LAUSR

An improved superposition method accounting for both permanent magnet (PM) and armature field is proposed to predict the unbalanced magnetic force (UMF) of PM machines having static/dynamic eccentricity. It virtually divides the original eccentric machine into a number of sections along the circumferential direction. Then, a series of concentric machine models are established with equivalent air-gap lengths corresponding to those air-gap sections. From the electromagnetic field of each concentric machine predicted by subdomain method, the air-gap field of the original eccentric machine can be synthesised. Finally, the UMF can be easily obtained by the integral of force density along the air-gap circumference. The effectiveness of the proposed method is validated on both rotating asymmetric and symmetrical PM machines by direct finite-element analysis and experiment, with particular emphasis of rotor eccentricity influence on the UMF of later one.