Experimental performance assessent of multiphase alternators supplying multiple AC/DC power converters

DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more (N) three-phase windings and feeds the DC load through more (N) cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number (N) of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits (in terms of DC output current quality and field current ripple) are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.