FAST ANALYSIS OF MMF HARMONICS CONTENT IN THREE-PHASE ELECTRICAL MACHINES

Fractional-slot windings, tooth-concentrated windings, multilayer windings and other "new" windings have been gained a great interest over the last years due to some advantages that this type of windings provides for synchronous permanent magnet machines. In spite of theirs advantages, these windings exhibit high content of space harmonics in the air-gap magneto-motive force (MMF) distribution that can give rise unwanted effects in a.c. electrical machines. This paper aims to help the machine designer to select the proper winding configurations and to sort out the best winding layout. Firstly, the paper reminds the theoretical concepts based on star of slots and Fourier-series expansion of the air-gap MMF wave used to compute the winding characteristics. This classical method was implemented on the computer to quickly determine the values of the main winding factor, space harmonic content and differential leakage coefficient in order to identify the optimal winding structure. Thus, the proposed application becomes a helpful tool in the design process and can be applied for any type of single or three-phase winding layout irrespective of number of layer or number of conductor per slot.