An effective carrier based PWM technique for neutral point voltage stabilization of three level inverter

Multilevel inverters have gained lot of prominence in recent times due to their improved output quality at reduced switching stress. At high power levels a two level inverter have high switching stress as the entire supply voltage appears across the switch but in multilevel it is distributed among the switches. The most popular topology among multilevel inverters is DCMLI. But DCMLI suffers from neutral point voltage balancing problem this has raised due to unequal charging and discharging of capacitors. Many CB PWM solutions have been proposed for this problem in all this cases the underlining principle was adding a relevant dc bias to reference signal. In this paper a new technique is proposed. In which dc bias of the carrier is adjusted as per the polarity of capacitor voltage difference and neutral current. The proposed concept is tested using MATLAB simulation software.