Discontinuous Quasi-2-Level Modulation for MV applications

Inhalt:
The concept of Quasi-2-Level (Q2L) modulation is a potential alternative to series-connected semiconductors with bulky passive snubber as well as complex multilevel converters in medium voltage (MV) domain. The key idea is to operate a multilevel converter in a 2–level manner with a brief delay between switching the series-connected semiconductors. This approach allows to ensure equal voltage distribution between the switches and to minimize the system size by utilizing smaller capacitors. On the other hand, the number of series-connected switches in Q2L converters limits the maximum switching frequency. This study shows the advantages of discontinuous Q2L (DQ2L) modulation to increase these limits. The experimental results demonstrate that the DQ2L increases the switching frequency limitations. Furthermore, the capacitor current rms is reduced by 37% when the DQ2L is employed.