Bio: Hafaifa Ahmed is an academic researcher. The author has contributed to research in topics: Inverter & Pulse-width modulation. The author has an hindex of 3, co-authored 7 publications receiving 41 citations.
TL;DR: An estimation method of the motor internal parameters such as the rotor resistance, the stator resistance and the magnetizing inductance, is proposed in this paper to improve the control performance, to reduce the computational complexity and to minimize the rotor speed estimation error.
01 Nov 2018
TL;DR: The originality of this contribution is to calculate the various alarms based on this system which used the determined vibration models in order to ensure a reliable and safe operation of the gas compression installation using the examined gas turbine.
Abstract: Abstract During the gas turbine exploitation the presence of small defects can cause very high vibration amplifications, localized on the components of this rotating machine. For this, a diagnostic process is necessary for decision-making during the monitoring of failures caused by vibration phenomena, which consists in observing the system by comparing its current data with the data coming from a normal operation. These indicators help engineer to determine the symptoms for the failing components of the system. This work deals with problems related to these vibrations, with the aim of developing a system of detection of failures using dynamic neural networks approach. The originality of this contribution is to calculate the various alarms based on this system which used the determined vibration models in order to ensure a reliable and safe operation of the gas compression installation using the examined gas turbine.
17 Jan 2016
TL;DR: In this paper, the authors propose to study the gas turbine vibration behavior based on defect signal evaluation, an analysis made by the vibration signals measured, and show that the vibration effects observed provide a very powerful tool for protected the mechanical condition of the examined gas turbine.
Abstract: The vibration behavior of rotating machines is a very important industrial challenge, can cause aging and tiredness affect its components. In this work, we propose to study the gas turbine vibration behavior based on defect signal evaluation, an analysis made by the vibration signals measured. The tests results realized on the examined gas turbine shows that the vibration effects observed provide a very powerful tool for protected the mechanical condition of the examined gas turbine Keywords : Vibration behavior, rotating machines vibration analysis, gear defect evaluation, gas turbine, measures validation
••01 Sep 2019
TL;DR: This work details the method proposed for the prediction of the discharge of electric in the air by utilizing the Fuzzy Logic, a digital system capable of predicting discharges of electrical utilizing fuzzy reasoning.
Abstract: In this work we will detail the method proposed for the prediction of the discharge of electric in the air by utilizing the Fuzzy Logic (FL). The use of this technique has allowed us to have a digital system capable of predicting discharges of electrical utilizing fuzzy reasoning.. This fuzzy reasoning helped us to obtain results as will be detailed during this work to study this discharge. The difficulty of obtaining a mathematical model that can translate the evolution of the discharge of electric in the field of the high tension forced several researchers to introduce different analyzes and models to study such subject. In our paper we used the "fuzzy logic technique" based on the utilize of a fuzzy system to predict in a point-plane system the electrical discharge.
01 Nov 2018
TL;DR: In this article, a simple space vector pulse width modulation strategy is proposed to approximate the reference vector, and the calculation of dwell time becomes very simple, and simulation results are presented to verify the theoretical study of the system model.
Abstract: This paper presents the Space Vector Pulse Width Modulation technique (SVPWM) for Multilevel Cascaded H-Bridge Inverter (CHB Inverter) with a Resistive-Inductive Load (R-L Load) and an equal DC voltage source. Cascaded H-Bridge Inverter generate a large number of voltage vectors and redundant switching states, it create a problem of computational complexity in multilevel inverter. A simple space vector pulse width modulation strategy is proposed to approximate the reference vector, and the calculation of dwell time becomes very simple. Space Vector Modulation has a, numbers of features; good utilization of the DC-link voltage, low current ripple, low harmonic distortion (THD) and reduce switching losses. A three phase multilevel cascaded H-bridge Inverter has been constructed, and simulation results are presented to verify the theoretical study of the system model.
TL;DR: In this article , the authors present an overview of the state-of-the-art in fault-tolerant multiphase drive systems, focusing on phase/switch open-circuit failures.
Abstract: Multiphase drives offer enhanced fault-tolerant capabilities compared with conventional three-phase ones. Their phase redundancy makes them able to continue running in the event of faults (e.g., open/short-circuits) in certain phases. Moreover, their greater number of degrees of freedom permits improving diagnosis and performance, not only under faults affecting individual phases, but also under those affecting the machine/drive as a whole. That is the case of failures in the dc link, resolver/encoder, control unit, cooling system, etc. Accordingly, multiphase drives are becoming remarkable contenders for applications where high reliability is required, such as electric vehicles and standalone/off-shore generation. Actually, the literature on the subject has grown exponentially in recent years. Various review papers have been published, but none of them currently cover the state-of-the-art in a comprehensive and up-to-date fashion. This two-part paper presents an overview concerning fault tolerance in multiphase drives. Hundreds of citations are classified and critically discussed. Although the emphasis is put on fault tolerance, fault detection/diagnosis is also considered to some extent, because of its importance in fault-tolerant drives. The most important recent advances, emerging trends and open challenges are also identified. Part 1 provides a comprehensive survey considering numerous kinds of faults, whereas Part 2 is focused on phase/switch open-circuit failures.
TL;DR: A comprehensive literature review was necessary to re-evaluate the work done by the research community in the appropriate domains and this review article aims to cover all the relevant domains needed to be understood before proceeding towards the development of an acoustics-based fault diagnostic framework for an aircraft APU.
TL;DR: The obtained results confirm and validate the ability of the proposed control procedure in achieving a robust dynamic performance of the drive against the system uncertainties such as parameter variation.
Abstract: This paper aims to develop an innovative sensorless control approach for a five-phase induction motor (IM) drive. The operation principle of the sensorless scheme is based on the sliding mode theory, within which a sliding mode observer (SMO) estimates the speed and rotor resistance simultaneously. The operation methodology of the proposed control technique is formulated using the mathematical model of the machine and the two-time-scale approach. The observation technique offers a simple and robust solution of speed and rotor resistance estimation for the sensorless control approach of the multiphase drive. The paper considers the five-phase induction motor (IM) as a case study; however, the proposed control algorithm can be employed by different types of multiphase machines. To test the applicability of the proposed sensorless control approach, the drive performance is firstly validated using MATLAB/Simulink-based simulation. Then, the simulation results are verified using real-time simulation and experimentally using TMS320C32 DSP-based control board. The obtained results confirm and validate the ability of the proposed control procedure in achieving a robust dynamic performance of the drive against the system uncertainties such as parameter variation.
TL;DR: An original approach to gas turbine monitoring, based on the concept of fuzzy logic, is proposed, which shows the efficiency and robustness of the fuzzy gas turbine faults detection strategy and improves the operation of this turbine.
Abstract: Currently, the challenges of sustainable development in the operational safety of industrial systems continue to grow and increase, given the increasing complexity of these industrial installations. Through the recurrent development of better competitive performance in terms of quality, productivity, flexibility, robustness, and environmental impacts, which is essential in order to offer even more suitable and more accurate solutions to monitoring issues. In order to avoid the dangers that may arise because of the risks and dysfunctional faults of these systems, these risks require mastery of the monitoring systems inherent in this equipment. This work proposes an original approach to gas turbine monitoring, based on the concept of fuzzy logic, with practical implementations of this diagnosis strategy for vibration faults of this rotating machine. The proposed approach makes it possible to monitor the efficiency of the studied gas turbine in real-time and for substantial and substantive improvement in the operation of this turbine and to achieve the objectives in terms of operational safety and in terms of solutions' costs implemented for this type of machine. To this end, first fuzzy models associated with real behavior models of the examined turbine variables are developed, to identify and model the gas turbine dynamics used in a gas transport facility at Hassi R'Mel in southern Algeria, based on a fuzzy approach using experimental operating data from the rotating machine, in order to approximate the variables of this nonlinear system in the form of fuzzy rules and variables. Then, the fault diagnosis strategy of this turbine based on the generation of fault residues is carried out and tested in the presence and absence of disturbances, to validate the effectiveness of this fuzzy approach in terms of sensitivity and robustness of detection, location, and identification of faults. This work shows the efficiency and robustness of the fuzzy gas turbine faults detection strategy and improves the operation of this turbine. Likewise, has increased turbine work time, minimized downtime, and reduced the frequency of unscheduled downtime of this rotating machine.
09 Apr 2021
TL;DR: In this article, a sensorless field-oriented control (FOC) of an open-end stator winding five-phase induction motor (OESW-FPIM) is proposed, which combines a model reference adaptive system (MRAS) and a sliding mode (SM) observer.
Abstract: This paper proposes a sensorless field-oriented control (FOC) of an open-end stator winding five-phase induction motor (OESW-FPIM). The FOC technique used is associated with dual Space Vector Modulation (SVM) to provide a constant switching frequency and lower harmonics distortion. Furthermore, a simple hybrid observer is proposed which combines a model reference adaptive system (MRAS) and a sliding mode (SM) observer. The examined observer is designed for the estimation of the rotor flux and rotational speed as well as for the estimation of the load torque disturbances. Lyapunov theorem is used in this paper to prove the observer's stability. The work presented in this paper aims to enhance the researched motor's sensorless control and its robustness against external load disturbances and parameters variation. In the proposed MRAS-SM observer, the reference model is replaced by a SM model which uses a sigmoid function as a switching function to overcome the chattering problem. This combination is intended to make use of the advantages of both strategies. At the same time, to preserve the high-level performance of the sensorless FOC technique and to reduce system uncertainties, an estimation algorithm is developed to identify the rotor resistance and the stator resistance simultaneously during motor operation. The parameter estimation algorithm is combined with the proposed control to improve the speed estimation and control accuracy, particularly at low-speed operation. Finally, the effectiveness of the proposed control is validated in real-time by utilizing a hardware-in-the-loop (HIL) platform.