Patent ID: 8115432

Claim:
A three-phase rotary electrical machine of an alternator-starter type, the electrical machine comprising: coils evenly distributed about a rotation axis of the machine; a switch associated with at least one coil of the coils, the switch forming part of a switch bridge with three arms, each of the arms corresponding to a phase and comprising at least two switches; a first sensor provided to deliver a periodic signal representing a position of the machine about the axis; and a control circuit provided to control, in a first mode, the conduction of the switch associated with at least one coil of the three coils on the basis of the periodic signal delivered by the first sensor so that conduction phases of the switch have a duration of around half the period of the periodic signal; the control circuit provided to control the switch in a second mode in which the conduction phases of the switch have a duration of around one third of the period of the periodic signal.