Développement d'une méthode commune de diagnostic et pronostic basée sur un cadre formel de modélisation générique. Application à un module électro-hydrostatique aéronautique

National audienceThe aviation industry is a changing market where demands on the equipment are high, and competition is fierce among manufacturers. Therefore cost reduction, quality, reliability, operational availability and dependability become the cornestone of this industry. One of the levers that can support manufacturers to make their products more attractive for airlines is the optimization of maintenance. A way to achieve this is health-monitoring.In order to provide the integration of diagnosis and prognosis in one same method, this thesis proposes a formal approach of health-monitoring. One of the aims is to help in the optimization of maintenance operation. The method is based on a generic modeling framework. This framework represents the behavior of any complex system at a given time, and the evolution of its health over time depending on the stress it undergoes. The model summarizes the information needed for both diagnosis and prognosis. The diagnosis provides a good knowledge of all the damages and faults present in the components of the system, and any associated losses of performance and failures. From the result of diagnosis, the prognosis allows the prediction of the future health state of the system and the deduction of the nature and the times of occurrence of future possible failures. Performance metrics in the diagnosis and prognosis, as well as uncertainties related to prognosis, are discussed and integrated in the formal approach.The chosen application is the motor-pump of an electro-hydrostatic actuator, a technology pushed by Messier-Bugatti-Dowty to meet the needs of future all-electric aircrafts. The process of monitoring the health state focuses on two critical elements : a synchronous permanent magnet machine and a hydraulic pump The application shows the feasibility of health-monitoring, and highlights the problems that should be treated in the future to obtain, in particular, realistic aging laws.L’industrie aéronautique est un marché en perpétuelle évolution où les exigences sut les équipements sont hautes, et où la concurrence est rude entre les équipementiers. Il est donc primordial de tenir les enjeux de réduction de coût et de délai, de qualité, de fiabilité, de disponibilité opérationnelle et de sûreté de fonctionnement. L’un des leviers sur lesquels peuvent appuyer les équipementiers pour rendre leurs produits plus attractifs aux yeux des compagnies aériennes est l’optimisation des opérations de maintenance. Dans cette optique, une voie de plus en plus explorée par les industriels est le suivi de l’état de santé.Dans l’objectif de proposer l’intégration du diagnostic et du pronostic dans une même méthode, ces travaux proposent une approche formelle de suivi de l’état de santé des équipements, dont une finalité permettra d’optimiser l’organisation des opérations de maintenance. La méthode est basée sur un cadre de modélisation générique. Ce cadre permet de représenter le comportement de tout système complexe à un instant donné, ainsi que l’évolution de son état de santé dans le temps en fonction du stress qu’il subit. Le modèle ainsi construit synthétise les informations nécessaires à la fois au diagnostic et au pronostic. Le diagnostic permet de connaître l’ensemble des endommagements et fautes présents dans les différents composants du système, et les éventuelles pertes de performance et défaillances associées. Le pronostic permet, à partir du résultat de diagnostic, de prédire l’état de santé futur du système et d’en déduire la nature et les instants d’apparition des futures défaillances. Les métriques de performance du diagnostic et du pronostic, ainsi que les incertitudes liées au pronostic, sont discutées et intégrées à l’approche formelle.L’application choisie pour ce travail de recherche est le groupe moto-pompe d’actionneurs électro-hydrostatiques, une technologie poussée par Messier-Bugatti-Dowty pour répondre aux besoins des futurs avions tout électriques. La démarche de suivi de l’état de santé porte sur deux éléments critiques : la machine synchrone à aimants permanents et la pompe hydraulique. L’application montre la faisabilité du suive de l’état de santé, et met en évidence des verrous qu’il convient de traiter de manière pluridisciplinaire pour obtenir, en particulier, des lois de vieillissement réalistes

A generic ageing model for prognosis - Application to Permanent Magnet Synchronous Machines

International audienceIn the context of more electrical aircrafts, Permanent Magnet Synchronous Machines are used in a more and more aggressive environment. It becomes necessary to supervise their health state and to predict their future evolution and remaining useful life in order to anticipate any requested maintenance operation. Model-based prognosis is a solution to this issue. A generic modeling framework is proposed in this paper in order to implement such a prognosis method which relies on knowledge about the system ageing. A review of existing ageing laws is presented, and motivates the choice to developp an ageing model that could incorporates every kind of ageing laws. A generic ageing model is then defined, that allows representing the ageing of any equipment and the impact of this ageing on its environment. It includes the possible retroaction of the system health state to itself through stress increase in case of damage. The proposed ageing model is then illustrated with Permanent Magnet Synchronous Machines. A fictive but realistic scenario of stator ageing is built. It comprises apparition and progression of an inter-turns short-circuit and its impact on stator temperature, which value has an impact on the ageing speed. A prognosis method based on the generic ageing model is proposed, and applied successfully to this scenario

Synchronous machine faults detection and isolation for electro-mechanical actuators in aeronautics

International audienceThe reported work is the design of a Fault Detection and Isolation system for an innovative 12-slots 10-poles synchronous machine that becomes more and more popular in aeronautics. Two main faults occurring on this machine are identified as inter-turns short-circuit and rotor single pole demagnetization, and characterized. An analytical model of the motor is developped using Matlab Simulink. This model allows simulating nominal and faulty motor behaviour. It is parameterizable and is able to simulate several stages of degradation. Specific indicators are proposed for each fault. They do not require additional material or sensors since they are based on the signals already monitored for the machine control. Inter-turns short-circuit and pole demagnetization are successfully detected and identified

Permanent Magnets Synchronous Machines Fault Detection and Identification

International audienceThe reported work is the design of a Fault Detection system for permanent magnet synchronous machines (PMSM). Two main faults occurring on these machines are identified as inter-turns short-circuits and rotor single pole demagnetization, and characterized. An analytical model of the PMSM is developed and simulated using Matlab Simulink. The model enables simulating nominal and faulty PMSM behavior, with several stages of degradation, and is supported by tests results. Specific indicators are proposed for each fault. They do not require additional material or sensors since they are based on the signals already monitored for the machine control. An application is made on a 9-slots 8-poles synchronous machine being popular in aeronautics

A generic diagnosis and prognosis framework: application to permanent magnets synchronous machines

International audienceIn the context of electrification of aeronautical actuation systems, aircrafts manufacturers intend to more and more supervise the health state of equipment during their service life. The objective is to increase the operational availability of systems, and to organize efficient maintenance management for safety and economic reasons. In this purpose diagnosis and prognosis are performed to determine the current and future health state of mechanical, electrical, and hydraulic equipment. A generic modeling framework is first proposed. It is made of two parts. First a structural and functional model enables representing nominal, faulty, abnormal, or unknown behavior of a complex system. It also describes the functional interaction between its components. Then an ageing model allows representing the system degradation through time thanks to the knowledge available about its ageing, from physical laws or experience. It also shows the effect of damaged components on others, and the propagation of ageing-related performance losses through the system. The evolution of the machine health state in nominal case and during faults initiation and progression is modeled. A health assessment method is then proposed based on this generic modeling framework. It is meant to evaluate the health state of any complex system at any time of its life. This method comprises two modules. The detection and diagnosis module assesses the system current health state. The prognosis module assesses the system future health state and computes the remaining time before failure. Permanent Magnet Synchronous Machines (PMSMs) are used as an illustration. These machines are used in crucial applications including landing gears systems, Messier-Bugatti-Dowty core business. They are subject to critical progressive faults such as short-circuits and rotor demagnetization that are successfully modeled by the proposed framework. The health assessment method is then implemented on healthy and faulty simulated PMSMs and developed algorithms succeed in assessing current and future health state of the machines

Modelling and simulating the pump of an aerospace electro-hydrostatic module for fault detection and identification purposes

ISBN: 978-0-7918-4597-4International audienceThis communication deals with the modelling and simulation of a fixed-displacement axial-piston pump used in aerospace electro-hydrostatic actuators. The pump model is developed in the LMS-AMESim simulation environment to support the development of fault detection and identification features. The model-based fault diagnosis method is introduced first and the modelling needs are addressed. Then, a system-level pump model is proposed with special considerations to model architecture. The different ways to improve the model's realism are reviewed, in particular concerning energy losses (bearing friction, leakages in gaps), barrel force balance, piston back pumping, piston eccentricity and pump loading for tests. Finally, directions of research in system-level modelling of hydraulic effects are suggested

Modelling and simulating the pump of an aerospace electro-hydrostatic module for fault detection and identification purposes

ISBN: 978-0-7918-4597-4International audienceThis communication deals with the modelling and simulation of a fixed-displacement axial-piston pump used in aerospace electro-hydrostatic actuators. The pump model is developed in the LMS-AMESim simulation environment to support the development of fault detection and identification features. The model-based fault diagnosis method is introduced first and the modelling needs are addressed. Then, a system-level pump model is proposed with special considerations to model architecture. The different ways to improve the model's realism are reviewed, in particular concerning energy losses (bearing friction, leakages in gaps), barrel force balance, piston back pumping, piston eccentricity and pump loading for tests. Finally, directions of research in system-level modelling of hydraulic effects are suggested