A Current Online Prediction Based Dead Time Compensation Method for MMC Low Common Mode Voltage CPS SPWM

The modular multi-level converter (MMC) exhibits significant potential in voltage source converter-based high voltage direct current (VSC-HVDC) transmission and high voltage motor drive. Low common mode voltage (CMV) modulations for MMC can effectively reduce the common-mode (CM) electromagnetic interference (EMI) in MMC by minimizing the CMV fluctuations. However, the dead time is necessary for protecting the power semiconductor devices in bridge circuits like MMC, which make the low CMV modulations fail and cause serious CM EMI. In this paper, a current online prediction based dead time compensation method (COP-DTCM) for MMC low CMV carrier phase shifted (CPS) sinusoidal pulse width modulation (SPWM) is proposed for the first time, to eliminate the CMV fluctuations in MMC. Besides, the mechanism and characteristics of the CMV fluctuations in MMC caused by the dead time are analyzed in detail. The compensation strategy of the carrier phase positions and modulation signals for MMC under CPS SPWM is presented based on the prediction results of arm currents. Finally, the effectiveness and correctness of the proposed COP-DTCM are verified by the simulation and experimental results. Therefore, this paper provides an effective CM EMI suppression method for MMC with low EMI requirement.