| Abstract |
The power ratings of wind energy conversion systems (WECS) are increasing considerably due tohigh demand on wind power. Thus, multilevel power converters are becoming an interesting solutionin the largest WECS, especially the three-level neutral-point-clamped (3L-NPC) thanks to its simpleimplementation and proper performance compared to other topologies. However, the main drawbackof the 3L-NPC is that the power losses are unevenly distributed among the switching devices, limitingits output power capability. Current literature focuses on the three-level active neutral-point-clamped(3L-ANPC) as an evolution of the 3L-NPC, enabling a more even power loss distribution. However, inthe 3L-ANPC there are still some devices suffering from both large switching and conduction powerlosses. Thus, this paper proposes new design guidelines for a 3L-ANPC inverter to force that eachdevice mainly withstands either switching or conduction power losses. Then, the most suitable deviceis selected for each position, enabling a significant improvement in power loss distribution, thermalperformance, converter efficiency and output power capability. A 2 MW low-voltage WECS issimulated with an electro-thermal model developed in PLECS, reaching a reduction of around 25\% inpower losses, a reduction of 50\% in maximum junction temperature increase above ambienttemperature, a reduction of 75\% in maximum junction temperature variation, and an increase ofaround 85\% in converter output power rating, compared to the conventional 3L-NPC and the 3L-ANPC. |
