Analytical Technique for Predicting Harmonics Generated by Inverters Employing Naturally Sampled PWM

M. N. Gitau and G. Ebersohn (South Africa)


Analytic Solutions, PWM Techniques, Inverters, Harmonics, Switching Functions.


: Currently, almost all analytical techniques for predicting harmonics generated by inverters are based on the 3-dimensional modulation model [1-7] (geometrical wall model [7]) and the double Fourier series. However, this analytical technique is still not very easy to follow, as it requires several lengthy steps to determine coefficients of the double Fourier series. This paper presents a simpler yet accurate analytical technique to predict harmonics generated by inverters controlled using natural sampled PWM signals. It is shown that the proposed technique yields exactly the same results as those reported in [1,3-4, 6]. Analytical and experimental harmonic spectra for 3 kVA, 5 kHz, single-phase and 7.5 kVA, 5 kHz, three phase inverters are presented.

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