High performance motor and magnet assembly therefor

Abstract

A magnet assembly includes a back iron and an array of magnets. The back iron is in the form of a plate having opposed surfaces. The magnets are arranged along one of the surfaces, with the other surface being dimensioned and configured according to the magnetic field distribution associated with the magnets. The back iron geometry provides for reduced mass, reduced leakage flux, and high flux densities to improve performance of a linear motor that employs such a magnet assembly. Additionally, the back iron can be a magnetically conductive annular ring, such as is employed in a rotary motor. Moreover, the magnets can be arranged in a manner that generates a Halbach array to increase force output in a desired direction while canceling stray magnetic fields in other directions. Similar reduced-mass designs can be employed in conjunction with a back iron of a fixed cross-section and magnets of variable thicknesses, variable lengths, and/or variable widths. In a case where the arrangement is employed in a platen and forcer system, plates on both the platen and forcer may be scalloped to reduce mass.