The Study On Stiffness Of Bearingless Slice Motor With Permanent Magnet And Single Set Of Winding

With the development of science and technology,man-made devices are implanted into human body to replace human organs to achieve physiological functions and gradually become an important medical treatment,one typical of which is the blood circulation aids.The main component of the blood circulation auxiliary equipment,that is,the artificial blood pump is implanted into the human body in a surgical manner and is directly connected with the arteriovenous blood vessels of the heart.The blood enters the blood pump chamber and is driven by the blood pump to return to the human blood circulation system so as to achieve the therapeutic effect of the auxiliary blood circulation.Blood circulation aids are involved in many disciplines such as mechanics,electronics,fluids,biomedicine,etc.There are many technical difficulties and bottlenecks in theoretical research and practical engineering applications.This article mainly focuses on a typical driving method applied to blood pump,that is,to study the stiffness characteristics of the bearingless motor drive.Bearingless motors have a variety of forms.In this paper,single-winding bearingless permanent magnet sheet motor is taken as the research object,and the influence mechanism of the motor’s structure,size and material properties on the stiffness characteristics of the motor is studied.Firstly,this paper establishes the analytical model of the influencing mechanism.Then the finite element analysis method is used to compare and analyze the accuracy of the analytical model.According to the results of the finite element analysis,the analytical model is revised.Finally,the stiffness characteristics of the prototype are measured by a self-designed measurement platform.The revised analytical model was verified.Based on the analysis idea of the equivalent magnetic circuit network,this paper analyzes the internal magnetic field of the research object,combines the Maxwell stress tensor and the principle of virtual work,and establishes the axial passive stiffness and radial passive stiffness of a single-winding bearingless permanent magnet sheet motor.The analytical model of radial force-current characteristics and torque-current characteristics.Using finite element software ANSYS Maxwell,finite element analysis of the motor was performed to obtain the numerical results of axial passive stiffness,radial passive stiffness,radial force-current characteristics,and torque-current characteristics.By comparing the numerical calculation results with the analytical calculation results,the accuracy of the established analytical model was analyzed and the analytical model built was revised.According to the measurement requirements of the stiffness characteristics of the motor,a test bench for measuring the stiffness of the motor was designed.The axial passive stiffness and radial passive stiffness of the machined prototype were measured.The modified passive axial stiffness and radialpassive stiffness were verified.The modified analytical model can offer insights for optimization design and control of bearingless permanent magnet slice model with single set of concentrated winding.