Design And Analysis Of Permanent Magnet Linear Synchronous Motor Used In Machine Tools

With the development of machine tools oriented to high precision, high speed, intelligence and environmental protection, the driving method of machine tool feed system is demanded higher. The traditional driving method using rotary motor ball screw structure is limited by screw, so that its relevant servo performance is not easy to improve significantly. Compared to the traditional driving method, linear motor direct driving method, which eliminates the influence of reverseclearance, slow response, great loss and lack of rigidity, dramatically improves the performance of machine tools. The thesis focuses on the design and analysis of the permanent magnet linear synchronous motor (PMLSM) that is part of high speed and high precision five-axis gantry machining center. Main contents of this thesis are configured as below.(1) An overview on the quo of development of linear motor used in machine tools is presented. Current optimization techniques taken to minimize the detent force of linear motor are summarized as well.(2) Referring to the design method of rotary motor, the formulas for the electromagnetic design of linear motor are derived. On this basis, initial electromagnetic parameters including main dimensions, air gap size, size and no-load operation points of permanent magnet, groove type and configuration of windings are determined in accordance with the given technical requirements. For the purpose of simplifying design process and improving design efficiency, the thesis develops an electromagnetic design software platform based on Visual C++.(3) The air-gap magnetic field of the PMSLM is analyzed. Regarding the permanent magnet as an independent field source on the border of analysis area, the analytical solution of the air-gap magnetic flux density is obtained using the method of Fourier decomposition.(4) The principle of thrust fluctuations of the PMSLM is studied deeply. And then its end force is reduced by optimizing the primary core length, edge teeth width and cutting angle of edge teeth. In order to minimize the cogging force of the motor, the numbers of poles with slots, width of notch and air-gap length are optimized. According to those preliminary designs, electromagnetic field simulation models for the PMSLM are established by using Ansys Maxwell, a kind of finite element analysis software.(5) According to the optimization, an experimental prototype of the PMSLM with 28 poles and 24 slots is produced and the corresponding test platform is also built. Experiment results demonstrate that the correctness and effectiveness of the proposed design method.