DESIGN AND ANALYSTS FRAMEWORK FOR LINEAR PERMANENT-MAGNET MACHINES

This paper presents a design and analysis framework for the general cl ass of permanent-magnet electric machines. In our analysis, surface-mo unted linear motors consisting of permanent magnets and iron-less curr ent carrying coils are treated in a uniform way via the magnetic vecto r potential. This analysis is developed to design novel linear magneti c levitators for driving precision motion control stages such as those used in wafer steppers, For one such motor structure we give analytic al formulae for its magnetic field, force, flux linkage, inductance of the winding, and back electromotive force. We provide experimental re sults with a six-degree-of-freedom magnetic levitator. These results a re in good agreement with analytical estimations. The levitator uses a permanent-magnet Halbach array in order to improve its power efficien cy. By analogy, there also exists an electromagnetic dual of the Halba ch array. One such dual utilizes a triangular winding pattern in order to achieve a primarily single-sided magnetic field.