PWM control for solenoid valves - Circuit for the electronic control of an electromagnetic drive of a solenoid valve and method for controlling

Abstract

Circuit (100) for the electronic control of an electromagnetic drive of a solenoid valve, wherein the circuit (100) is configured to provide a control signal for the electromagnetic drive, which control signal has a high level and a low level, and the control signal has at least a first time interval (IV1) with a first duty cycle (TV1), an optional second time interval (IV2) with a second duty cycle (TV2), and a third time interval (IV1) with a third duty cycle (TV3), wherein the first, second, and third duty cycles (TV1, TV2, TV3) are less than one, and the first duty cycle (TV1) is greater than the second duty cycle (TV2), and the second duty cycle (TV2) is greater than the third duty cycle (TV3), and the length of the time intervals and the magnitude of the duty cycles are configured such thatthat the electromagnetic drive changes from a first operating state to a second operating state in the first time interval (IV1), optionally remains in the second operating state in the second time interval (IV2) and changes from the second operating state to the first operating state in the third time interval (IV3), , wherein the circuit (100) is designed to detect a supply voltage level of a supply voltage (VS) for the electromagnetic drive and to adjust one, several or all duty cycles (TV1, TV2, TV3) of the control signal based on the detected supply voltage level, and wherein the circuit (100) is configured to provide the control signal according to a logical AND operation of a first pulse width modulated (PWM) signal (PWM1) and a second pulse width modulated (PWM) signal (PWM2), wherein a level of the control signal is only at the high level when both the first pulse width modulated (PWM) signal (PWM1) and the second pulse width modulated (PWM) signal (PWM2) are at a high level at the same time.

Description

FIELD OF THE INVENTION

[0001] The invention relates to a circuit and a method for controlling an electromagnetic drive of a solenoid valve, in particular for control with a PWM signal. BACKGROUND

[0002] Solenoid valves with electromagnetic actuators have a wide range of applications. For example, there are pilot solenoid valves used in control heads that provide a certain pressure to the input side of a main valve. Pilot solenoid valves can, for example, control the air required to open and close a process valve. The electromagnetic actuator of solenoid valves typically comprises an armature and a coil, which is controlled, for example, with a pulse-width modulated control signal.

[0003] DE 10 2015 105 744 A1, DE 10 2016 207 564 B3 and DE 10 2010 001 004 A1 disclose generic control devices and methods for controlling a valve. SUMMARY OF THE INVENTION

[0004] It is an object of the invention to improve the control of solenoid valves with electromagnetic actuators compared to the prior art with regard to power consumption and complexity. In particular, the disadvantages of the prior art are to be eliminated or at least reduced.

[0005] The object is achieved according to the invention by the subject matter of the independent patent claims.

[0006] According to one aspect, a circuit is provided for electronically controlling an electromagnetic drive of a solenoid valve (also referred to as an electromagnetic valve). The circuit is configured to provide a control signal for the electromagnetic drive that has a high level (ON level) and a low level (OFF level), or alternates between the high level and the low level. The control signal has at least a first time interval with a first duty cycle, an optional second time interval with a second duty cycle, and a third time interval with a third duty cycle.

[0007] In the present context, the duty cycle is the ratio of ON time (duration or period of time during which the signal is at the high level) to the sum of OFF time (duration or period of time during which the signal is at the low level) and ON time. The sum of ON time and OFF time can correspond to the period or the fundamental frequency of the control signal, as is common with pulse-modulated signals (PWM signals, for example). Advantageously, the first time interval, optionally the second time interval and the third time interval follow one another in time, particularly advantageously directly one another. Furthermore, the first, second and third duty cycles are less than one. In other words, within the time intervals, the signal changes from high level to low level at least once or remains completely at zero. The first duty cycle is greater than the second duty cycle, and the second duty cycle is greater than the third duty cycle.The duration of the time intervals and the size of the duty cycles are advantageously designed such that the electromagnetic drive changes from a first operating state to a second operating state in the first time interval, remains in the second operating state in the optional second time interval, and changes from the second operating state to the first operating state in the third time interval. The circuit is designed to detect a supply voltage level of a supply voltage for the electromagnetic drive. The circuit is designed to adapt one, several, or all duty cycles of the control signal in response to this supply voltage level. The circuit can, for example,comprise an AD converter coupled to the power supply for detecting a supply voltage level and outputting corresponding digital data to the microcontroller in order to adjust one or more duty cycles, in particular the first and / or second duty cycle.

[0008] Numerous advantages can be achieved according to the above aspects. First, the level of a voltage supply in the form of an average or time-averaged level for the electromagnetic actuator can be adjusted by selecting the duty cycle. The energy consumption or power consumption of the electromagnetic actuator can be reduced when the electromagnetic actuator is in the second operating state, and the solenoid valve can switch selectively between the first and second operating states without the need to set further intermediate states between the operating states.

[0009] The control signal is advantageously a combination of two PWM signals. The combination is a logical AND operation. Accordingly, the control signal contains a first and a second signal component. The first and second signal components are each provided by a first PWM signal and a second PWM signal, which are combined accordingly.

[0010] The first PWM signal can have a first fundamental frequency, and the second PWM signal can have a second fundamental frequency. The first fundamental frequency can advantageously be higher than the second fundamental frequency. The first fundamental frequency and the first duty cycle can advantageously be large enough for the electromagnetic drive to switch from the first operating state to the second operating state. The first fundamental frequency and the second duty cycle can advantageously be large enough for the electromagnetic drive to remain in the second operating state.

[0011] The first fundamental frequency can, for example, also be a positive integer multiple of the second fundamental frequency.

[0012] Regardless of the ratio of the first fundamental frequency to the second fundamental frequency, the second PWM signal can also be configured such that at least the OFF time(s) of the second PWM signal is (are) longer than the OFF time(s) of the first PWM signal. Advantageously, both the ON time(s) and the OFF time(s) of the second PWM signal can be longer than the ON time(s) and OFF time(s) of the first PWM signal.

[0013] The first PWM signal may be configured to provide the first time interval having the first duty cycle and to provide the optional second time interval having the second duty cycle.

[0014] The second PWM signal can be configured to provide the third time interval with the third duty cycle. The second PWM signal can be the control variable for the solenoid valve.

[0015] The second PWM signal can be configured so that the solenoid valve is always fully opened and fully closed, thereby setting a specific target position of the solenoid valve on average over time.

[0016] The third duty cycle can advantageously be zero. The second time interval can advantageously be mandatory, i.e., not optional.

[0017] The circuit is configured to link the first PWM signal and the second PWM signal according to or by means of a link, in particular a logical link, and in particular a logical AND link, and to combine them into a single or the control signal. According to the principle of the AND link, the level of the control signal for the electromagnetic drive is only at the high level (ON level) when both the first PWM signal and the second PWM signal are simultaneously at a high level.

[0018] In one embodiment, the circuit may accordingly comprise an AND gate or a circuit or multiple gates with equivalent functionality. The AND gate or equivalent circuit then receives the first and second PWM signals and logically ANDs them.

[0019] The circuit may further include a transistor coupled to the electromagnetic drive. The output of the AND gate or equivalent circuit can then be output, for example, to the transistor coupled to the electromagnetic drive in such a way that the electromagnetic drive is controlled with the output signal or control signal via the transistor.

[0020] The circuit may include a microcontroller. The first PWM signal or the second PWM signal may be provided by the microcontroller. The first or second PWM signal may also be provided by a discrete circuit.

[0021] The circuit can be located in a positioner.

[0022] The positioner or position controller can be located on or in the solenoid valve.

[0023] A method for controlling an electromagnetic drive for a solenoid valve is also provided. Accordingly, a control signal for operating the electromagnetic drive is provided, wherein the control signal has a first time interval, an optional second time interval, and a third time interval, which advantageously follow one another directly in time. The first time interval has a first duty cycle, the second time interval has a second duty cycle, and the third time interval has a third duty cycle. The duty cycle in the first, second, and third time intervals is less than one, and the first duty cycle is greater than the second duty cycle, and the second duty cycle is greater than the third duty cycle.

[0024] The first time interval and the first duty cycle can be set such that the electromagnetic drive changes from a first operating state to a second operating state. The optional second time interval and the second duty cycle can be set such that the electromagnetic drive or the electromagnetic valve remains in the second operating state. The third time interval and the third duty cycle can be set such that the electromagnetic drive or the electromagnetic valve changes from the second operating state to the first operating state. A supply voltage level of a supply voltage of the electromagnetic drive is detected, and the first duty cycle and / or second duty cycle is set based on the detected supply voltage level. This ensures that the required time-averaged voltage is always applied to the electromagnetic drive.

[0025] The third duty cycle can be zero. In other words, the control signal can be off or remain low throughout the third interval.

[0026] The first operating state of the electromagnetic drive can be the closed operating state of the solenoid valve, and the second operating state can be the open operating state of the solenoid valve. In another embodiment, this can also apply vice versa. Advantageously, however, the first and second operating states relate to a complete opening or a complete closure of the valve. SHORT DESCRIPTION OF THE CHARACTERS

[0027] Further advantageous aspects and features of the invention will become clear from the following description of embodiments with reference to the attached figures, in which Fig. 1 a simplified schematic voltage-time diagram with three PWM signals, and Fig. 2 a simplified schematic voltage-time diagram with three PWM signals with temporally different duty cycles of individual signals, and Fig. 3 a simplified schematic diagram of a circuit for providing a control signal for an electromagnetic drive of a solenoid valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] Fig. 1 shows a simplified schematic voltage-time diagram with a first, a second and a third PWM signal (PWM signal) PWM1, PWM2, PWM3. The third PWM signal PWM3 serves as a control signal for controlling an electromagnetic drive of a solenoid valve in a first embodiment. The electromagnetic drive comprises a magnetic coil which is operated based on the control signal. The first PWM signal PWM1 serves as an operating variable with supply voltage adjustment and the second PWM signal PWM2 serves as a manipulated variable for the electromagnetic drive. The third PWM signal PWM3 is a combination of the first PWM signal PWM1 and the second PWM signal PWM2 created according to the principle of the AND operation. The level of the third PWM signal PWM3, orThe control signal for the electromagnetic drive is only high (ON level) when both the first PWM signal PWM1 and the second PWM signal PWM2 are simultaneously high. The control signal, or the third PWM signal PWM3, incorporates all the advantageous properties of the first and second PWM signals PWM1 and PWM2.

[0029] In the voltage-time diagram, time is plotted on the abscissa and voltage on the ordinate. The top signal is the first PWM signal PWM1. The time span between the times TOPWM1 and T1PWM1 is the period T1 of the first PWM signal PWM1. The period T1 comprises one complete cycle, i.e. the sum of the ON time and OFF time. The inverse of the period T1 is the fundamental frequency F1. The ON time T1ON corresponds to the time span between the times TOPWM1 and T01PWM1, and the OFF time T1OFF corresponds to the time span between the times T01PWM1 and T1PWM1. During the ON time T1ON, the PWM signal PWM1 is high, i.e. the amplitude or level is high. During the OFF time T1OFF, the PWM signal PWM1 is low, meaning its amplitude or level is low. The ratio of the ON time T1ON to the period T1 corresponds to the first duty cycle TV1.According to the present embodiment, TV1 is, for example, 50% in the case of the first PWM signal PWM1. The first PWM signal PWM1 provides an adequate time-averaged supply voltage for the solenoid coil.

[0030] The supply voltage for the solenoid coil can vary depending on the nominal supply voltage of a power supply unit and can also be subject to fluctuations during operation of the solenoid valve. The first duty cycle TV1 can be used to adapt the voltage of a supply voltage source to the required voltage across the solenoid coil. For example, using a duty cycle of 50%, an initial input voltage of 24 V can be reduced to an effective (time-averaged) input voltage of 12 V, which is applied to the solenoid coil. The reduced effective voltage Ueff across the solenoid coil reduces the current through the coil. The reduction in the effective applied voltage Ueff and the associated reduction in the applied current result in particular in a reduction in the electrical power required to operate the coil (reduction in power loss).The first duty cycle TV1 is always less than one, thus it has a finite OFF time T1OFF.

[0031] The inverse of the period T1 results in a first fundamental frequency F1 of the first PWM signal PWM1. The first duty cycle TV1 is selected such that sufficient power is provided for a transition from a first operating state to a second operating state of the electromagnetic drive. In this case, this is the change in position of an armature of the electromagnetic drive from a non-energized position to an energized position. If the armature is in the energized position, a process fluid flow (air flow), for example, can be provided. The electromagnetic valve can be in the open operating state. The electromagnetic drive is then in the second operating state.

[0032] The second PWM signal PWM2 represents the control variable for the electromagnetic actuator. This control variable determines the position of the armature and thus whether a process fluid flow (air flow) is provided. The second PWM signal PWM2 can generally have a longer period T2 than the first PWM signal PWM1 and thus a lower fundamental frequency F2 than the first PWM signal PWM1.

[0033] Regardless of the ratio of the fundamental frequencies F1 and F2, the second PWM signal PWM2 can also be defined such that at least the OFF time(s) of the second PWM signal PWM2 is (are) longer than the OFF times of the first PWM signal PWM1. In addition, both the ON time(s) T2ON and the OFF time(s) T2OFF can advantageously be longer than the ON time(s) and OFF time(s) of the first PWM signal PWM1. The second fundamental frequency F2 and a duty cycle of the second PWM signal PWM2 or the ON time T2ON and the OFF time T2OFF are selected such that the armature can, on the one hand, change from the non-attracted position to the attracted position during the ON time T2ON and, if necessary, remain in the attracted position, and, on the other hand, change back to the non-attracted position during a sufficiently long OFF time T2OFF. In the non-energized position of the armature, the solenoid valve is in the closed operating state.The electromagnetic drive is in the first operating state. Due to the longer OFF time T2OFF of the second PWM signal PWM2 required for the armature to change to the non-energized position, the second fundamental frequency F2 can be lower than the first fundamental frequency F1 of the first PWM signal PWM1. The duty cycle of the second PWM signal PWM2 can always be less than one. In principle, the OFF time T2OFF is selected so that the electromagnetic valve can change from the second operating state (e.g. open) to the first operating state (closed). In addition, the ON time T2ON is selected so that the electromagnetic valve can change from the first operating state (e.g. closed) to the second operating state (e.g. open) and, if necessary, can also remain in this second operating state.

[0034] The third PWM signal PWM3 is the control signal for the electromagnetic drive and is formed by combining the first PWM signal PWM1 as the first signal component S1 and the second PWM signal PWM2 as the second signal component S2, using a logical AND operation. The third PWM signal PWM3 comprises at least two relevant time intervals, which, for reasons of consistency, are referred to as the first time interval IV1 and the third time interval IV3. Accordingly, the first time interval IV1 has a first duty cycle TV1, and the third time interval IV3 has a third duty cycle TV3.

[0035] The third PWM signal PWM3 has a third fundamental frequency F3, which corresponds to the first fundamental frequency F1. In the third PWM signal PWM3, the duty cycle can change over time.

[0036] In the first time interval IV1, the duty cycle corresponds to the first duty cycle TV1. In the third time interval IV3, there is no ON time, and the third duty cycle TV3 has a value of zero. The duration of the third time interval IV3 corresponds to the OFF time T2OFF of the second PWM signal PWM2 or is determined by it.

[0037] During the ON time T3ON of the third PWM signal PWM3, the solenoid coil is supplied with a voltage, whereas during the OFF times T3OFF1, T3OFF2, no voltage is applied to the solenoid coil.

[0038] In the first time interval IV1, the electromagnetic actuator changes from the first to the second operating state and remains in the second operating state. This provides, for example, a process fluid flow (air flow), and the solenoid valve is in the open operating state. In the third time interval IV3, the electromagnetic actuator changes from the second operating state to the first operating state and remains in the first operating state. This closes the solenoid valve. The OFF time T3OFF2 of the third PWM signal PWM3 is long enough to ensure that the electromagnetic actuator can change from the second to the first operating state.

[0039] Fig. 2 shows a simplified schematic voltage-time diagram with a first, a second and a third PWM signal PWM1, PWM2, PWM3 in a second embodiment.

[0040] In the first PWM signal PWM1, the duty cycle in the signal waveform changes from an initial first duty cycle TV11 of, for example, 50% to a changed duty cycle TV12 of 20%. By reducing the duty cycle in the signal waveform, the effective (time-averaged) voltage applied across the solenoid coil is reduced, which is why the current through the coil drops. This can reduce the power loss. After the armature changes from the non-energized position to the attracted position, the duty cycle is reduced such that the power is sufficient to hold the armature in the attracted position. This corresponds to the second operating state of the electromagnetic drive, in which the solenoid valve is in the open operating state. To hold the armature in the attracted position, less power is required than to move it from the non-energized to the attracted position.

[0041] The third PWM signal PWM3 also represents the control signal here and, with the additional power reduction in the signal curve, comprises three time intervals, namely a first time interval IV1 with a first duty cycle TV1, a second time interval IV2 with a second duty cycle TV2 and a third time interval IV3 with a third duty cycle TV3.

[0042] The control signal, or the third PWM signal PWM3, has a third fundamental frequency F3, which corresponds to the first fundamental frequency F1. The first, second, and third duty cycles of the PWM signal PWM3 assume three values: TV1, TV2, and TV3. In the first time interval IV1, the first duty cycle TV1 of the PWM signal PWM3 corresponds to the initial duty cycle TV11 of the first PWM signal PWM1 before the power reduction. The fundamental frequency F3 and the duty cycle TV1 are high enough to move the armature from the first position to the second position. Thus, the electromagnetic actuator changes from the first to the second operating state and remains in the second operating state. The solenoid valve is opened.

[0043] In the second time interval IV2, the second duty cycle TV2 of the PWM signal PWM3 corresponds to the reduced duty cycle TV12 of the first PWM signal PWM1 after the power reduction. The fundamental frequency F3 and the second duty cycle TV2 are high enough to keep the armature in the second, or attracted, position. Thus, the electromagnetic actuator remains in the second operating state. The solenoid valve remains open.

[0044] The third time interval IV3 has no ON time and thus a duty cycle of zero. In the third time interval IV3, the electromagnetic actuator returns from the second to the first operating state. The solenoid valve closes. The duty cycle decreases from the first to the third time interval (TV1 > TV2 > TV3) and is always less than one (TV1, TV2, TV3 < 1).

[0045] Fig.3 shows a simplified schematic diagram of an electronic circuit or a circuit 100 for an electromagnetic drive of a solenoid valve (not shown). For simplicity, only the solenoid coil 110 of an electromagnetic drive of a valve is shown. The circuit is located in the positioner 170. The positioner 170 can be accommodated in a housing with one or more solenoid valves. The positioner can be attached to the side of the electromagnetic drive or placed on top of it. The solenoid coil 110 moves the armature (not shown) depending on the applied current to open and close the solenoid valve. The solenoid coil 110 is coupled to a supply voltage source 120. To determine the voltage VS of the supply voltage source 120, this is connected to an electronic signal processing unit 140, e.g.a microcontroller. The signal processing unit 140, also embodied as a discrete circuit or a microcontroller, is supplied with the actual value VS of the supply voltage as an analog signal and converted into a digital signal, for example in an integrated analog-to-digital converter 141. Based on the measured actual value of the voltage VS, the signal processing unit or the microcontroller 140 provides the first PWM signal PWM1 at a first output 142. Based on the measured voltage VS, the signal processing unit or the microcontroller 140 determines the first duty cycle TV1 of the first PWM signal PWM1 and / or the second duty cycle TV2 of the first PWM signal PWM1 for an effective voltage level to be applied to the magnetic coil 110. The signal processing unit or the microcontroller 140 also provides the second PWM signal PWM2 at a second output 143.The second PWM signal PWM2 forms the control variable for the electromagnetic drive. The second PWM signal PWM2 can be determined based on an external signal provided to the signal processing unit or microcontroller 140.

[0046] In one embodiment, the first and / or second PWM signals PWM1, PWM2 can also be provided by discrete circuits.

[0047] The two outputs 142, 142 of the signal processing unit or microcontroller 140 are connected to a first and second input 151, 152 of an AND gate 150. The AND gate 150 can, for example, be an integrated circuit. In the AND gate 150, the first PWM signal PWM1 and the second PWM signal PWM2 are linked to each other via a logical AND. The output 153 of the AND gate 150 provides a third PWM signal PWM3. The third PWM signal PWM3 is the control signal for the electromagnetic drive of the valve or for the solenoid coil 110 of the electromagnetic drive. The output 153 of the AND gate 150 is coupled to a transistor 160 or connected to a transistor 160. The transistor 160 is coupled to the solenoid coil 110. In this case, the channel of the transistor is coupled between the solenoid coil 110 and ground.When the transistor is turned on, current can flow through the solenoid coil 110, and the electric drive of the solenoid valve can change its operating state. In this example, transistor 160 is an NPN bipolar transistor with its collector coupled to the coil and its emitter coupled to ground. Of course, other transistor types are also possible.

[0048] Transistor 160 is switched on and off by the third PWM signal PWM3, thereby controlling the current flow through the solenoid coil 110. This ensures that the solenoid coil 110 is advantageously controlled by the control signal or PWM signal PWM3 with regard to the current supply voltage level, power reduction, and valve position.

Claims

[1] Circuit (100) for electronic control of an electromagnetic actuator of an electromagnetic valve, wherein the circuit (100) is configured to provide a control signal for the electromagnetic actuator, which has a high level and a low level, and the control signal has at least a first time interval (IV1) with a first duty cycle (TV1), an optional second time interval (IV2) with a second duty cycle (TV2), and a third time interval (IV1) with a third duty cycle (TV3), wherein the first, second, and third duty cycles (TV1, TV2, TV3) are less than one, and the first duty cycle (TV1) is greater than the second duty cycle (TV2), and the second duty cycle (TV2) is greater than the third duty cycle (TV3), and the time length of the time intervals and the magnitude of the duty cycles are configured such thatthat the electromagnetic drive changes from a first operating state to a second operating state in the first time interval (IV1), optionally remains in the second operating state in the second time interval (IV2) and changes from the second operating state to the first operating state in the third time interval (IV3), wherein the circuit (100) is configured to detect a supply voltage level of a supply voltage (VS) for the electromagnetic drive and to adjust one, several or all duty cycles (TV1, TV2, TV3) of the control signal based on the detected supply voltage level, and wherein the circuit (100) is configured to provide the control signal according to a logical AND operation of a first pulse-width modulated (PWM) signal (PWM1) and a second pulse-width modulated (PWM) signal (PWM2), wherein a level of the control signal is only at a high level if both the first pulse-width modulated (PWM) signal (PWM1) and the second pulse-width modulated (PWM) signal (PWM2) are simultaneously at a high level. [2] Circuit (100) according to claim 1, wherein the first PWM signal (PWM1) is configured to provide the first time interval (IV1) with the first duty cycle (TV1) and in particular to provide the second time interval (IV2) with the second duty cycle (TV2). [3] Circuit (100) according to claim 1 or 2, wherein the second PWM signal (PWM2) is configured to provide the third time interval (IV3) with the third duty cycle (TV3). [4] Circuit (100) according to any one of claims 1 to 3, wherein the circuit comprises an AND gate (150) configured to combine the first PWM signal (PWM1) and the second PWM signal (PWM2) according to a logical AND operation to form the control signal. [5] Circuit (100) according to claim 4, wherein it comprises a transistor (160) which is coupled to the electromagnetic drive and receives the control signal from the AND gate (150) to control the electromagnetic drive with the control signal. [6] Circuit (100) according to any one of claims 1 to 5, wherein the circuit comprises a signal processing unit (140), in particular a microcontroller, which is configured to provide the first PWM signal (PWM1). [7] Circuit (100) according to claim 6, wherein the signal processing unit comprises a first discrete circuit and / or a second discrete circuit configured to provide the first PWM signal (PWM1) and / or second PWM signal (PWM2). [8] Circuit(100) according to claim 1, wherein it is located in a position controller or positioner. [9] A method for controlling an electromagnetic actuator for a solenoid valve comprising: providing a control signal for operating the electromagnetic actuator, wherein the control signal has a first time interval (IV1), an optional second time interval (IV2) and a third time interval (IV3) which follow each other immediately in time, wherein the first time interval (IV1) has a first duty cycle (TV1), the optional second time interval (IV2) has a second duty cycle (TV2) and the third time interval (IV3) has a third duty cycle (TV3), wherein the duty cycle in the first, second and third time intervals (IV1, IV2, IV3) is less than one, and the first duty cycle (TV1) is greater than the second duty cycle (TV2) and the second duty cycle (TV2) is greater than the third duty cycle (TV3),wherein the control signal is provided according to a logical AND operation of a first pulse-width modulated (PWM) signal (PWM1) and a second pulse-width modulated (PWM) signal (PWM2), wherein a level of the control signal is high only when both the first pulse-width modulated (PWM) signal (PWM1) and the second pulse-width modulated (PWM) signal (PWM2) are simultaneously high, and the method further comprises: setting the first time interval (IV1) and the first duty cycle (TV1) such that the electromagnetic drive switches from a first operating state to a second operating state, optionally setting the second time interval (IV2) and the second duty cycle (TV2) such that the electromagnetic drive remains in the second operating state, and setting the third time interval (IV3) and third duty cycle (TV3) such thatthat the electromagnetic drive switches from the second operating state to the first operating state, the method further comprising: Detect a supply voltage level of a supply voltage (VS) of the electromagnetic drive and set the first duty cycle (TV1) and / or the second duty cycle (TV2) based on the detected supply voltage level. [10] Method according to claim 9, wherein the third time interval (IV3) has a duty cycle of zero. [11] Method according to claim 9 or 10, wherein the first operating state of the electromagnetic actuator is the closed operating state of the solenoid valve and the second operating state is the open operating state of the solenoid valve.

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