Design Of Linear Servo Motor And Analysis Of Its Normal Force

In machine tool servo systems, direct drive of linear motor can eliminate the middle part of the transformation, besides, it has some characteristies such as high precision, high speed and long trip. Normal force is one of the key factors which cause thrust tipple, factors which affect normal force and measures which can reduce the ripple of normal force were researched in this thesis.Firstly, based on the characteristics of permanent motor and linear motor, the principle of electromagnetic design of permagnet magnetic linear synchronous motor (PMLSM) was summarized, the electromagnetic design scheme of the motor was put forward. Detent force is the major factor which causes thrust ripple, the electromagnetic design scheme of the motor should reduce this kind of thrust ripple effectively, permeance modulation and the fractional-slot theory were applied to the design of PMLSM.Reasons which cause normal force were analysed. Normal force consists that normal force between permanent magnet and iron core, normal force between permanent magnet and travelling wave magnetic field, normal force between permanent magnet and machine tool.Properties, average value and ripple amplitude of normal force were researched with different power angles, currents and air gaps. Normal force between permanent magnet and travelling wave magnetic field may be attractive, repulsive or zero with different power angles. Influence of current to normal force has contact with power angles, when current is increasing, normal force may become bigger or smaller with different power angles.Different electromagnetic design schemes were researced to reduce normal force or the ripple of normal force. Permeance modulation were applied to the design of PMLSM, adjusted the phase angle of the two sides of the primary and two units motor were researched to reduce the ripple of normal force through analysed theories firstly, then the theories were certified correctly after calculated though Finite Element Method. These schemes which were designed to reduce the ripple of normal force were not researched alone, the thrust ripple caused by detent force were researched at the same time in order to choose the better electromagnetic design scheme.