Sensorless speed control of induction motor using differential algebraic speed estimator

Abstract

There are multiple techniques that have been proposed to estimate the speed of induction motor without the shaft sensor. Since at low speed range most induction motor normally has poor driving performance, there are speed estimation concern at this range. Sensorless speed estimator based on the differential-algebraic approach is implemented in this project. The methodology used is based on advanced modeling capabilities, represented by dynamic modeling of induction motor. It begins with deriving the mathematical model of the induction motor. It also shows that the dynamic equation of induction motor had been transform into suitable model by using Direct-Quadrature (d-q) transformation. Then, the estimator is designed based on differential equations properties. A differential algebraic approach is applied in this project to estimate the speed of induction motor using the measured voltages and current. The second and third order polynomial equation which the coefficient is depend on the stator voltage, stator current and their derivatives is shown to be satisfied. The determined speed is then used in the stabilize dynamic estimator to obtain the smooth estimated speed. With full knowledge of the machine parameters the simulations using MATLAB Simulink is implemented. The estimator demonstrates that the response of induction motor speed is improved especially at a low speed, high precision in speed control, and is more robust to parametric variation and load torque variation.