Reduction of Common-Mode Voltages for Five-Level Active NPC Inverters by the Space-Vector Modulation Technique

In this paper, a novel space-vector pulse-width modulation (PWM) scheme for reducing the common-mode voltage (CMV) in the three-phase five-level active neutral-point clamped (5L-ANPC) inverter is proposed, where only the 55 selected voltage vectors among the entire 125 that produce low values of the CMV are utilized. This PWM scheme can significantly reduce the CMV without the increase of switching losses and total harmonic distortion of the output voltages. With the 55 selected voltage vectors, the inverter can still operate up to the maximum modulation index. In addition, the capacitor voltages are controlled by redundant switches of the 5L-ANPC inverters. It has been shown that the peak value of the CMV is decreased to one-twelfth of the dc-link voltage from the simulation and experimental results.