Development of High-Force-Density Iron-Core Linear Synchronous Motor

The demand for small-sized and high-acceleration linear motors for industrial machines such as semiconductor production equipment and LCD equipment is rapidly increasing in order to maintain the small size of these equipment and to increase productivity. To satisfy the demand, high-force-density (i.e., force per volume) linear motors are required. This paper discusses the development of a high-force-density iron-core linear synchronous motor that consists of a Halbach magnet array with soft magnetic material and a grain-oriented silicon steel sheet core; the motor has a shape-optimized design. The motor constant square density of the new linear motor reaches 10N2/W/cm3, while that of the highest force linear motor available at present is 5N2/W/cm3. In other words, the new motor can deliver a force of 900N per 1000cm3. In this paper, details of the design, especially the structure and performance of the new motor are presented, and the design is validated on the basis of measurements of a prototype motor.