A Novel Method for Vector Control of Three-Phase Induction Motor under Open-Phase Fault

Abstract

Abstract. The majority of electrical machines such as induction motors can be modeled by an equivalent two-phase machine model (d-q model). A three-phase induction motor with one of the stator phases opened (faulty three-phase induction motor) can be also modeled by an equivalent two-phase machine. If a conventional vector control method for balanced three-phase induction motors is used for this faulty machine, significant oscillations in speed and torque will result. In this paper, a novel technique for vector control of faulty three-phase induction motors based on rotor-field oriented control (RFOC) is presented. The performance of the proposed method was evaluated using MATLAB software. The results show that it achieves significant improvements in the oscillation reduction of the speed and torque responses. Keywords: field-oriented control; open-phase fault; speed and torque oscillations; three-phase induction motors; vector control. 1 B IntroductionNowadays, field-oriented control (FOC) of induction motors (IMs) is broadly adopted to obtain high dynamic performance in drive systems. Applying a conventional control strategy such as FOC to a faulty three-phase IM (threephase machine under open-phase fault) will result insignificant oscillations in the speed and torque output [1][2][3][4]. It was shown in [1-4] that using transformation matrices, the FOC equation structure for a faulty three-phase IM can be transformed into a structure that is similar to that for a balanced IM. However, the backward terms of the stator voltage equations were neglected in the process of calculating the FOC equations [2,3]. The proposed method in [4] for vector control of faulty IMs is also extremely dependent on the regulation of the current proportional-integral controller. Reference [5] reviews and compares fault tolerant AC drives on the basis of features, costs and limitations.It is also interesting to note that the three-phase IM model with one phase cutoff is, in principle, similar to the model of a single-phase IM with two windings.

A Novel Method for IRFOC of Three-Phase Induction Motor under Open-Phase Fault

“…From (17) and (18), it can be seen that the rotor voltage and the torque equations are similar to the healthy three-phase IM equations. Consequently, it is possible to control faulty machine by the some modifications in the conventional RFO vector control.…”