Method for controlling the voltage of an apparatus fitted in a motor vehicle

1. Method for controlling the voltage of an electrical apparatus ( 3 ) of a motor vehicle, using pulse width modulated signals, said electrical apparatus ( 3 ) being capable of being electrically modeled in the form of an equivalent circuit (RLC) comprising a first branch, comprising a capacitor (C) connected in parallel with a second branch, comprising a resistor (R) and an induction coil (L) connected in series, said method, executed by a control unit of the vehicle, comprising the steps of:

measuring (E 2 ) the voltage (V) at the terminals of the apparatus and measuring (E 3 ) the strength (I) of the output current of the apparatus ( 3 ),

calculating (E 4 ) the values of resistance (R), coil inductance (L) and capacitance (C) of the equivalent circuit (RLC) on the basis of the measured current strength (I) and the measured voltage (V),

comparing (E 7 , E 8 , E 9 ) the calculated values of resistance (R), inductance (L) and capacitance (C) with values of resistance (R), inductance (L) and capacitance (C), respectively, stored in a storage area ( 20 ) of the electronic control unit ( 1 ), and

initiating (E 12 ) an action if the difference between at least one of the calculated values and the corresponding stored value is above a predetermined threshold.

2. Method according to claim 1 , comprising a step (E 11 ) of storing the calculated values of resistance (R), inductance (L) and capacitance (C) if the difference between at least one of the estimated values and the corresponding stored value is above a predetermined threshold.

3. Method according to claim 1 , wherein a plurality of values of resistance (R), a plurality of values of inductance (L) and a plurality of values of capacitance (C) being stored in the storage area ( 20 ), the standard deviation or the variance are calculated over the set of stored values of resistance (R), inductance (I) and capacitance (C) respectively, so as to detect a drift of these values over time.

4. Method according to claim 1 , wherein the action that is initiated consists in a modification of the pulse width of the voltage control signals, for example if the measured current strength (I) is different from a predetermined value of strength.

5. Method according to claim 1 , wherein the action that is initiated consists in an alert enabling the occurrence of a failure to be anticipated, for example if the measured current strength (I) drifts significantly over time relative to a predetermined value of strength.

6. Method according to claim 1 , wherein the action that is initiated consists in a failure information message comprising values of resistance (R), inductance (L) and capacitance (C) stored in the storage area ( 20 ) to enable the voltage control of the electrical apparatus ( 3 ) to be analyzed when a failure of said apparatus ( 3 ) occurs.

7. Electronic control unit ( 1 ) for controlling the voltage of an electrical apparatus ( 3 ) of a motor vehicle, using pulse width modulated signals, said electrical apparatus ( 3 ) being capable of being electrically modeled in the form of an equivalent circuit (RLC) comprising a first branch, comprising a capacitor (C) connected in parallel with a second branch, comprising a resistor (R) and an induction coil (L) connected in series, said electronic control unit ( 1 ) comprising:

a module ( 10 ) for controlling the voltage of the electrical apparatus ( 3 ) by pulse width modulated signals,

a storage area ( 20 ) capable of storing values of resistance (R), coil inductance (L) and capacitance (C) of the equivalent circuit (RLC),

a module ( 30 ) for measuring the voltage at the terminals of the electrical apparatus ( 3 ) and the strength of the output current of the electrical apparatus ( 3 ), and

a module ( 40 ) for calculating the values of resistance (R), inductance (L) and capacitance (C) of the equivalent circuit (RLC) on the basis of the measured current strength (I) and the measured voltage (V), and for comparing the calculated values of resistance (R), inductance (L) and capacitance (C) with the values of resistance (R), inductance (L) and capacitance (C), respectively, stored in the storage area ( 20 ), and

a module ( 50 ) for initiating an action if the difference between at least one of the calculated values and the corresponding stored value is above a predetermined threshold.

8. Electronic control unit ( 1 ) according to claim 7 , configured to store calculated values of resistance (R), inductance (L) and capacitance (C) in the storage area ( 20 ) if the difference between at least one of the estimated values and the corresponding stored value is above a predetermined threshold.

9. Electronic control unit ( 1 ) according to claim 7 , wherein, a plurality of values of resistance (R), a plurality of values of inductance (L) and a plurality of values of capacitance (C) being stored in the storage area ( 20 ), the electronic control unit ( 1 ) is configured to calculate the standard deviation or the variance over the set of stored values of resistance (R), inductance (I) and capacitance (C), respectively, so as to detect a drift of these values over time.

10. Motor vehicle comprising at least one electrical apparatus ( 3 ) whose voltage can be controlled by pulse width modulated signals, and an electronic control unit ( 1 ) according to claim 7 .

11. Method according to claim 2 , wherein a plurality of values of resistance (R), a plurality of values of inductance (L) and a plurality of values of capacitance (C) being stored in the storage area ( 20 ) , the standard deviation or the variance are calculated over the set of stored values of resistance (R), inductance (I) and capacitance (C) respectively, so as to detect a drift of these values over time.

12. Method according to claim 2 , wherein the action that is initiated consists in a modification of the pulse width of the voltage control signals, for example if the measured current strength (I) is different from a predetermined value of strength.

13. Method according to claim 3 , wherein the action that is initiated consists in a modification of the pulse width of the voltage control signals, for example if the measured current strength (I) is different from a predetermined value of strength.

14. Method according to claim 2 , wherein the action that is initiated consists in an alert enabling the occurrence of a failure to be anticipated, for example if the measured current strength (I) drifts significantly over time relative to a predetermined value of strength.

15. Method according to claim 3 , wherein the action that is initiated consists in an alert enabling the occurrence of a failure to be anticipated, for example if the measured current strength (I) drifts significantly over time relative to a predetermined value of strength.

16. Method according to claim 4 , wherein the action that is initiated consists in an alert enabling the occurrence of a failure to be anticipated, for example if the measured current strength (I) drifts significantly over time relative to a predetermined value of strength.

17. Method according to claim 2 , wherein the action that is initiated consists in a failure information message comprising values of resistance (R), inductance (L) and capacitance (C) stored in the storage area ( 20 ) to enable the voltage control of the electrical apparatus ( 3 ) to be analyzed when a failure of said apparatus ( 3 ) occurs.

18. Method according to claim 3 , wherein the action that is initiated consists in a failure information message comprising values of resistance (R), inductance (L) and capacitance (C) stored in the storage area ( 20 ) to enable the voltage control of the electrical apparatus ( 3 ) to be analyzed when a failure of said apparatus ( 3 ) occurs.

19. Method according to claim 4 , wherein the action that is initiated consists in a failure information message comprising values of resistance (R), inductance (L) and capacitance (C) stored in the storage area ( 20 ) to enable the voltage control of the electrical apparatus ( 3 ) to be analyzed when a failure of said apparatus ( 3 ) occurs.

20. Method according to claim 5 , wherein the action that is initiated consists in a failure information message comprising values of resistance (R), inductance (L) and capacitance (C) stored in the storage area ( 20 ) to enable the voltage control of the electrical apparatus ( 3 ) to be analyzed when a failure of said apparatus ( 3 ) occurs.