Design and Analysis of a High Thrust Linear Voice Coil Motor Using for the Stiffness Test of Linear Motor Servo System

Abstract

Linear voice coil motors (VCMs) are widely used in some high precision or high dynamic applications, such as lithography, digital cameras, and microscopes. In this article, a high thrust linear VCM is analyzed and designed, which is used for the position loop stiffness test of linear motor servo system. To guarantee the structural strength of coil frame and provide space for the cooling channels, the two layers’ coil arrangement is adopted. Based on 2-D finite element method (FEM), the thrust and thrust ripple performance of the motor are analyzed. Moreover, a reasonable cooling structure integrated with the coil frame is designed to further improve the thrust density. Finally, a linear VCM prototype with a thrust rating of 1000 N is manufactured and tested. The static thrust test results show that the thrust varies linearly with the coil current. The motor can provide a nearly constant thrust and thrust ripple within ±2 mm displacement is less than 1%, which agrees well with finite element simulation. In addition, the temperature test is also achieved. Compared with natural cooling condition, the thermal equilibrium can be achieved among the coil, coil frame and cooling water with the water-cooling condition, when the current density is 15.3 A/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Furthermore, a good overall cooling effect and low surface temperature rise can be realized when two heat shield cover plates are fixed onto both sides of the primary.