Probabilistic Approach for the Study of Neutral Current Ripple in Split-Capacitor Inverters

This paper presents a novel approach based on random variable algebra to study the neutral current ripple in three-phase four-wire split-capacitor inverters. The proposed method provides a more intuitive way of understanding and quantifying current ripple cancellations occurring on the neutral wire. Furthermore, thanks to its more straightforward approach, the extension over the whole modulation index range of neutral current ripple RMS in the case of interleaved PWM is presented. Finally, a comprehensive analysis of the neutral current ripple RMS in the case of unevenly displaced PWM carriers is also discussed. All the developments are validated by employing numerical results tested over various operating conditions.