Research On Fault Tolerant Operation Technology Of Multi-Winding Control Loop For Active Magnetic Bearings

The active magnetic bearing is a mechatronics complex control system.The rotor is stably suspended in the desired position by the controllable electromagnetic force.There are a series of advantages that traditional bearings can't match,such as no friction loss,no heat,no lubrication and long working life.Therefore,active magnetic bearings are used in more and more practical industrial equipment.How to further improve the safety and reliability of operation is the key to the wider application of magnetic bearings.In this paper,the redundant structure and fault-tolerant control of radial magnetic bearings are studied in detail.First of all,this paper outlines the development of magnetic suspension bearings,the failure modes of magnetic bearings and the research status of redundant fault-tolerant control at home and abroad.The basic composition and mathematical model of the magnetic bearing system are introduced,and the working principle of the magnetic bearing is expounded.The redundant structure of the displacement sensor and power amplifier in the magnetic bearing system is analyzed in detail.The reliability of the redundant system is analyzed and compared by simulation,and the effectiveness of the redundant structure is verified.Secondly,based on the theory of bias current linearization,the radial magnetic bearing with eight magnetic pole coupling structure and weak coupling structure is analyzed.According to the model and equivalent magnetic circuit under different structures,the decoupling and linearization of the electromagnetic force are realized.The semi-physical simulation platform of magnetic bearing based on RTW is built.The establishment of simulation model and the application of dSPACE are introduced in detail,and the stable suspension of the rotor in two degrees of freedom is realized,which verifies the good performance of the experimental platform.Finally,fault-tolerant control method of multi-winding loop based on minimum power consumption is proposed.The process of solving the current distribution matrix under minimum power consumption is introduced in detail.The electromagnetic force of fault winding is distributed to other normal windings and all winding loops consume the least energy.In addition,the fault modes of magnetic bearings are summarized and enumerated,and all the basic fault types that can achieve fault-tolerant control are listed.When one or more winding loops fail,only the current distribution matrix corresponding to the basic fault type needs to be solved,and the current distribution matrix of the same fault type can be obtained according to the coordinate transformation matrix and the winding remapping matrix,so fault tolerant control of different fault combinations can be realized.The design and implementation process of the method are described in detail.The Simulink simulation is used to compare the energy consumption of the differential control and the fault-tolerant control method,and the effectiveness of the fault-tolerant method is verified by experiments.The results show that the method can effectively reduce the winding current consumption,simplify the fault-tolerant process and improve the reliability of the system.