ACCURACY IMPROVEMENT OF THE ELECTROCHEMICAL POWER SOURCE IMPEDANCE MEASUREMENT METHOD BASED ON THE WAVELET ANALYSIS
E.S. Denisov1, Yu.K. Evdokimov1, O.V. Shindor2, K.V. Konkov1
1Kazan National Research Technical University named after A. N. Tupolev - KAI, Kazan, Russia
2Kazan Federal University, Kazan, Russia
Keywords: hydrogen energetics, proton exchange membrane fuel cell, electrochemical impedance, broadband signal, wavelet analysis, Morse wavelet, intrinsic noise of measuring equipment
Abstract
Providing efficient operation and increasing the reliability of proton exchange membrane fuel cells (PEMFCs) require new tools for real time monitoring of their technical condition that have small-amplitude disturbances of the current operating mode. Currently, one of the most informative small disturbance methods for studying PEMFCs is impedance spectroscopy. The use of the wavelet analysis and broadband probing signals can significantly reduce the analysis time and, as a result, increase the efficiency of making diagnostic decisions. However, the problem of a significant loss of accuracy in assessing high-frequency components of the impedance has been identified. Within the framework of this work, it has been determined that the reason for this is a significant contribution of high-frequency spectral components with a low signal-to-noise ratio, reaching 4 dB. A technique for threshold signal processing based on the wavelet transform is proposed, which makes it possible to increase the accuracy of assessing the amplitude-frequency characteristics of the impedance up to 0.3% in the frequency range of 0.1-400 Hz without increasing the signal-to-noise ratio. The proposed tools of high-precision assessment of impedance characteristics based on the wavelet analysis of broadband signals will find applications both in research laboratories and in real operating power plants based on PEMFCs.
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