EP1209709A1 - Electrical circuit for transmitting the status information, particularly for railway material, and system incorporating such a circuit - Google Patents

Abstract

The equipment state transmission system has a battery (3) and an electrically isolated connection (7) between the electrical circuit and an output (S). A variable voltage (1) adjusts the current in the switch (5) as a function of the voltage generator voltage. There is a self inductive filter (6) in series with the switch and a capacitor (13) which stores and releases part of the energy following the variable voltage generator.

Description

The invention relates to an electrical circuit for routing information of all or nothing type, in particular for an application in the field rail.

In a train, many all-or-nothing signals indicating the state of a parameter or equipment are routed for example to an electronic circuit control systems or to a control and signaling panel. These signals are, for example, representative of the state of a circuit breaker or the position open or closed from an access door to a car and are intended to be routed with a high degree of security and availability, which makes the use of links unsuitable low energy computer type.

A solution currently used consists in connecting to the two terminals of a accumulator an electric circuit in closed loop, which comprises in series at least one switch linked to the state of the organ to be controlled, a resistance, and an insulation link galvanic connected to the device receiving the information contained in the signal, by example the electronic control circuit of the PLC or the control and signaling.

The open or closed position of the switch is representative of the state of a parameter or equipment. When the switch is closed, a current, including the intensity is limited by the resistance, circulates in the circuit. When open, no current does not pass. The presence or absence of this current is transformed by the connection to galvanic isolation into all or nothing information communicated to the electronic circuit.

Generally, a train has a plurality of such circuits connected to terminals of the same accumulator.

As the switches tend to oxidize, a minimum intensity of current, of the order of a few tens of milliamps, must pass through each of these switches to clean them. This current is consumed at a loss in the resistor. Of more, the power dissipated in the resistance by Joule effect produces heat, which must be evacuated. A known solution is to use fans, however, to At the present time, we avoid or even forbid ourselves from using such fans as a mode for cooling electronic circuits on board trains for reasons of reliability, a fan with mechanical components likely to jamming, seizing up and, in general, causing a breakdown.

The reliability of electrical and electronic components decreasing sharply when the ambient temperature increases, we try to produce the least heat possible.

Furthermore, the accumulator generally supplying several circuits, and other equipment, the voltage it delivers varies over time with the level of load at its terminals. The intensity of the current in the circuit therefore also varies, in proportion to the state of charge of the accumulator.

Therefore, to obtain the minimum intensity required for cleaning switches, you have to agree to consume a significant additional current and therefore of power, during certain periods during the operation of the circuit. The additional heat production which accompanies it increases the problem of the evacuation of this heat.

The amount of heat dissipated increases with the number of switches and information to be transmitted.

The invention aims to reduce the aforementioned drawbacks of the prior art.

The aim of the invention is therefore to carry information from all or nothing type with a high degree of reliability and availability, while reducing the power dissipated by the Joule effect.

• une liaison à isolation galvanique entre ledit circuit électrique et une sortie pour l'émission d'une information d'état, et
• un interrupteur dont la position ouverte ou fermée est représentative de l'information d'état et qui détermine le passage d'un courant dans ledit circuit électrique, le circuit électrique assurant la transmission de l'information d'état de l'interrupteur vers la sortie, par l'intermédiaire de la liaison à isolation galvanique,

caractérisé en ce que, pour réguler l'intensité du courant dans l'interrupteur, il comporte des moyens générateurs de tension variable coopérant avec des moyens de commutation pour alimenter sélectivement des éléments constitutifs du circuit électrique en fonction de la tension de sortie des moyens générateurs de tension variable et en ce qu'il comporte des moyens de filtrage selfiques en série avec l'interrupteur et des moyens d'emmagasinage capacitifs qui, en régime établi, forment chacun des moyens de stockage et moyens de restitution d'une partie de l'énergie du circuit électrique, selon la tension de sortie du générateur de tension variable.It therefore relates to an electrical circuit for transmitting the state of a parameter or of equipment, intended to be connected to the terminals of a supply accumulator and comprising:

• a galvanically isolated connection between said electrical circuit and an output for transmitting status information, and
• a switch, the open or closed position of which is representative of the status information and which determines the passage of a current in said electrical circuit, the electrical circuit ensuring the transmission of the status information from the switch to the output, via galvanically isolated link,

characterized in that, to regulate the intensity of the current in the switch, it comprises means for generating variable voltage cooperating with switching means for selectively supplying elements constituting the electrical circuit as a function of the output voltage of the generator means of variable voltage and in that it comprises inductive filtering means in series with the switch and capacitive storage means which, in steady state, each form storage means and means for restoring part of the energy of the electrical circuit, according to the output voltage of the variable voltage generator.

• les moyens de filtrage selfiques sont disposés à proximité immédiate de l'interrupteur;
• une diode est interposée entre l'interrupteur et les moyens de filtrage selfiques, la diode étant polarisée de manière à interdire l'écoulement du courant des moyens de filtrage selfiques vers l'interrupteur ;
• les moyens de filtrage selfiques sont constitués d'une inductance, le circuit électrique comportant en série avec l'interrupteur et l'inductance, des première et deuxième branches en parallèles, et comportant une résistance disposée en parallèle avec l'interrupteur et l'inductance et connectée à un point de la deuxième branche, une capacité étant connectée dans la première branche et les moyens de commutation des connexions comportent une diode connectée dans la deuxième branche entre d'une part, l'une des jonctions des première et deuxième branche, et d'autre part, le point de connexion de la résistance sur la deuxième branche, la deuxième branche comportant également une capacité connectée entre d'une part l'autre de ces jonctions des première et deuxième branches et d'autre part, le point de connexion de la résistance sur la deuxième branche ;
• la liaison à isolation galvanique est connectée en série avec les moyens de filtrage selfiques ;
• la liaison à isolation galvanique est connectée en série avec la résistance ;
• le signal produit par les moyens générateurs de tension est un signal rectangulaire, triangulaire ou sinusoïdal centré ou non sur 0 volt ;
• les moyens générateurs de tension variable sont connectés dans la première branche ;
• la liaison à isolation galvanique consiste en un opto-coupleur ;
• la liaison à isolation galvanique consiste en un transformateur ;
• la liaison à isolation galvanique consiste en un transformateur connecté en série avec l'interrupteur et dont le primaire forme également au moins une partie des moyens d'emmagasinage selfiques ;
• l'entrée de l'interrupteur est branchée à une borne de l'accumulateur et un écrêteur est disposé entre la sortie de l'interrupteur et l'autre borne de l'accumulateur.

According to other characteristics of this electrical circuit:

• the inductive filtering means are arranged in the immediate vicinity of the switch;
• a diode is interposed between the switch and the inductive filter means, the diode being polarized so as to prevent the flow of current from the inductive filter means to the switch;
• the inductive filtering means consist of an inductor, the electric circuit comprising in series with the switch and the inductor, first and second branches in parallel, and comprising a resistor arranged in parallel with the switch and the inductor and connected to a point of the second branch, a capacitor being connected in the first branch and the switching means of the connections comprise a diode connected in the second branch between on the one hand, one of the junctions of the first and second branch, and on the other hand, the connection point of the resistor on the second branch, the second branch also comprising a capacitor connected between on the one hand the other of these junctions of the first and second branches and on the other hand, the point connecting the resistor to the second branch;
• the galvanically isolated link is connected in series with the inductive filtering means;
• the galvanically isolated link is connected in series with the resistor;
• the signal produced by the voltage generating means is a rectangular, triangular or sinusoidal signal centered or not on 0 volts;
• the variable voltage generating means are connected in the first branch;
• the galvanically isolated connection consists of an optocoupler;
• the galvanically isolated connection consists of a transformer;
• the galvanically isolated connection consists of a transformer connected in series with the switch and the primary of which also forms at least part of the inductive storage means;
• the input of the switch is connected to one terminal of the accumulator and a clipper is disposed between the output of the switch and the other terminal of the accumulator.

The invention also relates to an electrical system intended for transmitting a plurality of state information, characterized in that it comprises an accumulator and a plurality of electrical circuits, as defined above, each intended for transmit status information and connected in parallel to the terminals of said accumulator.

According to another characteristic of this electrical system, it is on board a railway convoy, each switch being associated with an organ or a equipment of the railway convoy, to control its state or position.

• la figure 1 représente un circuit électrique pour la transmission d'une pluralité d'informations tout ou rien selon un mode particulier de réalisation de l'invention,
• la figure 2 représente un graphe illustrant la tension de sortie du générateur de tension,
• la figure 3 représente un graphe illustrant la valeur théorique du courant en fonction du temps dans la branche du circuit comportant l'interrupteur, la représentation selon l'axe des ordonnées étant grossie de manière à faire apparaítre de façon accentuée la variation de courant.
• la figure 4 représente une variante de réalisation du circuit électrique de la figure 1.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

• FIG. 1 represents an electrical circuit for the transmission of a plurality of all or nothing information according to a particular embodiment of the invention,
• FIG. 2 represents a graph illustrating the output voltage of the voltage generator,
• Figure 3 shows a graph illustrating the theoretical value of current as a function of time in the branch of the circuit comprising the switch, the representation along the ordinate axis being magnified so as to show in an accentuated manner the variation of current.
• FIG. 4 represents an alternative embodiment of the electrical circuit of FIG. 1.

To facilitate the reading of the drawings, only the elements necessary for the understanding of the invention have been shown. The same elements have the same references from one figure to another.

FIG. 1 represents a particular embodiment of a circuit for transmission capable of transmitting all or nothing information representative of the state of a organ or equipment to be checked, in particular vehicle equipment rail. An elementary circuit belonging to a system has been isolated in FIG. 1 more complete electric, not shown, comprising a plurality of elementary circuits similar connected in parallel to the terminals of an accumulator and able to transmit a plurality of all or nothing information to an electronic circuit for controlling automata.

The electrical transmission circuit is connected to the terminals of a accumulator 3 and a connection S collects at the output of the elementary circuit, the information all or nothing by means of a link which will be described below, to transmit it to one of the input ports of an electronic circuit 2.

The electronic circuit 2 also includes ports 4 for output by example for the control of PLCs (not shown).

In the main application targeted, the accumulator 3, the electrical system and the electronic circuit 2 are intended to be loaded onto a train. It goes without saying that the electronic circuit 2 for controlling PLCs can be replaced by a control panel control and signaling or by any device capable of receiving and processing a all or nothing information.

Generally, the accumulator 3 is the only source of direct voltage for the whole train. Also, the various on-board equipment which requires a supply of direct current are supplied by this single accumulator 3. The voltage which it delivers is therefore likely to vary over time, depending on the load at its terminals, between 0.6 times and 1.4 times its nominal voltage.

The accumulators 3 generally used at present in trains, have nominal voltages of 24 volts, 36 volts, 48 volts, 96 volts and 110 volts.

In accordance with FIG. 1, the electrical transmission circuit comprises a loop B supplied by the accumulator 3 which comprises, arranged in series, a switch 5, a diode 16, an inductor 6, a galvanically isolated connection 7 which can for example be carried out by means of an optocoupler, and two branches 8 and 9 in parallels originating at a point A arranged at the outlet of the connection to galvanic isolation 7. The diode 16 is polarized so as to prevent the discharge of inductor 6 elsewhere than through the optocoupler 7.

For convenience, the following convention is adopted in the continuation of the description: the direction of current flow in loop B of the terminal positive towards the negative terminal of accumulator 3 defines a positive orientation of this loop B.

The branch 8 comprises, arranged in series, a capacitor 10 and a variable voltage generator 1 producing a square signal, of half-period t ₀ and of peak-to-peak amplitude Vg symmetrical as shown in FIG. 2. The value of the voltage amplitude Vg will be chosen to be less than the voltage E across the terminals of the accumulator 3 and will, for example, be of the order of 15 V. w

The second branch 9 comprises a diode 12 and a capacitor 13 in series. A resistor 14 is disposed between a point P of the second branch 9 located between the diode 12 and the capacitor 13, and the positive terminal of the accumulator 3. The diode 12 is polarized so as to prevent the discharge of the capacitor 13 elsewhere than by the resistance 14.

Vd la chute de tension dans chacune des diodes 10,16, avec Vd de l'ordre de 0.5V,

Vled la chute de tension dans la led de l'optocoupleur 7, avec de Vled de l'ordre de 2V,

Vc la chute de tension dans le contact d'entré 5, avec Vc < E,

V_A la tension au point A et V_P la tension au point P.

Les capacités des condensateurs 10 et 13 seront choisies de façon à ce que C₁₃ >> C₁₀, la résistance 14 sera choisie faible.The operation of the electrical circuit will now be described. In the following description we will call by convention:

Vd the voltage drop in each of the diodes 10,16, with Vd of the order of 0.5V,

Vled the voltage drop in the led of the optocoupler 7, with Vled of the order of 2V,

Vc the voltage drop in input contact 5, with Vc <E,

V _At the voltage at point A and V _P the voltage at point P.

The capacitors of the capacitors 10 and 13 will be chosen so that C ₁₃ >> C ₁₀ , the resistance 14 will be chosen low.

The organ or equipment whose state we want to control activates the closure and the opening of the switch 5.

When the switch 5 is open, the voltage upstream of the diode 16 is zero and the current i _led through the led of the optocoupler 7 is zero, the latter then delivering no output current on the connection S.

When the switch 5 is actuated from its open position to its position closed, then begins two distinct phases depending on the output voltage of the voltage generator 1. Suppose the electrical circuit in steady state.

In a first phase, the voltage across generator 1 goes from - Vg / 2 to + Vg / 2 at time t = 0. The inductance 6 of value L is then subjected to the voltage delivered by the accumulator 3 through the diode 16 and the diode 12 immediately goes to the conducting state, the voltage V _A at the point A becoming equal to the voltage V _P at point P, either by considering the voltage in the second branch 9 and neglecting the voltage across the resistor 14: V _A = V _P ≈ E + Vd.

As the diode 12 is conducting, the charge variation of the capacitor 10 of the first branch 8 is instantly transferred through the diode 12 into the capacitor 13 of the second branch 9 by following the relationship: ΔQ C10 = C 10 * ΔU = C 10 * (V AT (-t 0 <t <0) - (- vg 2 ) - (V AT (0 <t < 0 ) - vg 2 )) with V AT (-t 0 <t <0) = E-Vc-Vd-Vled and V AT (0 <t < 0 ) = E + Vd. From where ΔQ C10 = C 10 * (Vg-Vc-2 * Vd-Vled).

The charge variation of the inductance 6 of the first branch is also immediately transferred through the diode 12 into the capacitor 13 with a slight increase in the voltage across its terminals (because C ₁₃ >> C ₁₀ ) and the charges are then dissipated in the resistance 14.

During this first phase, the current variation in the inductor 6 can be calculated from the relationship U _L = L * di / dt with the voltage across the inductor 6 which is equal to U _L = E-Vc -Vd- (E + Vd + Vled), hence: U The = - (2 * Vd + Vled + Vc).

,l'inductance 6 jouant alors le rôle de générateur de courant. La valeur L de l'inductance étant grande, on a donc Δi_led (t₀)= - Vc+2*Vd+Vled / L*t₀ qui est très faible. La variation de courant au travers de la led de l'optocoupleur 7 durant la première phase est donc très faible.The current in the inductance therefore evolves linearly during the first phase, following the relationship

, inductance 6 then playing the role of current generator. The value L of the inductance being large, we therefore have Δi _led (t ₀ ) = - Vc + 2 * Vd + Vled / L * t ₀ which is very low. The variation in current through the LED of the optocoupler 7 during the first phase is therefore very small.

In a second phase, the voltage across the generator goes from + Vg / 2 to - Vg / 2 for t = t ₀ and the diode 12 goes to the blocked state. The voltage at point A then immediately changes to V _A = E + Vd-Vg and varies to reach the value V _A = E-Vc-Vd-Vled for t = 2 * t0 again corresponding to the start of the first phase. During this phase the current passing through the inductor 6 is blocked by the diode 12 and is therefore transferred entirely in the capacitor 10 which receives the charge: ΔQ C10 = C 10 * (Vg-Vc-2 * Vd-Vled). The capacitor 10 therefore finds the charge it had lost during the first phase.

soit ΔiL(t)= Vg-Vc-2*Vd-Vled L *(t- t 2 2*t o ) At the terminals of the capacitor 10, ΔU (t) = i _led * t / C ₁₀ with i _led is substantially constant because the value L of the inductance 6 is large. It is therefore deduced therefrom that the voltage changes substantially linearly over time.
So we have the voltage at point A which evolves according to the relation: V AT (T) = V t = 2 t0 - V t = t 0 t 0 * t + V t = t 0 we obtain : V AT (t) = ( vg - Vc - Vd - Vled ) - ( E + Vd - vg ) t 0 * T + E + Vd-Vg , Is V AT (T) = vg - Vc - 2 * Vd - Vled t 0 * T + E + Vd-Vg , The voltage across inductance 6 is determined by the relationship U The (t) = (E-Vc-Vd-Vled) -V AT (T), From where U The (t) = (E-Vc-Vd-Vled) - ( vg - Vc - Vd - Vled ) - ( E + Vd - vg ) t 0 * T + E + Vd-Vg Is U The (t) = - ( vg - Vc -2 * Vd - Vled ) t 0 * T + ( Vg-VC- 2 * Vd-Vled ) And

is dI The (T) = vg - Vc -2 * Vd - Vled The * ( t - t 2 2 * t o )

The variation of the current i _L in the inductance 6 during the first and second phases is shown in an exaggerated manner, in order to be better visible, on the graph of FIG. 3.
According to this figure, the current i _L in the inductor 6 without being completely constant only evolves over a reduced range. Its average value can be adjusted, so as to obtain the passage of the minimum current required to ensure the cleaning of the switch 5, by regulating the duty cycle, here taken equal to α = t 0/2 * t 0 = 1/2 and the amplitude of the voltage Vg produced by the generator 1.

The current flowing through the inductor 6 also flows in the optocoupler 7, it thus establishes, when the switch 5 is closed, a current in optocoupler 7, which produces in response an output signal on connection S. La position of the optocoupler 7 in series with the switch 5 is advantageous since the signal it generates as an output is a fairly faithful image of the current flowing inductor 5.

The operation of the invention which has just been described reduces the energy dissipated by Joule effect in two ways.

First, the voltage generator 1 maintains the energy level in the circuit, and only the power it releases for this purpose is consumed by the Joule effect.

Secondly, the intensity of the current i _L injected into the circuit is independent of the voltage E delivered by the accumulator 3. Thus, a variation of the voltage E delivered by the accumulator 3 does not introduce a variation of the current consumed by resistance 14.

FIG. 4 represents an alternative embodiment of the electrical circuit of the Figure 1 in which a clipper 11 is disposed between a point between the switch 5 and the diode 16 and the negative terminal of the accumulator 3. The operation of the circuit remains the same, the clipper 11 providing additional resistance to surges.

In another variant not shown, the galvanically isolated connection 7 will consist of a magnetic coupling produced by a transformer whose primary winding also forms, at least in part, that of the inductor 6, the secondary being, for its part, connected to connection S. The operation of the electrical circuit remains unchanged. The variation of the current i _L in the inductor 6, when the switch 5 is closed, produces at the output a voltage and / or a current at the terminals of the secondary of the transformer 7 which constitute the output signal after rectification by a rectifier not shown .

In another alternative embodiment not shown, the insulation link galvanic 7 may be placed in series with the load resistor 14, the operation of the elementary circuit remaining the same.

The invention is not limited to the variant embodiments which have just been described. In particular, the current generator can provide other waveforms variables such as triangular or sinusoidal centered or not on 0 volts. Indeed, it was chosen in the embodiment described above a variable voltage generator producing a square wave to simplify the equations and facilitate the explanation of the operation of the electrical circuit, however in practice we will choose advantageously a voltage generator producing a triangular signal.

The invention is not limited to a railway application, but relates to the transmission, in any field, of all or nothing information.

Among the advantages of the invention, it will be noted that the presence of the inductance upstream of the optocoupler makes it possible to smooth the current passing through the optocoupler which then has a low ripple which is favorable for a good service life of the optocoupler.

In addition, the inductance at the input of the electrical circuit also allows limit the generation of electromagnetic noise that can be transmitted to others equipment.

The presence of capacitors between the positive terminal and the negative terminal of the accumulator also makes it possible to guarantee, in the event of failure of one of the components active in the electrical circuit, that in no case is there a short circuit across the the accumulator.

Claims (14)

Electrical circuit for transmitting the state of a parameter or equipment, intended to be connected to the terminals of a supply accumulator (3) and comprising: a galvanically isolated connection (7) between said electrical circuit and an output S for the emission of status information, and a switch (5), the open or closed position of which is representative of the state information and which determines the passage of a current in said electrical circuit, the electrical circuit ensuring the transmission of the state information of the switch (5) to the output S, via the galvanically isolated link (7), characterized in that , to regulate the intensity of the current in the switch (5), it comprises means for generating variable voltage (1) cooperating with switching means (12) for selectively supplying elements constituting the electrical circuit in function of the output voltage of said variable voltage generating means (1) and in that it comprises inductive filtering means (6) in series with the switch (5) and capacitive storage means (13) which , in steady state, each forms storage means and means for restoring part of the energy of said electrical circuit, according to the output voltage of the variable voltage generator (1). Electric circuit according to claim 1, characterized in that the inductive filtering means (6) are arranged in the immediate vicinity of the switch (5). Electric circuit according to claim 2, characterized in that a diode (16) is interposed between said switch (5) and said inductive filtering means (6), said diode (16) so as to prevent the flow of current from the switch (5) of the inductive filtering means (6) towards the switch (5). Electric circuit according to any one of the preceding claims, characterized in that the inductive filtering means consist of an inductor (6), the electric circuit comprising in series with the switch (5) and the inductor (6) , first and second branches (8,9) in parallel, and comprising a resistor (14), in parallel with the switch (5) and the inductor (6), connected to a point (P) of the second branch (9), a capacitor (10) being connected in the first branch (8), and in that the switching means of the connections comprise a diode (12) connected in the second branch (9) between on the one hand, l '' one of the junctions of the first and second branch (8,9), and on the other hand, the point (P) of connection of the resistor (14) on the second branch (9), the second branch (9) also comprising a capacitor (13) connected between on the one hand the other of these junctions of the first and second branches (8, 9) and on the other hand, the point (P) of connection of the resistor (14) on the second branch (9). Electric circuit according to claim 4, characterized in that the galvanically isolated connection (7) is connected in series with the inductive filtering means (6). Electric circuit according to claim 4, characterized in that the galvanically isolated connection (7) is connected in series with the resistor (14). Electrical circuit according to any one of the preceding claims, characterized in that the signal produced by the voltage generator means is a rectangular, triangular or sinusoidal signal centered or not on 0 volts. Electric circuit according to any one of Claims 1 to 7, characterized in that the variable voltage generating means are connected in the first branch (8). Electrical circuit according to any one of the preceding claims, characterized in that the galvanically isolated connection (7) consists of an opto-coupler. Electrical circuit according to any one of the preceding claims, characterized in that the galvanically isolated connection (7) consists of a transformer. Electric circuit according to claim 10, characterized in that the galvanically isolated connection (7) consists of a transformer connected in series with the switch (5) and the primary of which also forms at least part of the inductive storage means. Electric circuit according to any one of the preceding claims, characterized in that , the input of the switch (5) being connected to a terminal of the accumulator (3), a clipper (11) is arranged between the output of said switch (5) and the other terminal of the accumulator (3). Electrical system (1) for transmitting a plurality of state information, characterized in that it comprises an accumulator (3) and a plurality of electrical circuits according to any one of Claims 1 to 12, each intended for transmitting status information and connected in parallel to the terminals of said accumulator (3). Electrical system (1) according to claim 13, characterized in that it is on board a railway convoy, each switch (5) being associated with a member or an equipment of said railway convoy, to control the state or the position thereof.

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