FR3039335A1 - METHOD FOR PROTECTING AGAINST OVERHEATING AND / OR OVERCURRENTS OF AN ELECTRICAL CONNECTOR - Google Patents

Abstract

Method for protecting against overheating and / or overcurrent of an electrical connector (POC, EM) comprising at least one contact point (PC), characterized in that it consists of: (i) measuring the ambient temperature (Tamb) near the connector (POC, EM) and the temperature (Tm) near the point of contact (PC) of the connector (POC, EM); (ii) measuring the intensity (i) of the current flowing in the contact point (PC); (iii) estimating the contact point contact resistance (CP) from the measurement of the ambient temperature (Tamb), the temperature (Tm) near the contact point (PC) of the connector ( POC, EM) and the intensity (i) of the current flowing in the contact point (PC); (iv) to estimate the temperature of the point of contact (Test) from an electrothermal model of the chain of components including the connector (POC, EM) and its environment, model which is recaled by the value of the contact resistance estimated (Rpc); and from the measurements of temperatures (Tamb and Tm) and current (i) and if the variation of the contact resistance (Rpc) is greater than an estimated nominal reference value, to trigger an alarm.

Description

BACKGROUND OF THE INVENTION The invention relates to the field of electrical connection, and more specifically to the connection devices that may be part of electric connection beams.

The term "connecting device" herein means a device comprising at least a first connection means, of the male type, designated by "tongue" *, or female, designated "clip", and which is electrically conductive and suitable for being detachably secured to a second connection means of female or male type and electrically conductive, and an electrical strand (wire, cable or strand) having a stripped portion closely joined to the first connection means by any known means (crimping, welding, gluing or screwing).

In the following description, we will consider a plurality of clips able to cooperate respectively with the same plurality of tabs.

The clips are supported by a clip holder and the tabs by a base.

The term "connector" will denote the assembly formed by the clip holder and the base.

Furthermore, here "electrical harness" means a group of at least two connection devices of the aforementioned type.

Nowadays, the use of numerous electrical and electronic devices and components (computers, sensors, actuators, resistors, etc.) in automobiles makes the consumption of electrical energy ever greater. The electric currents are distributed in the vehicle by electronic boxes and their beams. These currents are routed to the end consumers (called loads) via electrical conductors (electrical wires, busbars, ribbon cables, etc.) and connectors ensuring the continuity of the currents between the loads and the power supply.

A connector is the seat of electrical contact points. A point of contact is between a tongue and a clip and constitutes a zone of fetishing. current lines showing an additional resistance called constriction. the constriction resistance, also known as the contact resistance, results in variations of the heat energy dissipated by the Joule effect at the point of contact. The occurrence of overcurrents and / or the increase of the contact resistance, can therefore produce significant heating in the connector and cause the ignition thereof or electrical son attached thereto. that connectors are among the most critical components to monitor in a motor vehicle.

The monitoring of the connectors is therefore essential to ensure their proper functioning and the safety of their environment.

This observation is even more true on electric / hybrid vehicles where strong electrical powers prevail, in particular. . . There are many devices for detecting overcurrents and / or critical heating and for acting when they occur. We can mention thermal fuses, biiames, alloy devices to:. . . memory of formed, .. so-called "smart" transistors, etc.

There are also several types of modeling and several methods of measuring a contact resistance. A contact resistance is a function of the nature of the contact point surfai of which different models are found in the literature. For example, we can cite statistical models (Greenwood & Williamson, 1966), fractal modeling (Singer & Kshonze, 1991) or multi-scale models (Wilson, Angadi, & Jackson, 2010).

With regard to the methods of measurement of the contact resistance, one can find methods of electrical measurement (Tristani, 2000), thermal (Grandvuiilemin, 2009) or methods of measurement of the real contact surface (Woo & Thomas , 1980).

Unfortunately, the aforementioned devices and methods are poorly adapted to optimally monitor and protect the connectors. Indeed, they only activate depending on the temperature of the point where they are implanted or the current flowing through them. However, it is not possible to implant these devices directly on the points of contact, that is to say inside the connectors. It is also possible to use an integrated control logic such as "smart" transistors (Smart Power ": Device"), which have their own: "p" diagnostic functions, "". Measurement / de-current / and / or temperature, and also have a logic of protection against overheating. ''. '''''' · · · · · · · · · And the Over-currents, They also offer '·' the 'advantage' of being rebootable: ':'; of the total cutoff of the current: (in the case of a short circuit, for example). However, even though these transistors may indirectly protect electrical / electronic circuits, their priority is to first self-protect against the current electrical or electronic circuits. op strong: './'temperature.

Thus, all the devices mentioned above, for example, may be subject to strong heating up: from the source of the source of energy. For example, while the monitored point of contact is not overheated. On the other hand, warming of a contact point can occur because of the increase of its contact resistance and without the current flowing in it has not exceeded. :; /: p: p: p; p ;; pp:

They can potentially fire too late or not at all if they are too far from the point of contact.

Thus, in synthesis, the existing devices are not fully effective because: they depend on a temperature that is not celte the point of contact; they do not discriminate if heating is due to an increase in current, a variation of the contact resistance or another component overheating in the vicinity.

Finally, the rebooting of certain devices is not possible, which sometimes involves manual replacement and tedious components: used.

As regards the different methods of modeling or measurement of contact resistances, these are difficult and / or expensive to implement on a large scale and too often unworkable in real time.

The document FR2990807 entitled "Electronic device for protecting an electrical conductor and method of controlling such a device describes a method for protecting an electric wire against overcurrents and critical heating from a measurement of the current passing through the electrical circuit. The protection is then achieved through the use of a temperature estimator, an algorithm and a controlled MOSFET transistor which limits or prevents the flow of current in case of failure. .

Document FR2968475 entitled "Protection of an electrical socket against temperature" proposes a device for measuring an electrical resistance representative of the temperature in a socket (in particular the plugging of a charging cable for an electric or hybrid vehicle) using a bimetallic (alternatively a thermistor) and resistors. The value of the measured electrical resistance is then transmitted to a protection device, capable of detecting the state of overheating and capable of limiting or cutting off the current in the socket (this protection device is not itself. . ':'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''.

The present invention aims to further protect a connector against overcurrent and critical heating.

It proposes for this purpose a method of protection against overheating and / or overcurrent of an electrical connector having at least one contact point, characterized in that it consists of: (i) measuring the ambient temperature in the vicinity the connector and the temperature near the contact point of the connector; (ii) measuring the intensity of the current flowing in the point of contact; (iii) estimating the contact point resistance from the ambient temperature measurement, the temperature near the contact point of the connector and the intensity of the current flowing in the contact point; (iv) estimating the contact point temperature from an electrothermal model of the component chain including the connector and its environment, which model is recalibrated by the value of the estimated contact resistance; and (v) from the temperature and current measurements and if the variational contact resistance is greater than: a nominal value of estimated value, to trigger an alarm.

According to one characteristic, the method .is, in addition, to exploit ... .the same information of ambient temperature and proximity of the point of contact, of current, to limit and regulate.the current flowing in the point If the temperature of the estimated contact point is greater than a determined limit temperature, the contact temperature is determined by the contact temperature. · 8υΐΓβ characteristic.il consists, to limit and regulate the current flowing in the contact point, chopping said current in a fixed and variable duty cycle until the temperature is below a predetermined threshold temperature.

According to another characteristic, the duty cycle is equal to 1 when the estimated temperature remains lower than or equal to the limit temperature; the electric charge present on the point of contact imposing the electric current.

The second subject of the present invention is a device for implementing the method cited above, characterized in that it comprises: a temperature sensor able to measure the ambient temperature close to the connected connector; measuring means able to measure the temperature near the point of contact; a diagnostic and estimation module, able to monitor the variations of the contact resistance of the contact point, and to estimate the value of the contact resistance of the contact point; an electronic switch, of the MOSFET type, controlled by mode pulse width modulation according to a predetermined period and a variable duty cycle, and able to measure the current flowing in the contact point to which it is connected; and a control module capable of determining and transmitting to the switch, at regular intervals, the value of the duty cycle calculated from the data of the temperature and current sensors.

According to one characteristic, the control module comprises a temperature estimator which transmits the estimated temperature of the contact point to a regulator; the estimator is based on the electrothermal model which is recaled by the value of the contact resistance estimated and transmitted by the diagnostic and estimation module.

According to another caraététistry, the measuring means comprise an auxiliary wire strand of fixed length crimped by double crimping with the functional wire through which the electric current flows and whose common ends are connected near the point of contact; said auxiliary strand, initially provided as a radiator wire, being provided with a thermistor-type component, placed in series between the contact point and a reference potential, able to deduce its own temperature from the value of its electrical resistance. According to another characteristic, the measuring means use a large voltage divider bridge a resistance of determined value and dimensioned to minimize the Joule effect in the radiator wire, placed in series between the thermistor. CTN or CTP and the reference potential, and an RFID chip disposed across the resistor; said RFID chip being capable of transmitting the voltage read across the resistor to a receiver. .

According to one variant, the divider bridge is replaced by a bridge of

Wheatstone :: ..:;: v.: ..

According to a variant, the measuring means comprise an auxiliary wire strand of predetermined length crimped by double crimping with the functional fit through which the electric current flows and whose common ends are connected close to the point of contact; said means being provided with a thermocouple whose pair of measuring wires are either welded to a stripped portion of the radiator wire near the double crimping or directly bonded to the double crimping.

According to one variant, the measuring means comprise a component of the NTC or CTP thermistor type, soldered or brazed on a tab corresponding to a point of contact, close to the point of contact, and able to deduce its own temperature from the value its electrical resistance; the component being welded or brazed on the tongue when the latter is in the open air.

According to one variant, the measurement means implement a voltage divider bridge comprising a determined value of resistance whose first terminal is coupled to a tab to be monitored and whose second terminal is coupled to the CTN or CTP thermistor connected in series between the thermistor and another determined reference potential tab, common to all measurements, and an RFID chip disposed across the resistor; said RFID chip being able to transmit the voltage read across the resistor to a receiver.

According to one characteristic, there are as many reference tabs of potential as tabs to monitor; a reference tongue being adjacent to a tab to be monitored. According to another feature, the measuring means comprise a thermocouple whose measurement wires are soldered or brazed to a tab corresponding to a point of contact, near the point of contact. .. contact. The advantage of the present invention is to improve the protection of the. connector even when there is a change in contact resistance. The invention is well adapted, although not limited to vehicles, possibly of automotive type.

This invention may also be useful for any electrical system having connectors. It makes it possible to prevent any aggravated short circuit (hence the risk of ignition), especially for applications with high electrical powers similar to those found in electric / hybrid vehicles.

This invention can thus find an economic interest in a multitude of fields of application, for example for other means of transport. Other features and advantages of the invention will appear on examining the detailed description below, and the accompanying drawings, in which: FIG. 1 illustrates the method according to the invention and its means of implementation presented under the shape of a block-diagram; FIG. 2 shows the side view of an in situ connector illustrating the concept of a first embodiment of the measuring means 11111 of a device for the purpose of the process of the invention; FIG. 3 illustrates schematically a view of the first embodiment of the temperature measurement means implemented by FIG. FIG. 4 schematically illustrates the principle of measurement implemented. The first embodiment of the measuring means is described in FIG. FIG. 5 is a diagrammatic illustration of the use of RFID devices by the first method of producing the measurement means; FIG. 6 depicts the side view of a single unit in FIG. situ illustrating the conco The second embodiment of the present invention relates to a method of carrying out a method for measuring the temperature of a device for carrying out the process according to the invention. Figure 7 schematically illustrates a detail of the second embodiment of the temperature measuring means implemented by the device of Figure 6; FIG. 8 schematically illustrates the measurement principle implemented by the second embodiment of the measuring means; - Figure 9 schematically illustrates the use of RFID devices by the second embodiment of the measuring means; FIG. 10 illustrates the electrothermal model of the connector and of its environment used by the control module of the device for estimating the contact temperature; FIG. 11 illustrates a block diagram of the module for diagnosing and estimating the contact resistance of the device; FIG. 12 illustrates a schematic diagram of the diagnostic sub-module of the diagnostic and estimation module; FIG. 13 illustrates an example of simulation of three residues obtained from the state representation (electrothermal copper track + tongue + contact point + cfip + wire) using the dynamic parity space method; FIG. 14 illustrates the standardized average of the squares of the three residues, calculated over a sliding window of 4 seconds; FIG. 15 illustrates an example of an alarm decision test; FIG. 16 illustrates a block diagram of the diagnostic sub-module of the diagnostic and estimation module; FIG. 17 shows the tab, contact point and clip temperatures simulated from the non-linear model of the electrothermal chain (copper track, tongue, point of contact, clip, wire); FIGS. 18a and 18b show the simulation of a protocol varying the electric current in the contact of 1 Ampere (1 A) for several values of the contact resistance; FIG. 19 illustrates the general non-linear model that makes it possible to estimate, in particular, the temperatures of the contact points Tmt; FIG. 20 illustrates the block diagram of the switching algorithm between the normal mode and the protection mode of the device; FIG. 21 illustrates the block diagram of operation in protection mode; FIG. 22 illustrates a variant of the first embodiment of the temperature measuring means; - Figure 23 illustrates another variant of the first embodiment of the temperature measuring means; and - Figure 24 illustrates yet another variant of the first embodiment of the temperature measuring means; FIG. 25 illustrates a variant of the second embodiment of the measurement means using an RFID measuring device between two adjacent tabs for each measurement; FIG. 26 illustrates another variant of the second embodiment of the measuring means in which the thermistor is directly connected to the rest of the RFID measuring device by a wire; and FIG. 27 illustrates yet another variant of the second embodiment of measurement in which a thermocouple is used in place of a thermistor.

Figure 1 illustrates the method according to the invention and its implementation means presented in the form of a block diagram.

These means comprise: a temperature sensor able to measure the ambient temperature near the connector; measuring means able to measure the temperature near the point of contact; · Ν.ν ·· · ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · diagnostic module capable of monitoring changes in contact point contact resistance ; a MOSFET electronic switch controlled in pulse width modulation (PWM) mode according to a predetermined period and a variable cyclic ratio, and capable of measuring the current flowing in. the point of contact to which it is connected; and a control module capable of determining and transmitting the value of the duty cycle according to the data of the temperature and current sensors according to the invention.

In a first step, the value of the electric current delivered by the controlled MOSFET, the temperature close to the contact point delivered by the temperature measuring device, and the ambient temperature delivered by the temperature sensor; are used by the diagnostic module and. 'L estimation in ·:! ::; to detect in real time a fault on the contact resistance; However, the value of the contact resistance is determined by a particular test protocol initiated at the start of the vehicle.

The diagnostic and evaluation module triggers an alarm when a fault is detected on the contact resistance.

In a second step, the same temperature information (ambient and near the contact point) and current, as well as an electrothermal model simulating "thermally" the various components of the connector and its environment (copper track, tongue, point of contact, clip, electrical wire and ambient air) are emitted by the module. .Controller.

The control module .comporte ,, a temperature estimator. which transmits the temperature of the point of contact to a regulator. ; The estimator is based on the electrothermal model: 'which is recirculated; by the value of the contact resistance estimated and transmitted by the module:;,,,, diagnostic and estimation.

If the estimated temperature Tvsi of the contact point exceeds a determined threshold T / m, the control module activates protection means to limit the electric current flowing in the contact.

To do this, the protection means use the regulator of the control module to calculate a duty cycle a and transmit it to the piloted MOSFET which chops the electric current via a PWM control command (Pulse Wide 'Modulation);''; :: ::: '

When the protection is inactive, the duty cycle a is equal to 1 (PWM mode deactivated) and the load imposes the electric current. The piloted MOSFET can then be perceived as a multi-threaded device. "

In a first embodiment of temperature measuring means closer to the contact points, illustrated in FIG. 2, to FIG. 5 ,. the. method according to the invention advantageously exploits a device described in, the. Document FR2956253 entitled "Connecting device with additional thermal coupling (s) and" corresponding "wiring harnesses, for diffusing a portion of the heat generated at a contact to an auxiliary wire. Thus, this device may be able to cool (or even reheat the need) an organ (motor, battery, connector, alternator, etc.) when it is placed close to said body. remove heat at the connector by means of a radiator wire crimped in the same female contact as the wire connected to a load (double sertissagô): - L:; v: ;; - v;: / - L ·; - ·; · · ;;

In the ideal case, no current flows through the radiator wire, so it is not subject to the Joule effect and contributes to the cooling of the functional wire which is connected to a load.

The method according to the invention consists in integrating, on the radiator wire, a component of the CTN (Negative Temperature Coefficient) thermistor type and whose particularity is to be able to deduce the value of its temperature thanks to the knowledge of its electrical resistance.

FIG. 2 represents the side view of the connector, base and nested clip holder, in which the functional electrical wires FF arrive in the clip holder POC which is itself mounted on the base EM. Each FF wire is crimped with a double DS crimp on a clip C and associated with an auxiliary cooling wire FR. The connection of the clip C and the tab L forms a point of contact PC. The tongue L leaves in the open air before crossing the printed circuit Cl and is soldered on the other side of the printed circuit S.

CT temperature sensors are arranged on the FR cooling wires when they are in the open air and as close as possible to the connector.

Figure 3 illustrates the concept more closely. The CT sensor (in this case a CTN resistor) is soldered near the double crimping DS on a stripped portion of the cooling wire FR and contained in an insulating sleeve M1. The functional thread FF is not modified.

In order to determine the resistance R 1 of the NTC thermistor, the invention proposes a voltage divider type circuit. For this, it is necessary to have: - a CTN thermistor whose resistance is sought to determine; - a simple resistance fit whose value is known and correctly sized to minimize the Joule effect in the radiator wire; - the voltage across the single resistor is read and transmitted to a receiver using an RFID chip (Radio-identification, more often referred to as the RFID symbol - from the English Radio Frequency Identification - is a method for memorizing and retrieve data remotely using markers called "radio tags" - "RFID tag" or "RFID transponder" in English).

By considering the diagram of FIG. 4 'where:% is a known resistance and the value of which is sufficiently large compared to the resistance of the load [il] so that the current flowing in the radiator wire FR is negligible compared to current flowing in the functional wire FF ;. b ffcr * is a thermistor whose resistance is sought to be measured is the voltage across the resistor Rt measured and transmitted by the'RFID 'chip [Vf' .y + vest the battery voltage and assumed to be accessible in real time b On deduces from the divider bridge the expression of the voltage vt:

(1) from which the value of the resistance is deduced

Each device which is to be monitored and which is provided with double crimping is equipped with an "RFID measuring device". A receiver acquires the voltage Vt of a single "1" RFID measuring device at a given instant (see FIG. 5).

In a second embodiment, illustrated in FIGS. 6 to 9, the method according to the invention implements measuring means based on a NTC thermistor type component, welded or brazed to the corresponding tab, and whose value of its electrical resistance varies according to its temperature, acting as a sensor.

Figure 6 shows the side view of a connector. The electric wires F arrive in the clip holder POC which is itself mounted on the base EM. Each wire is crimped with a cloth G which forms a PC contact point at its connection with a tongue L. This tongue comes out in the open air before crossing the printed circuit Cl, then is soldered on the other side of the circuit board S. The CT sensors are attached to the L-tabs when they are in the open air (Figure 7).

As for the first embodiment, to determine the resistance value of the NTC thermistor, the invention proposes a voltage divider type mounting. For this it is necessary to have: -: -: - ::; -:; v:; / :::; v: --'- ";'of a CTN thermistor whose resistance is to be determined; simple bed whose value is known and correctly sized; - ::: - of ün'.language of mass common to all measurements.

The voltage across the single resistor will be read and transmitted: / to: a receiver with an RFID chip. :::::::/ - / ^^ For this, consider the scheme of Figure 8 where:% is -Une / known resistance and sufficiently large compared to the load resistance L - 'j: η.σβ is a thermistance, and one tries to measure the resistance M; /// 'vt is the voltage at the terminals of the resistor Rt measured and transmitted by the chip / RFID [F]; : // :::;:; :: .//V'PV is the voltage of the battery: and it is accessible in time. voltage ^ c

(3) from which the value of the resistance is deduced

(4)

Each tab to be monitored is equipped with a RFID measurement device 1 and 2. A receiver acquires the voltage Ff of only one of the two; ;. '. ..

"FS-V'dô devices measure RFID '(D: fepesitf dexitesiii''to''''''''{JI! ErwirJ? 11pucè; REiiûjjH) to a given instahti': (the diagram of principle is'donne ( Figure 9).

An elemtrothermal model is introduced hereinafter, and a model of; ... fault on contact resistance with reference to FIG. 10,

Knowing: The temperature of the thermistor can then be determined. If the temperature measurement is made at a distance sufficiently close to the point of contact, then the temperature variations at the thermistor directly translate those of the point of contact Thanks to an electrothermal model previously defined according to the type of connector used as well as its environment, it is possible to estimate the temperature of the contact points and to detect the abnormal variations of their contact resistance. If the sensor detects an abnormally high temperature, it must be ensured that the fault causing this overheating comes from the sensor. increase of the contact resistance Thus, it is assumed that two faults are possible which can lead to abnormal heating at the contact: the first is an increase in the contact resistance which causes an increase in the Joule effect at the level of the contact. contact and therefore an increase in temperature; the second is an excess heat flow injected elsewhere in the circuit (for example, a fault would heat up abnormally near the sensor ··; ·: ^ ';··';;; ·. '··' - · '.··;temperature).;::..

To make a decision about the origin of the defect, a model-based diagnosis is used: dynamic parity space method (Ding, 2013): ·;: ;;;. ';.':;:

In order to be precise enough, the configuration of the environment -. (case, electronic board, beams, ...) of the point of contact must be taken into account in the model which admits as measurable inputs, the current and the ambient temperature. The electrothermal models of the point of contact and its environment are based on the thesis of Huy Cuong Nguyen (Nguyen, 2013).

The general model is compact, easily implantable and consists mainly of linear or non-linear first-order differential equations. When this model is linearized around an operating point and is sampled, it can be in the form of a discrete state representation:

where: A denotes the state matrix; J.:'designation:ta'matriœ canceled; > · · 'd d d matrice matrice matrice matrice matrice matrice matrice; f is the matrix of non-measurable inputs; K denotes the defect direction matrix; M denotes the measurement noise matrix; ·. :::: * (*) denotes the state vector; ] r designates the input vector (/ is the current, at room temperature); d (k) denotes the vector of disturbances and measurement noises; and ':;::;';';;:' é / (ife] i 'designates the vector of amplitude of defects νο-ό Remarks:

The vector x (Jc) contains at least the temperature rm (k) measured by the sensor near the point of contact. The output of the model is the temperature rm (fc);

The vector d (fe) contains non-measurable exogenous inputs, for example additional injected heat flows from non-modeled superheated components. It also contains measurement noise from the sensors.

To aid understanding, an electrothermal model of a chain of "elementary" components, which includes: - a copper track; - a tongue; - a point of contact; - a clip (without double crimping to simplify); - an electric wire.

These elementary components are modeled separately and they are arranged between them to form the electrothermal chain. The thermal exchanges between the elementary components as well as with the environment (ambient air) are shown schematically by arrows in Figure 10 · ::

The electrothermal behavior of each of the elementary components is governed by a first-order differential equation or by a static equation (in the case of the point of contact) obtained by applying the first principle of thermodynamics. Four physical phenomena are likely to occur, including an electrothermal phenomenon which is the Joule effect (thermal manifestation of the electrical resistance to the passage of an electric current), and three thermal transfer modes which are: (exchange; :; '^ ^ ^û î' - - - - s s - - - - - - - - - -::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ '''''''''''''''''''''''''''''''. The: nomenclature used then the equations governing the electrothermal behavior of each elementary component are given below.

Nomenclature: ^ denotes thermal conductance in W / K; '/ denotes the electric current at A; / "Denotes the temperature of the component χ in K; G * denotes the thermal capacity of the component x in J / K;

Rx denotes the electrical resistor of the x component in Q; the index made reference to the copper track; the index l refers to the tongue; the pc index refers to the point of contact; the index c refers to the clip; '.'.'.'.'.''''''''''''''''''''''''''''''''''''''''''''''' index - indexed to the electric wire ·; · - the amb index refers to the atmosphere. ... The equations used · to model the different components are. given below:

Copper track:

Tongue'·:/;;·;·'/····'·'··'·;·'.;·'.

(7)

Point of contact: 8)

Clip: (9) /; /; / FiLectric:

Ί0) where is a non-linear function of Tf and T "^.

Equations (6) to (10) constitute a non-linear model of the electrothermal chain and are used by the contact point temperature estimator (see below the description of the control module for the protection of a point of contact). The purpose of the diagnosis is to detect in real time a change in the resistance of the drug compared to its nominal value. The vector of amplitude of the defects chosen is given by:

where ΔΙ? __ is the difference between the value of the contact resistance in the JW? nominal case and in the case of a defect. Only the matrix B is affected thus the defect direction matrix is:

(12)

Assuming that there is only a noise% on the measure by linearizing equations (6) to (10) around a point 'of: functionally and by λ'Choosing as the state vector Ά% 7 / F , as input and as output y == ¾1. we get the '' state representation. ";: next :: ';: ..

where GS1 and 6S2 are the linearized terms of G5 {Tf, Tam} t) respectively with respect to 1} and with respect to: :.

Finally, there remains only to: sample: the '''model'.'' (I3) '''to put it in the form of a discrete state representation in accordance with the general model (5). The function of the diagnostic module and the contact resistance estimation module -with reference to Figure 11.//

The diagnosis and estimation module of the contact resistance consists of two submodules. The first is the diagnostic sub-module of the contact resistance operating in real time. Its role is to detect a variation of the contact resistance from temperature measurements (ambient: and near contact point 7 ^) and current: /. If a too large variation of the contact resistance is detected with respect to the nominal case, an alarm is triggered and the second sub-module will be activated at a next power up to estimate the value of the contact resistance. ./

The second sub-module aims to estimate the value of the contact resistance epe and will only be activated if the 'diagnostic module'. triggers an alarm. This second submodule 'requires a special test protocol for the next power-up' to identify the contact resistance, in order to operate it requires, among other things, the same temperature and temperature measurements. of the current as the diagnostic sub-module. ': -': ;; :::::; - '''-' - presentation of the diagnostic sub-module / '' of there '' / contact resistance is made below: // ./- '/. / /: From the matrices and signals of the state representation, whereas a discrete linearized general model (5), a residue vector is generated such that it is the most sensitive to defects and the least sensitive: to the state, to the inputs, the control and to the disturbances The diagnostic method used is that of the space of parity dynamic which is · a 'method called / to' / '/ base, of model. The residue generating block has as "inputs" the measured /: signals Jz, Tm and TamA and outputs the residue vector (see FIG. 12).

The equations of the residue generator are determined by making '' appear ''; temporal redundancies' from the measurements. These temporal redundancies are obtained by deriving * the output y on an observation horizon [k, fc 4 * s] (s is the number of samples corresponding to observation )οΓίζοη): - 'Ëri' shifting this horizon on [k - s, k] (use of past samples), counter:

sought is to create a residue signal independent of the state 2t, robust vis-à-vis the disturbances d. Since the signals λ and d are partially or not at all known, by multiplying on the left the equation (14) by a vector w different from 0 such that wOs = û and ν? Φ2 = 0 (very numerous software: Matlab , Octeve, Scilab, ... allow to find a vector), we obtain:

The residue r is chosen

Thus r is equal to 0 when there is no fault otherwise, its drift and becomes non-zero. Finally more residues are obtained by creating other vectors satisfying the same properties as the vector w. These vectors are then concatenated to form a matrix w. In this case the residue vector becomes:

The diagnostic sub-module corresponding to equation (17) above, is implantable in a very simple and inexpensive way in computing time since the residue> is a simple linear combination of y-measures and orders u present and past. Its implementation therefore requires only elementary operations of addition and storage type.

In order to choose whether an alarm should be triggered or not, a decision test must be made on the residue. One can imagine simple decision-making algorithms. For example, an alarm may be triggered when the residual exceeds a threshold, or when its average (or variance) on a sliding window exceeds a threshold.

There are also more complex decision tests. For example, some decision tests are based on probability and maximum likelihood laws: Wald test, Student's test, GLR test.

A schematic diagram of the diagnostic submodule, consisting of the residue generator and the decision test, is given in FIG. 12 and an example of simulation of three residues obtained from the state representation (11) (electrothermal chain copper track + tongue + point of contact + clip + fit) using the dynamic parity space method is given in figure 13.

The peaks represent abrupt variations of the contact resistance: the agitation comes from the measurement noise which is taken into account during the simulation. The sampling period is 0.25 seconds.

The normalized average of the squares of the three residues is calculated over a sliding window of 4 seconds (see Figure 14). The decision test for this example is deliberately very basic, if the normalized average is greater than 0.1 the alarm goes off and goes to 1 otherwise it remains at 0 (see figure 15)

The submodule presentation: estimate of the contact resistance is made below.

The static parity gap diagnosis detects the occurrence of a fault on the contact resistance in real time. However, although it detects variations of the contact resistance, it does not allow to directly translate them by a value of the contact resistance Rpc

Thus, a simple protocol is proposed to identify the value of the contact resistance at the stop of the vehicle.

This protocol uses a calibrated current step sent to the point of contact whose resistance is to be estimated; ·:; Χ: ··: ν ·;: ;;; - ν ;; · ΐ3'ΐΓηβ8υΓ8 of the temperature near the point of contact 7m; the measurement of the ambient temperature r_ "3. : - a high-pass filter.

The temperature rise dynamics of a point near the contact point are characterized by time constants related to the different heat fluxes generated at the time constant. linked to the flow of o o '. The heat generated by the contact resistor (RptJ2) can be determined at the beginning by simulations (from the non-linear model of the connector) or by tests (Chelbi, 2014). This time constant, noted v, is shown to be the smallest (therefore the fastest) with respect to the other time constants related to the heat fluxes generated near the point of contact.

Thus, a high-pass cut-off filter equal to fc-1 / τ is used to filter the temperature measurement near the connector. Lesigrtal at the output of the high-pass filter, to which the measured value of the ambient temperature is subtracted, no longer varies as a function of the contact resistance and the current. The idea is therefore to use a calibrated current step and to analyze the response of the high-pass filter which will pass through a specific maximum to the value of the contact resistance Rpc (see example described below).

A schematic diagram of the sub-module for estimating the resistance

'''''''''''''is given in figure 16. V; V

Fig. 17 shows the tab temperatures T1, from point dd; pcontact Tpc and 'Te clip simulated from the nonlinear model of the electrothermal chain \ (track of "copper, tab, point of contact, clip, wire), the electric current remaining constant, at r - 400 seconds the contact resistance is multiplied by 3. Assuming that the temperature measured near the contact point is directly on the clip, there constant time τ (that is to say the time it takes for the temperature of the clip to reach 63% of its final value starting from a given initial value) taken from the simulated temperature of the clip is approximately equal to 20 seconds,

The cutoff frequency chosen for the high-pass filter is therefore equal to f = ι / τ = 0, QS Hz.

Figures 18a and 18b show the simulation of a protocol varying the electric current in the contact of 1 Ampere (1 A) for several values of the contact resistance. The maximum of the filter output changes depending on the value of the contact resistance. Thus, a mapping associating a maximum of the response due to a contact resistance makes it possible to estimate the latter. When the estimated value of the contact resistance is greater than a determined threshold considered dangerous, an alert warns the driver and maintenance maintenance of the connector concerned must be performed. The algorithm for point-of-contact protection is described below: illustrates by a schematic diagram, the general non-linear model which is implanted in a calculator and which makes it possible to estimate in particular the temperatures of the contact points Test.

When an alarm is triggered for a given contact point, the general model is recalibrated with the update of the estimated contact resistance tors of diagnosis; The contact point protection algorithm is based on that for the protection of an electric wire described in FR2990807 (GuiflemardetaL,: 2013). any contact i, a protection will be triggered if its estimated temperature exceeds a maximum limit value T ^ lm determined regardless of the ambient temperature and regardless of the current if there is no short-circuit franc. The return to normal operation will occur if the estimated temperature falls below a threshold temperature determined to be lower than the limit temperature (see Figure 20). 7.::::::- :.

When the algorithm: is in normal operating mode the load imposes the current transistor, can then be seen as a simple wire ..... . In the event of a short-circuit, the power failure is immediate "a fault. . is counted and a vehicle level alert is generated. The transistor / can then be rebooted according to the programmed logic. :

A diagram of the operation in protection mode is given in: figure 21.

When the protection '.' Is 'active: (¾.' · The controller calculates a duty cycle m (a - t in normal operation) and transmits it to the piloted MOSFET which switches to PWM control, from the contact point i to the value if the electric current is too high.Thus, the controlled MOSFET makes it possible to reduce the rms value of the electric current by chopping it via the PWM mode, which makes it possible to limit the Joule effect generated in particular by the contact resistance.

Finally, the choice of the sampling periods and the implementation of the protection algorithm are based on the document FR2990807 (Guillemard et al., 2013). For example: variants of the temperature measuring means described above with reference to FIGS. 2 to 5, illustrating the first embodiment of the temperature measuring means, it is possible:

to replace the splitter bridge by a Wheatetone bridge in the RFID measuring device; to replace the NTC thermistor of the measuring device with the RFID measuring device by a

These variants are presented in the following points.

In a first variant, a Wheatstone bridge is used in place of the voltage divider in the RFID measuring device

The divider bridge of the RFID measuring device can be replaced by a WheâMone bridge using the CTN thermistor and three other bi-dimensioned resistors

Figure 22 shows the block diagram of the Wheatstone bridge.

The resistors and g are equal, the RFID chip measures the difference in tenon between Vt and F2. Assuming that the battery voltage V + is accessible in real time, the resistance is determined using lali & P forrhufeauivante::

a second variant, PmpéWtTitiser a PTC thermistor instead of a resistance CTN. For use of a PTC thermistor instead of a CTNv 'thermistor. the . principle is. the same as Figure 4, just replace the resistance; CTN by one; CTP resistance.

In a third variant, a thermocouple T may be used in place of the RFID measuring device.

Fig. 23 shows the use of a thermocouple T for each measurement. The measured thermocouple T + and T- son of the thermocouple T are welded after the double crimping DS on a stripped portion of the cooling wire FR, between the free end of the cooling wire and the double crimping DS. The thermocouple T is contained in an insulating sleeve Ml. The functional thread FF is not modified.

The presence of an RFID measuring device is no longer necessary since the measurement is made directly by the thermocouple T. This solution increases the number of wires for the measurements (two wires per thermocouple).

A variant of the previous case may be considered (Figure 24). Indeed, it is possible to glue the measuring wires T + and T- of the thermocouple T directly on the double crimping DS. In this configuration, neither the functional wire FF nor the cooling wire FR are modified.

The presence of an RFID measuring device is no longer necessary since the measured is directly made by the thermocouple. This solution increases the number of wires for measurements (two wires per thermocouple). ..A.Title of the means for measuring the temperature-described; FIGS. 6 to 9, illustrating the second embodiment of the measurement mode: "temperature" It is possible: .vg ::.:; '; -g: 7 ::::: v.;> to replace the diverter bridge by a Wheatstone bridge in the ':: ··': · 'measuring device'RFID;'.'''''''''''''''''''''''''''''''''''''''''''''''''''''''':'''''''''''''''''''': to replace the NTC thermistor of the' safe 'device: · /. ; RFID by a PTC thermistor; : ggrg: gGG ·· - to place the RFID measuring device between two adjacent tongues; - connect the thermistor · .the remaining (resistor.'measurement + chip "RFID) of the RFID measuring device by a wire - replace the RFID measuring device with a thermocouple - perform combinations of points which previous.

These variants are presented in the following points.

In a first variant of these second measuring means, like that of the first measuring means (FIG. 22), a Wheatstone bridge may be put in place of the voltage divider in the device; y de-measure RFID. determine the resistance

In a second variant, similar to that of the second embodiment of the measuring means, it is possible to use a thermistor. : v. CTP instead of a CTN thermistor. For use of a thermistor; In place of a CTN thermistor, the principle is the same as FIG. 7, it suffices to replace the CTN resistor. by a PTC resistor. In a third variant, one can use a thermistor between ggg :. two adjacent tabs .; . .

Figure 25 shows the user of the RFID "measuring device" between two adjacent tabs for each measurement. measurement: g.: ..... RFID DM is wound between two adjacent tongues L1 and L2 The first tongue L1 is that of a point of contact to be monitored and in which an operating current flows, the second tongue L2 is connected to the mass.

This variant requires a pair of adjacent tabs for each measurement. There are therefore as many ground tabs as measurements to be made instead of a single ground tab (see Figure 9).

In a fourth variant, the thermistor is directly connected to the rest of the RFID measuring device by a wire.

Fig. 26 is a diagram of the placement of the temperature sensor on the connector tabs. A terminal B1 of the thermistor Th is soldered to the tongue L of a contact point to be monitored and in which an operating current flows. An electric wire FM connects the other terminal B2 of the thermistor Th to the rest of the RFID measuring device RDM. The rest of the RFID measuring device denotes the resistance Rx and the RFID chip (refer to FIG. 8). The measuring wire then returns to ground M.

This variant adds as many wires as there are thermistors.

In a fifth variant, a thermocouple is used instead of a thermistor.

Figure 27 shows the use of a thermocouple for each measurement. The thermocouple T is soldered to the tongue L of the point of contact to be monitored. The thermocouple measurement leads T + and T- are connected to a measuring device.

The presence of an RFID measuring device is no longer necessary since the measurement is directly made by the thermocouple. This solution increases the number of wires for the measurements (two wires by thermocouples). Other variants can be envisaged by combining some of the variants presented above. For example it is possible to place the RFID measuring device between two adjacent tabs in which the CTN resistor is replaced by a PTC resistor. The other combinations are not intentionally presented not to overload this document and because they are easily understandable.

The advantages of the invention are the following: λ. Ensure the thermal protection of the contact point, even when the current remains the same: that is, when the '.' :: Resistance of contact increases; : - diagnose and detect dangerous variations of the presence of: '''contâct.pour to perform maintenance at the earliest'. :: νν »estimate · :: the value of a resistance v; 'dë;<x> h ^ calibrated · current change and a high-pass filter. :::. 0 -: / 0 dd '· - avoid or limit'.location of the protection device because to the MOSFET driven can be rebooted: 'at one .......: vv · fuse must be changed once it has melted; :. improve. the double crimping device. thanks to. the synergy of a cooling method with a built-in temperature measurement device. . - use c: simple electrothermal models and compact enough to be implemented in real time; to discriminate the overheating contact points from the "normal" temperature contact points with the possibility of acting only on the electrical lines for which the point of contact has a fault. MFEE-m ·: · · · -

Bibliography:

Bavoux, I, &amp; Guiliemard, F. (2012). Device for connection to the auxiliary wire (s) of thermal OTüplage, wiring harness and use thereof. France (FR2956253). (2014). Electrothermal modeling of electrical conductors in the automotive field for estimating variations in the resistance of a contact point. University of Bordeaux. ; \ - ::: - ;;;;; - '^ - Ôà: Crüz ^ reira, S., Maudemain, A., &amp; Faure, M. (2012). Protection of an electrical outlet against temperature. La France. (FR2968475) ## STR2 ## <2013). Model-Based Fault Diagnosis Techniques (2nd ed., P.501). Springer.

Graridvuillemin, J. (2009). Study of the electrothermal phenomena governing the supply lines of a car electrical network-Application to the dimensioning of the electric beams and their protections. University of FRANCHE-COMTE. Grannov, J. (1966). Contact of nominally fiat surfaces. Proceedings of the Royal Society of London. Serials A, Mathematical and Physical Sciences,: 300-319,

Guillemard, F., Bavoux, B., Nguyen, HC, Nocquet, C., Pavera, G., Cloup, JP, Sabatier, J., Moreau, X. (2013). Electronic device for protecting an electrical conductor and method for controlling a device . device. La France. (FR29908Ô7)

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Singer, M .; &Amp; éKsh0n2e,. K. (1991). Electrical resistance of random rough contact surfaces using fractal surface modeling. In Electrical ... Contacts, 1991. ProOeedings of the Thirty-Seventh IEEE Holm Conference on (pp. 73-82), Kanata, Canada. - d '. "Tlistani, L. (2000)" Reliability of electrical connectors subjected to vibrations University of Paris Orsay.

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Claims (11)

1. A method of protection against over-heating and / or over-current of an electrical connector (POC, EM) comprising at least one contact point (PC), characterized in that it consists of: (i) measure the ambient temperature (7ramb) near the connector (POC »EM) and the temperature (Tm) near the contact point (PC) of the. connector (POC »EM); ή; .. · .. '. (ii) measuring the intensity (i) of the current flowing in the contact point (PC); (iii) to set the contact resistance (Rpc) of the contact point (PC) from the measurement of the ambient temperature (7 ^), of the temperature (Tm) near the point of contact (PC) of the connector (POC, EM) and the intensity (ί) (ί) of the circumcircularity in the point of contact (PC); (iv) to determine the temperature of the contact point (Test) from an electrothermal model of the component chain comprising the connector (POC, EM) and its environment, which model is flunked by the value the estimated contact resistance (Rvc); and (v) from the temperature (ΓαΛώ and Tm) and current (i) measurements and if the change in the contact resistance (?ΓΛώ) is greater than a nominal reference value ss à à à à déclen déclen déclen déclen à »......... 2. Method according to the preceding claim, characterized in that '' .''ervist é'lervé: (y) to exploit the same information of ambient temperature (T ^ ") and :: proximity of the point of contact (7 ^) of current (i), for limiting and regulating the circulant in the contact point (PC) if the temperature of the estimated contact point (Tgst) is greater than a limit temperature (T £, J determined. 3. Method according to the preceding claim, raciérisé in that it consists, to limit and regulate the current (t) flowing in the contact point (PC), chopping said current (i) in a duty cycle (a). ) determined and variable until the temperature is below a specified threshold temperature (T ^ mM), 4, Method according to the preceding claim, characterized in that the duty cycle is equal to 1 when the estimated temperature (f "t) remains lower than or equal to the limit temperature ('/ yiw); the electric charge present on the point of contact (PC) imposing the electric current (i). 5, Device for implementing the method according to one of the preceding claims, characterized in that it comprises: - a temperature sensor adapted to measure the ambient temperature (Tamk) near the connector (POC, EM); measuring means capable of measuring the temperature (Tm) close to the point of contact (PC); a diagnostic and estimation module, able to monitor the variations of the contact resistance (RpJ of the contact point (PC), and to estimate the value of the contact resistance (RpJ of the contact point (PC); an electronic switch, of the MOSFET type, controlled in pulse width modulation mode according to a predetermined period and a variable duty cycle (a), and capable of measuring the current (i) flowing in the contact point (PC) at which it is connected, and a control module able to determine and transmit to the switch, at regular intervals, the value of the duty cycle (a) calculated from the data of the temperature sensors (Tamè and Tm) and of the current ( i) 6, Device according to the preceding claim, characterized in that the control module comprises a temperature estimator which transmits the estimated temperature (Test) of the contact point (PC) to a regulator; the estimator based on the electrothermal model which is recaled by the value of the contact resistance (Rpc) estimated and transmitted by the diagnostic and estimation module. 7. Device according to one of claims 5 or 6, characterized in that the measuring means comprise an auxiliary wire strand (FR) of predetermined length, crimped by double crimping (DS) with the functional wire (FF) by which circulates the electric current (I) and whose common ends are connected near the point of contact (PC); said auxiliary strand (FR), initially provided as a radiator wire, being provided with a CTN or CTP (Rctn) thermistor component placed in series between the contact point (PC) and a reference potential, able to deduce its own temperature from the value of its electrical resistance. 8. Device according to the preceding claim, characterized in that the measuring means implement a voltage divider bridge having a resistance - '(JEj) of determined value and dimensioned to minimize the Joule effect in the radiator wire (FR) , placed in series between the CTN or CTP thermistor (| f) and the reference potential, and a chip R; FID located at the terminals S; the resistor (Rt); iia said RFID chip being adapted to transmit the voltage (V1) read across the resistor (lt) to a .receptor. . .. .t .9. : Device according to the preceding claim, characterized in that the divider bridge is replaced by a Wheatstone bridge. . 1: 0, Device according to one of the claims.vSFou 6, characterized enipf; that the measuring means include: An auxiliary wire strand (FR): of determined length by double crimping (DS) with the functional wire (FF) through which I. current: electrical (i) and whose common ends are connected near the point of contact (PC); said means being provided with a thermocouple (T) whose pair of measuring wires (T + and T) are either soldered on a stripped part of the radiator wire (FR) near the double crimping (DS) or directly glued on the double crimping (DS). 11. Device according to one of claims 5 or 6, characterized in that the measuring means comprise a thermistanu type component CTN or 'CTP (&amp;#), welded or brazed on a tab corresponding to a point of contact, close to the point of contact, and able to deduce its own temperature ·; starting from the value of its electrical resistance; the component being welded or brazed on the tongue when it is last free. 12. Apparatus according to the preceding claim, characterized in that the means of measurement measure a divider of voltage comprising a determined resistance (%) of which one. first terminal is coupled to a tab to be monitored and whose second terminal is coupled to a CTN thermistor ·· 'Or' · 'ΟΤΡ (Λ; τί?) set in series between the thermistor and another determined tab, reference potential, common to all measurements, and an RFID chip disposed across the resistor (Rt), the said RFID chip being able to transmit the voltage (¥ 1 ) read across the resistor (Rt) to a receiver. 13. Device according to the preceding claim, characterized in that there are as many potential reference tabs as tabs to monitor; a reference tab; being adjacent to one of the tabs 5 and 6, characterized in that the measuring means comprise a thermocouple (T) of which the measures (T + and T-) are welded or brazed on a tab corresponding to a point of contact, close to the point of contact. .