Torque Analysis of Electromagnet-Assisted Ferrite Magnet Motors Considering Magnetic Saturation

In this paper, the effects of magnetic saturation and d-q axis cross-coupling on the torque characteristics of an electromagnet-assisted ferrite magnet motor (EMaFM) are investigated through finite element analysis (FEA) and experiments. The EMaFM is a new type of motor, which is a combination of a surface permanent magnet synchronous motor (SPMSM) and a flux-modulating synchronous motor (FMSM). A 1.5-kW prototype machine is used for this investigation, and its inductance and torque characteristics are analyzed on the basis of a mathematical model that includes the mutual inductance between the d-axis and q-axis windings. The results show that the FMSM part is more easily affected by the magnetic saturation and d-q axis cross-coupling compared with the SPMSM part.