Performance protection method and system for CVM-free fuel cell

Abstract

The invention discloses a performance protection method and system for a CVM-free fuel cell, and the method comprises the steps: collecting an electric pile voltage value, a cooling liquid pile entering temperature value and an air flow value of the fuel cell, so as to obtain an electric pile voltage deviation parameter, a cooling liquid pile entering temperature deviation parameter and an air flow deviation parameter of the fuel cell; carrying out performance judgment on the fuel cell according to the electric pile voltage deviation parameter, the cooling liquid in-pile temperature deviation parameter and the air flow deviation parameter; and when the performance state is in a decline state, executing a preset performance protection operation on the fuel cell so as to prolong the service life of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell technology, and in particular to a performance protection method and system for a CVM-free fuel cell. Background Art

[0002] With the development of science and technology and the emphasis on environmental protection, clean and pollution-free energy has gradually been applied to various power systems. Among them, fuel cells that directly convert the chemical energy of hydrogen into electrical energy through electrochemical reactions have naturally been used in more and more fields.

[0003] A fuel cell is a device that uses a stack as its core and other subsystems to work together. In actual fuel cell applications, the battery performance often deteriorates due to water flooding inside the battery due to insufficient drainage. If the water flooding is not promptly addressed and the fuel cell is continued to be used, the battery performance will also decline rapidly, thus affecting the battery life.

[0004] In the prior art, a CVM inspection device, i.e., a single-chip voltage inspection device, is usually installed inside the fuel cell to monitor the battery performance. However, when there is no CVM inspection device inside the fuel cell or the CVM inspection device fails, the battery performance cannot be monitored. At the same time, the prior art can only monitor the battery performance degradation, but cannot determine the cause of the fuel cell performance degradation, and thus cannot timely and accurately protect the fuel cell performance according to the degradation cause, resulting in a shortened fuel cell service life. Summary of the invention

[0005] In order to solve the above technical problems, the present invention discloses a performance protection method and system for a CVM-free fuel cell, which are used to timely protect the performance of the fuel cell to extend the service life of the fuel cell.

[0006] In order to achieve the above object, the present invention discloses a performance protection method for a CVM-free fuel cell, comprising:

[0007] Collecting the stack voltage value, coolant inlet temperature value and air flow value of the fuel cell to obtain the stack voltage deviation parameter, coolant inlet temperature deviation parameter and air flow deviation parameter of the fuel cell;

[0008] Performing performance determination on the fuel cell according to the stack voltage deviation parameter, the coolant inlet temperature deviation parameter and the air flow deviation parameter to obtain the performance status of the fuel cell;

[0009] When the performance state is in a declining state, a preset performance protection operation is performed on the fuel cell.

[0010] The present invention discloses a performance protection method for a CVM-free fuel cell, which monitors the performance of the fuel cell by collecting the real-time operating data of the fuel cell, namely, the stack voltage value, the coolant inlet temperature value and the air flow value of the fuel cell, so as to timely and accurately monitor whether the performance of the fuel cell has declined. Specifically, when performing performance evaluation, the performance evaluation result is obtained in a timely manner by obtaining the stack voltage deviation parameter of the fuel cell, and the coolant inlet temperature deviation parameter and the air flow deviation parameter can be used to reflect the influence of external factors on the performance of the fuel cell, thereby improving the accuracy of the performance status evaluation. Finally, using the evaluation result of the performance status, a preset performance protection operation is performed on the fuel cell to increase the service life of the fuel cell.

[0011] As a preferred example, the collecting of the fuel cell stack voltage value, the coolant inlet temperature value and the air flow value includes:

[0012] According to a preset detection cycle, obtaining a first voltage value of the fuel cell stack corresponding to the beginning of each detection cycle and a second voltage value corresponding to the end of the detection cycle;

[0013] Obtaining a first temperature value corresponding to the coolant inlet of the stack at the beginning of each detection cycle and a second temperature value corresponding to the end of each detection cycle;

[0014] A first air flow value of an air inlet of the fuel cell stack in a detection cycle before a current detection cycle and a second air flow value in a current detection cycle are obtained.

[0015] The present invention uses a detection cycle to acquire data and timely monitor the performance degradation of the fuel cell. Among them, by acquiring the voltage of the fuel cell stack during the detection cycle, the voltage can be used to intuitively reflect the characteristics of the performance change of the fuel cell, thereby improving the accuracy and timeliness of performance degradation monitoring. At the same time, the coolant temperature and air flow of the stack during the detection cycle are acquired to determine whether the performance degradation of the fuel cell is affected by external factors or the performance degradation of the stack itself, so as to accurately perform performance protection operations on the fuel cell.

[0016] As a preferred example, the step of obtaining a fuel cell stack voltage deviation parameter, a coolant inlet temperature deviation parameter, and an air flow deviation parameter includes:

[0017] Obtaining the current density of the fuel cell in each detection cycle to obtain the standard voltage value, standard temperature value and standard air flow value of the fuel cell stack under the current density;

[0018] Acquire a first voltage deviation value between the first voltage value and the standard voltage value and a second voltage deviation value between the second voltage value and the standard voltage value, so as to use the difference between the first voltage deviation value and the second voltage deviation value as a voltage deviation rate value of the fuel cell in a current detection cycle;

[0019] Acquire a first temperature deviation value between the first temperature value and the standard temperature value and a second temperature deviation value between the second temperature value and the standard temperature value, so as to use the difference between the first temperature deviation value and the second temperature deviation value as a temperature deviation rate value of the fuel cell in a current detection cycle;

[0020] A first air flow deviation value between the first air flow value and the standard air flow value and a second air flow deviation value between the second air flow value and the standard air flow value are obtained, so as to use the difference between the first air flow deviation value and the second air flow deviation value as the air flow deviation rate value of the fuel cell in the current detection cycle.

[0021] The present invention uses the deviation value between the real-time voltage and the standard voltage and the change value of the deviation value in a detection cycle to reflect the voltage fluctuation of the battery and the deviation between the voltage and the standard voltage, so as to improve the accuracy of battery performance degradation through the voltage fluctuation and the deviation between the voltage and the standard voltage. Similarly, in a detection cycle, the deviation value between the real-time temperature, the real-time air flow rate and the standard temperature and the standard air flow rate and the change value of the deviation value in a detection cycle are used to reflect the fluctuation of external factors, so as to improve the accuracy of performance degradation cause analysis through the fluctuation of the external factors.

[0022] As a preferred example, the step of determining the performance of the fuel cell and obtaining the performance status of the fuel cell includes:

[0023] evaluating the performance state of the fuel cell according to a preset voltage deviation threshold and a preset first voltage deviation rate threshold;

[0024] When the first voltage deviation value is greater than the voltage deviation threshold, the second voltage deviation value is greater than the voltage deviation threshold, and the voltage deviation rate value is greater than the first voltage deviation rate threshold, it is determined that the performance state of the fuel cell is in a declining state.

[0025] The present invention first sets the threshold value to determine whether the voltage fluctuation of the fuel cell stack is too large and whether the voltage of the fuel cell stack deviates too much from the standard voltage according to the threshold value, and then improves the accuracy of performance degradation monitoring by combining the fluctuation and the deviation, so as to timely protect the performance of the fuel cell.

[0026] As a preferred example, the step of determining the performance of the fuel cell and obtaining the performance status of the fuel cell includes:

[0027] When it is determined that the performance state of the fuel cell is in a declining state, the reason for the performance decline of the fuel cell is obtained based on the first temperature deviation value, the second temperature deviation value, the temperature deviation rate value, the first air flow deviation value, the second air flow deviation value and the air flow deviation rate value of the fuel cell stack.

[0028] After determining that the fuel cell is currently in a state of performance degradation, the present invention needs to determine whether the battery performance degradation is caused by external factors or the battery performance degradation caused by the fuel cell stack itself, so as to determine whether to perform protection operations based on the cause determination result to avoid useless execution of protection operations.

[0029] As a preferred example, the obtaining of the reason for the performance degradation of the fuel cell includes:

[0030] When the first temperature deviation value is greater than or equal to a preset temperature deviation threshold, the second temperature deviation value is greater than or equal to the temperature deviation threshold, and the temperature deviation rate value is greater than or equal to a preset temperature deviation rate threshold, determining that the coolant temperature is the cause of the performance degradation of the fuel cell;

[0031] When the first temperature deviation value is less than the temperature deviation threshold, the second temperature deviation value is less than the temperature deviation threshold, the temperature deviation rate value is less than the preset temperature deviation rate threshold, and the first air flow deviation value is greater than or equal to the preset air flow deviation threshold, the second air flow deviation value is greater than or equal to the air flow deviation threshold, and the air flow deviation rate value is greater than or equal to the preset air flow deviation rate threshold, it is determined that the air flow is the cause of the performance degradation of the fuel cell.

[0032] When analyzing the causes of battery performance degradation, the present invention first evaluates the temperature of the coolant to determine whether the temperature change and fluctuation of the coolant are abnormal. After eliminating the influence of the coolant temperature on the battery performance, the deviation and fluctuation of the air flow are analyzed to determine whether the performance of the fuel cell stack is degraded due to the interference of the coolant temperature or the air flow.

[0033] As a preferred example, the performing of a preset performance protection operation on the fuel cell includes:

[0034] When the first air flow deviation value is less than a preset air flow deviation threshold, the second air flow deviation value is less than the air flow deviation threshold, and the air flow deviation rate value is less than the preset air flow deviation rate threshold, it is determined that the performance degradation of the fuel cell stack is caused by the performance degradation of the fuel cell and a preset performance protection operation is performed on the fuel cell.

[0035] The present invention eliminates the interference of external factors on the performance of the fuel cell, accurately identifies the decline in the performance of the fuel cell stack itself, and then uses a preset performance protection operation to protect the performance of the fuel cell stack to improve the accuracy of the performance protection.

[0036] As a preferred example, the performing of a preset performance protection operation on the fuel cell includes:

[0037] Increase the air flow and throttle opening of the stack cathode, and keep the target pressure at the stack air inlet unchanged;

[0038] Increasing the speed of the hydrogen pump of the anode of the stack and shortening the opening period of the hydrogen tail exhaust valve of the anode of the stack;

[0039] The temperature of the coolant inlet of the stack is increased.

[0040] The present invention performs corresponding performance protection operations from three aspects: the cathode of the fuel cell stack, the anode of the fuel cell stack, and the coolant of the fuel cell stack, so as to improve the effect of performance protection through comprehensive performance protection operations, thereby extending the service life of the fuel cell.

[0041] As a preferred example, the performing of a preset performance protection operation on the fuel cell includes:

[0042] When the first voltage deviation value is less than or equal to a preset voltage deviation threshold, the second voltage deviation value is less than or equal to the voltage deviation threshold, and the voltage deviation rate value is greater than a preset second voltage deviation rate threshold, the performance protection operation is stopped.

[0043] While performing performance protection operations on the fuel cell, the present invention obtains the voltage deviation value and the voltage deviation rate value of the stack in real time, so as to stop performing the performance protection operation when it is determined that the performance protection of the stack is within a preset range, thereby avoiding damage to the battery caused by excessive performance protection and ensuring the effect of performance protection.

[0044] On the other hand, the present invention also discloses a performance protection system for a CVM-free fuel cell, including a data acquisition module, a performance evaluation module and a performance protection module;

[0045] The data acquisition module is used to collect the stack voltage value, coolant inlet temperature value and air flow value of the fuel cell to obtain the stack voltage deviation parameter, coolant inlet temperature deviation parameter and air flow deviation parameter of the fuel cell;

[0046] The performance evaluation module is used to determine the performance of the fuel cell according to the stack voltage deviation parameter, the coolant inlet temperature deviation parameter and the air flow deviation parameter, and obtain the performance status of the fuel cell;

[0047] The performance protection module is used to perform a preset performance protection operation on the fuel cell when the performance state is in a declining state.

[0048] The present invention discloses a performance protection system for a CVM-free fuel cell, which monitors the performance of the fuel cell by collecting the real-time operating data of the fuel cell, namely, the stack voltage value, the coolant inlet temperature value and the air flow value of the fuel cell, so as to timely and accurately monitor whether the performance of the fuel cell has declined. Specifically, when performing performance evaluation, the performance evaluation result is obtained in a timely manner by obtaining the stack voltage deviation parameter of the fuel cell, and the coolant inlet temperature deviation parameter and the air flow deviation parameter can be used to reflect the influence of external factors on the performance of the fuel cell, thereby improving the accuracy of the performance status evaluation. Finally, using the evaluation result of the performance status, the preset performance protection operation is performed on the fuel cell to increase the service life of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 : A flow chart of a performance protection method for a CVM-free fuel cell provided in an embodiment of the present invention;

[0050] Figure 2 : A schematic structural diagram of a performance protection system for a CVM-free fuel cell provided in an embodiment of the present invention;

[0051] Figure 3 : A schematic flow chart of a performance protection method for a CVM-free fuel cell provided in another embodiment of the present invention;

[0052] Figure 4 : A flow chart of a performance determination logic provided by another embodiment of the present invention;

[0053] Figure 5 : A flow chart of a performance protection operation provided for another embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] Embodiment 1

[0056] This embodiment discloses a performance protection method for a CVM-free fuel cell. For the specific implementation process of the protection method, please refer to Figure 1 , mainly including step 101 to step 103, the above steps are mainly:

[0057] Step 101: Collect the stack voltage value, coolant inlet temperature value and air flow value of the fuel cell to obtain the stack voltage deviation parameter, coolant inlet temperature deviation parameter and air flow deviation parameter of the fuel cell.

[0058] Step 102: Determine the performance of the fuel cell according to the stack voltage deviation parameter, the coolant inlet temperature deviation parameter and the air flow deviation parameter to obtain the performance status of the fuel cell.

[0059] Step 103: When the performance state of the fuel cell is in a declining state, a preset performance protection operation is performed on the fuel cell.

[0060] In certain implementations of this embodiment, when various deviation parameters of the fuel cell are obtained through step 101 to monitor the performance of the fuel cell, in order to improve the timeliness and accuracy of performance monitoring, this embodiment can collect data by setting a detection cycle and obtain different data values ​​corresponding to the same type of data before and after the same cycle, so as to accurately perform performance evaluation.

[0061] Specifically, referring to the above data collection method and the requirements for the data type collected, in some implementations of this embodiment, step 101 can complete the acquisition of the stack voltage deviation parameter, the coolant inlet temperature deviation parameter and the air flow deviation parameter through the following steps:

[0062] Step 1011: According to a preset detection cycle, obtain a first voltage value of the fuel cell stack corresponding to the beginning of each detection cycle and a second voltage value corresponding to the end of the detection cycle; obtain a first temperature value of the coolant inlet of the stack corresponding to the beginning of each detection cycle and a second temperature value corresponding to the end of the detection cycle; obtain a first air flow value of the air inlet of the stack in a detection cycle before the current detection cycle and a second air flow value in the current detection cycle.

[0063] Step 1012: Obtain the current density of the fuel cell in each detection cycle to obtain the standard voltage value, standard temperature value and standard air flow value of the fuel cell stack under the same current density; obtain a first voltage deviation value between the first voltage value and the standard voltage value and a second voltage deviation value between the second voltage value and the standard voltage value, so as to use the difference between the first voltage deviation value and the second voltage deviation value as the voltage deviation rate value of the fuel cell in the current detection cycle; obtain a first temperature deviation value between the first temperature value and the standard temperature value and a second temperature deviation value between the second temperature value and the standard temperature value, so as to use the difference between the first temperature deviation value and the second temperature deviation value as the temperature deviation rate value of the fuel cell in the current detection cycle; obtain a first air flow deviation value between the first air flow value and the standard air flow value and a second air flow deviation value between the second air flow value and the standard air flow value, so as to use the difference between the first air flow deviation value and the second air flow deviation value as the air flow deviation rate value of the fuel cell in the current detection cycle.

[0064] In some implementations of this embodiment, after obtaining the voltage value, temperature value and air flow value of the stack in the same detection cycle with reference to step 1011, the actual voltage of the fuel cell stack before and after the detection cycle can be used to reflect the voltage fluctuation, thereby realizing the monitoring of the battery performance degradation. At the same time, the coolant temperature and air flow of the stack in the same detection cycle are obtained to determine whether the performance degradation of the fuel cell is affected by external factors or the performance degradation of the stack itself, so as to accurately perform performance protection operations on the fuel cell.

[0065] Furthermore, in some embodiments, based on the voltage value, temperature value and air flow value extracted in step 1011, the deviation value between the real-time voltage and the standard voltage and the change value of the deviation value in a detection cycle obtained in step 1012 reflect the voltage fluctuation of the battery and the deviation between the voltage and the standard voltage, so as to improve the accuracy of battery performance degradation through the voltage fluctuation and the deviation between the real-time voltage and the standard voltage. Similarly, in a detection cycle, the deviation value between the real-time temperature, the real-time air flow and the standard temperature and the standard air flow and the change value of the deviation value in a detection cycle reflect the fluctuation of external factors, so as to improve the accuracy of performance degradation cause analysis through the fluctuation of external factors.

[0066] In certain implementations of this embodiment, after obtaining data for evaluating the performance of the fuel cell in step 101, step 102 needs to determine the performance degradation and the cause of the battery performance degradation based on the above-obtained data. Specifically, step 102 obtains a specific determination result through the following steps:

[0067] Step 1021: Evaluate the performance status of the fuel cell based on a preset voltage deviation threshold and a preset first voltage deviation rate threshold; when the first voltage deviation value is greater than the voltage deviation threshold, the second voltage deviation value is greater than the voltage deviation threshold, and the voltage deviation rate value is greater than the first voltage deviation rate threshold, determine that the performance status of the fuel cell is in a declining state.

[0068] Step 1022: When it is determined that the performance state of the fuel cell is in a declining state, the reason for the performance decline of the fuel cell is obtained based on the first temperature deviation value, the second temperature deviation value, the temperature deviation rate value, the first air flow deviation value, the second air flow deviation value and the air flow deviation rate value of the fuel cell stack.

[0069] In some implementations of this embodiment, step 1021 first sets a threshold value to determine whether the voltage fluctuation of the battery stack is too large and whether the voltage of the battery stack deviates too much from the standard voltage according to the threshold value, thereby improving the accuracy of performance degradation monitoring by combining fluctuations and deviations, and timely protecting the performance of the fuel cell. After the performance degradation determination result is output in step 1021, step 1022 needs to determine whether the battery performance degradation is caused by external factors or the battery performance degradation caused by the battery stack itself, so as to determine whether to perform the protection operation according to the cause determination result to avoid useless execution of the protection operation.

[0070] Specifically, in the process of analyzing the reasons for the battery performance degradation in step 1022, based on the coolant temperature data and air flow data collected in step 101, it is necessary to analyze whether the coolant temperature or air flow is the reason for the battery performance degradation in the specific analysis process. The process of analyzing the reasons for the performance degradation in step 1022 specifically includes the following steps:

[0071] Step 10221: when the first temperature deviation value is greater than or equal to a preset temperature deviation threshold, the second temperature deviation value is greater than or equal to the temperature deviation threshold, and the temperature deviation rate value is greater than or equal to the preset temperature deviation rate threshold, it is determined that the coolant temperature is the cause of the performance degradation of the fuel cell;

[0072] Step 10222: when the first temperature deviation value is less than the temperature deviation threshold, the second temperature deviation value is less than the temperature deviation threshold, the temperature deviation rate value is less than the preset temperature deviation rate threshold, and the first air flow deviation value is greater than or equal to the preset air flow deviation threshold, the second air flow deviation value is greater than or equal to the air flow deviation threshold, and the air flow deviation rate value is greater than or equal to the preset air flow deviation rate threshold, it is determined that the air flow is the cause of the performance degradation of the fuel cell;

[0073] Step 10223: When the first air flow deviation value is less than the preset air flow deviation threshold, the second air flow deviation value is less than the air flow deviation threshold, and the air flow deviation rate value is less than the preset air flow deviation rate threshold, it is determined that the degradation of the stack performance is caused by the degradation of the fuel cell performance.

[0074] In certain implementations of this embodiment, when analyzing the causes of the decline in battery performance, step 10221 first evaluates the temperature of the coolant to determine whether the temperature change and fluctuation of the coolant are abnormal. After eliminating the influence of the coolant temperature on the battery performance through step 10221, step 10222 analyzes the deviation and fluctuation of the air flow to determine whether the performance of the fuel cell stack is reduced due to the interference of the coolant temperature or the air flow. Finally, when the interference of external factors on the performance of the fuel cell is eliminated through steps 10221 and 10222, step 10223 accurately identifies that the performance of the stack itself has declined, and the execution of the performance protection operation can be triggered at this time to accurately achieve the performance protection of the battery.

[0075] In some implementations of this embodiment, when it is determined in step 102 that the performance degradation of the fuel cell stack inside the fuel cell leads to the degradation of the fuel cell performance, in order to protect the performance of the fuel cell stack, an operation for protecting the performance needs to be performed on the fuel cell stack. Specifically, the performance protection operation set in step 103 includes:

[0076] Step 1031: Increase the air flow rate and throttle opening of the cathode of the fuel cell stack, and maintain the target pressure at the air inlet of the fuel cell stack unchanged.

[0077] Step 1032: Increase the speed of the hydrogen pump of the stack anode and shorten the opening period of the hydrogen tail exhaust valve of the stack anode.

[0078] Step 1033: Increase the temperature of the coolant inlet of the fuel cell stack.

[0079] In certain implementations of this embodiment, step 103 performs corresponding performance protection operations from three aspects: the cathode of the fuel cell stack, the anode of the fuel cell stack, and the coolant of the fuel cell stack, so as to improve the effect of performance protection through comprehensive performance protection operations, thereby extending the service life of the fuel cell.

[0080] Furthermore, when step 103 protects the performance of the fuel cell stack through the operations shown in step 1031 to step 1033, in order to avoid the above-mentioned performance protection operation from lasting too long and damaging the fuel cell, it is necessary to constantly obtain the performance status of the current fuel cell after the performance protection operation is performed to determine whether to stop the execution of the above-mentioned performance protection operation. Specifically, the determination condition for stopping the execution of the performance protection operation in step 103 is:

[0081] Step 1034: When the first voltage deviation value is less than or equal to the preset voltage deviation threshold, the second voltage deviation value is less than or equal to the voltage deviation threshold, and the voltage deviation rate value is greater than the preset second voltage deviation rate threshold, stop executing the performance protection operation.

[0082] In certain implementations of this embodiment, step 1034 is used to obtain the voltage deviation value and voltage deviation rate value of the battery stack in real time, so that when it is determined that the performance protection of the battery stack is within a preset range, the performance protection operation is stopped, thereby avoiding damage to the battery due to excessive performance protection and ensuring the effectiveness of performance protection.

[0083] On the other hand, this embodiment also discloses a performance protection system for a CVM-free fuel cell. Specifically, the specific structural composition of the performance protection system is shown in FIG. Figure 2 , mainly includes a data acquisition module 201, a performance evaluation module 202 and a performance protection module 203.

[0084] The data acquisition module 201 is used to collect the stack voltage value, coolant inlet temperature value and air flow value of the fuel cell to obtain the stack voltage deviation parameter, coolant inlet temperature deviation parameter and air flow deviation parameter of the fuel cell;

[0085] The performance evaluation module 202 is used to determine the performance of the fuel cell according to the stack voltage deviation parameter, the coolant inlet temperature deviation parameter and the air flow deviation parameter, and obtain the performance status of the fuel cell;

[0086] The performance protection module 203 is used to perform a preset performance protection operation on the fuel cell when the performance state of the fuel cell is in a declining state.

[0087] The present embodiment discloses a performance protection method and system for a CVM-free fuel cell, which monitors the performance of the fuel cell by collecting the real-time operating data of the fuel cell, namely, the stack voltage value, the coolant inlet temperature value and the air flow value of the fuel cell, so as to timely and accurately monitor whether the performance of the fuel cell has declined. Specifically, when performing performance evaluation, the performance evaluation results are obtained in a timely manner by obtaining the stack voltage deviation parameters of the fuel cell, and the coolant inlet temperature deviation parameters and the air flow deviation parameters can be used to reflect the influence of external factors on the performance of the fuel cell, thereby improving the accuracy of the performance status evaluation. Finally, using the evaluation results of the performance status, the preset performance protection operation is performed on the fuel cell to increase the service life of the fuel cell.

[0088] Embodiment 2

[0089] With the development of hydrogen energy, hydrogen fuel cells that directly convert the chemical energy of hydrogen into electrical energy through electrochemical reactions have been increasingly used. Therefore, timely detection of fuel cell performance degradation and performance protection of fuel cells have become an important direction for fuel cell performance research. The prior art performs performance testing by setting a CVM inspection device inside the fuel cell. However, due to the manufacturing cost of the battery, not all fuel cells have a CVM inspection device. When the battery performance of a fuel cell without CVM is reduced, it is impossible to determine whether the fuel cell has a single low and reverse polarity reaction battery performance degradation phenomenon. At this time, if the current of the battery is continued to be pulled, the performance of the battery will be greatly reduced, affecting the battery life. At the same time, even if a CVM inspection device is installed inside the battery, because the CVM inspection device can only perform battery performance testing, it is impossible to determine the cause of the battery performance degradation, and thus it is impossible to perform performance protection operations on the battery in a targeted manner, resulting in poor battery performance protection effect.

[0090] In order to solve the above technical problems, this embodiment discloses a performance protection method for a CVM-free fuel cell, which detects the voltage of the internal stack of the fuel cell for performance detection, and analyzes the cause of the performance degradation of the fuel cell by detecting the temperature of the coolant inside the fuel cell and the air flow at the air inlet of the battery, thereby performing corresponding performance protection operations to extend the service life of the fuel cell. Specifically, the specific implementation process of the performance protection method provided in this embodiment can be referred to Figure 3 , mainly including steps 301 to 305.

[0091] Step 301: Collect the stack voltage parameters, coolant temperature parameters and air flow parameters of the fuel cell in the current detection cycle to calculate the voltage deviation parameters, coolant temperature deviation parameters and air flow deviation parameters.

[0092] Specifically, in this embodiment, in order to obtain the real-time performance test results of the fuel cell in a timely manner, the parameters of the fuel cell can be obtained in real time for performance evaluation. However, since the parameters of the fuel cell are volatile, in order to improve the accuracy of the performance evaluation, the detection period can be set to reduce the impact of data fluctuations on the accuracy of performance detection according to the detection period. Furthermore, the duration range based on the detection period will affect the effect of data collection. When the value of the period is too large or too small, it will affect the accuracy of performance evaluation. To this end, this embodiment can obtain the accuracy of performance evaluation under different detection periods through experiments to formulate the duration of the detection period. For example, in some embodiments of this embodiment, it is experimentally found that when the value of the detection period is 100ms, that is, the period t=100ms, the accuracy of performance evaluation is the highest, and the value of the detection period is set to 100ms.

[0093] Furthermore, after the detection cycle is set, the voltage of the internal stack of the fuel cell, the coolant temperature and the air flow are simultaneously obtained within the same detection cycle to evaluate the performance degradation and the causes of the performance degradation.

[0094] Specifically, the performance of a fuel cell or fuel cell system is most directly reflected in the comparison between the reference voltage and the actual voltage of the stack at the same electrical density point, and this comparison is mainly divided into voltage deviation and voltage deviation rate. Among them, the voltage deviation refers to the difference between the reference voltage corresponding to the electrical density point of the current detection cycle and the actual voltage collected in the current detection cycle. The greater the difference between the reference voltage and the actual voltage, the farther the voltage deviation is from the reference voltage. The voltage deviation rate refers to the change of the difference in the current detection cycle, that is, the deviation change rate. The greater the deviation rate, the greater the voltage fluctuation.

[0095] Specifically, the voltage deviation is set to E_U, and the real-time voltage corresponding to the fuel cell under the current density in the current detection cycle is VT_HV3. The real-time voltage VT_HV3 includes the voltage corresponding to the beginning of the detection cycle and the voltage corresponding to the end of the detection cycle. At the same time, the reference voltage under the current density is set to U_Ref, and the current voltage deviation calculation formula is as follows:

[0096] E_U=U_Ref-VT_HV3

[0097] Assuming that the voltage deviation rate is EC_U, the deviation value between the real-time voltage collected before the start of the cycle and the standard voltage is E_U1, and the deviation value between the real-time voltage collected at the end of the cycle and the standard voltage is E_U2. The calculation formula for the voltage deviation rate of the fuel cell in the current cycle is as follows:

[0098] EC_U=E_U2-E_U1

[0099] In summary, this embodiment obtains the first voltage value of the fuel cell stack corresponding to the beginning of each detection cycle and the second voltage value corresponding to the end of the detection cycle, which are used to calculate the voltage deviation parameter of the fuel cell in the current detection cycle.

[0100] In certain implementations of this embodiment, on the basis of obtaining the voltage deviation parameter to intuitively reflect the performance of the fuel cell, the performance of the fuel cell or fuel cell system is related to other factors in addition to the performance of its own stack, mainly the coolant stack inlet temperature and the amount of reactants. Among them, the reactants are oxygen and hydrogen in the air. Insufficient reactants will also cause the performance of the fuel cell to decline, and whether the amount of reactants is sufficient is mainly related to the air flow. In this regard, the coolant temperature value and the air flow value within the same detection cycle are obtained to obtain the reasons for the decline in fuel cell performance for analysis.

[0101] Specifically, a temperature sensor is set at the coolant inlet of the fuel cell stack, and the temperature at the coolant stack inlet is collected by the temperature sensor as the coolant temperature value. Assuming that the coolant stack inlet temperature deviation is E_TT, the coolant stack inlet temperature at the current moment is TT, and the coolant stack target inlet temperature at the current moment is TT_Ref. Among them, the coolant stack inlet temperature at the current moment includes the temperature corresponding to the beginning of the detection cycle and the temperature corresponding to the end of the detection cycle, and the current temperature deviation calculation formula is as follows:

[0102] E_TT=TT_Ref-TT

[0103] Assuming that the temperature deviation rate is EC_TT, the deviation value between the real-time temperature collected before the start of the cycle and the target inlet temperature is E_TT1, and the deviation value between the real-time temperature collected at the end of the cycle and the target temperature is E_TT2. The current temperature deviation rate calculation formula is as follows:

[0104] EC_TT=E_TT2-E_TT1

[0105] Similarly, an air flow meter is provided at the air inlet of the fuel cell system, and the air flow entering the fuel cell system is fed back through the air flow meter. Since the air flow in the same detection cycle is the same, in order to reflect the impact of the fluctuation of the air flow on the performance of the fuel cell. In a certain implementation of this embodiment, the air flow values ​​in two adjacent cycles are collected to calculate the corresponding air flow deviation and air flow deviation rate. Specifically, the air flow deviation E_F, the current air flow F, and the current air flow F_Ref are set, and the current air flow deviation calculation formula is as follows:

[0106] E_F=F_Ref-F

[0107] The air flow deviation rate EC_F is designed to be calculated, the air flow deviation of the previous cycle is E_F1, and the air flow deviation of the current cycle is E_F2. The current air flow deviation rate calculation formula is as follows:

[0108] EC_F=E_F2-E_F1

[0109] This embodiment uses air flow deviation and air flow deviation rate to eliminate interference caused by performance degradation of the fuel cell stack due to the influence of reactants.

[0110] Step 302: According to the voltage deviation parameter, the coolant temperature deviation parameter and the air flow deviation parameter, a preset performance determination logic is used to determine whether the fuel cell stack's own performance has decreased.

[0111] Specifically, in this embodiment, after obtaining the voltage deviation value E_U and the voltage deviation rate EC_U, a preset performance determination logic is used to determine whether the performance of the fuel cell stack itself has deteriorated.

[0112] In some real-time modes of this embodiment, such as Figure 4 shown, a performance determination logic is provided to obtain the determination result of the deterioration of the performance of the fuel cell stack itself. Specifically, as Figure 4 shown, first, a preset voltage determination sequence is executed to obtain the quality of the fuel cell stack performance according to the voltage determination sequence. Among them, the voltage deviation threshold is set as U1, and the voltage deviation rate threshold is set as U2. When E_U > U1, it means that the current fuel cell stack voltage deviation from the target voltage is large and the performance is poor; when EC_U > U2, it means that the current voltage fluctuation is large. When both E_U > U1 and EC_U > U2 are satisfied, it is determined that the performance of the fuel cell stack is relatively poor at this time.

[0113] After determining that the performance of the fuel cell stack is relatively poor, it is necessary to analyze the reasons for the deterioration of the fuel cell stack performance. At this time, first, a preset coolant temperature determination sequence is used to determine whether the poor performance of the fuel cell stack is caused by the coolant temperature. Specifically, the coolant temperature determination sequence is: the coolant temperature deviation threshold is set as T1, and the coolant temperature deviation rate threshold is set as T2. When E_TT < T1, it means that the current coolant temperature deviation of the fuel cell stack from the target temperature is small; when EC_TT < T2, it means that the current coolant temperature fluctuation of the fuel cell stack is small. When both E_TT < T1 and EC_TT < T2 are satisfied, it indicates that the poor performance of the fuel cell stack at this time is not caused by the coolant temperature, excluding the interference of the coolant temperature factor. Only then is it switched to the preset air flow determination sequence to determine whether the poor performance of the fuel cell stack is caused by the air flow through the air flow determination sequence.

[0114] When E_TT ≥ T1, it means that the current coolant temperature deviation of the fuel cell stack from the target temperature is large; when EC_TT ≥ T2, it means that the current coolant temperature fluctuation of the fuel cell stack is large. When both E_TT ≥ T1 and EC_TT ≥ T2 are satisfied, it indicates that the poor performance of the fuel cell stack at this time is caused by the coolant temperature, that is, the poor performance of the fuel cell is not caused by the deterioration of the fuel cell stack performance. At this time, it is not necessary to perform the preset performance protection operation on the fuel cell stack of the fuel cell, and only need to return to the voltage determination sequence, and then protect the performance of the fuel cell by adjusting the coolant temperature and detecting the performance of the fuel cell in real time through the voltage determination sequence.

[0115] Further, when it is determined that the poor performance of the stack is not caused by the coolant temperature and the air flow needs to be determined, the air flow determination sequence adopted is as follows: Set the air flow deviation threshold as F1 and the air flow deviation rate threshold as F2; when E_F < F1, it indicates that the current air flow deviation target temperature of the stack is small; when EC_F < F2, it indicates that the current air flow fluctuation is small. When both E_F < F1 and EC_F < F2 are satisfied, it means that the poor performance of the stack at this time is not caused by the air flow, but by the decline of the stack's own performance, excluding the interference of the air flow factor.

[0116] Further, when E_F ≥ F1, it indicates that the current air flow deviation target temperature of the stack is large; when EC_F ≥ F2, it indicates that the current air flow fluctuation is large. When both E_F ≥ F1 and EC_F ≥ F2 are satisfied, it means that the poor performance of the stack at this time is caused by the air flow. Therefore, switch from the air flow determination sequence to the coolant temperature determination sequence to protect the battery performance by adjusting the air flow.

[0117] Step 303: When it is determined that the performance of the stack of the fuel cell has declined, perform a preset performance protection operation on the stack and stop performing the performance protection operation according to the voltage deviation parameter.

[0118] Specifically, when it is determined through the coolant temperature determination sequence and the air flow determination sequence that the poor performance of the stack is not caused by the coolant temperature and air flow factors, but by the decline of its own performance, perform performance protection on the stack according to the preset execution processing sequence. Among them, in some real-time modes of this embodiment, an execution processing sequence is provided as Figure 5 shown, mainly including:

[0119] S1: Increase the air excess coefficient of the cathode of the stack. Among them, the air excess coefficient is increased by N times on the original basis;

[0120] S2: Increase the throttle opening of the cathode of the stack and maintain the target pressure at the air inlet of the stack unchanged;

[0121] S3: Increase the hydrogen pump speed of the anode of the stack;

[0122] S4: Shorten the opening period of the hydrogen tail discharge valve at the anode of the stack;

[0123] S5: Increase the target temperature at the coolant inlet of the stack for a short time.

[0124] Through steps S1 to S5, the performance of the fuel cell stack is protected from three aspects: the cathode, the anode, and the coolant. Among them, in terms of the cathode, increasing the air excess coefficient is equivalent to increasing the air flow rate, which speeds up the discharge of excess moisture at the cathode. And increasing the throttle opening to maintain the air inlet pressure of the fuel cell stack ensures that the amount of hydrogen reactants at the anode remains unchanged; in terms of the anode, increasing the hydrogen pump speed and shortening the hydrogen tail gas discharge valve cycle speeds up the discharge of moisture at the anode; in terms of the coolant, raising the coolant temperature increases the conversion of water into water vapor, which is conducive to discharge.

[0125] Furthermore, during the performance protection operation of the fuel cell stack, the voltage deviation parameter of the fuel cell stack is obtained in real time, and the second threshold of the voltage deviation rate is set as U3. Among them, U3 is less than U2.

[0126] When E_U < U1 indicates that the current fuel cell stack voltage deviation from the target voltage is small and EC_U > U3 indicates that the current voltage fluctuation is small, the execution processing sequence is switched to the voltage determination sequence to perform the performance evaluation of the fuel cell for the next moment after the protection performance.

[0127] A performance protection method for a fuel cell without CVM provided in this embodiment can calculate the voltage deviation and the deviation change rate in real time when the performance of the fuel cell system deteriorates and there is no CVM device, detect the performance deterioration of the fuel cell in a timely manner, trigger relevant operating conditions to identify the reasons for the performance deterioration, and adopt corresponding performance protection operations to change the performance deterioration situation, thereby improving the performance of the fuel cell stack, avoiding the continued occurrence of single low and reverse polarization, and achieving the purpose of extending the life.

[0128] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. In particular, for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A performance protection method for a CVM-free fuel cell, characterized in that: include: Collecting the stack voltage value, coolant inlet temperature value and air flow value of the fuel cell to obtain the stack voltage deviation parameter, coolant inlet temperature deviation parameter and air flow deviation parameter of the fuel cell; Performing performance determination on the fuel cell based on the stack voltage deviation parameter, the coolant inlet temperature deviation parameter and the air flow deviation parameter to obtain a performance state of the fuel cell; When the performance state is in a declining state, a preset performance protection operation is performed on the fuel cell.

2. A performance protection method for a CVM-free fuel cell according to claim 1, characterized in that: The collecting of the fuel cell stack voltage value, the coolant inlet temperature value and the air flow value includes: According to a preset detection cycle, obtaining a first voltage value of the fuel cell stack corresponding to the beginning of each detection cycle and a second voltage value corresponding to the end of the detection cycle; Obtaining a first temperature value corresponding to the coolant inlet of the stack at the beginning of each detection cycle and a second temperature value corresponding to the end of each detection cycle; A first air flow value of an air inlet of the fuel cell stack in a detection cycle before a current detection cycle and a second air flow value in a current detection cycle are obtained.

3. A performance protection method for a CVM-free fuel cell according to claim 2, characterized in that: The step of obtaining a fuel cell stack voltage deviation parameter, a coolant inlet temperature deviation parameter, and an air flow deviation parameter includes: Obtaining the current density of the fuel cell in each detection cycle to obtain the standard voltage value, standard temperature value and standard air flow value of the fuel cell stack under the current density; Acquire a first voltage deviation value between the first voltage value and the standard voltage value and a second voltage deviation value between the second voltage value and the standard voltage value, so as to use the difference between the first voltage deviation value and the second voltage deviation value as a voltage deviation rate value of the fuel cell in a current detection cycle; Acquire a first temperature deviation value between the first temperature value and the standard temperature value and a second temperature deviation value between the second temperature value and the standard temperature value, so as to use the difference between the first temperature deviation value and the second temperature deviation value as a temperature deviation rate value of the fuel cell in a current detection cycle; A first air flow deviation value between the first air flow value and the standard air flow value and a second air flow deviation value between the second air flow value and the standard air flow value are obtained, so as to use the difference between the first air flow deviation value and the second air flow deviation value as the air flow deviation rate value of the fuel cell in the current detection cycle.

4. A performance protection method for a CVM-free fuel cell according to claim 3, characterized in that: The step of obtaining the performance status of the fuel cell by performing performance determination on the fuel cell includes: evaluating the performance state of the fuel cell according to a preset voltage deviation threshold and a preset first voltage deviation rate threshold; When the first voltage deviation value is greater than the voltage deviation threshold, the second voltage deviation value is greater than the voltage deviation threshold, and the voltage deviation rate value is greater than the first voltage deviation rate threshold, it is determined that the performance state of the fuel cell is in a declining state.

5. A performance protection method for a CVM-free fuel cell according to claim 4, characterized in that: The step of determining the performance of the fuel cell and obtaining the performance status of the fuel cell includes: When it is determined that the performance state of the fuel cell is in a declining state, the reason for the performance decline of the fuel cell is obtained based on the first temperature deviation value, the second temperature deviation value, the temperature deviation rate value, the first air flow deviation value, the second air flow deviation value and the air flow deviation rate value of the fuel cell stack.

6. A performance protection method for a CVM-free fuel cell according to claim 5, characterized in that: The obtaining of the reason for the performance degradation of the fuel cell includes: When the first temperature deviation value is greater than or equal to a preset temperature deviation threshold, the second temperature deviation value is greater than or equal to the temperature deviation threshold, and the temperature deviation rate value is greater than or equal to a preset temperature deviation rate threshold, determining that the coolant temperature is the cause of the performance degradation of the fuel cell; When the first temperature deviation value is less than the temperature deviation threshold, the second temperature deviation value is less than the temperature deviation threshold, the temperature deviation rate value is less than the preset temperature deviation rate threshold, and the first air flow deviation value is greater than or equal to the preset air flow deviation threshold, the second air flow deviation value is greater than or equal to the air flow deviation threshold, and the air flow deviation rate value is greater than or equal to the preset air flow deviation rate threshold, it is determined that the air flow is the cause of the performance degradation of the fuel cell.

7. A performance protection method for a CVM-free fuel cell according to any one of claims 1 to 6, characterized in that: The performing a preset performance protection operation on the fuel cell includes: When the first air flow deviation value is less than a preset air flow deviation threshold, the second air flow deviation value is less than the air flow deviation threshold, and the air flow deviation rate value is less than the preset air flow deviation rate threshold, it is determined that the performance degradation of the fuel cell stack is caused by the performance degradation of the fuel cell and a preset performance protection operation is performed on the fuel cell.

8. A performance protection method for a CVM-free fuel cell according to claim 7, characterized in that: The performing a preset performance protection operation on the fuel cell includes: Increase the air flow and throttle opening of the stack cathode, and keep the target pressure at the stack air inlet unchanged; Increasing the speed of the hydrogen pump of the anode of the stack and shortening the opening period of the hydrogen tail exhaust valve of the anode of the stack; The temperature of the coolant inlet of the stack is increased.

9. A performance protection method for a CVM-free fuel cell according to claim 8, characterized in that: The performing a preset performance protection operation on the fuel cell includes: When the first voltage deviation value is less than or equal to a preset voltage deviation threshold, the second voltage deviation value is less than or equal to the voltage deviation threshold, and the voltage deviation rate value is greater than a preset second voltage deviation rate threshold, the performance protection operation is stopped.

10. A performance protection system for a CVM-free fuel cell, characterized in that: Including data acquisition module, performance evaluation module and performance protection module; The data acquisition module is used to collect the stack voltage value, coolant inlet temperature value and air flow value of the fuel cell to obtain the stack voltage deviation parameter, coolant inlet temperature deviation parameter and air flow deviation parameter of the fuel cell; The performance evaluation module is used to determine the performance of the fuel cell according to the stack voltage deviation parameter, the coolant inlet temperature deviation parameter and the air flow deviation parameter, and obtain the performance status of the fuel cell; The performance protection module is used to perform a preset performance protection operation on the fuel cell when the performance state is in a declining state.

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