Electric Motor Windings Comparison

With a con­cen­trat­ed wind­ing, the sta­tor is always wound exact­ly over one tooth. This has sig­nif­i­cant advan­tages in the man­u­fac­ture of the sta­tor. For exam­ple, already fin­ished wind­ings can sim­ply be pushed onto the sta­tor. How­ev­er, the design of the sta­tor’s teeth must be designed for this. A major advan­tage of a con­cen­trat­ed wind­ing is the very small wind­ing head at the top and bot­tom of the motor. In a dis­trib­uted wind­ing, this wind­ing head is larg­er because of the over­lap of the wind­ings. Due to the small­er wind­ing head of con­cen­trat­ed wind­ings, the ohmic loss­es in the low­er speed range, are low­er all for a dis­trib­uted wind­ing. When using a clas­si­cal design of an elec­tric motor with a con­cen­trat­ed devel­op­ment, the back EMF is trape­zoidal. As a result, high torque can be gen­er­at­ed with this type of wind­ing, espe­cial­ly in the low­er range. How­ev­er, this does not mean that it also results in high effi­cien­cy. This is because the main dis­ad­van­tage of a con­cen­trat­ed wind­ing is the har­mon­ics that are gen­er­at­ed, which can lead to high loss­es, espe­cial­ly at high speeds. These loss­es can occur in the wind­ings in the lam­i­na­tions as well as in per­ma­nent mag­nets. Con­cen­trat­ed wind­ings are pri­mar­i­ly used for motors that are short and have a large diam­e­ter. An exam­ple of this is wheel hub dri­ves for elec­tric bicy­cles with­out gears. Con­cen­trat­ed wind­ings are also used for dri­ves that require high dynam­ics and effi­cien­cy is not so crit­i­cal. Anoth­er dis­ad­van­tage of con­cen­trat­ed wind­ings is a not insignif­i­cant torque rip­ple. This can be com­pen­sat­ed, for exam­ple, by mov­ing the mag­nets on the rotor rel­a­tive to each oth­er or by shap­ing the mag­nets accordingly.