Direct speed-flux vector control of induction motors: controller design and experimental robustness evaluation

Abstract

The paper presents a general theoretical solution oftheinduction motor speed-fluxdirect vector control, which is based on the second Lyapunov method application. The structure of the direct vector control algorithm involves the use of anyasymptotic flux observer with exponential stability properties. Suchapproach led to improvement of the vector control system robustness properties. A constructive procedure for the designof correction termsof the rotor flux observer is proposed.Designed family of the flux ob-servers guarantees the exponential stability and robustification with respect ofparametric disturbances. It is shown that the proposedsolution guarantees: global exponential trackingof the speed-flux reference trajectories together with asymptotic field orientation, asymptotic exponential estimation of the rotor flux, as well as asymptotic decoupling of torque (speed) and flux control. Comparative experimental study shows that new controller providesstabilization of the control performancesas well as efficiency at nominal levelwhen the rotor active resistance changes. The proposed direct vector control structures can be used for the development of energy-efficient high performanceinduction motor drives for metalworking, packaging equipment, modern electric transport and special equipment.