Neutral-point voltage balancing in three-phase NPC converters using multicarrier PWM control

Multilevel converters are powerful converters in the medium/high power range. Inside this family of converters, the three-level neutral point clamped converter has its own importance. The main control methods associated with this converter are the carrier-based PWM with added homopolar components and the space vector PWM. One of the most important features of the NPC converter is the neutral point voltage balance. This paper analyses the voltage balancing issue and shows that a simple control loop maintains the voltage balance in different operating conditions.