Modulation selection procedure applied to a high-power adjustable high-speed drive

This paper proposes a systematic procedure to evaluate, compare and select different modulation techniques for a medium voltage variable speed drive. Several indicators are proposed to be analyzed, mainly based on thermal analysis, voltage limitations, dc bus evaluation and load current quality. The suggested procedure is evaluated on a simulation based analysis in a 6.6 kV adjustable speed drive system with a 5-level H-bridge neutral point clamped (HNPC) inverter topology and diode front end (DFE) as rectifier. The use of selective harmonic elimination (SHE) with different number of angles and space vector modulation (SVM) is assessed depending on the load demands (output frequency, modulation index, etc.).