Method for regulating the current through an electromagnetic actuator

A method for regulating current through an electromagnetic actuator, the electromagnetic actuator, a first switch and a current-measuring circuit forming a series circuit, a free-wheeling diode being parallel-connected to the electromagnetic actuator, the method comprising:

• closing and opening the first switch by an automatic control and a pulse generator using a pulse width modulation signal (PWM) in such a way that current flowing through the electromagnetic actuator and measured by the current-measuring circuit is regulated to a setpoint value;
• altering a time duration of one on and off switching cycle of the PWM signal;
• and
• superimposing a dither function in a form of a low-frequency oscillation on the PWM signal, wherein the current flowing through the electromagnetic actuator and measured by the current-measuring circuit is freed from the dither function by a corrector.

A memory device storing a computer program, the computer program when executed on a computer, causing the computer to perform the following:

• closing and opening a first switch by an automatic control and a pulse generator using a pulse width modulation signal (PWM) in such a way that current flowing through an actuator and measured by a current-measuring circuit is regulated to a setpoint value;
• altering a time duration of one on and off switching cycle of the PWM signal;
• and
• superimposing a dither function in a form of a low-frequency oscillation on the PWM signal, wherein for the dither function, a dither value is added to or subtracted from each pulse of the PWM signal, wherein a time duration during which the dither value is added to the pulse of the PWM signal is equal to a time duration during which the dither value is subtracted from the pulses, and wherein the time duration during which the dither value is added to the pulses and the time duration during which the dither value is subtracted from the pulses yield a total time duration which is a multiple of the time duration of one on and off switching cycle of the PWM signal.

A control unit for regulating current through an electromagnetic actuator, the electromagnetic actuator, a first switch and a current-measuring circuit forming a series circuit, a free-wheeling diode being parallel-connected to the electromagnetic actuator, and the control unit, comprising:

• an automatic control;
• and
• a pulse generator by which the first switch is closed and opened using a pulse width modulation (“PWM”) signal in such a way that the current flowing through the electromagnetic actuator and measured by the current-measuring circuit is regulated to a setpoint value;
• wherein the control unit is configured to alter a time duration of one on and off switching cycle of the PWM signal and superimpose a dither function in a form of a low-frequency oscillation on the PWM signal, wherein for the dither function, a dither value is added to or subtracted from each pulse of the PWM signal, wherein a time duration during which the dither value is added to the pulse of the PWM signal is equal to a time duration during which the dither value is subtracted from the pulses, and wherein the time duration during which the dither value is added to the pulses and the time duration during which the dither value is subtracted from the pulses yield a total time duration which is a multiple of the time duration of one on and off switching cycle of the PWM signal.