Experimental study of sensorless direct torque control for induction motor based on Enhanced Second Order Generalized Integrator-Frequency Locked Loop

This paper presents a cost-effective solution for speed estimation in induction motor system using the enhanced second-order generalized frequency-locked loop (ESOGI-FLL) technique as an estimator. The proposed solution delivers precise motor speed estimation, thanks to the inclusion of an FLL filter in the estimator. Additionally, this method is cost-effective in practice, requiring only a single current or voltage sensor, which is a significant improvement over traditional estimators that often need multiple sensors. Furthermore, the estimator is both easy to implement and maintain. It enhances performance by using the ESOGI technique to effectively estimate rapidly changing frequencies while also addressing the effects of DC disturbances and harmonics. The stability study of the proposed ESOGI-FLL technique has been successfully conducted based on lyapunov method. The proposed sensorless control has been experimentally tested and works effectively across a wide range of scenarios such as speed change tracking, load change as well as speed reversal scenario, resulting in good performance of the induction motor.