Magnetic Equivalent Circuit Modelling for Flux Modulation Axial Flux Permanent Magnet Machine With YASA Topology

ABSTRACT By combining the advantage of yokeless and segmented armature (YASA) machine and flux modulation effect, the flux modulation YASA (FM‐YASA) machine exhibits superior torque density and efficiency. The finite element (FE) method is the most accurate way to predict the machine performances. However, it will cause a heavy computational burden. Therefore, a magnetic equivalent circuit model (MECM) is proposed in this paper to analyse the FM‐YASA machine rapidly, which is 498 times faster than three‐dimensional FE analysis and 3.4 times faster than two‐dimensional FE analysis approximately. Compared with traditional lumped‐parameter MECM, the tiny rectangular grids are adopted for the refined modelling of airgap, permanent magnet (PM), modulation slot and stator slot opening. The refined magnetic grids of airgap and PM unify the model to achieve a dynamic MECM which can auto‐update connection of the magnetic reluctance during rotor rotation. Since PM with stepped slots is designed to facilitate assembly and enhance mechanical strength, the leakage flux of PMs is captured accurately by the refined PM model. The effectiveness of the proposed MECM is verified by the FE analysis and experiment, with errors < 5%.