Full Torque Operation Range Fault-Tolerant Control with Minimum Copper Loss for Dual Three-Phase PMSM

This paper studies the single open-circuit failure (OCF) in dual three-phase permanent magnet synchronous motor (DT-PMSM) at high load and motor speed for application in transportation that requires wide speed range and torque operation range (TOR). A new control scheme is proposed to achieve minimum loss in full speed range based on the well-established fault-tolerant control strategy minimum loss (ML) and maximum torque (MT). The minimum loss (ML) strategy allows demanded torque at reference speed to be delivered with minimum copper loss. The maximum torque (MT) strategy presents wider torque capability in postfault operation without exceeding current limit, while copper loss within the stator winding is not optimized. However, there is a gap in the permissible TOR of these two strategies. Simple switch of strategies, from ML to MT when the limit of ML's TOR is reached, would result in excessive copper loss, which can potentially be eliminated. The proposed full-torque-operation-range minimum loss (FTOR-ML) in this paper will mitigate the excessive copper loss. The novel FTOR-ML for the DT-PMSM under OCF with both single (1N) and isolated neutral point (2N) has combined the merit of ML and MT where the entire TOR of MT is conserved with minimum copper loss. The analytical solution of FTOR-ML is derived in this paper. The simulation results validate the superiority of the proposed control scheme.