Comparative Study of the Torque Ripple and Iron Losses of a Permanent Magnet Synchronous Generator Driven by Multilevel Converters

This paper studies and analyzes the performance of permanent magnet synchronous generator (PMSG) drives with multilevel power converters used in medium voltage renewable power generation systems. The cases of electrical machine drives with 2-level back-to-back-connected voltage source converters as well as 3-and 5-level neutral-point-clamped converters are examined. The converters have been constructed with silicon-carbide (SiC) power switches. The comparison in the power converters efficiency and power quality is conducted by using simulation results obtained by the Matlab/Simulink and PLECS programs for several operating conditions. For the needs of the comparison, a medium voltage PMSG is designed and its efficiency and torque ripple are calculated by using the finite element software ANSYS Maxwell. Several simulation results are presented and discussed throughout the paper in order to demonstrate the improvements in the PMSG torque ripple and the iron loss reduction that can be achieved by using multilevel converters