SYSTEM AND METHOD FOR ESTIMATING IMPEDANCE IN ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY

摘要

The method for estimating impedance in electrochemical impedance spectroscopy is an iterative method, combining high order statistic (HOS) deconvolution and adaptive filtering (AF) to estimate impedance in electrochemical impedance spectroscopy for such applications as measuring the degree of electrolytic corrosion in a coated metal pipe, for example.

主权项

1. A method for estimating impedance in electrochemical impedance spectroscopy, comprising the steps of:
(a) establishing an initial estimate of resistance of an electrolytic solution RS0, an initial estimate of impedance z0, an initial estimate of voltage v0, an initial estimate of capacitance of a coating of a piece of coated metal Cc0, an initial estimate of a polarization resistance of an interface between the electrolytic solution and the piece of coated metal Rpo0, an initial estimate of a charge transfer resistance at the interface between the electrolytic solution and the piece of coated metal Rct0, and an initial estimate of double-layer capacitance at the interface between the electrolytic solution and the piece of coated metal Cdl0; (b) setting an integer i equal to zero; (c) calculating an i-th estimate of the resistance of the electrolytic solution RSi asRSi=RSi-1+μ(vi-1-Ii-1zi-1)Ii·δzi-1*δRSi-1,where μ is a pre-set step size, vt is an i-th estimate of voltage, I is an i-th estimate of current, and zi is an i-th estimate of impedance;
(d) setting vi-1 equal to a measured voltage across the coating and calculating an i-th estimate of the capacitance of the coating Cci asCci=Cci-1+μ(vi-1-Ii-1zi-1)Ii·δzi-1*δCci-1; (e) setting Ii-1 equal to a current measured at the interface between the electrolytic solution and the piece of coated metal and calculating an i-th estimate of the polarization resistance of the interface between the electrolytic solution and the piece of coated metal Rpoi asRpoi=Rpoi-1+μ(vi-1-Ii-1zi-1)Ii·δzi-1*δRpoi-1; (f) setting vi-1 equal to a voltage across a corroded portion at the interface between the electrolytic solution and the piece of coated metal and calculating an i-th estimate of the double-layer capacitance at the interface Cdli asCdli=Cdli-1+μ(vi-1-Ii-1zi-1)Ii·δzi-1*δCdli-1; (g) calculating an i-th estimate of the charge transfer resistance at the interface Rcti asRcti=Rcti-1+μ(vi-1-Ii-1zi-1)Ii·δzi-1*δRcti-1; (h) calculating an i-th estimate of a weight vector wi aswi=qjCciRpoi[(δzδRpoi)-2-1]; (i) calculating the i-th estimate of the impedance aszi=RSi+Rcti1+jwiRctiCdli;and
(j) if |zi−zi-1| is greater than a pre-set threshold, then setting i=i+1 and returning to step (c); otherwise, saving zi in non-transitory computer readable memory and displaying zi.