Study On The Generation Mechanism Of Electromagnetic Force And Vibration Characteristics Of Permanent Magnet Synchronous Electric Spindle

The Permanent Magnet Synchronous Electric Spindle(PMSES) is the most significant part of high speed machining technology. The electromagnetic vibration caused by the radial electromagnetic force is the main factor to influence of accuracy the high speed machining. In this paper, the mechanism of the electromagnetic force of the PMSES is analyzed theoretically. The results show that the interaction of fundamental wave magnetic field and a series of harmonic magnetic field in air gap produces the radial and tangential electromagnetic force. The electromagnetic force and vibration characteristics of the PMSES are analyzed by finite element method. The main contents include electromagnetic field analysis, modal analysis and structural parameter analysis.The two-dimensional electromagnetic field of PMSES is modeled and solved by finite element analysis software. The magnetic flux density, magnetic field distribution in the air gap is obtained. Then, the radial and tangential electromagnetic force on the surface of stator teeth of PMSES is calculated by the Maxwell stress tensor method. The harmonic analysis and spectrum analysis of the results are conducted with calculation software.Using Ansys Workbench finite element software, a three-dimensional model of the PMSES is established. Modal simulation of stator, end cover and the whole machine of PMSES is carried out. The natural frequencies and mode shapes are obtained. Modal frequencies comparing with the frequency components of the radial electromagnetic force wave of PMSES, the result shows that resonance phenomenon of PMSES is not existed.Different structure parameters of PMSES are contrasted and analyzed. The influence of structure parameters including slot width, the height of the stator slot shoulder and pole arc coefficient on the air gap flux density and electromagnetic force is also analyzed. In order to improve the electromagnetic torque and reduce the vibration and noise of the PMSES, a novel wedge air gap structure is introduced. By using finite element software, two kinds of models of PMSES which have the uniform and the wedge air-gap structure are simulated. The electromagnetic torque and the radial force of the two kinds of models are compared. The conclusion is that the PMSES with the wedge air gap structure can increase the electromagnetic torque and decrease radial forces. Furthermore, the vibration and noise of PMSES are reduced.