DE102015225117A1 - Method, means of locomotion and electronic control unit for monitoring an operation of a fuel cell of a means of locomotion - Google Patents

Abstract

An electronic control unit, a means of locomotion as well as a method for impedance spectroscopy of a fuel cell (1) of a means of locomotion (10) are proposed. The method comprises the steps:
Determining a need to examine the fuel cell (1) by means of impedance spectroscopy with respect to a predefined property,
Determining changes in a predefined operating state of an electrical component of the means of locomotion (10),
- Determining that the changed operating state of the electrical component (2) has a suitable load state for the fuel cell (1) for determining the predefined property, and
- Recording a characteristic of the impedance of the fuel cell (1) characteristic over time based on the load condition.

Description

The present invention relates to a method, a means of locomotion and an electronic control unit for monitoring an operation of a fuel cell of a means of locomotion. In particular, the present invention relates to a resource-conserving evaluation of the state of a fuel cell by means of impedance spectroscopy.

Fuel cells are designed due to their design (series connection of individual voltage sources) to a certain voltage level. Electric powertrains in vehicles contain additional voltage sources with varying voltage levels depending on the load point. The provided electrical power is fed into a bus system, from which supply several consumers. For this purpose, a voltage converter between the fuel cell and the electric bus is switched. This voltage converter can be actively used to examine the fuel cell for its current operating state and / or for damage. Here, an additional frequency is impressed on the load signal and evaluated the voltage response of the system in the frequency domain (also known as "impedance spectroscopy"). Individual consumers, the operating strategy, environmental influences or defective / defective components can lead to additional, high-frequency excitations, which can lead to reversible or even irreversible damage to the electrochemically active layers. The fuel cell according to the prior art, due to their media supply, the operating history and unevenness of the reactive distribution their electrical property greatly (especially disadvantageous) change. An active impedance spectroscopy, however, requires a defined excitation, the z. B. by Fast Fourier Transformation (FFT) and can not be available in all operating conditions. In addition, a Fast Fourier Transformation for the computing power available in current on-board vehicle networks, despite their reduced instructions, is a computationally expensive process by which other processes in the informational network can be compromised. Moreover, although information about changes in performance according to the prior art is recorded, it does not capture the cause of the damage.

It is an object of the present invention to overcome the disadvantages known from the prior art.

The object identified above is achieved according to the invention by a method for impedance spectroscopy of a fuel cell of a means of locomotion. The means of transport may be, for example, a car, a van, a truck, a motorcycle, an aircraft and / or watercraft. In a first step, a need for examining the fuel cell by means of impedance spectroscopy with respect to at least one predefined characteristic (eg a predefined frequency range, an amplitude, a measurement duration and a fuel cell operating point) is determined. Subsequently, changes in a predefined operating state of an electrical component or an electrical load (eg, an ohmic resistance, an on-board network component having an effect on the vehicle electrical system voltage or the like) of the means of locomotion are determined. In a further step, it is determined that the changed operating state of the electrical component has a suitable load state for the fuel cell for determining the predefined properties by means of impedance spectroscopy. In other words, the behavior of the electrical load is recognized to the effect that the load state, an active additional excitation to determine the system response of the fuel cell is unnecessary or at least advantageously supplemented. Finally, a characteristic describing the impedance of the fuel cell may be recorded over time on the basis of the load condition recognized as being suitable. According to the invention, the recording can be carried out separately from an analysis of the impedance of the fuel cell. This is advantageous, in particular, for the reason that the recording requires considerably less computing power than would be the result of a simultaneous or immediate analysis (eg by means of an FFT). In addition, the use of a suitable load state of the electrical component makes it unnecessary to provide and / or generate identical or at least similar excitation signals. This saves memory and hardware for signal generation.

The dependent claims show preferred developments of the invention.

Optionally, an improvement potential with regard to a suitability of the load state for determining the predefined property can be recognized and, in response thereto, an operating state of the electrical component can be adapted to improve the property. For example. For example, a power consumption of the component for increasing an amplitude of the reaction to the fuel cell can be increased. Alternatively or additionally, a frequency and / or a time behavior (eg a signal shape) of the power consumption of the electrical component can be adapted in order to achieve a more suitable excitation of the fuel cell. For example. Such a power consumption can not take place by means of components that are not immediately tangible to the user of the means of transportation. For example. can a Rear window heater record a comparatively large electrical power, which, however, brings no loss of comfort for the user with it. The same applies to seat heaters on seat positions, which are currently unoccupied (which can be detected, for example, via a seat occupancy sensor).

Alternatively or additionally, a second electrical component for improving a suitability of the load state for determining the predefined property or a second predefined property of the fuel cell can be switched on. In other words, by superposing the power consumption of the first electrical component and the second electrical component, a suitable excitation or reaction to the fuel cell can be generated. If a specific frequency profile is to be generated, the ratios of the power consumptions between the first component and the second component can also be varied over time in a continuous and / or stepped manner (eg abruptly).

In order to prevent an effect of the recorded impedance profiles of the fuel cell over time from becoming a problem for foreign processes to be executed by the same arithmetic unit, it can be determined in a further step that there is a reduced need for computing power in an evaluation unit provided for evaluating the impedance spectroscopy. This can be done, for example, in a moment in which a previously running (eg, computation-intensive) process is ended. In response thereto, an evaluation of the recorded, the impedance of the fuel cell descriptive characteristic over time can be triggered by means of the evaluation. For example. Thus, it can be recognized that the utilization of the evaluation unit has dropped, and in response thereto, the evaluation of the fuel cell impedances recorded according to the invention is started automatically. In particular, a result of the evaluation can be stored in a data memory and results of evaluations for use in and after the operation of the system can be kept ready. The results may, for example, characterize the operating state in which the impedance spectrum was recorded. For example. In a service workshop, a comparison between different Impendanzspektren be made, which were taken in conjunction with a defective component. The component may, for example, be a windshield wiper. Also during operation of the means of locomotion specific operating points and / or time intervals can be detected or filtered. If it has been found that a specific operating point for impedance spectroscopy is particularly suitable, at least with regard to a predefined characteristic, information can be stored in a data memory as to what conditions this operating point has occurred or is likely to occur again. Due to current operating conditions and / or time information, it can be recognized at a later time that the suitable operating point will readily re-establish itself and give opportunity for impedance spectroscopy with respect to the predefined property. As a result, a specially provided for this purpose excitation of the fuel cell can be omitted, whereby energy can be saved.

In a method according to the invention, it is also preferably possible to determine a need for the investigation of the fuel cell by means of an impedance spectroscopy with respect to a predefined second property different from the first property. In response to the determination of this need, a second impedance spectroscopy process according to the invention can be initiated, which will occur in any case during operation of the fuel cell due to the expected operating behavior of the means of locomotion. For this purpose, for example, an estimate with respect to the future behavior of the fuel cell can be determined. Such information may be derived, for example, time-based and / or in response to the achievement of a predefined geographical position or the like. For this purpose, a documentation of a course of the change of the operating state over the operating period can be made so that at a future time an initial course of the change of the operating state can be detected and closed on the further course. On the basis of such information, operating states can be predicted which are suitable for the use according to the invention in the operation of load states which occur in any case for impedance spectroscopy.

The recording of the operating states here is not limited to an electrical load behavior of a respective component. Rather, information that allows a prediction and / or an interpretation of a current operating state better, for. B. be read from an on-board computer.

Preferably, it can also be recognized that a current operating state of an electrical system of the means of locomotion prevents a meaningful evaluation of the recorded parameter describing the impedance of the fuel cell, and in response the recording is discarded before its evaluation. For example. it can be determined that a third consumer in addition to the first and second (each in principle for impedance spectroscopy classified as suitable) consumers are operated in parallel to a third consumer, which causes a total load which defeats impedance spectroscopy. In other words, exclusion criteria for a durable record of fuel cell impedance may be defined in response to the occurrence of discarding the recordings without performing an evaluation (eg, an FFT) on that data. This avoids unnecessary computational effort for such evaluations about which it is known that no meaningful results are to be expected.

Preferably, a parameter describing the impedance of the fuel cell can be evaluated by a transformation of the characteristic from the time domain into the frequency domain. Such a transformation can take place comparatively resource-conserving by means of an FFT.

As is known, recording high-frequency oscillation components is only possible with a high sampling rate (Nyquist criterion), so that large amounts of data must be stored when recording and storing high-frequency oscillation components. Therefore, the provision of such data for subsequent evaluation is at least not attractive if a current utilization of a processor to be used for the evaluation requires a longer-term storage of the data.

Since due to the possibility of an active imposition of defined oscillations (load states), evaluation routines in the frequency domain can already be implemented on the voltage converter, these can also be used without a predefined excitation intended specifically for impedance spectroscopy.

A regular and / or event-controlled passive evaluation of the frequency range is also proposed as an option in order to transfer data transformed into the frequency domain via the general operation and / or defined operating states. B. store in the form of rainflow tables or histograms and to be able to maintain their change over time in a compressed form. The data set stored in this way can be used for further functions, which are eg. As the reliability, the operating strategy, the service and / or the design of future systems are used.

According to a second aspect of the present invention, there is proposed an electronic control apparatus for monitoring an operation of a fuel cell of a vehicle. The electronic control unit comprises a memory means, a signal input, a signal output and an evaluation unit. This is set up by means of the storage means to determine a need to examine the fuel cell by means of impedance spectroscopy with respect to a predefined property. The predefined property can, for example, identify a predefined frequency range for a predefined signal shape and / or predefined signal amplitude. Furthermore, the evaluation unit is set up to determine an operating state of an electrical component of the means of locomotion. By means of the signal input, the evaluation unit can determine that the operating state of the electrical component has a suitable load state for the fuel cell for determining the predefined characteristic. By means of the signal output, the evaluation unit can record a parameter describing the impedance of the fuel cell over time on the basis of the load condition. In this way, so to speak, a time signal is stored without immediately evaluating it by means of an impedance spectroscopy. However, this evaluation is prepared by the determination and storage according to the invention and can take place at such a time in which sufficient computational resources are available.

In other words, the electronic control unit according to the invention is set up to realize the features, feature combinations and the resulting advantages of the method according to the invention in a corresponding manner, so reference is made to avoid repetition of the above statements.

According to a third aspect of the present invention, a means of transportation is proposed, which can be designed as a car, van, truck, motorcycle, aircraft and / or watercraft. The means of transportation comprises a fuel cell or is at least adapted for use with a fuel cell. Further, there is provided an electronic control apparatus according to the second aspect of the present invention, by which the traveling means realizes the same features, feature combinations and advantages.

The advantages of the present aspects of the invention are, in particular, the reduction of a data volume to be kept, which can be used, for example, in prototype vehicles for the analysis of stresses for traction of fuel cells used. In addition, the troubleshooting in the development and in the case of service in series vehicles simplifies. In addition, improvements in the understanding of the system interactions in the system network result in real driving situations and thus a potential for system optimization.

Further details, features and advantages of the invention will become apparent from the following description and the figures. Show it:

1 a schematic view of components of an embodiment of an electronic control device according to the invention in an embodiment of a means of transport according to the invention;

2 a schematic sketch of known in the art arrangements for impedance spectroscopy;

3 a schematic view of an inventively designed electronic control unit in the system network with a fuel cell and a means of locomotion; and

4 a flowchart, illustrating steps of an embodiment of an inventive method for impedance spectroscopy of a fuel cell of a means of transport.

1 shows a car 10 as an embodiment of a means of transport according to the invention, which by means of an electric machine 13 is drivable. An electronic control unit 4 is as an example of an evaluation unit for impedance spectroscopy information technology and energetic with the electric machine 13 , two consumers 2 . 3 and a fuel cell 1 connected. Another electronic control unit 11 is information technology with the electronic control unit 4 connected. It has a processor 6 as an evaluation unit, which via a signal input 8th as well as two signal outputs 7 . 9 features. The signal input 8th is information technology with the electronic control unit 4 connected. The signal output 7 is information technology with a screen 12 for outputting data obtained by means of impedance spectroscopy. The signal output 9 is information technology with a data memory 5 connected as storage means. Details about and how the in 1 The arrangement shown will be described in more detail in connection with the following figures.

2 shows components of an arrangement, as in the prior art for impedance spectroscopy of a fuel cell 1 in a car 10 is used. The car has an electric machine 13 and electrical sensors 20 for the determination of current, voltage and power within the vehicle electrical system. The electric machine 13 is via an electrical connection 22 with an actuator 16 the electrical unit 14 the fuel cell 1 connected. The sensors 20 are about an information line 18 with an electronic control unit 6 connected, which the sensor signals to determine operating conditions of the car 10 used. Also the fuel cell 1 has sensors 15 on, by means of which operating states (eg power, current output, voltage, temperature, etc.) of the electrical system 14 determined and via another information line 18 to the evaluation unit 6 to execute an FFT 19 can be sent. Inside the fuel cell 1 are still media 17 via a media line 21 provided, which are required for the operation of the electrical cells. These can, for example, supply the fuel and / or the oxygen. To promote the media 17 in the electrical unit 14 is still an electrical connection 22 intended. The process 6 receives over an information line 18 the ability to influence the operation of the fuel cell 1 to remove and / or information about the operation of the fuel cell 1 read. As is conventional in the art, an FFT is performed 19 always immediately after receipt of appropriate sensor data from the fuel cell 1 in the processor 6 , whereby a storage of the data and their subsequent evaluation are not possible. The information from the fuel cell system is provided by the processor 6 requested, immediately determined and subsequently reported.

3 shows an overview of components of an embodiment of an electronic control device according to the invention 11 in an information network with a fuel cell 1 and a car 10 , The components electric machine 13 , Sensors 20 , electronic control unit 6 and fuel cell 1 are essentially the same 2 designed and interconnected, which is why with reference to these elements, the embodiments in conjunction with 2 Keep validity. However, there is an additional information line 18 between the electronic control unit 11 and the sensors 20 provided and an evaluation of the sensors 15 the fuel cell 1 Determined parameters by the electronic control unit 6 by means of an FFT 19 no longer provided. The electronic control unit 11 has a long-term data memory 5 on, which perceives three different functions. On the one hand, the frequency space of the fuel cell 1 managed and identified a need for measurements. This can be done, for example, by recognizing that information in a certain frequency range is no longer sufficiently current, so that it is to be feared that the state of the fuel cell 1 could have changed. In addition, an active excitation according to the prior art by the long-term data memory 5 allows by this holds a signal generator, with which the impedance spectroscopy of the fuel cell can be carried out in a conventional manner or an impedance spectroscopy according to the invention can be supported. In addition, there is a continuous monitoring of the stored data and an active search for new suggestions in the electrical system, which possibly for the electrical stimulation of Fuel cell could be used in the course of an impedance spectroscopy according to the invention. Last but not least, the long-term data memory keeps 5 a list of currently existing suggestions by the current operation of the electrical system of the means of transport ready. This function can also be understood as administration of the fuel cell frequency space. The long-term data memory 5 Thus, it holds signals for a large number of excitation signals required in the context of conventional impedance spectroscopy, as well as a list of such operating states which can be used in the present vehicle electrical system for impedance spectroscopy or which complicate or even prevent impedance spectroscopy. The consumers can be configured as traction components and / or as secondary consumers. In other words, the long-term data memory 5 Have system knowledge available by which operating conditions of the electrical system according to predefined properties of the fuel cell 1 can be assigned to determine which they are suitable. A trigger module 23 is set up by the long-term data memory 5 to read, manage and control the measuring points. In addition, the trigger module 23 capable of sensor data of the fuel cell 1 as well as the car 10 via data lines 18 to receive and interpret. Environmental data can also be obtained from the trigger module 23 (eg via the sensors 20 ) are received and interpreted. Successfully evaluated records can be generated by the trigger module 23 to the long-term data memory 5 be reported back. The trigger module 23 is thus set up to actively initiate the performance of a measurement, specifically a recording of an impedance behavior of the fuel cell 1 if there is again a need for updated predefined properties of the fuel cell 1 and for this purpose, there are suitable load states for the fuel cell and trigger an FFT of the recorded impedance-time data only when the computing capacities required for this purpose are available.

4 shows steps of an embodiment of an inventive method for impedance spectroscopy of a fuel cell of a means of transport. In step 100 For example, a need to examine the fuel cell by impedance spectroscopy for a predefined property is determined and in step 200 Changes a predefined operating condition of an electrical component of the means of transport determined. If the change of the predefined operating state does not allow a determination of the predefined property, it is possible to wait until in step 300 an improvement potential regarding a suitability of the load state for the determination of the predefined property is detected and in response thereto in step 400 an operating state of the electrical component is adapted to improve the suitability. In step 500 In addition, a second electrical component for improving a suitability of the load state for determining the predefined property is turned on and in step 600 determines that the changed operating state of the electrical component has a suitable load state for the fuel cell to determine the predefined property. In step 700 Finally, a characteristic describing the impedance of the fuel cell is recorded over time on the basis of the load condition without carrying out an evaluation (in the form of an FFT). In step 800 For example, a need to examine the fuel cell by impedance spectroscopy with respect to a predefined second property different from the first property is determined, and in step 900 an estimate of the future behavior of the fuel cell determined. In step 1000 A course of the change of the operating state over the operating time is documented in order to be able to carry out a timely detection of this operating state in the future in the event that the operating state brings about a suitable excitation for determining a predefined characteristic. In step 1100 a reduced demand for computing power is determined in an evaluation unit provided for the evaluation of the impedance spectroscopy and in response thereto an evaluation of the recorded characteristic quantity describing the impedance of the fuel cell over time by means of the evaluation unit in step 1200 initiated. In step 1300 a result of the evaluation is stored in a data memory and in step 1400 the result of evaluations for use in and after the operation of the means of transport. In step 1500 Finally, it is recognized that a current operating state of a vehicle electrical system of the means of transport prevents a meaningful evaluation of the recorded, the impedance of the fuel cell descriptive characteristic, and in response thereto in step 1600 discarded the recording prior to its evaluation (using an FFT). In this way, the evaluation of such impedance-time recordings is avoided, which, according to experience, do not provide any suitable information about predefined properties of the fuel cell.

LIST OF REFERENCE NUMBERS

1

 fuel cell

2, 3

Component (consumer)

4

 electronic control unit

5

 (Long-term) memory data

6

 processor

7

 data output

8th

 data input

9

 data output

10

car

11

electronic control unit

12

screen

13

electric machine

14

electrical unit of the fuel cell

15

Sensors of the fuel cell

16

Actuators of the fuel cell

17

media

18

information lines

19

FFT

20

Sensors of the means of transport

21

media lines

22

electrical connections

23

Trigger module

100

1600

steps

FFT

Fast Fourier Transformation

Claims (10)

Method for impedance spectroscopy of a fuel cell ( 1 ) of a means of transportation ( 10 ) comprising the steps of: - determining ( 100 ) a need for testing the fuel cell ( 1 ) by means of impedance spectroscopy with respect to a predefined property, 200 ) changes of a predefined operating state of an electrical component ( 2 ) of the means of locomotion ( 10 ), - Determine ( 600 ) that the changed operating state of the electrical component ( 2 ) a suitable load state for the fuel cell ( 1 ) for determining the predefined property, and - recording ( 700 ) one the impedance of the fuel cell ( 1 ) descriptive parameter over time based on the load condition. The method of claim 1 further comprising - detecting ( 300 ) of an improvement potential with regard to a suitability of the load state for the determination of the predefined property, and in response thereto - adapting ( 400 ) an operating state of the electrical component ( 2 ) to improve the suitability. Method according to claim 2 further comprising - switching on ( 500 ) a second electrical component ( 2 ) for improving the suitability of the load state for determining the predefined property or a second predefined property of the fuel cell ( 1 ) having. Method according to one of the preceding claims further comprising - determining ( 1100 ) of a reduced need for computing power in an evaluation unit provided for the evaluation of the impedance spectroscopy ( 4 ) and in response - initiate ( 1200 ) an evaluation of the recorded, the impedance of the fuel cell ( 1 ) descriptive parameter over time by means of the evaluation unit ( 4 ) and in particular - filing ( 1300 ) of a result of the evaluation in a data memory and further in particular - keeping ready ( 1400 ) a result of evaluations for use in and after operation of the system. Method according to one of the preceding claims further comprising - determining ( 800 ) a need for testing the fuel cell ( 1 ) by means of impedance spectroscopy with respect to a predefined second property, and / or - determining ( 900 ) an estimation regarding the future behavior of the fuel cell ( 1 ), and / or - documentation ( 1000 ) a course of change of the operating state over the operating time. Method according to one of the preceding claims further comprising - detecting ( 1500 ) that a current operating state of a vehicle electrical system of the means of transport ( 10 ) a meaningful evaluation of the recorded, the impedance of the fuel cell ( 1 ) and, in response, - discarding ( 1600 ) the recording already before its evaluation. Method according to one of the preceding claims further comprising - evaluating the impedance of the fuel cell ( 1 ) descriptive characteristic by a transformation of the characteristic from the time domain in the frequency domain. Electronic control unit ( 11 ) for monitoring an operation of a fuel cell ( 1 ) of a means of transportation ( 10 ) - memory means ( 5 ), - a signal input ( 8th ), - a signal output ( 9 ) and - an evaluation unit ( 6 ), which is set up, - by means of the storage means ( 5 ) a need to study the fuel cell ( 1 ) by means of impedance spectroscopy to determine a predefined property, - an operating state of an electrical component ( 2 ) of the means of locomotion ( 10 ), - by means of the signal input ( 8th ) to determine that the operating state of the electrical component ( 2 ) a suitable load state for the fuel cell ( 1 ) for determining the predefined property, and - by means of the signal output ( 9 ) one the impedance of the fuel cell ( 1 ) descriptive Record characteristic over time based on the load condition.  An electronic control apparatus according to claim 8, arranged to carry out a method according to any one of claims 1 to 7.  Means of transport comprising an electronic control unit according to one of claims 8 or 9.

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