Voltage total harmonic distortion and related quadratic criteria are accepted as figures of merit of a multilevel PWM converter voltage quality. The dominating frequency domain voltage quality evaluation approach, in fact, is essentially numerical as it involves infinite double Fourier series expansion with Bessel function coefficients and requires high switching harmonics count. Suggested time domain approach for multilevel PWM converter voltage quality evaluation delivers simple piece-wise analytical solutions that clearly reveal the dependence on modulation index for an arbitrary number of voltage levels. The results are applicable to any type of multilevel converters with optimal nearest three space vector PWM allowing for fast comparative evaluation of voltage quality for filterless grid-connected converters with different levels count.
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