WO2004025818A1

WO2004025818A1 - Electronic control device for motor

Info

Publication number: WO2004025818A1
Application number: PCT/FR2003/002723
Authority: WO
Inventors: Thierry Garcia; Jean-Yves Giroux; Alain Krzywdziak
Original assignee: Fillon Investissement
Priority date: 2002-09-16
Filing date: 2003-09-16
Publication date: 2004-03-25
Also published as: JP2005539472A; FR2844650B1; FR2844650A1; AU2003283470B2; CN1682426A; CN1682426B; EP1540805A1; AU2003283470A1

Abstract

The invention relates to an electronic control device for an asynchronous, single-phase or three-phase motor, comprising an electronic board (2) and a relay (3) for controlling the power supply to the motor. The aforementioned electronic board (2) comprises at least one microcontroller (7) which analyses the electric parameters of the electric network, such as frequency and voltage, in order to ensure that said parameters are compatible with the correct operation of the motor and to control the relay (3) which is positioned on the motor power supply network. The board (2) and relay (3) are preferably housed inside a casing (1). The inventive device is characterised in that the relay (3) is a static relay and in that the electronic board (2) also comprises: a capacitive impedance (4) which is powered from the motor power supply network and which is used to lower the supply voltage for the rest of the device and at least one commutation element (5) which is used to start and/or stop the device and which can be controlled via a control element (6) which is in turn controlled by a preferably-manual displacement control. The invention can be used to control single-phase or three-phase motors.

Description

Electronic engine control device

The present invention relates to an electronic control device for a motor, preferably asynchronous, single-phase or three-phase, comprising at least one electronic card and a static relay for controlling the power supply to the motor, card and relay being preferably housed inside 'a housing.

The control devices of the aforementioned type can be adapted both in standard environments or at risk of explosion, but are more particularly used in explosive atmospheres of all kinds, gas or dust, for explosion-proof electric motors of non-limiting type LEROY -SOMER, ELNOR or ATAV (registered trademarks). Such motors are notably widely used for controlling paint agitators or other products containing volatile compounds, an example of the most common risk class of which is IIB T4.

For a long time, these engine control devices were based essentially on mechanical principles, as illustrated in particular by patent EP-A-0.091.360.

Likewise, document US-A-6,150,792 describes a phase controller intended for a three-phase asynchronous motor. In this document, it is intended to supply the motor exclusively with a current whose electrical parameters, frequency and voltage, are in accordance with correct operation of the motor. To solve this technical problem, the means implemented require the presence of an electromagnetic relay associated with a power switch whose drawbacks: high consumption and power and formation of sparks at each switching are well known. Thus, in this phase control, a switch is closed to allow the supply of a first sensor which detects the voltage and frequency conditions of the current and controls, when the conditions are favorable, the supply of the motor by closing the electromagnetic relay and switching the power switch, a second detection system more sensitive than the first detection system and acting with delay relative to this first detection system again detects the frequency and the voltage of the current supplied. This second system is then likely to trigger the opening of the relay and the power switch when the current supply conditions are unfavorable. However, electromechanical relays of the type mentioned above have many drawbacks compared to an electronic control device.

Furthermore, document EP-A-1,079,509 describes a current supply device in which three capacitors arranged in series are provided which thus form a capacitive impedance supplied from the motor supply network, this capacitive impedance serving to lower the supply voltage of the rest of the device. This capacitive impedance is used to supply a led. A photodetector also sends a signal to a microprocessor depending on the state, on or off, of the LED. When the LED is on, the microprocessor, alerted by the photodetector, ensures the polarization of the transistor which then becomes conductive and supplies an electromagnetic relay which thus allows a supply of the motor. When a fault appears on the input current, the LED goes out, the photodetector signals the extension of the LED to the microprocessor which then opens the electromagnetic relay preventing any supply of the motor. Again, the essential drawback of such a device is linked on the one hand to the presence of an electromagnetic relay necessarily involving damaging mechanical contacts in the context of installations intended for environments at high risk of explosion. The presence of at least three capacitors shows that the intensity necessary for the control is important because of the type of control elements selected.

Then, electronic type orders gradually appeared on the market to respond to the technological development of products. Several electronic control technologies compete in standard or explosion-proof motor control applications and, in this context, differ according to the nature of the electronic control in wired or programmed logic, the means used for switching the power of the electromechanical dry contact relay type or static relay with electronic thyristor contact, the start and stop control elements, the protection and safety modes necessary to guarantee the absence of electrical risks in all circumstances and in particular of risks of explosions in potentially explosive atmospheres European directives and harmonized standards in force.

The examples below illustrate achievements based on the criteria mentioned above.

A number of engine controls are directly offered by engine manufacturers, particularly in the USA such as FRANKLIN or

RELIANCE. The electronic control with programmed logic is deported via an electrical connection cable in a compact and light plastic housing. The connecting cable at its other end is connected to the motor terminal box in which the switching of the power is necessarily placed, which is mainly carried out by relays which may be of the electromechanical or static type. The engine start and stop are controlled by a keyboard with flexible membranes for tactile buttons. The electrical safety elements in potentially explosive atmospheres are ensured by the association of the modes “d” of explosion-proof enclosure for the motor and “i” of intrinsic safety for the electronic card and its remote control elements.

This control device has the drawback of being inextricably linked with a type of motor which exclusively has suitable connection means. This proprietary "engine and electronic control" assembly is not universal and cannot be recovered for another commercial engine if it is not provided for this purpose. A number of other motor controls are offered by manufacturers of electrical components such as LEGRAND ATX, TECHNOR or BARTEC. These do not have electronic control, but are made up only with standard electrical components such as power discontactors and motor protection relays capable of absorbing very high intensity currents of the TELEMECANIQUE electrical component type assembled in an envelope explosion-proof "d" associated with electrical contact push-buttons for on / off control in an analogous protection mode or in increased safety mode "e" described by standard EN50019. The box is then connected to the motor by appropriate electrical cables.

These electrical control devices present in the catalog of large manufacturers of electrical equipment for motors in explosive atmospheres have the disadvantage of being prohibitively expensive despite basic all-or-nothing operating functions only, of considerable bulk and '' excessive weight due to a very thick aluminum or plastic enclosure type “d” to meet safety requirements. Consequently, these solutions are not economically satisfactory since they cannot be optimized due to the fact that the basic model incorporates accessory characteristics to avoid investments of heavy tools in the production of the housings. In addition, all approvals are dedicated to a single technical application and cannot be generalized to another. This type of device, to be composed according to its need in the catalogs of distributors, is available immediately on the market, but turns out to be of unacceptable use for paint stirring machines whose overall cost must always be reduced.

This is why, more recently, in the very specific field of paint stirrers, the companies FAS and FILLON-PICHON have developed their own motor control solutions which are much more economical and can be adapted to both explosion-proof and standard motors. Thus, two innovative versions of original electronic controls and high performance then emerged from 1995 on the world market of paint stirrers intended for the repair of automobile bodies.

The electronic control version of FAS includes a very compact wired logic electronic card on which all of the electromechanical relay type power control and switching components are installed. It can be integrated either in a standard plastic enclosure or in an explosion-proof aluminum enclosure specific for use in an explosive atmosphere in accordance with standard EN50018. The engine is started and stopped by touch buttons on a flexible membrane keyboard. An amperometric protection element ensures motor safety. Another alternative solution is to house all of the electronics in the motor terminal box and to deport only contactors such as pushbuttons with electrical contact, possibly in protection mode "d" for potentially explosive atmospheres. The electronic control version of FILLON-PICHON comprises, housed inside a housing, at least one electronic card in programmed logic and a power switching component of the CELDUC static relay type to control the power supply of the motor. The engine is started and stopped by touch buttons on a flexible membrane keyboard. The general rules, described in the European standard EN50014, are applied for protection in an explosive atmosphere and more particularly that of encapsulation "m" (standard EN50028) with a resin of polyurethane or Epoxy type in combination with that of intrinsic safety. "I" (standard EN50020).

In these two versions, the electronic cards have at least one transformer technology to be soldered on an electronic circuit connected by the phase wire of the alternating network supplying the motor to the mains. The function of this transformer is to lower the line voltage to draw the energy required to supply a regulator which will restore it in the form of a DC voltage of a few volts which will be used exclusively for the control unit. This transformer is protected upstream by fuse type components for overcurrents or varistor type for overvoltages.

These different personalized control devices have various drawbacks.

Indeed, it is not possible to make a transformer with a reduced bulk which can both withstand high maximum input voltages without the risk of overheating and ensure a very wide network voltage range.

For the first point, a transformer, even when empty, consumes energy and heats up. Excessively high voltages close to or greater than 250 volts aggravate overheating and lead to irreversible damage to the component.

For the second point, the very construction technology of a transformer implies a dependence relationship with a constant established transformation ratio "r _t ", corresponding to the relationship between the number of winding turns ni on the primary and n ₂ on the transformer secondary such as:

U2 / U- _I = li / b = n ₂ / n-ι = r _t .

With:

Ui and primary voltage and current respectively. U ₂ and l ₂ respectively voltage and current at the secondary.

Under these conditions, the search for an acceptable compromise requires oversizing the transformer with, for the requirements of standard EN50028 relating to the “m” encapsulation protection mode, the addition of a hot-melt to control the temperature. In all cases, special manufacturing must be carried out at significant cost.

In addition, the existing transformers corresponding to the best performance achieved has an operating range that is still too narrow to meet the requirements of all networks around the world with their wide tolerance. This results in the need to have at least two types of transformers and to adapt, each time, the control device to the network of the country in which such a control device is to be installed. In addition, depending on the importance of this voltage range, it is necessary to carry out a lowering of a voltage up to a value always usable by the regulating component responsible for supplying with DC voltage the control components of the electronic circuit. .

In addition, the fact of having on the one hand a bulky transformer on an electronic card itself clipped in height on an aluminum plate and on the other hand, the independent assembly of a standard static relay component arranged inside a housing on the same plate made of aluminum sheet for its heat dissipation, generates a very large, relatively bulky set. At the same time, this assembly must be embedded inside a protective material such as a resin in order to isolate all the electrical parts of an explosive atmosphere zone in accordance with the construction requirements of the "m" mode of encapsulation. A covering height of 3 mm is then imposed not only above the highest component, but also around the electrical components. The large size inevitably generates a large consumption of resin resulting in an additional cost of the control device.

In addition, the assembly of several independent electrical sub-assemblies by means of connection panels, solder or crimp terminals, added welds or added shunts involves a significant preparation time and a complex manufacturing process that 'it is difficult to master. The guarantee of a product's durability over time is no longer absolute, despite all the care given to the numerous quality controls at all stages of industrial manufacturing. In fact, the risk of failure can occur after a period of abnormal transport or use of the product in extreme environments. Finally, the use of control members of the type made up of a membrane keyboard generates a certain number of failures over time, such as the rupture of the electrical connection ply during an excessive expansion of the resin or the blocking of touch buttons under the effect of excessive ambient temperature. Such a system ultimately requires reinforced choices in materials and very severe industrial control becoming very costly to manage for an unsuitable or ill-prepared activity. In addition, any electrical element such as a control keyboard to be placed outside the encapsulation zone, that is to say in the dangerous zone at risk of explosions, entails the use of a Zener barrier. downstream of the transformer. This component will limit the energy of the external electrical components to avoid creating sparks. This consists in particular of a fuse.

Similarly, the electronic card is secured by means of fuse-type members which prevent any improper connection or any starting of the engine in the event that the conditions required and necessary for the proper functioning of the engine are not met. However, such elements of the fuse type being embedded in the resin, when they are triggered, the control device becomes unusable because there is no possibility of resetting.

An object of the present invention is therefore to propose a control device of a new type, the design of which makes it possible to limit the overall size of the assembly, to eliminate all types of components which are sources of failure under the most severe conditions such as transformers or flexible membrane keypads, which today have a certain number of drawbacks and have efficient management of electrical safety, no longer requiring the incorporation of irreversible elements, such as fuses or varistor, in the insulating material. Another object of the invention is to propose a control device incorporating permanent intelligent monitoring by means of a microcontroller capable of prohibiting the starting of the motor in the event of a minimum or maximum fault voltage likely to cause destruction. of the electric motor.

Another object of the invention is to provide a reliable control device by rationalizing the electrical connections by eliminating the strips on the electronic card.

An ^other object of the invention to provide a capable of withstanding temperatures controller elevated to 50 ° C under normal conditions of use with a degree of relative humidity higher than 95%.

Another object of the present invention is to provide a control device whose design allows safe operation in an explosive atmosphere of gas type "G" mainly using the protection mode "m" encapsulation considered to be the simplest. and the most economical, in particular due to the possible use of a standard plastic case, in combination with the "i" mode of intrinsic safety if necessary for components external to the encapsulated area. In addition, the complete encapsulation of the electrical parts allows use in dust-type environments "D" (Dust) much more restrictive and imposing a protection index at least equal to IP 65.

Another object of the invention is to standardize a single motor control whatever the asynchronous motor used of standard or EX type.

Another object of the present invention is to provide a control device offering possibilities of operation within extended voltage ranges in order to overcome the problems of very great diversity in highly heterogeneous global electrical networks. To this end, the subject of the invention is an electronic control device for a motor, preferably asynchronous, single-phase or three-phase, comprising at least one electronic card and a relay for controlling the power supply to the motor, the electronic card comprising at least one microcontroller analyzing the electrical parameters of the sector, such as frequency and voltage, to ensure that they are compatible with correct operation of the motor, in order to control the relay positioned on the motor supply network, card and relay being preferably housed inside a box, characterized in that the relay is a static relay and in that the electronic card further comprises:

a capacitive impedance supplied from the motor supply network and used to lower the supply voltage of the rest of the device, and

- At least one switching device for starting and / or stopping the device controllable by means of a control member, itself controlled by a displacement control, preferably manual.

The replacement of a transformer by a capacitive supply and the intelligent management obtained by means of a microcontroller make it possible to obtain a control device of small size, of perfectly safe operation and in particular stable over time.

According to a preferred embodiment of the invention, the assembly of the electronic card and the static relay is embedded in a block of insulating material, such as a resin.

According to another preferred embodiment of the invention, the assembly of the electronic card and the static relay is housed in an envelope of type "d", such as an aluminum envelope constituted in particular by the motor terminal box .

The switching member or members consist of flexible-blade switches which can be controlled preferably by magnets. The invention will be clearly understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which:

FIG. 1 represents a perspective view of a control device according to the invention in the exploded position of the elements constituting it and

2 shows a sectional view of a control device according to the invention.

The device, object of the invention, has the function of allowing electronic control of a motor, preferably asynchronous, single-phase or three-phase, intended in particular to be used in potentially explosive atmospheres.

This device is preferably housed inside a box 1, preferably made of insulating plastic, antistatic and generally comprises an electronic card 2 and a static relay 3 to control the supply of the motor and authorize or not the latter depending on the characteristics of the sector.

Characteristically to the invention, the electronic card 2 comprises a capacitive impedance 4, switches 5 with a blade controllable by means of magnets 6 and push-buttons 12 and a microcontroller 7. The control device is powered at from the motor supply network, it is connected to the phase wire itself connected to the mains. The voltage of this network can vary from 70 to 260 volts single phase with the risk of connection in 400 volts three phase for a frequency of 50 or 60 Hertz.

To allow the device to control the supply of the motor from this AC network, it is therefore necessary to lower the voltage and obtain a voltage of low continuous value to supply all the logic of the electronic card 2. The solution chosen, unlike the prior art where a transformer is used to lower the supply voltage, is made up of a capacitive impedance 4. This capacitive impedance 4 consists of two capacitors, preferably plastic, in series. This capacitive impedance 4 is, for example in the case of a supply of a single-phase motor, consisting of two capacitors in series with a capacity of 1 μF of type X2 275 VAC with dimensions equal to 23 x 20 x 9 mm which allow operation without overheating, including at high voltages of the order of 260 volts. Because of a very low control intensity of less than 10 mA in our application case, this results in the possibility of using the smallest capacitors of very small size in this technology for a minimum resin volume. These capacitors are nevertheless capable of operating at 2/3 of the maximum power of the components in accordance with the electrical safety requirements in Explosive Atmosphere defined by the standards in force which impose a temperature rise limit at the maximum use voltage value.

The doubling of the capacitive value of a capacitor, which would generate a higher intensity, is accompanied by an exponential increase in its volume. In addition, the lower intensity consumed favorably leads to greater optimization of the volume. The same reasoning can be adopted for an increase in the number of capacitors resulting from a higher current demand.

This capacitive impedance is connected in the case of a single-phase motor to the phase wire of the motor and thus makes it possible to lower the supply voltage of the device to a value less than 25 volts. Between impedance 4 and neutral is inserted a diode rectifier bridge which delimits a rectified voltage to a precise value of 5 volts. Other capacitors can be positioned on the circuit downstream of this bridge to ensure smoothing of the current and short-circuit any residual AC voltage. The objective is therefore to obtain, by means of this plurality of components, a direct voltage of a value of the order of a few volts, this voltage being used in particular for supplying a microcontroller 7 of the PIC 16C620 type. . This microcontroller 7, also carried by the electronic card 2, analyzes the electrical parameters of the sector such as frequency and voltage to ensure that they are compatible with correct operation of the motor in order to control the static relay 3 positioned on the network d motor power, in particular on the motor phase wire. This static relay 3 has the function of authorizing or not the passage of the current used to supply the motor as a function of the characteristics of the current supplied by the sector. The microcontroller 7 also has the function, in certain cases, of determining the operating time of the engine.

The ^' microcontroller 7 has above all a preponderant role in the functions of monitoring the electrical quantities input on the electronic card. Indeed, it exercises permanent control of the power supply parameters so as not to authorize the control of the static relay or trigger the electrical safety devices upstream of the installation.

The purpose of monitoring is to adjust the voltage threshold parameters to secure the motor within the fixed limits (fault detection and restitution of information, relay timing, etc.) or other intelligent logic functions

For this, an analog or comparator type input from the microcontroller is used to analyze the parameters necessary for monitoring.

The lowering of the power supply is achieved by a capacitive impedance depending on the frequency with the relation:

• Ur = read / Z c with Zc = 1 / (C _eq, 2.π.f)

• Ur is read / (C _eq ..2.π.f).

Consequently, the voltage will be different depending on the frequency. Frequency monitoring makes it possible to identify the line voltage (indirectly by measuring the lowered voltages) and to control the minimum voltages and maximum threshold at which the microcontroller will give the order to prohibit starting the engine.

The device is switched on and off by switches 5 with flexible blades which can be controlled by push-buttons 12 and magnets 6. The push-buttons 12 could be replaced by any other control to displacement, preferably manual, the push-button solution remaining a preferred solution for the targeted applications. To meet the safety standards required in the case of explosive environments, the whole of the electronic card 2 and the static relay 3 is encapsulated, that is to say embedded in a block 8 of insulating material, such as a resin. The small size of the capacitive impedance 4 and the arrangement of the static relay 3 with respect to the electronic card make it possible to obtain an assembly of small size limiting the amount of insulating material to be used.

The definition of encapsulation is a method of applying a compound of the Epoxy or Polyurethane resin type to enclose one or more electrical device (s) by suitable means such as coating or potting. Likewise, the coating is a process for completely coating an electrical device (s) consisting in pouring a compound onto it, and removing the enclosed device from the mold after the compound has solidified. Potting, on the other hand, is a coating process in which the mold remains attached to the enclosed electrical device (s). The encapsulation process used is therefore a potting process in which, after the pouring of the insulating material, the mold remains attached to the enclosed electrical device. It therefore differs from the coating technique in which the electrical devices are, after an insulating material has been poured into a mold, removed from the mold. A resin height of the order of 26 mm is thus obtained for a height of the electronic card and of the static relay corresponding to only about 8 mm. In this configuration, the device comprises at least two flexible blade switches 5 carried respectively by cradles 11 so as to be close to the surface of the block 8 of insulating material in order to authorize their control and ensure remote switching from a distance or proximity without electrical contact such as by magnets 6. An equivalent version would have consisted in removing the insulating material and in housing the assembly in a envelope of type "d".

A possible variant without this calling into question the technological choices of an encapsulated electronic card would be to deport the control member while ensuring its protection by encapsulation "m" or by combination with another mode of intrinsic safety type " i ”or flameproof enclosure“ d ”. Thus, one can easily imagine a remote sensor outside the encapsulated area of the electronics, the preferably encapsulated control member of which is itself controlled by a manual or automatic displacement control.

The static relay 3 comprises at least one thyristor 3A, preferably two thyristors positioned head to tail, welded to a plate 10 of conductive material, such as aluminum, serving as a heat sink adapted to the case of use and customized to ensure sufficient heat exchange in the smallest possible space to prevent overheating. Thus, the support plate 10 has a "U" shape for a thickness of 1.5 mm in order to offer the greatest dissipation surface. The assembly is thus housed in a box 1 which comprises: - a bottom 1A containing the block 8 of insulating material in which the electronic card 2 is embedded the static relay 3 and its heat sink - and a cover 1B intended to be fixed to the bottom 1A by snap-in without using a tool.

The arrangement of the thyristor (s) on a plate 10 of conductive material makes it possible to first position this plate at the bottom of the housing and then to superimpose on this plate the electronic card comprising all of the other elements mentioned above which will then be bonded by welding. Once the assembly in position, it can then proceed to the pouring of the insulating material inside the housing in order to encapsulate the various elements. As defined above and in accordance with standard EN 50028, when the electrical equipment is encapsulated, the encapsulated part of electrical equipment or the encapsulated Ex component includes a protective envelope made of insulating material (potting), it is not required to be thick minimum layer between the protective envelope and any component or conductor if the thickness of the envelope is at least 1 mm. Therefore, the optimization of the volume of resin was increased by a thickness of the casing of the housing of at least 1 mm. Thus, the heat sink is placed directly in contact with the bottom of the housing.

To allow the starting and stopping of such a device, there are provided, as mentioned above, magnets 6 cooperating with switches 5 with a flexible blade. These magnets 6 are each carried by a push button 12 loaded by spring 14 and incorporated in the cover 1B of the housing 1. One of the push buttons 12 is used for commissioning the device while the other is used for the shutdown of the device. These flexible blade switches more particularly authorize the operation of the microcontroller 7.

As mentioned above, the electronic card is directly supplied by the motor supply network. To this end, the assembly is positioned on the phase wire of the motor in the case of a single-phase motor. Thus, the control device can be supplied from the motor supply network after lowering the supply voltage by means of the capacitive impedance. This capacitive impedance makes it possible to receive voltages which can vary over a wide range, in particular from 70 to 260 volts with frequency values which can vary between 50 and 60 Hertz. Once the voltage is lowered between 8 and 25 volts, the microcontroller 7 analyzes the electrical parameters of the lowered voltage and the frequency and defines by extrapolation the values of the input voltage so as not to authorize the control of the static relay when this voltage is outside a predetermined range to prevent damage to the motor. The static relay is also positioned on the phase wire of the motor in accordance the obligation of electrical safety standards indicating the interruption of all phases.

To allow a ready-to-assemble assembly to be obtained, the bottom 1A of the housing has a chamber for the supply of cables from the sector and the departure for cables from the motor separated from the block 8 of insulating material by a partition 13. This partition , in the vicinity of its upper edge, a plurality of notches facilitating the wedging of the cables. This box is also fitted with cable glands through which cables connected to the mains and those to the motor are introduced. In a more elaborate variant, it is possible to envisage deporting the connection to a terminal block outside the encapsulated zone, but remaining inside the envelope, in order to allow a wiring option independent of the electronic unit. For reasons of protection in Explosive Atmosphere, this terminal block must be protected according to the increased safety mode "e". This mode implies in particular that the envelope is waterproof with a protection index at least equal to IP 54. The housing has, for this purpose, a channel around its periphery in order to be able to possibly receive a sealing means such as '' a flexible seal guaranteeing the required degree of protection.

Finally, to ensure permanent monitoring of the operation of the device, the electronic card 2 carries a two-color diode 15 projecting from the insulating block 8. This diode 15 is capped with a light guide 16 coupled to the cover 1B of the housing 1 so as to make visible, from outside the housing 1, the light signal emitted by the diode 15. Any failure can thus be viewed in time real and continuous. Likewise, the control of the static relay in real time and continuously prevents any passage of the current towards the motor when the current does not meet the characteristics allowing satisfactory operation of the motor.

To facilitate positioning of the housing 1 on any support, the bottom 1A of this housing 1 can be provided with elastically deformable tabs 9 cooperating with the support. The operation of such a control device is very simple. Once the connection has been made, on the one hand to the motor, and on the other hand to the sector, the device can be started by simply pressing the push button corresponding to the commissioning of the device. This actuation of the push button allows the magnet fitted to a push button to attract a strip fitted to a switch 5 with a flexible blade, such as a REED bulb so as to close the contact. The microcontroller 7 can then be supplied with low value direct current via a rectifier bridge ensuring the regulation of 5 volts downstream of the capacitive impedance and analyzing the ^' electrical parameters of the sector. In the case where the voltage supplied is compatible with correct operation of the motor, this microcontroller 7 controls the static relay 3 and authorizes the latter to let the current flow towards the motor. The motor can then operate for a generally predetermined duration corresponding to that programmed in the microcontroller 7. After the predetermined period of time has elapsed, the motor is automatically stopped. In the event of an emergency stop, the other push button can be actuated in order to stop the engine.

In the case of a three-phase motor, each phase wire of the motor is fitted with a static relay 3.

Claims

1. Electronic control device for a motor, preferably asynchronous, single-phase or three-phase, comprising at least one electronic card (2) and a relay (3) for controlling the power supply to the motor, the electronic card (2) comprising at least one microcontroller (7) analyzing the electrical parameters of the sector, such as frequency and voltage, to ensure that they are compatible with correct operation of the motor, in order to control the relay (3) positioned on the motor supply network , card (2) and relay (3) being preferably housed inside a housing d). characterized in that the relay (3) is a static relay and in that the electronic card (2) further comprises:

- a capacitive impedance (4) supplied from the motor supply network and used to lower the supply voltage of the rest of the device, and

- at least one member (5) for switching on and / or off the device controllable by means of a control member (6), itself controlled by a displacement control, preferably manual .

2. Device according to claim 1, characterized in that the assembly of the electronic card (2) and of the static relay (3) is embedded in a block (8) of insulating material, such as a resin.

3. Device according to claim 1, characterized in that the assembly of the electronic card (2) and the static relay (3) is housed in an envelope of type "d", such as an aluminum envelope.

4. Device according to one of claims 1 to 3, characterized in that the member (s) (5) switching consist of switches (5) flexible blade controllable preferably by means of magnets (6) .

5. Device according to one of claims 2 and 4, characterized in that it comprises at least two switches (5) with flexible blade carried respectively by cradles (11) so as to be close to the surface of the block (8 ) of insulating material to authorize their order by magnets (6).

6. Device according to claim 1, characterized in that the relay (3) static comprises at least one thyristor (3A) welded to a plate (10) of conductive material, such as aluminum, serving as a heat sink.

7. Device according to claim 1, characterized in that the capacitive impedance (4) consists of two capacitors, preferably plastic, in series.

8. Device according to claim 1, characterized in that the housing (1) comprises:

- a bottom (1A) containing the block (8) of insulating material in which the electronic card (2) and the static relay (3) are embedded, - and a cover (1 B) intended to be fixed to the bottom (1A) snap-on without the need for a tool.

9. ^' Device according to claim 8, characterized in that the cover (1 B) of the housing (1) carries two push buttons (12) each carrying a magnet (6) for controlling a switch (5) to flexible blade, one for putting the device into service, the other for stopping it.

10. Device according to claim 8, characterized in that the bottom (1A) of the housing comprises an inlet chamber for the cables from the sector and from the cables for the motor separated from the block (8) of insulating material by a partition (13 ).

11. Device according to claim 8, characterized in that the electronic card (2) carries a two-color diode (15) projecting from the insulating block (8), this diode (15) being capped with a light guide (16) coupled to the cover (1B) of the housing (1) so as to make visible, from outside the housing (1), the light signal emitted by the diode (15).

12. Device according to one of claims 1 to 11, characterized in that the housing (1) is made of antistatic plastic.