Abdelkarim Ammar

Modified load angle Direct Torque Control for sensorless induction motor using sliding mode flux observer

Direct Torque Control is a control technique in AC drive systems to obtain high performance torque control. The conventional DTC utilizing hysteresis comparators suffers from high torque ripples and variable switching frequency. The most common solution to those problems is to use the space vector modulation. In this paper a modified direct torque control of induction motor scheme is presented. The modifications include torque and flux ripples reduction. This technique is known as SVM-DTC. It is based on stator flux orientation and space vector modulation (SVM). In the other hand this paper aims to design a sliding mode observer for speed/flux estimation which improves the control performances by using a sensorless algorithm in order to decrease the cost and reliability of the system. The theoretical principles, simulation and experimental results of sensorless control method are presented using Matlab/Simulink with real time environment using dSpace 1104.

Nonlinear SVM-DTC for induction motor drive using input-output feedback linearization and high order sliding mode control

This paper presents a nonlinear Direct Torque Control (DTC) strategy with Space Vector Modulation (SVM) for an induction motor. A nonlinear input-output feedback linearization (IOFL) is implemented to achieve a decoupled torque and flux control and the SVM is employed to reduce high torque and flux ripples. Furthermore, the control scheme performance is improved by inserting a super twisting speed controller in the outer loop and a load torque observer to enhance the speed regulation. The combining of dual nonlinear strategies ensures a good dynamic and robustness against parameters variation and disturbance. The system stability has been analyzed using Lyapunov stability theory. The effectiveness of the control algorithm is investigated by simulation and experimental validation using Matlab/Simulink software with real-time interface based on dSpace 1104.

Simulation and real-time implementation of sensorless field oriented control of induction motor at healthy state using rotor cage model and EKF

The vector control has been designed in order to achieve decoupled control between rotor flux and electromagnetic torque. The extended Kalman filter is a sensorless algorithm which allows estimating the state parameters and the rotor speed of the induction motor. This paper presents a sensorless control algorithm for induction motor drive. It consists of field oriented control and extended Kalman filter used for rotor speed estimation. The performances of this algorithm are tested and validated in simulation and experimental test bench in Matlab/Simulink environment with Real-Time interface based on the dSpace 1104.

Efficiency optimization for sensorless induction motor controlled by MRAS based hybrid FOC-DTC strategy

The Field Oriented Control (FOC) and the Direct Torque Control (DTC) are the well-known control strategies in the modern AC systems nowadays. However, both of them have a number of limits, such as the dependence on machine parameters of the vector control and the high ripples of DTC. This work presents a hybrid control strategy for induction motor (IM) based on the combining of the two techniques in order to benefit from their advantages and achieve high performance control. Besides, a Model Reference Adaptive System (MRAS) observer will be used for speed estimation to improve the reliability and decrease the cost of the control system. Furthermore, the IM energy optimization will be treated as the second objective of this paper. A proposed model based strategy will be used for loss minimization. This strategy bases on online adjusting of the rotor flux magnitude reference and choosing an optimal value for each applied load torque. The proposed algorithm will be investigated by simulation and experimental implementation by using Matlab/Simulink with real time interface (RTI) based on dSpace 1104 board.

Implementation of robust SVM-DTC for induction motor drive using second order sliding mode control

The AC drives direct torque control (DTC) is used to obtain high performance decoupled torque and flux control. The SVM based direct torque control is a common solution which used to solve the conventional DTCs problems such as the high torque ripples and variable switching frequency. However, this control technique bases on stator flux orientation and PI controllers. This paper aims to improve the SVM-DTC performance by replacing the PI controllers by high order sliding mode controllers. Theses controllers are based on second order super twisting strategy, they can overcome the classical PI problems which are represented in robustness against parameters variation and external disturbance. Furthermore, super twisting algorithm reduces the chattering effect and keep the same properties of the first order sliding mode control. Another point, this paper presents a design of load torque observer based on second order sliding mode control in order to estimate the load value and reduce the cost and the uncertainties of control system. The simulation and experimental results of robust SVM-DTC control method are presented using Matlab/Simulink with real time interface using dSpace 1104 bored.