Research On The Effect Of Electromagnetic Force Harmonics Of Permanent Magnet Synchronous Motorized Spindle On The Torque Ripple

With the development of numerical control cutting technology, research on numericalcontrol machine tool gradually becomes to be concerned by more and more scholars. Becauseof its small volume and high efficiency, permanent magnet synchronous motorizedspindle(PMSMS), key component of numerical control, is very welcomed by scholars. But themachining accuracy can be seriously reduced by torque ripple in operation of the PMSMS.Therefore, the torque ripple of the PMSMS is researched by this article.The electromagnetic force will be produced in the electromagnetic field of the PMSMS,which is on the set, the rotor structure of motorized spindle. The electromagnetic force can bedecomposed into radial electromagnetic force and tangential electromagnetic force, and thetorque is the product of tangential electromagnetic force and the radius. But due to the factorssuch as harmonic current and stator slot interact with permanent magnet, torque ripple can beproduced. The vibration can be effectively weakened by reducing the torque ripple of PMSMS,especially the machining accuracy of numerical control machine tools can be improved.The torque ripple problem of PMSMS which is the key component of numericalcontrol machine is analyzed and researched. The variation situation of the air gap magneticfield between no load and on load is analyzed and calculated by ANSYS finite elementsoftware. The distribution of tangential magnetic flux density, radial magnetic flux density,tangential force density and radial force density varying with position in air gap in the twosituations are extracted. Air gap field distribution regulation of PMSMS rotor in a cycle isanalyzed. The distribution of tangential magnetic flux density, radial magnetic flux density,tangential electromagnetic force density and radial electromagnetic force density changedwith time are obtained. Instantaneous torque that is changed with time is obtained bynumerical integration. Variation regulation of PMSMS torque ripple is found.One of influence factors on the machining accuracy of numerical control machine tool istorque ripple of the PMSMS. Three kinds of effective method of weakening the torque rippleare studied by design parameters of PMSMS changed and finite element simulation analysissoftware. The first is that reasonably permanent magnet shape is obtained for reducing torqueripple by changing permanent magnet shape for4pole48slot PMSMS. The second is that electromagnetic fields of different pole-arc coefficients are researched, the influence on torqueripple of PMSMS is discussed. It is found that torque ripple has two lower points with therange of the designed pole-arc coefficients. So the ideal pole-arc coefficient is obtained andtorque ripple is effectively reduced. The third method is based on the analysis ofelectromagnetic of many kinds of air-gap lengths of PSMSM, the influence rule of torqueripple is obtained. The research and analysis show that with the increase of air gap length, thetorque ripple values will quickly reduce, and then slowly down, so the best air-gap length isdetermined. The gist is provided for low torque ripple of PMSMS.