Research On Active Fault Tolerant Control And Experiment Of The Varistructured Permanent Magnet Linear Synchronous Motor

Electromagnetic Aircraft Launch System (EMALS) is used for take-offassistance of the carrier aircraft; it is becoming a popular research subject in thecarrier-related area. Control reliability of the linear motor is a key issue for theEMALS project. According to the literatures found, nearly seventy percent of theliteratures in this area are somehow related to the control reliability of the linearmotor problem. However, in the literature, all the proposed solutions are based on thecentralized or segmented linear motor. These kinds of motors are low reliable interms of their lack of system redundancy, once a segment of the motor collapses, thewhole launch system fails.For the unreliable problem of the research in the literature, we propose avaristructured permanent magnet linear synchronous motor (PMLSM) withindependent winding of each stator tooth, expecting to solve the problem ofefficiency optimization、 dynamic thrust control quality, and the motor controlreliability; And propose an active fault tolerant control methodology for thevaristructured PMLSM used in EMALS; study the key technologies for the reliabilityrelated issue the PMLSM. And experiments were carried out to prove the proposedmethod.The centralized or segmented linear motors are low reliable; and in the aspect ofthe efficiency, motors with constant structural parameters are unsuitable for theunidirectional working condition. First of all, this paper studies the structurevariation of the proposed varistructured PMLSM, and analyzes its attribute. In thispart of the job, the structural parameters variation of the motor is analyzed. Theinfluences of the structural parameters in different speed section on the air gap fluxdensity, and the influences of the structural parameters variation on the thrustmagnitude and thrust ripple, are studied based on the finite element analysis. Thecontrolled objects of every coil are different due to the variation of the motorstructure, so independent control of each coil is needed. For this requirement, thewound method of the PMLSM and the influence of the variable structure on coilattribute are studied. Mathematical model of the PMLSM considering coil attributedifference is built. These studies and their results provide reference to theautonomous decentralized control of the proposed PMLSM.For the control methodology, this paper proposes the autonomous decentralizedcontrol strategy for the fault tolerant control. The vector control of the PMLSM bymultiple autonomous atoms is proposed, based on the explicit coordination of the atoms. In addition, thrust control model of the motor and a back-electromotive forcebased control methodology are proposed, according to the nonlinear variation of thestructural parameters. In order to improve the system response frequency, strategiesbased on state observer for the velocity and position control are proposed, andsimulations and experiments are carried out.For active fault tolerant control of the varistructured PMLSM, this paperproposes a corresponding fault detection and diagnosis methodology. In this part ofthe job, the faults of the autonomous decentralized atoms are categorized, accordingto the special feature of the PMLSM control. And fault diagnosis method of themajor faults of the atoms and basic motor unit output decrement are studied. Inaddition, a digital filter for fault signal is designed, for the improvement of the faultdetection accuracy.For the most important part of the paper, an active fault tolerant control strategyfor the PMLSM is proposed based on the control law reconfiguration. And based onthe fault detection and diagnosis result of the motor and its autonomous controlatoms, we analyze different fault features of the PMLSM. On the basis of the faultfeature analysis, we propose the mathematical model of the control lawreconfiguration, and study the stability of the reconfigured system.In the end, we build a test bench for the fault tolerant control of the PMLSM,and describe the algorithm of the system. In the fault tolerant control of theexperiment of the PMLSM, the results of the faults diagnosis and the current controllaw reconfiguration are shown. The comparison experiments of the acceleration andvelocity of the PMLSM’s secondary are carried out. The experiment results prove theproposed fault tolerant control methodology.