DE102014224380A1 - Method for the predictive operation of a motor vehicle with a fuel cell system - Google Patents

Abstract

The technology disclosed herein relates to a method for predictively operating a motor vehicle with a fuel cell system. It includes the steps:
1.) Provision of cooling liquid, the at least two parallel-connected partial cooling circuits 10, 10 '; 20, 20 ', wherein a first partial coolant flow T ₁₀ , T ₁₀ ' flows through a first partial cooling circuit 10, wherein the first partial cooling circuit 10, 10 'supplies coolant to at least one first component of the fuel cell system, and wherein a second partial coolant flow T ₂₀ , T ₂₀ 'flows through a second partial cooling circuit 20, 20', wherein the second partial cooling circuit 20, 20 'supplies at least a second component of the fuel cell system with coolant; and 2.) adjusting the first and / or second partial coolant flow T ₁₀ , T ₁₀ '; T ₂₀ , T ₂₀ 'based on a future coolant requirement of the first component and / or the second component.

Description

The present application relates to a method for the predictive operation of a motor vehicle with a fuel cell system.

The cooling circuits for components of a fuel cell system are typically designed for continuous operation at full load or for particularly critical operating points (eg, uphill travel) (hereinafter: design operating points). The cooling circuits are designed so that in the ideal case in the design operating points all components simultaneously reach their maximum temperature. In real operation of a fuel cell system, the temperature maxima in the design operating points are not achieved simultaneously. Rather, a state in which the provided cooling amount is insufficient is already established earlier in one of the cooled system components. In order to avoid overheating of this component then the performance of the entire cooling system must be increased and / or the performance of the fuel cell system to be reduced (derating). If, for example, the temperature of the charge air cooler of the fuel cell system has reached the thermal limit, then the cooling capacity of the cooling system must be increased and, if appropriate, the output of the fuel cell to be delivered must also be reduced. Which component used to be limiting for the cooling system depends on many physical parameters and many component properties, eg. As operating parameters, heat absorption and heat dissipation behavior and heat capacity of the components, etc.

From the WO03 / 059664 is a motor vehicle with a fuel cell system, in which the cooling circuit for the fuel cell system and for the interior of the motor vehicle can be controlled by means of valves. The cooling system adjusts the cooling parameters based on instantaneous values. The system therefore reacts to measured instantaneous values. It comes due to the thermal inertia to a certain time delay. Since heat conditions change comparatively slowly, this time delay can lead to the vehicle, in particular the fuel cell system, not being or not always operated at the optimum operating point.

It is an object of the present application to reduce or remedy the aforementioned disadvantages. The object of the present invention is achieved by the subject matter of patent claim 1. The dependent claims represent advantageous embodiments.

A fuel cell system according to the technology disclosed herein includes at least one fuel cell and peripheral system components (BOP components) that may be used in the operation of the at least one fuel cell. A fuel cell includes, for example, an anode and a cathode, which are separated in particular by an ion-selective separator. The anode has a supply for a fuel to the anode. In other words, during operation of the fuel cell system, the anode is in fluid communication with a fuel reservoir. Preferred fuels for the fuel cell system are: hydrogen, low molecular weight alcohol, biofuels, or liquefied natural gas. The cathode has, for example, a supply or supply line for oxidizing agent. Preferred oxidizing agents are, for example, air, oxygen and peroxides. The ion-selective separator can be designed, for example, as a proton exchange membrane (PEM). Preferably, a cation-selective polymer electrolyte membrane is used. Materials for such a membrane include Nafion ^®, Flemion ^® and Aciplex ^®. For simplicity's sake, a system with a fuel cell is often discussed here. If a system component is listed below in the singular, the majority should also be included. For example, a plurality of fuel cells and partially a plurality of BOP components may be provided.

The method disclosed here is used for the predictive operation of a motor vehicle with a fuel cell system. In particular, it is a method for the predictive cooling of a fuel cell system.

The method comprises the step of providing cooling liquid, which is divided into at least two partial cooling circuits connected in parallel. It is therefore a cooling circuit, which is divided into two or more partial cooling circuits, which then run parallel to each other and are later brought together again to the one cooling circuit. A first partial coolant flow flows downstream of the distribution through a first partial cooling circuit. The first partial cooling circuit supplies at least a first component of a fuel cell system with coolant. A second coolant partial flow also flows downstream of the division by a second partial cooling circuit, wherein the second partial cooling circuit supplies at least one second component with coolant.

The method disclosed here further comprises the step: adaptation of the first and / or second partial coolant flow based on a future, in particular predicted, coolant requirement of the first component and / or the second component. The adaptation of the first and / or second partial coolant flow can be done by any suitable actuator, for example, controllable 3-way Valve (s), pumps, valves or chokes, etc. In particular, thermally activated chokes can be used, which are activated by an electric heater. By adapting the first and / or second partial coolant flow, the component can be specifically supplied with more coolant, the temperature of which is critical or becomes critical.

Advantageously, the operation of the components is thus anticipated in advance, in particular their cooling by adjusting the partial coolant flows. This prospective mode of operation of the fuel cell system or cooling system for future operating points or operating states can enable more efficient operation over further operating ranges of the fuel cell with the same cooling circuit configuration (eg same maximum cooling power that the radiator can provide the cooling circuit). In other words, the cooling circuit of the technology disclosed herein may be provided with a smaller radiator without the fuel cell being able to deliver less power.

The method preferably comprises the step of forecasting the future coolant requirement or required coolant partial flow of the first component and / or the future coolant requirement or required coolant partial flow of the second component. For example, for forecasting data can be evaluated, which allow conclusions about the future coolant requirement. For example, a driving behavior information, navigation information and / or environmental information can be evaluated for this purpose. For example, this information may be related to cooling center demand values stored in a database.

If, for example, a longer ascent is specified as the route, the controller can determine the future coolant requirement of the individual components, taking into account the route (eg length, gradient, speed limit) and the traffic volume (eg congestion or free travel) ,

The coolant requirement of the first component and / or the second component can preferably be predicted and / or adapted taking into account a driving behavior information, a navigation information and / or an environment information.

The driving behavior information representing the behavior of the driver is, for example, speed profile in the city, over land, on the highway; Switching behavior; etc. Preferably, the controller of the motor vehicle can recognize the driver on the basis of measured values, driver-specific inputs and / or driver-specific systems. Driver-specific systems are, for example, a key coding or a driver assigned to a mobile phone, which connects to the car. Driver-specific inputs are, for example, the profile selection or the selection of a stored seating position assigned to a driver, clearly assignable driving distance (path to work), mirror adjustment, etc. Another driver recognition device is, for example, a face recognition.

To determine the driving behavior, in particular also the vehicle sensor system or any input elements can be used. For example, the following factors can be taken into account: inclination sensor or gradient sensor, driving dynamics, lateral acceleration sensor, detection of pedal dynamics, driving experience switch, speed profile position of aerodynamic components, such as rear spoiler, etc. The controller is preferably able to analyze the driving behavior and a driver assigned. A driving behavior analysis may allow to more accurately predict the power requirements and to operate the fluid delivery device in a forward-looking manner. Advantageously, it is a learning control, for example. Based on Fuzzy Logic. Advantageously, the controller is also able to analyze recurring conditions and events, for example, based on acquired external parameters. Preferably, the controller is not only able to learn from the driving behavior of the driver, but also can also evaluate navigation information and environmental information and perform an optimized forecast of potential operating parameters. For example, the controller is configured to optimize recurring routes by a driver based on the lessons learned from previous trips. An example of this is, for example, the frequently traveled route between place of residence and place of work.

External parameters that represent navigation information are, for example, navigation parameters that include geoinformation, such as position, route and / or altitude profile information. Navigation information is also information about the driving cycle, ie the mix of city, overland and / or motorway part of the total route. Further navigation information is, for example, also traffic information, such as current or future traffic impairments. For example, current traffic jam messages or predictable traffic congestion due to major events, commuter traffic, special incidents and events, such as mass event, etc. to the navigation information. Navigation information is, for example, an intersection and / or a traffic light and / or a Traffic signal, which brings a comparatively short stop of the motor vehicle with it.

Furthermore, the navigation information may be a traffic light phase. The traffic light signal, for example, via a suitable communication signal, for. B. a radio signal and a suitable sensor can be detected on the motor vehicle.

Environmental information is, for example, current or future weather and / or room information, such as temperature, humidity, precipitation, wind speed, barometric pressure, etc.

Preferably, the method comprises the step of: adapting the first and / or second partial coolant flow already before the beginning of the period of time for which an altered, d. H. increased or decreased, coolant requirement of the first component and / or the second component is or was predicted. Thus, the coolant sub-streams are thus predictively changed in order to avoid early thermal overload. If a component is heated or cooled, so u passes. a. due to the heat capacity of the component a certain time until the temperature of the component changes. If now the coolant partial flows are changed predictively, the influence of the thermal inertia of the individual components can be reduced or compensated.

If, for example, a maximum power is requested by the system and it is clear, for example due to an approaching signal system, that this power has to be delivered only for a short time (eg less than one minute), the controller can divide the first and / or second coolant partial flow in such a way in that during this time the coolant flow to the fuel cell is increased and the coolant flow to the charge air cooler is reduced. This would tend to increase the temperature of the intercooler. Due to the thermal inertia, however, the charge air cooler temperature will scarcely change in this short period of time. The additional coolant flow to the fuel cell, however, has a faster effect on the operation of the fuel cell.

In the same way, the coolant flow to the fuel cell can preferably be increased and the coolant flow to the charge air cooler can be reduced during temporally limited peak powers. In this context, such a driver-requested peak power is understood as meaning a power which is above the maximum continuous decommissioning power of the fuel cell (hereafter: maximum continuous power) and which the fuel cell can deliver over a short period of time. The peak power can, for example, 110% to 120% of the max. Continuous power, for example, over a period of max. 30 seconds (for 120% continuous load) to 60% seconds (for 110% continuous load) can be provided. During operation of the fuel cell operating points may exist, the z. B. due to the membrane moisture and thus the ohmic resistance of the membrane can not be operated continuously. In part, these operating points may be due to higher BOP component loads, such. B. compressor performance can be compensated or damped in the short term. Thus, a low efficiency of BOP components is accepted in the short term to ensure high efficiency. This operation of the BOP component can, for. B. be thermally, limited in time.

The first and / or the second partial coolant flow can be adapted such that the first component and the second component are thermally equally loaded. Even if the two components can not be operated in the critical range, the coolant distribution on the two subcooling circuits can take place in such a way that both components are thermally equally loaded. For example, they can be operated at about 80% of their maximum temperature.

The first component and / or the second component may be supplied with more coolant than the future coolant requirement even before the beginning of the period for which there is a changed coolant requirement of the first component and / or the second component. For example, if it is predicted that the fuel cell temperature will become critical in a future stretch of road, it may begin to decrease the fuel cell temperature beforehand to counteract the heating. Thus, to a certain extent, cooling capacity or cooling capacity (hereinafter: cooling capacity) can be temporarily stored in the fuel cell.

In addition, however, cooling capacity in other components, for example in the intercooler, can also be temporarily stored. The charge air cooler is disposed upstream of the fuel cell stack. If this is cooled more than necessary in a partial load range of the fuel cell, it can use up this additional stored cooling capacity in a subsequent full-load period of the fuel cell. During the full load period, the controller may deliver less coolant than it would actually need to the intercooler due to the cooling power stored in the charge air cooler. This delta of coolant can then additionally come to the here temperature-critical fuel cell stack. The cooling system is thus relieved during a full load period by the caching of cooling power during a partial load period.

The first component may be a fuel cell stack, an oxidant charge air cooler, a cathode exhaust condenser, or a fuel tank heat exchanger of the fuel cell system. The second component may be a heat exchanger associated with the interior of the motor vehicle. In a further preferred embodiment, the first component may be the fuel cell stack and the second component may be the oxidant charge air cooler, the cathode exhaust condenser or a fuel tank heat exchanger. In a particularly preferred embodiment, the first component of the fuel cell stack and the second component of the intercooler.

The technology disclosed here will now be explained in more detail with reference to the figures. The 1 to 3 show schematic representations of cooling circuits.

The Indian 1 illustrated cooling circuit divides in the division K1, here designed as a 3-way valve, in two subcooling circuits 10 . 20 , which are respectively flowed through by a first and second coolant flow T ₁₀ , T ₂₀ . In these Teikühlkreisläufe 10 . 20 here are a fuel cell stack 50 (first component) and a charge air cooler 40 (second component) provided. The two Teikühlkreisläufe 10 . 20 finally open at a node K2 and then flow in a heat exchanger or radiator 60 in which that in the fuel cell stack 50 and the intercooler 40 heated coolant is cooled again. About the conveyor 30 the coolant then returns to the subcooling circuits 10 . 20 ,

If a change in the coolant requirement is now imminent, the first and / or second partial coolant stream T10, T20 can already be adjusted beforehand based on the predicted future coolant requirement of the first component and / or the second component. It is preferred that the thermal inertia of the components is taken into account, whereby a thermal overload of the components can be avoided.

An oxidizer conveyor 80 promotes via a Kathodenzuleitung 82 Oxidizing agent to the fuel cell stack 50 , The oxidant is injected into the fuel cell stack 50 in the intercooler 40 tempered. As already mentioned, the partial cooling circuits 10 . 20 arranged parallel to each other. Thus, the fuel cell stack 50 and the intercooler 40 thermally coupled with each other. Further, also provides the cathode lead 82 a certain thermal coupling of these two components. If the intercooler is cooled more, then it can adequately the oxidizing agent before entering the fuel cell stack 50 cool. This in turn means that for the fuel cell stack 50 less coolant needs to be provided. Furthermore, the components can 40 and 50 due to their mass and their heat capacity also at least to a certain extent store cooling capacity. These two effects make use of the technology disclosed here among others. If the fuel cell is operated, for example, in a partial load range and at the same time a full load operation, z. As a climb, predicted, the controller can already before the beginning of the full load cooling capacity in the fuel cell stack 50 , and preferably also in the intercooler 40 caching. For this purpose, the capacity of the conveyor 30 increased and / or the division of the fluid partial flows T ₁ , T _{2 are} adapted so that both components are optimally cooled, the instantaneous efficiency of the fuel cell system should also be considered. In full load operation can then first the capacity of the conveyor 30 be increased. Furthermore, the division of the fluid sub-streams can be optimized. It can be considered that in the intercooler 40 Cooling capacity is cached. In other words, the intercooler needs 40 during the following full load are not cooled to the extent that it would have to be cooled without the cached cooling performance. If the controller takes into account the cooling capacity cached in the intercooler, it can add comparatively more coolant to the fuel cell stack 50 provided the fuel cell is the thermally critical component. Of course, preference is also given by the controller in the fuel cell stack 50 cached cooling capacity taken into account. The cached cooling capacity does not have to be calculated. For example, it is sufficient that the temperatures of the components are known.

• – Einsatz von regelbaren 3-Wege-Ventilen in den Teilkühlkreisläufen,
• – Einsatz von zwei Pumpen in den Teilkühlkreisläufen,

As actuators, a wide variety of actuators can be provided. In addition to a 3-way valve 70 can also use two simple control valves 72 . 74 in the two partial cooling circuits 10 . 20 be provided (cf. 2 ). Furthermore, one or more pumps, throttles, and / or thermally activated pressure drop components may be provided. By introducing a stepless throttle in the cooling system, for example, before or after the fuel cell 50 or the intercooler 40 , the absolute coolant flow through the charge air cooler can 40 increase. The following alternative solutions are also possible:

• - use of controllable 3-way valves in the partial cooling circuits,
• Use of two pumps in the partial cooling circuits,

The valves or throttles can be actively controlled by a controller. In In a passive solution, the chokes can also be replaced by thermally activated components.

3 shows a more complex structure of a refrigeration cycle. The conveyor 30 , the oxidizing agent promoter 80 , the cathode lead 82 and the radiator 60 are the same as in the 1 and 2 , The intercooler 40 and the fuel cell stack 50 are also here in two subcooling circuits 10 . 20 arranged parallel to each other. Thus, the same effects and advantages occur here as in the previous ones 1 and 2 described. In addition, here are two subcooling circuits 10 ' . 20 ' shown, which are also arranged parallel to each other. The partial cooling circuit 10 ' is represented by a dashed line, wherein each of the following components stands alone as a first component of the first partial cooling circuit 20 ' can be considered: fuel cell stack 50 , Intercooler 40 for oxidant, cathode exhaust condenser 110 or a fuel tank heat exchanger 110 ,

The foregoing description of the present invention is for illustrative purposes only, and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 03/059664 [0003]

Claims (9)

Method for the predictive operation of a motor vehicle with a fuel cell system, comprising the steps of: providing coolant which is connected to at least two partial cooling circuits ( 10 . 10 '; 20 . 20 ' ), wherein a first partial coolant flow (T ₁₀ , T ₁₀ ') through a first partial cooling circuit ( 10 . 10 ' ), wherein the first partial cooling circuit ( 10 . 10 ' ) supplies at least one first component of the fuel cell system with coolant, and - wherein a second coolant partial flow (T ₂₀ , T ₂₀ ') through a second partial cooling circuit ( 20 . 20 ' ), wherein the second partial cooling circuit ( 20 . 20 ' ) supplies at least a second component of the fuel cell system with coolant; and - adapting the first and / or second coolant sub-streams (T ₁₀ , T ₁₀ ', T ₂₀ , T ₂₀ ') based on a future coolant requirement of the first component and / or the second component. The method of claim 1, wherein the coolant requirement of the first component and / or the second component is predicted and / or adjusted taking into account a driving behavior information, a navigation information and / or an environment information. The method of claim 1 or 2, wherein the first and / or the second partial refrigerant flow (T ₁₀ , T ₁₀ ', T ₂₀ , T ₂₀ ') is / are adjusted so that the first component and the second component are thermally equally loaded. Method according to one of the preceding claims, wherein the adjusting comprises the step of: adjusting the first and / or second partial coolant flow (T ₁₀ , T ₁₀ ', T ₂₀ , T ₂₀ ') already before the beginning of the period for which a changed coolant requirement of the first Component and / or the second component. The method of claim 4, wherein the coolant is already supplied to the first component and / or the second component before the beginning of the period for which there is a changed coolant requirement of the first component and / or the second component, as the future coolant requirement. The method of claim 5, wherein in the first component and / or in the second component cooling capacity is temporarily stored. Method according to one of the preceding claims, wherein the first component is a fuel cell stack ( 50 ), a charge air cooler ( 40 ) for oxidizing agent, a cathode exhaust condenser ( 110 ) or a fuel tank heat exchanger ( 110 ) of the fuel cell system, and wherein the second component is a heat exchanger ( 130 ), which is associated with the interior of the motor vehicle. Method according to one of the preceding claims, wherein the first component of the fuel cell stack ( 50 ), and wherein the second component is an intercooler ( 40 ) for oxidizing agent, a cathode exhaust condenser ( 110 ) or a fuel tank heat exchanger ( 120 ). Method according to one of the preceding claims, wherein increases during peak power times the coolant flow to the fuel cell and the coolant flow to the charge air cooler is reduced.

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