A Novel One-Dimension Space Vector Strategy for Multilevel Cascaded Inverters

This paper presents a novel one-dimension space vector (NODSV) strategy with common-mode voltage (CMV) attenuation and optimal line-to-line voltage harmonic spectrum for the multilevel cascaded inverter. The principle of the proposed method is analyzed in terms of CMV and line-to-line voltage harmonic spectrum. Compared with the conventional unipolar modulation method, the proposed NODSV limits the CMV magnitude to the range of
$\boldsymbol{V}_{\mathbf{dc}}/\boldsymbol{3}$
without sacrificing the line-to-line voltage harmonic spectrum. The high-frequency harmonics in the CMV are much lower than those of the conventional modulation scheme. Furthermore, the proposed modulation method achieves a power balance between power semiconductor devices of the cascaded inverter and eliminates the dead-time effect, and the power loss is 30% lower than that of the conventional modulation scheme in the simulation results. Finally, the experimental results validate the total harmonic distortion (THD) of line-to-line voltage is reduced from 45.11% to 40.89%. The proposed NODSV method is an effective trade-off solution to reduce CMV without sacrificing the line-to-line voltage harmonic spectrum.