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.