Ventilation Structure Improvement of Large Motors Using 3-D Multi-Physical Coupled-Field Finite-Element Analysis

This paper investigates a 3-D coupled-field finite-element method (FEM) used in simulation of temperature distribution in air-cooled asynchronous induction motor. The temperature rise in motor is due to Joule´s losses in stator windings and the induced eddy current in squirrel cages, and heat dissipation by air convection and solid conduction. The Joule´s losses calculated by 3-D eddy- current field analysis are used as the input for the thermal field analysis, which is deeply dependent on accurate air fluid field analysis. A novel multi-component fluid model is proposed to deal with the influence of rotor rotation upon the air convection. Through the coupled-field calculation, we propose a new ventilation structure of a 15-phase motor to improve the cooling performance.