Comprehensive analysis on carrier-based PWM modulations for advanced composited clamping five-level converter

In order to reduce the total harmonic distortion (THD) of the line-to-line voltage and simplify the circuit structure, an advanced five-level modular multilevel-clamped composited multilevel converter (5L-M-MC²) is proposed [1]. A comprehensive analysis of the level degradation on carrier-based PWM modulation in the 5L-M-MC² system is analyzed in detail in this paper. The line-to-line voltage levels degrade when the modulation index decreases from 1 to 0. The differences of the degradation in the three classic Carriers Disposition PWM modulation methods are pointed out. Their level degradation points are explored to give a better understanding on this advanced 5L-M-MC². Finally, the experimental results of three Carriers Disposition PWM modulations are exhibited to verify the validity of the main contributions in this paper.