Precise torque control of induction motor with on-line parameter identification in consideration of core loss

Abstract

This paper describes improved torque control of an induction motor. The control is based on direct field orientation with a rotor flux simulator, and motor parameters in the simulator are estimated by a robust identifier with no sensitivity to the stator resistance. Owing to model mismatch in the controller caused by the equivalent core loss resistance, however, both the field orientation and the parameter identification cannot be carried out perfectly, which results in degradation of torque control performance.In order to improve accuracy of the output torque, the proposed system employs a modified machine model taking the core loss into consideration. Consequently, it has been verified through computer simulations that the technique achieves high precision in torque control within a few percent errors.

Relationship of Parallel Model and Series Model for Permanent Magnet Synchronous Motors Taking Iron Loss Into Account

“…For practical purposes, in order to include a hysteresis loss into , the iron loss resistance is usually treated as a function of the electrical angular velocity [3]. The flux linkage equation for the parallel model is given as (5) where corresponds to a permanent magnet flux linkage [2].…”

“…From a modeling point of view, they can be classified as either parallel or series type. The parallel model inserts an iron loss resistance in the equivalent circuit with the parallel fashion and it is employed in [1]- [5]. By contrast, the series model inserts an equivalent iron loss resistance in the equivalent circuit with the series fashion and it is employed in [6]- [9].…”

Proposition of new mathematical models with stator core loss factor for induction motor

“…Recently, Noguchi and colleagues have attempted the parallel modeling of the core loss, including the core loss of the leakage inductance, and its utilization for vector control [22]. In the practical stage of utilization, however, they have returned, regrettably, to the hypothesis that the core-loss resistance can only be placed in parallel with the mutual inductance.…”

“…Therefore, it is rational to pay attention to the stator magnetic flux interlinking the core rather than the airgap magnetic flux between stator and rotor [19,22,28].…”

Improved adaptive feedback linearization control of induction motors based on online estimation of core loss and rotor resistance

“…On the other hand, precise estimation of rotor resistance is crucial in advanced control of induction motors since it may vary due to the skin effect or temperature variation. There have been a few approaches to online estimation of rotor resistance; however, ignoring core loss effect produces a bias in any rotor resistance estimation algorithm [5][6][7]. And finally it has been well known that for optimum selection of reference flux for efficiency optimization, estimation of core loss is necessary [8,9].…”