A rotor of an induction motor includes a shaft, a ferromagnetic rotor core, first and second inductors axially bracketing the rotor core, and a rotor cage. The shaft extends along a stator axis, and the rotor core is disposed coaxially about the shaft. The rotor cage comprises first and second supports, and a plurality of cage bars. The supports are disposed axially between the rotor core and the first and second inductors, respectively. The cage bars surround the shaft, pass through the rotor core, are secured at the first and second supports, and are each electrically connected to both the first and second inductors.

A motor, including: a rotational shaft, a rotor, a stator, a housing, a first end cover, and a second end cover. The first end cover includes: a cover body including a bottom surface and a top surface, a bearing cavity, and a plurality of first bosses. The rotor is mounted on the rotational shaft; the stator is nested and installed inside the housing. The rotor is nested inside the stator; the first end cover and the second end cover are disposed on a rear end and a front end of the housing, respectively. The bearing cavity is disposed in the middle of the bottom surface of the cover body. The first bosses are circumferentially disposed at intervals on the top surface of the cover body. Outer side surfaces of the first bosses are located on a circle having a circle center coincident with the center of the cover body.

A female contact element for a slip ring motor with a power output >1 MW. The female contact element is configured for engagement with a male contact element to make an electrical connection between the female contact element and the male contact element. The female contact element is made of a CuBe-alloy.

A female contact element for a slip ring motor with a power output >1 MW. The female contact element is configured for engagement with a male contact element to make an electrical connection between the female contact element and the male contact element. The female contact element is made of a CuBe-alloy.

An electric motor includes a main winding coupled to a first line terminal, and first and second boost windings coupled in series to the main winding. A high-speed lead wire is coupled to a first tap between the main winding and the first boost winding, a medium-speed lead wire is coupled to a second tap between the first boost winding and the second boost winding, and a low-speed lead wire is coupled to a third tap after the second boost winding. A start winding has a first end coupled to the first line terminal and a second end. A capacitor has a first end series-coupled to the second end of the start winding and a second end coupled to the second tap. A switch coupled to a second line terminal is configured to couple the second line terminal to one of the high, medium, and low-speed lead wires.

An electric motor includes a main winding coupled to a first line terminal, and first and second boost windings coupled in series to the main winding. A high-speed lead wire is coupled to a first tap between the main winding and the first boost winding, a medium-speed lead wire is coupled to a second tap between the first boost winding and the second boost winding, and a low-speed lead wire is coupled to a third tap after the second boost winding. A start winding has a first end coupled to the first line terminal and a second end. A capacitor has a first end series-coupled to the second end of the start winding and a second end coupled to the second tap. A switch coupled to a second line terminal is configured to couple the second line terminal to one of the high, medium, and low-speed lead wires.

A rotor of an induction motor includes a shaft, a ferromagnetic rotor core, first and second inductors axially bracketing the rotor core, and a rotor cage. The shaft extends along a stator axis, and the rotor core is disposed coaxially about the shaft. The rotor cage comprises first and second supports, and a plurality of cage bars. The supports are disposed axially between the rotor core and the first and second inductors, respectively. The cage bars surround the shaft, pass through the rotor core, are secured at the first and second supports, and are each electrically connected to both the first and second inductors.