Control device for controlling a motor vehicle alternator of the type which controls a DC voltage (B+A) generated by said alternator at a predefined voltage setpoint (Uo) by controlling the intensity of an excitation current (I EXC ) flowing in an excitation circuit including an excitation winding of a rotor of said alternator and furthermore maintaining a current temperature (T) of said alternator below a predefined maximum admissible temperature (T max ), comprising a voltage control loop including: - acquisition means for acquiring said DC voltage (B+A) and which delivers a measured voltage (U b+ ) ; - a first comparator for comparing said measured voltage (U b+ ) of said voltage setpoint (Uo) and which generates a voltage error (ε V ); and in that it furthermore comprises a temperature control loop including: - a first temperature measurement/estimation means which delivers said current temperature (T); - a second comparator which generates a temperature error (ε T ) between said maximum admissible temperature (T max ) and said current temperature (T) ; - input means for inputting a current rotation speed (V) of said alternator ; characterized in that the voltage control loop includes: - first conditioning means for conditioning said voltage error (ε V ) which deliver an input excitation percentage (r i ) ; - a saturation module which delivers, in accordance with said input excitation percentage (r i ), an output excitation percentage (r o ) limited to a maximum admissible excitation percentage (rmax); - a generator for generating a pulse-width modulated signal (PWM) having a duty cycle equal to said output excitation percentage (r o ); - a semi-conductor switch controlled by said pulse-width modulated signal (PWM) and which controls said intensity (I EXC ) ; and in that the temperature control loop includes a control module delivering said maximum admissible excitation percentage (r max ) in accordance with said temperature error (ε T ) and with a speed correction (V cor ) delivered by speed correction means according to a predefined correction law in accordance with said current rotation speed (V). - acquisition means for acquiring said DC voltage (B+A) and which delivers a measured voltage (U b+ ) ; - a first comparator for comparing said measured voltage (U b+ ) of said voltage setpoint (Uo) and which generates a voltage error (ε V ); - a first temperature measurement/estimation means which delivers said current temperature (T); - a second comparator which generates a temperature error (ε T ) between said maximum admissible temperature (T max ) and said current temperature (T) ; - input means for inputting a current rotation speed (V) of said alternator ; - first conditioning means for conditioning said voltage error (ε V ) which deliver an input excitation percentage (r i ) ; - a saturation module which delivers, in accordance with said input excitation percentage (r i ), an output excitation percentage (r o ) limited to a maximum admissible excitation percentage (rmax); - a generator for generating a pulse-width modulated signal (PWM) having a duty cycle equal to said output excitation percentage (r o ); - a semi-conductor switch controlled by said pulse-width modulated signal (PWM) and which controls said intensity (I EXC ) ; <EOS>