Robust Control Algorithms in Vector Oriented Control of Induction Motor Tomáš Duda, Antonín Víteček Department of Control Systems and Instrumentation VŠB - Technical University of Ostrava Ostrava, Czech Republic Email: tomas.duda@highlite.cz , Antonin.vitecek@vsb.cz Abstract — The paper describes the design of robust control algorithms for the vector oriented control of an induction motor using the state variable aggregation method. The control algorithms were designed for the MIMO non-linear mathematical model of an induction motor in an orthogonal coordinate system synchronously rotating with a reference frame. The designed control algorithms were verified by computer simulation in the program MATLAB – Simulink. Keywords - robust control algorithms; induction motor; state variable aggregation method; nonlinear control systems synthesis; I. INTRODUCTION The paper deals with a design of robust control algorithms, which operates in sliding modes using a non-linear control synthesis called the state variable aggregation method. This method allows the design of the non-robust control (knowledge of the mathematical model of controlled subsystem and disturbances is required), the robust control with a high gain and the robust sliding mode control (SMC) as well [1]. The advanced control methods of induction motors allows to reach the dynamic properties very similar with previously used the DC motors [2], but with significantly smaller maintenance requirements. The vector-field oriented control is achieved by adjusting the magnitude and angular frequency of rotor flux linkage [3]. It means that the rotor flux linkage must be adjusted synchronously with the reference frame and the magnitude must be controlled by stator currents on a constant value [4]. The actually position of rotor flux linkage vector (known is required for vector oriented control) can be estimated by the use of extended Kalman filter [5]. Control variables are the reference frame angular velocity and components of the stator current vector. State variables are the rotor angular velocity and components of the rotor flux vector. II. MATHEMATICAL MODEL OF INDUCTION MOTOR An induction motor is a generally complex non-linear subsystem, which can be described in orthogonal coordinate system d,q synchronously rotating with the reference frame by the following equations [6]: Voltage equations s s s s s s t R Ψ Ψ i u ω j d d + + = (1) r sk r r r r t R Ψ Ψ i u ω j d d + + = (2) Flux linkage equations r m s s s L L i i Ψ + = (3) s m r r r L L i i Ψ + = (4) Electromagnetic torque { } r s e p m Ψ i * Im 2 3 = (5) where u s is the stator voltage vector [V], u r – the rotor voltage vector (for squirrel cage rotor u r = 0) [V], i s – the stator current vector [A], i r – the rotor current vector [A], Ψ s – the stator flux linkage vector [Wb], Ψ r – the rotor flux linkage vector [Wb], R s – the stator resistance [Ω], R r – the rotor resistance [Ω], L s – the stator self inductance [H], L r – the rotor self inductance [H], L m – the mutual inductance [H], p – the number of poles [-], Im – the imaginary number, *– the complex conjugate, ω s – the reference frame angular velocity [rad.s -1 ], ω sk – the slip angular velocity [rad.s -1 ]. When the stator current is explicitly known, it is evident that only the rotor circuit voltage equations are required to describe the dynamic behavior of the electrical part of the induction motor. Then the stator current can be considered as a control input to the rotor circuit. If we express the rotor currents from (4) s r m r r r L L L i Ψ i - = 1 (6) 978-1-4577-1868-7/12/$26.00 ©2012 IEEE 137