Adaptation of Slip Gain for Modified Transient Vector Estimator-Based Speed Control of Induction Machine Drive

Modified transient vector estimator (MTVE)-based speed control scheme that combines the high transient performance features of rotor field-oriented control with the robustness features of scalar control is presented in the literature. However, the MTVE scheme involves the calculation of slip gain to obtain torque reference. Either inaccurate estimation or variation in the estimated slip gain can result in the degradation of performance of MTVE control. In order to overcome this problem, this article proposes a slip gain adaptation scheme that is independent of speed of operation. The proposed method uses the
$d$
-axis component of stator voltage to obtain the expression for disorientation factor and works by matching all the control side variables with that of actual machine variables and uses a simple proportional-integral (PI) controller to implement slip gain adaptation. The impact of inaccurate slip gain estimate on the
$dq$
-components of various currents, voltages, feedforward components, and the torque and flux of the machine is analyzed in this article. The proposed adaptation scheme is suitable for wide speed range operation, in contrast to the existing slip gain adaptation methods, where the open-loop gain is dependent on the synchronous frequency information. The proposed adaptation scheme is validated using the detailed simulation and experimental results. A comparison of the proposed adaptation method with the existing methods is also presented in this article.