TY - Journal Article AU - Konstantinou, G. AU - Pou, J. AU - Ceballos, Salvador AU - Darus, R. AU - Agelidis, V.G. TI - Switching Frequency Analysis of Staircase-Modulated Modular Multilevel Converters and Equivalent PWM Techniques PY - 2016 PB - IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA AB - The large number of voltage levels in a modular multilevel converter (MMC) make staircase modulation a feasible alternative, particularly in high-power applications. However, staircase waveforms do not necessarily mean operation of the MMC submodules (SMs) at the fundamental frequency. This paper presents an analysis of SM switching frequencies in staircase-modulated MMCs and their correlation to the modulation index and load phase angle. A carrier-based pulsewidth-modulation (CB-PWM) equivalent technique is also developed. This analysis demonstrates that CB-PWM techniques provide a similar switching frequency with superior harmonic performance and improved voltage balancing characteristics at all modulation indices compared to staircase modulation. The theoretical analysis is verified with extensive simulation results for MMCs with different SMs and experimental results from a laboratory prototype. SN - 0885-8977 UR - http://hdl.handle.net/11556/267 DX - 10.1109/TPWRD.2015.2416759 ER -