Combined stator windings in electric machines with same coils

The idea of combined windings is very old, but only a few motor windings have been built with them until today. Recently some releases were cast out about this topic, because the combined winding reduces the copper losses. The international claim IEC 60034 for more efficiency to reduce greenhouse gases pushes the factories to look for new ways of reducing the losses in electrical machines. A way to save energy is to build up asynchronous machines with copper cast rotors. Combined windings are a further possibility and avoid the higher costs caused by the copper rotor. A further application of combined windings is the high speed drives. Combined windings can be built up to generate a very small harmonic content so that the losses of permanent magnet rotors and its temperatures decrease. A problem of combined windings is that two kinds of coils will be needed. This paper shows a way to create one layer combined windings with only one sort of coils. By using this windings the higher costs will be narrowed. Examples of combined windings will be compared with conventional windings about copper losses and harmonic content.