EP2019396A1 - Electromagnetic actuator with at least two coils - Google Patents

Abstract

The actuator has recall and maintaining units (21, 23B), an electrical current regulation unit (22) and a control subunit (24) for controlling voltage provided to windings (L1, L2) during actuator closing operation, and for controlling a winding switching unit (10) to place the windings in parallel mode to generate recall magnetic flow to close the actuator. The units and the subunit control current provided to the windings during maintenance operations of the actuator in close position, and control the unit (10) to place the windings in serial mode to generate maintenance magnetic flow. The windings are cylindrical and aligned along same longitudinal axis.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to an electromagnetic actuator comprising a magnetic circuit formed by a ferromagnetic yoke extending along a longitudinal axis, and a movable ferromagnetic core mounted to slide axially along the longitudinal axis of the yoke. The actuator comprises at least two coils and means for switching the coils from a series position to a parallel position and vice versa.

STATE OF THE PRIOR ART

It is known to use at least two different types of windings for the phases of calling and maintaining an electromagnetic actuator. Indeed, the optimization of the energy operation of the electromagnetic actuators is often taken into account at the time of their design. A known principle is to use a first type of winding at the time of the call phase and a second winding during the holding phase. The use of several specific windings is described in the state of the art, in particular in the following patents FR2290009 , US4227231 , US4609965 , EP1009003 . In general, the winding used for the call phase is sized to support the bulk of the calling power and the winding used for the holding phase is intended to provide the only ampere turns required to maintain the core in the closed position . Each of the windings is put into service according to the position of the core.

In addition, the need to use electromagnetic actuators with wide voltage supply ranges is also becoming a priority. Several solutions described in the following documents FR2568715 , EP1009003 , EP1009004 use means for regulating the supply voltage of the winding or coils. The voltage supplied to the windings is traditionally modulated according to PWM pulse width modulation.

The use of pulsed currents as described in the document of the state of the art EP0998623 does not allow to obtain a regulation of the electric current in the or coils and maintain said current complies with a setpoint. In addition, the use of pulsed currents does not achieve a satisfactory level of regulation. Indeed, the use of pulsed current involves a fixed and unmodulated duty cycle depending on the voltage. The current is either directly a function of the voltage or linked to the voltage by a fixed ratio. There is therefore no decoupling between the voltage and the current. Independence between control voltage and current is not possible. In addition, there is a detrimental influence of increasing the value of the resistance of the coil as a function of temperature. The electromagnetic actuator design, whose operation is both optimal in terms of power consumption and in terms of operating voltage range remains very difficult. Progress in one of the two areas of development is usually to the detriment of the other. In addition, the operation of electromagnetic actuators during the fallout or opening phase is generally not optimized.

SUMMARY OF THE INVENTION

The invention therefore aims to overcome the disadvantages of the state of the art, so as to provide an electromagnetic actuator with high energy efficiency.

The electromagnetic actuator according to the invention comprises control means comprising means for regulating the electric current flowing in said at least two coils, call means arranged to control the voltage supplied to said at least two coils during a closing operation of the actuator, and controlling the switching means to place said at least two coils in parallel mode to generate a first magnetic call flow to close the actuator. The control means comprise holding means arranged to control the current supplied to said at least two coils during a holding operation of the actuator in the closed position and to control the switching means to place said at least two windings in series mode to generate a second magnetic flux maintenance.

According to a preferred embodiment, the regulation means comprise a comparator comparing the value of an electric current flowing through said at least two coils to a setpoint, said comparator being connected to a corrector associated with an amplifier controlling a switch.

Advantageously, the regulation means comprises a control means for modulating the supply voltage of said at least two windings according to PWM type pulse width modulation.

Advantageously, the electromagnetic actuator comprises first and second coils.

According to a development mode of the invention, the switching means comprise a first opening means connected in series between a first terminal of the first coil and a first voltage supply terminal, a second terminal of the first coil being connected to a first terminal of the first coil. second voltage supply terminal through the control transistor. The switching means comprise a second opening means connected in series between the second terminal of the first coil and a second terminal of the second coil, the second coil having a first terminal connected to the first voltage supply terminal and the second terminal. connected to the second voltage supply terminal through the control transistor. A third opening means is directly connected in series between second terminal of the second winding and the first terminal of the second winding. At least one freewheel diode is connected in parallel and in reverse between the second terminal of the first coil and the first terminal of the second coil. The three opening means are arranged to receive commands from the call or hold means so as to be placed respectively in an open or closed state, the windings being in series mode when the first and second means of opening have opened and the third opening means is closed, the coils being in parallel mode when the first and second opening means are closed and the third opening means is open.

Preferably, the control means comprise measuring means for detecting the current flowing through the two coils.

According to a development mode of the invention, the control means comprise dropout means arranged so as to control a counter-voltage supplied to the two coils, and control the switching means to place the two coils in parallel mode to generate a third. magnetic flux of fallout to open the actuator.

Preferably, the dropout means comprise a fourth opening means connected in series with the freewheel diode, a Zener diode connected in parallel and in reverse across the freewheeling diode, the fourth opening means being arranged to be controlled by the control sub-unit so as to be in an open state and disconnect the freewheeling diode, a counter-voltage being applied across the windings.

Preferably, the control means comprise voltage measuring means able to detect the voltage between the first and second voltage supply terminals before the closing operation, and to control the voltage supplied to the coils according to the voltage detected during the closing operation.

Preferably, the electromagnetic actuator comprises first and second coils having the same ohmic resistance.

Preferably, the coils are identical and have the same inductance and the same number of turns.

Advantageously, the coils are arranged on two separate coils.

Advantageously, the coils are cylindrical and aligned along the same longitudinal axis.

In a particular embodiment, the electromagnetic actuator comprises test means cyclically controlling the change. configuration of said at least two coils during the holding phase, the test means sending commands to switching means for temporarily placing said at least two coils in parallel.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 représente un schéma électrique d'un actionneur électromagnétique à au moins deux bobinages selon un premier mode préférentiel de réalisation de l'invention ;
• la figure 2 représente un schéma électrique d'un actionneur électromagnétique à au moins deux bobinages selon un second mode préférentiel de réalisation de l'invention ;
• la figure 3 représente un schéma électrique d'une variante de réalisation des moyens de commutation d'un actionneur électromagnétique selon le premier mode préférentiel de réalisation de la figure 1 ;
• la figure 4 représente un schéma électrique d'une variante de réalisation des moyens de commutation d'un actionneur électromagnétique selon les modes de réalisation des figures 1 et 2 ;
• la figure 5 représente des courbes traçant l'évolution du rapport des tensions maximale et minimale d'alimentation en fonction du rapport des courants d'appel et de maintien ;
• la figure 6 représente une vue en perspective d'un mode particulier de réalisation d'un actionneur selon les modes de réalisation des figures 1 et 2 ;
• la figure 7A représente des courbes représentatives de l'évolution du courant dans un bobinage en phase d'appel en fonction de la tension d'alimentation, selon
• un mode de réalisation connu ;
• la figure 7B représente des courbes représentatives de l'évolution du courant dans un bobinage en phase d'appel en fonction de la tension d'alimentation, selon un mode de réalisation de l'invention.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, and represented in the accompanying drawings in which:

• the figure 1 represents a circuit diagram of an electromagnetic actuator with at least two coils according to a first preferred embodiment of the invention;
• the figure 2 represents a circuit diagram of an electromagnetic actuator with at least two coils according to a second preferred embodiment of the invention;
• the figure 3 represents a circuit diagram of an alternative embodiment of the switching means of an electromagnetic actuator according to the first preferred embodiment of the figure 1 ;
• the figure 4 represents a circuit diagram of an alternative embodiment of the switching means of an electromagnetic actuator according to the embodiments of the figures 1 and 2 ;
• the figure 5 represents curves plotting the evolution of the ratio of the maximum and minimum supply voltages as a function of the ratio of the inrush and holding currents;
• the figure 6 represents a perspective view of a particular embodiment of an actuator according to the embodiments of the figures 1 and 2 ;
• the Figure 7A represents curves representing the evolution of the current in a call phase winding as a function of the supply voltage, according to
• a known embodiment;
• the Figure 7B represents curves representative of the evolution of the current in a winding phase of call depending on the supply voltage, according to one embodiment of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

According to a first preferred embodiment, the electromagnetic actuator comprises a fixed magnetic circuit of ferromagnetic material. The magnetic circuit comprises a ferromagnetic yoke 2 extending along a longitudinal axis Y. A movable ferromagnetic core 3 is placed opposite the cylinder head. Said core is mounted to slide axially along the longitudinal axis Y of the yoke. The electromagnetic actuator comprises at least two windings L1, L2. Said at least two coils preferably extend along the longitudinal axis Y.

For example as shown on the figure 6 , the actuator is of type E. It can be envisaged other plunger actuator geometry such as U-type actuators. The actuators may or may not include polar expansion or permanent magnets.

According to a preferred embodiment of the invention, the actuator comprises first and second coils L1, L2. Switching means 10 place said at least two windings L1, L2 in series or parallel depending on the operating phase of the actuator.

Said at least two windings L1, L2 are connected in parallel during a call phase during which the farm actuator. During a closing operation of the actuator, said at least two windings L1, L2 generate a first call magnetic flux φ _call to move the mobile core 3 from a first position P1 to a second position P2.

Said at least two coils are connected in series during a holding phase during which the actuator is held in a position of closing. Said at least two windings L1, L2 generate a second holding magnetic flux φ _holding to keep the core 16 mobile in its second position P2.

Control means 20 control the switching means 10 to place the at least two windings L1, L2 in parallel mode or in series mode.

Control means 20 comprise means 22 for regulating the electric current flowing in the at least two windings L1, L2.

In the call and / or hold phase, the control means 20 regulate the electric current I flowing in the two windings L1, L2 of the actuator. This temporal regulation is preferably dependent on a setpoint that can be a function of several parameters taken alone or in combination.

The setpoint can be set according to a current profile defined according to its evolution as a function of time.

The setpoint can be set according to a time constant. A sudden transition between the call and hold phase is then observed after a predetermined time.

The setpoint can be set according to the position of the moving armature. A sudden transition between the call and hold phase is then observed when the moving armature of the actuator has reached a determined position.

In addition, the setpoint can also be set according to the desired closing time. This closing time is dependent on the power of the source on the call. This constraint can then have an impact on the consumption in the maintenance phase. The limitation of the consumption during the holding phase makes it possible to limit the heat dissipation.

As shown on the figure 1 this regulation is carried out by a corrector 223, which may be for example a PID (Proportional Integral Derivative) type regulator. The PID regulator is a control device allowing to carry out a closed-loop control of the actuator, the control having to operate even if the environmental conditions change, in particular when the supply voltage of the actuator is changed. The regulator is associated with an amplifier 224 which may for example be a pulse width modulation PWM (Pulse Width Modulation) type amplifier. The amplifier controls a switch 226. This modulation of the width of the pulses as a function of the voltage makes it possible to adjust the value of the current to the nearest of the setpoint. The actual current flowing through said at least two windings L1, L2 is measured by a sensor 225. A comparator 222 compares the value of said actual current with the setpoint. The current sensor 225 may for example be a measuring shunt such as a resistor R1 placed in series with said at least two windings L1, L2. The known value resistance is preferably low.

At each operating cycle (closing / holding), the regulation means 22 can reproducibly provide a stable electrical current. As shown on the Figure 7B , the electric current is then independent of the voltage and temperature variations. An actuator operating in a wide range of voltage is then obtained with a window of regulated currents as wide as possible. In addition, the operation is relatively insensitive to the conditions of use. The only limitations concern the specific limits of PWM type control. The regulation is indeed limited in a certain voltage range between a minimum value and a maximum value.

The principle of double winding makes it possible to increase the voltage range or the ratio in the inrush current and the holding current. Indeed, these quantities are linked by the coil resistor that is modified according to the operating phase (call or maintenance).

As an exemplary embodiment, as shown in the figure2 , the regulation means 22 comprises a control transistor TC for modulating the voltage supplied to said at least two windings L1, L2 according to PWM type pulse width modulation. The coil current measurement is performed via the resistor R1 associated with a filter capacitor. The measure is then compared that attacks a comparator to modulate the PWM and allow to obtain a regulation of the current.

The control means 20 comprise call means 23B, 24, 21, 22 arranged to control the voltage supplied to said at least two windings L1, L2 during a closing operation of the actuator.

The control means 20 comprise holding means 23B, 24, 21, 22 arranged to control the electric current supplied to said at least two windings L1, L2 during a holding operation of the actuator in the closed position.

According to a first preferred embodiment of the invention shown in the figure 1 , the switching means 10 comprise a first opening means T1 connected in series between a first terminal L1a of the first coil L1 and a first voltage supply terminal A. A second terminal L1b of the first coil L1 is connected to a second voltage supply terminal B through a control transistor TC regulating means 22.

The switching means 10 comprise a second opening means T2 connected in series between the second terminal L1 b of the first coil L1 and a second terminal L2b of the second coil L2. Said second winding L2 has a first terminal L2a connected to the first voltage supply terminal A and the second terminal L2b connected to the second voltage supply terminal B through the control transistor TC.

A third opening means T3 is directly connected in series between the second terminal L2b of the second coil L2 and the first terminal L1a of the second coil L2.

As shown on figures 1 and 2 at least one freewheeling diode D2 is connected in parallel and in reverse between the second terminal L1b of the first coil L1 and the first terminal L2a of the second coil L2. The diode D2 is therefore not busy when the first voltage supply terminal A is powered with a positive voltage.

The three opening means T1, T2, T3 are arranged to receive commands from a control sub-unit 24 so as to be placed respectively in an open and closed state and vice versa. The windings L1, L2 are in series mode when the first and second opening means T1, T2 are open and the third opening means T3 is closed. The windings L1, L2 are in parallel mode when the first and second opening means T1, T2 are closed and the third opening means T3 is open.

Preferably, the first and second opening means T1, T2 respectively comprise a transistor that can be controlled by the control sub-unit 24 of the control means 20. In addition, the third opening means T3 preferably comprises a transistor controlled by the control sub-unit 24.

The control means 20 comprise measuring means R1 for detecting the current flowing through the two windings L1, L2. The measuring means R1 comprises a measurement resistor connected in series between the control transistor TC and the second voltage supply terminal B.

According to an alternative embodiment of the first preferred embodiment as shown in FIG. figure 3 , the third opening means T3 comprises a switching diode D1 connected in parallel and in reverse to the second winding L2. The addition of the switching diode D1 ensures proper operation if the actuation of the first and second opening means T1, T2 is not synchronized.

According to a particular embodiment of the first preferred embodiment, the electromagnetic actuator comprises a first and a second coil L1, L2. The two coils L1, L2 have identical coils, and therefore substantially identical ohmic resistances, the same number of turns as well as the same inductance. Preferably, the coils L1, L2 are cylindrical and aligned along the same longitudinal axis Y.

Thanks to this configuration, it is possible to dissociate the antagonistic constraints encountered in the call phase and in the hold phase. In addition, the actuator according to the invention can be used for a wide range of supply voltage which makes it very versatile.

où τ_maxi correspond au rapport cyclique maximal égal au rapport entre la durée d'impulsion maximale et à la période d'envoi des impulsions et τ_min correspond au correspond au rapport cyclique minimal égal au rapport entre la durée d'impulsion minimale et à la période d'envoi des impulsions. Rbobine_maxi est égal à la résistance maximale du bobinage en phase l'appel et Rbobine_mini est égal la résistance minimale du bobinage en phase de maintien.The minimum and maximum resistances of the winding (s) used fix the width of the supply voltage range U _max / U _min depending on the inrush and hold currents and the control loop duty cycles. In a traditional configuration where a single winding is used with current control on call and hold, the ratio between the maximum operating voltage and the minimum voltage is defined as follows: $${\mathrm{U}}_{\max }\mathrm{/}{\mathrm{U}}_{\mathrm{mini}}\mathrm{=}\left({\mathrm{\tau }}_{\max }\mathrm{\times }{\mathrm{Rcoil}}_{\mathrm{mini}}\right)\mathrm{/}\mathrm{(}{\mathrm{\tau }}_{\min }\mathrm{\times }{\mathrm{Rcoil}}_{\max }\mathrm{)}\mathrm{\times }\mathrm{1}\mathrm{/}\left({\mathrm{I}}_{\mathrm{call}}\mathrm{/}{\mathrm{I}}_{\mathrm{retention}}\right)$$

where τ _max is the maximum duty cycle equal to the ratio between the maximum pulse duration and the pulse sending period and τ _min is the minimum duty cycle equal to the ratio of the minimum pulse duration and the pulse sending period. Rbobine _max is equal to the maximum resistance of the winding in phase the call and Rbobine _mini is equal to the minimum resistance of the winding in phase of maintenance.

In a traditional configuration, the variation of the winding resistance depends essentially on the temperature.

According to the invention, the ratio between the maximum operating voltage and the minimum voltage is defined as follows: $${\mathrm{U}}_{\max }\mathrm{/}{\mathrm{U}}_{\mathrm{mini}}\mathrm{=}\mathrm{kx}\left({\mathrm{\tau }}_{\max }\mathrm{\times }{\mathrm{Rcoil}}_{\mathrm{mini}}\right)\mathrm{/}\mathrm{(}{\mathrm{\tau }}_{\min }\mathrm{\times }{\mathrm{Rcoil}}_{\max }\mathrm{)}\mathrm{\times }\mathrm{1}\mathrm{/}\left({\mathrm{I}}_{\mathrm{call}}\mathrm{/}{\mathrm{I}}_{\mathrm{retention}}\right)$$

Given that the maximum and minimum resistances of the windings on call and on hold are adjustable and no longer depend only on the temperature, we can multiply by a factor k the ratio between the maximum voltage of use and the minimum voltage U _max / U _min . For example, if the resistances of the two windings L1, L2 are identical, the passage between the serial mode and the parallel mode makes it possible to obtain a factor k equal to 4. It is then possible to increase the width of the supply voltage range. and / or the ratio of the call / hold current as required thereby releasing the constraint on the impedance seen by the control circuit.

où Rbobine_maxi est égal à la résistance du bobinage à une température maximale d'utilisation, U_mini est égal à la tension minimale de la plage d'utilisation.According to a development mode of the invention, the maximum call current is determined as a function of a minimum voltage value U _min of the voltage range, for a maximum operating temperature and the maximum duty cycle. The maximum calling current is expressed according to the following equation: $${\mathrm{I}}_{\mathrm{call}}\mathrm{=}{\mathrm{U}}_{\mathrm{mini}}\mathrm{\times }\left({\mathrm{\tau }}_{\max }\right)\mathrm{\times }{\mathrm{Rcoil}}_{\max }$$

where Rbobine _max is equal to the winding resistance at a maximum operating temperature, U _min is equal to the minimum voltage of the operating range.

où Rbobine_mini est égal à la résistance du bobinage à une température minimale d'utilisation, U_maxi est égal à la tension maximale de la plage d'utilisation.In addition, the minimum holding current is determined as a function of a maximum voltage value U _maximum of the voltage range, for a minimum operating temperature and the maximum duty cycle. The minimum holding current is expressed according to the following equation: $${\mathrm{I}}_{\mathrm{retention}}\mathrm{=}\mathrm{Umax}\mathrm{\times }\left({\mathrm{\tau }}_{\min }\right)\mathrm{\times }{\mathrm{Rcoil}}_{\mathrm{mini}}$$

where Rbobine _mini is equal to the winding resistance at a minimum operating temperature, U _max is equal to the maximum voltage of the operating range.

The dashed curve 50 of the figure 5 represents the evolution of the ratio of the voltages U _maxi / U _mini as a function of the ratio of the currents of call and of maintenance I _call / I _hold when the impedance of the windings varies between the call phase and the hold phase. The curve in solid line 51 represents the evolution of the ratio of the voltages U _maxi / U _mini as a function of the ratio of the currents of call and maintenance I _call / I _maintenance when the impedance of the coils does not vary.

As shown on the figure 5 it is thus possible to increase either the width of the voltage range U _max i / U _min and / or the ratio between the inrush current and the I _call / I _{hold current} . In order to obtain a maximum voltage range U _max / U _min and a ratio current I _call / I the most important _maintenance , it is desirable to have a winding having the lowest resistance to the call and the highest to maintain . According to a particular embodiment, the resistance can easily be multiplied by 4 (K = 4) between the call and the hold.

According to a second preferred embodiment presented on the figure 2 , the control means 20 of the electromagnetic actuator comprise dropout means 23A, 24. The dropout means 23A, 24 are arranged to control a counter-voltage supplied to the two windings L1, L2 and to control the means of switching 10 to place the two windings L1, L2 in parallel mode to generate a third fallout magnetic flux φ _dropped to open the actuator.

The dropout means 23A, 24 comprise a fourth opening means T4 connected in series with the freewheeling diode D2. They comprise a Zener diode Dz connected in parallel and inversely across the freewheeling diode D2. The fourth opening means T4, preferably a transistor, is arranged to receive commands from the control sub-unit 24 so as to be in an open state and disconnect the freewheeling diode D2, a counter-current. voltage is then applied across the windings L1, L2.

The dropout means 23A, 24 comprise a fifth opening means T5 connected in series with the Zener diode Dz. The fifth T5 opening medium is arranged to receive commands from the control sub-unit 24 so as to be in a closed state during a dropout operation, the fifth opening means T5 being open during the closing or holding operations of the actuator .

The dropout means allow the passage of the windings L1, L2 in a parallel mode and facilitate the fallout of the electromagnet by reducing the level of against voltage required. This leads to a simplification of the electronic circuits especially as regards Asics components that can operate at lower voltages. Thus, with respect to the known solutions, for the same value of current at the maintenance and for the same value of against voltage, the passage in parallel mode of the coils makes it possible to demagnetize more quickly and thus to open the actuator more quickly. In addition, for the same value of current maintenance, for the same demagnetization time, the fact of placing the windings in parallel mode allows to demagnetize with a lower voltage against. By way of example, the same opening speed is obtained with a counter-voltage value that is twice as low.

According to another variant embodiment of the second preferred embodiment, the third opening means T3 comprises a transistor connected in series with the switching diode D1.

According to the embodiments represented on the figures 1 and 2 the control means 20 comprise voltage measuring means 25 designed to detect the voltage U _AB between the first and second voltage supply terminals A, B before the closing operation, and to control the voltage supplied to the coils L1, L2 depending on the supply voltage U _AB detected during the closing operation.

According to an alternative embodiment of the preferred embodiments, each winding L1, L2 may comprise a freewheel diode connected in parallel and in reverse at these terminals.

When the command orders sent to the actuator, especially at the time of the holding phase, are transmitted over long distances with power lines, the presence of parasitic capacitances on the power lines can generate a residual voltage across the actuator. This residual voltage can in particular change the time required to detect the dropout voltage. By way of example, the time required to detect the dropout voltage can be increased.

Thus, with actuators of very low power consumption and in the presence of very long lengths of power cable, the cancellation of the supply voltage does not immediately cause the opening of the actuator. The parasitic capacitances are loaded and behave like a filter or a screen. This problem is unavoidable when the actuator is very low consumption and is powered with a high voltage.

The deleterious effect of parasitic capacitances on the opening time of an actuator can be limited by reducing the impedance of the actuator as seen from the voltage supply source. Indeed, the fact of reducing the impedance of the actuator makes it possible to absorb a greater total amount of energy, by absorbing in particular that contained in the parasitic capacitances.

The amount of total energy absorbed under these conditions is however limited by the ability of the actuator to withstand thermal stresses. Energy due to voltage variation of the power source in the presence of stray capacitances must be detectable and absorbable without causing excessive heating of the actuator.

According to a particular embodiment of the preceding modes, the control means 20 of the electromagnetic actuator comprise test means cyclically controlling the configuration change of said at least two windings L1, L2. During the holding phase, the test means send commands to switching means 10 to temporarily place said at least two windings L1, L2 in parallel. The impedance reduction of the actuator is then through the configuration change of the windings from the serial mode to the parallel mode. Placing the coils L1, L2 in parallel mode has the consequence of reducing the impedance of the actuator by a factor k, the factor k being equal to the ratio between the resistance of the windings L1, L2 in series mode and the resistance of the coils in parallel mode.

The time constant of the electric circuit RLC consisting of the windings L1, L2 and parasitic capacitances is also reduced by a factor k. The drop in voltage across said capacitors is therefore faster and the detection time of the dropout voltage is thus reduced by a factor k. It is also possible to increase the speed of the voltage drop by increasing the level of the reference current of the coil control. In the latter case, it will be limited by a risk of overheating of the actuator. The series-parallel configuration change is preferably done cyclically. The duration of this test phase, during which the windings are placed in parallel mode, must be integrated in the detection time of the dropout voltage.

Claims (14)

Electromagnetic actuator comprising: a magnetic circuit formed by a ferromagnetic yoke (2) extending along a longitudinal axis (Y), and a movable ferromagnetic core (3) mounted to slide axially along the longitudinal axis (Y) of the yoke, at least two windings (L1, L2), - switching means (10) of the windings (L1, L2) from a series position to a parallel position and vice versa, characterized in that it comprises control means (20) comprising: regulating means (22) for the electric current flowing in the at least two windings (L1, L2), - Calling means (23B, 24, 21, 22) arranged so as to: controlling the voltage supplied to said at least two windings (L1, L2) during a closing operation of the actuator, and - control the switching means (10) to place said at least two coils (L1, L2) in parallel mode to generate a first magnetic call flow (φappel) to close the actuator, holding means (23B, 24, 21, 22) arranged in such a way as to: - control the current supplied to said at least two coils (L1, L2) during a holding operation of the actuator in the closed position and, - Control switching means (10) for placing said at least two windings (L1, L2) in series mode to generate a second magnetic flux maintenance (φmaintien). Electromagnetic actuator according to claim 1 characterized in that the regulating means (22) comprise a comparator (222) comparing the value of an electric current flowing through said at least two windings (L1, L2) to a setpoint, said comparator (222 ) being connected to a corrector (223) associated with an amplifier (224) controlling a switch (226) Electromagnetic actuator according to Claim 2, characterized in that the regulating means (22) comprise a control means (TC) for modulating the supply voltage of the at least two windings (L1, L2) according to pulse-width modulation. PWM type. Electromagnetic actuator according to one of claims 1 to 3 characterized in that it comprises a first and a second windings (L1, L2). Electromagnetic actuator according to Claim 4, characterized in that the switching means (10) comprise: a first opening means (T1) connected in series between a first terminal (L1a) of the first coil (L1) and a first voltage supply terminal (A), a second terminal (L1b) of the first coil ( L1) being connected to a second voltage supply terminal (B) through the control transistor (TC), a second opening means (T2) connected in series between the second terminal (L1 b) of the first coil (L1) and a second terminal (L2b) of the second coil (L2), said second coil (L2) having a first terminal (L2a) connected to the first voltage supply terminal (A) and the second terminal (L2b) connected to the second voltage supply terminal (B) through the control transistor TC, a third opening means (T3) directly connected in series between second terminal (L2b) of the second winding (L2) and the first terminal (L1a) of the second winding (L2), at least one freewheeling diode (D2) connected in parallel and inversely between the second terminal (L1b) of the first coil (L1) and the first terminal (L2a) of the second coil (L2),
the three opening means (T1, T2, T3) being arranged to receive commands from the call or hold means (23B, 24, 21, 22) so as to place themselves respectively in a state of opening or closing ; the windings (L1, L2) being in series mode when the first and second opening means (T1, T2) are open and the third opening means (T3) is closed, the coils (L1, L2) being in parallel mode when the first and second opening means (T1, T2) are closed and the third opening means (T3) is open. Electromagnetic actuator according to any one of the preceding claims, characterized in that the control means (20) comprise measuring means (R1) for detecting the current flowing through the two coils (L1, L2). Electromagnetic actuator according to any one of the preceding claims, characterized in that the control means (20) comprise drop-off means (23A, 24, 30) arranged in such a way as to: - control a counter-voltage supplied to the two windings (L1, L2), - Control the switching means (10) for placing the two windings (L1, L2) in parallel mode to generate a third magnetic flux fallout (φretomb). Electromagnetic actuator according to Claim 7, characterized in that the dropout means (23A, 24, 30) comprise: a fourth opening means (T4) connected in series with the freewheeling diode (D2), a Zener diode (Dz) connected in parallel and inversely across the freewheeling diode (D2), the fourth opening means (T4) being arranged to be driven by the control sub-unit (24) so as to be in an open state and disconnect the freewheeling diode (D2), a counter-voltage being applied across the windings (L1, L2). Electromagnetic actuator according to any one of the preceding claims, characterized in that the control means (20) comprise voltage measuring means (25) capable of: detecting the voltage (U _AB ) between the first and second voltage supply terminals (A, B) before the closing operation, and, - control the voltage supplied to the windings (L1, L2) according to the supply voltage (U _AB ) detected during the closing operation. Electromagnetic actuator according to any one of the preceding claims, characterized in that it comprises a first and a second winding (L1, L2) having the same ohmic resistance Electromagnetic actuator according to Claim 10, characterized in that the coils (L1, L2) are identical and have the same inductance and the same number of turns. Electromagnetic actuator according to one of claims 10 to 11 characterized in that the coils (L1, L2) are arranged on 2 separate coils. Electromagnetic actuator according to one of claims 10 to 12 characterized in that the coils (L1, L2) are cylindrical and aligned along the same longitudinal axis (Y). Electromagnetic actuator according to any one of the preceding claims, characterized in that it comprises test means cyclically controlling the configuration change of said at least two coils (L1, L2) during the holding phase, the means test device sending commands to switching means (10) for temporarily placing said at least two coils (L1, L2) in parallel.

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