Dodecagonal Space Vector PWM for Cascaded H-Bridge based STATCOM

This paper proposes a new circuit topology for Cascaded H-bridge based static compensator (STATCOM). The proposed circuit consists of H-bridge cells with asymmetric capacitor voltages. However, the difference in voltage among the H-bridge cells is less than 10% leading to a modular design. The space vector diagram formed by proposed circuit consists of six twelve sided polygons (dodecagons). Dodecagonal Space Vector diagram offers increased modulation range as compared to conventional hexagonal space vector diagram. The increased voltage obtained can be used suitable in static compensators as shown in this paper. Additionally decagonal space vector pulse width modulation on this dodecagonal space vector diagram offers several advantages like reduction in harmonics, reduction in dv/dt rating of switches, complete elimination of 6n +/- 1 harmonics (for n= odd) etc. Simulation results demonstrating the benefits of Dodecagonal Space Vector PWM in STATCOM application are also presented.