Efficient cooling of speed controlled induction motors - involes placing rotor outside stator to act as fan

摘要

The main limitation on speed controlled asynchronous motors is the heating effects on the rotor, and the heat transfer from the rotor cooling air to the stator end windings. Better utilisation of the active material results from placing the rotor outside the stator as the rotor losses go directly out of the machine via the cooling air flow. The rotor is attached to the central shaft through the stator bore by radial ribs which can be designed to act as fans to draw cooling air through axial ducts under the stator core.