A Novel PWM Scheme and Reduce Switching Frequency Capacitor Voltage Balancing Algorithm for Modular Multilevel Converter

The Modular Multilevel Converter (MMC) is considered the most innovative power converter for high and medium power applications. However, in medium voltage operations, the MMC encounters a significant issue with the output voltage, characterized by Total Harmonic Distortion (THD) and increasing switching frequency due to capacitor balancing. This paper presents a Novel PWM technique that reduces switching frequency capacitor voltage balancing to address the aforementioned problems in the MMC. The proposed PWM technique successfully reduces harmonics to 4.06% while improving the fundamental phase voltage. The updated capacitor balancing approach also decreases the submodule (SM) switching frequency to the number of SMs in the MMC arm (N). The simulations were conducted using MATLAB/SIMULINK, and The outcomes were compared to existing techniques.