Speed Estimation of Vector Controlled Three-Phase Induction Motor Under Four-Quadrant Operation Using Stator Currents and Voltages

This paper presents a sensorless speed estimation method for three-phase induction motors. The induction motor is field oriented controlled. The method uses the Γ-equivalet circuit of the induction motor. The differential equations of the induction motor are simplified and therefore obtained two different set of equations to calculate the rotor speed. These two different equations are used together because when the denominators of these sinusoidal equations become zero than it causes division by zero in calculations. The proposed method estimates the rotor speed of the field oriented controlled induction motor accurately. The method is verified with simulations in MATLAB/Simulink in wide operating speed ranges under four quadrant operation of the field oriented controlled induction motor.