The Research On On-line Self-diagnosis Control System Of Magnetic Suspension Bearing

The magnetic suspension bearing has become ideal support for high-speed precision rotors due to its outstanding advantages of no mechanical contact,no wear,no lubrication and high speed.Therefore,it has wide application prospects in machine tool industry,aerospace,vacuum technology and energy storage flywheel.Reliability is the key problem to be solved in the popularization and application of magnetic bearing.When some parts of the magnetic bearing system fail,it will affect the normal suspension of the high-speed rotor,even lead to its fall,resulting in serious consequences.Fault-tolerant control by designing redundant structure for support reconstruction is an effective method to improve the reliability of magnetic levitation support.However,the precondition of the above idea is to diagnose all kinds of faults effectively.Only by detecting faults quickly and accurately and expressing fault characteristics,can the effectiveness of fault-tolerant control strategy be guaranteed.For this reason,this paper carried out the research on the fault diagnosis method of magnetic bearing,and designed an on-line self-diagnosis control system of magnetic bearing,and carried out relevant experiments to verify the validity of this research.The main contents of this paper include:(1)Starting from various fault forms of magnetic bearing system,the mechanism of the corresponding fault was analyzed,the main fault forms were classified,and the corresponding methods to avoid the occurrence of the fault were put forward.(2)Aiming at the local short-circuit fault of electromagnetic coil,the theoretical analysis and proof of its fault diagnosis method were carried out,and a fault diagnosis method based on the current variation characteristics of power amplifier in the modulation period was proposed.The validity of the method was verified by the simulation of Matlab/Simulink model.(3)An on-line self-diagnostic control system of magnetic bearing was developed.According to the main fault types in(1),the corresponding on-line fault diagnosis strategy and self-diagnostic control algorithm of magnetic bearing were designed.(4)The test platform of the magnetic bearing-rotor system was built,and the related experiments were carried out for different fault types.The experimental results show that the fault diagnosis strategies studied in this paper can detect the corresponding faults in a very short period of time.The innovation of this paper lies in: at present,it is difficult to distinguish the local short circuit fault of electromagnetic coil effectively and its fault manifestation is difficult to be observed intuitively.In this paper,a fault diagnosis method based on current variation characteristics in modulation period was proposed,which grasps the essential characteristics of the influence of local short circuit of electromagnetic coil on its current change rate,and the effectiveness of the proposed method was verified by theory,simulation and experiment.As a key component of reliability design for magnetic bearing,the research in this paper is an effective basis for further fault-tolerant control and has good theoretical and practical value.