Analysis and implementation of a tubular motor with Halbach magnet array

In the machine tool industry, direct-drive linear motor technology is of increasing interest as a means to achieve high acceleration, and to increase reliability. This paper discusses the analysis, design and operating characteristics of a novel ironless tubular linear motor that incorporates a magnet array with a magnetization pattern inspired by the Halbash array used in synchrotron light sources. The advantages of such a motor are that it is free of cogging, has efficient cooling, and has low inductance. The authors derive magnetic field solutions, force relations and commutation laws for the motor. Test results such as thrust measurements and step response are also given to confirm the analysis