Comparative evaluation of three-level converters using 4.5 kV, 1.2 kA IGBT modules

The aim of this paper is to compare the maximum achievable output current of the Neutral Point Clamped (NPC), Active NPC (ANPC) and Neutral Point Piloted (NPP) Voltage Source Converters (VSC), in a wide range of operating points, by simulating theses converters with 4.5kV, 1.2kA IGBT modules. The maximum currents are limited by the junction temperature of the most stressed semiconductors in a defined operating point, and in order to calculate these temperatures, power losses and thermal models are needed. With their extra NPC switches controlled by a loss balancing system, the ANPC-VSC can handle large currents compared with the NPC in all cases; but for high output voltages and motor operation, the NPP achieves the best performance in terms of the maximum output power.