Detection of magnet demagnetization and high-resistance connections in five-phase surface-mounted permanent magnet generators

The interest in multiphase machines is increasing, owing to their advantages with respect to the three-phase ones, in particular for medium and high power applications. In this paper, the model of a five-phase surface-mounted permanent magnet synchronous generator, under mixed demagnetization of the rotor magnet trailing edges, and unbalance of the stator phases due to High-Resistance (H-R) connections, is developed. Then, a control scheme that can diagnose the rotor magnet demagnetization and the stator resistance dissymmetry, and ensure a nearly undisturbed behavior of the system, is presented. A current control scheme, which is based on multi-reference frame current regulators, is proposed. The on-line monitoring technique exploits the degrees of freedom of a multiphase generator. The effectiveness of the presented control scheme is verified by numerical simulations.