PROJECT TITLE :

An Improved Capacitor Voltage-Balancing Method for Five-Level Diode-Clamped Converters With High Modulation Index and High Power Factor

ABSTRACT:

The capacitor voltage imbalance may be a important issue of five-level diode-clamped converters (5L-DCC). To handle this issue, an inner-hexagon-vector-decomposition-based space-vector modulation (VDSVM-H1) approach is provided in the literature, which obtains the capacitor voltage balancing with high modulation index and high power issue, but renders some drawbacks. To overcome these shortcomings, a completely unique capacitor voltage balancing methodology is proposed here. 1st, the previous VDSVM-H1 approach is modified by introducing six new vector sequences to every triangle and applying a replacement vector selection rule such that the converter can not violate the 5L-DCC switching mechanism in all operating conditions. Second, the variation of the road-to-line voltage output in one sampling amount is restricted to at least one- or two-level in the optimized region, rather than the three-level in the previous VDSVM-H1 approach, that suggests that less harmonics generating in the ac-side outputs. Finally, the simulation and experimental results show that the proposed technique will improve the VDSVM-H1 with convincing results.