Indirect field orientation for induction motors without speed sensor

This article investigates a modified indirect field oriented control strategy that employs a direct estimation of the frequency of the rotor flux vector. The estimate of the frequency of the rotor flux vector is obtained from the directly measurable stator currents and voltages, and is completely independent of the rotor resistance. The proposed scheme can be used in applications where there is no need for speed control or simply to insure the independency of rotor resistance. Experimental results are presented and demonstrate the performance, correctness and feasibility of the proposed methodology.