A linear brushless direct current motor design approach for seismic shake tables

The progress in material and manufacturing technologies enables the emergence of new research areas in electromagnetic actuator applications. Permanent magnet (PM) linear motors are preferred to achieve precise position control and to meet the need for high dynamic forces in the seismic shake tables that are used in analyzing reactions of structure models. The design approaches on the linear motors used in the seismic shake tables may vary depending on the desired force, stroke and acceleration values. Especially, the maximum width, the maximum depth, the maximum linear motor length in longitudinal direction and the maximum travelling distance parameters are the primary design criteria in seismic shake table drive systems. In this paper, a design approach for a linear PM brushless direct current (BLDC) motor with high force/volume, force/weight and force/input power ratios is developed. The design was analyzed using two-dimensional (2D) and three-dimensional (3D) finite element method (FEM) approaches through the ANSYS Maxwell software. The mathematically designed linear BLDC motor was manufactured and subjected to displacement, acceleration and force tests that are used in seismic analyses. The results of the experimental tests validate the convenience of the proposed design approach and the selected parameters.