Real time flux and torque estimator for induction machines

This paper presents a novel method for flux and torque estimation. Based on the observation and analysis of the behaviour of the classical torque and flux estimator structure in an indirect rotor flux oriented control (IRFOC) of a voltage fed squirrel cage asynchronous machine, the proposed structure is fully independent of the stator resistance. Implemented in dq coordinates, the estimator is based on simple calculus of signal averages. Only stator voltages and currents are required for the estimation, along with maximum and minimum detectors. Flux position and magnitude are estimated separately, and dq fluxes are rebuilt for torque estimation. The estimator is designed for systems running above 0.5 Hz, making it available for induction machine (IM) applications running over a wide range of speed. Simulations are performed on SimPowerSystems.