Common-Mode Voltage Reduction with the Optimal PWM Signal Modulation Technique

The rapid development of electric vehicles, electric vehicle charging stations, renewable energy harvesting and storage systems, and various other energy conversion systems has increased the focus on multilevel inverters. These inverters are highly effective in reducing harmonic distortion. However, Common-Mode Voltage (CMV) remains a significant challenge, causing negative impacts, such as reduced component lifespan, decreased control system reliability, and substantial electromagnetic interference. This study introduces a straightforward and highly practical technique that ensures effective CMV reduction. The technique enhances the traditional SPWM method by offsetting the control signal to optimize switching frequency and produce better PWM signals. This method, referred to as Optimal PWM Signal Modulation (OSM), has shown superior CMV reduction capabilities for multilevel inverters compared to the phase disposition technique. The effectiveness of the OSM technique has been evaluated through simulations and practical experiments on a three-level H-bridge converter and the LAUNCHXL-F28379D development kit from Texas Instruments.