A new adaptive Direct Torque Control (DTC) scheme based-on SVM for adjustable speed sensorless induction motor drive

This paper describes a combination of Direct Torque Control (DTC) and Space Vector Modulation (SVM) for an adjustable speed sensorless induction motor (IM) drive. The motor drive is supplied by a two level FPGA-based SVPWM inverter. The inverter reference voltage is obtained based on input-output feedback linearization control, using the IM model in the stator d-q axes reference frame with stator current and flux vectors components as state variables. In addition, a conventional PI speed controller is employed to generate the reference torque signal. Moreover, a novel Lyapunov based nonlinear stator flux observer is developed which provides simultaneous estimation of the stator flux, rotor speed, and rotor and stator resistances. Finally, the effectiveness and validity of the proposed control approach is verified by computer simulation and experimental results.