MRAS-Based Super-Twisting Sliding-Mode Estimator Combined With Block Control and DTC of Six-Phase Induction Motor for Ship Propulsion Application

This article presents the block control (BC) approach combined with the direct torque control (DTC) through employing a model reference adaptive system (MRAS) based on the super-twisting sliding-mode (STSM) speed estimator of a six-phase induction motor (6PIM) for ship propulsion application. The BC is a robust speed controller that is employed for regulating the 6PIM speed. The closed-loop approach is designed in an
αβ
-reference frame as well as is based on the linearization BC approach. The flux estimator is based on the super-twisting technique that is a second-order sliding-mode approach. This observer is utilized as a reference model throughout the MRAS-based speed estimator for discarding the chattering problem of the conventional sliding-mode technique. Two STSM controllers are used for controlling the torque along with the stator flux and improving the drive system performance throughout external load disruptions. Furthermore, the STSM estimator estimates the torque and stator flux in a robust response with discarding the chattering problem. The proposed MRAS-based STSM speed estimator performance is investigated experimentally for the 750-W 6PIM as well as compared with the traditional DTC approach throughout various speed references, load disruptions, and low-speed command/low loading torque conditions.