Fuel cell impedance measurement and analysis system and method based on key frequency points

Abstract

The invention, which belongs to the technical field of fuel cells, discloses a fuel cell impedance measurement and analysis system and method based on key frequency points. The system is characterizedin that a signal generation unit is used for enabling a sinusoidal signal generator to generate three key sinusoidal signals with different frequencies according to a detection sequence; a signal acquisition unit is used for collecting a stack voltage, a stack current and a monomer voltage; the input terminal of a signal detection and analysis unit is used for receiving the collected stack voltage, stack current and monomer voltage to calculate the impedance of a fuel cell stack and the impedance of a single fuel cell; a control unit is used for determining the internal state of the fuel cellaccording to output of the signal detection analysis unit. The internal state of the fuel cell is determined according to the impedance of the output key frequency point of the signal detection and analysis unit, and the real-time state of the fuel cell can be diagnosed by analyzing the signal of the key frequency. Compared with the traditional method, the disclosed method has the advantages of being higher in analysis rate and more complete in state information.

Description

technical field [0001] The invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell impedance measurement and analysis system and method based on key frequency points. Background technique [0002] At present, the closest existing technology: fuel cell has the characteristics of high conversion efficiency, environmental friendliness, and simple and flexible assembly. water removal, etc. Electrochemical impedance spectroscopy can separate the influence of different electrochemical processes on the fuel cell, and the internal state of the fuel cell can be inferred from the impedance information of the fuel cell, including: water content in the proton exchange membrane, liquid water content in the cathode, gas supply status, etc. In recent years, electrochemical impedance spectroscopy has become the main tool for fault diagnosis of fuel cell systems. [0003] The current online detection technology of fuel cell impedance is mainly reali...

AI Technical Summary

Problems solved by technology

However, the fixed-frequency measurement generally only selects a certain high-frequency signal value, and only calculates the value of the internal resistance of the fuel cell, which cannot fully interpret the state of the fuel cell.

[0004] In summary, the existing problems in the prior art are: (1) The current fuel cell impedance test method takes a long time and cannot measure the fuel cell impedance in time

[0005](2) The current fuel cell impedance test method adopts fixed frequency measurement and generally only selects a certain high frequency signal value, and only calculates the value of the internal resistance of the fuel cell. does not provide a comprehensive understanding of the state of the fuel cell

[0006] Difficulties in solving the above technical problems: 1) The real-time performance of the detection results is related to the frequency change of the signal generator and the data processing speed of the analysis unit. The frequency of the generator changes slowly, so it is difficult to achieve the real-time performance of the full frequency spectrum analysis method

2) There are many factors affecting the power generation state of the fuel cell, and the voltage and current of the battery fluctuate frequently, which is also difficult for signal processing

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