Control of an inductive load by pulse width modulation

1. A device for controlling an inductive load by pulse width modulation, in which, on the basis of a periodic set point control signal (PWM) having a given set point duty cycle (dcom), said set point control signal (PWM) is, in each period of said set point control signal (PWM), in a first logic state determined from the high and low logic states for at least a first duration (t0), and is in the other logic state during the rest of the period, the device comprising:

a control unit ( 2 ) arranged to generate control signals (S 21 , S 31 ) activating the inductive load, on the basis of the set point control signal (PWM) and with current and voltage variations (slew rate);

a first counter ( 3 ) arranged to determine the first duration (t0) on the basis of the set point control signal (PWM); and

a second counter ( 4 ) arranged to determine a second duration (t0−td2) for which a logic signal (L_Out) corresponding to an effective control signal (V, OUT) observed in the load (O 1 ) is in the first determined logic state,

wherein the control unit ( 2 ) is configured to slave the second duration to the first duration, and

wherein the first counter ( 3 ) and the second counter ( 4 ) are replaced by an up-down counter ( 5 ) arranged to count at the rate of the edges of a clock signal (CLK) when only the set point control signal is in the first logic state, and to count downward at the rate of the edges of said clock signal (CLK) when only the logic signal (L_Out) is in said first logic state, the control unit ( 2 ) being configured so that the up-down counter ( 5 ) reaches a negative value.

2. A device for controlling an inductive load by pulse width modulation, in which, on the basis of a periodic set point control signal (PWM) having a given set point duty cycle (dcom), said set point control signal (PWM) is, in each period of said set point control signal (PWM), in a first logic state determined from the high and low logic states for at least a first duration (t0), and is in the other logic state during the rest of the period, the device comprising:

a control unit ( 2 ) arranged to generate control signals (S 21 , S 31 ) activating the inductive load, on the basis of the set point control signal (PWM) and with current and voltage variations (slew rate);

a first counter ( 3 ) arranged to determine the first duration (t0) on the basis of the set point control signal (PWM); and

a second counter ( 4 ) arranged to determine a second duration (t0−td2) for which a logic signal (L_Out) corresponding to an effective control signal (V, OUT) observed in the load (O 1 ) is in the first determined logic state,

wherein the control unit ( 2 ) is configured to slave the second duration to the first duration, and

wherein the first counter ( 3 ) is arranged to count at the rate of the edges of a clock signal (CLK), starting from an edge of the set point control signal (PWM) that causes said set point control signal (PWM) to switch to the first logic state, and continuing to an edge of the set point control signal (PWM) that causes said set point control signal (PWM) to switch to the other logic state.

3. The device as claimed in claim 2 , wherein the control unit ( 2 ) is configured to generate a signal (Reset A) resetting the first counter ( 3 ) in response to the edge of the set point control signal (PWM) that causes said set point control signal (PWM) to switch to the other logic state, after the current count value of said first counter ( 3 ) has been saved to a register.

4. The device as claimed in claim 3 , wherein the control unit ( 2 ) is configured to generate a signal (Reset_B) for resetting the second counter ( 4 ) when the current count value of the second counter ( 4 ) reaches the count value of the first counter ( 3 ) saved to the register.

5. The device as claimed in claim 4 , wherein the control unit ( 2 ) is also configured to generate control signals (S 21 , S 31 ) for deactivating the inductive load when the current count value of the second counter ( 4 ) reaches the count value of the first counter ( 3 ) saved to the register.

6. The device as claimed in claim 2 , wherein the second counter ( 4 ) is arranged to count at the rate of the edges of a clock signal (CLK), starting from an edge of the logic signal (L_Out) corresponding to the effective control signal (OUT) in the load that causes said logic signal (L_Out) to switch to the first logic state, and continuing to an edge of the logic signal (L_Out) that causes said logic signal to switch to the other logic state.

7. The device as claimed in claim 3 , wherein the second counter ( 4 ) is arranged to count at the rate of the edges of a clock signal (CLK), starting from an edge of the logic signal (L_Out) corresponding to the effective control signal (OUT) in the load that causes said logic signal (L_Out) to switch to the first logic state, and continuing to an edge of the logic signal (L_Out) that causes said logic signal to switch to the other logic state.

8. A device for controlling an inductive load by pulse width modulation, in which, on the basis of a periodic set point control signal (PWM) having a given set point duty cycle (dcom), said set point control signal (PWM) is, in each period of said set point control signal (PWM), in a first logic state determined from the high and low logic states for at least a first duration (t0), and is in the other logic state during the rest of the period, the device comprising:

a control unit ( 2 ) arranged to generate control signals (S 21 , S 31 ) activating the inductive load, on the basis of the set point control signal (PWM) and with current and voltage variations (slew rate);

a first counter ( 3 ) arranged to determine the first duration (t0) on the basis of the set point control signal (PWM); and

a second counter ( 4 ) arranged to determine a second duration (t0−td2) for which a logic signal (L_Out) corresponding to an effective control signal (V, OUT) observed in the load (O 1 ) is in the first determined logic state,

wherein the control unit ( 2 ) is configured to slave the second duration to the first duration, and

wherein the second counter ( 4 ) is arranged to count at the rate of the edges of a clock signal (CLK), starting from an edge of the logic signal (L_Out) corresponding to the effective control signal (OUT) in the load that causes said logic signal (L_Out) to switch to the first logic state, and continuing to an edge of the logic signal (L_Out) that causes said logic signal to switch to the other logic state.

9. The device as claimed in claim 8 , wherein the control unit ( 2 ) is configured to generate a signal (Reset_B) for resetting the second counter ( 4 ) when the current count value of the second counter ( 4 ) reaches the count value of the first counter ( 3 ) saved to the register.

10. A method for controlling an inductive load by pulse width modulation on the basis of a periodic set point control signal (PWM) having a given set point duty cycle (dcom), where said set point control signal (PWM) is, in each period of said set point control signal (PWM), in a first logic state determined from the high and low logic states for at least a first duration (t0), and is in the other logic state during the rest of the period, the method comprising:

generating control signals (S 21 , S 31 ) activating the inductive load, on the basis of the set point control signal (PWM) and with current and voltage variations (slew rate);

determining, with the aid of a first counter ( 3 ), the first duration (t0) on the basis of the set point control signal (PWM);

determining, by means of a second counter ( 4 ), a second duration (t0−td2) for which a logic signal (L_Out) corresponding to an effective control signal (V, OUT) observed in the load (O 1 ) is in the first determined logic state; and

slaving the second duration (t0−td2) to the first duration (t0),

wherein the first counter ( 3 ) counts at the rate of the edges of a clock signal (CLK), starting from an edge of the set point control signal (PWM) that causes said set point control signal (PWM) to switch to the first logic state, and continuing to an edge of the set point control signal (PWM) that causes said set point control signal (PWM) to switch to the other logic state.

11. The method as claimed in claim 10 , wherein the first counter ( 3 ) is reinitialized in response to the edge of the set point control signal (PWM) that causes said set point control signal (PWM) to switch to the other logic state, after the current count value of said first counter ( 3 ) has been saved to a register.

12. The method as claimed in claim 10 , wherein the second counter ( 4 ) is reinitialized when the current count value of the second counter ( 4 ) reaches the count value of the first counter ( 3 ) saved to the register.

13. The method as claimed in claim 12 , wherein the control unit ( 2 ) is also configured in such a way that control signals (S 21 , S 31 ) are generated for deactivating the inductive load when the current count value of the second counter ( 4 ) reaches the count value of the first counter ( 3 ) saved to the register.

14. The method as claimed in claim 10 , wherein the second counter ( 4 ) counts at the rate of the edges of a clock signal (CLK), starting from an edge of the logic signal (L_Out) corresponding to the effective control signal (OUT) in the load that causes said logic signal to switch to the first logic state, and continuing to an edge of the logic signal (L_Out) that causes said logic signal (L_Out) to switch to the other logic state.

15. The method as claimed in claim 11 , wherein the second counter ( 4 ) counts at the rate of the edges of a clock signal (CLK), starting from an edge of the logic signal (L_Out) corresponding to the effective control signal (OUT) in the load that causes said logic signal to switch to the first logic state, and continuing to an edge of the logic signal (L_Out) that causes said logic signal (L_Out) to switch to the other logic state.

16. The method as claimed in claim 11 , wherein the second counter ( 4 ) is reinitialized when the current count value of the second counter ( 4 ) reaches the count value of the first counter ( 3 ) saved to the register.

17. A method for controlling an inductive load by pulse width modulation on the basis of a periodic set point control signal (PWM) having a given set point duty cycle (dcom), where said set point control signal (PWM) is, in each period of said set point control signal (PWM), in a first logic state determined from the high and low logic states for at least a first duration (t0), and is in the other logic state during the rest of the period, the method comprising:

generating control signals (S 21 , S 31 ) activating the inductive load, on the basis of the set point control signal (PWM) and with current and voltage variations (slew rate);

determining, with the aid of a first counter ( 3 ), the first duration (t0) on the basis of the set point control signal (PWM);

determining, by means of a second counter ( 4 ), a second duration (t0−td2) for which a logic signal (L_Out) corresponding to an effective control signal (V, OUT) observed in the load (O 1 ) is in the first determined logic state; and

slaving the second duration (t0−td2) to the first duration (t0),

wherein the second counter ( 4 ) counts at the rate of the edges of a clock signal (CLK), starting from an edge of the logic signal (L_Out) corresponding to the effective control signal (OUT) in the load that causes said logic signal to switch to the first logic state, and continuing to an edge of the logic signal (L_Out) that causes said logic signal (L_Out) to switch to the other logic state.