Control of an operating fluid supply flow for branching sections of a flow path of a fuel cell system

Abstract

The present invention relates to a method for controlling an operating fluid supply flow for supplying branching sections (211, 212, 213, 214) of a flow path (210) of a fuel cell system (300) with an operating fluid, which can be provided to the flow path (210) by an operating fluid conveying device (220) with an actual supply flow (IVS). First, the degrees of passage of control elements (230) are detected, the control elements being arranged downstream of the operating fluid conveying device (220) in the branching sections (211, 212, 213, 214) and the degree of passage of each of the control elements being controllable in order to individually set an actual branch supply flow (IZVS) in the respective branching section (211, 212, 213, 214). On the basis of at least one of the detected degrees of passage, a target supply flow (SVS) with which the operating fluid is to be provided to the branching sections (211, 212, 213, 214) by the operating fluid conveying device (220) is determined. The actual supply flow (IVS) is then controlled to the target supply flow (SVS). The invention further relates to a computer program product, a control device (100), a control system (200) and a fuel cell system (300), each of which make use of the method according to the invention.

Description

[0001] Control of an operating fluid supply flow for branching sections of a flow path of a fuel cell system

[0002] The invention relates to a method, a device, and systems for controlling an operating fluid supply flow for supplying branching sections of a flow path of a fuel cell system with operating fluid. The invention further relates to a computer program product for the computer-based execution of such a method.

[0003] Reactants for fuel cell operation are typically provided at a specific temperature, pressure, and quantity. To adjust these process parameters accordingly, fuel cell systems often have branched pipelines leading to the fuel cells, along which the reactants undergo chemical and thermal processes.

[0004] The reactants must also be continuously supplied in sufficient quantities, since fuel cells are primarily operated continuously. To adjust the amount of reactant supplied to the fuel cells, the reactant supply source is often regulated, thus adjusting the mass flow through the lines. For example, oxygen is used as a reactant in fuel cells, which is supplied as an air stream from a blower to an air-side line system of the fuel cell system.

[0005] It is known from the prior art to regulate the total air mass flow supplied during operation. For example, a target total air mass flow is first calculated from a specified air requirement of the fuel cell. Based on this calculated target total air mass flow, a target speed for the fan is then determined and adjusted accordingly. Control of the total air mass flow is then enabled by comparing the target total air mass flow with the actual total air mass flow measured by a flow sensor.

[0006] The disadvantage of this approach is that, under certain circumstances, a temporary lack of air can occur in the fuel cells. Such circumstances include, for example, singular and / or dynamic events in the fuel cell system, or certain operating modes. In each of these cases, the initial calculation of the target total air mass flow does not take such occurrences into account, or only inadequately does so. A suddenly changed demand for atmospheric oxygen is therefore difficult to detect and control using the conventional approach. Control via the total air mass flow is also prone to errors, since flow sensors provide inaccurate data on the actual total air mass flow in the event of disturbances such as turbulence. Such problems can of course also occur with gaseous media other than air that are used as reactants, such as hydrogen or carbon dioxide.

[0007] Accordingly, with the procedure known from the state of the art, there is an increased risk that fuel cells or at least parts of the piping system are insufficiently supplied with reactants.

[0008] It is therefore an object of the present invention to at least partially remedy the disadvantages described above. In particular, the object of the present invention is to quickly, robustly, and demand-oriented control of the total mass flow of reactant to be provided in a fuel cell system, while at the same time being able to dispense with data from a flow sensor for the total mass flow.

[0009] The above object is achieved by a method having the features of claim 1, a computer program product having the features of claim 11, a control device having the features of claim 12, a control system having the features of claim 13 and a fuel cell system having the features of claim 15.

[0010] Further advantages and features of the invention emerge from the dependent claims, the description and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the computer program product according to the invention, the control device according to the invention, the control system according to the invention and the fuel cell system according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is and can always be made to each other. A first aspect of the invention relates to a method for controlling an operating fluid supply flow for supplying branching sections of a flow path of a fuel cell system with an operating fluid. The operating fluid can be provided to the flow path by an operating fluid conveying device with an actual supply flow.

[0011] In the method, a flow rate of at least one actuator is detected. The actuator is arranged downstream of the operating fluid delivery device in one, in particular in each, of the branching sections. The actuator is further controllable with regard to its flow rate in order to control an actual branch supply flow through the branching section according to a desired branch supply flow.

[0012] In the method, a target supply flow is determined. The operating fluid is to be supplied to the branching sections using the target supply flow. The target supply flow is determined based on the detected flow rate of the at least one actuator.

[0013] In the method, the actual supply flow is controlled. The actual supply flow from the operating fluid delivery device is to be provided to the branching sections as the operating fluid supply flow. The actual supply flow is controlled to the determined target supply flow.

[0014] In other words, a method is provided in which an operating fluid supply flow, from which branch sections of a flow path are supplied with operating fluid, is controlled on the basis of passivations of at least one actuator arranged in one of the branch sections.

[0015] According to the invention, a control method is therefore provided.

[0016] In the context of the invention, “controlling” can be understood in particular as controlling and / or regulating.

[0017] In this process, an operating fluid supply flow is controlled.

[0018] In the context of the invention, a "flow" can be understood in particular as the flow of a substance. Preferably, the flow can be defined by the amount of substance passing through a cross-sectional area per unit time. For example, the flow can be defined as a mass flow (e.g., kg / s) and / or volume flow (e.g., ml / s) through a line or channel. The terms "flow," "flow rate," or "flow rate" are often used synonymously to characterize a flow.

[0019] The operating fluid supply flow is intended for supplying branching sections of a flow path of a fuel cell system with an operating fluid.

[0020] Within the scope of the invention, the term “supply” can be understood in particular as providing and / or supplying. An “operating fluid” can be understood in particular as a fluid or a gaseous substance. The substance can preferably be at least partially gaseous during use in operation. Furthermore, the substance can preferably be used in the operation or for the operation of a fuel cell system. The operating fluid can, for example, be a reactant such as air or fuel. A “branching section” can, for example, be understood as a line section that branches off from a main line carrying the operating fluid at a point that is downstream of the inlet with respect to the flow direction of the operating fluid, and that provides at least one alternative flow path in the main line.Within the scope of the invention, the term "flow path" can be understood in particular as the totality of possible flow paths for the operating fluid, such as a conduit system. Furthermore, the flow path can preferably be, for example, a fluidic connection between a flow source, such as an air blower, and at least one flow sink, such as the air side of a fuel cell, for the operating fluid, such as air.

[0021] The operating fluid can be provided to the flow path by an operating fluid conveying device with an actual supply flow.

[0022] Within the scope of the invention, an "operating fluid delivery device" can be understood, in particular, as a device for providing operating fluid as a flow. For example, the operating fluid delivery device can be a blower, a pump, and / or a pressurized tank, and preferably comprise several of these components. According to the invention, a flow rate of at least one actuator is detected.

[0023] Within the scope of the invention, a "permeability" can be understood, for example, as the extent of permeability of an actuator to the operating fluid. Thus, the permeability can, for example, indicate a flow rate, a flow area, or a valve opening. Preferably, the permeability can be specified as a relative value in relation to a state of unrestricted flow, for example, as a percentage. The actuator can, for example, be a valve or a throttle. "Detecting" within the scope of the invention can be understood, in particular, as measuring, recording, and / or recording.

[0024] The actuator, the degree of which is detected, is arranged downstream of the operating fluid conveying device in one of the branching sections and is controllable with regard to its degree of which is controlled in order to control an actual branch supply flow through the branching section in accordance with a desired branch supply flow.

[0025] Within the scope of the invention, the controllability of the actuator with respect to its transmittance can be understood in particular in such a way that, for example, the transmittance of the actuator can be variably adjusted within a range between a fully open and fully closed state. This allows the actuator to be variably controlled with respect to its transmittance. A purely binary transmittance control can also be encompassed by the invention. With binary control of the transmittance, for example, the actuator has only two opening states: an open and a closed state.

[0026] A target supply flow at which the operating fluid is to be supplied to the branching sections is determined based on the detected flow rate of the at least one actuator. The actual supply flow to be supplied by the operating fluid delivery device to the branching sections as the operating fluid supply flow is controlled to the determined target supply flow.

[0027] Within the scope of the invention, "controlling to a target value" can be understood in particular as approaching the target value from below and / or above. Thus, the operating fluid supply flow can be controlled independently of a measured operating fluid supply flow, making it unnecessary to provide corresponding flow sensors. Furthermore, it is possible to react quickly and in a demand-oriented manner to sudden changes in the fuel cell system. For example, the method can detect an increased demand for operating fluid in one of the branching sections if the associated actuator requires a relatively high flow rate to provide a sufficient supply. Accordingly, the detected information on the flow rate can be used to determine when the operating fluid supply flow needs to be changed, for example to meet an increased demand for operating fluid.The flow rates of the actuators can thus serve as an indicator for the operating fluid demand, eliminating the need to determine a change in demand by comparing the target and actual values ​​for the total mass flow of the operating fluid. Furthermore, the control of the operating fluid supply flow can be performed stably, as it is changed by adjusting the amount of operating fluid provided by the operating fluid delivery device, rather than by the actuators, which only influence their respective branch supply flow.

[0028] According to a preferred embodiment, the detected transmittance can comprise an actual transmittance of the at least one actuator. Alternatively or additionally, the detected transmittance can comprise a desired transmittance of the at least one actuator.

[0029] This allows for application-oriented determination of the target operating fluid supply flow, improving control of the operating fluid supply flow. For example, if the determination of the target operating fluid supply flow is based on a current actual flow rate, the control of the operating fluid supply flow can be based on an assessment of the actual situation of a branching path. However, if the determination of the target operating fluid supply flow is based on a target flow rate, the control of the operating fluid supply flow can be based on an assessment of a desired situation for the branching path. A further advantage is that, for example, only binary switchable actuators can be used, since the target operating fluid supply flow can be determined from a calculated flow rate.If the determination of the target operating fluid supply flow is based on both the actual flow rate and the target flow rate, a changing demand for operating fluid can be recorded precisely and quickly using a target-actual comparison, since even minor changes can be detected.

[0030] According to a further preferred embodiment, the actual branch supply flow of the operating fluid can be detected through a branching section. A flow sensor for detection can preferably be arranged in the branching section. A target flow rate for the at least one actuator can be determined based on the detected actual branch supply flow and a preferably predetermined target branch supply flow. At least the determined target flow rate of the at least one actuator can preferably be detected as the detected flow rate.

[0031] In this way, the actual supply flow can be controlled based on the actual operating fluid demand for a branch section. It is also possible to control the operating fluid flow through the individual branch section without controlling the flow rate of the actuator itself.

[0032] According to a preferred embodiment, the determined target transmittance can be compared with a transmittance limit range. The transmittance limit range can preferably have an upper transmittance limit and / or a lower transmittance limit. A limit of the transmittance limit range, i.e. preferably the upper transmittance limit or the lower transmittance limit, can be defined as the target transmittance to limit the actual transmittance if the determined target transmittance is outside the transmittance limit. The upper transmittance limit can preferably be at least 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the maximum transmittance of the actuator. Alternatively or additionally, the lower transmittance limit may be at least 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40% of the maximum transmittance of the actuator.

[0033] This ensures that all branch sections are supplied with operating fluid. Limiting the flow rate also allows for better control of the branch supply flow, as the actuator still has room for adjustment movements to change the flow rate. This means that the actuator's end positions (fully open or closed) are not easily reached and can therefore be used for control in rapidly changing or critical conditions in the fuel cell system.

[0034] Preferably, the target supply flow can be determined on the basis of the determined target transmittance and not on the basis of the limited transmittance.

[0035] In this way, the stability of the supply flow control can be improved, since the actuators are not controlled arbitrarily, but within a limit range and, independently of this, a changed demand for operating fluid can be taken into account when determining the target supply flow with its actual size.

[0036] According to a further preferred embodiment, the target supply flow can be determined using a control function. Preferably, the control function can have at least the detected permeability as an input parameter. The control function can, for example, have a linear, polynomial, logarithmic, and / or exponential function.

[0037] Thus, the target supply flow can be determined precisely and flexibly using functional equations, since the control function can mathematically simulate processes or transfer functions of certain parameters.

[0038] According to a preferred embodiment, it is also conceivable to detect the permeability of more than one actuator. In particular, detecting the permeability may involve detecting the permeability of at least two actuators, wherein the actuators are arranged downstream of the operating fluid delivery device in mutually different branching sections of the flow path and are each controllable with respect to their permeability.

[0039] Thus, each branching section can be included, for example, in the determination of the target supply flow.

[0040] Preferably, determining the target supply flow may involve determining a maximum from preferably all detected flow rates. Preferably, the maximum may be determined from the actual flow rates or target flow rates detected for each of the control elements. The maximum thus determined may be set as the flow rate used to determine the target supply flow.

[0041] Alternatively or additionally, the detected flow rate can comprise an actual flow rate and a target flow rate for each of the at least two actuators. Determining the target supply flow can comprise determining the maximum of the detected actual flow rates for each actuator and determining the maximum of the detected target flow rates for each actuator. Preferably, the maxima thus determined can be defined as the flow rate used to determine the target supply flow. The target supply flow can preferably be determined using a control function that has at least the two determined maxima as input parameters.

[0042] Alternatively or additionally, according to a further preferred embodiment, it is also conceivable to determine the target supply flow based on a flow ratio between an actual flow rate and a target flow rate of the at least one actuator. For this purpose, the detected flow rate can have an actual flow rate and a target flow rate for at least one actuator. To determine the target supply flow, a flow ratio between the actual flow rate and the target flow rate can be determined. Preferably, the flow ratio can be formed from the actual flow rate and the target flow rate of the same actuator or different actuators. The determined flow ratio can be compared with a flow ratio limit value. The target supply flow can be determined according to a control function which has at least the determined flow rate as an input parameter.Preferably, the actual supply flow can be controlled relative to the desired supply flow until the flow ratio no longer exceeds the flow ratio limit value.

[0043] Using the aforementioned determination methods, it is advantageously easy to identify whether there is a changed demand for operating fluid for the flow path. Based on this, the target supply flow can be determined accordingly at a suitable level. According to a preferred embodiment, monitoring the actual supply flow can involve converting the determined target supply flow into a control signal KS. The control signal can preferably correspond to a target control parameter of the operating fluid delivery device. For example, the target control parameter can preferably comprise a target delivery speed, a target delivery pressure, an electrical input current, and / or an electrical input voltage. The operating fluid delivery device can be operated with the target control parameter in response to the control signal.

[0044] Alternatively or additionally, controlling the actual supply flow may comprise adjusting a flow rate of an operating fluid flow by means of a control section of the operating fluid delivery device, wherein the control section is arranged to discharge the operating fluid at the actual supply flow. The flow rate can preferably be adjusted by adjusting an opening cross-section of the control section.

[0045] Within the scope of the invention, a "control signal" can be understood as transmittable information with adaptable content that enables control of an actuator. For example, the control signal can be a control signal or control command.

[0046] In this way, the control of the actual supply flow can be achieved with simple technical means and can be carried out efficiently and accurately.

[0047] A further aspect of the invention relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method described above.

[0048] A further aspect of the invention relates to a control device for controlling an operating fluid supply flow for supplying branching sections of a flow path of a fuel cell system with an operating fluid that can be provided to the flow path by an operating fluid delivery device with an actual supply flow. For this purpose, the control device has a detection module for detecting a flow rate of at least one actuator, which is arranged downstream of the operating fluid delivery device in one of the branching sections and whose flow rate can be controlled. The control device further has a determination module for determining a target supply flow with which the operating fluid is to be provided to the branching sections. The determination module is designed to determine the target supply flow based on the detected flow rate of the at least one actuator.The control device comprises a control module configured to output a control signal to control the actual supply flow as the operating fluid supply flow to the determined target supply flow.

[0049] A further aspect of the invention relates to a control system for controlling an operating fluid supply flow for supplying branching sections of a flow path of a fuel cell system with an operating fluid. The control system comprises an operating fluid delivery device for providing the operating fluid to the flow path with an actual supply flow. Furthermore, the control system comprises at least one actuator, which is arranged downstream of the operating fluid delivery device in one of the branching sections and whose permeability is controllable in order to control an actual branch supply flow through the branching section in accordance with a desired branch supply flow. The control system further comprises the aforementioned control device, which is coupled to the operating fluid delivery device and the at least one actuator.

[0050] The coupling with the control device can preferably be mechanical, signaling and / or functional.

[0051] According to a preferred embodiment, the actuator can be, for example, a controllable valve. The flow path can, for example, have a plurality of branching sections that are fluidically parallel to one another. At least one actuator can preferably be provided in each or all of the branching sections. Furthermore, preferably, for example, at least one of the branching sections can have at least one flow sensor arranged upstream of the actuator for detecting the actual branch supply flow of the operating fluid through the associated branching section. Preferably, the flow path can, for example, be at least a section of an air supply path that extends to an air side of a fuel cell stack. Furthermore, preferably, the operating fluid can, for example, comprise ambient air. The operating fluid conveying device can, for example, be a controllable air blower.

[0052] In the context of the invention, a “flow sensor” can be understood in particular as an instrument for detecting a mass or volume flow.

[0053] A further aspect of the invention relates to a fuel cell system. The fuel cell system can preferably be a PEM, SOFC, or SOEC fuel cell system. The fuel cell system has at least one fuel cell stack with an air side and a fuel side. Furthermore, the fuel cell system has at least one flow path with branching sections. An inflow of operating fluid for operating the fuel cell stack is provided through the flow path of the air side or the fuel side. The fuel cell system further has the aforementioned control system. The control system is arranged in the fuel cell system to control an operating fluid supply flow in order to supply the branching sections with operating fluid.

[0054] With the aforementioned further aspects of the invention and their further developments, the same advantages and technical effects can be achieved that have already been described in detail above for the method according to the invention. Therefore, an explicit repetition of these will be omitted here.

[0055] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. They show schematically:

[0056] Fig. 1 shows an embodiment of a control device, control system and fuel cell system according to the invention,

[0057] Fig. 2 shows a further embodiment of a control device according to the invention and an embodiment of a method according to the invention, and

[0058] Fig. 3 shows another embodiment of a control system and fuel cell system according to the invention. Figures 1 to 3 show different aspects and embodiments of the invention.

[0059] Figures 1 and 3 show, for example, a control system 200 according to the invention in a fuel cell system 300. The control system 200 is provided for controlling a flow of an operating fluid to branching sections 211, 212, 213, 214 of a flow path 210. Since the operating fluid flow supplies the branching sections 211, 212, 213, 214 with operating fluid, this flow is referred to as the operating fluid supply flow. In Figure 1, the flow path 210 is illustrated by way of example with three branching sections 211, 212, 213, and a further branching section 214 is indicated. Of course, the flow path 210 can also have only two or more than the four branching sections 211, 212, 213, 214 shown.

[0060] Figures 1 and 3 illustrate the operation of the control system 200 based on a configuration of the flow path 210 as an air path of the fuel cell system 300. In Figure 1, air, as the operating fluid, flows into the flow path 210 via an air inlet 201. The flow path 210 can, for example, be a conduit system. A conduit section can extend from the air inlet 201 to a branching point 219, from which several conduits extend as the branching sections 211, 212, 213, 214, each forming separate flow paths for the operating fluid.

[0061] For the defined provision of the operating fluid supply flow, the control system 200 has an operating fluid delivery device 220, from which the operating fluid is delivered to the line path 210 at an actual supply flow IVS. In Figures 1 and 3, the operating fluid delivery device 220 is illustrated, by way of example, as an air blower. The operating fluid delivery device 220 is preferably controllable, in particular with regard to the available operating fluid supply flow.

[0062] The branching sections 211, 212, 213 preferably each have an actuator 230. The actuators 230 can be controlled with regard to their flow rate. For example, the actuator 230 can be designed to carry out control movements, for example, to enable the detection and output of its currently set actual flow rate IDG. Furthermore, the actuator 230 can adjust the flow rate to a target flow rate SDG, preferably based on an adjustment specification. Thus, an operating fluid flow through the respective branching section 211, 212, 213 can be controlled. This is illustrated in Figure 1 by the indication of actual branch supply flows IZVS, which can be detected, for example, by flow sensors 240. The flow sensors 240 can be arranged between the operating fluid conveying device 220 and the respective actuator 230. The actuators 230 may preferably be control valves.

[0063] The control system 200 further comprises a control device 100, which is coupled to the operating fluid delivery device 220 and the at least one actuator 230. In Figures 1 and 3, the coupling is indicated, for example, by signal connections, which can be provided wirelessly or wired, for example. In particular, the coupling can enable an exchange of information between the components of the control system 200 and the control device 100. The control device 100 is also an independent component of the invention, but will be explained in more detail below in the context of the fuel cell system 300 and the control system 200 for clarity.

[0064] The control device 100 can be configured, for example, as a process controller or computer capable of executing a computer program. The control device 100 has a detection module 101 with which the actual transmittances IDG of the actuators 230 can be detected. For this purpose, as shown in Figures 1 and 3, measurement signal lines can connect the control device 100 to the actuators 230. The detection module 101 can be configured, for example, as a data interface.

[0065] Furthermore, the control device 100 has a determination module 102 for determining a target supply flow SVS, i.e., in particular, for determining a desired value for the flow of operating fluid in the section of the flow path 210 between the operating fluid conveying device 220 and the branching sections 211, 212, 213, 214. The determination module 102 is configured to determine the target supply flow SVS based on the detected flow rate of the actuators 230.

[0066] Furthermore, the control device 100 has a control module 103, by means of which a control signal KS is output to control the actual supply flow IVS. This is illustrated by way of example in Figures 1 and 3 by a signal line from the control device 100 to the operating fluid delivery device 220. The control module 103 can, for example, be a signal output of the control device 100.

[0067] Figure 2 shows a preferred embodiment of the control device 100 and, in particular, the determination of the desired supply flow SVS. Figure 2 can also serve to explain the method according to the invention for controlling the operating fluid supply flow.

[0068] First, the transmittance of at least one of the actuators 230 is recorded. This can be the actual transmittance IDG and / or the target transmittance SDG. Since the transmittances of several actuators 230 are recorded in the example in Figure 2, the actual transmittances IDG and target transmittances SDG are shown as vectors "«..."".

[0069] The target transmittances SDG can either be user-defined or determined. For example, a target transmittance determination module 105 can be provided in the control device 100 to determine the target transmittance SDG. In addition to the actual transmittances IDG, the actual branch supply flows IZVS of the branch sections 211, 212, 213 can also preferably be recorded. In the control device 100, this can be made possible, for example, by means of the previously described recording module 101. Based on a comparison of these with predetermined target branch supply flows SZVS, the target transmittances SDG for the respective actuators 230 can then be determined. For this purpose, a target transmittance determination module 1051 can be provided in the control device 100. The target branch supply flows SZVS can be calculated, for example, based on the desired operation of the fuel cells.

[0070] In order to prevent a sufficient supply to all branching sections 211, 212, 213, 214 from being jeopardized if the target transmittances SDG determined in this way were to be transmitted directly to the control elements 230 for flow control in the branches without further control, the determined target transmittances SDG can also be restricted to suitable limits. For this purpose, a target transmittance restriction module 1052 can be provided, for example, in the control device 100. There, the determined target transmittance SDG can be compared with a transmittance limit range, which can have an upper transmittance limit OG and a lower transmittance limit UG. If one or more of the determined target transmittances SDG lie outside the transmittance limit range, the upper transmittance limit OG or lower transmittance limit UG can be set for such transmittances.The target transmittances modified in this way can be output to the actuators 230 as limited target transmittances bSDG.

[0071] It should also be noted that, preferably during operation, the control elements 230 can be controlled based on the target flow rates SDG or bSDG. Alternatively, it is also conceivable for the control elements 230 to remain in the same opening position, so that the actual branch supply flows IZVS are controlled either solely by the operating fluid delivery device 220 or additionally in combination with the control elements 230.

[0072] The target supply flow SVS is determined based on the measured flow rates of the actuators 230. In addition to the actual flow rates IDG, this can also include the target flow rates or the limited target flow rates bSDG. In Figure 2, in addition to the actual flow rates IDG, the determined target flow rates SDG are preferably also used to determine the target supply flow SVS. From these flow rates, a maximum for the actual flow rates IDG and a maximum for the target flow rates SDG are then determined (indicated by MAX functions) and passed to a control function KF to calculate the target supply flow SVS. The control function KF can preferably be a lookup table, a fuzzy controller, or a neural network. In the control device 100, the aforementioned method steps can be implemented, for example, by the determination module 102.

[0073] Using the determined target supply flow SVS, the actual supply flow IVS can be controlled relative to the determined target supply flow SVS. For example, the controllable operating fluid conveying device 220 can be controlled based on the target supply flow SVS. For this purpose, the determined target supply flow SVS can preferably be converted into a control signal KS in the control module 103 of the control device 100. The control signal KS can, for example, be such that it corresponds to a target control parameter of the operating fluid conveying device 220. Examples of the target control parameter can be a target conveying speed or air blower speed. The operating fluid conveying device 220 can detect the control signal KS and, in response, operate with the target control parameter.

[0074] From the description of the control method according to the invention and the associated figures, it will also become clear to the person skilled in the art how an associated computer program product is to be designed, and this will therefore not be discussed further below.

[0075] Figure 3 shows a highly simplified representation of the fuel cell system 300, in which not all components and operating components are shown. The fuel cell system 300 can be a PEM or SOEC fuel cell system. The fuel cell system 300 has at least one fuel cell stack 301 with an air side 310 and a fuel side 320. Furthermore, the fuel cell system 300 has the flow path 210, through which an inflow of operating fluid is provided to the air side 310 or the fuel side 320 for the operation of the fuel cell stack 301. In Figure 3, the flow path 210 is shown as leading to the air side 310 by way of example. In addition, the control system 200 is provided in the fuel cell system 300 to control the operating fluid supply flow for supplying the branching sections 211, 212, 213, 214 with the operating fluid.

[0076] In Figure 3, ambient air flows through an air filter 361 into the air path 210, drawn by the suction of the air blower 220. This air path 210 has four branching sections 211, 212, 213, 214, some of which have heat exchangers or heaters to heat the air. The branching sections 211, 212, 213, 214 are merged before reaching an air inlet 311 of the air side 310. The used air is expelled from the fuel cell stack 301 via an air exhaust outlet 312.

[0077] Likewise, in the example of Figure 3, fuel is first filtered through a fuel filter 362 before entering a fuel path 340. A recirculation blower 363 is also used. The fuel path 340 branches downstream of the recirculation blower 363, as exemplified by fuel branch sections 341, 342. Here, at least one of the fuel branch sections 341, 342 can have an actuator 230. The fuel is supplied to the fuel cells 301 via a fuel inlet 321, and the spent fuel is removed from them via a fuel exhaust outlet 322. It is conceivable that the method according to the invention, the control device 100, and the control system 200 could also be used to control a fuel supply to the fuel branch sections 341, 342.

[0078] The above explanation of the embodiments describes the present invention exclusively by way of examples.

[0079] List of reference symbols

[0080] 100 control device

[0081] 101 Recording module

[0082] 102 Investigation module

[0083] 103 Control module

[0084] 105 Target transmittance determination module

[0085] 1051 Target transmittance determination module

[0086] 1052 Target transmittance restriction module

[0087] 200 control system

[0088] 201 Air intake

[0089] 210 Flow path

[0090] 211 , 212, 213, 214 branching section(s)

[0091] 219 branching point

[0092] 220 Operating fluid conveying device

[0093] 230 actuator

[0094] 240 flow sensor

[0095] 300 fuel cell system

[0096] 301 fuel cell stacks

[0097] 310 Airside

[0098] 311 Air inlet

[0099] 312 Air exhaust outlet

[0100] 320 Fuel side

[0101] 321 Fuel inlet

[0102] 322 Fuel exhaust outlet

[0103] 340 Fuel path

[0104] 341 , 342 Fuel branch sections

[0105] 361 air filter

[0106] 362 fuel filter

[0107] 363 blowers

[0108] KF control function

[0109] OG upper limit of transmittance

[0110] UG lower limit of transmittance

[0111] IVS actual supply flow

[0112] IZVS Actual branch supply flow IDG Actual flow rate

[0113] SDG target transmittance bSDG limited target transmittance

[0114] SZVS target branch supply flow

[0115] SVS target supply flow

[0116] KS control signal

Claims

Patent claims 1. A method for controlling an operating fluid supply flow for supplying branching sections (211, 212, 213, 214) of a flow path (210) of a fuel cell system (300) with an operating fluid which can be provided to the flow path (210) by an operating fluid conveying device (220) with an actual supply flow (IVS), wherein the following steps are provided: - detecting a degree of passage of at least one actuator (230) which is arranged downstream of the operating fluid conveying device (220) in one of the branching sections (211, 212, 213, 214) and which is controllable with regard to its degree of passage in order to control an actual branch supply flow (IZVS) through the branching section (211, 212, 213, 214) in accordance with a desired branch supply flow (SZVS); - determining a desired supply flow (SVS) with which the operating fluid is to be provided to the branching sections (211, 212, 213, 214) based on the detected degree of passage of the at least one actuator (230); and - Controlling the actual supply flow (IVS), which is to be provided by the operating fluid conveying device (220) to the branching sections (211, 212, 213, 214) as the operating fluid supply flow, to the determined target supply flow (SVS).

2. Method according to claim 1, characterized in that the detected transmittance comprises an actual transmittance (IDG) and / or a desired transmittance (SDG) of the at least one actuator (230).

3. A method according to claim 1 or claim 2, characterized by - detecting the actual branch supply flow (IZVS) of the operating fluid through the associated branch section (211, 212, 213, 214); and - determining a desired flow rate (SDG) for the at least one actuator (230) based on the detected actual branch supply flow (IZVS) and on the desired branch supply flow (SZVS), wherein at least the determined target transmittance (SDG) of the at least one actuator (230) is detected as the detected transmittance.

4. Method according to claim 3, characterized by - comparing the determined target transmittance (SDG) with a transmittance limit range, preferably comprising an upper transmittance limit (OG) and / or a lower transmittance limit (UG); and - Setting a limit (UG, OG) of the transmittance limit range as the target transmittance (SDG) for limiting the actual transmittance (IDG) if the determined target transmittance (SDG) is outside the transmittance limit range, wherein the upper transmittance limit (OG) is preferably at least 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of the maximum transmittance of the actuator (230), and / or wherein the lower transmittance limit (UG) is preferably at least 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40% of the maximum transmittance of the actuator (230).

5. Method according to one of claims 2 to 5, characterized in that the desired supply flow (SVS) is determined on the basis of the determined desired transmission rate (SDG).

6. Method according to one of the preceding claims, characterized in that the desired supply flow (SVS) is determined by means of a control function (KF) which has at least the detected transmittance as an input parameter, wherein the control function (KF) preferably has a linear, polynomial, logarithmic and / or exponential function.

7. Method according to one of the preceding claims, characterized in that the detection of the degree of permeability comprises detecting the degrees of permeability of at least two of the actuators (230) which are arranged downstream of the operating fluid conveying device (220) in different and preferably fluidically parallel branching sections (211, 212, 213, 214) of the flow path (210) and each are controllable with regard to their permeability; and determining the desired supply flow (SVS) further comprises: - determining the maximum from preferably all of the detected transmittances of the actuators (230), preferably the maximum from the actual transmittances (IDG) or target transmittances (SDG) detected for each of the actuators (230), and - Specify the determined maximum as the transmittance used to determine the desired supply flow (SVS).

8. The method according to claim 7, characterized in that the detected flow rate comprises an actual flow rate (IDG) and a desired flow rate (SDG) to each of at least two of the actuators (230), and determining the desired supply flow (SVS) further comprises: - Determining the maximum of the recorded actual transmittances (IDG) of each actuator (230); - determining the maximum of the recorded target transmittances (SDG) of each actuator (230); and - Determining the desired supply flow (SVS) according to a control function (KF) which has at least the two determined maxima as input parameters.

9. Method according to one of the preceding claims, characterized in that the detected flow rate comprises an actual flow rate (IDG) and a desired flow rate (SDG) to at least one actuator (230), and the determination of the desired supply flow (SVS) further comprises: - Determining a transmission ratio between the actual transmission rate (IDG) and the desired transmission rate (SDG), wherein the transmission ratio is preferably formed from the actual transmission rate (IDG) and the desired transmission rate (SDG) of the same actuator (230) or different actuators (230), - comparing the determined transmission ratio with a transmission ratio limit value, and - Determining the desired supply flow (SVS) according to a control function (KF) which has at least the determined flow ratio as an input parameter; and preferably, the actual supply flow (IVS) is controlled relative to the desired supply flow (SVS) until the flow ratio no longer exceeds the flow ratio limit value.

10. Method according to one of the preceding claims, characterized in that the control of the actual supply flow (IVS) comprises: - converting the determined target supply flow (SVS) into a control signal (KS) which corresponds to at least one target control parameter of the operating fluid delivery device (220), wherein the target control parameter preferably comprises a target delivery speed, a target delivery pressure, an electrical input current, and / or an electrical input voltage; and - Operating the operating fluid conveying device (220) with the desired control parameter in response to the control signal (KS).

11. A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out a method according to any one of the preceding claims 1 to 10.

12. Control device (100) for controlling an operating fluid supply flow for supplying branching sections (211, 212, 213, 214) of a flow path (210) of a fuel cell system (300) with an operating fluid, which can be provided to the flow path (210) by an operating fluid conveying device (220) with an actual supply flow (IVS), characterized by - a detection module (101) for detecting a degree of permeability of at least one actuator (230), which is arranged downstream of the operating fluid conveying device (220) in one of the branching sections (211, 212, 213, 214) and which is controllable with regard to its degree of permeability; - a determination module (102) for determining a target supply flow (SVS) with which the operating fluid is supplied to the branching sections (211, 212, 213, 214), wherein the determination module (102) is designed to determine the target supply flow (SVS) based on the detected flow rate (IDG, SDG) of the at least one actuator (230); and - a control module (103) for outputting a control signal (KS), wherein the control module (103) is designed to control the actual supply flow (IVS) as the operating fluid supply flow to the determined target supply flow (SVS).

13. Control system (200) for controlling an operating fluid supply flow for supplying branching sections (211, 212, 213, 214) of a flow path (210) of a fuel cell system (300) with an operating fluid, comprising - an operating fluid conveying device (220) for providing the operating fluid to the flow path (210) with an actual supply flow (IVS); - at least one actuator (230) which is arranged downstream of the operating fluid conveying device (220) in one of the branching sections (211, 212, 213, 214) and which is controllable with regard to its degree of permeability in order to control an actual branch supply flow (IZVS) through the branching section (211, 212, 213, 214) in accordance with a desired branch supply flow (SZVS); characterized by - a control device (100) according to claim 12, which is coupled to the operating fluid conveying device (220) and the at least one actuator (230).

14. Control system (200) according to claim 13, characterized in that - the actuator (230) is a controllable valve; - the flow path (210) has a plurality of fluidically parallel branching sections (211, 212, 213, 214), in each of which at least one actuator (230) is provided; - at least one of the branching sections (211, 212, 213, 214) has at least one valve arranged upstream of the actuator (230) Flow sensor (240) for detecting the actual branch supply flow (IZVS) of the operating fluid through the associated branch section; - the operating fluid contains ambient air; and / or - the operating fluid conveying device (220) is a controllable air blower.

15. Fuel cell system (300), comprising - at least one fuel cell stack (301) with an air side (310) and a fuel side (320), and - a flow path (210) with branching sections (211, 212, 213, 214) through which an inflow of operating fluid for the operation of the fuel cell stack (301) is provided to the air side (310) or the fuel side (320), characterized by - a control system (200) according to claim 13 or claim 14, which is arranged in the fuel cell system (300) to control an operating fluid supply flow for supplying the branching sections (211, 212, 213, 214) with the operating fluid.

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