Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
  • H01M8/04097—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with recycling of the reactants
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
  • H01M8/04111—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants using a compressor turbine assembly
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
  • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
  • H01M8/04746—Pressure; Flow
  • H01M8/04753—Pressure; Flow of fuel cell reactants
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
  • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
  • H01M8/04746—Pressure; Flow
  • H01M8/04776—Pressure; Flow at auxiliary devices, e.g. reformer, compressor, burner
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
  • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
  • H01M8/04858—Electric variables
  • H01M8/04865—Voltage
  • H01M8/0488—Voltage of fuel cell stacks
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M2008/1095—Fuel cells with polymeric electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
  • H01M2250/20—Fuel cells in motive systems, e.g. vehicle, ship, plane
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02T90/40—Application of hydrogen technology to transportation, e.g. using fuel cells

Definitions

• the invention relates to a method for operating a fuel cell system in a vehicle, according to the closer defined in the preamble of claim 1.
• stop / start systems are known in vehicles.
• motor vehicles of any type of drive it is customary in the meantime to save energy and to reduce noise emissions, in short phases, in which no power is needed, for example at an intersection, a red light or when rolling the vehicle to turn off the drive unit so To save energy.
• auxiliary consumers such as pumps, compressors and
• Fuel cell system are equipped to generate the necessary drive power.
• US Pat. No. 6,484,075 B2 describes a method for temporarily placing a fuel cell in a stop mode for the duration of a vehicle stop. Starting from a request of the vehicle to change to a stop mode of the fuel cell system is first checked whether the
• Fuel cell system is able to meet this requirement. If this is the case, it switches to a stop mode in which both the
• Fuel gas supply and the air supply to the fuel cell are completely switched off. This saves energy and emissions. However, that has it there
• the fuel cell can deliver no drive power.
• Stop mode the electrical contact of the fuel cell is maintained, a current can still be drawn from the fuel cell, so that residual media, and in particular residual oxygen in the fuel cell, are degraded. As a result, harmful voltages during the stop mode are avoided for the individual cells of the fuel cell, which would adversely affect the life of the cell.
• fuel gas in particular hydrogen available for the degradation
• Fuel cell not interrupted, but only shut down to a reduced pressure. In this way, when the air supply of the cathode region of the fuel cell is switched off or minimized, an excessively large differential pressure between the anode region and the cathode region can be prevented. If the fuel cell, as it is according to a particularly preferred embodiment, is designed as a PEM fuel cell, this reduced pressure difference ensures that the membranes of the fuel cell are spared accordingly and not too high
• the fuel cell electrically with a
• Electronic unit coupled to decrease the power of the fuel cell, which also allows excess power of the fuel cell in one
• an energy storage device such as a battery before.
• the design has the decisive advantage that when entering the stop mode, first a current through the electronics unit from the fuel cell is removed. This current causes the voltage to be kept correspondingly low, so that no corrosion occurs in the region of the individual cells in the fuel cell.
• a favorable limit for the voltage is about 0.85 volts per single cell.
• residual oxygen present in the cathode region is dissipated via the stream, since the latter can react with the fuel gas, since the fuel gas supply according to the invention continues to run at a low level.
• the voltage is kept at a predetermined low level via the electronics unit, in order to continue to maintain the operational readiness.
• this low voltage level which is then typically applied to the entire high-voltage bus of the fuel cell system, a reliable operation thereof, since this is for example also responsible for the drive of the recirculation conveyor. It may well happen that a negative current flows into the fuel cell, the power required for this can be removed from the energy storage device and is typically very low.
• the air delivery device is completely stopped when changing to the stop mode.
• This structure which is particularly easy to implement, especially when using volumetric compressors and the like, since they can restart very quickly and provide a maximum air flow, is very favorable in terms of noise emissions and energy requirements.
• Air mass flow is performed, being switched back to the stop mode after reaching a predetermined value of the air mass flow. This brief start of the air conveyor temporarily creates a
• Air mass flow is temporarily increased and the other processes and
• this refresh is associated with a relatively low energy consumption only low and noise emission. However, it can provide a significant advantage in terms of corrosion and thus the life of the fuel cell.
• a flow compressor is used as the air conveyor, which continues to run at a predetermined low speed during the stop mode.
• Flow compressor which via a blower or the like
• Air mass flow promote the fuel cell are known from the general state of the art in fuel cell systems and have corresponding advantages over volumetric compressors.
• flow compressors require a comparatively high speed in order to be able to provide the delivered air mass flow.
• a stop mode such a flow compressor is therefore not completely stopped, but continues to run according to the invention at a low speed.
• This has the advantage that it must be far less accelerated when restarting the system, which has decisive advantages in terms of energy requirements and the time to restart the fuel cell system.
• Another aspect of this further running of the flow compressor as an air conveyor at a low speed is that further a low air mass flow is conveyed to the fuel cell, so that the above-described refresh in this embodiment of the inventive method can typically be omitted.
• a flow connection is opened.
• a flow connection which could also be referred to as a system bypass valve, thus creates a flow connection from a region downstream of the air conveying device into the exhaust gas region.
• FIG. 1 is a highly schematically indicated vehicle with a fuel cell system
• FIG. 2 shows a fuel cell system in a first possible embodiment
• FIG. and FIG. 3 shows a fuel cell system in a second possible embodiment.
• a vehicle 1 is shown very highly schematically, which can be moved by means of an electric drive motor 2, which drives two wheels 3 indicated here.
• the vehicle 1 has a fuel cell system 4, which is the electrical drive energy for the engine 2 and thus ultimately for driving the
• Vehicle 1 provides. This is indicated in the illustration of Figure 1 via electrical lines which connect the fuel cell system 4 and the drive motor 2 via an electronic unit 5 with each other. As indicated by the two dashed arrows, the electronic unit 5 is also in correspondence with the fuel cell system 4, for example, values of sensors in the
• Fuel cell system 4 which monitor this in terms of pressure, temperature and the like to be able to query.
• the electronic unit 5 is also in
• vehicle control unit 6 which is provided in a manner known per se for controlling the vehicle.
• vehicle control unit 6 is also involved with sensors and actuators, not shown here the vehicle 1 in conjunction and can, for example, acceleration values, an accelerator pedal position as a reference for the driver's desired power request and the like evaluate.
• the vehicle in the illustration of Figure 1 is now to have a so-called stop / start system.
• a stop / start system ensures that a drive unit of the vehicle 1, in this case the fuel cell system 4, always changes into a standby or stop mode, if temporarily none
• Fuel cell 7 which should be constructed here as a stack of PEM fuel cells. According to this construction, the fuel cell 7 has a cathode space 8 and an anode space 9, which through the proton-conducting membranes 10th
• the cathode chamber 8 is connected via an air conveyor 11, which here as a volumetric compressor, for example as a screw or
• Roots compressor should be formed, provided via an air supply line 12, an air mass flow available.
• the oxygen contained in this air mass flow now at least partially reacts in the region of the fuel cell 7 with a fuel gas stream fed to the anode chamber 9 of the fuel cell 7.
• This fuel gas stream should be a hydrogen stream in the embodiment shown here. This will be the
• Valve device 14 provided on a controllable predetermined pressure level.
• the storage device 13 is designed in particular as a high-pressure accumulator, in which the hydrogen is stored at a very high pressure, for example 350 or 700 bar.
• a gas generating device instead of using under pressure stored hydrogen, it would of course also conceivable to use instead of the memory device 13, a gas generating device in which
• hydrogen could be generated from a hydrocarbonaceous feedstock.
• Exhaust pipe 15 is discharged from the cathode compartment 8.
• the hydrogen is typically not completely converted, since even alone to supply all areas of the anode uniformly with hydrogen, a corresponding excess of hydrogen via the valve device 14 is metered into the anode chamber 9.
• the unconsumed hydrogen is therefore recirculated via a recirculation line 16 and a recirculation conveyor 17 and returns with fresh from the storage device 13 originating hydrogen back into the anode compartment 9.
• the recirculation conveyor 17 is to be formed in the embodiment shown here as a hydrogen circulation fan 17 which is driven by an electric motor.
• inert gas now accumulates, which has diffused through the membranes 10 out of the region of the cathode space 8 into the anode space 9.
• inert gas now accumulates, which has diffused through the membranes 10 out of the region of the cathode space 8 into the anode space 9.
• a part of the product water is formed in the
• a valve 18 is provided, via which discontinuously from time to time water and / or gas can be discharged from the field of anode recirculation.
• the one valve 18 shown here which is used as a combined valve for the so-called drain (the discharge of water) and the purge (the discharge of gas)
• two valves would be conceivable, on the one hand for the discharge of water and on the other are intended for the discharge of gas.
• these two functionalities may be combined in the valve 18, which is for this purpose in preferred manner in a water separator, which is not shown here, is arranged.
• the drained via the valve 18 water and / or gas then passes into the region of the supply air line 12 to be used together with the over
• Air conveyor 11 funded supply air to enter the cathode compartment 8.
• the cathode chamber 8 is possibly in the discharged via the valve 18 gas
• Fuel cell system 4 occur out.
• the registered water is vaporized in the dry and after the air conveyor 11 hot air supply and moistens them accordingly. Excess water is discharged via the exhaust pipe 15 together with the product water.
• a humidifier 19 can be seen.
• a humidifier 19 may be arranged, for example, for water vapor permeable, for air and exhaust gas impermeable membranes.
• the air mass flow now flows in the supply air line 12, while on the other side of the membranes, the moist exhaust gas flow laden with the product water flows in the exhaust gas line 15.
• This results in a moisture balance between the individual mass flows so that after the air conveyor 11 typically hot and dry supply air is humidified by the present in the exhaust gas product water.
• the so cooled and humidified supply air is far better tolerated for the membranes 10, as a non-humidified air.
• the humidifier 19 optionally shown here can also be dispensed with.
• Control device which may be part of the electronic unit 5, for example, now the fuel cell system 4 is checked to see whether the present
• Fuel cell system 4 does not provide power to the vehicle 1 during such a stop mode, but remains unlike a final shutdown of the vehicle
• Fuel cell system 4 and the vehicle 1 in a mode from which a restart in a very short period of time, in particular less than a second is possible.
• the fuel cell 7 remains electrically connected to the electronic unit 5, so it is electrically not switched off.
• the air conveyor 11 is stopped in the event that it is a fuel cell system according to Figure 2, the pressure supply of the anode chamber 9 with hydrogen is reduced to a low pressure level.
• the recirculation conveyor 17 continues to operate, but with a much lower mass flow. Typically, this can be achieved by reducing the speed of rotation in this embodiment
• Hydrogen recirculation blower trained recirculation conveyor 17 done.
• the valve 18 since no air mass flow through the supply air line 12 is available, the valve 18 must remain closed during the stop mode, even if this is due, for example, to a timing during a stop mode for the drain and / or purge of water and / or gas should be opened.
• the control for the stop mode must therefore have priority here so that the valve 18 remains closed during the duration of the stop mode in any case. Since only a minimal or no current is drawn from the fuel cell 7 during the stop mode, there may be an increase in the hydrogen pressure in the anode chamber 9. This pressure must therefore be monitored accordingly and regulated to a predetermined pressure window or a predetermined low pressure level. Such a pressure level could, for example, be between 0.03 bar as the minimum hydrogen pressure and 0.6 bar as the maximum hydrogen pressure.
• Fuel cell 7 drop accordingly.
• the residual oxygen in the cathode space 8 is thereby consumed, the current can, for example, in an end plate heating the Fuel cell 7 or used in other auxiliary consumers.
• hydrogen permeation through the membranes 10 or slight leakage of hydrogen will enter the cathode compartment 8 which will react with the oxygen.
• Fuel cell system 4 is supplied with a voltage which continues to ensure a functionality of the high-voltage bus, and which, for example, for driving the recirculation conveyor 17 is required. In addition, by the
• the voltage can be kept at this constant level via the electronics unit 5, which comprises a DC / DC converter, for example.
• the required power can be from a
• Energy storage device are provided, which the vehicle 1 typically has.
• Such an energy storage device which may be, for example, a battery or a high-performance capacitor or a combination of these components, is typically present in electrically powered vehicles 1 anyway. Does it come to a surplus in the area of
• Energy storage device are cached. Even when braking the vehicle 1 power can be obtained by a large part of the braking torque is not applied via friction brakes, but via a regenerative operation of the drive motor 2. The thus recovered electrical energy can also be stored in the energy storage device and used for example for restarting.
• the energy storage device is thus able in such a vehicle 1, even without the fuel cell system 4 is operated or actively outputs power to provide an at least small amount of power. This is sufficient to keep the voltage in the region of the fuel cell stack 7 constant. It is important to ensure that the individual cells of the fuel cell 7 a slight tolerate negative current without being adversely affected in their performance and lifetime.
• the time sequence begins again until the cell voltages diverge again so that individual cells come into a critical state. If the stop mode lasts more than two periods, it comes after renewed expiry of the period to a second refresh. If the stop mode continues to be obtained, theoretically a third refresh may also be carried out, with a change typically being made from the stop mode to the finally switched-off mode of the fuel cell system 4 after a predetermined time has elapsed. Such a predetermined time can typically be on the order of 2 to 3 of the time periods up to a refresh.
• Fuel cell system 4 is constructed. Only the air conveyor 11 is in the embodiment of the fuel cell system 4 shown here as
• the air conveyor 11 is intended to be part of a so-called electric turbocharger 20, which in addition to the flow compressor 11 also has a turbine 21 and an electric machine 22.
• the construction of the electric turbocharger 20, which is also referred to as ETC (Electric Turbo Charger), is known in principle from the prior art.
• ETC Electric Turbo Charger
• the air delivery to the fuel cell 7 takes place here via the flow compressor 11, which is driven by the electric machine 22 as needed.
• the exhaust gas coming from the cathode chamber 8 via the exhaust gas line 15 is expanded via the turbine 21, so that the energy recovered from the exhaust gas flow is likewise absorbed by the exhaust gas flow
• Flow compressor 11 can be provided. If, in special situations and operating states of the fuel cell system 4, the energy consumption of the flow compressor 11 is very low, it may be that more power is provided at the turbine 21 than the flow compressor 11 requires. In this case, the electric machine 22 can be operated as a generator to store this power in the above-mentioned energy storage device.
• Fuel cell system 4 substantially comparable to the fuel cell system already explained in the context of Figure 2 due to the fact that the electric turbocharger in regular operation at very high speeds of
• Air conveyor is used, this not completely stopped, but runs at a correspondingly predetermined minimum speed in the order of 10 - 12,000 U / min, on.
• a small mass air flow is also conveyed into the cathode compartment 8 in the stop mode. This ensures that constantly a small amount of current has to be drawn from the fuel cell 7 in order to limit the voltage accordingly. But this stream can, for example, to drive the
• Fuel cell 7 would be feared.
• the system bypass valve 23 may be provided. It can not only actively stealgeamidete air mass flows largely without passage of the
• Cathode space 8 to conduct the system, but also an air mass flow, which penetrates, for example, due to a dynamic pressure in the supply air line 12, for example, when descending the vehicle 1, derived accordingly.

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• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Fuel Cell (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

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Cited By (6)

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• 2009
  • 2009-08-05 DE DE102009036199A patent/DE102009036199A1/de not_active Withdrawn
• 2010
  • 2010-07-19 CN CN201080034573.6A patent/CN102640339B/zh active Active
  • 2010-07-19 US US13/388,898 patent/US9034529B2/en active Active
  • 2010-07-19 JP JP2012523218A patent/JP5629772B2/ja active Active
  • 2010-07-19 WO PCT/EP2010/004379 patent/WO2011015282A1/de not_active Ceased
  • 2010-07-19 EP EP10737279.9A patent/EP2462647B1/de active Active

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