Device and method for diagnosing air flow of fuel cell

Abstract

The invention relates to the technical field of fluid measurement and diagnosis, in particular to a diagnosis device and method for the air flow of a fuel cell, and the method comprises the steps: carrying out a multi-working-condition test before an air compressor leaves a factory, and building a standard characteristic map of the rotation speed-pressure ratio-flow of the air compressor; then, the rotating speed, inlet and outlet pressure, temperature and actual flow data of an air compressor are collected in real time in the operation process of the fuel cell system, the theoretical flow under the standard working condition is obtained by calculating the pressure ratio and inquiring the atlas, and meanwhile the actually-measured flow is converted into the standard working condition; finally, whether the air flow meter is abnormal or not is judged by comparing whether the deviation between the theoretical value and the converted actual value exceeds a threshold value or not, and therefore online real-time diagnosis and fault alarm of the flow meter are achieved. According to the invention, no extra hardware needs to be added, high-precision non-intrusive diagnosis can be realized only through a software algorithm and pre-stored data, and the reliability and maintenance efficiency of the fuel cell system are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of fluid measurement and diagnostic technology, and specifically to a diagnostic device and method for air flow rate in a fuel cell. Background Technology

[0002] Against the backdrop of the world's active promotion of sustainable energy development, fuel cells, as a highly efficient and clean energy conversion device, are receiving widespread attention and in-depth research, and are gradually being applied in many fields, such as new energy vehicles and distributed power generation systems.

[0003] In fuel cell systems, air acts as an oxidant in electrochemical reactions, providing the necessary oxygen to the system. Precise control and monitoring of airflow plays a decisive role in optimizing the performance, maintaining stability, and improving the durability of fuel cell systems.

[0004] Flow rate is usually measured directly by sensors, but sensors are easily contaminated by impurities in the air during long-term use, which reduces the measurement accuracy. In addition, pipe bends, flow meter filter blockage, or positional misalignment can all cause deviations in flow measurement. Currently, there is a lack of real-time verification function for air flow measurement values. When it is uncertain whether the flow rate is accurate, the only way to check is to disassemble the pipeline and install a new flow meter for calibration.

[0005] Therefore, developing an accurate and reliable airflow diagnostic method is of great practical significance and urgent need for timely detection and resolution of airflow-related problems in fuel cell systems, ensuring stable and efficient system operation. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the background art by proposing a diagnostic device and method for air flow in fuel cells.

[0007] The technical solution of the present invention: a method for diagnosing the air flow rate of a fuel cell, comprising the following specific implementation steps: Establish a standard characteristic graph of air compressor speed-pressure ratio-flow rate under standard operating conditions; Real-time data collection of air compressor speed, intake pressure, exhaust pressure, intake temperature, and measured air mass flow rate; Based on the rotational speed and the calculated pressure ratio, a pre-stored standard characteristic spectrum is consulted to obtain the theoretical airflow under standard operating conditions; Based on the measured air mass flow rate, intake pressure, and intake temperature, the converted mass flow rate under standard operating conditions is calculated. The theoretical airflow rate is compared with the equivalent mass flow rate. If the deviation between the two exceeds a preset threshold, the airflow meter is determined to be abnormal and an alarm signal is issued.

[0008] Preferably, the process for constructing the standard characteristic spectrum of speed-pressure ratio-flow rate is as follows: Preheating is performed when the air compressor is unloaded; Adjust the exhaust pressure under different operating conditions, and collect data on air compressor speed, intake flow rate, intake pressure, exhaust pressure, intake temperature, exhaust temperature, and motor power; The collected data is corrected to standard operating conditions to form the corresponding relationship graph of speed-pressure ratio-flow rate.

[0009] Preferably, the pressure ratio is calculated by the ratio of exhaust pressure to intake pressure.

[0010] Preferably, the equivalent mass flow rate is: ; in, P represents the reduced mass flow rate; ref T represents the standard pressure under reference standard conditions; ref This indicates the standard temperature under reference standard conditions; P represents the measured mass flow rate. in T is the air compressor intake pressure. in This refers to the air compressor intake temperature.

[0011] Preferably, the standard pressure is 101.325 kPa and the standard temperature is 273.15 K.

[0012] Preferably, the deviation is: ; in, For deviation; This is the theoretical airflow rate.

[0013] The technical solution of the present invention: a diagnostic device for fuel cell air flow, which is used to perform the above-mentioned diagnostic method for fuel cell air flow, comprising: The sensor array is used to collect real-time data on air compressor speed, intake pressure, exhaust pressure, intake temperature, and measured air mass flow rate. The control unit is used to store the standard characteristic spectrum and calculate the theoretical flow rate, equivalent flow rate and deviation based on real-time data, and to perform fault diagnosis. The alarm module is used to issue alarm signals when abnormalities are diagnosed.

[0014] Preferably, the sensor group includes: Speed ​​sensor; Intake pressure sensor and exhaust pressure sensor; Intake air temperature sensor; Air flow meter.

[0015] Preferably, the control unit is an electronic control unit (ECU) with built-in memory and processor.

[0016] Compared with the prior art, the above-mentioned technical solution of the present invention has the following beneficial technical effects: This invention designs a diagnostic device and method for fuel cell air flow. The method compares the standard operating condition characteristic spectrum pre-stored by the air compressor with real-time operating data, and combines environmental parameter conversion calculations to achieve high-precision, online, and non-invasive diagnosis of fuel cell air flow meters. This method effectively eliminates the influence of ambient temperature and pressure fluctuations on flow measurement, significantly improving the accuracy and reliability of diagnostic results. It can promptly issue alarms when flow meter deviations occur, avoiding performance degradation or damage to fuel cells due to measurement distortion, extending system life, and reducing maintenance costs. At the same time, it requires no additional hardware, has strong compatibility, and is suitable for intelligent health management of various fuel cell systems. Attached Figure Description

[0017] Figure 1 This is a flowchart of a method for diagnosing the air flow rate of a fuel cell proposed in this invention; Figure 2 This is a schematic diagram of a diagnostic device for fuel cell air flow proposed in this invention. Detailed Implementation

[0018] Example 1, as Figure 1 As shown, the present invention proposes a method for diagnosing the air flow rate of a fuel cell, which includes the following specific implementation steps: S1. Before the air compressor leaves the factory, conduct multi-condition tests on a standard test bench to obtain the air compressor's characteristic data and curves. The specific steps are as follows: S11. Start-up and preheating: The air compressor runs under no-load conditions for a period of time to allow its components to reach a stable working state. S12. Data Acquisition: Under different operating conditions, gradually adjust the exhaust pressure of the air compressor and record the following parameters: air compressor speed, intake flow rate, intake pressure, exhaust pressure, intake temperature, exhaust temperature, and motor power. Each operating point needs to run stably for a period of time to ensure data accuracy; S13. Multi-condition test: Change parameters such as intake pressure and intake temperature in sequence, repeat the above data acquisition process, and obtain performance data under different operating conditions. S14. Data Correction: Correct the actual test data to standard operating conditions (temperature 273.15K, pressure 101.325kPa), generate a graph showing the correspondence between air compressor speed, pressure ratio, and flow rate, and store it.

[0019] S2. During the operation of the fuel cell system, the following data are collected in real time through a sensor network: air compressor speed signal, air compressor intake pressure P in and exhaust pressure P out Air compressor inlet temperature T in Measured mass flow rate .

[0020] S3. Based on the real-time collected air compressor speed and pressure ratio: Query the pre-stored air compressor characteristic graph from step S1 to obtain the theoretical air flow rate under standard operating conditions. .

[0021] S4. Because the actual flow rate is affected by environmental conditions, it needs to be corrected to standard operating conditions for comparison with the theoretical flow rate. The formula for calculating the equivalent flow rate is as follows: ; in, P represents the equivalent mass flow rate (standard operating conditions); ref This represents the pressure under reference standard conditions, i.e., 101.325 kPa; T ref This indicates the temperature under reference standard conditions, i.e., 273.15K.

[0022] S5. The theoretical airflow rate obtained in step S3 Compared with the equivalent actual flow rate calculated in step S4 Compare them and calculate their deviation values. : ; If the deviation exceeds the preset threshold (e.g., 5%), the flow meter is determined to be abnormal and an alarm signal is immediately issued, indicating that maintenance or replacement is required.

[0023] Example 2, as Figure 2 As shown, the present invention proposes a diagnostic device for fuel cell air flow, which is used to execute a diagnostic method for fuel cell air flow proposed in Embodiment 1, comprising: (1) Sensor group: Construct a sensor network for real-time acquisition of system operation data, including: Speed ​​sensor: monitors the speed of the air compressor; Pressure sensors: Installed at the inlet and outlet ends of the air compressor, respectively, to measure the inlet pressure P. in and exhaust pressure P out (Used to calculate pressure ratio); Temperature sensor: Installed at the air inlet of the air compressor to measure the inlet air temperature T. in ; Air flow meter: Used to measure the actual air mass flow rate (i.e., the object being diagnosed). (2) Control unit (e.g., ECU): This is the brain of the device, with built-in memory and processor, responsible for performing the following core functions: Data storage: Pre-stored air compressor characteristic charts measured by the air compressor manufacturer on a standard test bench (the charts establish the correspondence between air compressor speed, pressure ratio and output flow under standard operating conditions); Theoretical flow rate calculation: Based on the real-time collected speed and pressure ratio signals, the pre-stored characteristic spectrum is consulted to obtain the theoretical air flow rate value under the current operating conditions. ; Actual flow rate conversion calculation: Received flow rate measured by the flow meter And the intake P in and T in The flow rate is converted to the standard operating condition value using a formula. This is to eliminate the influence of environmental factors and facilitate fair comparison; Diagnosis and Decision Making: Theoretical Flow and the converted actual flow rate If the two are compared and the deviation exceeds a preset threshold, the flow meter measurement is determined to be abnormal. (3) Alarm module: Receives instructions from the control unit and issues an audible, visual or electrical alarm when a fault is diagnosed to alert maintenance personnel.

[0024] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for diagnosing air flow rate in a fuel cell, characterized in that, The specific implementation steps include the following: Establish a standard characteristic graph of air compressor speed-pressure ratio-flow rate under standard operating conditions; Real-time data collection of air compressor speed, intake pressure, exhaust pressure, intake temperature, and measured air mass flow rate; Based on the rotational speed and the calculated pressure ratio, a pre-stored standard characteristic spectrum is consulted to obtain the theoretical airflow under standard operating conditions; Based on the measured air mass flow rate, intake pressure, and intake temperature, the converted mass flow rate under standard operating conditions is calculated. The theoretical airflow rate is compared with the equivalent mass flow rate. If the deviation between the two exceeds a preset threshold, the airflow meter is determined to be abnormal and an alarm signal is issued.

2. The method for diagnosing the air flow rate of a fuel cell according to claim 1, characterized in that, The process of constructing the standard characteristic spectrum of speed-pressure ratio-flow rate is as follows: Preheating is performed when the air compressor is unloaded; Adjust the exhaust pressure under different operating conditions, and collect data on air compressor speed, intake flow rate, intake pressure, exhaust pressure, intake temperature, exhaust temperature, and motor power; The collected data is corrected to standard operating conditions to form the corresponding relationship graph of speed-pressure ratio-flow rate.

3. The method for diagnosing the air flow rate of a fuel cell according to claim 2, characterized in that, The pressure ratio is calculated by the ratio of exhaust pressure to intake pressure.

4. The method for diagnosing the air flow rate of a fuel cell according to claim 3, characterized in that, The equivalent mass flow rate is: ； in, P represents the reduced mass flow rate; ref T represents the standard pressure under reference standard conditions; ref This indicates the standard temperature under reference standard conditions; P represents the measured mass flow rate. in T is the air compressor intake pressure. in This refers to the air compressor intake temperature.

5. The method for diagnosing the air flow rate of a fuel cell according to claim 4, characterized in that, The standard pressure is 101.325 kPa; the standard temperature is 273.15 K.

6. The method for diagnosing the air flow rate of a fuel cell according to claim 5, characterized in that, The deviation is: ； in, For deviation; This is the theoretical airflow rate.

7. A diagnostic device for fuel cell air flow, used to perform a diagnostic method for fuel cell air flow according to any one of claims 1 to 6, characterized in that, include: The sensor array is used to collect real-time data on air compressor speed, intake pressure, exhaust pressure, intake temperature, and measured air mass flow rate. The control unit is used to store the standard characteristic spectrum and calculate the theoretical flow rate, equivalent flow rate and deviation based on real-time data, and to perform fault diagnosis. The alarm module is used to issue alarm signals when abnormalities are diagnosed.

8. The diagnostic device for fuel cell air flow according to claim 7, characterized in that, The sensor group includes: Speed ​​sensor; Intake pressure sensor and exhaust pressure sensor; Intake air temperature sensor; Air flow meter.

9. The diagnostic device for fuel cell air flow according to claim 7, characterized in that, The control unit is an electronic control unit (ECU), with built-in memory and processor.

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