A New Model Reference Adaptive Controller for Four Quadrant Vector Controlled Induction Motor Drives

In this paper, a new model reference adaptive controller (MRAC) for the speed estimation of the vector-controlled induction motor drive is presented. The proposed MRAC is formed using instantaneous and steady-state values of X (
$=\vec{v}^{\ast} \times \vec{i}$
where
$v = \hbox{voltage}$
and
$i = \hbox{current}$
vector in synchronously rotating reference frame), which is a fictitious quantity and has no physical significance. This formulation is not only simply realizable but also made the sensorless drive stable in all the four quadrants of operation. Speed estimation does not involve computation of stator or rotor flux. Requirement of no additional sensors makes the drive suitable for retrofit applications. A simple modification of the controller can estimate the stator resistance in all the four quadrants of operation, if speed signal is available. The proposed MRAC-based speed sensorless vector control drive as well as the stator resistance estimation technique has been simulated in MATLAB/SIMULINK and experimentally validated through a dSPACE-1104-based laboratory prototype. A study on stability of such systems is also added.