Design Optimization and Performance Investigation of Linear Doubly Salient Slot Permanent Magnet Machines

Novel linear doubly salient slot permanent magnet machines (LDSSPMMs) are investigated in this paper. First, the machine topology and operation principle are introduced, and the choices of feasible slot/pole combinations and winding configurations for three armature phases are discussed. Then, the 12 slots and 10/11/13/14 poles LDSSPMMs with double-layer (DL)/singlelayer windings are globally optimized using genetic algorithm. The electromagnetic performances including flux linkage, back electromotive force (back EMF), detent force, and static force-current characteristics are comparatively studied using two-dimensional (2-D) finite-element analysis (FEA). It shows that 12 slots/13 poles (12s/13p) and DL winding are the optimal choices to provide higher thrust force as well as lower force ripple. Moreover, the risk of local irreversible demagnetization of PMs is analyzed, which only occurs at very limited corners of the PMs and can be eliminated by PM shaping. Furthermore, the electromagnetic performances between linear variable flux reluctance machines (LVFRMs), linear hybrid-excited slot PM machines, linear primary yoke PM machines, and LDSSPMMs are comparatively studied. It shows that LDSSPMM can provide much higher thrust force than LVFRM at the same copper loss. With the increase of copper loss, LDSSPMM exhibits better thrust force capability than other machines. Finally, a prototype of 12s/13p DL-LDSSPMM is manufactured and tested to validate the 2-D FEA predicted results.