Comparative Simulation Study of Luenberger and MRAS Observers for a Sensorless Induction Motor Drive Using a Five-Level NPC Inverter With ADRC-Based VC-DTC

This paper presents a simulation-based validation of an advanced sensorless control system for induction motors applied within an electrical training environment. The performance of the Luenberger observer and Model Reference Adaptive System (MRAS) is evaluated under dynamic conditions, enabling a comparative analysis of their noise-reduction capability and control effectiveness. To enhance regulation, the Active Disturbance Rejection Controller (ADRC) is introduced as an alternative to conventional proportional-integral controllers, supported by detailed mathematical formulation. Furthermore, a hybrid strategy combining vector control and direct torque control (DTC) is developed to address harmonic distortion in stator currents and torque ripple. The use of a five-level neutral point clamped (NPC) inverter allows sinusoidal voltage operation, contributing to improved speed regulation and torque performance. MATLAB/Simulink simulations validate the proposed approach, demonstrating reduced torque ripples, enhanced dynamic response, and improved overall system efficiency. The results highlight the strengths and limitations of observer-based and adaptive sensorless methods within this framework.