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

Abstract

The paper presents a general theoretical solution of the induction motor speed-flux direct vector control, which is based on the second Lyapunov method application. The structure of the direct vector control algorithm involves the use of any asymptotic flux observer with exponential stability properties. Such approach led to improvement of the vector control system robustness properties. A constructive procedure for the design of correction terms of the rotor flux observer is proposed. Designed family of the flux observers guarantees the exponential stability and robustification with respect of parametric disturbances. It is shown that the proposed solution guarantees: global exponential tracking of 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 provides stabilization of the control performances as well as efficiency at nominal level when the rotor active resistance changes. The proposed direct vector control structures can be used for the development of energyefficient high performance induction motor drives for metalworking, packaging equipment, modern electric transport and special equipment