Diagnostic Method of Rotor Cracks and Local Demagnetization by Using the Measuring Coils for the Permanent Magnet Synchronous Machines

Abstract

This paper proves that the use of conventional diagnostic methods of rotor crack and local demagnetization based on the harmonic analysis of the output voltage or counter-electromotive force is effective only with a certain ratio of the number of slots and poles. This statement was proved experimentally. The diagnostic method of the rotor cracks and local demagnetization which is universal for all types of windings and the number of slots of 2-pole synchronous electric machines with permanent magnets is proposed. The mathematical apparatus for the implementation of the proposed method is developed and verified with the help of FEM and experimental studies. All the experimental studies have been carried out for various rotor magnetic systems and a different number of stator slots.

A Fault-Tolerant Control Strategy for D-PMSG Wind Power Generation System

“…After a long-term operation in relatively harsh operating environments such as desert, gobi, and sea surface, the PM in D-PMSG may have demagnetization faults due to high temperature, chemical corrosion, mechanical vibration, and other factors [5,6]. When a large-scale generator set connected to the grid has demagnetization faults, the terminal voltage of the generator will decrease, and the generator will absorb a large amount of reactive power from the system [7], which will cause fluctuations in the electrical parameters of the power grid and affect the operation safety of the power system.…”