A Multiphysics Design Methodology Applied to a High-Force-Density Short-Duty Linear Actuator

This paper presents a coupled electromagnetic and thermal design methodology which addresses the problem of balancing accuracy against computation time. A case study on a short-duty permanent-magnet (PM) linear actuator is used to illustrate the approach. The proposed method employs a two-dimensional electromagnetic finite-element (FE) model coupled with a detailed thermal equivalent circuit (TEC) model which is automatically constructed and parameterized using geometric and material data. A numerical method of estimating the equivalent thermal properties of the winding amalgam is used along with published empirically derived convection and radiation heat transfer correlations. The relatively high number of network nodes and more accurate thermal material properties minimizes model calibration and allows improved temperature prediction, including winding hot spots, while maintaining a low computational cost for both steady-state and transient analyses. A comparison between experimental and theoretical actuator performance shows that the design methodology provides good accuracy electromagnetic and transient thermal performance predictions without the need for direct model calibration and can yield an optimized design within an acceptable time frame.