the fuel flow extending, in one direction or the other, from an injection group to the purge valve Vp, through a cell T1,T2 of one of two types. As previously mentioned, a fuel cell compatible with the present invention may have several anodic lines, which in this case intersect at the purge valve Vp and therefore have identical or very similar pressures. However, the invention can also be used in a simpler architecture, with only a single anodic line, and / or possibly a recirculation line, between the purge valve Vp and the anodic feed manifolds, without passing through one of the cells of the stack E.

[0045] In all cases, and as stated in the introduction to this request, the aim is to control the fuel fluid pressure in the anodic lines, and more specifically in cells T1 and T2 of fuel cell 1, so that it conforms to a setpoint pressure P ref This setpoint pressure P ref This is the pressure that allows the reactive fluids to be delivered to the cells in quantities adjusted to the electrical current to be produced. The setpoint pressure (P) ref can be developed by the supervisory device S, for example using a function or a table allowing the setpoint pressure P to be associated for pile 1 ref to a given current.

[0046] To enable this pressure regulation of the anodic line, the fuel cell 1 includes a pressure sensor KP capable of providing a value P representative of the fuel fluid pressure in this anodic line. In the implementation mode shown, this sensor KP is located in the section of conduit that separates the drain manifold C3 from the purge valve Vp.

[0047] Stack 1 also includes a control device K designed to generate, over successive computation periods, an injection command Cd. These computation periods can follow one another according to a predetermined sampling frequency. In the case of stack 1 in the chosen implementation mode, this sampling frequency can be on the order of 100 Hz, or more generally between 10 Hz and 1 kHz, defining a computation period of between 1 millisecond and 100 milliseconds.

[0048] Like the supervisory device S, the control device K is implemented by combining elementary processing components (CPU, microcontroller, FPGA, memory, converters, input / output interfaces, etc.). Although the control device K and the supervisory device S are shown as two separate devices for clarity, it is entirely possible for their respective functions to be implemented by a single device; for example, the control device K could be implemented by the elementary processing components that make up the supervisory device S.

[0049] The injection command Cd is provided by the control device K to the supervisory device S. The latter uses this injection command Cd to generate the first injection command Cd1 and the second injection command Cd2, which are applied to the first and second injection groups G1 and G2, respectively, at the end of the calculation period. The injection command Cd provided by the control device K defines the number of injectors controlled in open mode in one or both of the injection groups G1 and G2, it being understood that injectors not controlled in open mode in an injection group are controlled in closed mode.

[0050] Thus, when the supervisory device S operates stack 1 in the first configuration, the supervisory device S: applies to the first injection group G1 the first injection command Cd1 set to the injection command Cd provided by the control device K; applies to the second injection group G2 a second injection command Cd2 which commands this group G2 to be fully closed. In other words, the second injection command is set to 0.

[0051] Similarly, when the supervisory device S operates stack 1 in the second configuration, the supervisory device S: applies to the first injection group G1 the first injection command Cd1, which commands this group G1 to be fully closed. The second injection command is therefore set to 0; applies to the second injection group G2 the second injection command Cd2, set to the injection command Cd provided by the control device K.

[0052] Finally, when the supervisory device S operates stack 1 in the third configuration, the supervisory device S: applies to the first injection group G1 the first injection command Cd1 fixed to the injection command Cd provided by the control device K; applies to the second injection group G2 the second injection command Cd2 fixed to the injection command Cd provided by the control device K.

[0053] We now present the principles implemented by the control device K to develop the injection control Cde, selectively applied to one and / or the other of the injection groups G1,G2 by the supervision device S.

[0054] First of all, we develop a model of the pressure P prevailing in the anodic lines of pile 1, the model being able to be expressed by an equation of state linking this pressure to the electric current I, to the purge control Cdp and to the injection control Cd.

[0055]

[0056] With

[0057] Or are the terms of the state representation; is the calculation period; is a delay; is the pressure of the anodic line; the vector concatenates the system inputs, namely the current the on / off purge control and the injection control, that is to say the number of injectors open in the first two configurations of stack 1 and in the stack purge configuration 1.

[0058] Note that when the purge command takes the value 1, stack 1 is then configured according to the third (purge) configuration shown above, in which both injection groups G1 and G2 are activated. Therefore, the number of open injectors is necessarily even and can take a value equal to the total number of injectors 2*N inj comprising these two groups G1,G2, in the chosen implementation mode.

[0059] The numerical parameters of the state equation (A, B and n d ) can be obtained by identification from pre-existing measurements, as is customary in the field. The delay n d , is typically between 0 and 4, and it can notably depend on the chosen sampling frequency (defining the calculation period T s ). The term A is equal to 1 or close to this value 1.

[0060] With this system model, the development of the injection control Cd can be formulated as an optimization problem for a predictive performance indicator, over a given prediction horizon defined by a number N of computation periods. This indicator can be based on the difference between a pressure estimated by the model over this horizon and the setpoint pressure P. ref The prediction horizon, N, is typically chosen between 2 and 20, for example, N=10, although other values ​​outside the range of 2 to 20 are also possible. Regardless of its form, this indicator provides a measure of the pressure deviation, relative to the setpoint pressure, that develops along the line over the given prediction horizon. A relatively small indicator reflects better adherence to the setpoint over the prediction horizon than a relatively large indicator.

[0061] As an illustration, this approach can be formulated by a constrained quadratic optimization equation, in which we find the difference between the pressure estimated at time i of the prediction horizon P(k+i) and the setpoint pressure P ref that we seek to minimize:

[0062]

[0063] Respecting the constraints:

[0064]

[0065] ,For ifCdp=0

[0066] For ifCdp= 1

[0067] ,For

[0068] Or is the prediction horizon; is the injection command profile, consisting of the N injection commands n inj (k+i) used successively in the equation of state at the end of each of the N periods of the prediction horizon matrices are respectively an output weighting matrix and a control input weighting matrix u. And are the upper and lower pressure limits to be respected.

[0069] This additional (and optional) constraint on the upper and lower pressure limits is advantageous because it prevents the anodic pressure of cell 1 from reaching, even transiently, values ​​incompatible with the proper functioning of this cell. The parameters And These can be parameterizable values, for example stored in a memory of the monitoring device S. Within the framework of the invention, any type of additional constraints may be added in addition to or in place of the one taken as an example, to take into account operational requirements.

[0070] The optimal solution to the constrained optimization problem described above is the profile injection commands applied to the prediction horizon N denoted by:

[0071]

[0072] Note that we generally have the delay n d well below the prediction horizon N. Therefore, the evaluation of the predictive performance indicator relies, through the pressure estimates P(k+i) provided by the equation of state, on the current value I(k+i) and the purge control Cdp(k+i) that make up the input vector u(k+i) of this equation. Some of these values ​​are not necessarily known at this instant k+i, particularly when this instant i is greater than the lag n dIn this case, the value of this current and the purge command can be set to their last known value in the input vector u(k-1). Regarding the purge command Cdp, it can be assumed that this value is known in advance by the monitoring device S, and that this device S makes the value of this purge command available to the control device K over the entire prediction horizon or over a portion thereof.

[0073] To obtain the optimal injection control profile , which defines the time series of injection commands to be applied successively during the prediction horizon, the control device K extracts the injection command to be applied to the injection group at the end of the current calculation period k. This injection command extracted from the optimal profile corresponds to the injection command Cd communicated by the control device K to the supervision device S, which applies it to one and / or the other of the injection blocks G1,G2, according to the configuration currently running of the stack, as previously presented.

[0074] The optimization problem formulated above is a constrained linear quadratic problem that can be solved using a dedicated optimization solver. However, this formulation and the requirement to use a dedicated solver impose a strong constraint on the performance of the control device K needed for its real-time implementation.

[0075] Due to the discrete nature of an injection command, chosen from the set {0,…,N inj}, the space of possible injection control profiles, over a prediction horizon N, is composed of N inj^N elements. Alternatively, instead of using a solver, one could explore the entire space of possible injection commands and search for the optimal injection command profile. Optimizing the predictive performance indicator within this space. However, this space is far too large to be fully explored within the available computation time. For example, for injection groups composed of 4 injectors (N inj taken equal to 4) and a time horizon of 10 calculation periods, there are more than 10^6 possible injection control profiles.

[0076] To facilitate the implementation of the algorithm on the control device K, and according to a very advantageous characteristic allowing for a reduction in computational load, the injection control profile is parameterized over the prediction horizon N. By parameterizing the injection control profile, we mean that the inputs of this profile, the injection commands on the prediction horizon, they are linked together. This parameterization leads to a reduction in the number of injection commands that it is possible to apply to each calculation period of the prediction horizon to a subset of injection commands, of reduced cardinality.

[0077] Therefore, the number of injection control profiles n inj The number of profiles to be evaluated during a calculation period is limited. inj is chosen to allow the implementation of the algorithm on the control device K, this number being able to be 100, 50, 10 or less depending on the characteristics of this device and, in particular, its computing capacity.

[0078] In a preferred embodiment, and to illustrate this approach, the parameterization is performed by setting the injection commands component of the injection control profile n injso that these commands are constant and equal to the value throughout the prediction horizon:

[0079]

[0080] In this embodiment, the number of possible injection control profiles n inj is limited to the number of injectors N inj of each injection group G1,G2. Given this limited number (the number N inj (typically on the order of 10 or less), it is possible to evaluate, during a calculation period, the predictive performance indicator for all possible injection control profiles n inj .

[0081] The injection control profile could, of course, be parameterized differently over the prediction horizon N than the one presented above as an illustration. More generally than simply parameterizing the inputs of an injection control profile, one can rely on any heuristic approach that leads to defining a limited and predetermined number of injection control profiles n. inj which will be evaluated during the optimization phase. This limited and predetermined number is strictly less than the total number of possible injection control profiles (the N inj (N possible profiles, mentioned above).

[0082] Advantageously, and to avoid the emergence of bias during regulation, the predictive performance indicator is adjusted by introducing a time weighting term. This weighting term tends to favor the early stages of the prediction horizon in the predictive performance indicator. Constraints can also be introduced into the performance indicator itself, which, according to the preferred implementation described above, allows the optimization problem of the predictive performance indicator to be expressed as follows:

[0083] Respecting the constraints:

[0084]

[0085] ,For ifCdp=0

[0086] For ifCdp= 1

[0087] where n is a priority coefficient of the temporal weighting factor ; is the constraint violation weighting matrix.

[0088] In this expression, the search for the optimal injection control profile is reduced to the search for a scalar quantity

[0089] Therefore, the optimization problem can be easily solved by applying the following calculation sequence: Apply each injection command profile n inj to the anodic line pressure model and calculate the predictive performance indicator associated with this injection control profile; select the injection control profile which optimizes the predictive performance indicator.

[0090] We can thus calculate the value of the indicator for each value of the injection control as a whole (( Or depending on the value of the Cdp purge command. We retain the value of the injection control which optimizes this indicator.

[0091] The Cd injection group command provided by the control device is extracted from the selected injection control profile In the preferred embodiment whereby an injection command profile consists of injection commands all equal to each other, this extraction step then consists of providing the scalar value .

[0092] Figures 3a and 3b compare, at two different operating points (corresponding to two different currents produced by the battery), the regulation of a battery according to the prior art and of a battery according to the invention.

[0093] The graphs represent the evolution of the pressure (in arbitrary units), as measured by the pressure sensor P, over a period of time (approximately 30 seconds on the graph of the, and 20 seconds on the graph of the).

[0094] Each of these graphs presents 3 time sections, 2 sections marked S1 during which the stack was operated using a control device configured according to the invention, and another section marked S2 during which this control device was configured according to a "bang bang" approach of the prior art.

[0095] We also marked the time periods (Cp=1) during which fuel cell 1 was configured in purge mode, with the purge valve open.

[0096] It is observed that in both operating points, the pressure excursion around the set pressure is much lower for the stack configured according to the invention, which shows the good performance of the regulation and the full benefit of the invention.

[0097] Of course the invention is not limited to the implementation methods described and alternative embodiments can be made without departing from the scope of the invention as defined by the claims.

[0098] Thus, the predictive pressure model used by the control device was chosen to linearly combine pressure and the input vector u, composed of the injection command, current, and purge command. Naturally, the predictive pressure model could be different from the example given. It could, in particular, use other measurements, such as a fuel cell temperature measurement or a measurement of the purge valve flow rate (or an estimate of this flow rate). This model could also be nonlinear or take the form of a system configured by machine learning (neural network, Bayesian network).

[0099] Similarly, the predictive performance indicator is not necessarily expressed in a quadratic form as previously presented. It can be expressed in any suitable form, based on the difference between the estimated pressure and the setpoint pressure over the prediction horizon.

[0100] Moreover, this setpoint pressure, provided by the monitoring device, is not necessarily constant.

[0101] It has been shown that the predictive performance indicator can incorporate constraints tending to maintain pressure between a minimum and maximum pressure, and it can be predicted that this indicator will incorporate other constraints (additional or as a replacement) or that it will not incorporate such constraints.

[0102] As previously mentioned, the control device can be applied to a fuel cell composed of several types of cells, each type associated with its own injection group as illustrated in this description, but this should not be considered a limitation. The control device can also be used in a fuel cell composed of cells of a single type, these cells being associated with a single injection group. This fuel cell may include a recirculation line for unburned fuel, although the invention is more particularly suited to a fuel cell without any recirculation between the purge valve and the anodic feed manifold.

Claims

Fuel cell (1) comprising a stack (E) of electrochemical cells (T1,T2) equipped with at least one anodic feed manifold (C1,C2) and at least one anodic discharge manifold (C3), the fuel cell (1) being intended to supply an electric current to a load and comprising: at least one anodic line passing through the stack (E) of electrochemical cells and in which a fuel fluid is capable of circulating, the anodic line extending: from an injection group (G1,G2) of a fuel fluid fluid fluid connected to the anodic feed manifold (C1,C2), the injection group (G1,G2) comprising a plurality of injectors selectively controllable in on / off mode, an injection group control being defined by the number of selectively controlled injectors open among the plurality of injectors. to a purge valve (Vp) controllable and fluidly connected to the anodic discharge manifold (C3);a pressure sensor (KP) capable of providing a representative value of the fuel fluid pressure in the anodic line; a control device (K) intended to develop, during successive calculation periods, the control of the injection group (Cd1,Cd2) to be applied at the end of the calculation period in question in order to regulate the fuel fluid pressure in the anodic line so that it conforms to a given setpoint pressure, the control device being configured to evaluate a predetermined number of injection control profiles, a profile being composed of the injection group controls over a determined prediction horizon, the control device also being configured to, during each calculation period: apply each injection control profile to a predictive model of anodic line pressure and calculate a predictive performance indicator associated with this injection control profile;Select the injection command profile that optimizes the predictive performance indicator; Extract from the selected injection command profile the injection group command (Cd) to be applied to the injection group (G1,G2) at the end of the calculation period. Fuel cell (1) according to the preceding claim in which the injection group controls composing an injection control profile are linked together. Fuel cell (1) according to the preceding claim in which the injection group commands composing an injection command profile are all equal to each other. Fuel cell (1) according to any one of the preceding claims wherein the predictive model of anodic line pressure links the anodic line pressure to the electric current, to a purge valve control and to the injection group control. Fuel cell (1) according to the preceding claim in which the predictive performance indicator incorporates constraints on the pressure of the anodic line, so that it tends to remain between a minimum pressure and a maximum pressure. Fuel cell (1) according to any one of the preceding claims wherein the predictive performance indicator includes a time weighting term. Fuel cell (1) according to any one of the preceding claims further comprising a supervisory unit (S) configured to control the purge valve (Vp) and apply the command (Cd) supplied by the control device (K) to the injection group (G1,G2). Fuel cell (1) according to the preceding claim comprising two injection groups (G1,G2) respectively associated with two anodic feed collectors (C1,C2) of the stack (E) of electrochemical cells, defining two anodic lines extending to the purge valve (Vp), the supervisory unit (S) being configured to apply the injection group control (Cd) supplied by the control device (K) to one and / or the other of the two injection groups. Fuel cell (1) according to the preceding claim in which the two injection groups (G1,G2) have the same number of injectors. Fuel cell (1) according to the preceding claim in which the injectors of one injection group (G1,G2) have the same characteristics as the injectors of the other injection group. Fuel cell (1) according to any one of the preceding claims wherein the pressure sensor (KP) is disposed at the level of the anodic discharge manifold (C3). Fuel cell (1) according to any one of the preceding claims wherein the fuel cell (1) is of the proton exchange membrane type. Fuel cell (1) according to any one of the preceding claims devoid of any recirculation between the purge valve and the anodic feed manifold.

Images