Comparison of partitioned stator switched flux permanent magnet machines having single- and double-layer windings

In this paper, the electromagnetic performance of partitioned stator switched flux permanent magnet (PM) (PS-SFPM) machines with single- and double-layer windings are compared when the inner stator is equipped with the same number or half the number of PMs as that of the outer stator teeth. Electromagnetic performance of these PS-SFPM machines is investigated by 2-dimensional finite element analysis (FEA), based on the globally optimized designs for the maximum average electromagnetic torque. FEA results show that for 12-outer-stator-tooth and 12-inner-stator-PM PS-SFPM machines the double-layer windings produce higher torque than the single-layer windings, but for 12-outer-statortooth and 6-inner-stator-PM PS-SFPM machines it is opposite, i.e. the double-layer windings produce less torque than the single-layer windings. Overall, the 12-outer-stator-tooth and 12-inner-stator-PM PS-SFPM machines produce higher torque and less torque ripple than the 12-outer stator-tooth and 6-inner stator-PM PS-SFPM machines.