HYDROGEN FUEL CELL IMPEDANCE ESTIMATION BASED ON WAVELET TRANSFORM

Improving the efficiency and reliability of Proton Exchange Membrane Fuel Cells requires the development of on-line monitoring and diagnostics means. In the paper a method of electrochemical impedance estimation based on continuous wavelet transformation using Morse wavelet is proposed. The advantage of this approach is the possibility for better matching the probing signals and the impedance frequency characteristics under consideration from the point of view of frequency-time resolution. The high precision the frequency characteristics of impedance estimation in the frequency range of 0.1…100 Hz is achieved using a probing signal in the form of rectangular pulses with a total duration 2…10 s. It is established that sequences of rectangular pulses and other signals with similar spectral composition can be used as a probing signal. The analysis of influence the measuring equipment’s intrinsic noise on the accuracy of impedance estimation was carried out. The results of the analysis showed that is possible to implement an evaluation system on commercially available measuring amplifiers. The practical significance of the obtained results is the possibility of extending the functional and operational characteristics of the methods and devices of impedance monitoring of proton exchange membrane fuel cells when using both natural and artificial perturbations of the electrical operation mode of the fuel cell operation at a priori unknown moments of time.