Simplified Space Vector Pulse Width Modulation for Four-Level Neutral Point Clamped Inverter

Multilevel inverters have become a suitable candidate for high power applications due to their output performance and power density. In particular, Four-level neutral-point-clamped inverter (NPC) has received a lot of attention due to the demands of commercial and industrial applications requiring higher DC link voltages and ever-improved power quality compared to three-level inverter. One of the primary challenges for multilevel inverters is that the space vector diagram for modulation schemes becomes complex as the number of voltage levels increases. This paper presents a Simplified space vector pulse width modulation (SSVPWM) for four-level neutral point clamped inverter to overcome this issue. This method reduces the quantity of sub-regions for a four-level inverter space vector diagram, compared to the conventional space vector PWM method. Furthermore, the space vector diagram of the four-level converter is transformed into a two-level space vector diagram, which reduces complexity and computation burden. Performance of the SSVPWM method is verified through the simulation results.