Motor vehicle monitoring apparatus and associated method for controlling the electric current of an actuator

1. A motor vehicle control device for a motor vehicle having a motor vehicle voltage source connected in a vehicle electrical system and an actuator, the control device comprising:

a controller forming a component of a control loop for controlling an electric current of the actuator, wherein a voltage of the vehicle electrical system voltage is applied to the actuator;

a correction unit connected in a forward path of the control loop between said controller and a downstream actuating element of the control loop, said correction unit causing a correction factor proportional to a reciprocal of an instantaneous vehicle electrical system voltage to be applied to an actuating signal output by said controller;

a voltage measuring device for measuring the vehicle electrical system voltage between the vehicle voltage source and the correction unit, said voltage measuring device having an input; and

a lowpass filter preceding said input of said voltage measuring device, said lowpass filter configured to filter out disturbance frequencies of the vehicle electrical system voltage above a PWM frequency of a PWM generator disposed downstream of said correction unit in the controller circuit and used for controlling the actuating element by way of pulse width modulation signals.

2. The motor vehicle control device according to claim 1 , wherein the actuator is a solenoid valve.

3. The motor vehicle control device according to claim 2 , wherein the actuator is a solenoid control valve.

4. The motor vehicle control device according to claim 1 , wherein the actuator is operatively connected to a motor vehicle hydraulic device for an actuation thereof.

5. The motor vehicle control device according to claim 4 , wherein the motor vehicle hydraulic device is a clutch, a transmission, a pressure controller for a fuel injection system, or a hydraulic brake.

6. The motor vehicle control device according to claim 1 , wherein said controller is a dynamic digital controller.

7. The motor vehicle control device according to claim 1 , wherein said controller is a PI or PID controller.

8. The motor vehicle control device according to claim 1 , wherein said correction unit is a multiplier configured to apply a correction factor proportional to a reciprocal of an instantaneous vehicle electrical system voltage to the actuating signal output by said controller.

9. The motor vehicle control device according to claim 8 , wherein said correction unit is a multiplier for multiplying an actuating signal output by said controller by the correction factor in accordance with the relationship

CF

=

VA

VB

,

where

CF is the correction factor;

VB is the vehicle electrical system voltage; and

VA is a proportionality factor corresponding to the vehicle electrical system voltage at the operating point of the control loop for which the controller parameters of the controller are set in an optimized manner.

10. The motor vehicle control device according to claim 1 , wherein said correction unit is a divider configured to divide the actuating signal output by said controller by a correction factor proportional to an instantaneous vehicle electrical system voltage.

11. The motor vehicle control device according to claim 10 , wherein said correction unit is a divider configured to divide the actuating signal output by said controller by a correction factor in accordance with to the relationship

CF

*

=

VB

VA

,

where

CF* is the correction factor;

VB is the vehicle electrical system voltage; and

VA is a proportionality factor corresponding to the vehicle electrical system voltage at the operating point of the control loop for which the controller parameters of the controller are set in an optimized manner.

12. The motor vehicle control device according to claim 1 , wherein said lowpass filter is an integral part of the voltage measuring device.

13. The motor vehicle control device according to claim 1 , wherein said voltage measuring device is an analog/digital converter.

14. The motor vehicle control device according to claim 13 , wherein said voltage measuring device is a sigma-delta converter.

15. The motor vehicle control device according to claim 1 , which comprises a current measuring device connected in the feedback path of the control loop, said current measuring device determining an actual current of the actuator and deriving therefrom a measured controlled variable.

16. The motor vehicle control device according to claim 15 , which comprises a subtractor connected at the input of the control loop, said subtractor determining, from a difference between a given setpoint current and the measured controlled variable, a deviation signal and feeding the deviation signal to an input of the controller.

17. The motor vehicle control device according to claim 15 , wherein said current measuring device is an analog/digital converter.

18. The motor vehicle control device according to claim 17 , wherein said current measuring device is a sigma-delta converter.

19. A method of controlling an electric current of an actuator by way of a controller of a motor vehicle control device as a component of a control loop, the method which comprises:

applying a vehicle electrical system voltage of a motor vehicle voltage source to the actuator;

providing a correction unit in the forward path of the control loop between the controller and a downstream actuating element of the control loop, and causing with the correction unit a correction factor proportional to a reciprocal of an instantaneous vehicle electrical system voltage to be applied to the actuating signal output by the controller of the control loop;

providing a voltage measuring device for measuring the vehicle electrical system voltage between the vehicle voltage source and the correction unit, the voltage measuring device having an input; and

providing a lowpass filter preceding the input of the voltage measuring device, the lowpass filter configured to filter out disturbance frequencies of the vehicle electrical system voltage above a PWM frequency of a PWM generator disposed downstream of the correction unit in the controller circuit and used for controlling the actuating element by way of pulse width modulation signals.

20. A method of controlling an electric current of an actuator, the method which comprises:

providing a controller forming a component of a control loop for controlling an electric current of the actuator, wherein a voltage of the vehicle electrical system voltage is applied to the actuator;

applying a vehicle electrical system voltage of a motor vehicle voltage source to the actuator;

providing a correction unit connected in a forward path of the control loop between the controller and a downstream actuating element of the control loop, the correction unit causing a correction factor proportional to a reciprocal of an instantaneous vehicle electrical system voltage to be applied to an actuating signal output by the controller;

providing a voltage measuring device for measuring the vehicle electrical system voltage between the vehicle voltage source and the correction unit, the voltage measuring device having an input; and

providing a lowpass filter preceding the input of the voltage measuring device, the lowpass filter configured to filter out disturbance frequencies of the vehicle electrical system voltage above a PWM frequency of a PWM generator disposed downstream of the correction unit in the controller circuit and used for controlling the actuating element by way of pulse width modulation signals.