Anis Sellami

An H∞ Sliding Mode Observer for Takagi-Sugeno Nonlinear Systems with Simultaneous Actuator and Sensor Faults

Abstract This paper considers the problem of robust reconstruction of simultaneous actuator and sensor faults for a class of uncertain Takagi-Sugeno nonlinear systems with unmeasurable premise variables. The proposed fault reconstruction and estimation design method with H∞ performance is used to reconstruct both actuator and sensor faults when the latter are transformed into pseudo-actuator faults by introducing a simple filter. The main contribution is to develop a sliding mode observer (SMO) with two discontinuous terms to solve the problem of simultaneous faults. Sufficient stability conditions in terms linear matrix inequalities are achieved to guarantee the stability of the state estimation error. The observer gains are obtained by solving a convex multiobjective optimization problem. Simulation examples are given to illustrate the performance of the proposed observer

Control of saturated systems with sliding mode

This paper present a design methodology of sliding mode control of a class of linear saturated systems. The constraint of saturation is reported on the control vector. Firstly, we present the structure of saturation and the new formulation of the saturated state system. Secondly, the synthesis of the sliding surface is formulate as a problem of root clustering, which leads to the development of a continuous and non-linear control law that ensures the reaching condition of the sliding mode. Finally we present a numerical application to validate the theoretical concepts.

Three-phase grid-connected photovoltaic system with maximum power point tracking technique based on voltage-oriented control and using sliding mode controller

This paper presents a Matlab/Simulink model of grid connected photovoltaic (PV) system, including a PV array, a maximum power point tracking boost converter and a grid interactive, a control system. A space vector pulse width modulation (SVPWM) has been widely applied in the current control of three-phase voltage source inverters (VSI). The proposed system consists of two main controllers: a boost converter and a grid interactive voltage source inverter. The boost converter is used to regulate the PV voltage and track the MPP of PV array. A perturbation and observation (P&O) is used as MPPT method and it determines the system operation point according of rapidly changing atmospheric conditions. A cascaded control structure with an outer dc link voltage control loop and an inner current control loop is used. The currents are controlled in a synchronous orthogonal d, q frame using a decoupled feedback control. The reference current of proportional-integral (PI) d-axis controller is extracted from the dc-side voltage regulator by applying the energy balancing control. Furthermore, in order to achieve a unity power factor, the q-axis reference is set to zero. The SMC proposed in this paper, to control of current uses the integral sliding mode. Furthermore, classical controls PI compared with the SMC. The results show that the SMC technique is more suitable than that classical control (PI).

Behaviour of a high pressure sodium lamp fed by a pulsed power supply

The aim of this paper is to present the colorimetric and photometric results for a pulsed power supply operated high pressure sodium (HPS) lamp. Especially, we are interested in controlling the spectral response radiation of the yellow D line. This sodium D line is composed of two spectral components, one at 589.6 nm and the other at 589.0 nm. The pulsed power supply is a driver for the HPS lamp based on the application of a low frequency (50 Hz) square current waveform through the lamp with one or more pulses on each half cycle. A description is given of the physical modeling of the arc’s behaviour. Experimental results obtained from our laboratory power supply for a 400 W HPS lamp supplied at 50 Hz and simulations are shown.

Variable speed wind turbine control by discrete-time sliding mode approach.

The aim of this paper is to propose a new design variable speed wind turbine control by discrete-time sliding mode approach. This methodology is designed for linear saturated system. The saturation constraint is reported on inputs vector. To this end, the back stepping design procedure is followed to construct a suitable sliding manifold that guarantees the attainment of a stabilization control objective. It is well known that the mechanisms are investigated in term of the most proposed assumptions to deal with the damping, shaft stiffness and inertia effect of the gear. The objectives are to synthesize robust controllers that maximize the energy extracted from wind, while reducing mechanical loads and rotor speed tracking combined with an electromagnetic torque. Simulation results of the proposed scheme are presented.

Dimming control by variation of the switching frequency for high-intensity discharge lamps

In this paper, a high-frequency dimmable electronic power supply for the high-pressure sodium lamp is presented. The method includes a full bridge rectifier generating a dc-link voltage and a half bridge inverter to generate a frequency swept lamp power signal to drive the lamp while avoiding acoustic resonance. A dimming technique for a resonant circuit electronic ballast based on a variable frequency is introduced. In addition, the ability in the dimming range is demonstrated by experiments and simulation in order to verify the performance of the proposed circuit. A dimming range from 100% to 50% has been achieved. The efficiency is always higher than 89% and the ballast can accurately follow a fixed dimming plan.

Robust Delay-Derivative-Dependent Sliding Mode Observer for Fault Reconstruction: A Diesel Engine System Application

In this paper, a new delay-derivative-dependent sliding mode observer (SMO) design for a class of linear uncertain time-varying delay systems is presented. Based on this observer, a robust actuator fault reconstruction method is developed. In the meantime, the considered uncertainty is bounded and the time-delay is varying and affects the state system. Besides, the dynamic properties of the observer are analyzed and the reachability condition is satisfied. Applying the developed SMO, the

Sliding mode control of a photovoltaic pumping system

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