Flat-top windows for PWM waveform processing via DFT

New flat-top windows by which per forming the measurement of the parameters that characterise periodic signals are presented. It is shown how, by applying these windows in the frequency domain beyond the FFT, the negative effects of both the spectral leakage and the harmonic interference are reduced without employing interpolation algorithms. The high accuracy of the results is confirmed by an error analysis. These windows are very useful in the determination of the harmonic content of the inverter output PWM waveforms supplying electrical motors, in order to qualify the entire drive.