Analysis of Airgap Field Modulation Principle of Flux Guides

This paper is extended to characterize the performances of machines featuring flux guides based on the general airgap field modulation theory (GAFMT). The magnetomotive force (MMF) modulation operator of variable flux guides is proposed to describe the detailed modulation behavior on the primitive magnetizing MMF distribution, and two popular flux guides topologies, namely synchronous reluctance machine (SynRM) and brushless doubly fed reluctance machine (BDFRM) are described from the perspective of airgap field modulation mechanism. Three kinds of harmonic components namely \pmbpf,(\pmblN\pmbMB+\pmbpf) and (\pmblN\pmbMB-\pmbpf) influenced by corresponding magnetic field conversion factors contribute to the effective flux density and torque production. In addition, electromagnetic performances such as airgap flux density, torque density, cogging torque and inductance characteristics are correlated with their initial key topological parameters by certain analytical expressions and compared fairly between the SynRM and BDFRM. The agreement among the theoretical analysis and the 2-D finite element analysis (FEA) verifies the effectiveness of the proposed analysis.