Three phase tooth-concentrated interspersed windings with low space harmonic content

The paper presents a new possibility of obtaining lower space harmonic content for the fractional-slot, tooth-concentrated windings by interspersing the phase windings. By using multiple layer windings it is possible to reduce or even to cancel some space sub-harmonics having as final result lower eddy current losses induced by the armature reaction in the iron structure of the rotor. The general method of multiplying the winding and relatively shifting by one (or more) slots is presented in the paper. The application of the method is developed for the general case of the windings having Z=2p±1 where, instead of double layers winding, the partial three or even four layers winding is obtained. The example of application is given for 15 slots, 14 poles, three phase concentrated windings which is presented and analyzed as primitive windings.