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1

Off-line robustification of Generalized Predictive Control for uncertain systems

Otmane K. K., Bali N., Nezli L.

Archives of Control Sciences

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2014

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Vol. 24, no. 4

499--513

EN

An off-line methodology was proposed for enhancing the robustness of an initial Generalized Predictive Control (GPC) by convex optimization of the Youla parameter. However, this procedure of robustification is restricted with the case of the systems affected only by unstructured uncertainties. This paper proposes an extension of this method to the systems subjected to both unstructured and structured polytopic uncertainties. The main idea consists in adding supplementary constraints to the optimization problem which validates the Lipatov stability condition at each vertex of the polytope. These polytopic uncertainties impose a set of non convex quadratic constraints. The globally optimal solution is found by means of the GloptiPoly3 software. Therefore, this robustification provides stability robustness towards unstructured uncertainties for the nominal system, while guaranteeing stability properties over a specified polytopic domain of uncertainties. Finally, an illustrative example is given.

2

A modified PWM three intervals control for a matrix converter in real time

Rezaoui M. M., Nezli L., Mahmoudi M. O., Kouzou A., Abu Rub H.

Archives of Control Sciences

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2014

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Vol. 24, no. 1

85--98

EN

In this paper, the application of the proposed control strategy PWM three intervals with 3×5 matrix converter is presented and analyzed. This control strategy is developed for the control of the multi-phases matrix converter, where the main aim is to ensure the waveform quality of the output voltages and the input currents based on the THD evaluation. Simulation results and real time implementation on dSpace 1103 of 3×5 matrix converter under R-L load are presented for the validation of the proposed control strategy and to clarify the main related advantages.

3

Backstepping/DTC control of a double star synchronous machine drive

Boudana D., Nezli L., Tlemcani A., Mahmoudi M. O., Djemai M., Tadjine M.

Archives of Control Sciences

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2010

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Vol. 20, no. 2

227-247

EN

Direct torque control (DTC) allows for very high quality torque control without a need for current controllers tuning or using coordinate transformation. However, barge torque ripples arise as well as inconstant inverter switching frequency due to the hysteresis of comparators. This paper present a backstepping/DTC control based on the space vector modulation (SVPWM) for double star synchronous machine (DSSM) to reduce the torque, flux, current and speed pulsations during steady state. By the coordinate transformation the DSSM models are presented in view of control. Then a conventional DTC is developed to get a decoupled system and a PI controller is designed to control the speed. To improve the static and dynamic control performance of the DSSM, the speed controller is designed using a backstepping/DTC procedure in conjunction with SVPWM. Simulation results with the conventional DTC and proposed backstepping/DTC are presented and compared. Results show the effectiveness and the robustness of the approach proposed.

4

On sliding mode based non linear PID design for position control of permanent magnet synchronous machine with unknown load torque

Nezli L., Tadjine M., Boucherit M. S.

Archives of Control Sciences

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2006

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Vol. 16, no. 1

71-86

EN

This paper presents a new control design procedure for permanent magnet synchronous machine motion drive in the case of unknown load torque. The contol law is based on the combination of sliding mode, non linear proportional integral derivative regulators, and the backstepping approaches. More precisely, we determine the controllers imposing the current-position tracking in three recursive steps and by using appropriate sliding mode / PID gains that are non linear functions of the system state. Moreover, a comparative study between the proposed sliding mode PID/Backstepping approach and the feedback linearizing control is made by realistic simulation including load torque change, parametric variations and measurement noise. The results of current-position tracking show the effectiveness of the proposed method in presence of strong disturbances.