Fast Capacitor Balancing Scheme for Low Voltage Cascaded H-bridges in Multilevel Dodecagonal Space Vector Structure

Multilevel dodecagonal space vector structure generation using switched capacitive filter with single DC link requires large filter capacitors. This paper proposes an algorithm with modified topology to reduce the large capacitance requirement. Modular units of equal low voltage cascaded H - Bridges are used to create redundancies which helps in avoiding large duration of charge or discharge of capacitor, causing voltage ripple. To utilize these created redundancies, proper selection of redundant states by considering capacitor voltage status and corresponding phase current at multiple instances within a sampling interval are made and capacitor voltages are balanced within required band with reduced value of capacitance. Results for the proposed drive scheme is included in this paper which validates the effectiveness of the algorithm.