The evolution of the modern technologies and the development of power electronics has led to the extensive use of DC-DC Buck-Boost converters in the application of power amplifier, battery management system, self-regulating power supplies etc, as they have higher output voltage and low operating duty cycle. The problem of degradation in adeptness of the Buck-Boost converters in presence of a load and lumped parameter uncertainties are analyzed. An Extended High Gain Observer is formulated to estimate the output voltage, load current, and its first derivative which is considered to be nonlinear and bounded. The reference current is compared with the estimated load current, forming a sliding surface. Sliding Mode Controller ensures convergence of estimated load current trajectories to reference current trajectories in finite time. Finally, an inner control loop generates a duty ratio resulting in output voltage which tracks the required reference voltage. The simulation results have been implemented in MATLAB/Simulink to validate fast estimation of load current, output voltage and disturbance rejection in a closed-loop process.

Extended High Gain Observer based Control Design for Buck-Boost Converters

Solar panels have a nonlinear voltage-current characteristic, with a distinct maximum power point (MPP), which depends on the environmental factors, such as temperature and irradiation. In order to continuously harvest maximum power from the solar panels, they have to operate at their MPP despite the inevitable changes in the environment. Various methods for maximum power point tracking (MPPT) were developed and finally implemented in solar power electronic controllers to increase the efficiency in the electricity production originate from renewables. In this paper we compare using Matlab tools Simulink, two different MPP tracking methods, which are, fuzzy logic control (FL) and sliding mode control (SMC), considering their efficiency in solar energy production.

Maximum power point tracking algorithm based on sliding mode and fuzzy logic for photovoltaic sources under variable environmental conditions

A pulse width modulation DC - DC converter. A pulse width modulation DC - DC converter comprising: a switch unit, the switch unit converting an input voltage into an output voltage; proportional integral derivative controller, the PID controller generates a voltage proportional integral derivative control; comparator which comparator generates a control voltage switch; the switch control switch controller, the switch controller provides the switching control signal to the switching unit, turns on the charge switch in the oN period of the switching control voltage and switches off the discharge at the same time, and in the voltage-off period of switch off the charging and discharging switches are simultaneously turned on; and a compensation unit operating point, the operating point in response to the operating point compensation unit operates the compensation signal and to provide a uniform predetermined node during the initial driving period electrical initialization voltage levels.

A pulse width modulation DC - DC converter

Le travail de cette these porte sur la synthese de systemes de commande robuste pour des convertisseurs electriques, en utilisant le principe des modes glissants (commande a structure variable). Les convertisseurs electriques sont par nature des systemes dont la structure varie (commutation d'interrupteurs), par consequent la technique des modes glissants s'adapte bien au fonctionnement de ces convertisseurs. Dans un premier temps, ce type de commande est synthetise pour un onduleur realise a partir d'un abaisseur reversible en courant et en tension. Des resultats de simulation et experimentaux confirment le bien fonde de la theorie developpee. Dans un deuxieme temps, une extension du champ d'application de la technique des modes glissants a ete effectuee sur un convertisseur serie resonnant pont complet. Celui-ci presente des caracteristiques non lineaires. Cependant, sous certains conditions de fonctionnement du convertisseur serie resonnant et avec un choix approprie des variables d'etat, le convertisseur serie resonnant se comporte comme un abaisseur conventionnel. Par les resultats de simulation, nous montrons l'interet de cette technique de commande pour ce type de convertisseur. Le bilan de ce travail permet de proposer la technique de commande par modes glissants pour des convertisseurs electriques, car il a ete montre en particulier, la robustesse de cette commande meme en presence des fortes perturbations, tant sur la charge que sur la tension source

Commande par mode de glissement. Application aux convertisseurs electriques

In this article, we are going to do a study that consist in the configuration of a link between an earth station to broadcast multimedia service and a user of this service via a geostationary satellite in Kaband and the set up of the different components of this link and then to make the calculation of the link budget for this system. The application carried out in this work, allows us to calculate the link budget in both directions: the uplink and downlink, as well as all parameters used in the calculation and the development of a link budget. Finally, we will try to verify using the application developed the feasibility of implementation of this system.

Configuration and the Calculation of Link Budget for a Connection via a Geostationary Satellite for Multimedia Application in the Ka Band

This paper is a simple and systematic approaches to the design of sliding mode controller for buck DC-DC Converters. Various aspects of the design, including the practical problems and the proposed solutions, are detailed. However, these control strategies can't compensate for large load current and input voltage variations. In this paper, a new control strategy by compromising both schemes advantages and avoiding their drawbacks is proposed, analyzed and simulated.

Sliding mode controller for buck DC-DC Converter

In this article, we will carry out the calculation for the power budget for a connection between a station of reception and a geostationary satellite, while stressing a phenomenon which influences the power budget which is the "phenomenon of antenna depointing" and that for both segments: ground and space.

The application enables us to consider the losses caused by this phenomenon on the power budget and its impact on our connection while passing by the two cases: depointing of the antenna on the ground, and the depointing of the antenna on board. Finally, we will try to draw up a comparative study to see which of the two antennas can be most affected.

Depointing influence of antenna on the link budget at the reception

On the September 26, 2016, Algeria's enhanced micro-satellite Alsat-1B was launched into a 680-km low Earth orbit onboard a PSLV-C35 rocket from Sriharikota near the metropolis of Chennai (South India). The spacecraft was designed, manufactured, and launched as an 18-month long technology transfer program between the Algerian Space Agency (ASAL), Algeria and Surrey Satellite Technology Limited (SSTL), U.K. This article describes the design and in-orbit performance of the power system and the design of the Alsat-1B high-efficiency solar power system used to charge AEA Battery System Ltd and Société des Accumulateurs Fixes et de Traction Lithium-ion batteries. The solar power system described in this article is deployed on many satellites including Alsat-1b, which was launched from a heritage SSTL power system. It was implemented with a conventional pulsewidth modulator (PWM) duty cycle ratio control method to design and build a solar battery charger. Maximum power point tracking (MPPT) was used to maximize the output power, irrespective of the temperature of the solar arrays and irradiation conditions. The simulation results achieved by using Orcad/Pspice programs are in good agreement with the experimental results. These results demonstrate the reliability and validity of the implemented MPPT technique. The battery charger prototype was tested and the results obtained provided conclusions on the conditions of permanent control on the battery charger.

Mohammed Ali Mebrek

Papers

Sliding mode controller for buck DC-DC Converter

Depointing influence of antenna on the link budget at the reception

Power System Design and Performance for Low Earth Orbit Spacecraft

Depointing influence of antenna on the link budget at the reception

Depointing influence of antenna on the link budget at the reception