Selecting IGBT module for a high voltage 5 MW wind turbine PMSG-equipped generating system

In this paper, a fairly high voltage generating system for a 5 MW generating system is investigated. The generating system consists of a surface mounted PMSG (Permanent Magnet Synchronous Generator) with a 2-level transistor converter. The focus is on utilizing three available high voltage IGBT-modules, and to investigate the resulting losses when using them to compose a converter, in order to observe the difference as well as the best choice. In addition, the ideal dc-link voltage for a certain module as well as for a certain main average wind speed is studied. It is found that the most suitable module to use from the loss point of view is the 1.7 kV module, the one with the lowest voltage rating. The difference towards using the 6.5 kV module is a loss increase in the converter at rated operation of 62 %. This is in spite of that a converter composed of the 6.5 kV module has less than half of the conduction losses compare to 1.7 kV module. Accordingly, it can be understood that the switching losses increase much stronger than the conduction losses decrease when using a module with higher voltage rating. When looking at the average annual energy efficiency difference, the best annual efficiency is also achieved when the converter is composed with the 1.7 kV modules.