R. Wieser:
"Some Clarifications on The Impact of AC Machine Iron Properties on Space Phasor Models and Field Oriented Control";
Talk: ICEM, Istanbul, Turkey; 09-01-1998; in: "International Conference on Electrical Machines ICEM'98", (1998), 1.

Recent publications on ac machine controls have proposed various techniques to consider the impact of iron properties in order to minimize losses and to improve torque accuracy. A common way to take iron losses into account is to conceptually place a resistor in parallel to the magnetizing inductance in the equivalent circuit of the machine. However, this modification complicates the differential equations, which are used for the on-line machine model. Moreover, it is an inaccurate approximation of iron losses with respect to variations of fundamental supply frequency and flux magnitude. The proposed method in this paper derives machine state-dependent current phasors, which represent the impact of the iron properties on the flux and torque estimation. These small phasors are added in an appropriate way to the sampled current phasors, which leads to the correct machine representation. This technique does not change or complicate the commonly used model structures. Furthermore, it allows the separate treatment of eddy current and iron hysteresis caused loss components. In general, some clarifications are given on the impact of stator iron properties on machine models with respect to the model structure, as there is a distinct difference between the so-called current- and voltage-model.