Extended Minimum Copper Loss Range Fault-Tolerant Control for Dual Three-Phase PMSM

This paper studies the single open-circuit failure (OCF) in dual three-phase permanent magnet synchronous motors (DT-PMSM) in transport electrification where wide speed range and torque operation range (TOR) are required. A control scheme is developed to extend the TOR with minimum copper loss based on the well-established fault-tolerant control strategy minimum loss (ML) and maximum torque (MT). The ML strategy allows the demanded torque at the reference speed to be delivered with minimum copper loss. The MT strategy presents wider torque capability in post-fault operation without exceeding the current limit, whilst copper loss within the stator winding is not optimized. However, there is a gap in the permissible TOR of these two strategies. A simple switch of strategy, from ML to MT when the limit of ML's TOR is reached, would result in excessive copper loss. The full-torque-operation-range minimum loss (FTOR-ML), inspired by previous work, is developed to mitigate the excessive copper loss, by analytically analysing the corresponding optimsation problems. The FTOR-ML for the DT-PMSM under OCF for different winding configurations, single (1N) and isolated neutral point (2N), combines the merit of ML and MT where the entire TOR of MT is achieved with minimum copper loss. The novel analytical solution of FTOR-ML derived in this paper contributes to highly simplistic implementation for both winding configurations. Experimental result demonstrates the combined merit and effectiveness of the proposed control scheme.