Current Control of WRSM Considering Magnetic Saturation Phenomenon

This paper introduces the characteristics of a 120 kW class wound rotor synchronous motor (WRSM) considering the effects of magnetic saturation in electrical steel. The flux linkage due to the rotor windings and the d-axis inductance of WRSM vary non-linearly because of the magnetic saturation. This affects the selection of a current combination for maximum torque per ampere (MTPA) control. The relation between the current combination for MTPA control and magnetic saturation is analyzed in this paper. Finding a current combination that satisfies the requirements is very difficult, because WRSM has complicated current combinations (i
_f
, i
_d
, and i
_q
). Therefore, an algorithm for the calculation of the optimal current is proposed using the Lagrange function, and the current map is presented. Finally, the validation of the selected current combination is performed through the comparison of the results of an experiment and the finite-element analysis.