Efficient analytical modeling for pulsed eddy current signals using adaptive interpolation-based Fourier transform

In the analytical modelling for pulsed eddy current (PEC) signals based on the Fourier transform, there is a computational burden caused by calculating hundreds of harmonic impedance changes. In this paper, an adaptive interpolation method that takes inflection points as the initial interpolation nodes is proposed for calculating harmonic impedance changes. The inflection points of impedance change with frequency are deduced from the transformer model to divide the initial interval of interpolation. In the process of the adaptive interpolation method, it is necessary to divide the subintervals which fail to meet the requirements of interpolation accuracy, and then calculate the harmonic impedance changes by the cubic spline interpolation method. The adaptive interpolation method was verified by the simulation and experimental results. The results show that the adaptive interpolation method interpolates hundreds of harmonic impedance changes with dozens of interpolation nodes. There is a good agreement between the experimental PEC signals and the PEC signals obtained by the adaptive interpolation method, and the relative errors of the peak values are about 0.1%.