The well known semi-empirical methods of the commutation do not meet our expectations. Thus, we have developed a specific method linking numerical calculations for the iron parts (by using the FLUX2D program in magnetostatic and in transient magnetic (i.e., use of the moving air gap) and an analytical calculation for the end windings. The approach is as follows: numerical calculation using a finite element method of the inductances and of the mutuals: of the commutating poles, of each specified rotor conductor, of conductor to conductor located in the same slot, and from slot to slot for each angular position of the rotor; tridimensional analytical calculation of the field in each space point by integration of the Biot and Savart formulation and by using the method of the electrical images: proper inductance of the end windings, and mutuals of the different windings. The calculation results are confirmed by experimental tests realised on an instrumented motor.
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