Selective harmonic mitigation-pulse amplitude modulation technique for 7-level inverters.

This paper proposes a fundamental-switching-frequency selective harmonic mitigation method based on pulse amplitude modulation (PAM) that, in a single phase 7-level cascaded H-bridge inverter, reduces the amplitudes of all harmonics in the output voltage waveform, except those having order $n=16 k \pm 1, k=1,2,3, \ldots$. After explaining its mathematical formulation, the manuscript compares results obtained with the proposed method and those with a selective harmonic elimination pulse amplitude modulation. The results highlight the better filtering capability of the new approach. Further comparisons with a procedure based on the total harmonic minimization show that the new technique reduces two more low-order harmonics.