The invention relates to an electric machine with a squirrel-cage rotor.
Asynchronous machines typically have rotors in form of a cage winding, whereby a respective rod is inserted in each of the slots, with the rods being connected at their respective end faces on the rotor by cage rings. Rods and cage rings are fabricated from aluminum or aluminum alloys by die casting, and have a higher resistance. However, copper, bronze or brass can also be used as electric conductors. The solid rods of the cage winding are typically inserted in the rotor without insulation and joined with the cage rings by soldering.
Disadvantageously, the cage rods have to be connected with the cage rings in a separate manufacturing step. Moreover, the projection of the rods at the end faces of the rotor does not contribute to torque generation. In addition, vibration fatigue frequently occurs due to the relatively rigid construction of the squirrel-cage, in particular at the solder joints.