Two-level operation of a diode-clamped multilevel inverter

This paper presents space vector based quasi two-level operation of a diode-clamped multilevel inverter in an attempt to improve the dc link utilization and output voltage quality, and avoids dc link capacitor voltage balancing problems experienced with standard multilevel operation. Beside a review of quasi two-level operation and a capacitor voltage balancing method, the paper presents a detailed discussion on space vector modulation implementation and selection of the switching sequence for the five-level inverter case. Additionally, the condition for maximum theoretical modulation index for space vector modulation is established. A prototype five-level diode clamped inverter is used to experimental validated the approach.