Method for controlling a bistable electromagnetic actuator

Abstract

The invention relates to a method for controlling a bistable electromagnetic actuator, comprising the following steps: upon receiving a command to transition between two stable positions of the actuator, subjecting a magnet coil of the actuator to a first voltage (Ve) capable of moving a core of the actuator and monitoring a current (I1, I2) passing through the magnet coil, and when the current in the magnet coil crosses a threshold value (ILM1, -ILM2), switching off the magnet coil, the threshold value being greater, in absolute value, than a minimum value (ISM1, ISM2) of current to be supplied to the magnet in order to move the core.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for controlling a bistable electromagnetic actuator

[0003] technical field

[0004] The present invention relates to the field of bistable electromagnetic actuators used in particular in aircraft, for example to control a hydraulic valve of an aircraft braking system.

[0005] State of the art

[0006] A typical electromagnetic actuator consists of an electromagnet with a coil and a movable ferromagnetic core inside the coil. In a bistable electromagnetic actuator, the core has two stable positions, for example, a retracted position and an extended position. Unlike conventional actuators, a bistable actuator does not require power to maintain itself in either of these two stable positions, and therefore only consumes energy to change state.

[0007] Such actuators are used in hydraulic valves, particularly in aircraft braking systems. Some of these systems include a normal braking system, an emergency braking system that supplements the normal braking system in case of failure, and a parking brake system to keep the aircraft stationary. The emergency braking system provides brake pressure that varies according to a pilot command. The parking brake system maintains brake pressure when the aircraft is stationary and during a complete power outage. The use of a hydraulic valve with a bistable electromagnetic actuator is desirable to simultaneously provide the parking brake function when all power is cut off.It is also desirable to be able to use such a bistable actuator in high-frequency switched control mode to adjust the braking pressure according to a pilot command.

[0008] The control of the electromagnet in a bistable electromagnetic actuator is based on a voltage or current supply via a fixed-duration time delay or a signal from an external sensor. The external sensor is designed to signal the actuator's end of travel or indicate actuator movement, for example, by providing a pressure measurement in the case of a hydraulic valve. Implementing a fixed-duration time delay requires relatively large margins in the timing duration. This is because it is essential to ensure that, under all environmental conditions (ambient temperature, fluid temperature in the case of a solenoid valve, supply voltage, wear, etc.), the actuator's moving core has enough time to transition between its two stable positions, for example, extended and unextended.The result is that this fixed time delay can have a significant duration that cannot be adjusted to a reduced value that is just necessary, which poses a problem of consumption.

[0009] Furthermore, implementing a limit switch or pressure sensor raises issues, particularly regarding integration within the actuator. Adding an external sensor (to the valve assembly) also leads to increased cost and weight, not only due to the sensor itself but also to the necessary external equipment, such as a connector and wiring harness, as well as electronic power supply and electromagnetic interference filtering components. This equipment also negatively impacts the overall reliability. While these drawbacks persist, they are less pronounced when integrating the sensor into the valve assembly.

[0010] On the other hand, when the actuator is controlled by alternating high-frequency commands, for example by PWM (Pulse-Width Modulation), the electromagnet is subjected to a quasi-continuous power supply. However, bistable actuators are rarely thermally designed to withstand such a quasi-continuous power supply or a high activation frequency.

[0011] Furthermore, the activation force that determines the sizing of an electromagnet is a compromise between a high number of turns and a higher inrush current. However, the inrush current requires a low coil resistance and must therefore be regulated or limited in the case of voltage control, otherwise the current capacity of the system incorporating the actuator (for example, an aircraft circuit breaker) may be exceeded or excessively rapid heating may occur.

[0012] It is therefore desirable to provide a control method for a bistable-type electromagnetic actuator with relatively low power consumption and whose control does not require an external sensor. Summary

[0013] Embodiments relate to a method of controlling a bistable electromagnetic actuator comprising steps of: upon receiving a transition command between two stable positions of the actuator, subjecting an electromagnet coil of the actuator to a first voltage capable of moving a core of the actuator and monitoring a current flowing through the electromagnet coil, and when the current in the electromagnet coil crosses a threshold value greater in absolute value than a minimum current value to be supplied to the electromagnet to move the core, placing the electromagnet coil off, wherein the threshold value in absolute value is set at less than 20% above the minimum current value to be supplied to the electromagnet to move the core, or at less than 20% below a maximum static current value reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage.

[0014] Thanks to these features, the actuator incorporating such an electromagnet exhibits reduced power consumption and, consequently, reduced heat generation. The electromagnet's switching times are also reduced. It can therefore be controlled at high frequencies, as in the braking systems of certain aircraft to adjust braking pressure. Furthermore, the electromagnet is controlled without any external sensors.

[0015] According to one embodiment, the absolute value of the threshold is set at less than 10% above the minimum current value to be supplied to the electromagnet to move the core, or at less than 10% below a maximum static current value reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage.

[0016] Defining such a threshold makes it possible to limit the energy required to actuation the core in the electromagnet to the bare minimum.

[0017] According to one embodiment, the threshold value depends on a polarity of the first voltage, and in which: when the first voltage has a positive polarity, the threshold value is set at less than 10% above a first minimum value of current to be supplied to the electromagnet to move the core, or at less than 10% below a first maximum value of static current reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage, and when the first voltage has a negative polarity, the threshold value is set at less than 10% below a second maximum value of current to be supplied to the electromagnet to move the core, or at less than 10% above a second minimum value of static current reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage.

[0018] Defining such thresholds makes it possible to limit the energy required to actuation the core in the electromagnet to the bare minimum.

[0019] According to one embodiment, the threshold value in absolute value is fixed at the minimum current value to be supplied to the electromagnet to move the core, to which is added a margin determined according to parameters of extreme external environmental conditions of the actuator.

[0020] Defining such a threshold makes it possible to limit the energy required to actuation the core in the electromagnet to the bare minimum.

[0021] According to one embodiment, the command is received in the form of a change of state of a two-state control signal, the state of the control signal determining a polarity of the first voltage to which the electromagnet coil is subjected.

[0022] Thus, the electromagnet can be controlled from a simple two-state logic signal.

[0023] According to one embodiment, the command is received in the form of a polarity reversal of a supply voltage corresponding to the first voltage to which the electromagnet coil is subjected.

[0024] Thus, the control of the electromagnet can be achieved simply by reversing the polarity of the voltage previously applied to the coil of the electromagnet.

[0025] Embodiments may also relate to a bistable electromagnetic actuator comprising: an electromagnet coil, a moving core actuated by the electromagnet, and an electromagnet control circuit configured to implement the process as previously defined.

[0026] Embodiments may also relate to a solenoid valve controlled by such an actuator.

[0027] Embodiments may also relate to an aircraft braking system, including such a solenoid valve.

[0028] Embodiments may also relate to an aircraft comprising such a braking system.

[0029] Brief description of the figures

[0030] The present invention will be better understood with the aid of the following description of exemplary embodiments with reference to the accompanying figures, in which identical reference symbols correspond to structurally and / or functionally identical or similar elements.

[0031] [Fig 1] Figure 1 schematically represents a control circuit for a bistable electromagnetic actuator, according to one embodiment,

[0032] [Fig 2] Figure 2 shows timing diagrams of signals present in the actuator control circuit, according to one embodiment,

[0033] [Fig 3] Figure 3 schematically represents a control circuit for the actuator control circuit, according to one embodiment,

[0034] [Fig 4] Figure 4 shows timing diagrams of signals present in the actuator control circuit, according to another embodiment,

[0035] [Fig 5] Figure 5 schematically represents a control circuit of a bistable electromagnetic actuator, according to another embodiment.

[0036] [Fig 6] Figure 6 schematically represents a control circuit for the actuator control circuit, according to another embodiment,

[0037] [Fig 7] Figures 7A, 7B schematically represent in longitudinal section an example of a classic bistable solenoid valve, respectively in closed position and in open position.

[0038] Detailed description

[0039] Figure 1 shows an EMC control circuit for a bistable electromagnetic actuator, according to one embodiment. The EMC control circuit comprises an H-bridge and a CTL control circuit for the H-bridge. The H-bridge includes four switches S1, S2, S3, and S4. Switch S1 is connected to switches S2 and S3 and to a first terminal B3 of a coil CL of the actuator. Switch S4 is connected to switches S2 and S3 and to a second terminal B4 of the coil CL. The H-bridge is subjected to a supply voltage Vs applied between a terminal B1 at the junction of switches S1 and S3 and a terminal B2 at the junction of switches S2 and S4. In Figure 1, Ve denotes the voltage across the coil CL, I1 the current through the coil, and I2 the current through the H-bridge between the terminals B1 and B2 where the supply voltage Vs is applied.Each of the switches S1-S4 is an electronic switch, for example made by a transistor.

[0040] Thus, the control of switches S1-S4 activates the electromagnet and moves a PL core within the electromagnet between two stable positions: an extended position and a retracted position. Bistable electromagnets are bipolarly controlled by voltage or current. The control circuit CTL is configured to receive a COM control signal and a current measurement signal I1 or I2, and to control switches S1-S4 based on these signals. In one embodiment, the control circuit CTL is configured to open all switches S1-S4 when the current I1 or I2 reaches a negative threshold value ILM2 or a positive threshold value ILM1.

[0041] The operation of the CTL control circuit is illustrated by the timing diagrams of the COM control signal, the current measurement signal 11 or I2, and the voltage Ve shown in Figure 2, and by Table 1 below, indicating the state (O: open, F: closed) of the switches S1-S4 as a function of time t and the state of the COM control.

[0042] Table 1

[0043] At time t0, the control signal COM is high, and all switches S1-S4 are open. Therefore, the voltage Ve and the current I1 or I2 are negative. At time t1, the control circuit CTL closes switches S2 and S3 to activate the electromagnet and thus move the core PL, for example, into the deployed position, while switches S1 and S4 remain open. From time t1, the voltage Ve decreases to -Vs, and the current I1 or I2 decreases (increases in absolute value) to a value of -ISM2, producing a sufficiently high magnetic force in the electromagnet's coil CL to move the core PL within the coil CL at time t2. This movement generates a back electromotive force, which causes the current to increase (decrease in absolute value) between time t2 and time t3.Then, the current 11 or I2 decreases again (increases in absolute value) between time t3 and time t4 until the negative threshold value -ILM2 (ISM2 and ILM2 represent positive values).

[0044] At time t4, all switches S1-S4 are open when the measured current I1 or I2 reaches the threshold value -ILM2. The voltage Ve then drops to 0 and the current I1 or I2 falls (in absolute value) to 0. At time t5, the control circuit CTL closes switches S1 and S4 to activate the electromagnet and move the core PL, for example, into the retracted position, while switches S2 and S3 remain open. The voltage Ve then changes to the voltage Vs. From time t5 onward, the shape of the current signal I1 or I2 is symmetrical to that observed between times t1 and t4. Thus, from time t5, the current I1 or I2 increases until it reaches a value ISM1 where the magnetic force produced in the coil CL is high enough to move the core PL within the coil. This displacement implies a back electromotive voltage which causes the current 11 or I2 to drop between instants t6 and t7.From time t7, the current I1 or I2 increases again until it reaches the positive threshold value ILM1 at time t8. At time t8, all switches S1-S4 are open when the current I1 or I2 reaches the threshold value ILM1. From time t8, the voltage Ve in the coil CL drops to 0, while the current I1 or I2 falls towards 0.

[0045] Thanks to these features, the energy required to actuate the core in the electromagnet can be adjusted to the bare minimum by simply setting a threshold value. As a result, the actuator incorporating such an electromagnet can exhibit reduced power consumption and, consequently, reduced heat generation. With reduced switching times for the electromagnet, it can be controlled at high frequencies, as in the braking systems of some aircraft. Furthermore, the electromagnet is controlled without any external sensors.

[0046] In one embodiment, the negative threshold value -ILM2 is set a few percent higher (for example, less than 10%, or between 3% and 8%) than a static current value -IST2 (or the absolute maximum) reached in the coil CL when it remains subjected to the voltage -Vs. The maximum value -IST2 can be equal to the supply voltage -Vs divided by the internal resistance Rc of the coil CL in a static state. Similarly, the positive threshold value ILM1 is set a few percent lower (for example, less than 10%, or between 3% and 8%) than the static current value IST1 reached in the coil CL when it remains subjected to the voltage Vs.

[0047] In another embodiment, the negative threshold value -ILM2 is set a few percent lower (for example, less than 10%, or between 3% and 8%) than the current value -ISM2 at which the PL core in the CL coil begins to move (towards its extended position). Similarly, the positive threshold value ILM1 is set a few percent higher (for example, less than 10%, or between 3% and 8%) than the current value ISM1 at which the PL core in the CL coil begins to move (towards its retracted position). According to another embodiment, the negative threshold value in absolute value ILM2 and the positive threshold value ILM1 are equal and fixed at a few percent (for example less than 10%, or between 3% and 8%), below the maximum static current value 1ST1 or IST2, or above the current value ISM1 or ISM2.

[0048] In one embodiment, the supply voltage VS or Ve of the electromagnet's coil CL is increased to reduce the electromagnet's response times (between times t1 and t2, and between times t5 and t6) following the application of a deployment or retraction command (at time t1 or t5). Indeed, the threshold values ​​ILM1 and ILM2 do not depend on the supply voltage Vs or Ve of the electromagnet's coil CL. Consequently, the power seen by the electromagnet varies little with the supply voltage.

[0049] According to one embodiment, the current threshold value ILM1, ILM2 is determined by the force required to move the core within the electromagnet, plus a margin of a few percent determined based on parameters of extreme external environmental conditions (particularly ambient temperature) which influence the current threshold values ​​ILM1, ILM2. Indeed, the movement of the core may require more or less energy depending on the ambient temperature.

[0050] The CTL control circuit can be implemented simply using an electronic circuit without requiring computational processing. Figure 3 illustrates an example of such a CTL control circuit. The CTL control circuit comprises a comparator CP1, an EDT circuit for rising or falling edge detection in a signal, an RS-type flip-flop FF1, an inverter-type logic gate IG1, and two AND-type logic gates AG1 and AG2. The COM control signal is supplied to the inputs of the EDT circuit, the AG2 gate, and the inverter IG1. The output of the inverter IG1 is connected to an input of the AG1 gate. The comparator CP1 receives the current measurement signal I1 (in absolute value) or I2 on an inverting input, and the threshold value ILM1 or ILM2 on a forward input. The flip-flop FF1 receives the output signal from the EDT circuit on an input S and the output signal from the comparator CP1 on an input R.A direct output Q of the flip-flop FF1 is connected to an input of gate AG1 and an input of gate AG2. Gate AG1 provides the control signal for switches S2 and S3 and gate AG2 provides the control signal for switches S1 and S4.

[0051] According to one embodiment, the actuator is controlled by alternating high-frequency commands, for example by PWM, in particular to obtain an adjusted flow rate in a solenoid valve. Thus, as illustrated in Figure 4, the instant t4 as described with reference to Figure 2 is followed by an instant t5' when the COM control signal transitions from state 0 to state 1, close to instant t4, that is, before the current 11 or I2 reaches 0 A. Between instant t5' and an instant t6', the current 11 or I2 follows a variation similar to that observed between instants t5 and t8 in Figure 2. The COM control signal can be inverted by transitioning to state 0 at an instant t7' just after instant t6', that is, before the current 11 or I2 reaches 0 A. Between instant t7' and an instant t8', the current 11 or I2 follows a variation similar to that observed between instants t1 and t4.Thus, the COM control signal can have pulses that can be reduced to the duration between times t5 and t8 and intervals between these pulses that can be reduced to the duration between times t1 to t4.

[0052] Furthermore, a change of state in the COM signal could occur as soon as the PL core switches to the other position (deployed / retracted), i.e., after time t2 or time t6. Such a change of state triggers the reversal of the polarity of the voltage Ve by appropriate control of switches S1 to S4, causing the start of a sequence beginning at time t1 or t5 depending on the transition observed in the COM control signal.

[0053] Figure 5 shows an alternative embodiment of the electromagnet control circuit EMC1. The EMC1 control circuit comprises two switches S11 and S12, two diodes D1 and D2 connected in parallel with switches S11 and S12 respectively, a bidirectional freewheeling diode D3 connected in parallel with the electromagnet's coil CL, a control circuit CTL1 for switches S11 and S12, and a voltage generation circuit VGN that provides a supply voltage Vs to the coil CL. The cathodes of diode D1 and diode D2 are connected to terminals B13 and B14 of the coil CL, respectively. The anode of diode D1 and switch S11 are connected to the first terminal B11 of the voltage generation circuit VGN. The anode of diode D2 and switch S12 are connected to the second terminal B12 of the VGN circuit. The voltage Vs is supplied between the first and second terminals of the VGN circuit.The freewheeling diode D3 prevents voltage spikes when switches S11 and S12 are opened. The EMC1 control circuit receives a current measurement signal of I2 or I3 flowing in the electromagnet's CL coil from a current probe IS1 or IS2 connected to terminal B11 or B12 of the VGN circuit, or from two current probes IS1 and IS2 connected to terminals B11 and B12 of the VGN circuit, respectively. The VGN voltage generation circuit is configured so that the supplied voltage Vs is positive or negative to trigger the deployment and retraction positions of the PL core actuated by the electromagnet, respectively. The CTL1 control circuit is configured to close switch S11 and open switch S12 when the voltage Vs is positive, and conversely, to open switch S11 and close switch S12 when the voltage Vs is negative.In addition, the CTL1 control circuit is configured to open switches S11 and S12 when the current 11 in coil CL reaches the threshold value ILM1 or ILM2.

[0054] Table 2 below shows the state (O: open, F: closed) of switches S11, S12 and the state (B: blocked, P: conducting) of diodes D1, D2, as a function of time t and the polarity of the output voltage Vs of the VGN circuit, in relation to the current timing diagram in Figure 2.

[0055] Table 2

[0056] When the voltage generation circuit VGN provides a positive voltage +Vs representing a command to the deployed position of the PL core in the electromagnet, the control circuit CTL1 closes switch S11. Current then flows through diode D2. The voltage Ve in coil CL is equal to Vs. When the current in coil CL reaches the threshold value ILM2, the control circuit CTL1 opens switch S11.

[0057] When the voltage generation circuit VGN provides a negative voltage -Vs, representing a command to retract the PL core in the electromagnet, the control circuit CTL1 closes switch S12. Current then flows through diode D1. The voltage Ve in coil CL is equal to -Vs. When the current in coil CL reaches the threshold value ILM1, the control circuit CTL1 opens switch S12.

[0058] Thus, the EMC1 control circuit controls the current 11 in the CL coil according to the current timing diagram 11 or I2 in Figure 2, the COM control signal being replaced by the voltage control Vs provided by the VGN voltage generation circuit. The definition of the threshold values ​​ILM1, ILM2 can be the same as in the embodiment of Figure 1.

[0059] When switches S11 and S12 are each made by a transistor, diodes D1 and D2 can be part of these transistors.

[0060] The CTL1 control circuit can also be implemented simply using an electronic circuit without computational capabilities. Figure 6 shows an example of such an implementation. The CTL1 control circuit includes two comparators, CP2 and CP3; a polarity detection PDT circuit to detect the polarity of the voltage Vs supplied by the generator VGN; an RS-type flip-flop, FF2; an inverter-type logic gate, IG2; and two AND-type logic gates, AG3 and AG4. The voltage Vs generated by the VGN circuit is supplied to the input of the PDT circuit and to the direct input of comparator CP3, whose inverting input is connected to ground. The output signal of comparator CP3 is supplied to the input of gate AG4 and inverter IG2. The output of inverter IG2 is connected to an input of gate AG3.Comparator CP2 receives the current measurement signal I1 (absolute value) or I2 (or I3) on an inverting input, and the threshold value ILM1 or ILM2 on a forward input. Flip-flop FF2 receives the output signal from the PDT circuit on an input S and the output signal from comparator CP2 on an input R. A forward output Q of flip-flop FF2 is connected to an input of gate AG3 and an input of gate AG4. Gate AG3 provides the control signal for switch S12, and gate AG4 provides the control signal for switch S1.

[0061] Figures 7A and 7B illustrate a classic example of a bistable solenoid valve. The solenoid valve comprises a body BY with an axial channel CH that can be hermetically sealed by a shutter OB in cooperation with a seal TJ. The solenoid valve includes a bistable electromagnetic actuator mechanically coupled to the shutter OB to position the latter either in a closed position, as shown in Figure 7A, or in an open position, as shown in Figure 7B. The actuator comprises an electromagnet and a ferromagnetic core PL, integral with the shutter OB. The electromagnet comprises one or more coils CL1, CL2, and optionally one or more permanent magnets PM1, PM2. The coils CL1, CL2 surround the core PL and the permanent magnets PM. The core PL is movable between two stable positions where it can abut against damping blocks DB.The two stable positions of the PL core correspond to the open and closed positions of the OB shutter. The entire CH channel assembly, including the OB shutter, the CL1 and CL2 coils, the PM1 and PM2 permanent magnets, and the DB blocks, can generally have a cylindrical shape. The PM1 and PM2 permanent magnets maintain the PL core in its two stable positions, particularly when the CL1 and CL2 coils are not energized.

[0062] It will be readily apparent to those skilled in the art that the present invention is susceptible to various embodiments and applications. In particular, the invention is not limited to the previously described examples of electromagnet control circuits. Indeed, other control circuits can easily be developed to control the electromagnet based on an external command and by comparing the current flowing in the electromagnet coil to the threshold values ​​described previously.

[0063] Furthermore, the actuator described above can be used in devices other than solenoid valves. Such an actuator can be used, for example, in an electronic lock or, more generally, a locking system, or even in electrical switching devices such as relays and circuit breakers.

[0064] Furthermore, the invention is not limited to solenoid valves used in aircraft braking systems. Such a solenoid valve can be used in other systems, such as medical systems or more generally in air or water flow control systems.

Claims

DEMANDS 1. A method for controlling a bistable electromagnetic actuator comprising the steps of: upon receiving a transition command (COM, Vs) between two stable positions of the actuator, applying a first voltage (Ve) to an electromagnet coil (CL, CL1, CL2) of the actuator capable of moving a core (PL) of the actuator and monitoring a current (I1, I2, I3) flowing through the electromagnet coil; and when the current in the electromagnet coil crosses a threshold value (ILM1, -ILM2) greater in absolute value than a minimum value (ISM1, -ISM2) of current to be supplied to the electromagnet to move the core, de-energizing the electromagnet coil, wherein the absolute threshold value (ILM1, ILM2) is set to less than 20% above the minimum value (ISM1, ISM2) of current to be supplied to the electromagnet to move the core. kernel, or less than 20% below a maximum value (IST1,IST2) of static current reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage.

2. Method according to claim 1, wherein the absolute threshold value (ILM1, ILM2) is set at less than 10% above the minimum value (ISM1, ISM2) of current to be supplied to the electromagnet to move the core, or at less than 10% below a maximum value (IST1, IST2) of static current reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage.

3. A method according to claim 1 or 2, wherein the threshold value (ILM1, -ILM2) depends on the polarity of the first voltage (Ve), and wherein: when the first voltage has a positive polarity, the threshold value (ILM1) is set at less than 10% above a first minimum value (ISM1) of the current to be supplied to the electromagnet to move the core, or at less than 10% below a first maximum value (IST1) of the static current reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage; and when the first voltage has a negative polarity, the threshold value (-ILM2) is set at less than 10% below a second maximum value (-ISM2) of the current to be supplied to the electromagnet to move the core, or at less than 10% above a second minimum value (-IST2) of the static current reached in the electromagnet coil when the electromagnet coil is subjected to the first voltage.

4. A method according to any one of claims 1 to 3, wherein the absolute threshold value (ILM1, ILM2) is fixed at the minimum value (ISM1, ISM2) of current to be supplied to the electromagnet to move the core, plus a margin determined according to parameters of extreme external environmental conditions of the actuator.

5. A method according to any one of claims 1 to 4, wherein the command is received in the form of a change of state of a two-state control signal (COM), the state of the control signal determining a polarity of the first voltage (Ve) to which the electromagnet coil is subjected.

6. A method according to any one of claims 1 to 4, wherein the command is received in the form of a polarity reversal of a supply voltage (Vs) corresponding to the first voltage (Ve) to which the electromagnet coil is subjected.

7. Bistable electromagnetic actuator comprising: an electromagnet having a coil and a moving core actuated by the electromagnet, and an electromagnet control circuit configured to implement the method according to any one of claims 1 to 6.

8. Solenoid valve controlled by an actuator according to claim 7.

9. Aircraft braking system, comprising a solenoid valve according to claim 8.

10. Aircraft comprising a braking system according to claim 9.

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