Mohamed Jemli

Geographic Distribution of MERS Coronavirus among Dromedary Camels, Africa

We found serologic evidence for the circulation of Middle East respiratory syndrome coronavirus among dromedary camels in Nigeria, Tunisia, and Ethiopia. Circulation of the virus among dromedaries across broad areas of Africa may indicate that this disease is currently underdiagnosed in humans outside the Arabian Peninsula.

Sensorless Indirect Stator Field Orientation Speed Control for Single-Phase Induction Motor Drive

The industrial requirements for the control of an induction machine without a mechanical sensor continue to be of interest, as evidenced by the most recent publications. The focus is on improvements of control without a mechanical sensor. A new method for the implementation of a sensorless indirect stator-flux-oriented control (ISFOC) of a single-phase induction motor (SPIM) drive is proposed in this paper. The proposed method of rotor speed estimation is based only on the measurement of the main and auxiliary windings stator currents and that of a reference q-axis current generated by the control algorithm. The error of the measured q-axis current from its reference value feeds the proportional plus integral controller, the output of which is the estimated slip angular frequency. Experimental results for sensorless ISFOC speed control of a SPIM drive are presented and analyzed using a dSPACE system with DS1104 controller board based on the digital signal processor TMS320F240. Digital simulation and experimental results are presented to show the improvement in performance of the proposed sensorless algorithm.

Real-time implementation of IRFOC for Single-Phase Induction Motor drive using dSpace DS 1104 control board

Abstract Single Phase induction Motors (SPIMs) are one of the widely used motors in the world. This explains the interest accorded by researchers on the improvement of the quality and performances of these motors. The availability of low-cost static converters makes possible the economic use of energy and improvement of the quality of the electromagnetic torque in the SPIM. Nowadays, Indirect Rotor-Field-Oriented Control (IRFOC) techniques brought on a renaissance in modern high-performance control of PWM inverter fed SPIM. In this paper, an IRFOC system is proposed for SPIMs including a relatively simple and effective decoupling scheme. This is achieved by introducing two new decoupling signals to the system. However, model asymmetry in SPIMs causes extra coupling between two stator windings. To use the field orientation control, the asymmetry must be eliminated by using an appropriate variable changing. A computer simulation of the IRFOC for Single-Phase Induction Motor drive is carried out to test the validity of the proposed method at nominal and zero speed. The design, analysis, and implementation for a 1.1-kW Single-Phase Induction Motor are completely carried out using a dSPACE DS1104 digital signal processor (DSP) based real-time data acquisition control (DAC) system, and MATLAB/Simulink environment. Digital simulation and experimental results are presented to show the improvement in performance of the proposed algorithm.

Doubly fed induction generator (DFIG) in wind turbine modeling and power flow control

In this work, the doubly fed induction generator (DFIG) for wind energy conversion system is studied. First, the dq model of the wound rotor induction machine in rotor reference frame and then how it can be implemented in simulink for fast simulations. In order to control the power flowing between the stator of (DFIG) and the grid, a control law is synthesized using PI controllers. Simulation results have demonstrated its excellent performances, with stator flux orientation control (SFOC).

Development and Experimental Evaluation of a Sensorless Speed Control of SPIM Using Adaptive Sliding Mode-MRAS Strategy

The aim of this paper is to provide a high-performance sensorless control of single phase induction motor drives. The synthesis of second-order sliding mode controllers to drive the rotor speed and the stator currents is based on the adaptive super twisting algorithm. The proposed method for the estimation of speed is based on sliding mode model reference adaptive system (SM-MRAS) observer. Whereas, in order to disturbance and uncertainties cancellation, an adaptive time varying switching gain is designed then adopted. A discrete low pass filter was used to improve the estimator generated signal for practical implementation, representing a very simple design process compared with other chattering reduction methods as adding an observer. The stability of the SM-MRAS speed estimation algorithm is proved using the Lyapunov approach and its robustness is investigated under load conditions. Simulation and experimental results prove the effectiveness of the proposed sensorless speed control algorithm.

Dspace based experimental results of indirect field oriented control (IFOC) PWM VSI fed induction motor

The aim of this paper is to present a full-digital implementation of indirect field oriented controlled (LFOC) induction motor drive with a Dspace DS 1102 hardware and software and Matlab simulink environment.

Première étude sérologique de la prévalence d’ Anaplasma phagocytophilum chez le dromadaire ( Camelus dromedarius ) en Tunisie

The aim of the study was to evaluate the seroprevalence of Anaplasma phagocytophilum in dromedary (Camelus dromedarius). Sera of 226 healthy dromedaries from three regions of Tunisia (Sidi Bouzid, Bouficha and Douz) were tested by indirect immunofluorescence (IFA). The overall infection rate was estimated at 29.2%. The study of risk factors showed that region, age, gender, presence of ticks and types of breeding had no influence on the seroprevalence of A. phagocytophilum. This study indicates for the first time in Tunisia that dromedary may be involved in the natural cycle of A. phagocytophilum.

Fail-safe digital implementation of indirect field oriented controlled induction motor drive

Abstract The aim of this paper is to present a full-digital implementation of indirect field oriented controlled (IFOC) induction motor drive with a personal computer (PC) and as much standardized hardware as possible. The complex functions required by IFOC induction motor drive have been executed by PC on line. Computer simulations of the IFOC induction motor drive with tuning rotor resistance have been carried out to test the validity of the proposed method at nominal and zero speed. For the experimental prototype, we use a current regulated-pulse width modulated-voltage source inverter (CR-PWM-VSI) fed induction motor drive. Experimental results of the IFOC induction motor drive obtained on a PC-based system are presented.

Implementation of Improved Sliding Mode Observer and Fault Tolerant Control for a PMSM Drive

This paper presents the development and experimentation of Fault-Tolerant Control (FTC) for sensorless Permanent Magnet Synchronous Motor (PMSM) drive with stator resistance tuning. In the fault-tolerant inverter, a redundant leg is added to replace the faulted leg. Consequently, the proposed inverter is a modified topology inverter with fault-tolerant capability, which can be configured as 3-phase 8-switch inverter. The detection of the faulty leg is based only on the output inverter currents measurement. To make toggle to a redundant leg in case of fault occurrence, a Fault Detection and Isolation (FDI) algorithm is proposed in this paper. Experimental results are presented using a 1.4kW, three poles three-phases PMSM. These results show that the proposed FDI algorithm is able to detect and to isolate the open-phase fault in PMSM drive.

Rotor time constant identification in vector controlled induction motor applied flux model reference adaptive system (MRAS)

The indirect field-oriented control (IFOC) technique brought on a renaissance in modern high-performance control of PWM inverter fed induction motor drives. This method requires the actual value of the rotor time constant which is used to calculate the magnitude and the position of the rotor flux. This value varies widely with rotor temperature and flux level of the machine. So, the quality of the drive system decreases if no means for compensation or identification is applied. This paper describes a rotor time constant identification method in order to update control gains of a vector controlled induction motor. A flux model reference adaptive system (MRAS) is used to estimate the inverse rotor time constant by only using measurements of the stator voltages and currents and rotor speed of an induction motor. The estimated rotor time constant is used as feedback in a vector speed control system for voltage-controlled pulse width modulation (PWM) inverter fed induction motor. The proposed method identifies the inverse rotor time constant with a good accuracy at any load and speed references. Simulation results point out the validity of the proposed method.<<ETX>>