Rotating electrical machine, in particular alternator for motor vehicle

Rotary electric machine of the type comprising a stator (12) with windings, a rotor (13) provided with a rotary shaft (15), a front bearing and a rear bearing on which the stator windings are fixed and in which the rotor shaft is mounted so that it can rotate, an arrangement for rectifying the current produced by the rotary electric machine, which comprises a number of positive diodes supported by a heat dissipater in the overall form of a support plate and a number of negative diodes supported by support means in the form of a plate advantageously forming part of the rear bearing, these plates being axially juxtaposed and fixed to the rear bearing, and a device providing cooling by circulating an axial stream of a cooling fluid through axial openings in said plates, at least some openings in the plate (9) supporting the positive diodes (8) being provided with a great many cooling ribs which have the shape of fins (118, 119) extending practically radially across the support plate from the radially inner edge thereof, an opening (120) for the passage of the cooling fluid advantageously being provided between each pair of adjacent fins (118, 119), characterized in that some fins (118), known as first fins, extend practically as far as the outer periphery of the plate (9) supporting the positive diodes (8).