Electro-mechanical system control based on observers

International audienceThe prediction of the gear behavior is becoming major concerns in many industries. For this reason, in this article, an electro-mechanical modeling is developed in order to simulate a gear element driven by an asynchronous motor. The electrical part, which is the induction motor, is simulated by using the Kron's model while the mechanical part, which is the single stage gear element, is accounted for by a torsional model. The mechanical model that simulates the pinion-gear pair is obtained by reducing the degree of freedom of the global spur or helical gear system. The electrical and mechanical state variables are combined in order to obtain a unique differential system that describes the dynamics of the elecro-mechanical system. The global coupled electro-mechanical model can be characterized by a unique set of non-linear state equations. The contribution of this work is to apply the control based on observers in order to supervise the electrical and mechanical behavior of the electro-mechanical system from only its inputs and its measurements outputs (sensors outputs). Some simulations on pinon/motor angular speed, electromagnetic torque, currents, are presented, which illustrate the system evolution (i.e., the electrical and mechanical quantities) and the good performances of the proposed observers

Application of homogeneous observers with variable exponent to a mechatronic system

International audiencePreventive maintenance becomes nowadays more and more essential in many industrial applications. In fact, researchers are always looking for new techniques and analysis tools to monitor the dynamic behavior of their machines. In this context, firstly, we deal with the modeling of an electromechanical system which is accounted for by a hybrid model obtained by assembling the mechanical model of a gear element and the electrical model of an asynchronous motor. Secondly, we use Sliding Mode Observers to supervise the gear dynamic behavior. The observers parameters are suitably chosen to ensure rapid and accurate convergence between the real and the estimated system quantities. Finally, a comparative study between three simulations is presented in order to illustrate the observers performances and the influence of the mechanical dynamics on the electrical ones

INFLUENCE OF UNCERTAINTY IN AERODYNAMIC PERFORMANCE ON THE DYNAMIC RESPONSE OF A TWO STAGE GEAR SYSTEM

In this paper, the nonlinear dynamic response in a wind turbine system is considered and the quantification of uncertainty effects on the variability of this nonlinear response is investigated. Under dynamic conditions, a lumped model with 12 degrees of freedom is proposed taking into account the uncertainty associated to the power coefficient of the input aerodynamic torque. The dynamic response of the two-stage spur gear system is obtained using ODE45 solver of Matlab. The Polynomial Chaos (PC) method is used to introduce the uncertainties on the proposed model. A comparison between the two dynamic responses given by the proposed lumped dynamic model takes into account the uncertainty. It is performed on the existed model without uncertainty. Thus, the efficiency and robustness of the proposed new methodology is evaluated

An electromagnetic-mechanical modeling of an induction motor and rotor shaft coupled to angular approach

Ce papier présente un modèle électromécanique pour simuler le comportement dynamique d'une machine asynchrone / arbre du rotor. Le modèle décrit dans ce travail combine un modèle de réseau de perméances d'un moteur à induction à cage d'écureuil et un modèle dynamique simple de son arbre de rotor. Un échantillonnage angulaire est utilisé pour permettre d'investiguer les variations de vitesse angulaire instantanée et de couple. Le système rotatif est décrit en se référant à la position angulaire de l'arbre. La méthodologie de couplage électromécanique est bien détaillée. En se basant sur un certain nombre de simulations, on montre l'influence des variations de couple provenant de la machine à 'induction sur le comportement dynamique du système mécanique

Electromechanical modeling of motor-gear units : Applications to the detection and monitoring of gear tooth faults

La détection et le diagnostic des défauts d’engrenages ont été traditionnellement basés sur l'analyse des signaux vibratoires et acoustiques. Mais, ces méthodes peuvent être coûteuses suite aux difficultés techniques de mise en œuvre de capteurs sur des pièces en rotation. Dans ces travaux de thèse, une méthode originale de détection de défauts locaux dans des engrenages entraînés par des moteurs électriques est proposée en se basant sur le suivi des courants statoriques. Le système électromécanique est simulé numériquement en combinant un modèle électrique dynamique de moteurs asynchrones (modèle de Kron et modèle des réseaux de perméances) et un modèle mécanique dynamique d’engrenages droits et hélicoïdaux incluant les arbres et les paliers. Certains défauts classiques du moteur (excentricité du rotor) et des défauts d'engrenages (écaillages sur les flancs actifs de dentures) sont considérés et une technique itérative de résolution est présentée qui permet de résoudre le problème électromécanique couplé. De nombreux résultats sont présentés qui illustrent la possibilité et la sensibilité de détection de défauts d’engrenages par mesure de courants électriques sur le moteur. Sur la base de ces simulations, il est conclu que l’analyse de la signature des courants du moteur apparaît comme une méthode suffisamment précise pour détecter et surveiller les défauts locaux d’engrenage comme les écaillages.The fault diagnosis in geared transmissions has been traditionally based on vibration monitoring but the implementation of sensors can be expensive and, in some applications, present technical difficulties. In this thesis, an original way of detecting faulty gears driven by electrical motors is proposed based on the monitoring of the motor currents. The corresponding electromechanical coupled system is numerically simulated by combining i) an electrical dynamic model of asynchronous motors (Kron’s model and permeance network model) and ii) a mechanical dynamic model of spur and helical gears (3D lumped parameter model) including the shafts and bearings. Some classic motor defects (rotor eccentricity) and gear faults (tooth spalls) are considered and an iterative solution technique is presented which makes it possible to solve the coupled electromechanical problem. A number of results are presented, which illustrate the possibility of tooth fault detection by stator current measurements with regard to the position and dimensions of the defect. Based on these simulations, it is concluded that motor current signature analysis can be a viable tool for the detection of localized gear faults such as tooth pitting

Modélisation électro-mécanique de transmissions par engrenages : Applications à la détection et au suivi des avaries

The fault diagnosis in geared transmissions has been traditionally based on vibration monitoring but the implementation of sensors can be expensive and, in some applications, present technical difficulties. In this thesis, an original way of detecting faulty gears driven by electrical motors is proposed based on the monitoring of the motor currents. The corresponding electromechanical coupled system is numerically simulated by combining i) an electrical dynamic model of asynchronous motors (Kron’s model and permeance network model) and ii) a mechanical dynamic model of spur and helical gears (3D lumped parameter model) including the shafts and bearings. Some classic motor defects (rotor eccentricity) and gear faults (tooth spalls) are considered and an iterative solution technique is presented which makes it possible to solve the coupled electromechanical problem. A number of results are presented, which illustrate the possibility of tooth fault detection by stator current measurements with regard to the position and dimensions of the defect. Based on these simulations, it is concluded that motor current signature analysis can be a viable tool for the detection of localized gear faults such as tooth pitting.La détection et le diagnostic des défauts d’engrenages ont été traditionnellement basés sur l'analyse des signaux vibratoires et acoustiques. Mais, ces méthodes peuvent être coûteuses suite aux difficultés techniques de mise en œuvre de capteurs sur des pièces en rotation. Dans ces travaux de thèse, une méthode originale de détection de défauts locaux dans des engrenages entraînés par des moteurs électriques est proposée en se basant sur le suivi des courants statoriques. Le système électromécanique est simulé numériquement en combinant un modèle électrique dynamique de moteurs asynchrones (modèle de Kron et modèle des réseaux de perméances) et un modèle mécanique dynamique d’engrenages droits et hélicoïdaux incluant les arbres et les paliers. Certains défauts classiques du moteur (excentricité du rotor) et des défauts d'engrenages (écaillages sur les flancs actifs de dentures) sont considérés et une technique itérative de résolution est présentée qui permet de résoudre le problème électromécanique couplé. De nombreux résultats sont présentés qui illustrent la possibilité et la sensibilité de détection de défauts d’engrenages par mesure de courants électriques sur le moteur. Sur la base de ces simulations, il est conclu que l’analyse de la signature des courants du moteur apparaît comme une méthode suffisamment précise pour détecter et surveiller les défauts locaux d’engrenage comme les écaillages

An integrated electro-mechanical model of motor-gear units-Applications to tooth fault detection by electric measurements

International audienceFault diagnosis in geared transmissions is traditionally based on vibration monitoring but, in a number of cases, sensor implementation and signal transfer from rotary to stationary parts can cause problems. This paper presents an original integrated electro-mechanical model aimed at testing the possibility and the interest of tooth fault detection based on electric measurements on the motor stator. The motor is simulated using Kron's transformation while the mechanical transmission is accounted for by a lumped parameter model. Tooth defects are assimilated to distributions of initial separations between the mating flanks whose positions and shapes are controlled. A unique non-linear parametrically excited differential system is obtained, which provides direct access to both the electrical and mechanical variables. A number of results are presented, which illustrate the possibility of tooth fault detection by stator current measurements with regard to the position and dimensions of the defect

MODAL ANALYSIS OF GEARBOX TRANSMISSION SYSTEM IN BUCKET WHEEL EXCAVATOR

Planetary gears are widely used in modern machines as ones of the most effective forms of power transmission. In this paper, a special configuration of a gearbox composed of one stage spiral bevel gear and a two stage helical planetary gear used in a bucket wheel excavator gearbox is presented to investigate its modal properties. A lumped-parameter model is formulated to obtain equations of motion and the eigenvalue problem is solved. The modes are presented in low-frequency and high-frequency bands. Distributions of modal kinetic and strain energies are studied