Liste des documents
Fractional-Fuzzy PID Control Approach ofPhotovoltaic-Wire Feeder System (PV-WFS):Simulation and HIL-Based ExperimentalInvestigation
The utilization of solar photovoltaic (PV) generator as a power source for wire feedersystems (WFSs) of arc welding machines is one of the promising domains in solar PV applications. Thisarticle proposes a new type of welding WFS and investigates the PV penetrated energy systems. Theproposed system comprises of a solar PV generator, a DC/DC buck converter, and a permanent magnet DC(PMDC) motor. The power of the proposed standalone solar photovoltaic-wire feeder system (PV-WFS)can be widely improved using an intelligent fractional-order fuzzy proportional integral derivative (FOFuzzy-PID) regulator based on perturbing and observe (P&O) MPPT method. In this article, a FO-FuzzyPID regulator is also designed for a PMDC motor driven welding WFS system. Which will then control thewire feed rate of the welding WFS system. Furthermore, the dynamic reaction of the proposed solar PVWFS depends on the coefficients of these FO-Fuzzy-PID regulators, which are adjusted by a meta-heuristictuning algorithm based on particle swarm optimization (PSO) technique. The proposed strategy is testedusing MATLAB simulations and experimentally verified in real-time on a Hardware-in-the-loop (HIL)testing platform using a dSPACE®1104 board-based laboratory setup. Simulation and experimental resultsare acceptable and demonstrate the effectiveness, precision, stability, and dynamic reaction of the suggestedoptimized wire feeder regulating system and the considered intelligent P&O MPPT technique. Voir les détails
Mots clés : Buck converter, fractional-order fuzzy PID regulator, MPPT technique, PSO algorithm, PV module, wire feeder system (WFS).
An Enhanced MPPT Method CombiningFractional-Order and Fuzzy Logic PIDController for a Photovoltaic-Wire FeederSystem (PV-WFS)
The use of photovoltaic (PV) module as a power source for wirefeeder systems (WFSs) of arc welding machines is one of the promisingdomains in the solar PV applications. This paper provides a new kind of weldingWFS and investigates the PV penetrated power systems. The considered systemconsists of a PV module, a DC-DC buck converter, and PMDC motor. Thepower of the PV-WFS can be widely enhanced by using a Fractional-orderFuzzy PID (FO-Fuzzy-PID) controller based P&O MPPT algorithm. In thiswork, a FO-Fuzzy-PID controller is also proposed for PMDC motor drivenWFS. This will lead consequently to optimize the mechanical motor speed of theWFS. The dynamic response of the PV-WFS relies upon the parameters of theseFO-Fuzzy-PID controllers, which are optimized by using Particle SwarmOptimization (PSO) algorithm. Simulation results found are satisfactory andprove the stability, accuracy and dynamic response of the synthesized optimizedwire feeder regulating system and the proposed intelligent MPPT algorithm. Voir les détails
Mots clés : Solar photovoltaic (PV) module, Wire feeder system (WFS), Arc welding machines, DC-DC buck converter, MPPT control, FO-Fuzzy PID controller, Particle Swarm Optimization (PSO) algorithm
Sensorless Control of DC-DC Converter Using Integral State Feedback Controller and Luenberger Observer
This paper presents a design of linear state feedback control of DC-DC Boost converters, in order to achieve a particular desired behavior. To guarantee a zero steady state error, we introduce an integral action, which will work out this problem by assuring that the steady state error will end up to zero. If it is supposed that both the voltage and current are measured, so much more sensors are needed then and consequently causing a high cost, so that to estimate the voltage and current with a low cost and less complexity it is preferred to introduce a state observer. An observer or estimator is a dynamic system that uses the available information on a real system, according to the inputs and outputs of the real process and estimate the system state. Simulations results demonstrate the robustness and effectiveness of the proposed control scheme. Voir les détails
Mots clés : Boost converter, observer, Static error, Feedback control
State Feedback Control of DC-DC Converter Using LQR Integral Controller and Kalman Filter Observer
In this paper, the linear state feedback control using LQR controller for a DC/DC converter in the case of negative voltages topology is presented in order to achieve a particular desired behavior. To guarantee a zero steady-state error, we introduce an integral action, which will work out this problem by assuring that the steady-state error will end up to zero. For filtering and state estimation with a low cost and less complexity a state observer is obtained based a Kalman Filter observer. Detailed simulation study is presented to demonstrating the robustness and effectiveness of the proposed control scheme. Voir les détails
Mots clés : Linear quadratic regulator, DC/DC Buck-Boost Converter, Kalman filter, Static error
Novel and simplified model representing Current-Output Phase-Shift Full-Bridge DC-DC LCLC Resonant Converter in Arc Welding Application
In this paper, a novel and simplified model representing current-output phase-shift full-bridge DC-DC LCLC resonant converter in arc welding application is thoroughly presented. First, a switched model written in state space representation and featuring a bilinear form is proposed. The latter facilitates the derivation of both the reduced and full order averaged models in continuous conduction mode (ROAM and FOAM). Although the FOAM can be employed in linear or nonlinear control schemes and the derivation of steady state behavior, in this paper the ROAM is considered in designing both voltage mode control and current mode control by using the classical PID and the fractional order PID controllers. Simulation confirms that the switched model, ROAM and FOAM are quite accurate compared to the circuit simulation using SimPowerSystem toolbox of MATLAB/SIMULINK. Results clearly showed that depending on the switching frequency, the proposed topology can be applied either in constant voltage characteristic or dropped characteristic welding machines fulfilling either zero current Switching (ZCS) or zero voltage switching (ZVS). Besides, the fractional order PID controller seems to be more adapted for arc welding application than its traditional version. Voir les détails
Mots clés : LCLC resonant converter, switched model, reduced order averaged model, full order averaged model, arc welding, FOPID, IGWO
A new robust tilt-PID controller based upon an automatic selection of adjustable fractional weights for permanent magnet synchronous motor drive control
This paper focuses on achieving a good trade-off between performance and robustness for a class of uncertainty models including unstructured multiplicative uncertainties. In robust control, the simultaneous improvement of the two secure margins for nominal performances and robust stability using a standard controller structure represents two contradictory objectives and guaranteeing simultaneously of these goals represents therefore a major challenge for most researchers. In this context, a robust tilt-proportional integral derivative (T-PID) controller synthesized with an automatic selection of adjustable fractional weights (AFWs) is discussed in our work. Their parameters are optimized through solving a weighted-mixed sensitivity problem using an optimization tool which is based on the genetic algorithm. This problem is formulated from performance and robustness requirements where a fitness function is accordingly determined. Furthermore, thus its search space is built according to some guidelines for ensuring an automatic selection of adequate AFWs. The proposed constrained optimization problem is initialized by using arbitrary T-PID speed controller as well as through initial fixed integer weights (FIWs) which were chosen previously by the designer. To highlight the proposed control strategy, the synthesized robust T-PID speed controller is applied on the permanent magnet synchronous motor. Their performance and robustness are compared to those provided by an integer-order PID (IO-PID) and two conventional fractional-order PID (FO-PID) controllers. This comparison reveals superiority of the proposed robust T-PID controller over the remaining controllers in terms of robustness with reduced control energy. Voir les détails
Mots clés : Weighted-mixed sensitivity problem, Tilt-proportional integral derivative controller, Fractional-order FO-PID speed controller, Permanent magnet synchronous motor
Microstructural and Mechanical Properties of Welding and Thermal Spraying Coatings on Ductile Cast Iron
The subject of this work is to evaluate the influence and adhesion degree of different coating layers deposited on a ductile cast iron substrate by two different methods, thermal spraying and welding with and without use of an interlayer. Microstructures of different zones and interfaces of coated specimens are investigated using optical microscope and scanning electron microscope SEM. Also, the mechanical behavior was evaluated by tensile test. It is found that when stainless steel thermal spraying coating onto the ductile cast iron substrate, the use of the nickel-based interlayer Ni allowed us to mitigate the disadvantages of cracking at the interface. This is due to the mechanical effect of nickel plasticity. In the case of coating by welding, the use of nickel-based buttering ENi-CI allowed us to reduce the diffusion of graphite to stainless steel, resulting in a reduction in the formation of harder alloy carbides. Finally, the mechanicals tests in particular the tensile test shows that the coating by welding is effective but causes a structural hardening; on the other hand the coating realized by thermal spraying does not really present sufficient adhesion. Voir les détails
Mots clés : Ductile Cast Iron, mechanical properties, microstructure, Thermal Spraying, Welding Coating
On the evolution of microstructure, texture and corrosion behavior of ahot-rolled and annealed AZ31 alloy
The microstructure and texture evolution of an AZ31 alloy were investigated after hot rolling and subsequentannealing using electron backscatter diffraction (EBSD). First, the alloy was hot-rolled at 350 ? C up to low,medium and high strain (20, 50 and 85% of thickness reduction, respectively). The alloy samples where thenannealed at 350 ? C for 2, 10 and 60 min. The effect of strain level and annealing on corrosion behavior inseawater was also evaluated using electrochemical tests. At low strain, the microstructure was characterised bythe absence of twinning, mainly due to the prior thermo-mechanical history of the as-received alloy. However,various modes of twinning were observed at medium strain. At high strain, the dynamic recrystallization processresulted in a microstructure with a typical basal texture. The results demonstrate that twins are responsible forthe deviation of {0002} basal poles from normal towards the transversal direction. Annealing at 350 ? C for up to60 min led to normal grain growth in all the samples. In medium and highly strained samples, the deformationtexture was retained, while the low strain sample underwent noticeable changes due to the absence of dynamicrecrystallization. A synergetic effect of grain refinement and texture weakening was responsible for the alloy’senhanced corrosion resistance.AZ31 alloyCorrosionDynamic recrystallizationStatic recrystallizationRolling Voir les détails
Mots clés : AZ31 alloy, corrosion, Dynamic recrystallization, Static recrystallisation, rolling
Effect of WC-Co cermet positioning and NiCr interlayer on the microstructure and mechanical response of the dissimilar WC-Co / AISI 304 L rotary friction joint
In this work, incompatible properties of WC-Co cermet and AISI 304 steel were combined in the same component using rotary friction welding (RFW) process. The dissimilar joints were performed using a ductile NiCr interlayer with the change in the WC-Co cermet positioning i.e., fixed rotary side and feeding side. Similar microstructure across the weld joints was obtained of the different welding configurations that produced similar behavior in hardness and elastic modulus. A diffusion zone was formed at the weld interface as a result of the mutual inter-diffusion of both cermet (W and Co) and steel elements (Fe, Cr and Ni) that enhanced with the insertion of the interlayer when the cermet was fixed in rotary side. The introduction of the NiCr interlayer was beneficial to relax the residual stresses and improving the shear strength of the WC-Co cermet/AISI 304L steel joints, which is promising technology for drilling tools industries. Voir les détails
Mots clés : Rotary friction welding, WC-Co cermet, mechanical properties, NiCr interlayer, Interface
Influence of isothermal aging in LDX 2101 duplex stainless steel on the microstructure and local properties
In the present work, the interface morphology and the evolution of nitride precipitates in LDX 2101 stainless steel isothermally treated at 750 °C for various aging times were investigated. The microstructure results showed that the Cr2N nitrides precipitated along the δ/γ interface with 200 nm in length and continue to grow to 2 μm after 240 h of aging. However, only Cr2N nitrides were found at the δ/δ interface after long term of aging. Atomic force microscopy (AFM) analysis revealed that Cr2N nitrides andCr23C6 carbides started to precipitate after the first 10 min of aging with a small needle shape of the former and specific triangular morphology of the latter. The evolution of hardness and Young’s modulus of the interfaces, performed with nano-indentation measurements, showed that the δ/γ interface became harder (4.1 ± 0.2 GPa) with increasing aging times, whereas negligible changes in the hardness and elastic modulus were recorded at the δ/δ interface. 3D topographic analysis of the immersed surfaces revealed that the susceptibility of δ phase to preferential dissolution in 3.5% NaCl solution increased with aging time. This behavior was manifested by the important imperfections of δ phase, the high surface roughness (55.7 nm), and the deep corrosion pits (30 nm) along the δ/γ interface and around the Cr2N nitrides. Voir les détails
Mots clés : microstructure, Interface, precipitates, Nano-hardness, Surface degradation