Observer of Rotor Speed in Scalar Control Induction Motor Drive
The paper is devoted to speed-sensorless scalar control system of аn induction motor drive consisting of two loops for control of the rotor speed and the active component of stator current. The rotor speed estimation is based on the linearized dependence of the slip frequency on the active component of the stator current obtained for an IR-compensation scheme. The active current component is calculated as a sum of projections of measured alpha-beta current components onto the voltage vector. The computer model of control system with the proposed rotor speed observer has been implemented to estimate the observer accuracy for different rotor speeds. The control range of the rotor speed has been determined under conditions of the static error being kept less than 1 %.