Design and Performance Analysis of a Novel Modular Multilevel Converter Cell for Enhanced Voltage Levels and Power Quality in Medium-Voltage Motor Drives

This paper presents a novel modular multilevel converter (MMC) cell, designed with four capacitors and 12 switches, capable of generating 9 voltage levels with equal capacitor voltages and up to 21 voltage levels with alternative capacitor configurations. The proposed cell demonstrates unique features, including voltage level production independent of current direction and a capability to block the DC link current path after short circuit occurrence, regardless of current direction. This flexibility and robust current blocking capability enhance system reliability and safety under fault conditions. Through simulation on an MMC drive with an induction motor load, the proposed cell is shown to achieve significant improvements in efficiency and voltage modulation quality, which directly contribute to reduced harmonic distortion and increased drive efficiency. These characteristics make the proposed cell a promising candidate for applications in medium-voltage motor drives, where reliability and performance optimization are crucial.