CN115882012A - Method and apparatus for health diagnosis of fuel cell in vehicle environment - Google Patents
Method and apparatus for health diagnosis of fuel cell in vehicle environment Download PDFInfo
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Abstract
The present invention relates to the field of fuel cells. The invention relates to a method for health diagnosis of a fuel cell in a vehicle environment, comprising the following steps: s1: applying a disturbance current to a voltage converter directly connected to the fuel cell, such that an electrical load state switchover in the on-board electrical system is simulated by means of the disturbance current; s2: detecting an output voltage response of the fuel cell; s3: information relating to different loss mechanisms is determined from different segments of the output voltage response of the fuel cell. The invention also relates to an apparatus and a computer program product for health diagnosis of a fuel cell in a vehicle environment. The present invention aims to provide a fuel cell health diagnostic scheme that can be easily implemented in a vehicle environment, is low-cost, and can implement different degradation mechanism analyses.
Description
Technical Field
The present invention relates to a method for health diagnosis of a fuel cell in a vehicle environment, to a device for health diagnosis of a fuel cell in a vehicle environment and to a computer program product.
Background
Fuel cells are widely used in the field of electric vehicles as a clean energy source capable of reducing greenhouse gas emissions. However, lifetime remains a major bottleneck faced by fuel cells. It is of great importance to develop a scheme for diagnosing the state of health (SOH) of a fuel cell.
In the prior art, the most popular diagnostic methods for achieving state of health monitoring of fuel cells are polarization curve measurement and Alternating Current (AC) impedance spectroscopy. However, these two solutions still have a number of disadvantages, in particular, the polarization curve only reflects the overall performance of the fuel cell, and cannot distinguish between different types of losses. The medium-low frequency ac impedance spectroscopy has been used in a laboratory environment for degradation measurement of fuel cells, but is not suitable for conventional vehicle applications due to long measurement time and unstable operating conditions. High frequency ac impedance measurements can separate ohmic resistance induced losses, however, this method still provides insufficient information when the fuel cell is operating under high load and when mass transfer losses dominate.
In this context, it is desirable to provide a fuel cell health diagnostic solution that can be easily implemented in a vehicle environment, is low cost, and can implement different degradation mechanism analyses.
Disclosure of Invention
It is an object of the present invention to provide a method for health diagnosis of a fuel cell in a vehicle environment, an apparatus for health diagnosis of a fuel cell in a vehicle environment and a computer program product to solve at least some of the problems of the prior art.
According to a first aspect of the present invention, there is provided a method for health diagnosis of a fuel cell in a vehicle environment, the method comprising the steps of:
s1: applying a disturbance current to a voltage converter directly connected to the fuel cell, such that an electrical load state switching in the on-board electrical system is simulated by means of the disturbance current;
s2: detecting an output voltage response of the fuel cell; and
s3: information relating to different loss mechanisms is determined from different segments of the output voltage response of the fuel cell.
The invention comprises in particular the following technical concepts: by applying a disturbance current in a specific form to the vehicle-mounted voltage converter, large-span load change from a polarization area to a mass transfer area is simulated for the fuel cell in a vehicle environment, and a specific diagnosis method which can be realized under an experimental condition is transferred to the vehicle environment, so that more effective information about the health state of the fuel cell can be resolved without disassembling the fuel cell and adding complex equipment. Furthermore, this health diagnostic method allows the different wear types of the fuel cell to be distinguished, which is of great significance for exploring the cause of the degradation of the overall performance of the fuel cell.
Alternatively, the voltage converter directly connected to the fuel cell includes a DC/DC converter and a DC/AC converter.
Thereby, the following technical advantages are achieved: therefore, the health diagnosis method can be applied to different types of vehicle power topological structures, and the applicability of the method is improved.
Optionally, simulating electrical load state switching in the on-board electrical network comprises: the switching in or out of at least some, in particular all, electrical loads in the onboard electrical system is simulated.
Thereby, the following technical advantages are achieved: the output current and the output voltage of the fuel cell dynamically change according to the load condition in the vehicle-mounted power grid using the fuel cell as a power source, and under the condition of fluctuating electronic load, a plurality of structural degradations caused by the aging of the battery can be more obviously reflected by the trend of voltage change. By recording these physical quantities which are easy to measure for the vehicle fuel cell model, the degradation information of the fuel cell can be seen more intuitively, and therefore the state of health analysis is achieved at a lower cost as a whole.
Optionally, applying the perturbation current comprises:
increasing the originally applied constant current jump on the voltage converter to a defined value, in particular applying a step current on the voltage converter; alternatively, the first and second electrodes may be,
the constant current jump originally applied to the voltage converter is reduced to a defined value, in particular interrupted.
Thereby, the following technical advantages are achieved: different from the traditional alternating current impedance spectroscopy method in which a small amplitude alternating current ripple signal is superposed near a steady-state working point, the disturbance current introduced in the method can simulate the switching of the load state of the fuel cell, and the current switching-in or removal can realize continuous information feedback from a polarization region to a mass transfer region, so that richer information is provided for the health diagnosis of the fuel cell.
Optionally, the method further comprises the steps of: the cathode reactant gas supply to the fuel cell is stopped before the perturbation current is applied.
Thereby, the following technical advantages are achieved: as the reactant gas is consumed, the cathode reactant concentration reaching the reaction zone becomes smaller and the transport rate decreases. Thus, mass transfer losses at this stage are more pronounced.
Optionally, the step S3 includes:
determining information related to a first loss mechanism from a voltage ramping process over a first time period of an output voltage response; and
information relating to the second loss mechanism and/or the third loss mechanism is determined from a slow voltage change process over a second period of the output voltage response, the second period being after the first period.
Thereby, the following technical advantages are achieved: the actual output voltage of the fuel cell can be represented by the thermodynamically predicted voltage minus various over-voltage losses, including losses due to different degradation mechanisms. These degradation mechanisms can be manifested by different stages of the amount of change in the output voltage of the fuel cell, due to the different laws of electricity followed and the dominant equivalent circuit elements. By such a segmented analysis of the voltage response, an efficient differentiation of the different degradation mechanisms is achieved.
Alternatively, the first period includes a period from when the disturbance current is applied until the disturbance current reaches a steady state, and the second period includes a period from when the disturbance current reaches the steady state until the output voltage of the fuel cell reaches the steady state.
Thereby, the following technical advantages are achieved: since the equivalent electrical model of a fuel cell always contains a resistive component and a capacitive component, in addition to transient voltage jumps, current pulses or interruptions can lead to a polarization-wise increase or decrease in the cell voltage, the voltage changes of these two phases being attributable to different electrochemical processes and therefore being able to reflect different loss mechanisms.
Optionally, information about the second or third loss mechanism is separated from the voltage slow-varying process by controlling the magnitude of the applied perturbation current and/or by stopping the supply of cathode reactant gas to the fuel cell.
Thereby, the following technical advantages are achieved: the dominant loss types differ at different current densities. In addition, cathode gas-cutoff discharge conditions can slow the reactant transport rate, thereby more clearly observing the decay in gas diffusion capability.
Optionally, the first loss mechanism comprises ohmic loss, the second loss mechanism comprises activation loss, and the third loss mechanism comprises mass transfer loss.
Optionally, the step S3 includes:
comparing the waveform of the output voltage response in the determined section with a reference voltage waveform; and
determining the following information according to the comparison result: and determining the influence degree of the loss mechanism corresponding to the section on the fuel cell.
Thereby, the following technical advantages are achieved: based on the comparison of the waveforms, the influences of different loss mechanisms on the fuel cell can be visualized, and the reliable observation of the health state of the fuel cell is realized.
Optionally, the step S3 includes:
determining a value of a determined parameter in an equivalent electrical model of the fuel cell based on a functional relationship that is satisfied and/or a voltage change amount of the output voltage response in the determined section;
comparing the value of the determined parameter with a reference value range; and
determining the following information according to the comparison result: the extent of the influence of the loss mechanism corresponding to the segment on the fuel cell is determined.
Thereby, the following technical advantages are achieved: based on the back-calculation of the electrical model parameters, the influence of the loss mechanism can be quantified, so that the state of health of the fuel cell can be described quantitatively by means of a mathematical model.
Optionally, the method further comprises the steps of:
comparing the degrees of influence of different loss mechanisms on the fuel cell with each other; and
and determining the leading reason causing the overall performance degradation of the fuel cell according to the comparison result.
Thereby, the following technical advantages are achieved: by knowing the leading cause of overall performance degradation, remedial or replacement measures can be taken more specifically, and in addition, valuable a priori data is provided for subsequent fuel cell performance improvement studies.
Alternatively, steps S2 and S3 are carried out for each segment of the fuel cell, in particular for each cell.
Thereby, the following technical advantages are achieved: this makes it possible to replace only those parts or cells of the fuel cell which are locally severely deteriorated, without the need to recall the entire fuel cell stack, so that assembly and maintenance costs can be saved in particular.
Optionally, the method further comprises the steps of: at least during the period when the disturbance current is present at the voltage converter, the battery as the sole electrical load is charged by means of the fuel cell.
Thereby, the following technical advantages are achieved: the storage battery can be used for absorbing the energy provided by the fuel cell during the health diagnosis, and the effective utilization of the electric energy is realized. In addition, the storage battery is used as the only electric load, so that adverse effects on the running state of conventional electric appliances in a vehicle caused by large-amplitude variation of the output voltage of the fuel cell can be avoided, and the safety is improved.
Optionally, the method further comprises the steps of: the output voltage response of the fuel cell is stored in a local or cloud server in association with the detection timing.
Thereby, the following technical advantages are achieved: by cumulatively storing the measurement results as the historical state data and sharing them, the previous measurement results can be recalled at each health diagnosis, thereby advantageously observing the time law of the change in the performance of the fuel cell.
According to a second aspect of the present invention, there is provided an apparatus for health diagnosis of a fuel cell in a vehicle environment, the apparatus being adapted to perform the method according to the first aspect of the present invention, the apparatus comprising:
a current perturbation unit configured to be able to apply a perturbation current on a voltage converter directly connected to the fuel cell, such that an electrical load state switching in the on-board electrical system is simulated by means of the perturbation current;
a measurement unit configured to be able to detect an output voltage response of the fuel cell; and
an analysis unit configured to be able to determine information related to different loss mechanisms from different segments of the output voltage response of the fuel cell.
Optionally, the apparatus further comprises a gas control unit configured to be able to stop the supply of the cathode reaction gas of the fuel cell.
According to a third aspect of the present invention, a computer program product is provided, wherein the computer program product comprises a computer program for implementing the method according to the first aspect of the present invention when executed by a computer.
Drawings
The principles, features and advantages of the present invention may be better understood by describing the invention in more detail below with reference to the accompanying drawings. The drawings include:
FIG. 1 shows a flow chart of a method for health diagnosis of a fuel cell in a vehicle environment according to an exemplary embodiment of the present invention;
FIG. 2 shows a block diagram of an apparatus for health diagnosis of a fuel cell in a vehicle environment, according to an exemplary embodiment of the present invention;
FIG. 3 shows a schematic diagram of an equivalent electrical model of a fuel cell;
FIG. 4 illustrates, in an exemplary embodiment, a diagram of an applied perturbation current and an output voltage response of a fuel cell;
FIG. 5 shows a schematic of an applied perturbation current and an output voltage response of a fuel cell in another exemplary embodiment; and
FIG. 6 shows a schematic of the applied perturbation current and the output voltage response of the fuel cell in another exemplary embodiment.
Detailed Description
In order to make the technical problems, technical solutions and advantageous technical effects of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and exemplary embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention.
Fig. 1 shows a flow chart of a method for health diagnosis of a fuel cell in a vehicle environment according to an exemplary embodiment of the invention.
In optional step S0, the supply of the reaction gas to the fuel cell is stopped. In this case, for example, the shut-off valve in the oxygen line on the cathode side of the fuel cell is closed. On the anode side, hydrogen continues to be supplied at the original flow rate and pressure, while the gas discharged from the anode side is recirculated to the fuel cell stack via the hydrogen recirculation line. Then, as the oxidation-reduction reaction proceeds, the remaining oxygen inside the fuel cell stack is gradually consumed, and thus the oxygen concentration becomes lower. The advantages of creating such conditions are: the cathode reactant transport rate can be indirectly controlled by controlling the cathode reactant concentration, which makes the loss mechanism associated with the reactant transport capability more clearly reflected by the output voltage response.
In step S1, a disturbance current is applied to a voltage converter which is directly connected to the fuel cell, so that an electrical load state switching in the on-board electrical system is simulated by means of the disturbance current. Depending on the power topology of the fuel cell vehicle, the application of the disturbing current can be effected on the DC/DC converter in case the fuel cell output is provided with a DC/DC converter, and on other nodes (for example on the DC/DC converter at the battery output or on the DC/AC converter between the fuel cell and the traction motor) in case no DC/DC converter dedicated to the fuel cell is present. Such load simulation can be realized by ensuring that the output current of the fuel cell can be directly controlled, regardless of whether a DC/DC converter is provided at the output terminal of the vehicle-mounted fuel cell.
Here, simulating an electrical load state switching in the on-board electrical system includes: at least some, in particular all, electrical loads in the on-board electrical system are simulated for being connected or removed. As an example, applying the perturbation current includes: a step current is applied to the voltage converter or the constant current originally applied to the voltage converter is interrupted and/or reduced to a determined value.
In step S2, the output voltage response of the fuel cell is detected. In this case, for example, the output voltage and the output current of the fuel cell can be measured directly by means of a voltage converter. Furthermore, the measurement can also be carried out by means of a further measuring unit in the vehicle. It is significant that it is no longer necessary to separately set a switch for controlling the access or removal of the variable load, nor to specially set the electrical consumers for consuming the energy generated during the test, nor to perform a disassembly operation of the fuel cell during the health diagnosis, and therefore a series of measurement operations can be performed with the fuel cell already installed in the vehicle.
In step S3, information relating to different loss mechanisms is determined from different segments of the output voltage response of the fuel cell. In this case, the different segments of the output voltage response can be divided into, for example, voltage abrupt (or linear) segments and voltage slowly varying (or polarization) segments. Here, each section corresponds to one or more loss mechanisms, and the loss mechanisms of each section are different from each other. These loss mechanisms include, for example: ohmic losses, activation losses and mass transfer losses.
Fig. 2 shows a block diagram of an apparatus for health diagnosis of a fuel cell in a vehicle environment according to an exemplary embodiment of the present invention.
The device 10 for state of health monitoring of a Fuel cell may be, for example, part of a Fuel Cell Control Unit (FCCU), but it may also be a separately provided device for health monitoring purposes. Also illustratively, as shown in fig. 2, at the output of the fuel cell 20, is externally connected a high voltage DC/DC converter 40, which is a component of the powertrain of a fuel cell electric vehicle that has direct access to the fuel cell stack and direct control of the fuel cell stack output current.
The apparatus 10 comprises a gas control unit 11, a current perturbation unit 12, a measurement unit 13 and an analysis unit 14. The gas control unit 11 is connected to intake and exhaust valves 50 on the cathode side of the fuel cell 20 to control the stop and start of supply of oxygen by controlling the on and off of these valves.
The current perturbation unit 12 is connected to the high voltage DC/DC converter 40. Generally, the DC/DC converter 40 is used to convert the output voltage of the fuel cell 20 and transmit the generated energy to the DC bus. In order to establish the conditions for the health diagnosis of the fuel cell 20 in the vehicle environment, a disturbance current may be applied to the DC/DC converter 40, for example, by means of the current disturbance unit 12. In this case, for example, a specified reference current i can be provided for the high-voltage DC/DC converter 40 by means of the current perturbation unit 12 ref By means of the reference current i ref The insertion or removal of an electrical load in the on-board electrical system can be simulated. Furthermore, the applied current density can also be freely adjusted by means of the current perturbation unit 12.
In response to a reference current i ref The fuel cell 20 adapts its output voltage and output current to this variation. For example, the fuel cell 20 is switched between the unloaded state and the fully loaded state depending on the reference current, and this output voltage response can be detected by the measurement unit 13. The measuring unit 13 can be part of a DC/DC converter 40, for example. It is also possible for the measuring unit 13 to be designed as a separate measuring device.
After detection of the output voltage response, these data are provided to the analysis unit 14, where the measured data can be subjected to signal processing and analysis operations in order to extract information about different loss mechanisms from different sections of the output voltage response. Here, the analysis unit 14 is connected to the cloud 30, whereby the analysis unit 14 can transmit information about various wear mechanisms as reference information to the cloud 30 or call history information from the cloud 30.
As an example, the analysis unit 14 recalls the reference voltage waveform of a determined segment of the output voltage response from the cloud 30 and compares it with the measured waveform in the determined segment. On the basis of the result of the comparison, the analysis unit 13 is able to determine the following information: the extent to which the wear mechanism corresponding to the segment affects the fuel cell 20 is determined. For example, by measuring the degree of deviation of the waveform from the reference waveform in the healthy state or from the standard humidity, it can be seen whether the degree of deterioration of the fuel cell 20 under a specific loss mechanism or the specific structural humidity satisfies the standard.
As another example, the analysis unit 14 calls a reference value range of a specific parameter in the equivalent electrical model of the fuel cell 20 from the cloud 30. Then, the analysis unit 14 finds the value of the determination parameter in the equivalent electrical model of the fuel cell 20 based on the voltage change amount of the voltage response and/or the satisfied functional relationship for the determination section of the output voltage response, and compares the value of the determination parameter with the reference value range. Based on the result of the comparison, the analysis unit determines the following information: the extent to which the wear mechanism corresponding to the segment affects the fuel cell 20 is determined.
As another example, the calibration database is pre-established in the cloud 30. For example, in advance, in the context of a degradation test, an output voltage response in the form of such a table of values or a family of characteristics is determined in a laboratory from one or more fuel cells of the same type, and the output voltage response is stored in a calibration database located in the cloud 30, with the corresponding degradation degree binding. Each time a health diagnosis of the fuel cell 20 is carried out in the vehicle by means of the device 10, a corresponding degree of deterioration can be recalled from the calibration database as soon as an output voltage response is detected.
Furthermore, the analysis unit 14 is also used to compare and rank the degrees of influence of the different loss mechanisms on the fuel cell 20 with each other, and then may determine the leading cause of the degradation in the overall performance of the fuel cell based on the comparison result.
Fig. 3 shows a schematic diagram of an equivalent electrical model of a fuel cell.
From an electrochemical point of view, the actual output voltage of a fuel cell can be represented by the ideal voltage minus a different type of voltage loss, which can be illustrated, for example, by the following equation:
U＝E thermo -η act -η ohmic -η conc
wherein U represents the actual output voltage of the fuel cell, E thermo Representing the thermodynamic predicted voltage, η, of the fuel cell act Represents the activation loss, eta, of the fuel cell ohmic Representing ohmic losses, η, of the fuel cell conc Representing the mass transfer loss of the fuel cell.
To enable analysis of the different loss mechanisms, an equivalent electrical model of the fuel cell as shown in fig. 3 was abstracted. In this case, the ohmic resistor R is used Ω The ohmic losses due to the internal resistances of the electrolyte and the electrodes of the fuel cell are characterized. By means of a Weber impedance Z of the Faraday impedances w And characterizing the loss of mass transfer of the reactant to the electrode due to the concentration difference, namely the mass transfer loss. By means of an electric double layer capacitor C dl And charge transfer resistance R in Faraday resistance f Collectively characterizing the activation loss of the fuel cell. Therefore, different loss mechanisms can be distinguished by reasonably utilizing the voltage change rules on different equivalent circuit elements.
FIG. 4 illustrates a schematic of the applied perturbation current and the output voltage response of the fuel cell in one exemplary embodiment.
The time course of the applied perturbation current is shown on the upper side of fig. 4, and the resulting output voltage response of the fuel cell is correspondingly shown on the lower side of fig. 4. At time t1, the current applied to the DC/DC converter is ramped down from I2 to I1, thereby simulating a certain amount of electrical load removal in the on-board electrical system external to the fuel cell. In response, the fuel cell switches, for example, from a full load state to an empty load state.
First, the output voltage of the fuel cell rapidly rises from the original full load voltage U0 to U1 at time t1, and this voltage jump 401 (or voltage immediate response) is caused by ohmic losses of the fuel cell, and thus follows ohm's law.
After time t1, the output voltage of the fuel cell slowly rises from U1 over time until it stabilizes at U2. It can be seen from the equivalent electrical model 300 of the fuel cell shown in FIG. 3, except that it is entirely composed of ohmic resistance R Ω The ohmic loss, the activation loss and the mass transfer loss caused by the two parts of the loss mechanism contain capacitance components, so that the voltage caused by the two parts of the loss mechanism cannot change suddenly, and a slow voltage change process 402 from t1 to t2 is presented.
In this case, the different loss mechanisms can be characterized not only by different circuit elements but also as a function of the current density. At low current densities, the activation kinetics dominate, but the mass transfer effect is negligible. At medium current densities, the activation loop is reduced and ohmic losses dominate. At high current densities, the activation loop will continue to decrease, but mass transfer effects begin to manifest. Therefore, by controlling the magnitude of the disturbance current applied to the DC/DC converter, different loss mechanisms can be more finely distinguished in the time period from t1 to t 2. In a vehicle environment, the magnitude of the current applied to the DC/DC converter is typically in the tens to hundreds of amperes, at which current density levels and under low current conditions created by current interruptions, it can be considered that mass transfer losses are not reflected here, so this slow voltage variation process 402 mainly reflects activation losses.
FIG. 5 shows a schematic of the applied perturbation current and the output voltage response of the fuel cell in another exemplary embodiment.
The time course of the applied perturbation current is shown on the upper side of fig. 5, and the resulting output voltage response of the fuel cell is correspondingly shown on the lower side of fig. 5. In this case, a reference current signal in the form of a step is applied to the DC/DC converter at time t1, so that the current at the DC/DC converter jumps from I1 to I2, thereby simulating a certain number of electrical loads being connected to the on-board electrical system connected externally to the fuel cell. In response, the output voltage of the fuel cell drops rapidly from the original voltage U2 to U1 at time t1, this voltage drop 501 being mainly caused by ohmic losses of the fuel cell. As the battery degradation progresses, the voltage drop of this portion will vary at different measurement times.
After time t1, the output voltage of the fuel cell slowly decreases from U1 over time until it stabilizes at U0. Also, the slow voltage transformation process 502 is caused by activation losses and mass transfer losses. By appropriately controlling the magnitude of the current applied to the DC/DC converter (e.g., to be at several tens of amperes), this voltage region 502 can be made to reflect only the activation loss.
FIG. 6 shows a schematic of the applied perturbation current and the output voltage response of the fuel cell in another exemplary embodiment.
The time course of the applied perturbation current is shown on the upper side of fig. 6, and the resulting output voltage response of the fuel cell is correspondingly shown on the lower side of fig. 6. The difference from fig. 5 is that, in order to further separate the influence of mass transfer loss from the process of slow voltage change, the reaction gas of the fuel cell cathode is shut off in advance before applying a perturbation current, so that a closed space is formed at the cathode side with respect to the outside air.
First, as an immediate response to the applied step current, the output voltage of the fuel cell drops rapidly from the original voltage U2 to U1 at time t1, this voltage drop 601 still being caused by ohmic losses of the fuel cell. During the time period from t1 to t2', the output voltage of the fuel cell slowly decreases from U1 to U0 over time, this voltage change process 602 being mainly caused by activation losses, but this part of the voltage change process 602 is not evident overall since the current in step form has reached a relatively large current density at time t 2. After time t2', as the cathode reactant gas is gradually consumed, the gas in the cathode flow channel is reduced, the reactant concentration between the flow channel and the catalyst layer is reduced, the transport rate is reduced, and therefore the concentration loss (i.e., mass transfer loss) is increased. Then, in the period from t2' to t2, the output voltage of the fuel cell will further slowly decrease from U0 until reaching 0, and this part of the voltage change process 603 is caused only by the mass transfer loss.
Especially on the cathode side, mass transfer losses associated with the transport of reactant gases and products to the catalyst layer are a major cause of reduced fuel cell performance. By this analysis process it is possible to achieve: in performing the health diagnosis, it is allowed to distinguish the ohmic loss of the fuel cell from the mass transfer loss, and the true ohmic internal resistance of the cell, which is not affected by the mass transfer effect of the cathode (including the catalyst layer) and the gas effective diffusivity, can be calculated.
Although specific embodiments of the invention have been described herein in detail, they have been presented for purposes of illustration only and are not to be construed as limiting the scope of the invention. Various substitutions, alterations, and modifications may be devised without departing from the spirit and scope of the present invention.
Claims (16)
1. A method for health diagnosis of a fuel cell (20) in a vehicle environment, the method comprising the steps of:
s1: applying a disturbance current to a voltage converter (40) directly connected to the fuel cell (20) in such a way that an electrical load state switching in the on-board electrical system is simulated by means of the disturbance current;
s2: detecting an output voltage response of the fuel cell (20); and
s3: information relating to different loss mechanisms is determined from different segments (401, 402) of the output voltage response of the fuel cell (20).
2. The method of claim 1, wherein the voltage converter (40) comprises a DC/DC converter and a DC/AC converter.
3. The method of claim 1 or 2, wherein simulating an electrical load state switching in an onboard electrical network comprises: the switching in or out of at least some, in particular all, electrical loads in the onboard electrical system is simulated.
4. The method of any of claims 1 to 3, wherein applying a perturbation current comprises:
increasing the originally applied constant current jump on the voltage converter (40) to a determined value, in particular applying a step current on the voltage converter; or
The constant current jump originally applied to the voltage converter (40) is reduced to a defined value, in particular interrupted.
5. The method according to any one of claims 1 to 4, wherein the method further comprises the steps of:
the supply of the cathode reaction gas to the fuel cell (20) is stopped before the application of the perturbation current.
6. The method according to any of claims 1 to 5, wherein the step S3 comprises:
determining information relating to a first loss mechanism from a voltage ramping process (401) over a first time period of an output voltage response; and
information relating to the second loss mechanism and/or the third loss mechanism is determined from a slow voltage change process (402) over a second period of the output voltage response, the second period following the first period.
7. The method of claim 6, wherein the first time period comprises a time period from when the perturbation current is applied until the perturbation current reaches a steady state, and the second time period comprises a time period from when the perturbation current reaches a steady state until the output voltage response of the fuel cell (20) reaches a steady state.
8. A method according to claim 6 or 7, wherein information about a second or third loss mechanism is separated from the slow voltage variation process (402) by controlling the magnitude of the applied perturbation current and/or by stopping the supply of cathode reactant gas of the fuel cell.
9. The method according to any one of claims 1 to 8, wherein said step S3 comprises:
comparing the waveform of the output voltage response in the determined section with a reference voltage waveform; and
determining the following information according to the comparison result: the extent to which the loss mechanism corresponding to the segment affects the fuel cell (20) is determined.
10. The method according to any one of claims 1 to 9, wherein the step S3 comprises:
determining a value of a determined parameter in an equivalent electrical model (300) of the fuel cell (20) based on a voltage change amount of the output voltage response in the determined section and/or a functional relationship satisfied in the determined section;
comparing the value of the determined parameter with a reference value range; and
determining the following information according to the comparison result: the extent to which the loss mechanism corresponding to the segment affects the fuel cell (20) is determined.
11. The method according to one of claims 1 to 10, wherein steps S2 and S3 are carried out for each section, in particular each cell, of the fuel cell (20).
12. The method according to any one of claims 1 to 11, wherein an on-board battery as the sole electrical load is charged by means of the fuel cell (20) at least during the presence of a disturbing current on the voltage converter (40).
13. The method according to any one of claims 1 to 12, wherein the method further comprises the steps of:
the output voltage response of the fuel cell (20) is stored in a local or cloud server (30) in association with the detection time.
14. An apparatus (10) for health diagnosing a fuel cell (20) in a vehicle environment, the apparatus (10) being adapted to perform the method according to any one of claims 1 to 13, the apparatus (10) comprising:
a current perturbation unit (12) configured to be able to apply a perturbation current on a voltage converter (40) directly connected to the fuel cell (20) such that an electrical load state switching in the on-board electrical system is simulated by means of the perturbation current;
a measurement unit (13) configured to be able to detect an output voltage response of the fuel cell (20); and
an analysis unit (14) configured to be able to determine information related to different loss mechanisms from different sections of the output voltage response of the fuel cell (20).
15. The apparatus (10) according to claim 14, the apparatus (10) further comprising a gas control unit (11) configured to be able to stop the supply of cathode reactant gas to the fuel cell (20).
16. A computer program product, wherein the computer program product comprises a computer program for implementing the method according to any one of claims 1 to 13 when executed by a computer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111157277.1A CN115882012A (en) | 2021-09-30 | 2021-09-30 | Method and apparatus for health diagnosis of fuel cell in vehicle environment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202111157277.1A CN115882012A (en) | 2021-09-30 | 2021-09-30 | Method and apparatus for health diagnosis of fuel cell in vehicle environment |
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