Harmonic modeling of three-phase neutral-point inverters

The paper derives a closed-form analytical approximation of the output currents harmonic spectra for the three-phase neutral-point inverters under the action of hysteresis current control. The model is an extension of the recently developed model for single-phase two-level hysteresis inverters. The model derives the instantaneous frequency of the inverter and then uses it to approximate the error currents by frequency-modulated sinusoids. The spectra of the error currents are simply the Fourier transforms of the signals´ complex envelopes and are expressed in terms of Bessel functions of the first kind. The final expressions of the harmonic spectra are expressed in a suitable form for numerical calculations. MATLABSimulink^© studies are presented to validate the proposed model.