A hydrogen energy stack partition EIS test system

Abstract

The application provides a hydrogen energy stack partition EIS test system, which comprises a partition detection plate assembly, a composite excitation source module, a multi-channel synchronous acquisition module and a central control and analysis module; the partition detection plate assembly is a multilayer PCB plate arranged in the stack, the surface of the PCB plate is etched with a real flow channel structure consistent with a bipolar plate of the stack, and a plurality of physical field sensors are embedded in the plate; the partition detection plate assembly physically separates the stack into a plurality of independent measured partitions; the composite excitation source module is directly connected to the partition detection plate assembly and used for applying a composite current signal to a specified measured partition; the multi-channel synchronous acquisition module is directly connected to each measured partition and the physical field sensors through circuit traces and probes arranged on the partition detection plate assembly and used for synchronously acquiring voltage responses, current responses and physical field data of each partition; and the central control and analysis module is in communication connection with the multi-channel synchronous acquisition module, receives the synchronously acquired data and generates spatial distribution information of the internal state of the stack.

Description

Technical Field

[0001] This invention relates to the field of fuel cell testing technology, and in particular to a hydrogen fuel cell stack zone EIS testing system. Background Technology

[0002] Health monitoring of fuel cells, especially proton exchange membrane fuel cells (PEMFCs), is crucial for ensuring their safe, reliable, and long-term operation. By embedding functionalized detection plates at specific locations within the fuel cell stack and matching them with a zoned EIS (Electrical Information System), processes such as ohmic losses, charge transfer, and mass transport within the cell can be non-invasively reflected, making it a key method for assessing its performance and health status. Currently, industry EIS testing solutions mainly revolve around overall stack impedance measurement, simplified monitoring based on voltage surveys, and auxiliary diagnostics combined with distributed sensors. These solutions have played a role in laboratory research and basic condition monitoring.

[0003] However, as fuel cell technology rapidly advances towards high-power, long stacks, and high-reliability automotive-grade applications, the complexity and non-uniformity of the spatial distribution of the internal state of the stack are becoming increasingly significant. Existing technologies are showing their inherent limitations when facing the demands of large-scale, sophisticated diagnostics. Current integrated EIS testing typically only acquires the total series impedance signal of the entire stack. When individual cells experience localized faults such as "flooding" or "membrane dryness," their abnormal impedance characteristics are easily masked by the average response of a large number of normal cells, leading to a severe "averaging effect." This makes it impossible to distinguish the state of individual cells or localized areas, resulting in missed early fault detection.

[0004] Furthermore, due to the lack of spatial dimension information, when the overall EIS spectrum changes, the diagnostic system struggles to accurately distinguish whether the change stems from an increase in ohmic impedance caused by membrane electrode drying, an increase in mass transfer impedance due to channel flooding, or a degradation of the kinetic process caused by catalyst aging. Faults of different locations and natures may coexist and superimpose, complicating the spectral characteristics. The analytical results based on the equivalent circuit model are often not unique, leading to blurred fault mechanism identification and an increased misjudgment rate.

[0005] Furthermore, existing diagnostic systems often isolate EIS electrical performance testing from the monitoring of the system's physical conditions such as temperature, humidity, and pressure, creating "data silos." The electrochemical processes inside the fuel cell stack are closely coupled with heat, water, and gas management. Single-dimensional electrical signal analysis cannot comprehensively and accurately reveal the root causes of condition degradation, limiting the depth and reliability of diagnostics.

[0006] In summary, existing EIS monitoring technologies are limited by core bottlenecks such as insufficient spatial resolution, ambiguous fault mechanism identification, and lack of multi-source data fusion, making it difficult to meet the industry's urgent needs for refined operation and maintenance, predictive health management, and life assessment of large-scale fuel cell stacks. Therefore, developing an online intelligent diagnostic system capable of achieving high-resolution zonal measurement, accurate mechanism identification, and multi-physics data fusion has become crucial for driving fuel cell technology from "passive response" to "active prediction," demonstrating significant technical necessity and engineering urgency. Summary of the Invention

[0007] To address the above issues, this invention achieves high-resolution EIS acquisition at the single-cell level, non-invasive stack-without segmentation, multi-physical quantity data fusion, and modular integrated design. This enables the precise construction of stack impedance spatial distribution maps, clear identification of fault mechanisms such as membrane dryness and flooding, and supports in-situ non-destructive deployment. It completely eliminates the averaging effect and mechanism ambiguity problems of traditional monitoring, significantly improving fault detection sensitivity and diagnostic accuracy. This provides key technical support for shifting fuel cells from passive maintenance to predictive maintenance.

[0008] According to an embodiment of the present invention, a zoned EIS testing system for hydrogen fuel cell stacks is provided. The system includes: The partition detection board assembly consists of a multilayer PCB board located inside the fuel cell stack. The surface of the PCB board is etched with a real flow channel structure consistent with the bipolar plates of the fuel cell stack, and several physical field sensors are embedded in the board. The partition detection board assembly physically divides the fuel cell stack into multiple independent test partitions. Composite excitation source module: It is directly connected to the partition detection board assembly and is used to apply a composite current signal to the specified partition under test; Multi-channel synchronous acquisition module: It is directly connected to each tested partition and the physical field sensor through circuit traces and probes on the partition detection board assembly, and is used to synchronously acquire the voltage response, current response and physical field data of each partition; Central control and analysis module: It is communicatively connected to the multi-channel synchronous acquisition module, receives the synchronously acquired data, and generates spatial distribution information of the internal state of the fuel cell stack.

[0009] Furthermore, the fuel cell stack consists of N units connected in series. Each unit is a single cell in the fuel cell stack and a single cell in the electrolyzer. The number of test zones is adjusted according to the size of the test object, and the maximum number of zones can be set to 300.

[0010] Furthermore, the PCB board can be placed on the end plate of the fuel cell stack or at any position on the fuel cell stack, and the flow channel structure connects the reaction gas inlet and the sensitive area of ​​the physical field sensor.

[0011] Furthermore, the physical field sensor is embedded in the flow channel of the PCB board and connected to the multi-channel synchronous acquisition module through traces integrated between the board layers.

[0012] Furthermore, the physical field sensor includes a temperature sensor and a humidity sensor encapsulated in the flow channel via thermally conductive silicone.

[0013] Furthermore, the composite current signal is composed of a frequency-adjustable sinusoidal alternating current superimposed on a constant DC bias current.

[0014] Furthermore, the central control and analysis module is configured to perform the following operations: Fourier transform is performed on the synchronously acquired voltage and current time-domain signals to calculate the complex impedance at each frequency point; The Nyquist plot is drawn based on the complex impedance, and an equivalent circuit model including ohmic impedance, charge transfer resistance and Warburg diffusion impedance is used for fitting. The overlapping impedance arcs were decoupled by distributed relaxation time analysis, and the membrane resistance characterizing proton conductivity, the charge transfer resistance characterizing catalyst activity, and the diffusion impedance characterizing mass transport state were extracted respectively.

[0015] Furthermore, the central control and analysis module is further configured to map at least one of the film resistance, charge transfer resistance, diffusion impedance and temperature and humidity data into a two-dimensional or three-dimensional cloud map reflecting the differences in their spatial distribution within the fuel cell stack.

[0016] Furthermore, the central control and analysis module is further configured to perform at least one of the following fault diagnoses by comparing the film resistance, charge transfer resistance, and diffusion impedance of different zones, and in conjunction with synchronously acquired temperature and humidity data: When the membrane resistance of a certain zone is significantly higher than that of the adjacent zone or the reference value, and the humidity reading of that zone is lower than the threshold, it is determined to be a membrane dryness fault. When the diffusion impedance of a certain zone increases sharply and the humidity reading of that zone is higher than the threshold, it is determined to be a flooding fault. When the charge transfer resistance of a certain region gradually increases over time, but the change in membrane resistance does not exceed the threshold, it is determined that the catalyst activity has declined.

[0017] This invention achieves high-resolution EIS acquisition at the single-cell level, non-invasive stack-without segmentation, multi-physical quantity data fusion, and modular integrated design. It can accurately construct the stack impedance spatial distribution spectrum, clearly identify fault mechanisms such as membrane dryness and water flooding, and support in-situ non-destructive deployment. It completely eliminates the averaging effect and mechanism ambiguity problems of traditional monitoring, significantly improves fault detection sensitivity and diagnostic accuracy, and provides key technical support for fuel cells to shift from passive maintenance to predictive maintenance.

[0018] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description.

[0019] The beneficial effects of this invention are: 1. This system can achieve fine impedance measurement from the stack level to the single cell level and even the sub-single cell level, and supports the synchronous acquisition of up to 300 zones. It completely eliminates the "averaging effect" in traditional overall impedance testing and significantly improves the sensitivity and spatial resolution of fault detection. 2. By integrating spatial distribution characteristics and multi-band impedance response characteristics, the system can clearly distinguish different physical failure modes such as membrane dryness, water flooding, and poor contact, effectively reducing the misjudgment rate caused by ambiguity in traditional methods. 3. The system deeply couples multi-source sensor data such as temperature, humidity, voltage, and impedance to construct a high-confidence multidimensional health assessment model, realizing the collaborative analysis and comprehensive diagnosis of electrochemical state and thermal / water management state; 4. It adopts an in-situ non-invasive design, which does not require modification of the fuel cell stack structure. Upgrades can be deployed using only the existing detection board, which greatly improves the convenience and feasibility of engineering implementation while ensuring diagnostic performance. 5. The product adopts a highly integrated modular design, featuring compact size, light weight, flexible installation, and simple wiring. It solves the pain points of traditional segmented monitoring solutions, which require the separation of key battery components, leading to stack structure damage and data distortion. Furthermore, it employs flexible circuitry and edge-lead design, requiring only a single-sided interface to complete signal acquisition for over 300 zones across the entire stack, eliminating the need for hundreds of independent wires in traditional solutions and significantly reducing assembly complexity and failure rate. For the first time, it achieves high-resolution, full-condition, online in-situ diagnostics without sacrificing stack performance and reliability. Attached Figure Description

[0020] The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. Wherein: Figure 1 A structural diagram of a hydrogen fuel cell stack partition EIS test system according to an embodiment of the present invention is shown; Figure 2 A schematic diagram of a partition detection board assembly according to an embodiment of the present invention is shown; Figure 3 A flowchart illustrating the data processing and diagnostic process of the central control and analysis module according to an embodiment of the present invention is shown; Figure 4 A cloud diagram of test results according to an embodiment of the present invention is shown. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] According to an embodiment of the present invention, a hydrogen fuel cell stack partitioned EIS testing system is proposed. By achieving high-resolution EIS acquisition at the single-cell level, non-invasive stack-segmentation, multi-physical quantity data fusion, and modular integrated design, it can accurately construct the stack impedance spatial distribution spectrum, clearly identify fault mechanisms such as membrane dryness and water flooding, and support in-situ non-destructive deployment. It completely eliminates the averaging effect and mechanism ambiguity problems of traditional monitoring, significantly improves fault detection sensitivity and diagnostic accuracy, and provides key technical support for fuel cells to shift from passive maintenance to predictive maintenance.

[0023] The principles and spirit of the present invention will be explained in detail below with reference to several representative embodiments.

[0024] Figure 1 This is a block diagram of a hydrogen fuel cell stack partition EIS testing system according to an embodiment of the present invention. The system includes: The partition detection board assembly consists of a multilayer PCB board located inside the fuel cell stack. The surface of the PCB board is etched with a real flow channel structure consistent with the bipolar plates of the fuel cell stack, and several physical field sensors are embedded in the board. The partition detection board assembly physically divides the fuel cell stack into multiple independent test partitions. Composite excitation source module: It is directly connected to the partition detection board assembly and is used to apply a composite current signal to the specified partition under test; Multi-channel synchronous acquisition module: It is directly connected to each tested partition and the physical field sensor through circuit traces and probes on the partition detection board assembly, and is used to synchronously acquire the voltage response, current response and physical field data of each partition; Central control and analysis module: It is communicatively connected to the multi-channel synchronous acquisition module, receives the synchronously acquired data, and generates spatial distribution information of the internal state of the fuel cell stack.

[0025] To provide a clearer explanation of the aforementioned hydrogen fuel cell stack partition EIS testing system, a specific embodiment will be used for illustration below. However, it is worth noting that this embodiment is only for better illustrating the present invention and does not constitute an improper limitation of the present invention.

[0026] The following example will be used to further illustrate a hydrogen fuel cell stack partition EIS testing system in more detail.

[0027] This embodiment uses a vehicle proton exchange membrane fuel cell stack with a rated power of 80kW as the test object.

[0028] The system in this embodiment is deployed in a fuel cell stack consisting of 300 individual cells connected in series. For example... Figure 1 As shown, the partition detection board assembly is inserted into the fuel cell stack, physically dividing it into 10 independent test partitions, each containing 30 individual cells connected in series. The partition detection board assembly is directly connected to the composite excitation source module and the multi-channel synchronous acquisition module via its board-side connectors and wiring harness; the multi-channel synchronous acquisition module is communicatively connected to the central control and analysis module.

[0029] The partition detection board assembly is a 1.6 mm thick PCB circuit board. Its surface is precision etched to create a serpentine flow channel structure perfectly identical to the graphite bipolar plate of the fuel cell stack, ensuring that insertion does not affect the normal distribution of reactant gases. Figure 2 As shown.

[0030] Physical field sensors are embedded at key locations in the flow channel of each partition. These include a temperature sensor using a thin-film platinum resistance thermometer and a humidity sensor using a capacitive polymer thin film. Both are encapsulated in grooves on the flow channel wall using thermally conductive silicone to ensure that their sensing parts are in full contact with the flowing hydrogen or air, enabling rapid response. The analog signal transmission lines of all sensors are designed within the inner layer of the printed circuit board to shield against external interference, and ultimately converge to a multi-pin high-speed connector at the edge of the board, connecting to a multi-channel synchronous acquisition module via a wiring harness.

[0031] The printed circuit board is mounted between the bipolar plate and the membrane electrode assembly, and the flow channel pattern on its surface ensures that the flow path from the gas inlet to the sensor sensitive area is completely unobstructed.

[0032] The incentive and data collection process is as follows: The central control and analysis module sets test tasks via a communication bus. For example, it performs an electrochemical impedance spectroscopy scan on one of the target zones.

[0033] The composite excitation source module receives instructions and applies a composite current signal to the target partition through connectors and dedicated traces on the printed circuit board. This signal is composed of an 80A DC bias current and a sinusoidal AC current with an amplitude of 8A and a frequency that gradually scans from 10kHz to 0.1Hz.

[0034] While applying excitation, the multi-channel synchronous acquisition module simultaneously acquires data at a sampling rate of 100 kS / s: it acquires the total current signal flowing through the target partition, the voltage signal at both ends of the target partition, and the output signals of the temperature and humidity sensors within the partition.

[0035] like Figure 3 As shown, the collected raw data is sent to the central control and analysis module for processing, and the process is as follows: First, impedance spectrum calculation is performed. A Fast Fourier Transform (FFT) is applied to the acquired voltage and current time-domain signals, and the complex impedance at each frequency point is calculated using Euler's formula. Taking one frequency point as an example, the complex impedance value at that frequency is obtained by calculating the amplitude ratio and phase difference between the voltage response and the current excitation. This process is repeated to obtain the complex impedance spectrum across the entire frequency range from 10 kHz to 0.1 Hz.

[0036] Next, equivalent circuit fitting and parameter extraction were performed. The impedance data of the target region were plotted as a Nyquist plot, and an equivalent circuit model incorporating ohmic impedance, charge transfer resistance, and Warburg diffusion impedance was used for fitting. Through high-precision fitting, the membrane resistance characterizing proton conductivity, the charge transfer resistance characterizing catalyst activity, and the diffusion impedance characterizing mass transport states were decoupled and extracted. Further distributed relaxation time analysis was used to separate overlapping impedance arcs in the mid-to-low frequency range, verifying the accuracy of the extracted parameters.

[0037] Then, multi-parameter fusion diagnosis and visualization are performed. The system automatically compares the characteristic parameters of all zones. For example, if the membrane resistance value of a zone is found to be significantly higher than that of its adjacent zones or historical reference values, and the humidity sensor reading of that zone is simultaneously lower than a set threshold, the system determines that the zone has a "membrane dryness" fault. If the Warburg diffusion impedance of a zone increases sharply and the humidity reading of that zone is saturated, it is determined to be a "flooding" fault. The system continuously records the historical data of charge transfer resistance of each zone. If it is found that the charge transfer resistance shows a monotonically increasing trend with operating time, while the membrane resistance remains stable, the zone is marked as having "catalyst activity decay". The system can map any one or more of the above membrane resistance, charge transfer resistance, diffusion impedance, and temperature and humidity data into a two-dimensional or three-dimensional cloud map that can intuitively reflect the differences in their spatial distribution inside the fuel cell stack, such as... Figure 4 As shown.

[0038] The system in this embodiment successfully achieves high-resolution positioning and precise mechanism identification of the internal state of the fuel cell stack. It can clearly distinguish different fault modes such as "membrane dryness" and "water flooding", and realizes the leap from fault diagnosis to health prediction. It effectively solves the problems of averaging effect, mechanism ambiguity and data silos in traditional monitoring methods.

[0039] While the spirit and principles of the invention have been described with reference to several specific embodiments, it should be understood that the invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that features in these aspects cannot be combined for benefit; such division is merely for ease of description. The invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0040] Regarding the limitation of the scope of protection of this invention, those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of this invention are still within the scope of protection of this invention.

Claims

1. A hydrogen fuel cell stack zone EIS testing system, characterized in that, The system includes: The partition detection board assembly consists of a multilayer PCB board located inside the fuel cell stack. The surface of the PCB board is etched with a real flow channel structure consistent with the bipolar plates of the fuel cell stack, and several physical field sensors are embedded in the board. The partition detection board assembly physically divides the fuel cell stack into multiple independent test partitions. Composite excitation source module: It is directly connected to the partition detection board assembly and is used to apply a composite current signal to the specified partition under test; Multi-channel synchronous acquisition module: It is directly connected to each tested partition and the physical field sensor through circuit traces and probes on the partition detection board assembly, and is used to synchronously acquire the voltage response, current response and physical field data of each partition; Central control and analysis module: It is communicatively connected to the multi-channel synchronous acquisition module, receives the synchronously acquired data, and generates spatial distribution information of the internal state of the fuel cell stack.

2. The hydrogen fuel cell stack zone EIS testing system according to claim 1, characterized in that, The fuel cell stack consists of N units connected in series. Each unit is a single cell in the fuel cell stack and a single cell in the electrolyzer. The number of test zones is adjusted according to the size of the test object, and the maximum number of zones can be set to 300.

3. The hydrogen fuel cell stack zone EIS testing system according to claim 1, characterized in that, The PCB board can be placed on the end plate of the fuel cell stack or at any position on the fuel cell stack, and the flow channel structure connects the reaction gas inlet and the sensitive area of ​​the physical field sensor.

4. The hydrogen fuel cell stack zone EIS testing system according to claim 3, characterized in that, The physical field sensor is embedded in the flow channel of the PCB board and is connected to the multi-channel synchronous acquisition module through traces integrated between the board layers.

5. The hydrogen fuel cell stack zone EIS testing system according to claim 4, characterized in that, The physical field sensor includes a temperature sensor and a humidity sensor encapsulated in the flow channel using thermally conductive silicone.

6. The hydrogen fuel cell stack zone EIS testing system according to claim 1, characterized in that, The composite current signal is composed of a frequency-adjustable sinusoidal alternating current superimposed on a constant DC bias current.

7. The hydrogen fuel cell stack zone EIS testing system according to claim 1, characterized in that, The central control and analysis module is configured to perform the following operations: The voltage and current time-domain signals acquired synchronously are subjected to Fourier transform, and the complex impedance at each frequency point is calculated by combining the Euler method. The Nyquist plot is drawn based on the complex impedance, and an equivalent circuit model including ohmic impedance, charge transfer resistance and Warburg diffusion impedance is used for fitting. The overlapping impedance arcs were decoupled by distributed relaxation time analysis, and the membrane resistance characterizing proton conductivity, the charge transfer resistance characterizing catalyst activity, and the diffusion impedance characterizing mass transport state were extracted respectively.

8. The hydrogen fuel cell stack zone EIS testing system according to claim 7, characterized in that, The central control and analysis module is further configured to map at least one of the film resistance, charge transfer resistance, diffusion impedance and temperature and humidity data into a two-dimensional or three-dimensional cloud map reflecting the differences in their spatial distribution inside the fuel cell stack.

9. A hydrogen fuel cell stack zone EIS testing system according to claim 7 or 8, characterized in that, The central control and analysis module is further configured to perform at least one of the following fault diagnoses by comparing the film resistance, charge transfer resistance, and diffusion impedance of different zones, and in conjunction with synchronously acquired temperature and humidity data: When the membrane resistance of a certain zone is significantly higher than that of the adjacent zone or the reference value, and the humidity reading of that zone is lower than the threshold, it is determined to be a membrane dryness fault. When the diffusion impedance of a certain zone increases sharply and the humidity reading of that zone is higher than the threshold, it is determined to be a water flooding fault. When the charge transfer resistance of a certain region gradually increases over time, but the change in membrane resistance does not exceed the threshold, it is determined that the catalyst activity has declined.

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