DE20122193U1 - Fuel cell system with anode catalyst, has circuit producing voltage pulses to clear substances poisoning anode, by electrochemical oxidation - Google Patents

Abstract

The circuit (20) includes a pulse generator (40) producing pulses of variable shape (21). Switching components (22, 23) are opened and closed by the pulses. The resultant voltage signals can be used to oxidize substances electrochemically, on the anode.

Description

The present invention relates to a fuel cell system with one or more fuel cells, each fuel cell being an anode-electrolyte-cathode unit and has an anode catalyst. The fuel cell system also has a Circuit arrangement for generating voltage pulses and for impressing the Voltage pulses on the fuel cell (s).

Fuel cells have been around since long known and especially in the automotive industry has grown significantly in importance in recent years.

In a fuel cell, for example a PEM fuel cell, electricity is generated by a chemical reaction generated. A fuel, such as hydrogen, and an oxidizing agent such as oxygen from the Air, electrical energy and a reaction product such as Water, converted. A fuel cell essentially exists of an anode part, a membrane (electrolyte) and a cathode part. The Membrane consists of a gas-tight and proton-conducting material and is arranged between the anode and the cathode to hold ions exchange. On the side of the anode, the fuel is supplied while on the oxidant is supplied to the side of the cathode. Be on the anode by catalytic reactions protons or hydrogen ions, generated that move through the membrane to the cathode. On the cathode the hydrogen ions react with the oxygen and it forms themselves water. Leave the electrons released during the reaction are conducted as electrical current through a consumer.

If you want the fuel cell with an easily available or fuel to be stored such as natural gas, methanol, gasoline, diesel or operate the like, you have to the hydrocarbon in a production / processing arrangement of a fuel first convert into a hydrogen-rich gas. This essentially becomes decomposed to hydrogen and carbon dioxide. Furthermore also arises Carbon monoxide, the one for the fuel cell harmful Represents gas since it ineffective the catalyst on the anode side makes and therefore before the fuel enters the fuel cell must be removed.

In the fuel cell, the carbon monoxide, but also others for the fuel cell harmful Substances above a certain concentration cause that of the fuel cell output reduced and consequently the efficiency of the Fuel cell is greatly reduced.

In order to prevent such a harmful influence of carbon monoxide on the fuel cell, the DE 197 10 819 C1 described a fuel cell in which performance losses due to impurities absorbed on the anode catalyst are to be avoided. This is achieved in that the fuel cell is connected to means which impart a positive voltage pulse to the anode of the fuel cell. A pulse-shaped change in the anode potential is brought about by impressing the voltage pulse. As a result of these pulsed changes in the anode potential, the carbon monoxide in the fuel cell is oxidized (detoxification of the fuel cell).

The invention is based on the object To further develop the fuel cell system of the type mentioned at the beginning, that the Voltage pulses to detoxify the fuel cell in a simple manner the fuel cell imprinted can be.

The task is solved by the Features of the fuel cell system according to protection claim 1 and protection claim 2. Other advantages, features, effects, details and aspects of present invention result from the dependent claims, the Description as well as the drawings. Features and details in the Described in connection with the first aspect of the invention apply of course also for the second aspect of the invention, and vice versa.

The basic idea of the present invention is as in the DE 197 10 819 C1 , the disclosure content of which is included in the description of the present invention, in that the fuel cell (s), or the anode catalyst of the fuel cell (s), is / are freed from harmful constituents, in particular carbon monoxide, by applying the voltage pulses ( Detoxification) by oxidizing it. A pulse-shaped change in the anode potential is brought about by the stamping of the voltage pulses. The present invention describes in particular advantageous configurations of a circuit arrangement provided for impressing the voltage pulses.

According to the first aspect of the invention a fuel cell system provided, with at least one Fuel cell, the fuel cell being an anode-electrolyte-cathode unit as well has an anode catalyst, and with a circuit arrangement for generating voltage pulses and for impressing the voltage pulses the fuel cell. According to the invention, the fuel cell system is thereby characterized that the Circuit arrangement a pulse generator for generating variable pulsed Signals that the Circuit arrangement has at least one switch element, the through the pulsed Signals open and is closed and that about the pulsed Signals voltage pulses are generated, by means of which electrochemically oxidizable Substances on the anode are oxidized or are oxidizable.

A basic idea of the invention Fuel cell system consists in that at least one switch element of the circuit arrangement is opened and closed via the pulse-shaped signals. Corresponding components in the circuit arrangement are then activated or activated via the switch element which detoxify the fuel cell. This will be explained in more detail in the further course of the description with the aid of a few non-exclusive examples.

Another basic idea of the fuel cell system according to the invention is that the pulsed Signals are generated by means of a pulse generator, the pulse generator is designed such that variable pulsed Signals can be generated. Through variability the pulse-shaped Signals the effect of the circuit arrangement can be optimized so that detoxification the fuel cell becomes possible with high efficiency.

The invention is not specific Types of pulse generators limited. It is only important that the Pulse generator pulse-shaped Can generate signals and that the pulsed Signals are suitable, the at least one switching element in a corresponding Way to open and / or close. This can be accomplished, for example, by the pulse generator generates corresponding voltage pulses, the voltage pulses opening or Conclude cause the switch element. It is also conceivable that the pulse generator pulsed Generated signals based on light, radio or the like.

By in the circuit arrangement provided pulse generator it is consequently made possible for the fuel cell (s) impressed Regulate or control voltage pulses, so that ever Depending on the operating situation and operating condition, voltage pulses with different Size and shape generated and can be imprinted on the fuel cell.

The pulse generator can be advantageous for generating essentially rectangular, pulse-shaped signals be trained. Such signals allow due to their steep Flank an exact switching within the circuit arrangement. Advantageous can the pulse-shaped Signals a variable pulse duration and / or a variable pulse interval and / or a variable pulse frequency and / or a variable pulse amplitude exhibit. The invention is not limited to specific values individual parameters limited. Advantageous pulse durations can for example - however not exclusively - in the area move between 10 milliseconds and 2 seconds. Non-exclusive examples for suitable pulse intervals are in the range between 500 milliseconds and 10 seconds.

The pulse generator can be advantageous a circuit for calibration of the pulse duration of the pulse-shaped signals exhibit. When using such a circuit, the pulse frequency for example, be fixed. Also the pulse duration and the pulse interval are essentially fixed. About the circuit is only calibrated the pulse duration, which means that a fine adjustment of the Pulse duration can be made. With this embodiment is a more or less "rigid" option for generating pulse-shaped signals.

In a further embodiment, the Pulse generator a circuit for variable setting of the conditions from pulse duration to pulse interval. Through such a circuit it becomes possible that within the pulse frequency, which in turn can be fixed, the ratio between Pulse duration and pulse interval can be set as desired.

The with regard to the two circuits mentioned described setting of the pulse duration and / or the pulse interval can for example about a or several potentiometers. Potentiometers are in themselves known from the prior art. These are adjustable electrical resistors, which have, for example, a sliding contact for tapping part resistors.

Potentiometers can be used, for example, as sliding resistors, rotary resistors, digital Potentiometer or the like can be formed.

In a further embodiment, the Pulse generator a counter module have with a circuit for calibrating the pulse duration connected is. With the help of such a counter module and a like The corresponding circuit described above can provide the required pulse-shaped signals be generated. The counter module can for example about have a so-called "clock input" via the the outgoing signals from the circuit in the counter module be fed. With counter modules, which are known per se from the prior art generally about sequential circuits for counting pulses.

In an advantageous embodiment can the pulse generator one or both of the aforementioned Have circuits. In the latter case, it becomes possible to use pulse-shaped signals set with any pulse duration and pulse interval to be able to. When using two circuits, the pulse generator can be advantageous a switch element for switching between the two Have circuits. The invention is not limited to this Switch element types limited. For example, the switch element as a transistor circuit or the like.

According to the second aspect of the invention, a fuel cell system is provided, with at least one fuel cell, the fuel cell having an anode-electrolyte-cathode unit and an anode catalyst, and with ei ner circuit arrangement for generating voltage pulses and for impressing the voltage pulses on the fuel cell. This fuel cell system is characterized according to the invention in that the circuit arrangement has at least one switch element which is opened and closed to generate the voltage pulses and that the circuit arrangement has at least one capacitance over which the voltage pulses are generated, by means of which electrochemically oxidizable substances are oxidized on the anode or are oxidizable.

In this embodiment, first, for example, via a suitable voltage source, the capacity charged. If the switch element by means of the embossed pulsed Signals is closed, flows a very big one Electricity if during the pulse's capacity and the fuel cell (s) is / are connected in series and thereby the Tension increased becomes. This results in a quick and complete detoxification of the fuel cell (s).

After the pulse process has ended can the capacity over a suitable voltage source can be recharged, as in the further course the description explained more becomes. The capacity between two pulse processes is preferably restored charged.

The invention is not limited to one certain number of capacitors or certain types of capacitors limited. The capacity can preferably be designed as an ultracapacitor. such Capacitors which are known per se from the prior art, feature in addition to high capacity also about a high charge density. They are therefore suitable within a short time Times great Saving or giving away energy. Ultracapacitors are frequently also referred to as supercapacitors or double layer capacitors and are available in terms of their energy density and access time the energy content between large Aluminum electrolytic capacitors and smaller accumulators.

It is also conceivable to use capacitors with changeable capacity to use. Such capacitors have the advantage that the Pulse emitted voltages and thus the fuel cell (s) flowing through streams the prevailing operating conditions and requirements specifically adapted can be.

The present invention is not limited to certain types of fuel cells.

Preferably, the present invention used in connection with fuel cells with polymer membranes (PEM) become. These fuel cells have a high electrical efficiency, cause only minimal emissions, show optimal part-load behavior on and are essentially free of mechanical wear. Another Advantage of PEM fuel cells is their low operating temperature of 80 ° C. Of course you can the invention also in connection with other types of fuel cells are used, for example DMFC fuel cells (Direct Methanol Fuel Cell), SOFC (Solid Oxide Fuel Cell) and the like.

The circuit arrangement according to the second can be advantageous Aspect of the present invention a pulse generator for generating of changeable pulsed Have signals, the at least one switch element for Generation of voltage pulses over the pulse-shaped Signals open and is closed. On the advantageous embodiment and the Operation of the pulse generator is based on the above versions in connection with the first aspect of the invention in full Referenced and hereby referred.

More can be advantageous in the fuel cell system be provided as a fuel cell. Here is the invention not to a certain number or arrangement of fuel cells limited. For example, it is conceivable that in the fuel cell system there are several individual fuel cells. Furthermore, that can Fuel cell system, for example one or more fuel cell modules each with one or more fuel cells. such Fuel cell modules are commonly used referred to as a fuel cell stack. Of course also any combination between single fuel cell (s) and Fuel cell module (s) conceivable.

Those of the circuit arrangement can advantageously be via the pulsed Signals generated voltage pulses on each fuel cell module, respectively any fuel cell regardless of other fuel cell modules, or fuel cells, imprinted become or stampable his. Such a configuration of the fuel cell system leads to a whole range of advantages. If the voltage poles on the fuel cell (s) imprinted be leads this does increase the potential, for example the anode potential, within the Fuel cell, but also to reduce the fuel cell clamping voltage. If now all fuel cells of the fuel cell system at the same time If voltage pulses were applied, this could occur for a short time total loss of the fuel cell system. If fuel cells to drive electrical consumers, for example used to drive electric motors in an automobile, would be a such, even if only briefly, total failure of the fuel cell system, or even a brief, significant loss in performance of the fuel cell system in certain circumstances disadvantageous.

If the individual fuel cells or fuel cell modules are now subjected to voltage pulses independently of one another be, this leads to the fact that such short-term total failures occur only in a small part of the fuel cell system, so that the performance losses of the entire system can be kept to a minimum.

Furthermore, trained in such a way Fuel cell system always such fuel cell modules that voltage pulses are not currently being used are used to generate electrical energy to generate voltage pulses for such To provide fuel cell modules or fuel cells to which appropriate voltage pulses for detoxification are applied should.

Preferably, the Fuel cell (s) over the at least one switch element is short-circuited or short-circuited his. By shorting the Fuel cell (s) flow in it a high current, which in particular the anode potential of the fuel cell (s) shifts in such a way that the the catalyst places blocking harmful Components, for example carbon monoxide or the like, by means of Oxidation can be removed. If the fuel cell (s) are detoxified in such a way should / should, it is advantageous if in the fuel cell system A larger number of fuel cells is present, for example more than ten Fuel cells leading to one or more fuel cell stack summarized are.

In a further embodiment, in the circuit arrangement is provided at least one voltage source his. In this embodiment, will the fuel cell (s) over while the voltage source the pulse (stamping of the voltage pulses) actively short-circuited.

The voltage source can be for example an accumulator, a battery, for example a vehicle battery, a fuel cell, or any other Act voltage source.

If the switch element by means of the pulse-shaped Signals is closed, flows a very big one Current when voltage source (s) and fuel cell (s) are connected in series are and thereby the tension is increased. This causes one fast and complete Detoxification of the fuel cell (s). When using such a Voltage source, it is advantageous if in the fuel cell system only a small number of fuel cells, advantageously fewer than ten fuel cells, especially just one fuel cell is available.

A voltage source can preferably be provided be designed to reload the at least one capacitance is. In this embodiment first, for example about the corresponding voltage source, the capacity loaded. During the Pulsing becomes the capacity then over discharge the fuel cell (s), causing them to operate as previously described advantageous effect is / are short-circuited. The voltage source can again in the manner described above. The capacity between two pulse processes recharged from the voltage source.

Preferably in the circuit arrangement two or more switch elements may be provided. The Switch elements advantageously independently of one another with pulse-shaped signals be charged. It is particularly advantageous if the switch elements be switched in push-pull or are switchable. That way the circuit arrangement continuously between two states and be switched on.

The circuit arrangement can advantageously be a have first mesh in which the at least one capacity, the at least interconnected a fuel cell and a first switch element are.

In a further embodiment, the Circuit arrangement have a second mesh in which the at least a capacity the voltage source and the second switch element are connected.

about the switching of the switch elements can either for the at least one capacitance a charging circuit or an discharging circuit is generated. In this way can switch the circuit arrangement between two states back and forth become. In the first state (charging circuit) the capacity is over Power source charged. In the second state (discharge circuit) the switch elements switched such that the fuel cell over the Capacity shorted becomes. This creates a very high current, leading to detoxification the fuel cell (s) leads, in the harmful Components, such as carbon monoxide or the like, which are on the Catalyst are located, are removed by oxidation.

Preferably at least a switch element designed as a transistor and / or as an IGCT his. Transistors can be over the voltage pulses in a particularly simple way between a conductive State (closed switch) and a blocking state (open switch) switch back and forth. The transistors are preferably MOSFET transistors, IGBT's (Isolated Gate bipolar transistor) or the like. At a IGCT is an “Integrated Gate Commutated Turn-Often Tyristor ".

In a further embodiment, the fuel cell (s) can also be connected in a consumer circuit with at least one consumer. The consumer is the component that is operated with the fuel cell. For example, the consumer can be designed as an electrical drive for a vehicle (electric motor), as an electrical component in a vehicle or the like. Electrical components are, for example, pumps, radios, electrical Window regulators and the like. Of course, the consumer can also be trained in any other way. The invention is also not restricted to the use of fuel cells in vehicles.

In addition, in the consumer group another switch element may be provided. This can, for example be designed as described above. The additional Switch element is preferably switched such that it is open, if the switch element in the circuit arrangement over the pulsed Signals is closed.

Basically, with the present Invention any form of substances from the catalyst of a fuel cell are removed, which can be oxidized in an electrochemical manner. Therefore, the invention is not limited to certain substances. following some become non-exclusive examples for Substances described using the fuel cell system according to the invention can be removed from the anode catalyst of a fuel cell.

Can advantageously be by means of the circuit arrangement for generating voltage pulses and for impressing the voltage pulses the fuel cell as an electrochemically oxidizable substance carbon monoxide be oxidized or be oxidizable.

In a further embodiment, means the circuit arrangement for generating voltage pulses and impress of the voltage pulses on the fuel cell as electrochemically oxidizable Substances containing sulfur and / or compounds are oxidized or be oxidizable.

In a further embodiment, it is also possible, that by means of the circuit arrangement for generating voltage pulses and Imprinting the Voltage pulses on the fuel cell as electrochemically oxidizable Substances containing nitrogen, for example ammonia or the like, and / or Compounds can be oxidized.

Means for tempering can also be advantageous at least individual components of the circuit arrangement are provided his. Depending on the component and operating state of the fuel cell system it may be necessary to at least individual components of the circuit arrangement to warm up or to cool. This can be done over accordingly designed means for tempering can be realized, the Invention is not limited to certain means. Basically is any kind of cooling device or heating device possible. To the constructive Effort and the energy consumption of the fuel cell system so as low as possible can keep the means for tempering preferably components for operation be the fuel cell or use such components. This should be illustrated using two non-exclusive examples become. For example, it is possible at least individual components of the circuit arrangement via a cooling device to cool the fuel cell. If the components of the circuit arrangement are heated, for example should, this can be advantageous the waste heat the fuel cell can be realized. Switching between Warming and cooling or the regulation of the individual temperature control processes with the help of an intelligent control (control device). Decreed for this purpose the intelligent control advantageous through suitable program resources or software.

In a further embodiment, a Control device for controlling at least individual components of the Circuit arrangement and / or for regulating the at least one fuel cell and / or for regulating the means for tempering. The control device is advantageously a type Control device, which is particularly preferred as a central control device of the fuel cell system can be formed. Such a control device has advantageous over at least one computer unit in which suitable program means or Software are stored in order to carry out the individual control steps and / or to monitor.

The control device can be advantageous for regulating pulse parameters of the pulse-shaped signals generated in the pulse generator be trained. Over a such regulation, which in turn is preferably carried out intelligently, can Pulse parameters, in particular pulse width, pulse frequency, pulse amplitude, Pulse duration and the like varies and depends on the corresponding requirements and operating states the fuel cell system can be adjusted and adjusted.

One can advantageously be as above described fuel cell system in or for a vehicle be used. Because of the rapid development of fuel cell technology In the vehicle sector, such use currently offers the greatest possible uses. However, other possible uses are also conceivable. To call here are, for example, fuel cells for mobile devices such as computers, Mobile phones, electrical devices and the like up to power plants. Here is the Fuel cell technology especially for decentralized energy supply of houses, Industrial plants or the like.

The invention will now be exemplified based on exemplary embodiments explained in more detail with reference to the accompanying drawing. Show it:

1 in schematic form a first embodiment of the fuel cell system according to the invention;

2 in schematic form a second embodiment of the fuel cell system according to the invention; and

3 in schematic form, a third embodiment of the fuel cell according to the invention cell system.

Identical components in all embodiments are provided with identical reference numbers.

The fuel cell system 10 according to 1 initially has at least one fuel cell 11 on. Here, the fuel cell system 10 either one or more fuel cells 11 , for example, have a fuel cell stack. In the embodiment according to 1 are advantageous multiple fuel cells 11 , preferably more than ten fuel cells 11 provided, but for the sake of clarity, however, only a single fuel cell 11 is shown. The fuel cells 11 are in a consumer group 30 with at least one consumer 31 connected. The consumer 31 can be any electrical consumer. Still in the consumer circle 30 another switch element 32 provided, for example a transistor.

The fuel cell system 10 also has a circuit arrangement 20 for generating pulse-shaped signals 21 and for impressing over the pulse-shaped signals 21 generated voltage pulses on the fuel cell (s) 11 on. In the circuit arrangement 20 is a switch element 22 provided that over the pulse-shaped signals 21 is opened and closed. In the present case, it is the switch element 22 a transistor, such as an IGBT or the like.

The pulse-shaped signals 21 are from a pulse generator 40 generated. Here is the pulse generator 40 designed such that pulse-shaped signals 21 can be generated with variable parameters. This makes it possible to adapt the pulse parameters to the prevailing, but also to the changing requirements and operating states of the fuel cell system 10 adapt.

It is also in the fuel cell system 10 a control device 50 provided about the individual components of the fuel cell system 10 can be regulated. In the present embodiment, the control device 50 via appropriate control lines 51 . 52 . 53 . 54 . 55 , which are shown in dashed form, with the switch element 22 , the pulse generator 40 , the fuel cell (s) 11 , the switch element 32 as well as with funds 60 for tempering individual components of the circuit arrangement 20 connected.

About the means 60 Individual components of the circuit arrangement can be used for tempering 20 be warmed or cooled. In the embodiment according to 1 the cooling or heating takes place via appropriate cooling or heating circuits for the fuel cell (s) 11 so that the means 60 for tempering in a suitable manner with the fuel cell (s) 11 are connected. For example, it is conceivable that cooling of individual components of the circuit arrangement 20 via a cooling device (not shown) for the fuel cell (s) 11 he follows. For heating individual components of the circuit arrangement 20 can advantageously be the during the operation of the fuel cell (s) 11 waste heat generated in this can be used. In the present embodiment, the means 60 for temperature control via appropriate temperature control lines 61 . 62 with the switch element 22 as well as the pulse generator 40 connected so that these components can be cooled or heated in a suitable manner. Of course, the means 60 for tempering with any other component of the circuit arrangement 20 be connected. The temperature control lines 61 . 62 are shown in the present embodiment in the form of dash-dotted lines.

The functioning of the fuel cell system is now described below 10 described. If the switch element 22 is open, i.e. the transistor blocks or is not conductive, the fuel cell (s) can 11 be poisoned during operation, for example by carbon monoxide-containing fuel, in that the carbon monoxide is free in the anode catalyst of the fuel cell (s) 11 accumulates and blocks these free spaces. In order to be able to remove the harmful carbon monoxide from the anode catalyst by oxidation, which also detoxifies the fuel cell (s) 11 the anode (s) of the fuel cell (s) 11 Voltage pulses are impressed so that the anode potential is shifted to a certain value at which oxidation of the carbon monoxide can take place.

In the embodiment according to 1 this becomes the switch element 22 closed. That means the transistor 22 about the pulsed signals 21 is switched on. As a result, the fuel cell (s) 11 temporarily short-circuited. The short circuit can remove the carbon monoxide deposits from the anode catalyst.

The optional switch element 32 in the consumer circle 30 can be switched so that this during the period in which the switch element 22 is closed (the transistor is conductive), is open.

In 2 is another embodiment of a fuel cell system 10 shown. The fuel cell system 10 shows a basic structure like that 1 on, so that to avoid repetition at this point 1 is referred. In addition, in the circuit arrangement 20 another voltage source 24 provided, which can be designed for example as a car battery, accumulator, fuel cell and the like. The voltage source 24 is such in the circuit arrangement 20 arranged that they with respect to the fuel cell 11 polarity is opposite. The voltage source 24 can via a suitable control line 56 with the control device 50 be connected.

During the operation of the fuel cell system 10 can be used for the purpose of detoxifying the fuel cell 11 first the switch element again 22 getting closed. This is done in that the switch element designed as a transistor 22 about the pulsed signals 21 is turned on first. This will be the voltage source 24 and the fuel cell 11 connected in series, which increases the voltage and causes a very large current to flow, which detoxifies the fuel cell in the manner described above 11 causes.

With such a configuration of the fuel cell system 10 are preferably very few fuel cells 11 provided, preferably less than ten fuel cells, very particularly preferably only one fuel cell 11 ,

In 3 is finally another embodiment of a fuel cell system 10 shown. The fuel cell system 10 again has one or more fuel cell (s) 11 on. Furthermore, there is a circuit arrangement 20 provided, generated via the voltage pulses and applied to the fuel cell (s) 11 can be imprinted. The circuit arrangement 20 has two switch elements 22 . 23 in the form of transistors. Furthermore are in the circuit arrangement 20 a pulse generator 40 , Medium 60 for tempering and a control device 50 provided, for their structure and basic functionality on the above statements on the embodiments according to 1 and 2 will refer.

The circuit arrangement 20 has a first stitch 25 on at least one capacity 27 , for example a so-called ultracapacitor, the fuel cell (s) 11 and a first switch element 22 are connected. All of these components are on appropriate control lines 58 . 53 . 51 with the control device 50 connected. Furthermore, the circuit arrangement has 20 a second stitch 26 on in which the at least one capacity 27 , a voltage source 28 such as one related to 2 described voltage source, and the second switch element 23 are connected. The voltage source 28 as well as the switch element 23 are also on control lines 57 . 59 with the control device 50 connected. So are the means 60 for tempering and the pulse generator 40 via control lines 54 . 52 with the control device 50 connected.

Both switch elements 22 . 23 can on the pulse-shaped signals 21 can be switched independently. The circuit of the switch elements sees 22 . 23 before that the two stitches 25 . 26 either as a charging circuit or as an unloading circuit for the capacity 27 act.

The functioning of the fuel cell system is now described below 10 according to 3 described.

In the first state of the circuit arrangement 20 is the switch element 22 opened and the switch element 23 closed (transistor 22 locks and transistor 23 is switched on). The capacity 27 is about the voltage source 28 loaded.

In the second state of the circuit arrangement 20 becomes the fuel cell 11 shorted by the switch element 22 closed (transistor 22 is conductive) and the switch element 23 open (transistor 23 is blocked). The "+" pole of the capacitance is advantageous 27 with the "-" pole of the fuel cell 11 connected. The "-" pole of capacity 27 is with the "+" pole of the fuel cell 11 connected. As a result, flows through the fuel cell 11 a very high current, which detoxifies the fuel cell in the manner already described above 11 causes.

About the pulsed signals 21 become the switch elements 22 . 23 advantageously switched in "push-pull" mode in order to alternate the two previously described states of the circuit arrangement 20 to reach.

10

The fuel cell system

11

fuel cell

20

switch arrangement for creating and stamping of voltage pulses

21

pulse-shaped signal

22

switching element (Transistor)

23

switching element (Transistor)

24

voltage source

25

first mesh

26

second mesh

27

capacity

28

voltage source

30

consumer circuit

31

consumer

32

switching element

40

pulse generator

50

control device

51

control line

52

control line

53

control line

54

control line

55

control line

56

control line

57

control line

58

control line

59

control line

60

medium for tempering

61

temperature control line

62

temperature control line

Claims (21)

Fuel cell system, with at least one Fuel cell ( 11 ), the fuel cell ( 11 ) has an anode-electrolyte-cathode unit and an anode catalyst, and with a circuit arrangement ( 20 ) for generating voltage pulses and for impressing the voltage pulses on the fuel cell ( 11 ), characterized in that the circuit arrangement ( 20 ) a pulse generator ( 40 ) for generating variable pulse-shaped signals ( 21 ) has that the circuit arrangement ( 20 ) at least one switch element ( 22 . 23 ) which is characterized by the pulse-shaped signals ( 21 ) is opened and closed and that the pulse-shaped signals ( 21 ) Voltage pulses are generated, by means of which electrochemically oxidizable substances are oxidized or can be oxidized on the anode. Fuel cell system, with at least one fuel cell ( 11 ), the fuel cell ( 11 ) has an anode-electrolyte-cathode unit and an anode catalyst, and with a circuit arrangement ( 20 ) for generating voltage pulses and for impressing the voltage pulses on the fuel cell ( 11 ), characterized in that the circuit arrangement ( 20 ) at least one switch element ( 22 . 23 ) that is opened and closed to generate the voltage pulses and that the circuit arrangement ( 20 ) at least one capacity ( 27 ), via which the voltage pulses are generated, by means of which electrochemically oxidizable substances are oxidized or can be oxidized on the anode. Fuel cell system according to claim 2, characterized in that the circuit arrangement ( 20 ) a pulse generator ( 40 ) for generating variable pulse-shaped signals ( 21 ) and that the switch element ( 22 . 23 ) to generate voltage pulses via the pulse-shaped signals ( 21 ) is opened and closed. Fuel cell system according to one of Claims 1 to 3, characterized in that more than one fuel cell ( 11 ) is provided. Fuel cell system according to one of claims 1 to 4, characterized in that the fuel cell (s) ( 11 ) via the at least one switch element ( 22 . 23 ) is short-circuited or can be short-circuited. Fuel cell system according to one of claims 1 to 5, characterized in that in the circuit arrangement ( 20 ) at least one voltage source ( 24 ; 28 ) is provided. Fuel cell system according to Claim 6, insofar as it relates to one of Claims 2 to 5, characterized in that the at least one voltage source ( 28 ) for reloading the at least one capacity ( 27 ) is trained. Fuel cell system according to one of claims 1 to 7, characterized in that in the circuit arrangement ( 20 ) two or more switch elements ( 22 . 23 ) are provided. Fuel cell system according to claim 8, characterized in that the switch elements ( 22 . 23 ) independently of one another with pulse-shaped signals ( 21 ) can be or can be applied. Fuel cell system according to claim 8 or 9, characterized in that the switch elements ( 22 . 23 ) can be switched in push-pull mode or can be switched. Fuel cell system according to one of claims 2 to 10, characterized in that the circuit arrangement ( 20 ) a first stitch ( 25 ) in which the at least one capacitance ( 27 ) that have at least one fuel cell ( 11 ) and a first switch element ( 22 ) are connected. Fuel cell system according to one of claims 2 to 11, characterized in that the circuit arrangement ( 20 ) a second stitch ( 26 ) in which the at least one capacitance ( 27 ), a voltage source ( 28 ) and a second switch element ( 23 ) are connected. Fuel cell system according to one of Claims 8 to 12, characterized in that the switching elements ( 22 . 23 ) a charging circuit or an discharging circuit for the at least one capacity ( 27 ) is produced. Fuel cell system according to one of claims 1 to 13, characterized in that the at least one switch element ( 22 . 23 ) is designed as a transistor and / or as an IGCT. Fuel cell system according to one of claims 1 to 14, characterized in that the fuel cell (s) ( 11 ) still in a consumer group ( 30 ) with at least one consumer ( 31 ) is / are switched. Fuel cell system according to one of claims 1 to 15, characterized in that by means of the circuit arrangement ( 20 ) for generating voltage pulses and for impressing the voltage pulses on the fuel cell ( 11 ) carbon monoxide is oxidized as an electrochemically oxidizable substance or is oxidizable. Fuel cell system according to one of claims 1 to 16, characterized in that by means of the circuit arrangement ( 20 ) for generating voltage pulses and for impressing the voltage pulses on the fuel cell ( 11 ) as electro chemically oxidizable substances, sulfur-containing substances and / or compounds are oxidized or are oxidizable. Fuel cell system according to one of claims 1 to 17, characterized in that by means of the circuit arrangement ( 20 ) for generating voltage pulses and for impressing the voltage pulses on the fuel cell ( 11 ) nitrogen-containing substances and / or compounds are oxidized or are oxidizable as electrochemically oxidizable substances. Fuel cell system according to one of claims 1 to 18, characterized in that means ( 60 ) for tempering at least individual components of the circuit arrangement ( 20 ) are provided. Fuel cell system according to one of claims 1 to 19, characterized in that a control device ( 50 ) for regulating at least individual components of the circuit arrangement ( 20 ) and / or for regulating the at least one fuel cell ( 11 ) and / or to regulate the means ( 60 ) is provided for tempering. Fuel cell system according to claim 20, characterized in that the control device ( 50 ) for controlling pulse parameters in the pulse generator ( 40 ) generated pulse-shaped signals ( 21 ) is trained.