Abdallah Zegaoui

R dson behavior in various MOSFET families

MOSFET are widely used for energy conversion and are must appropriated to photovoltaic systems up to 200VDC. Efficiency of these systems is very critical point. Efficiency of converters is mainly related to losses of its components and the MOSFET appears as one the main original. for the conversion of energy, it is very important to insure the higher efficiency as possible. In a first approach we studied MOSFET used in a switching mode. The losses in the transistor are directly linked to the Rdson value. As anterior studies have shown a linear dependence between the Rdson and the voltage supported by the transistor, we can predict a linear increasing of the losses for high output voltage. Our investigations clearly show that the MOSFET losses are greater than they would have to be, especially for high voltages, and our investigations on a large sample of transistors families clearly shows that this law have to be revisited. Indeed simulations show an increase much faster than expected of losses when voltage Vds increases. After compiling data on many power MOSFETs family data sheets a new behavioral model, including the fast evolution of Rdson, for high voltage, has been purposed. This model includes two parameters to be adjusted to a given MOSFET family and which make possible the losses calculation of the concerned family.

Enhanced model of photovoltaic cell/panel/array considering the direct and reverse modes

This paper presents an improved generalized physical model for photovoltaic, PV cells, panels and arrays taking into account the behavior of these devices when considering their biasing existing in direct and reverse modes. Existing PV physical models generally are very efficient for simulating influence of irradiation changes on the short circuit current but they could not visualize the influences of temperature changes. The Enhanced Direct and Reverse Mode model, named EDRM model, enlightens the influence on the short-circuit current of both temperature and irradiation in the reverse mode of the considered PV devices. Due to its easy implementation, the proposed model can be a useful power tool for the development of new photovoltaic systems taking into account and in a more exhaustive manner, environmental conditions. The developed model was tested on a marketed PV panel and it gives a satisfactory results compared with parameters given in the manufacturer datasheet.

Distributed photovoltaic architecture powering a DC bus: Impact of duty cycle and load variations on the efficiency of the generator

This paper focuses on a photovoltaic generator feeding a load via a boost converter in a distributed PV architecture. The principal target is the evaluation of the efficiency of a distributed photovoltaic architecture powering a direct current (DC) PV bus. This task is achieved by outlining an original way for tracking the Maximum Power Point (MPP) taking into account load variations and duty cycle on the electrical quantities of the boost converter and on the PV generator output apparent impedance. Thereafter, in a given sized PV system, we analyze the influence of the load variations on the behavior of the boost converter and we deduce the limits imposed by the load on the DC PV bus. The simultaneous influences of 1- the variation of the duty cycle of the boost converter and 2- the load power on the parameters of the various components of the photovoltaic chain and on the boost performances are clearly presented as deduced by simulation.This paper focuses on a photovoltaic generator feeding a load via a boost converter in a distributed PV architecture. The principal target is the evaluation of the efficiency of a distributed photovoltaic architecture powering a direct current (DC) PV bus. This task is achieved by outlining an original way for tracking the Maximum Power Point (MPP) taking into account load variations and duty cycle on the electrical quantities of the boost converter and on the PV generator output apparent impedance. Thereafter, in a given sized PV system, we analyze the influence of the load variations on the behavior of the boost converter and we deduce the limits imposed by the load on the DC PV bus. The simultaneous influences of 1- the variation of the duty cycle of the boost converter and 2- the load power on the parameters of the various components of the photovoltaic chain and on the boost performances are clearly presented as deduced by simulation.

The DoE method as an efficient tool for modeling the behavior of monocrystalline Si-PV module

The objective of this paper is to apply the Design of Experiments (DoE) method to study and to obtain a predictive model of any marketed monocrystalline photovoltaic (mc-PV) module. This technique allows us to have a mathematical model that represents the predicted responses depending upon input factors and experimental data. Therefore, the DoE model for characterization and modeling of mc-PV module behavior can be obtained by just performing a set of experimental trials. The DoE model of the mc-PV panel evaluates the predictive maximum power, as a function of irradiation and temperature in a bounded domain of study for inputs. For the mc-PV panel, the predictive model for both one level and two levels were developed taking into account both influences of the main effect and the interactive effects on the considered factors. The DoE method is then implemented by developing a code under Matlab software. The code allows us to simulate, characterize, and validate the predictive model of the mc-PV panel. The calculated results were compared to the experimental data, errors were estimated, and an accurate validation of the predictive models was evaluated by the surface response. Finally, we conclude that the predictive models reproduce the experimental trials and are defined within a good accuracy.

Development and optimization of a matrix converter supplying an electronic ballast - UV lamp system for water sterilization

Electronic ballasts dedicated to discharge lamps allow improving the quality of radiation by operating at high frequency. In the present work, the use of a single-phase direct converter with a matrix structure for supplying a low-pressure mercury-argon UVC lamp for water sterilization is proposed. The structure of the converter is based on two switching cells allowing the realization of a fully controllable bidirectional switches. The advantages of such a matrix topology include the delivered of a sinusoidal waveform current with a controllable power factor close to unity, variable in amplitude and frequency. In order to obtain the desired amplitude and frequency, a PWM control was associated in the current realization. Finally, a linear adjustment of the lamp arc current was warranted by using of a PI regulator.Electronic ballasts dedicated to discharge lamps allow improving the quality of radiation by operating at high frequency. In the present work, the use of a single-phase direct converter with a matrix structure for supplying a low-pressure mercury-argon UVC lamp for water sterilization is proposed. The structure of the converter is based on two switching cells allowing the realization of a fully controllable bidirectional switches. The advantages of such a matrix topology include the delivered of a sinusoidal waveform current with a controllable power factor close to unity, variable in amplitude and frequency. In order to obtain the desired amplitude and frequency, a PWM control was associated in the current realization. Finally, a linear adjustment of the lamp arc current was warranted by using of a PI regulator.

Multiphase Wind Energy Conversion Systems Based on Matrix Converter

This paper presents a new variable speed wind energy conversion systems (WECS). It is based on a six-phase asymmetrical squirrel cage induction generator (SCIG) and a matrix converter (MC) as power electronic interface between six-phase SCIG and electrical network. The analysis employs a rotor flux vector control algorithm and a scalar strategy modulated MC to control the generator. Characteristics of MC are used for maximizing the power tracking control when different wind speeds and delivering powers to the grid are simultaneously considered. The MC provides sinusoidal input and output voltages and a unity power factor, but causes an asymmetry in the generator. A current control strategy including the method of suppressing imbalance caused by this asymmetry is discussed. Some numerical simulations are carried out showing the effectiveness of the proposed WECS topology.