Modeling of slotless surface-mounted PM synchronous motor for sensorless applications

Accurate modeling of PMSM needs considering the special geometry and nonlinear magnetic characteristics of machine parts. In this paper an analysis of a slotless surface mounted permanent magnet synchronous motor is presented including mathematical modeling and measurement results. To extend the electrical model with the rotor position dependent effect of saturation, the stator flux-current function was expanded to a second order Taylor polynomial form and the position dependency of coefficients was determined based on measurement and simulation results. The paper includes the mathematical techniques to expand the vector valued and multivariable flux-current function and transform the nonlinear second order part between stator and rotor oriented forms.