Time-frequency analysis of complex space-phasor in power electronics

This paper considers applying Wigner distribution and min-norm method (subspace method) with sliding window, for calculation time-frequency representation of non-stationary signals in power electronics. Space-phasor was used as a complex representation of 3-phase signal in order to calculate spectrum of positive and negative-sequence. The proposed methods were tested with nonstationary multiple-component signals occurring during the fault operation of inverter-fed drive. Time and frequency resolution and phase dependence of the tested methods were investigated and compared with the parameters of the frequency estimation via FFT.