Spectral analysis of input currents of delta PWM converters using discrete Fourier transform

The authors present the input current harmonic analysis of delta-modulated converters. The analysis is based on the discrete Fourier transform of sampled input current waveforms of various converters. The converter configurations considered include the AC-AC voltage controller, the controlled rectifier, and inverters. The use of the discrete Fourier transform in waveform analysis is associated with spectral leakage and aliasing. To minimize these effects, the use of proper windows to weight the sampled waveforms is examined. Sampled waveforms are windowed by three different windows, namely the Hamming, the Hanning, and the Blackman window. The results obtained in the study were experimentally verified