Flux-weakening control performance of partitioned stator switched flux PM machines

This paper firstly investigates the flux-weakening control performance of two types of new partitioned stator switched flux permanent magnet (PM) (PS-SFPM) machines and then proposes a novel mechanical flux-weakening technique. The PS-SFPM machine topologies, operation principles and flux weakening control methods are described. In addition, it is shown that by mechanically varying the relative position of two stators of the PS-SFPM machine, the PM flux-linkage can also be varied and hence it can provide improvement of the speed range and torque capability. The optimal relative mechanical angle is derived to enable the maximum torque capability and reduce or even avoid the flux-weakening current injected by the inverter. The proposed technique is verified by 2-dimensional (2D) finite element (FE) analyses and experiments on the prototype machines.