Comparative Study of Field Modulation Effects in Consequent-Pole PM Machines With Different Stator Slot Configurations

This article presents a comparative study of the magnetic field modulation effects (MFMEs) in consequent-pole permanent magnet (CPPM) machines with different stator slot structures, i.e., open slot (OS), semi-closed slot (SCS) and close slot (CS). The main purpose of this article is to identify and investigate how slot opening affects the MFME and the torque performance. The torque proportions of main air-gap working harmonics in the CPPM machines with different stator slot configurations are quantitatively evaluated by the finite element (FE) method, which reveals that the stator slot configurations have a great influence on MFME. Besides, the influence of the stator slot-opening ratio on MFME is quantified, which demonstrates that the torque proportion of MFME decreases with the slot-opening ratio due to its reduced field-modulated harmonics. Finally, a 12-slot/14-pole CPPM prototype with an SCS configuration is manufactured and tested to validate the simulated analysis.