Method and device for failsafe control of an alternator/starter system of the micro-hybrid type, and corresponding micro-hybrid system

A method is implemented in a vehicle having an electronic control unit (15), vehicle sensors, a data communication bus (16), and an on-board electrical network. The micro-hybrid system (1) comprises at least one rotary electrical machine (2) which is provided with a device (8) for detection of rotation, power circuits (14) comprising an inverter (7) and an excitation circuit (4) which supplies the rotary electrical machine (2), and a rectifier (11) which is supplied by the said rotary electrical machine (2), energy conversion circuits (12) which are connected to an energy storage device (9) which is supplied by the rectifier (11), a first circuit (13) to control the power circuits (14), and a second circuit (25) to control the energy conversion circuits (12). The method generates control signals (Dd. Exc., Dd. Ond., Auth. Exc., Auth. Ond.) on the basis of first information signals (Capt. Véh.) which are representative of a state of functioning of the vehicle, obtained from the vehicle sensors; and generates b