FR3077688A1 - METHOD AND DEVICE FOR DETECTION AND IDENTIFICATION OF A HEAT SOURCE EXCEEDING A PREDEFINED TEMPERATURE THRESHOLD - Google Patents

Abstract

A device for detecting a temperature threshold by a heat source from a plurality of heat sources, the device comprising a plurality of components connected in series and each having a variable electrical resistance as a function of its operating temperature, each component being able to be thermally coupled to at least one heat source, the variable electrical resistance then having a high value when the temperature of said heat source is greater than or equal to the temperature threshold, the device further comprising a plurality of resistors having distinct resistance values, a resistor being connected in parallel parallel with each component, so that when the variable electrical resistance of a component is of high value, the equivalent resistance of the electrical chain formed by the components and resistors presents a v distinct value for each parallel connected resistor characteristic of this component and of the resistor connected to it in parallel.

Description

METHOD AND DEVICE FOR DETECTION AND IDENTIFICATION OF A

SOURCE OF HEAT HAVING EXCEEDED A PRESET TEMPERATURE THRESHOLD

FIELD OF THE INVENTION

The invention relates to devices for monitoring the temperature of heat sources, and more particularly to devices for monitoring comprising electronic components having a resistance which varies with the operating temperature.

CONTEXT OF

THE INVENTION

The present invention provides a device for detecting the temperature overshoot of one or more heat sources allowing the temperature threshold monitored to be adjusted.

Document CN102195270 discloses a device for monitoring the temperature of several heat sources, consisting of battery cells. The device comprises a plate having a variable volume with the temperature.

The plate is placed against a wall of the cell to be monitored. In the event of overheating, the plate swells and mechanically actuates a switch arranged opposite said plate, the opening of the switch interrupting the passage of a load current in the cell.

However, this solution has only one adjustment of the overheating temperature threshold, at a distance between the plate and the switch; it parameter knowing the is therefore configurable only during the manufacture of the module comprising the cell or cells to be monitored, then it is frozen. The value of the monitored temperature threshold can no longer be adjusted. In addition, it causes the abrupt disconnection of the cells, no other corrective measure can be envisaged.

Therefore, there is a need for a device for monitoring the temperature of one or more heat sources, allowing adjustment of the monitored temperature threshold.

To this end, the invention aims to provide a device for detecting that a first predefined threshold of a temperature has been exceeded by at least one heat source, the detection device comprising at least one component having a variable electrical resistance as a function an operating temperature of the component, an electrical energy source capable of supplying an electric current flowing through said component, said component being able to be thermally coupled to said heat source, so that the operating temperature varies as a function of the temperature of the heat source and of the heat given off by the Joule effect in the component when it is traversed by the electric current, the variable electric resistance having a high value if the operating temperature is greater than a second predefined temperature threshold , said trigger threshold, the electrical energy source being configured e to generate the electric current so that the operating temperature is greater than or equal to the trigger threshold as soon as the temperature of said heat source is greater than or equal to the first predefined temperature threshold, the variable electrical resistance then having the high value.

According to preferred embodiments, the detection device comprises one or more of the following characteristics which can be used separately or in partial combination with one another or in total combination with one another:

The detection device is electrically isolated from the heat source.

In the detection device, the source of electrical energy is a source of current.

Electric current is supplied in the form of periodic pulses, with a fixed or variable duty cycle.

The device is configured to detect that a first heat source is exceeded by a heat source among a plurality of heat sources, and it comprises a plurality of components in the form of a plurality of resettable fuses, each resettable fuse being thermally coupled at least one heat source, the fuses being connected in series.

The device further comprises a plurality of resistors, each having a distinct ohmic value, a resistor being connected in parallel to the terminals of each fuse.

The at least one heat source is a battery cell.

The device further comprises a monitoring module configured to trigger a correction or signaling action when the resistance of one of said components exhibits the high electric variable value.

The invention also relates to a device for detecting that a first predefined threshold of a temperature is exceeded by a heat source from among a plurality of heat sources, the detection device comprising a plurality of components connected in series and each having a variable electrical resistance as a function of a respective operating temperature, the variable electrical resistance having a high value if the operating temperature is greater than a second predefined temperature threshold, called the triggering threshold, and a low value otherwise, each component being able to be thermally coupled to at least one of the heat sources, so that its operating temperature is greater than or equal to the triggering threshold as soon as the temperature of said at least one heat source is greater than or equal to the first predefined temperature threshold, the resistance variable electrical resistance then having the high value, the device further comprising a plurality of resistors having distinct ohmic values, a resistor being connected in parallel across the terminals of each component, so that when the electrical resistance of a component has the high value, the equivalent resistance of the electric chain formed by the components and the resistors has a characteristic value of this component and of the resistance which is connected to it in parallel.

a

The source invention also relates to a heat identification method having exceeded a first predefined threshold of a temperature, among a plurality of heat sources, the method comprising:

a step of thermal coupling of the plurality of heat sources to components of a detection device as described above, each component being thermally coupled to at least one heat source, so that its operating temperature is higher or equal to the trigger threshold as soon as the temperature of said at least one heat source is greater than or equal to the first predefined temperature threshold, the variable electrical resistance of the component then having the high value, a step of connecting the electrical chain formed by the components and resistances to an electrical power source, a step of generating a power signal by the electrical power source, a step of detecting a response signal across the terminals of the power source power supply, a step of determining an equivalent resistance of the electric chain formed by the components ants and resistances;

- a stage of identification of the component of which the resistance presents the high value, in terms of the resistance equivalent. A other object of the invention relates to a vehicle comprising a dispositi f detection overshoot of temperature as previously described. BRIEF DESCRIPTION DRAWINGS The Figures 1 and 2 represent schematically two modes of production of a device detection of overtaking of temperature arranged to monitor the temperature s respective of a plurality of cells of drums. The Figures 3 and 4 represent two devices of overshoot detection of temperature in two modes of

realization of the invention.

FIG. 5 represents the steps of the method of identifying a heat source having exceeded a predefined temperature threshold, according to an embodiment of

1'invention.

DETAILED DESCRIPTION OF THE INVENTION

In Figure 1 is shown schematically a detection device according to an embodiment of the invention. The device D is installed in a vehicle V, for monitoring the temperature of a plurality of heat sources SI,

S2,

Sj, ... Sn constituted by battery cells, grouped in Ml modules,

Mm.

The battery cells are of the flexible type, known by the English term "soft-shel1".

The device comprises a plurality of components C1,

C2,

Ci, Ck, having a variable electrical resistance R_PTC as a function of an operating temperature Tf of the component

Cl,

C2, Ci, Ck. In a preferred embodiment, the components C1, C2, Ci, Ck are in the form of a plurality of resettable fuses.

Each resettable fuse Cl,

C2, Ci,

Ck is thermally coupled to at least one heat source

IF,

S2,

Sj, Sn.

In the example illustrated in figure

1, the heat sources are battery cells, and the thermal coupling is carried out by coating each resettable fuse

Cl,

C2, Ci,

Ck of a thermal sheath, which is then fixed in contact with the battery cells. Each resettable fuse

Cl,

C2, Ci,

Ck is coupled to two battery cells, the fixing being obtained by compression and / or gluing.

The device also includes a source of electrical energy E capable of supplying an electrical current Is passing through the resettable fuses Cl,

C2, Ci, Ck, thermally coupled to battery cells

IF,

S2, Sj, Sn, so that the respective operating temperatures of the components

Cl,

C2, Ci, Ck, varies depending on the temperature

T of heat S to which they are thermally coupled, and of the heat given off by the Joule effect in the component Cl, C2, Ci, Ck when it is traversed by the electric current Is.

The variable electrical resistance of a component, in this example a resettable fuse, has a high value Rd if the operating temperature Tf of the component is greater than a second predefined temperature threshold, called the tripping threshold Td.

The electrical energy source is configured to generate the electrical current Is so that the operating temperature Tf is greater than or equal to the trigger threshold Td as soon as the temperature T of said heat source S is greater than or equal to the first threshold of predefined temperature TS, the variable electrical resistance then having the high value Rd.

The device D is electrically isolated from the heat source S. In this way operation of the device D the detection characteristics are independent of the electrical characteristics of the heat sources to be monitored: the current Is flowing through the resettable fuses has a value varying between 100 voltage delivered by the power source E of a typical value of 12 V, while the operating voltage delivered by the set of battery cells typically amounts to 400 V.

In the example illustrated, the energy source E is a current source and the components Cl, C2, Ci,

Ck are connected in series. In this way, the electric current Is does not depend on the number k of components of the device D, nor on the number n of heat sources to be monitored, which simplifies

1 adjustment of the first temperature threshold

Simply by lowering the current Is delivered by the current source E, the first temperature threshold TS is increased, and vice versa.

As already mentioned, the operating temperature of a component, in this example a resettable fuse, depends on the temperature T of the heat source

S to which the component is thermally coupled, and the heat given off by the Joule effect in the component when it is traversed by the electric current Is. Thus, for a component characterized by a given trigger temperature threshold Td, the adjustment the first temperature threshold TS reached by the monitored heat sources SI, S2, Sj, Sn, can be obtained by varying the heat given off by the Joule effect in the component.

In a preferred embodiment, the electrical current Is is supplied in the form of periodic pulses, of fixed or variable duty cycle.

The amount of heat released by the Joule effect in the component can thus be adjusted by modifying the passage time of the electric current in the component, which can be obtained simply by varying the duty cycle of the periodic pulses.

In Figure 3 is illustrated an embodiment of the detection device incorporating an electrical energy source E configured to deliver an electrical current Is in the form of electrical pulses.

In a dimensioning phase of the detection device D, a fixed duty cycle can be determined for each application, as a function of the first temperature threshold TS to be monitored, the electrical characteristics of the components Cl, C2, Ci, Ck, and the characteristics of the thermal coupling carried out between the heat sources to be monitored and these components. This duty cycle, and therefore the first temperature threshold TS to be monitored, can thus be adjusted according to the specificities of each application.

In an operating phase of the detection device D, the possibility of varying the duty cycle makes it possible to adjust the first temperature threshold TS without intervening in the installation of the device D and of its thermal coupling to the heat sources.

A punctual variation of the duty cycle after a first detection of exceeding the first temperature threshold TS, makes it possible to confirm this first detection and therefore to make the result of the detection more reliable, by sending pulses of lower duty cycle.

In a preferred embodiment, the detection device D further comprises a monitoring module M configured to trigger a correction or signaling action when the variable electrical resistance of one of said components C1, C2, Ci, Cn, has the high value Rd. This module M is configured to detect the change in value of the resistance of a component Ci, for example by measuring both the voltage and / or the current at the terminals of the electrical energy source.

Then the monitoring module M can trigger a cooling action, which will cause a drop in the temperature of the heat sources and of the components C1, C2, Ci, Cn. This configuration is particularly advantageous in the case of the detection devices D provided with components C1, C2, Ci, Cn, in the form of resettable fuses. Indeed, the variable resistance of this type of component finds a low value, called the holding resistance Rm, once the operating temperature has dropped, which allows the process of monitoring the temperature of the heat sources to be restarted.

In a preferred embodiment, illustrated in FIG. 2, the device D further comprises a plurality of resistors RI, R2, Ri, Rk, each having a distinct ohmic value, a resistor being connected in parallel across the terminals of each component C1, C2, Ci, Ck.

This arrangement allows the identification of a resettable fuse Ci thermally coupled to a heat source Sj, in this example a battery cell, having exceeded the first temperature threshold TS, as will be explained below. Thus, targeted cooling strategies at the heat source level can be implemented.

Such a detection device D can be configured to identify, among a plurality of heat sources S1, S2, Sj, Sn, a heat source Sj having exceeded a first predefined temperature threshold TS. The device D comprises a plurality of components Cl, C2, Ci, Ck connected in series, and each having a variable electrical resistance as a function of a respective operating temperature, the variable electrical resistance having a high value Rd, called the triggering resistance , if the operating temperature Tf j is greater than the second predefined temperature threshold, called the triggering threshold Td, and a low value Rm, called the holding resistance, otherwise.

It should be noted that according to the embodiments, the holding resistance Rm of a component Cl, C2, Ci, Ck, can correspond to a value close to 0Ω, and the tripping resistance Rd to an open circuit; this is the case for components of the fuse or switch type.

In the embodiment using resettable fuses, the holding resistor Rm has a typical resistance of 0Ω, and the trip resistor Rd has a typical resistance of a few υΩ.

In all cases, the value of the holding resistance Rm is negligible compared to the value of the triggering resistance Rd, so that Rd + (kl) * Rm ~ Rd, k being the number of components of the detection device D. The use of this feature will be explained later.

Each component Cl, C2, Ci, Ck is able to be thermally coupled to at least one of the heat sources SI, S2, Sj, Sn, so that its operating temperature is greater than or equal to the trigger threshold Td as soon as the temperature of said at least one heat source Si, Sk, Sn, is greater than or equal to the first predefined temperature threshold TS, the variable electrical resistance then having the high value Rd.

The device D further comprises a plurality of resistors

RI

R2, Ri,

Rk, having distinct ohmic values, a resistor being connected in parallel to the terminals of each component Cl, C2, Ci, Ck, so that when the electrical resistance of a component Ci has the high value

Rd, the equivalent resistance Re of the electrical chain formed by the components

Cl, C2, Ci, Ck and the resistances RI,

R2,

Ri

Rk, has a characteristic value of this component

Ci and the resistor Ri which is connected to it in parallel.

in

Alternatively, a resistor Ri can be connected parallel to a group of components Ci-1, Ci, Ci + 1, connected in series, and each coupled to at least one respective heat source. This arrangement is particularly advantageous if the heat sources are grouped. An example of application of this embodiment of the invention is the monitoring of the temperature of flexible battery cells, grouped in battery modules Ml, M2, „. Mm, as illustrated in figure 4. If one of the battery cells monitored

Sj exceeds the first predefined threshold

TS of temperature, the component Ci thermally coupled to this cell Sj will present the high resistance value Rd.

If the other battery cells do not exceed the first temperature threshold TS, all of the components connected in series will have an equivalent resistance Rd + (k-l) * Rm, k being the number of components connected in series; all of these resistors connected in parallel to resistance Ri will present an equivalent resistance

Re = Ri * [Rd + (k-1) * Rm] / [Ri + Rd + (K-1) * Rm]. The choice of components Ci, and of the resistances Ri is

done as

1) the value of the resistance Rm is negligible compared to that of Rd;

Rd + (k-l) * Rm ~ Rd.

Therefore, as

Re = Ri * [Rd + (k-1) * Rm] / [Ri + Rd + (k-1) * Rm], its value is substantially equal to

Re ~ Ri * Rd / (Ri + Rd).

2) Ri is negligible in front of Rd, so that

Ri * Rd / (Ri + Rd) ~ Ri.

Consequently, the equivalent resistance Re of a resistance Ri, connected in parallel to a component Ci thermally coupled to a battery cell Sj having exceeded the first temperature threshold TS, or to a group of components Ci-1, Ci, Ci +1, connected in series, one component Ci of which is thermally coupled to a battery cell Sj having exceeded the first temperature threshold TS, is substantially equal to Ri. By judiciously choosing distinct ohmic values for the resistances RI, R2, ... Ri, Rk, the equivalent resistance of the electric chain considered has a characteristic value of the component Ci thermally coupled to the battery cell Sj having exceeded the first threshold of temperature TS, or of the group of components Ci-1, Ci, Ci + 1, connected in series, including a component Ci thermally coupled to a battery cell Sk having exceeded the first temperature threshold TS, and of the resistance Ri which is connected in parallel.

A method of identifying a heat source Sj having exceeded a first predefined threshold TS of a temperature

T, among a plurality of heat sources

IF,

S2, Sj, Sn, will now be described with reference to the figure

The method can be implemented using a detection device as described above, that is to say comprising a plurality of components

Cl, C2, Ci, Ck may have, depending on their operating temperature, a low value, called holding resistance

Rm, or a high value called tripping resistance Rd, and a plurality of resistors RI, R2, Ri, Rk, having distinct ohmic values and connected in parallel with a component Ci or a group of components Ci-1, Ci, Ci + 1 connected in series.

The method comprises a thermal coupling step E10 of the plurality of heat sources S1, S2, Sj, Sn, with components C1, C2,

Ci, Ck, each component being thermally coupled to at least one heat source Si, so that its operating temperature is greater than or equal to the triggering threshold Td when the temperature of said at least one heat source is higher or equal to the first threshold

TS predefined temperature, the variable electrical resistance of the component then having the high value Rd, a step of connection E20 of the electrical chain formed by the components Cl, C2, Ci, Ck and the resistors RI,

R2, Ri, Rk, to a source of electrical energy E, a generation step

E30 of a supply signal U,

I by the electrical energy source E, a step E40 of detecting a response signal i, u at the terminals of the electrical energy source

E, a step of determining E50 of an equivalent resistance Re of the electric chain formed by the components Cl, C2, Ci,

Ck and the resistors RI, R2, Ri, Rk;

an identification step E60 of the component Ci whose resistance has the high value Rd, as a function of the equivalent resistance Re.

In the example illustrated, the supply signal generated in the generation step E30 is an electrical current Is, and the response signal detected in the detection step E40 is a voltage across the terminals of the current source E.

Knowing the value of the current generated Is, and the value of the voltage detected, the equivalent resistance Re of the electric chain is determined during the execution of the determination step E50. As explained above, this equivalent resistance is characteristic of the component Ci, or of the group of components, one of which has a high resistance value Rd, and of the resistance Ri which is connected to it in parallel. This allows the identification of this component Ci during the identification step E60.

Of course, the present invention is not limited to the examples and to the embodiments described and shown, but it is susceptible of numerous variants accessible to those skilled in the art.

For example, other arrangements are possible, depending on the configuration of the heat sources.

In particular, the invention is applicable to monitoring the surfaces of heat sources, by producing grids covering the surface to be monitored, and by placing components in the grids of the grid as described, thermally coupled to the surface to be monitored.

Claims (7)

1. Detection device (D) for exceeding a first predefined threshold (TS) of a temperature (T) by a heat source from a plurality of heat sources (SI, Si, Sk, Sn), the device (D) detection comprising a plurality of components (Cj) connected in series and each having a variable electrical resistance as a function of a respective operating temperature (Tfj), the variable electrical resistance having a high value (Rd) if the temperature operating temperature (Tfj) is greater than a second predefined temperature threshold, known as the release (Td), and a low value (Rm) in the case opposite, each component (Cj) being suitable at to be couple thermally at at minus one of the sources of heat ( If, Sk), so that her Operating temperature (Tfj) either higher or equal at the trigger point (Td) from when the temperature (Ti, Tk) of said at least one heat source (Si, Sk) is a predefined higher temperature, the variable electrical resistance then having the high value (Rd), the device further comprising a plurality of resistance having separate ohmic values, being connected in parallel across each component so that when the electrical resistance of a component (Ck) has the high value (Rd), the equivalent resistance (Re) of the electrical chain formed by the components separate for each resistor (Rk) connected in parallel characteristic of this component (Ck) and of the resistor (Rk) connected to it in parallel. 2. Device (D) in which the device according to the preceding claim, (D) is electrically isolated from the heat source (S). 3. Device (D) according to any one of the preceding claims, in which the at least one heat source is a battery cell. 4. Device according to any one of the preceding claims, further comprising a monitoring module (M) configured to trigger a correction or signaling action when the variable electrical resistance of one of said components (Cl, C2, Ci, Ck) has the high value (Rd). Method for identifying a heat source (Sk) having exceeded temperature (T), among a plurality of heat sources the method comprising: a thermal step of the plurality of heat sources (SI, Si, components (Cj) of a detection device (D) according to claim 1, each component being thermally coupled to at least one heat source Sk), so that its operating temperature greater than or equal to the triggering threshold (Td) when said at least one heat source (Si, Sk) is greater than or equal to the first predefined temperature threshold (TS), the variable electrical resistance of the component then having the high value (Rd), a connection step formed by the components (Cj) and electrical power source (E), - a step generation (E30) of a signal power (U, I) by the source of food electric (E), - a stage of detection (E40) of a signal Answer (i, u) at the terminals of the electric power source (E), - a step of determining (E50) an equivalent resistance (Re) of the electric chain formed by the components (Cj) and the resistors (Rj ); - an identification step (E60) of the component (Ck) whose resistance has the high value (Rd), as a function of the equivalent resistance (Re). 6. Method according to the preceding claim, wherein the source of electrical energy (E) is a current source. 7. Method according to the preceding claim, wherein the supply signal (I) is an electric current (Is) supplied in the form of periodic pulses, of fixed or variable duty cycle. 8. Vehicle (V) comprising a detection device (D) for exceeding a predefined temperature threshold (TS) according to one of claims 1 to 4.