Bild: Kathrin Velte


Electrical Engineering and Information Technology


Electrical Energy Conversion

Working area(s)

Electrical Machines


Smart Grids

Title of dissertation

Calculation of redundantly fed permanent magnet synchronous machines for wind turbines

Summary of dissertation

Multi-megawatt inverter-fed permanent magnet synchronous machines (PMSM) are used for gearless, high torque, speed variable drives such as wind turbine generators. Due to the limited output power of an individual DC link inverter, multiple three-phase inverters are used to feed a single three-phase machine. Typically a connection pattern in the way of individual sector machines is chosen. In this case each inverter feeds a certain sector of the stator winding or a group of sectors of the stator winding leading to a symmetrical feeding pattern. In normal operation all inverters will feed the same current to their group of sectors and thereby acting as parallel branches of one winding. In this case the geometric pattern of the feeding is irrelevant. But the symmetry of the feeding will be violated, if one inverter is disconnected from its winding sector and operation is continued with certain sectorial winding groups idling. This scenario, called ”redundancy operation”, is of major interest if the machine is supposed to continue operation after an inverter or winding fault by using its inherent redundancy due to the separated sectorial machines with individual feeding. But unbalanced magnetic pull, additional eddy current losses in the solid rotor yoke and torque pulsations will occur in this operating mode. Fundamental to the understanding and calculation of these effects is the calculation of the wave harmonics of the stator winding in redundancy operation.


B.Sc. and M.Sc. Electrical Engineering, TU Berlin


N. Erd, A. Binder, “Eddy Currents in Solid Rotor under Spatially Intermittent Feeding of the Stator Winding”, ICEM, Alexandroupoli, Greece, 2018 (to be published)

N.Erd, A. Binder, “Numerical and Analytical Analysis of Wave Harmonics under Spatially Intermittent Feeding”, ICEM, Alexandroupoli, Greece, 2018 (to be published)

X. Li, N. Erd, J. An, G. Messager, A. Binder, “Design of a High-Speed Flywheel Energy Storage Demonstrator”, VDE Antriebssysteme, Karlsruhe, Germany, 2017

N. Erd, X. Li, A. Binder, “Power Flow Simulation of Flywheel Energy Storage Systems for Tramways”, ICREPQ, Malaga, Spain, 2017

X. Li, N. Erd, A. Binder, “Evaluation of Flywheel Energy Storage Systems for Residential Photovoltaic Installations”, SPEEDAM, Anacapri, Italy, 2016

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