EP1209709B1 - 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 the routing of all-or-nothing information, particularly for an application in the railway field.

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

One solution currently used is to connect to the two terminals of a battery a closed loop electrical circuit, which comprises in series at least one switch linked to the state of the body to be monitored, a resistor, and a galvanically isolated connection connected to the receiving device of the information contained in the signal, for example the electronic controller control circuit or the control and signaling board.

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, whose intensity is limited by the resistance, circulates in the circuit. When it is open, no current flows. The presence or absence of this current is transformed by the galvanically isolated connection into an all or nothing information communicated to the electronic circuit. DE 44 13 467 C1 discloses an electric circuit according to the preamble of claim 1.

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

As the switches tend to oxidize, a minimum current intensity, of the order of a few tens of milliamperes, must pass through each of these switches to clean them. This current is consumed at a loss in the resistance. In addition, the power dissipated in the Joule effect produces heat, which must be removed. A known solution is to use fans, however, at present, it is avoided, or even prohibited, to use such fans as a cooling mode of the electronic circuits embedded in the trains for reasons of reliability, a fan with mechanical components that can become jammed, seized and, in general, cause a failure.

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

Moreover, the battery generally supplying several circuits, and other equipment, the voltage it delivers varies over time with the level of the 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 the cleaning of the switches, it is necessary to consent to consume a large amount of current and therefore power, during certain periods during the operation of the circuit. The additional heat production that 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 purpose of the invention is therefore to provide the routing of all-or-nothing information 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 equipment, intended to be connected to the terminals of a supply battery and comprising:

• a galvanically isolated link between said electrical circuit and an output for transmitting state information, and
• a switch whose open or closed position 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 status information of the switch to the output, via the galvanically isolated connection,

characterized in that, to regulate the intensity of the current in the switch, it comprises variable voltage generating means cooperating with switching means for selectively supplying constituent elements of the electric circuit as a function of the output voltage of the generating means 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 of restitution of a part of the energy of the electric 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 electric circuit:

• the inductive filtering means are arranged in the immediate vicinity of the switch;
• a diode is interposed between the switch and the inductive filtering means, the diode being biased so as to prevent the flow of current from the self-filtering means towards the switch;
• the inductive filtering means consist of an inductor, the electrical circuit comprising in series with the switch and the inductor, first and second branches in parallel, and having 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 branches, 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 on the second branch;
• the galvanically isolated connection is connected in series with the inductive filtering means;
• the galvanically isolated connection 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 centered 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 whose primary element also forms at least a part of the inductive storage means;
• the input of the switch is connected to one terminal of the accumulator and a limiter is arranged between the output of the switch and the other terminal of the accumulator.

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

According to another characteristic of this electrical system, it is embedded in a railroad train, each switch being associated with a body or equipment of the railway train, to control the 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 apparaître 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 with reference to the appended drawings, in which:

• FIG. 1 represents an electrical circuit for transmitting 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,
• FIG. 3 represents a graph illustrating the theoretical value of the current as a function of time in the branch of the circuit comprising the switch, the representation along the ordinate axis being enlarged so as to accentuate 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 understanding the invention have been shown. The same elements bear the same references from one figure to another.

FIG. 1 represents a particular embodiment of a transmission circuit capable of transmitting an all or nothing information representative of the state of an organ or equipment to be tested, in particular a railway vehicle equipment. FIG. 1 isolates an elementary circuit belonging to a more complete electrical system, not shown, comprising a plurality of similar elementary circuits connected in parallel across an accumulator and capable of transmitting a plurality of all or nothing information to an electronic control circuit for controllers.

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

The electronic circuit 2 also includes output ports 4 for 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 embedded in a train. It goes without saying that the electronic control circuit 2 of PLCs can be replaced by a control and signaling board or by any device capable of receiving and processing an all or nothing information.

Generally, the accumulator 3 is the only source of DC voltage for the entire train. Also, the various on-board equipment that requires a DC power supply are powered by this single battery 3. The voltage 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.

Accumulators 3 generally currently used in trains, have nominal voltages of 24 volts, 36 volts, 48 volts, 96 volts and 110 volts.

According to FIG. 1, the transmission electrical circuit comprises a loop B fed 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 realized by means of an optocoupler, and two branches 8 and 9 in parallel originating at a point A disposed at the output of the galvanically isolated connection 7. The diode 16 is polarized so as to prohibit the discharge of the inductance 6 elsewhere than through the optocoupler 7.

For the sake of convenience, the following convention is adopted in the following description: the flow direction of a current in the loop B of the positive terminal to the negative terminal of the battery 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 wave signal of half-period t ₀ and peak to peak amplitude V g symmetrical as shown in Figure 2. The value of the amplitude Vg of voltage will be chosen lower than the voltage E across the accumulator 3 and will, for example, be of the order of 15 V.

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 anywhere else than by 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 rest of the 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 the input contact 5, with Vc <E,
• V _At the voltage at point A and V _P the voltage at point P.

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

The organ or the equipment whose state is to be controlled actuates the closing and 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 closed position, then starts two distinct phases as a function of the output voltage of the voltage generator 1. The electrical circuit is assumed in steady state.

à + $+\frac{{\mathit{Vg}}_{\mathit{\hspace{1em}}}}{2}$

au temps t=0. L'inductance 6 de valeur L est alors soumise à la tension délivrée par l'accumulateur 3 au travers de la diode 16 et la diode 12 passe immédiatement à l'état conducteur, la tension V_A au point A devenant égale à la tension V_P au point P, soit en considérant la tension dans la deuxième branche 9 et en négligeant la tension aux bornes de la résistance 14 : V_A=V_P ≈ E+Vd.In a first phase, the voltage across the generator 1 goes from - $-\frac{{\mathit{<figure-callout\; id="2"\; label="vg"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">vg</figure-callout>}}_{\mathrm{}}}{2}$

to + $+\frac{{\mathit{<figure-callout\; id="2"\; label="vg"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">vg</figure-callout>}}_{\mathit{}}}{2}$

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 switches to the conductive state, the voltage V _A at the point A becoming equal to the voltage V _P at the point P, either considering the voltage in the second branch 9 and neglecting the voltage across the resistor 14: V _A = V _P ≈ E + Vd.

avec $${\mathrm{V}}_{\mathrm{A}}\left(\mathrm{-}{\mathrm{t}}_{\mathrm{0}}\mathrm{<}\mathrm{t}\mathrm{<}\mathrm{0}\right)\mathrm{=}\mathrm{E}\mathrm{-}\mathrm{Vc}\mathrm{-}\mathrm{Vd}\mathrm{-}\mathrm{Vled\hspace{1em}et\hspace{1em}}{\mathrm{V}}_{\mathrm{A}}\left(\mathrm{0}\mathrm{<}\mathrm{t}\mathrm{<}{\mathrm{t}}_{\mathrm{0}}\right)\mathrm{=}\mathrm{E}\mathrm{+}\mathrm{Vd}\mathrm{.}$$

D'où $$\mathrm{\Delta }{\mathrm{Q}}_{\mathrm{C}\mathrm{10}}\mathrm{=}{\mathrm{C}}_{\mathrm{10}}\mathrm{*}\left(\mathrm{Vg}\mathrm{-}\mathrm{Vc}\mathrm{-}\mathrm{2}\mathrm{*}\mathrm{Vd}\mathrm{-}\mathrm{Vled}\right)\mathrm{.}$$

Since the diode 12 is conducting, the charge variation of the capacitor 10 of the first branch 8 is instantaneously transferred through the diode 12 in the capacitor 13 of the second branch 9 by following the relation: $$\mathrm{\Delta }{\mathrm{Q}}_{\mathrm{VS}\mathrm{10}}\mathrm{=}{\mathrm{<figure-callout\; id="10"\; label="VS"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{\mathrm{10}}\mathrm{*}\mathrm{\Delta U}\mathrm{=}{\mathrm{<figure-callout\; id="10"\; label="VS"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{\mathrm{10}}\mathrm{*}\left({\mathrm{V}}_{\mathrm{AT}}\left(\mathrm{-}{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{0}}\mathrm{<}\mathrm{t}\mathrm{<}\mathrm{0}\right)\mathrm{-}\left(\mathrm{-}\frac{{\mathit{vg}}_{\mathrm{}}}{\mathrm{2}}\right)\mathrm{-}\left({\mathrm{V}}_{\mathrm{AT}}\left(\mathrm{0}\mathrm{<}\mathrm{t}\mathrm{<}{\mathrm{t}}_{\mathrm{0}}\right)\mathrm{-}\frac{{\mathit{<figure-callout\; id="2"\; label="vg"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">vg</figure-callout>}}_{\mathrm{}}}{\mathrm{2}}\right)\right)$$

with $${\mathrm{V}}_{\mathrm{AT}}\left(\mathrm{-}{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{0}}\mathrm{<}\mathrm{t}\mathrm{<}\mathrm{0}\right)\mathrm{=}\mathrm{E}\mathrm{-}\mathrm{Vc}\mathrm{-}\mathrm{Vd}\mathrm{-}\mathrm{Vled\; and}<figure-callout\; id="0"\; label="\; V\; AT"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\; </figure-callout>{\mathrm{V}}_{\mathrm{AT}}{\mathrm{}}_{}\left(\mathrm{0}\mathrm{<}\mathrm{t}\mathrm{<}{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{0}}\right)\mathrm{=}\mathrm{E}\mathrm{+}\mathrm{Vd}\mathrm{.}$$

From where $$\mathrm{\Delta }{\mathrm{Q}}_{\mathrm{VS}\mathrm{10}}\mathrm{=}{\mathrm{<figure-callout\; id="10"\; label="VS"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{\mathrm{10}}\mathrm{*}\left(\mathrm{vg}\mathrm{-}\mathrm{Vc}\mathrm{-}\mathrm{2}\mathrm{*}\mathrm{Vd}\mathrm{-}\mathrm{Vled}\right)\mathrm{.}$$

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

During this first phase, the current variation in the inductance 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), where: $${\mathrm{U}}_{\mathrm{The}}\mathrm{=}\mathrm{-}\left(\mathrm{2}\mathrm{*}\mathrm{Vd}\mathrm{+}\mathrm{Vled}\mathrm{+}\mathrm{Vc}\right)\mathrm{.}$$

,l'inductance 6 jouant alors le rôle de générateur de courant. La valeur L de l'inductance étant grande, on a donc ${\mathrm{\Delta i}}_{\mathrm{led}}\left({\mathrm{t}}_0\right)=-\frac{\mathit{Vc}\mathit{+}\mathrm{2}\mathrm{*}\mathit{Vd}\mathit{+}\mathit{Vled}}{\mathit{L}}$

*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 thus evolves linearly during the first phase, following the relation ${\mathit{dI}}_{\mathrm{led}}\left(\mathbf{t}\right)\mathit{=}{\displaystyle {\mathit{\int }}_{\mathit{0}}^{\mathit{t}}}\mathit{-}\frac{\mathit{Vc}\mathit{+}\mathit{2}\mathit{*}\mathit{Vd}\mathit{+}\mathit{Vled}}{\mathit{The}}\mathit{*}\mathit{dt}\mathit{,}$

the inductor 6 then acting as a current generator. Since the value L of the inductance is large, we have ${\mathrm{dI}}_{\mathrm{led}}\left({\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)=-\frac{\mathit{Vc}\mathit{+}\mathrm{2}\mathrm{*}\mathit{Vd}\mathit{+}\mathit{Vled}}{\mathit{The}}$

* t ₀ which is very weak. The current variation through the led of the optocoupler 7 during the first phase is very low.

à $-\frac{{\mathit{Vg}}_{\mathrm{\hspace{1em}}}}{2}$

pour t = t₀ et la diode 12 passe à l'état bloqué. La tension au point A passe alors immédiatement à V_A= E+Vd-Vg et varie pour atteindre la valeur V_A= E-Vc-Vd-Vled pour t=2*t0 correspondant de nouveau au début de la première phase. Durant cette phase le courant traversant l'inductance 6 est bloqué par la diode 12 et est donc transféré intégralement dans le condensateur 10 qui reçoit la charge : $${\mathrm{\Delta Q}}_{\mathrm{C}\mathrm{10}}\mathrm{=}{\mathrm{C}}_{\mathrm{10}}\mathrm{*}\left(\mathrm{Vg}\mathrm{-}\mathrm{Vc}-2*\mathrm{Vd}\mathrm{-}\mathrm{Vled}\right)\mathrm{.}$$

Le condensateur 10 retrouve donc la charge qu'il avait perdu durant la première phase.In a second phase, the voltage across the generator changes from $+\frac{\mathit{<figure-callout\; id="2"\; label="vg"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">vg</figure-callout>}}{2}$

at $-\frac{{\mathit{<figure-callout\; id="2"\; label="vg"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">vg</figure-callout>}}_{\mathrm{}}}{2}$

for t = t ₀ and diode 12 goes to the off state. The voltage at point A then passes immediately to V _A = E + Vd-Vg and varies to reach the value V _A = E-Vc-Vd-Vled for t = 2 * t0 corresponding again at the beginning of the first phase. During this phase, the current flowing through the inductor 6 is blocked by the diode 12 and is therefore transferred integrally into the capacitor 10 which receives the charge: $${\mathrm{\Delta Q}}_{\mathrm{VS}\mathrm{10}}\mathrm{=}{\mathrm{<figure-callout\; id="10"\; label="VS"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{\mathrm{10}}\mathrm{*}\left(\mathrm{vg}\mathrm{-}\mathrm{Vc}-2*\mathrm{Vd}\mathrm{-}\mathrm{Vled}\right)\mathrm{.}$$

The capacitor 10 thus regains the charge that it had lost during the first phase.

avec i_led est sensiblement constant du fait que la valeur L de l'inductance 6 est grande. On en déduit donc que la tension évolue sensiblement linéairement dans le temps.
On a donc la tension au point A qui évolue suivant la relation: $${\mathrm{V}}_{\mathrm{A}}\left(\mathrm{t}\right)=\frac{V_{\mathit{t}=2\mathit{t}0}-{V_{\mathit{t}}}_{=\mathit{t}0}}{t_0}*t{+\mathit{V}}_{\mathit{t}\mathit{=}\mathit{t}0},$$

on obtient : $${\mathrm{V}}_{\mathrm{A}}\left(\mathrm{t}\right)=\frac{\mathit{(}\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{Vd}\mathit{-}\mathit{Vled})-\left(E\mathit{+}\mathit{Vd}\mathit{-}\mathit{Vg}\right)}{t_0}*t\mathit{+}\mathit{E}\mathit{+}\mathit{Vd}\mathit{-}\mathit{Vg},$$

Soit $${\mathrm{V}}_{\mathrm{A}}\left(\mathrm{t}\right)=\frac{\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}2*\mathit{Vd}\mathit{-}\mathit{Vled}}{t_0}*t\mathit{+}\mathit{E}\mathit{+}\mathit{Vd}\mathit{-}\mathit{Vg},$$

La tension aux bornes de l'inductance 6 est déterminée par la relation $${\mathrm{U}}_{\mathrm{L}}\left(\mathrm{t}\right)\mathrm{=}\left(\mathrm{E}\mathrm{-}\mathrm{Vc}\mathrm{-}\mathrm{Vd}\mathrm{-}\mathrm{Vled}\right)\mathrm{-}{\mathrm{V}}_{\mathrm{A}}\left(\mathrm{t}\right)\mathrm{,}$$

D'où $${\mathrm{U}}_{\mathrm{L}}\left(\mathrm{t}\right)=\left(\mathrm{E}-\mathrm{Vc}-\mathrm{Vd}-\mathrm{Vled}\right)-\frac{\left(\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{Vd}\mathit{-}\mathit{Vled}\right)}{t_0}*t\mathit{+}\mathit{E}\mathit{+}\mathit{Vd}\mathit{-}\mathit{Vg}$$

Soit $${\mathrm{U}}_{\mathrm{L}}\left(\mathrm{t}\right)=-\frac{\left(\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)}{t_0}*t+\left(\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}\mathrm{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)$$

Et $${\mathrm{\Delta i}}_L\left(t\right)=\frac{1}{L}{\int }_0^t-\left(\frac{\left(\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)}{t0}*\mathrm{\tau }+\left(\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}\mathrm{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)\right)*\mathrm{d\tau }$$

soit $${\mathrm{\Delta i}}_{\mathrm{L}}\left(\mathrm{t}\right)=\frac{\mathit{Vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}}{L}*\left(t-\frac{t^2}{2*t_0}\right)$$

At the terminals of the capacitor 10, $\mathrm{\Delta U}\left(t\right)=\frac{i_{\mathit{led}}*t}{{\mathrm{VS}}_{10}}$

with i _LED is substantially constant because the value L of the inductor 6 is large. It follows that the voltage evolves substantially linearly over time.
So we have the voltage at point A which evolves according to the relation: $${\mathrm{V}}_{\mathrm{AT}}\left(\mathrm{t}\right)=\frac{V_{\mathit{t}=2\mathit{t}0}-{V_{\mathit{t}}}_{=\mathit{t}0}}{t_0}*t{+\mathit{V}}_{\mathit{t}\mathit{=}\mathit{t}0},$$

we obtain : $${\mathrm{V}}_{\mathrm{AT}}\left(\mathrm{t}\right)=\frac{\mathit{(}\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{Vd}\mathit{-}\mathit{Vled})-\left(E\mathit{+}\mathit{Vd}\mathit{-}\mathit{vg}\right)}{t_0}*t\mathit{+}\mathit{E}\mathit{+}\mathit{Vd}\mathit{-}\mathit{vg},$$

Is $${\mathrm{V}}_{\mathrm{AT}}\left(\mathrm{t}\right)=\frac{\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}2*\mathit{Vd}\mathit{-}\mathit{Vled}}{t_0}*t\mathit{+}\mathit{E}\mathit{+}\mathit{Vd}\mathit{-}\mathit{vg},$$

The voltage across the inductance 6 is determined by the relation $${\mathrm{U}}_{\mathrm{The}}\left(\mathrm{t}\right)\mathrm{=}\left(\mathrm{E}\mathrm{-}\mathrm{Vc}\mathrm{-}\mathrm{Vd}\mathrm{-}\mathrm{Vled}\right)\mathrm{-}{\mathrm{V}}_{\mathrm{AT}}\left(\mathrm{t}\right)\mathrm{,}$$

From where $${\mathrm{U}}_{\mathrm{The}}\left(\mathrm{t}\right)=\left(\mathrm{E}-\mathrm{Vc}-\mathrm{Vd}-\mathrm{Vled}\right)-\frac{\left(\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{Vd}\mathit{-}\mathit{Vled}\right)}{t_0}*t\mathit{+}\mathit{E}\mathit{+}\mathit{Vd}\mathit{-}\mathit{vg}$$

Is $${\mathrm{U}}_{\mathrm{The}}\left(\mathrm{t}\right)=-\frac{\left(\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)}{t_0}*t+\left(\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}\mathrm{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)$$

And $${\mathrm{dI}}_{\mathrm{The}}\left(t\right)=\frac{1}{\mathrm{The}}{\int }_0^t-\left(\frac{\left(\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)}{t0}*\mathrm{\tau }+\left(\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}\mathrm{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}\right)\right)*\mathrm{d\tau }$$

is $${\mathrm{dI}}_{\mathrm{The}}\left(\mathrm{t}\right)=\frac{\mathit{vg}\mathit{-}\mathit{Vc}\mathit{-}\mathit{2}\mathit{*}\mathit{Vd}\mathit{-}\mathit{Vled}}{\mathrm{The}}*\left(t-\frac{t^2}{2*t_0}\right)$$

et l'amplitude de la tension Vg produite par le générateur 1.The variation of the current i _L in the inductance 6 during the first and second phases is represented in an exaggerated manner, in order to be better visible, on the graph of FIG.
According to this figure, the current i _L in the inductor 6 without being quite constant evolves only on a reduced range. Its average value can be adjusted, so as to obtain the passage of the minimum current required to ensure cleaning. the switch 5, regulating the duty cycle, here taken equal to $\mathrm{\alpha }=\frac{{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_0}{2<figure-callout\; id="0"\; label="*\; t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">*\; </figure-callout>t_{}{}_0}=\frac{1}{2}$

and the amplitude of the voltage Vg produced by the generator 1.

As the current flowing through the inductor 6 also flows in the optocoupler 7, a current in the optocoupler 7 is set up when the switch 5 is closed, which generates in response an output signal on the The position of the optocoupler 7 in series with the switch 5 is advantageous since the signal which it generates at the output is a substantially faithful image of the current which passes through the inductor 5.

The operation of the invention which has just been described reduces the energy dissipated by the 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 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 the resistance 14.

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

In another variant not shown, the galvanically isolated connection 7 will consist of a magnetic coupling made 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 a voltage output and / or a current across the secondary of the transformer 7 which constitute the output signal after rectification by a rectifier not shown .

In another embodiment not shown, the galvanically isolated connection 7 may be placed in series with the load resistor 14, the operation of the elementary circuit remains the same.

The invention is not limited to the embodiments that have just been described. In particular, the current generator may provide other variable waveforms such as triangular or sinusoidal, centered or not on 0 volts. Indeed, it has been chosen in the embodiment previously described a variable voltage generator producing a square signal to simplify the equations and facilitate the explanation of the operation of the electrical circuit, however in practice one will advantageously choose 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 flowing through the optocoupler, which then has a small undulation which is favorable to a good service life of the optocoupler.

In addition, the inductance at the input of the electrical circuit also makes it possible to limit the generation of electromagnetic noises that can be transmitted to other 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 active components of the electrical circuit, that in no case is there a short circuit at the terminals of the accumulator.

Claims (14)

1. Electrical circuit for transmitting the state of a parameter or of an item of equipment, intended to be connected to the terminals of a power supply accumulator (3) and including:

   - a galvanic isolation link (7) between the said electrical circuit and an output S for the transmission of state 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 the said electrical circuit, the electrical circuit providing the transmission of the state information of the switch (5) to the output S, via the galvanic isolation link (7),

   characterised in that, in order to regulate the strength of the current in the switch (5), it includes variable voltage generating means (1) co-operating with switching means (12) to selectively power components forming the electrical circuit according to the output voltage of the said variable voltage generating means (1) and in that it includes inductive filtering means (6) in series with the switch (5) and capacitive storage means (13) which, in the steady state, each form means of storage and of restitution of a part of the energy of the said electrical circuit, according to the output voltage of the variable voltage generator (1).
2. Electrical circuit according to Claim 1, characterised in that the inductive filtering means (6) are arranged in immediate proximity to the switch (5).
3. Electrical circuit according to Claim 2, characterised in that a diode (16) is placed between the said switch (5) and the said inductive filtering means (6), the said diode (16) being polarised so as to prevent the current
   flowing from the inductive filtering means (6) towards the switch (5).
4. Electrical circuit according to any one of the preceding claims, characterised in that the inductive filtering means are formed of an inductance (6), the electrical circuit including in series with the switch (5) and the inductance (6), first and second branches (8, 9) in parallel, and including a resistance (14), in parallel with the switch (5) and the inductance (6), connected at a point (P) of the second branch (9), a capacitance (10) being connected in the first branch (8), and in that the switching means for the connections include a diode (12) connected in the second branch (9) between one of the junctions of the first and second branches (8, 9) and the point (P) of connection of the resistance (14) on the second branch (9), the second branch (9) also including a capacitance (13) connected between the other of these junctions of the first and second branches (8, 9) and the point (P) of connection of the resistance (14) on the second branch (9).
5. Electrical circuit according to Claim 4, characterised in that the galvanic isolation link (7) is connected in series with the inductive filtering means (6).
6. Electrical circuit according to Claim 4, characterised in that the galvanic isolation link (7) is connected in series with the resistance (14).
7. Electrical circuit according to any one of the preceding claims, characterised in that the signal produced by the voltage generating means is a rectangular, triangular or sinusoidal signal centred or not on 0 V.
8. Electrical circuit according to any one of Claims 1 to 7, characterised in that the variable voltage generating means are connected in the first branch (8).
9. Electrical circuit according to any one of the preceding claims, characterised in that the galvanic isolation link (7) is formed of an optocoupler.
10. Electrical circuit according to any one of the preceding claims, characterised in that the galvanic isolation link (7) is formed of a transformer.
11. Electrical circuit according to Claim 10, characterised in that the galvanic isolation link (7) is formed of a transformer connected in series with the switch (5) and the primary of which also forms at least a part of the inductive storage means.
12. Electrical circuit according to any one of the preceding claims, characterised in that, the input of the switch (5) being connected to a terminal of the accumulator (3), a limiter (11) is arranged between the output of the said switch (5) and the other terminal of the accumulator (3).
13. Electrical system (1) intended to transmit a plurality of state information items, characterised in that it includes an accumulator (3) and a plurality of electrical circuits according to any one of Claims 1 to 12, each intended to transmit an item of state information and connected in parallel to the terminals of the said accumulator (3).
14. Electrical system (1) according to Claim 13, characterised in that it is installed in a railway train, each switch (5) being associated with a part or with equipment of the said railway train, in order to monitor its state or position.

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