WO2016083365A1

WO2016083365A1 - Method for predictively operating a motor vehicle with a fuel cell system

Info

Publication number: WO2016083365A1
Application number: PCT/EP2015/077486
Authority: WO
Inventors: Max Eschenbach; Johannes Schmid; Maximilian Zettl
Original assignee: Bayerische Motoren Werke Aktiengesellschaft
Priority date: 2014-11-28
Filing date: 2015-11-24
Publication date: 2016-06-02
Also published as: DE102014224380A1; CN106716697A; CN106716697B

Abstract

The invention relates to a method for predictively operating a motor vehicle with a fuel cell system. The method comprises the following steps: 1.) providing cooling fluid that is distributed to at least two partial cooling circuits (10, 10'; 20, 20') connected in parallel, wherein a first coolant partial flow (T₁₀, T₁₀') flows through a first partial cooling circuit (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 (T₂₀, T₂₀') flows through a second partial cooling circuit (20, 20'), wherein the second partial cooling circuit (20, 20') supplies at least one second component of the fuel cell system with coolant; and 2.) adapting the first and/or second coolant partial flow (T₁₀, T₁₀'; T₂₀, T₂₀') based on a future coolant requirement of the first component and/or the second component.

Description

Method for the predictive operation of a motor vehicle with a

The fuel cell system

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 (e.g., uphill travel) (hereafter: excavation operating points). The

Cooling circuits are designed so that, ideally, in the

Design operating points all components simultaneously reach their maximum temperature. In the real operation of a fuel cell system, the

Temperature maxima in the design operating points are not reached 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). For example, if the temperature of the intercooler of the

Fuel cell system has reached the thermal limit, the cooling capacity of the cooling system must be increased and possibly also the output of the

Fuel cell can be reduced. Which component used to be limiting for the cooling system depends on many physical parameters and many

Component properties, e.g. Operating parameters, heat absorption and

Wärmeabgabeverhaiten and heat capacity of the components, etc.

From WO03 / 059664 a motor vehicle with a fuel cell system is known, in which the Kühlkreisiauf for the fuel cell system and for the interior of the motor vehicle can be controlled by means of valves. The cooling system fits the

Cooling parameters based on instantaneous values. The system thus reacts to measured instantaneous values. It comes due to the thermal inertia to a certain time delay. Because heat conditions are

change relatively slowly, this time delay can cause the vehicle, in particular the fuel cell system is not or not always operated at the optimum operating point.

It is an object of the present application to reduce the aforementioned disadvantages or to remedy. The object of the present invention is solved by The subject matter of claim 1. The dependent claims are 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, for example, as

Proton exchange membrane (PEM) may be formed.

Preferably, a cation-selective polymer electrolyte membrane is used.

Materials for such a membrane are: Nation®, Flemion® and Aciplex®. For simplicity's sake, a system with a fuel cell is often discussed here. If one

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 herein further includes the step of: adapting the first and / or second coolant sub-streams 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 throttles, etc. In particular, thermally activated throttles can be used, which via an electric heater to be activated. 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, therefore, anticipatory in advance on the operation of the

Components acted, in particular their cooling by adjusting the partial coolant flows. This prospective mode of operation of the fuel cell system or the cooling system for future operating points or operating states of the

Fuel cell systems that are in particular to be started or requested in the future may, with the same cooling circuit configuration (for example, the same maximum cooling power that the radiator of the cooling circuit can provide) enable more efficient operation over further operating ranges of the fuel cell. In other words, the

Cooling circuit of the technology disclosed here are equipped with a smaller radiator, without the fuel cell can deliver less power.

Preferably, the method comprises the step: 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 future operating points or operating states of the

Fuel cell system, which are approached or requested in particular in the future. For example, for forecasting, data may be evaluated

Allow conclusions about future coolant requirements. For example, a driving behavior information, a navigation information and / or a

Environment information to be evaluated. For example, this information may be related to cooling center demand values stored in a database.

If, for example, a longer uphill journey is specified as the route, then the controller can, inter alia, taking into account the route (eg length, inclination, Speed limit) and / or the traffic volume (eg congestion or free travel) determine the future coolant requirement of the individual components.

The coolant requirement of the first component and / or the second component may preferably take into account a driving behavior information, a

Navigation information and / or environmental information can be predicted and / or adapted.

The behavior of the driver representing driving behavior is, for example, the speed profile in the city, overland, on the highway; Switching behavior; etc. The control of the motor vehicle may be based on measured values,

driver-specific inputs and / or driver-specific systems recognize the driver. 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 travel route (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, recognition 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 assign a driver. 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

Evaluate navigation information and environmental information and perform an optimized forecast of potential operational parameters. For example, the controller is configured to optimize recurring routes by a driver based on the lessons learned from previous trips. One An example of this is, for example, the frequently traveled route between place of residence and workplace.

External parameters that represent navigation information are, for example.

Navigation parameters that include geoinformation, such as position, route and / or elevation profile information. Navigation information is also information about the drive cycle, i. 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 jams or predictable ones count

Traffic congestion due to major events, commuter traffic, special incidents and events, such as mass event, etc. to the

Navigation information. A navigation information is, for example, an intersection and / or a traffic light and / or a traffic signal signaling, which brings a comparatively short stop of the motor vehicle with it.

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

Environmental information is, for example, current or future weather and / or

Room information, eg temperature, humidity, precipitation,

Wind speed, air pressure, etc.

The method preferably comprises the step: adaptation of the first and / or second partial coolant flow already before the beginning of the period of time for which a changed, ie increased or reduced, coolant requirement of the first component and / or the second component has existed or predicted. Thus, the cooling medium flows are thus predictively changed in order to avoid early thermal overload. When a component is heated or cooled, a certain amount of time elapses, inter alia, due to the heat capacity of the component, 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. For example, if a maximum power is requested by the system and is

For example, because of an approaching S ignalanlage clear that this power only for a short time (eg less than a minute) must be submitted, the controller may divide the first and / or second partial coolant stream such that during this time the coolant flow to the fuel cell increases and the coolant flow to the intercooler 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, it is preferable for the coolant flow to the fuel cell to be increased and the coolant flow to the charge air cooler to be reduced during temporally limited future peak powers. In this context, such a driver-requested peak power is understood as meaning a power which is above the maximum continuous power output of the fuel cell (hereinafter: 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. In operation of the fuel cell, operating points may exist, e.g. 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 as Compressor performance, short-term compensated or damped. Thus, a low efficiency of BOP components is accepted in the short term to ensure high efficiency. This operation of the BOP component can be accomplished, e.g. thermal, 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 to the two partial cooling circuits can be carried out 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 coolant may be supplied to the first component and / or the second component before the beginning of the time period for which there is a changed coolant requirement of the first component and / or the second component, as the future coolant requirement. For example, it is predicted that in a future

Section, the fuel cell temperature becomes critical, so it can already be started before to reduce the fuel cell temperature to the

To counteract warming. 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 fail due to the

Intercooler stored cooling power the intercooler less coolant than he would actually need. 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, a charge air cooler for

Oxidizing agent, 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. Figures 1 to 3 show schematic representations of cooling circuits. The cooling circuit shown in FIG. 1 is divided in the division K1, here designed as a 3-way valve, in two partial cooling circuits 10, 20, which are respectively flowed through by a first and second coolant flow T10, T20. In this Teikühlkreisläufen 10, 20 here a fuel cell stack 50 (first component) and a charge air cooler 40 (second component) are provided. The two Teikühlkreisläufe 10, 20 finally open at a node K2 and then flow in a heat exchanger or cooler 60, in which the heated in the fuel cell stack 50 and the intercooler 40 coolant is cooled again. Via the conveyor 30, the coolant then returns to the partial cooling circuits 10, 20th

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 80 delivers via a cathode feed line 82 oxidizer to the fuel cell stack 50. The oxidant is before entering the

Fuel cell stack 50 tempered in the intercooler 40. As already mentioned, the partial cooling circuits 10, 20 are arranged parallel to one another. Thus, the

Fuel cell stack 50 and the intercooler 40 thermally coupled together. Furthermore, the cathode feed line 82 also represents a certain thermal coupling of these two components. If the charge air cooler is cooled more strongly, it can adequately cool the oxidizing agent before it enters the fuel cell stack 50. This in turn means that less fuel must be provided to the fuel cell stack 50. Further, due to their mass and heat capacity, components 40 and 50 may also store cooling capacity at least to some extent. These two effects make the technology disclosed here, i.a. advantage. Will the

Fuel cell operated, for example, in a partial load range and at the same time a full load operation, e.g. an uphill, predicted, so the controller can even before the beginning of the full load cooling capacity in the fuel cell stack 50, and preferably in the intercooler 40, caching. For this, the delivery rate of

Fördereinrichtun g 30 increased and / or the division of the fluid partial flows Ti, T _{2 are} adjusted so that both components are optimally cooled, the momentary efficiency of the fuel cell system should also be considered. In full load operation, the delivery rate of the conveyor 30 can then be increased first. 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 charge air cooler 40 does not have to be cooled to the extent that it would have to be cooled without the cached cooling power during the following full load. If the controller takes into account the cooling capacity temporarily stored in the intercooler, it can supply comparatively more coolant to the fuel cell stack 50, provided the fuel cell is the thermally critical component.

Of course, the controller also takes into account the cooling capacity temporarily stored in the fuel cell stack 50. The cached

Cooling capacity does not have to be calculated. For example, it is sufficient that the temperatures of the components are known.

As actuators, a wide variety of actuators can be provided. In addition to a 3-way valve 70 and two simple control valves 72, 74 in the two

Part cooling circuits 10, 20 may be provided (see Fig. 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 intercooler 40 can be increased. The following alternative solutions are also possible:

o use of controllable 3-way valves in the partial cooling circuits,

o use of two pumps in the partial cooling circuits,

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

Fig. 3 shows a more complex structure of a refrigeration cycle. The conveyor 30, the oxidant conveyor 80, the cathode feed line 82 and the radiator 60 are the same as in Figures 1 and 2. The intercooler 40 and the

Fuel cell stack 50 are also arranged here in two subcooling circuits 10, 20 parallel to each other. Thus, the same effects and advantages occur here as already described with reference to FIGS. 1 and 2. In addition, here are two partial cooling circuits 10 ', 20' shown, which are also parallel angeord net. The partial refrigeration circuit 10 'is represented by a dashed line, wherein each of the following components may be considered as a first component of the first partial refrigeration circuit 20': fuel cell stack 50, oxidizer charge air cooler 40, cathode exhaust condenser 110, or 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.

Claims

claims

1. A method for the predictive operation of a motor vehicle with a

Fuel cell system, with the steps:

Providing cooling liquid which is split up into at least two partial cooling circuits (10, 10 '; 20, 20') connected in parallel,

wherein a first coolant partial flow (ΤΊο, ΤΊο ') by a first

Part cooling circuit (10, 10 ') flows, wherein the first partial cooling circuit (10, 10') supplies at least a first component of the fuel cell system with coolant, and

wherein a second coolant partial flow (T20, T20 ') through a second

Partial cooling circuit (20, 20 ') flows, 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 partial coolant flow (Ti ₀ , Tio ', T ₂ o, T20') based on a future coolant requirement of the first component and / or the second component for future operating points and / or operating conditions of the fuel cell system.

2. The method of claim 1, wherein the coolant requirement of the first component and / or the second component taking into account a

Driving behavior sinformation, navigation information and / or a

Environment information is predicted and / or adjusted.

3. The method according to claim 1 or 2, wherein the first and / or the second

Coolant partial flow (T10, T10 ', T20, T20') is / are adapted such that the first component and the second component are thermally equally loaded.

4. The method of claim 1, wherein the adjusting comprises the step:

Adjusting the first and / or second partial coolant flow (T ₁₀ , Tio ', T2o, T20') already before the beginning of the period for which there is a changed coolant requirement of the first component and / or the second component.

5. The method of claim 4, wherein the first component and / or the second component already before the beginning of the period for which a changed

Coolant requirement of the first component and / or the second component is more coolant than the future coolant requirement is supplied.

6. The method according to claim 5, wherein in the first component and / or in the

second component cooling capacity is cached.

7. The method according to any one of the preceding claims, wherein the first component, a fuel cell stack (50), an intercooler (40) for oxidizing agent, a

Cathode exhaust condenser (110) or a fuel tank heat exchanger (1 0) of the fuel cell system, and

wherein the second component is a heat exchanger (130) associated with the interior of the motor vehicle.

8. The method of claim 1, wherein the first component is the fuel cell stack (50), and wherein the second component is an oxidant charge air cooler (40), a cathode exhaust condenser (110) or a

Fuel tank heat exchanger (120) is.

9. The method according to any one of the preceding claims, wherein during time

limited peak power increases the flow of coolant to the fuel cell and the coolant flow to the charge air cooler is reduced.

10. The method according to any one of the preceding claims, wherein the cooling liquid is a deionized cooling liquid. 1. The method according to any one of the preceding claims, wherein the future

Coolant requirement of the first component and / or the second component is determined taking into account a route and / or the traffic volume.

12. The method according to any one of the preceding claims, wherein the first and / or second coolant partial flow (ΤΊο Ti _0th '; T ₂ o, T20') are adjusted based on the findings of previous trips repetitive journeys.

13. The method according to any one of the preceding claims, wherein when a maximum

Power demanded by the fuel cell system and due to an approaching Signaling system is predicted that this power will be delivered only for a short time m uss, the first and / or second partial refrigerant flow will divide in such a way that during this time the coolant flow to

Fuel cell stack increased and the flow of coolant to a charge air cooler can be reduced.

Method according to one of the preceding claims, wherein before starting a full load operation cooling capacity in the fuel cell stack, and preferably also in the intercooler, cached when the fuel cell system is operated in a partial load range and zeitgieich a full load operation, especially a mountain trip, is predicted.