Nine Level Modular Multilevel Converter with Modified Level Shift Modulation Technique for Reduced Switching Frequency

This study introduces a new approach to Pulse Width Modulation (PWM) known as the adapted DC level shift PWM technique (DC-PWM), which is applied to a nine level modular multilevel converter. This modulation technique involves interleaving the modulated waveform with a Direct Current (DC) level, while ensuring that quarter wave symmetry is preserved. By implementing an adjusted level shift ۱/۴ DC-phase disposition (PD) PWM and ۲/۴ DC PDPWM modulation technique, the switching frequency of the Nine level Modular Multilevel Converter (MMC) has been successfully reduced. The technique's effectiveness has been confirmed through validation using Simulink/MATLAB and an experimental setup. The simulation results show a notable decrease in the frequency of action switching. When it comes to harmonic performance for phase voltage, line voltage, and capacitor voltage, the Type-۳ ۱/۴ DC-PDPWM technique generally outperforms the ۲/۴ DC-PDPWM technique. The ۲/۴ DC-PDPWM Type-۲ demonstrates impressive performance, particularly in terms of phase current and capacitor voltage %THD. The selection of these techniques will be determined by the specific performance needs and the trade-offs in complexity and harmonic suppression that are deemed acceptable for the intended use.

کلیدواژه ها:

Capacitor voltage balancing ، Modified Level shift pulse width modulation ، Modular Multilevel Converter ، Regular level shift modulation