Investigation of Double-Side Field Modulation Mechanism in Consequent-Pole PM Machines With Concentrated Windings

Abstract

In this article, the field modulation effect (FME) of consequent-pole permanent magnet (CPM) machine is revealed and investigated from the perspective of a double-side slotting effect (DSSE), which can characterize and elaborate its torque production mechanism. Since the CPM machine features that both PM and armature fields are modulated by stator /rotor teeth, which generates more field harmonics contributing to the torque production compared with conventional surface-mounted PM (SPM) machine. A simplified PM magneto-motive force (MMF)-permeance based model is first established to confirm the effective working harmonics of the CPM machine. The contributions of dominant air-gap field harmonics to the torque production are then demonstrated and quantified based on Maxwell stress tensor (MST) method. The impacts of FME on the torque performance of the CPM machines with different stator-slot/rotor pole combinations are subsequently investigated by the finite element (FE) method and compared with those of conventional SPM counterparts. Besides, the influences of rotor PM parameters on the FME of the CPM machine are also evaluated. Finally, the experimental measurements on a 12-slot/14-pole CPM machine prototype are carried out to validate the theoretical and FE analyses.