Fuzzy sliding mode controller

By using the direct torque control (DTC), robust response in ac drives can be produced. Ripples of currents, torque and flux are oberved in steady state. space vector modulation (SVM) applied in DTC and used for a sensorless induction motor (IM) with fuzzy sliding mode speed controller (FSMSC) is studied in this paper. This control can minimize the torque, flux, current and speed pulsations in steady state. To estimate the rotor speed and stator flux the model reference adaptive system (MRAS) is used that is designed from identified voltages and currents. The FSMSC is used to enhance the efficiency and the robustness of the presented system. The DTC transient advantage are maintained, while better quality steady-state performance is produced in sensorless implementation for a wide speed range. The drive system performances have been checked by using Matlab Simultaion, and successful results have been obtained. It is deduced that the proposed control system produces better results than the classical DTC. Keywords: Direct torque control Fuzzy sliding mode controller Induction motor Model reference adaptive system Sensorless This is an open access article under the CC BY-SA license. 1. INTRODUCTION The asynchronous motor in the industrial applications has many advantages such as the robustness, its low cost, its performances and the maintenance simplicity. Power electronics and numerical control ensure today to consider the control of the variable speed. Applying the various technologies, the scientific developed different control approaches to overcome, in electrical machines, the flux and the torque. So, the situation has however changed dramatically with the advent of DTC [1] and speed sensorless control [2]. Since 1985, the DTC was completly used for induction motor. The torque and the flux have to be correctly estimated. A correct estimation of the torque and the flux enable DTC to develop fast torque and flux control [3]. After all, torque, flux, and current pulsations occur in steady state operation. They are reproduced in torque, flux and speed estimation. To overcome some of the desavantages of DTC, many techniques have been proposed [4, 5]. Among these solutions proposed: DTC with Space Vector Modulation (DTC-SVM) [6, 7]; DTC based on artificial intelligence techniques [8, 9]. The need for sensorless speed control of induction machines has become requiered. The mechanical speed sensor needs maintenance in many application which make the sensor intallation difficult. For these advantages, most industry admit that the succeding production of commercial drives will use any type of sensorless control. For speed-sensorless DTC-IM drives many system have been proposed, which use stator currents and voltages measurements to estimate the mechanical speed.

Sliding mode control is a very attractive control scheme because of its robustness against both structured and unstructured uncertainties as well as external disturbances. In this way, it has been widely employed for the dynamic positioning of remotely operated underwater vehicles. Nevertheless, in such situations the discontinuities in the control law must be smoothed out to avoid the undesirable chattering

In this work we are interested to discrete robust fuzzy sliding mode
control. The discrete SISO nonlinear uncertain system is presented by the TakgiSugeno type fuzzy model state. We recall the principle of the sliding mode control
theory then we combine the fuzzy systems with the sliding mode control technique
to compute at each sampling time the control law. The control law comports two
terms: equivalent control law and switching control law which has a high frequency.
The uncertainty is replaced by its upper bound. Inverted pendulum and mass spring
dumper are used to check performance of the proposed fuzzy robust sliding mode
control scheme.

Sliding mode control is a very attractive control scheme because of its robustness against both structured and unstructured uncertainties as well as external disturbances. In this way, it has been widely employed for the dynamic positioning of remotely operated underwater vehicles. Nevertheless, in such situations the discontinuities in the control law must be smoothed out to avoid the undesirable chattering

Sliding mode control, due to its robustness against modelling imprecisions and external disturbances, has been successfully employed to the dynamic positioning of remotely operated underwater vehicles. In order to improve the performance of the complete system, the discontinuity in the control law must be smoothed out to avoid the undesirable chattering effects. The adoption of a properly designed thin boundary

In this paper, an adaptive fuzzy sliding-mode controller (AFSMC) is proposed to control SMA actuator. An approach of self-tuning fuzzy sliding-mode control which combines fuzzy control with the sliding-mode control (SMC), is presented for the tracking control of a class of nonlinear systems with the parameter uncertainties. Based on Lyapunov theory, the asymptotic stability of the overall systems is proved.