Cogging torque and torque ripple reduction of an electrically excited generator by alternatively extending rotor pole shoes

摘要

The present invention relates to a rotor (100) for an electrical machine, in particular an electrically excited generator for a wind turbine, The rotor (100) comprises a rotor body (101) extending along a circumferential direction (102) around a rotary axis (103) of the rotor (100), a rotor tooth with a first pole shoe (111) and a second pole shoe (121). The rotor tooth extends from a surface (105) of the rotor body (101) along a radial direction (104) with respect to the rotary axis (103). The first pole shoe (111) and the second pole shoe (121) are arranged at a free end of the rotor tooth. The first pole shoe (111) comprises a first offset (112) with respect to the second pole shoe (121) along a first direction (114) which is parallel to the circumferential direction (102). The second pole shoe (121) comprises a second offset (122) with respect to the first pole shoe (111) along a second direction (124) which is anti-parallel to the first direction (114).