Design and analysis framework for linear permanent magnet machines

This paper presents a design and analysis framework for the general class of permanent magnet electric machines. In the analysis, two-dimensional linear or planar motors consisting of permanent magnets and current-carrying coils are treated in a uniform way via the magnetic vector potential. This analysis is developed in order to design novel linear motors for driving precision motion control stages such as those used in wafer steppers. For one such motor structure the authors give analytical formulae for its magnetic field, flux linkage, inductance of the winding, and back electromotive force (EMF). The motor uses a permanent magnet Halbach array in order to improve its power efficiency. By analogy, there also exists an electromagnetic dual of the Halbach array. One such dual utilizes a triangular winding pattern in order to achieve a primarily single-sided magnetic field. The authors also present an efficient magnet matrix for planar surface motors