A New PWM Technique for Modular Multi-Level Converters

This digest presents a new pulse width modulation (PWM) technique for a Modular Multilevel Converter
(MMC) topology. The presented converter generates a multilevel output voltage with low harmonic distortion, increased reliability, and design flexibility due to the modular nature of the topology. The topology has several sub-modules that can be inserted or bypassed to synthesize large AC voltages. The proposed PWM technique equalizes sub-module utilization without increasing losses, and retains inherent capacitor voltage balancing. Hardware results are presented in the digest which shows that the proposed modulation scheme results in better performance than conventional schemes such as nearest-level modulation level-shifted carrier PWM, or phase-shifted carrier PWM.