Consequent Pole Permanent Magnet Machine With Modular Stator

Owing to a group of permanent magnets (PMs) with the same magnetization direction are replaced by salient iron core, the consequent-pole (CP) PM machines generally suffer from asymmetry flux density. This will leads to the even-order back-EMF harmonics, which have negative influence on the electromagnetic performance. It is widely known that the even-order back-EMF harmonics cannot be eliminated for the machines with odd backEMF phasor belongs to one phase in one machine periodicity, i.e., N
₀
is odd (N
₀
= NS/mt, where NS is the number of slot for one machine, t is the unit sub-machine periodicity, m is the number of phase). Hence, this paper proposes a general modularization method solving this problem. The elimination principle of even-order back-EMF harmonics in the modular stator (MS) is explained by the star of slots. Further, the MS with auxiliary winding (AW) and auxiliary teeth (AT) are proposed to improve the electromagnetic performance of the MS CP (MSCP) PM machine. Then, the electromagnetic characteristics, including open circuit field distribution and back-EMFs, torque characteristics, unbalanced magnetic force (UMF), loss distribution characteristics as well as efficiency contours are comprehensively compared. Finally, the MSCP PM machine with auxiliary winding (MSCP-AW) is fabricated and tested to verify the theoretical analysis as well as the finite element (FE) results.