Implicit position and speed estimation algorithm without the flux computation for the rotor side control of doubly fed induction motor drive

摘要

A simple and implicit sensorless algorithm for estimating the rotor position and speed of the doubly fed induction machine is proposed in this study. Instead of computing the stator magnetic flux directly or indirectly, the stator flux vector components in the stationary reference frame are substituted with analytical equivalents in terms of measurable stator and rotor quantities. Thus, it is an implicit estimation process devoid of computing any flux terms and requires only the measured stator voltage and currents in stator and rotor windings apart from knowledge of the machine parameters. It is an open-loop scheme. However, it does not involve integration, recursive techniques, re-computations or programmable low-pass filters etc. Starting on the fly, accurate estimation near synchronous speed, immunity against variation in stator and rotor resistances or in the magnetising inductance are the principal advantages of the algorithm. Reduced complexity and the computational burden facilitate the easy implementation of the algorithm on a low-cost fixed point processor. Excellent agreement between the simulation and test results on a laboratory doubly fed induction motor validates the proposed estimation algorithm implemented for the vector control of a doubly fed induction motor. On the whole, the estimation algorithm is a new insight that holds promise in the area of sensorless control of the DFIM, whether used as a motor or as a generator.