Diagnosis of Stator High Resistance Connection Based on Multiple Reference Frame Controllers in Asymmetrical Six-Phase AC PMSM Drives

Increasing interest has been shown in multiphase drives for medium and high-power industrial applications, owing to their specific advantages when compared to their three-phase counterparts. High-resistance connections cause stator resistance unbalance, leading to a degraded performance of the machine, which in turn affects the efficiency and reliability of the machine and the overall system. In this paper, an improved field-oriented control scheme is designed to detect stator high-resistance connections, localize the affected phase/phase, and compensate the effect of the stator fault in order to keep the drive behavior nearly unchanged until a safe procedure to stop the drive is activated. The proposed control strategy is based on an analytical model that takes into account the stator resistance unbalance introduced by a high resistance connection, exploiting the control signals derived from multi-reference frame current regulators. The theoretical analysis of the diagnosis approach and the corresponding fault-tolerant control strategy are fully tested by numerical simulations.