SPEED OBSERVER FOR SENSORLESS ENERGY GENERATION SYSTEMS BASED ON FIELD ORIENTED INDUCTION GENERATOR

The paper presents a novel adaptive speed–rotor fluxlinkage observer for sensorless field oriented control of induction generators. The proposed solutionis based on Matsuse observerstructure to-gether with specially designed correction termsand utilize current measurement and calculated stator volt-ages for real-time flux and speed reconstruction. A special coordinate transformation is used to avoid non-linear parametrization in the right side of flux linkages differential equations. Adaptive observeris designed in two steps: at the first step nonadaptive flux linkage observer is designed under condition of speed meas-urement; at the second step adaptive to rotor speed version of the flux linkage observer is designed. Infor-mation about rotor speed for adaptive flux observer is calculated by developed speed observer. AsecondLyapunov's method together with adaptive control theory are utilized for observer's correction terms synthe-sisand stability proof. Designed adaptive observer under persistence of excitation conditions guaranteeslocal exponential estimation of constant rotor speed and flux linkage vector components of induction ma-chine.From the practical point of view persistency excitation conditions are met if rotor flux linkages are nonzero. Proposed solution investigated by simulations. It is shown, that developedadaptive speed observer provides asymptotic estimation of induction motor currents, speed and fluxlinkagecomponentsunder con-stant speed conditions. For varying speed proposed observer provides estimation of required variableswith a small dynamic error.Proposed observer can be used in energy generation systemsbased on induction generators as well as in sensorless induction motor-baseddrive systems with constant or slowly varying ro-tor speed.