Fault Impact on Dual-Rotor Surface Permanent Magnet Synchronous Generator via the Finite Element Method

Permanent magnet synchronous machines produce high torque density, making them suitable for lightweight applications, such as electric vehicles, or for low-speed applications, such as offshore wind turbines and tidal energy systems. In offshore renewable applications, the high torque density of permanent magnet machines enables direct coupling between the generator shaft and the turbine blade shaft, eliminating the gearbox. Moreover, permanent magnet synchronous machines are brushless, offering, therefore, another advantage by reducing maintenance requirements in offshore generation systems. It is evident that these machines must be designed with the least required maintenance. When a fault occurs in the machine, power losses typically increase, generating excess heat that can further damage the system. Therefore, diagnosing the fault is of great interest to develop a plan to address it. The most common faults in permanent magnet synchronous generators include inter-turn short circuits (ITSCs), partial and uniform demagnetization, and eccentricity faults, which can be classified as static, dynamic, or mixed. This study investigates the impact of these faults on a dual-rotor permanent magnet synchronous generator (PMSG) known as C-GEN. The main variables that will be discussed are the generator's voltage, current, power input and output, efficiency and magnetic field. The results showcase the necessity for innovative diagnostic strategies to detect the faults in early stages.