An Improved Reduced Parallel Modular Multilevel Converter with Sensorless Capacitor Voltage Balancing

A new improved reduced parallel modular multilevel converter (RP-MMC) and its generalized topology are proposed in this paper. First, a basic four-level dc cell as well as its improved switching pattern to achieve sensorless voltage balancing of the capacitors is proposed. Then, a seven-level inverter is obtained by applying a low-frequency H-bridge to the proposed four-level dc cell. In addition, generalized topology of the proposed reduced multilevel dc cell is presented and described. Moreover, a new sensorless modified nearest level control (MNLC) switching pattern is proposed for the RP-MMC. The presented experimental results verify the feasibility and viability of the proposed seven-level inverter as well as the proposed MNLC modulation technique.