Dynamic Modeling of Surface-Mounted Permanent Magnet Motors Considering Saturation

This paper developed a dynamic hybrid field model (DHFM) for surface-mounted permanent magnet (SPM) motors coupled with external drive circuit considering motor saturation. In the proposed model, the iron saturation of SPM motor is equivalently replaced by the saturation current in the slot opening and therefore the analytical solution of the air-gap field is determined. Based on the air-gap field, the total flux linkage and electromagnetic torque is calculated. The instantaneous inductance is also derived from DHFM using frozen permeability method. The instantaneous back-EMF is determined by the flux linkage produced by PM separating from the total flux linkage. Hence, according to the circuit model and mechanical model, the winding current at next step can be obtained. The proposed model is more efficient in terms of computation and its accuracy is validated by FEM results.