Rotor for an electric machine and a method in an electric machine

A method of energizing a solid rotor of an electric machine, said method comprising guiding of electric current of the rotor and/or affecting to the resistivity thereof by means of a short circuit ring provided on the end face of the rotor, said short circuit ring being formed of a material having a better electrical conductivity than of a material of the rotor, wherein the short circuit ring is provided by attaching an annular piece provided from a bimetal sheet, such as steel-copper sheet, steel-aluminum sheet, steel-brass sheet, on the end face of the solid rotor from a such portion thereof which comprises material that essentially corresponds to the material of the rotor.

A rotor of an electric machine, said rotor comprising:

• a solid rotor portion having at least one end face;
• a short circuit ring attached to said at least one end face, said short circuit ring comprising a first portion adjacent said at least one end face and a second portion adjacent said first portion, said first portion and said second portion being formed of different materials.

A method of manufacturing a solid rotor for an electric machine, said method comprising the steps of:

• providing a solid rotor portion formed of a metal material, said rotor portion having at least one end face;
• providing a short circuit ring, said short circuit ring including a first portion and a second portion thereof, said first portion and second portion being formed of different conductive materials, said first portion comprising one side of said short circuit ring and said second portion comprising a second side of said short circuit ring;
• attaching said short circuit ring to said end face of said solid rotor portion, wherein said first portion of said short circuit ring is in contact with said end face.