Design Considerations for the Intermediate Circuit of a Multimegawatt Medium-Voltage Neutral-Point-Clamped Inverter

In this paper, the layout of the intermediate circuit of a medium-voltage neutral-point-clamped inverter is analysed. In the analysis, the placement, orientation and to some extent the number of the DC link capacitors is considered. Commutation loop inductances of seven alternative laminated DC link busbar designs are compared against each other. The comparison is carried out by finite element analyses using the Ansys Q3D Extractor and Simplorer circuit simulator. Finally, a prototype of the phase-leg is is built an measured and a good agreement between the simulated and measured results is observed.