Efficient Modeling Framework for the Synthesis of a Novel Magnet Array for Planar Motors

Abstract

INTRODUCTIONNowadays, given the rapid growth of industry electronification, there is a huge demand for microchips [1,2]. Therefore, the lithography industry has a necessity to improve the wafer positioning systems such that the throughput of the lithography machine is increased.To reduce the mass and to remove the cable slabs of the traditional double stroke wafer positioning system [3,4], a single stage system has been proposed in [5], consisting of two vertically attached stationary coils and a moving magnet array. A 2D schematic of this Dual Layer Planar Motor (DLPM) is shown in Fig. 1.The employed Halbach array does not utilize the entire available space. Furthermore, the magnet-to-magnet force within the array results in an undesired mover bending.This paper presents a framework to evaluate different novel magnet array architectures for the DLPM. Different configurations are analysed such that the secondary magnetization patterns of the Halbach array fully utilize the available space. Furthermore, an optimization is performed to enhance the thrust and levitation forces, while curtailing the magnet array bending.METHODThe presented tool is semi-analytical: the magnet flux densities are obtained analytically based on the Magnetic Charge Modeling method and the coil bed flux densities through the evaluation of the Biot-Savart’s law for a current carrying volume. The electromagnetic forces are derived numerically utilizing the Maxwell Stress Tensor.CONCLUSIONThe proposed analytical modeling method presents a framework for fast and accurate optimization of the DLPM. The model has been verified with Finite Element Modeling (FEM). Moreover, the approach improves the computation time compared to FEM in a maximum of a factor of 20. The optimization achieves a higher levitation force to weight ratio, even with the added magnet mass, according to Fig. 2. This releases stress from the power supply design as a lower heat dissipation requirement suffices.In the full paper the modeling approach will be elaborated on and the optimization for the thrust force is going to be addressed.   Efficient Modeling Framework for the Synthesis of a Novel Magnet Array for Planar Motors