Squirrel cage rotor for power controlled AC async. motor - has ferromagnetic sleeve partly covering surface for low speeds without efficiency loss

摘要

The squirrel cage rotor for power controlled alternating current, asynchronous motors has a laminated iron core enclosed in the conducting cage. A ferromagnetic sleeve (15) is set into the outer surface of the cage/core, but covers only a 1/4 to 3/4 of the available surface area. the cage is constructed from an aluminium/silicon alloy or another material having a higher resistivity than copper. The rotor may be also made from one or more laminated cores with separate cages. The advantage of allowing the ferromagnetic sleeve to cover only a part of the rotor surface lies in improving low-speed performance without a loss in motor efficiency due to eddy currents.