Dimensionnement d'une machine à double excitation de structure innovante pour une application alternateur automobile : comparaison à des structures classiques

The increase of electrical power demand in vehicles and requirements for machines for hybrid vehicles encouraged to explore alternative structures of machines to the claw pole alternator. Here, an innovative structure with double parallel excitation has been studied for the alternator needs. The introduction of the magnets provides a huge increasing of power, it has been highlighted by comparing this structure to a conventional salient pole machine, the power has been squarely lined. The specification fixed (3.2 kW) for this study was achieved without difficulties. The double excitation chosen allows the flux weakening, and therefore the output control with a simple diode bridge rectifier. The experimental and theoretical study has shown the effectiveness of the flux control by rotor current and without any risk of demagnetization of magnets. The experimental comparison in the same dimensions with a claw pole structure with interpolar magnets shows the supremacy of this latest one. In output due to its global excitation coil allowing more ampere turns, and in efficiency for low power due to its total and local field weakening. However, for high power, the double excitation machine, with its two dimensional structure, has more efficiency due to its low iron loss. Further study may show a good positioning of this structure for engine applications in hybrid vehicles. A little comparison of performance with the claw pole machine showed that this one is not automatically better