Three-phase NPC inverter simulation and real-time control

This example deals with the control implementation of a three-level Neutral Point Clamped (NPC) inverter.

With respect to the control of AC-side currents and voltages, NPC converters can be controlled similarly to two-level inverters, as most considerations are topology independent. However, NPCs require particular attention to the balancing of the voltage of the DC midpoint, which is not achieved naturally. Indeed, without proper consideration within the chosen modulation algorithm, or suitable closed-loop control, inevitable system unbalances do not tend to compensate, leading to excessive and potentially dangerous voltage on one of the two DC busses.