EP2320438A1 - Electromagnetic actuator and electrical contactor comprising such actuator - Google Patents

Abstract

The actuator has a control unit providing a ring voltage during closing operation of the actuator, and a maintaining voltage during maintaining operation of the actuator in a closed position, to a control coil (3). The control unit has a maintaining voltage regulating unit (50) with a step down transformer (51) that step-downs the ring voltage for providing the intermediate voltage lower and proportional to the ring voltage. Another step down transformer (52) step-downs the intermediate voltage for providing the maintaining voltage that is lower and proportional to the intermediate voltage.

Description

The present invention relates to an electromagnetic actuator comprising a magnetic circuit comprising a magnetic yoke collaborating with a movable armature controlled movement between an open position and a closed position. At least one control coil is for generating a magnetic flux for moving or holding the moving armature opposite the magnetic yoke. Control means are provided for supplying the control coil with a call voltage during a closing operation of the actuator, and a holding voltage during a holding operation of the actuator in the closed position.

The invention also relates to a switch-type electrical switch device comprising an electromagnetic actuator.

STATE OF THE ART

The operation of an electromagnetic actuator in the holding phase is generally related to internal conditions of use depending in particular on the state of aging of the apparatus.

With reference to Figures 1A to 1C a switch-type electrical switch device comprises, in known manner, an electromagnetic type actuator 1, one or more poles (for example three poles for a three-pole contactor) with, for each pole, a movable member set in motion by the actuator, one or more movable contacts 21 carried by the movable member and one or more fixed contacts 20. The actuator 1 more particularly comprises a fixed yoke 10 and a movable armature 11 adapted to move relative to the fixed yoke 10 between two positions , an open position ( Figure 1 A) and a closed position ( Figure 1 C) . The electromagnetic actuator also comprises a control coil 3 controlled by a control current in order to move the mobile armature 11 from its open position to its closed position and a return spring 4 positioned between its fixed yoke 10 and its movable armature 11 to move the movable armature 11 from its closed position to its open position. On the Figures 1A to 1C , the movable member is for example a movable double break bridge carrying two movable contacts 21 movable between two states, an open state and a closed state, according to the position of the movable armature 11 of the actuator 1. For each pole , the electrical apparatus comprises a pole spring 5 for crushing the movable contacts 21 against the fixed contacts 20 when the movable armature 11 is in the closed position. The invention described below will be able to operate with a simple rupture type mobile member.

On the Figure 1A under the effect of the force exerted by the return spring 4, the movable armature 11 is in the open position. On each pole, the movable contacts 21 are then in the open state.

On the Figure 1B , the movable armature 11 is in its closing stroke by injecting a control current into the control coil 3 of the actuator 1. The control current must be sufficient to counter the effort provided. by the return spring 4. In this figure, the movable contacts 21 are brought to the closed state by the actuator 1 but the pole spring 5 is not biased.

On the figure 1C , the movable armature 11 completes its closing stroke and is kept in its closed position relative to the fixed yoke 10 by injecting a sufficient control current into the control coil 3 of the actuator 1. The return spring 4 is compressed to the maximum between the movable armature 11 and the fixed breech 10. On this figure 1C the movable contacts 21 are kept in the closed state and are crushed against the fixed contacts 20 by means of the pole spring 5 which is compressed by means of the actuator 1.

Depending on the level of wear of the fixed and moving contacts, the pole springs 5 will be more or less compressed and the force provided by the actuator 1 will be more or less important. Indeed, the less the contacts 20, 21 are worn, the more pole springs 5 are compressed and therefore the force provided by the actuator 1 to compress these springs must be important. Therefore, it is possible to correlate the level of wear of the contacts with the force provided by the actuator to compress the pole springs 5.

Energy efficiency is becoming an increasingly important customer value. When using contactor switching apparatus, the holding phase requires energy to maintain the apparatus in a given position. Setting the current value is therefore essential. Moreover, if a regulation strategy is implemented in order to optimize the "just needed" current, it is important to have a system that offers a sufficiently precise adjustment range.

The main problem is that the existing power supply must be used both during the call phase and during the holding phase, and that the order of magnitude of the energies implemented is very different in these two cases. Indeed, the energy requirement during the different phases of operation can have significant differences. For example, the energy required during the holding phase can be substantially between 1 and 4% of the useful energy in the calling phase. With such a power supply device, it is sometimes difficult to have an accurate power level in the holding phase.

Indeed, according to a first example of application of a known power supply device, the maximum inrush current is equal to 2A, and the holding current can be set to a first initial value equal to 80mA. In addition, the setting of the holding current in the control coil is done with a setting step of a value equal to 1% of the maximum inrush current. A variation of the holding current of plus or minus 1% then corresponds to a variation of plus or minus 20mA. In other words, given the value of the setting step (1%), the holding current can take in particular the following values 60mA (80mA - 20mA) or 100mA (80mA + 20mA). Thus, the setting step of 1% reduced to a value of the holding current equal to 80 mA, sets the accuracy level of adjustment of said holding current to ± 25% of the initial value fixed. In addition, according to a second example of application, the holding current can be set to a second initial value equal to 20 mA (in the case of a worn contactor). A variation of the holding current of plus or minus 1% corresponds to a variation of plus or minus 20mA. In other words, given the value of the setting step (1%), the holding current can take in particular the following values 0mA (20 mA - 20mA) or 40mA (20mA + 20 mA). Thus, the setting step of 1% reduced to a value of a holding current equal to 20mA, sets the accuracy level of adjustment of said holding current to ± 100% of the fixed initial value.

These accuracy levels are relatively low and are unsatisfactory for some applications where the accuracy level of the holding current must be high.

Some existing solutions recommend the use of two coils. A first coil is then dedicated to the call phase and a second coil is then dedicated to the holding phase. An optimization of the geometry of the windings of the call and hold coils makes it possible to adapt the power value consumed respectively in the call phase and in the hold phase. However, these solutions have the disadvantage of an additional electronic system for electrical switching between the control circuit and the coils used. In addition, the electronic power supply systems do not necessarily include means for precisely regulating the supply of the coils, in particular of the holding coil.

Other solutions may use sophisticated electronic solutions to achieve current regulation accuracy in the hold phase. These solutions using high precision components are expensive. In addition, these solutions, generally using a PWM type of amplitude modulation based technology, can cause the production of electromagnetic disturbances and be the source of CEM type radiation.

SUMMARY OF THE INVENTION

The invention therefore aims to overcome the disadvantages of the state of the art, so as to provide an electrical switch device whose operation can be optimized to reduce its power consumption.

The control means of the electromagnetic actuator according to the invention comprise means for regulating the holding voltage comprising a first voltage step down of the call voltage to provide a lower intermediate voltage and proportional to the call voltage. The said holding voltage regulating means comprise a second voltage step of the intermediate voltage for providing a lower holding voltage proportional to the intermediate voltage.

According to a first development mode of the invention, the first voltage step is intended to generate a fixed intermediate voltage, and the second voltage step is intended to generate a variable sustain voltage proportional to the fixed intermediate voltage.

Preferably, the second voltage step-down comprises means for modulating the fixed intermediate voltage according to PWM-type pulse width modulation.

According to a first mode of development of the invention, the first voltage step-down is intended to generate a variable intermediate voltage, and the second voltage step-down is intended to generate a fixed holding voltage proportional to said variable intermediate voltage.

Preferably, the first voltage step-down comprises means for modulating the call voltage according to PWM-type pulse width modulation.

According to a first mode of development of the invention, the first voltage step is intended to generate a variable intermediate voltage, and the second voltage step is intended to generate a variable sustain voltage proportional to said variable intermediate voltage.

Preferably, the first voltage step-down comprises means for modulating the call voltage according to PWM-type pulse width modulation and the second voltage step-down device comprises means for modulating the variable intermediate voltage according to pulse modulation. in width of PWM type.

Preferably, the control means comprise means for measuring the control current in the actuating coil and means for determining a wear level of the fixed and moving contacts from the control current during the separation of the moving armature relative to the fixed yoke.

Advantageously, the control means comprise means for determining, as a function of the wear level of the contacts, an optimum control current for holding the moving armature in the closed position, the regulation means controlling a holding voltage supplied to the control coil.

Switching type electric switch apparatus according to the invention comprises a movable member able to move between an open state and a closed state, said member carrying at least one moving contact with respect to a fixed contact for controlling an electric circuit.

BRIEF DESCRIPTION OF THE FIGURES

• ● les figures 1A, 1B et 1C illustrent schématiquement le principe connu de fonctionnement d'un appareil électrique interrupteur de type contacteur ;
• ● la figure 2 montre schématiquement le profil d'effort suivi par l'actionneur d'un appareil électrique interrupteur de type contacteur ;
• ● la figure 3 représente un schéma de principe des moyens de commande d'un actionneur selon un premier mode préférentiel de réalisation de l'invention ;
• ● la figure 4 représente un schéma fonctionnel des moyens de commande selon la figure 3 ;
• ● la figure 5 représente un schéma de principe des moyens de commande d'un actionneur selon un seconde mode préférentiel de réalisation de l'invention ;
• ● la figure 6 représente un schéma fonctionnel des moyens de commande selon la figure 5 ;
• • la figure 7 représente un schéma de principe des moyens de commande d'un actionneur selon un troisième mode préférentiel de réalisation de l'invention ;
• • la figure 8 représente un schéma fonctionnel des moyens de commande selon la figure 7 ;
• • la figure 9 représente les courbes de courant et de tension de maintien fournies par les moyens de commande d'un actionneur de type connu ;
• • la figure 10 représente les courbes de courant et de tension de maintien fournies par les moyens de commande d'un actionneur selon les modes de réalisation de l'invention.

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

• ● the FIGS. 1A, 1B and 1C schematically illustrate the known principle of operation of a switch-type electrical switch-type apparatus;
• ● the figure 2 shows schematically the force profile followed by the actuator of a switch-type electrical switch-type apparatus;
• ● the figure 3 represents a block diagram of the control means of an actuator according to a first preferred embodiment of the invention;
• ● the figure 4 represents a block diagram of the control means according to the figure 3 ;
• ● the figure 5 represents a block diagram of the control means of an actuator according to a second preferred embodiment of the invention;
• ● the figure 6 represents a block diagram of the control means according to the figure 5 ;
• • the figure 7 represents a block diagram of the control means of an actuator according to a third preferred embodiment of the invention;
• • the figure 8 represents a block diagram of the control means according to the figure 7 ;
• • the figure 9 represents the current and sustain voltage curves provided by the control means of an actuator of known type;
• • the figure 10 represents the current and holding voltage curves provided by the control means of an actuator according to the embodiments of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

According to one embodiment of the invention, the electromagnetic actuator 100 comprises a magnetic circuit 1 comprising a magnetic yoke 10 collaborating with a movable armature 11 controlled in movement between an open position and a closed position. The electromagnetic actuator 100 comprises at least one control coil 3 intended to generate a magnetic flux for moving or holding the movable armature 11 opposite the magnetic yoke 10.

According to a particular embodiment of the invention, the magnetic yoke 10 preferably comprises an E-shaped section comprising two outer branches, at least one central branch, and a transverse reinforcement secured to a first end of the outer and central branches. The movable armature 11 is placed vis-à-vis the second ends of the outer branches and moves in translation. The control coil 3 comprising a longitudinal axis substantially coincides with that of the central branch of the magnetic yoke 10 in the form of E. In fact, said control coil 3 is wound on the central branch of the magnetic yoke 10. In addition, a return spring 4 is positioned between the magnetic yoke 10 and the movable armature 11 to move the movable armature 11 from its closed position to its open position.

By way of example, the actuator according to the invention may be intended for a switch-type electrical switch-type apparatus comprising one or more electric poles (for example three poles for a three-pole contactor). As shown on the FIGS. 1A, 1B and 1C the mobile armature 11 is then associated with a movable member able to move between an open state and a closed state. The movable member carries at least one movable contact 21 with respect to a fixed contact 20 for controlling an electrical circuit. Each electrical pole of the contactor comprises at least one fixed contact 20 and a movable contact 21. The movable member is for example a double breakable movable bridge carrying two movable contacts 21 movable between two states, an open state and a closed state, according to the position of the mobile armature 11 of the actuator 1. For each pole, the electrical apparatus comprises a pole spring 5 for crushing the movable contacts 21 against the fixed contacts 20 when the movable armature 11 is in position closure. The invention described below will be able to operate with a simple rupture type mobile member. For reasons of simplification, Figures 1A to 1C show only one pole of the electrical switch device. It should be understood that the invention applies to all the poles of the apparatus.

On the Figure 1A under the effect of the force exerted by the return spring 4, the movable armature 11 is in the open position. On each pole, the movable contacts 21 are then in the open state.

On the Figure 1B , the movable armature 11 is in its closing stroke by injecting a control current into the control coil 3 of the actuator 1. The control current must be sufficient to counter the effort provided. by the return spring 4. In this figure, the movable contacts 21 are brought to the closed state by the actuator 1 but the pole spring 5 is not biased.

On the figure 1C , the movable armature 11 completes its closing stroke and is kept in its closed position relative to the fixed yoke 10 by injecting a sufficient control current into the control coil 3 of the actuator 1. The return spring 4 is therefore compressed to the maximum between the movable armature 11 and the fixed breech 10. On this figure 1C , the movable contacts 21 are kept in the closed state and are crushed against the fixed contacts 20 by means of the spring of pole 5 which is compressed by the actuator 1.

According to another embodiment not shown, the movable armature comprises a transverse armature carried to pivot on a central branch of the E-shaped magnetic circuit between two stable positions. Each stable position of the armature corresponds to an open or closed electrical state of electrical contacts of the contactor.

The electromagnetic actuator 100 comprises control means 2 for generating a voltage across the control coil 3 to provide a control current i (t) to said coil.

The control means 2 are intended to supply a call voltage U to the control coil 3 during a closing operation of the actuator. As an example of application, the call voltage U is equal to the DC voltage of a fixed bus (Direct Current Bus). The call voltage is equal to 320V. The control means 2 are also intended to supply a holding voltage% u to the control coil 3 during a holding operation of the actuator 100 in the closed position.

The control means 2 according to the preferred embodiments comprise means 50 for regulating the holding voltage. The regulating means comprise a first voltage step-down 51, 54, 56 of the calling voltage U to provide a first intermediate supply voltage. The intermediate supply voltage is lower and proportional to the call voltage U. The regulating means 50 further comprise a second voltage step-down 52, 55, 57 of the intermediate voltage to provide a holding voltage% u. The holding voltage is lower and proportional to the intermediate supply voltage. The holding voltage is applied across the control coil 3.

Preferably, a freewheel device D2 is present in parallel with the control coil 3 in order to avoid overvoltages across the switches and to allow continuity of current in said coil.

According to a first preferred embodiment of the invention such that represented on the Figures 3 and 4 , the first voltage step-down 51 is intended to generate a fixed intermediate voltage u. The second voltage step-down 52 is intended to generate a holding voltage% u variable proportional to the intermediate voltage u fixed. Preferably, the second voltage step-down 52 comprises means for modulating the fixed intermediate voltage according to PWM-type pulse width modulation.

In the call phase, the control means 2 comprise a control unit (control unit) controlling a first switch T1 placed in series with the control coil 3. The control unit places said first switch in conductive position. The control unit controls a second switch T2 connected between the control coil 3 and the regulation means 50. The second switch T2 is placed in the open position. The current in the control coil 3 is then maximal. For example, the call phase lasts about 50 ms. As an exemplary embodiment, the first and second switches T1, T2 may be transistors.

In the holding phase, the control unit (Control unit) opens the first switch T1 and applies to the second switch T2 PWM modulated signal. The maintenance phase begins after the call phase. The first voltage down regulator 51 (fixed supply) provides a fixed intermediate voltage which is then applied through the second switch T2 and the diode D1 in the control coil 3. The modulation of the PWM type control applied to the second switch T2 allows to vary the average value of the current in the control coil 3.

The diode D1 makes it possible to use a second low-voltage switch T2 and to protect it from the call voltage U supplied by the first switch T1 during the calling phase.

The amplitude of the holding current of a contactor can vary greatly depending on various parameters and in particular the state of wear of the contactor. The holding current in the control coil 3 can vary by a factor of 1 to 4. As an example of application, the holding current varies between 20mA and 80mA while the maximum inrush current is order of 2A.

According to an exemplary application of the first embodiment, the first voltage step 51 sets a first intermediate current value equal to 100 mA, ie 5% of 2A. The second voltage step-down 52 sets the sustain current at a first initial value equal to 80mA (80%). A variation of the holding current of plus or minus 1% corresponds to a variation of plus or minus 1 mA. In other words, given the value of the setting step (1%), the holding current can take in particular the following values 79mA (80mA - 1 mA) or 81 (80mA +1 mA). Thus, the setting step of 1% reduced to a value of the holding current equal to 80 mA, sets the accuracy level of adjustment of said holding current to ± 1.25% of the fixed initial value. According to a second example of application, the holding current can be set to a second initial value equal to 20 mA (in the case of a worn contactor). A variation of the holding current of plus or minus 1% corresponds to a holding current variation of plus or minus 1mA. In other words, given the value of the setting step (1%), the holding current can take in particular the following values 19mA (20 mA - 1 mA) or 21 mA (20mA +1 mA). Thus, the setting step of 1% reduced to the value of a holding current equal to 20 mA, sets the accuracy level of adjustment of said holding current to ± 5% of the initial value fixed. These levels of precision are higher than those obtained with known feed means.

According to a second preferred embodiment of the invention as represented on the Figures 5 and 6 , the first voltage step-down 54 is intended to generate a variable intermediate voltage u. The second voltage step-down 55 is intended to generate a fixed holding voltage% u proportional to the variable intermediate voltage u. Preferably, the first buckener 54 comprises means for modulating the call voltage U according to PWM pulse width modulation.

In the call phase, the control means 2 comprise a control unit (control unit) driving a first switch T1 so that it is in the conductive position. The control unit places a second switch T2 in the open position. The current in the control coil 3 is then maximal. For example, the call phase lasts about 50 ms. As an example of embodiment, the first and second switches T1, T2 may be transistors.

In the holding phase, the control unit controls the opening of the first switch T1 and applies to the second switch T2 a PWM modulated signal. The maintenance phase begins after the call phase. Thanks to the PWM type control applied to the second switch T2, the call voltage U, preferably equal to that of the fixed bus (Direct Current Bus), is modulated. The second voltage step-down 55 has a fixed divisor which reduces the modulated voltage to provide a hold voltage% u to the control coil 3. The hold voltage is applied to the control coil 3 through the diode D1. The modulation of the PWM control applied to the second switch T2 makes it possible to vary the mean value of the current in the control coil 3.

The diode D1 makes it possible to protect the fixed divisor output from the call voltage supplied by the switch T1 during the call phase.

According to an exemplary application of the second embodiment, the first variable voltage step 54 provides a first intermediate current value equal to 1.6A, ie 80% of 2A. The second voltage step 55 sets the sustain current at a first initial value equal to 80 mA (5%). A variation of the holding current of plus or minus 1% corresponds to a variation of plus or minus 1 mA. In other words, given the value of the setting step (1%), the holding current can take in particular the following values 79mA (80mA - 1 mA) or 81 (80mA +1 mA). Thus, the setting step of 1% reduced to a value of the holding current equal to 80 mA, sets the accuracy level of adjustment of said holding current to ± 1.25% of the fixed initial value. According to a second example of application, the first variable voltage step 54 provides a first intermediate current value equal to 0.4A, ie 20% of 2A. The second voltage step 55 sets the holding current at a second initial value equal to 20 mA (in the case of a worn contactor). A variation of the holding current of plus or minus 1% corresponds to a holding current variation of plus or minus 1mA. In other words, given the value of the setting step (1%), the holding current can take in particular the following values 19mA (20 mA - 1 mA) or 21 mA (20mA +1 mA). Thus, the setting step of 1% reduced to the value of a holding current equal to 20 mA, sets the accuracy level of adjustment of said holding current to ± 5% of the initial value fixed. These levels of precision are higher than those obtained with known feed means.

According to a third preferred embodiment of the invention as represented on the Figures 7 and 8 , the first voltage step-down 56 is intended to generate a variable intermediate voltage u. This first voltage step-down 56 is composed of a switch T1 and smoothing means 58 of the intermediate voltage u. The second voltage step-down 57 is intended to generate a holding voltage% u variable proportional to the intermediate voltage u variable. Preferably, the first downcomer comprises means for modulating the call voltage U according to PWM type pulse width modulation. Preferably, the second voltage step-down comprises means for modulating the variable intermediate voltage according to PWM-type pulse width modulation. Associating two variable functions in series provides additional flexibility and control accuracy.

In the call phase, the control means 2 comprise a control unit (control unit) controlling the first and second switches T1 and T2 so that they are always in the conductive position. The inrush current in the control coil 3 is then maximal. For example, the call phase lasts about 50 ms.

In the hold phase, the control unit applies a different PWM pulse modulation to each of the switches T1 and T2. The maintenance phase begins after the call phase.

The first voltage step-down 56 is controlled by the control unit. The voltage applied by the switch T1 from the fixed bus (Direct Current Bus) at the input of the smoothing means is of the PWM type. The smoothing means 58 transforms it into a continuous equivalent voltage. This continuous equivalent voltage is then modulated by the second voltage step by the application of a PWM command on the switch T2. This modulated voltage makes it possible to vary the value average of the current in the control coil 3.

According to a first example of application of the third embodiment, the first voltage step set a first intermediate current value equal to 100mA, ie 5% of 2A. The second voltage buckener sets the holding current to a first initial value of 80mA (80%). A variation of the holding current of plus or minus 1% corresponds to a variation of plus or minus 1mA. In other words, given the value of the setting step equal to 1%, the holding current can take in particular the following values 79mA (80mA - 1 mA) or 81 (80mA +1 mA). Thus, the setting step of 1% reduced to a value of the holding current equal to 80 mA, sets the accuracy level of adjustment of said holding current to ± 1.25% of the fixed initial value.

In addition, according to a second example of application, the holding current can be set to a second initial value equal to 20 mA (in the case of a worn contactor). According to this example, the first voltage step then sets a first intermediate current value equal to 40mA (2% of 2A) and the second voltage step-down secures a second initial holding current value equal to 20mA (50%). A variation of the holding current of plus or minus 1% corresponds to a variation of plus or minus 0.4mA. In other words, given the value of the setting step equal to 1%, the holding current can take in particular the following values 19.6mA (20 mA - 0.4mA) or 20.4mA (20mA + 0.4mA). Thus, the setting step of 1% reduced to the value of a holding current equal to 20 mA, sets the precision level of adjustment of said holding current to ± 2% of the initial value fixed.

These levels of precision are higher than those obtained with known feed means.

Depending on the level of wear of the fixed and moving contacts, the pole springs 5 will be more or less compressed and the force provided by the actuator 1 will be more or less important. Indeed, the less the contacts 20, 21 are worn, the more pole springs 5 are compressed and therefore the force provided by the actuator 1 to compress these springs must be important. Therefore, it is possible to correlate the level of wear of the contacts with the force provided by the actuator for compress the pole springs 5. The figure 2 schematically shows the force profile provided by the actuator 1 during the total opening / closing stroke Ct performed by the movable armature 11 relative to the fixed yoke 10. Considering the opening stroke, the portion A of the profile of the figure 2 shows the force provided by the actuator 1 to go against the pole springs 5 and thus to crush the movable contacts 21 against the fixed contacts 20. According to the level of wear of the contacts, the maximum force provided by the actuator 1 will be different and will be even weaker as the contacts are worn. At the opening, from the point X corresponding to the moment when the contacts open, the force supplied by the actuator 1 becomes weaker since it then consists solely in going against the return spring 4. This effort decreases gradually until the full opening of the contacts. Curve C represents the force profile provided by the actuator when the contacts are worn.

According to the invention, the control current which is injected into the control coil 3 when the mobile armature 11 separates from the fixed yoke 10 is therefore representative of the minimum force provided by the actuator 1 to maintain the armature mobile 11 in the closed position and fight against the pole springs 5. The control current measured at this time can be treated to detect the wear of the contacts or to optimize the operation of the device.

Current measuring means 7 may be added to the various preferred embodiments to allow more precise closed-loop regulation of the currents flowing through the control coil 3. The control means 2 comprise means 7 for measuring the control current i1 in the control coil 3. As described in the patent application of the applicant entitled "Switched electrical device with optimized operation", the control means 2 comprise means for determining a level of wear of the fixed contacts. and movable from the control current i1 during the separation of the moving armature 11 with respect to the fixed yoke 10. In order to determine the level of wear of the contacts, the current i1 which is measured by the measuring means 7 can for example be compared by the control means 2 to different predetermined thresholds recorded in the device to deduce a level of wear of the contacts or compared to the current measured during the previous operation to follow its evolution. It is also possible to convert the measured current i1 into a percentage of wear and to compare this percentage with different thresholds. Other modes of treatment can of course be considered.

According to the invention, by measuring the current by the measuring means 7 during the separation of the moving armature 11 with respect to the fixed yoke 10, the control means 2 can also determine an optimal control current of maintenance to apply to the actuator 1. Usually, the holding current applied to the actuator 1 is chosen sufficiently large that the movable armature 11 can remain in the closed position regardless of the number of optional additives added to the device , the intensity of the shocks or vibrations experienced by the device or the wear of the device. This current is therefore often chosen more important than necessary to take into account these different situations.

The current measured i1 during the separation of the moving armature 11 relative to the fixed yoke 10 can therefore be processed to readjust the holding current and determine an optimum holding current that is adapted to the environment and the configuration of the the device. The current measured during the separation of the mobile armature 11 is for example increased by a determined percentage to ensure that it is sufficient for the maintenance of the armature 11 in the closed position in its environment and in its configuration. Determination of the optimal holding current may be performed at regular intervals to take into account possible additions of additives or environmental change. This functionality can be provided alone in the electrical apparatus or implemented in addition to the wear detection of the contacts. In particular, it makes it possible to optimize the energy consumption of the apparatus by injecting a control current just necessary for maintaining the mobile armature 11 in the closed position.

The regulation means 50 according to the embodiments of the invention are able to precisely control a holding voltage% u supplied to the control coil 3.

• détection de la séparation de l'armature mobile 11 par rapport à la culasse fixe 10,
• mesure du courant de commande i(t) traversant la bobine de commande 3 lors de la séparation de l'armature mobile 11 par rapport à la culasse fixe 10,
• traitement du courant de commande mesuré i1 en vue de commander l'appareil ou d'effectuer un diagnostic de l'appareil.

The Applicant's patent application entitled "Apparatus electrical switch optimized operation "further describes a control method comprising the following steps of:

• detecting the separation of the moving armature 11 with respect to the fixed yoke 10,
• measuring the control current i (t) passing through the control coil 3 during the separation of the mobile armature 11 with respect to the fixed yoke 10,
• processing of the measured control current i1 in order to control the apparatus or to make a diagnosis of the apparatus.

The actuator according to the embodiments of the invention is particularly effective in terms of reducing electromagnetic disturbances of the EMC type.

Preferably, the use of control means adapted to modulate the voltage applied to the control coil 3 according to PWM type pulse width modulation tends to generate EMC type disturbances. As shown on the figure 9 , the control coil 3 undergoes very strong variations of the electric current for very short times (di / dt) and acts as a radio transmitter.

During the holding phase, the PWM type modulation setting is necessarily low in order to generate a low current in the control coil 3. The voltage applied to the coil can be expressed with the following formula: $$\mathit{U}\mathit{=}\mathit{RI}\mathit{+}\mathit{The}\frac{\mathit{di}}{\mathit{dt}}$$

With L the inductance of the control coil 3, U the voltage applied across said coil, R the resistance of said coil

Thus, the instantaneous variation of the electric current during very short times (di / dt) can be expressed with the following formula: $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{\mathit{U}\mathit{-}\mathit{RI}}{\mathit{The}}$$

During the holding phase, the value of the product of the resistance by the current RI is very small compared to the voltage U applied to the control coil 3. Indeed, as an example of application, if the voltage of the call is equal to 340 volts (U = 340V) and if the PWM type modulation setting is 2%, the current resistance product RI is equal to 6.8 volts (RI = 2% x U) .

In an application of known type, the term RI is then negligible compared with that of U and the ratio di / dt can be expressed with the following formula: $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{\mathit{U}}{\mathit{The}}$$

For example, by way of example: $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{340}{\mathit{The}}$$

soit $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{12-6,8}{\mathit{L}}$$

soit $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{5,2}{\mathit{L}}$$

In an application according to one embodiment of the invention as shown in the figure 10 the call voltage U is reduced by the first voltage step-down. By way of example, the call voltage equal to 340 V is reduced to 12V. If the setting of the PWM type modulation is equal to 56%, the resistance product by the current RI is also equal to 6.8 Volts (RI = 0.56 x 12 = 6.8 V) but is no longer negligible vis-à-vis the voltage U. The ratio di / dt can be expressed with the following formula: $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{\mathit{U}\mathit{-}\mathit{RI}}{\mathit{The}}$$

is $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{12-6,8}{\mathit{The}}$$

is $$\frac{\mathit{di}}{\mathit{dt}}\mathit{=}\frac{5,2}{\mathit{The}}$$

In conclusion, for the same control coil 3, by comparing the ratios di / dt obtained in a known application and in an application according to one of the embodiments of the invention, there is a very strong reduction, including a reduction of the CEM emission of a value equal to 65 (340 / 5.2 = 65).

Claims (10)

An electromagnetic actuator (100) comprising: a magnetic circuit (1) comprising a magnetic yoke (10) collaborating with a movable armature (11) controlled in movement between an open position and a closed position, at least one control coil (3) for generating a magnetic flux for moving or holding the moving armature (11) with respect to the magnetic yoke (10) control means (2) for supplying the control coil (3) with: a call voltage (U) during a closing operation of the actuator, and a holding voltage (% u) during a maintenance operation of
the actuator in the closed position; actuator characterized in that the control means (2) comprise holding voltage regulating means (% u) comprising: - a first voltage step down (51, 54, 56) of the call voltage (U) to provide an intermediate voltage (u) lower and proportional to the call voltage (U); - a second voltage step-down (52, 55, 57) of the intermediate voltage (u) for providing a lower holding voltage (% u) proportional to the intermediate voltage (u). Electromagnetic actuator according to Claim 1, characterized in that : The first voltage step-down device (51) is intended to generate a fixed intermediate voltage (u), - The second voltage step (52) is intended to generate a variable holding voltage (% u) proportional to the intermediate voltage (u) fixed. Electromagnetic actuator according to Claim 2, characterized in that the second voltage step-down (52) comprises means for modulating the intermediate voltage (u) fixed according to PWM type pulse width modulation. Electromagnetic actuator according to Claim 1, characterized in that : the first voltage step-down device (54) is intended to generate a variable intermediate voltage (u), the second voltage step-down device (55) is intended to generate a holding voltage (% u) that is fixed and proportional to said variable intermediate voltage. An electromagnetic actuator according to claim 4, characterized in that the first voltage step (54) comprises means for modulating the call voltage (U) according to PWM pulse width modulation. Electromagnetic actuator according to Claim 1, characterized in that : the first voltage step (56) is intended to generate a variable intermediate voltage (u), the second voltage step-down device (57) is intended to generate a variable holding voltage (% u) proportional to said variable intermediate voltage. Electromagnetic actuator according to Claim 6, characterized in that the first voltage step-down (56) comprises means for modulating the call voltage (U) according to PWM-type pulse width modulation and that the second step-down step voltage generator (57) comprises means for modulating the intermediate voltage (u) variable according PWM pulse width modulation. Electromagnetic actuator according to one of the preceding claims, characterized in that the control means (2) comprise means (7) for measuring the control current (i1) in the actuating coil (3) and means for determining a wear level of the fixed and moving contacts from the control current (i1) during the separation of the moving armature (11) relative to the fixed yoke (10). Electromagnetic actuator according to Claim 8, characterized in that the control means (2) comprise means for determining, as a function of the level of wear of the contacts, an optimum control current for the maintenance of the mobile armature (11). in the closed position, the regulating means (50) controlling a holding voltage (% u) supplied to the control coil (3). Switching type electrical switch device comprising an electromagnetic actuator (100) according to one of the preceding claims, characterized in that it comprises a movable member able to move between an open state and a closed state, said member carrying at least one movable contact (21) with respect to a fixed contact (20) for controlling an electrical circuit.

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