A new magnetic bearing using Halbach magnet arrays for a magnetic levitation stage

Abstract

Modeling and analysis of a magnetically levitated synchronous permanent magnet planar motor J. Appl. Phys. 111, 07E706 (2012) Magnetic navigation system for the precise helical and translational motions of a microrobot in human blood vessels J. Appl. Phys. 111, 07E702 (2012) Fluidic electrodynamics: Approach to electromagnetic propulsion Phys. Fluids 21, 097103 (2009) Characteristic analysis of electrodynamic suspension device with permanent magnet Halbach array J. Appl. Phys. 105, 07A314 (2009) Electric generator using a triangular diamagnetic levitating rotor system Rev. Sci. Instrum. 80, 024702 (2009) Additional information on Rev. Sci. Instrum.Next-generation lithography requires a high precision stage, which is compatible with a high vacuum condition. A magnetic levitation stage with six degrees-of-freedom is considered state-of-the-art technology for a high vacuum condition. The noncontact characteristic of magnetic levitation enables high precision positioning as well as no particle generation. To position the stage against gravity, z-directional electromagnetic levitation mechanisms are widely used. However, if electromagnetic actuators for levitation are used, heat is inevitably generated, which deforms the structures and degrades accuracy of the stage. Thus, a gravity compensator is required. In this paper, we propose a new magnetic bearing using Halbach magnet arrays for a magnetic levitation stage. The novel Halbach magnetic bearing exerts a force four times larger than a conventional magnetic bearing with the same volume. We also discuss the complementary characteristics of the two magnetic bearings. By modifying the height of the center magnet in a Halbach magnetic bearing, a performance compromise between levitating force density and force uniformity is obtained. The Halbach linear active magnetic bearing can be a good solution for magnetic levitation stages because of its large and uniform levitation force.

Electromagnetic force compensation weighing cell with magnetic springs and air bearings

“…Gravity compensation from the magnetic spring reduces the actuator size and nominal current consumption, which can induce a weighing error by thermal expansion. The magnetic spring is composed of a single cubeshaped magnet and Halbach magnet arrays comprising six cuboid magnets surrounding the single magnet [20]. The Halbach magnet arrays are fixed, and the single magnet is attached to a moving part.…”

“…The total size of the magnet spring was confined to within 20 mm × 25 mm × 15 mm. In the given magnetic springs, the magnetic field around the moving magnet was more uniform when the height of the vertically magnetized magnet was greater than that of the horizontally magnetized magnet [20]. Thus, this was also imposed as an inequality constraint.…”

A high-bandwidth electromagnetic MEMS motion stage for scanning applications

“…The resulting force on the magnet was obtained by numerically integrating the Lorentz forces for infinitesimal coil elements due to the calculated magnetic field. This modeling approach is described in more detail in [22] and was implemented using MATLAB R 2 software. Figure 3 shows the force generated along the z-axis by one coil turn for varying diameter of the coil relative to the magnet width as a function of the vertical gap between the magnet and coil, where the coil current is 1 A.…”

“…The resulting force on the magnet was obtained by numerically integrating the Lorentz forces for infinitesimal coil elements due to the calculated magnetic field. This modeling approach is described in more detail in [22] and was implemented using MATLAB R 2 software.…”

Design and Analysis of a Novel 6-DOF Lorentzian Pointing Platform for Mass Transfer

“…The rotation around the axis of the cylinder is not controlled, so that the platform can be made to experience a full 360°. A new magnetic bearing using Halbach magnet arrays was used in the platform [15]. By using the magnetic bearing, the mass of the platform is compensated, and the stroke can be increased 4 times in vertical compared to Britcher [14].…”