Monitoring of Inverter Drives in Time-Frequency Domain

This paper proposes to apply the Wigner-Ville distribution (WVD) or, alternatively, a "new" time-frequency representation (TFR) to voltage and current signals of inverter drives to monitor instantaneous complex power, voltage and current space-vectors in the time-frequency domain. The WVD and TFR satisfy the following properties: the frequency integral is the instantaneous power and the time integral is the spectral energy distribution. Therefore, both techniques are powerful mathematical tools to describe the behaviour of inverter drives and that of unbalanced and non-sinusoidal three-phase systems. The new TFR is preferable because shows correct information about the frequency locations of the spectral components, while the WVD does not. We show the results of applying the new time frequency representation.