| High-speed CNC machine tools are one of the technical foundations and development directions of the equipment manufacturing industry.The level of technology and the number of them reflect the level of manufacturing in a country.As the core component of high-speed CNC machine tools,permanent magnet synchronous electric spindle has the following advantages compared with other types of electric spindle: high power density and power factor,larger power-to-volume ratio,smaller moment of inertia and wider speed range.Start and stop response accuracy is higher.Although the permanent magnet synchronous electric spindle has many advantages,there are still some problems affecting its dynamic performance worthy of research and discussion,one of which is the unbalanced magnetic pulling force.The cogging torque is generated by the structure of the electric spindle,which causes the electric spindle to vibrate,which causes the air gap to be eccentric,resulting in unbalanced magnetic pulling force and affecting the dynamic performance of the electric spindle.This paper is supported by the National Natural Science Foundation of China "Hybrid drive electric spindle drive performance and intelligent control research"（project number 51405209）,Horizontal research project "Development of high-speed high-precision permanent magnet synchronous electric spindle"（project number KYH17002）,Jiangsu Province University Self-study Major Project（Project No.19KJA510001）,and the Jiangsu Provincial Graduate Innovation Project（project number SJCX181060）,the main body structure optimization simulation analysis and research on the permanent magnet synchronous electric spindle were carried out,mainly doing the following work:In order to improve the dynamic performance of permanent magnet synchronous electric spindle,the mechanism of unbalanced magnetic pulling force of permanent magnet synchronous electric spindle is studied.Firstly,the unbalanced magnetic pull load model is established according to the electromagnetic theory.Then the air gap magnetic permeability is expanded in the form of Fourier series.Then the analytical expression of unbalanced magnetic pull force is obtained by Maxwell stress integral on the stator surface.Finally,it is proposed to weaken.The cogging torque suppresses the unbalanced magnetic pulling force and improves the dynamic performance of the electric spindle.In order to achieve the purpose of suppressing unbalanced magnetic pull force and improving the dynamic performance of the electric spindle,the mechanism of cogging torque of permanent magnet synchronous electric spindle is analyzed firstly,and several analysis methods of cogging torque are expounded.Secondly,the analytical expression of cogging torque based on energy method is given.Then the expression of cogging torque is analyzed by Fourier series method.Finally,three methods of cogging torque reduction of permanent magnet synchronous electric spindle are briefly described.Based on the analysis of the relationship between cogging torque and pole arc coefficient,a method for optimizing the combination of pole arc coefficient and pole eccentricity is proposed.Taking the 4-pole 36-slot surface-mount permanent magnet synchronous electric spindle as an example,the finite element model of the electric spindle is established,and the polar arc coefficient and the magnetic pole eccentricity are solved parametrically.Finally,the correctness and effectiveness of the polar arc coefficient and magnetic pole eccentric combination optimization method are verified by analyzing the simulation results.Based on the analysis of the relationship between cogging torque and slot width,a method for slot width optimization based on different slot types is proposed.Then according to the structural parameters of the 4-pole 36-slot surface-mount permanent magnet synchronous electric spindle,the finite element model is established and the slot width is solved parametrically.Finally,the simulation results are compared and proved that the optimization method has a significant effect on weakening the cogging torque,suppressing the unbalanced magnetic pull force and improving the dynamic performance of the electric spindle. |
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