Study On PMLSM And Magnetic Suspension Mechanism For Machine Tools

With the development of modern advanced numerical control (NC) machines, the performance of the linear servo feeding system is more and more important and the research of direct drive of permanent magnet linear servo motor (PMLSM) is meaningful. Based on Finite element electromagnetic field theory, the reason of thrust ripple of large thrust PMLSM used in NC machines is analyzed and the electromagnetic field and thrust ripple of PMLSM is calculated. The electromagnetic design and mechanical design is based on calculation. Finite element analysis to electromagnetic field by ANSYS is used to calculate magnetic field and force to avoid inaccuracy.The end and cogging affect and normal force are the main reasons for thrust ripple of PMLSM, the end and cogging affect is serious for large thrust PMSLM, the thrust ripple is serious too. For reducing the thrust ripple of PMLSM, the paper uses the design method of permeance modulating, the primary of motor uses open slot, both cogging permance and ending permance are modulated, causing the synthesized wave proportionally distributing in odd numbers of permanent magnet pole. The method of permeance modulating is applied in the design of permanent magnet linear servo motor, and conflating the theory of fraction-slot, which can reduce the thrust ripple caused by the ending effect of PMLSM effectively.In addition, considering of the request of production process of PMLSM, according to production characteristics of large thrust PMLSM, mechanical design of motor is designed. The winding of primary motor uses single tooth and concentrated molding coils, having short distance and distributive effect, also having the characteristic which is well craft, short ending of windings, highly density of thrust.In this thesis, the operating principle and system composition are introduced. Single-magnet suspension mathematic model is built according to the analysis on electromagnetic suspension force. Linearity processing near the balance point is needed because of system's nonlinear and parameter uncertainty so as to get state law and transfer function of system. PDF controller of magnetic suspension feed system is designed and MATLAB is used to emulate how the controller work.