A new approach to the estimation of harmonics of digitized periodic waveforms

An approach to improving the accuracy in the determination of harmonic components in nonsynchronously sampled power convertor waveforms over a single period is introduced. A window, the trapezoidal compensating window (TCW), whose main lobe varies with the signal period, is used, thus minimizing long term leakage effects. The first side lobe crossing, being close to the first harmonic, minimizes medium-range leakage effects. Short-term leakage is reduced by a discrete Fourier series type computation scheme which evaluates the harmonic components at the actual frequencies. This window is compared with some commonly used types using two distorted signals.