Coupled Electromagnetic and Thermal Design of Miniaturized Permanent Magnet Linear Motors for Sliding Door Applications

摘要

The design process for permanent magnet linear motors (PMLM) is similar to that used for their rotary counterparts. A number of electro-technical equations are used to get the best design for a specific application. Nevertheless, there are two issues that differ from the design of a standard rotary machine that must be considered. The first one is the intrinsic asymmetry of the magnetic circuit, which makes the flux distribution different from pole to pole. The second one is the particular geometry and constraints of the thermal circuit, which is crucial for the design of miniaturize linear motors. This paper presents an analytical method for computing the flux distribution in a surface-mounted PMLM. The method, based on the equivalent magnetic circuit method, considers the saturation of the material, the leakage at the end of the motor and the asymmetrical distribution of the magnetic flux. Additionally, an analytical lumped parameter thermal model for linear drives that gives results for both transient and steady-state temperatures is described. Validation of the models is performed by using Finite Element and Computer Fluid Dynamics software. Finally, both magnetic and thermal circuits have been used to design a miniaturized PMLM to drive a sliding door to experimentally verify its goodness.