Physical measurement process and system at the heart of an electrochemical accumulator

Abstract

Method and system for physical measurement within an electrochemical accumulator. The present invention relates to a physical measurement system (10) within an accumulator (12) having two distinct power terminals (16, 18), comprising: - a resistive sensor (20) inside said accumulator; - an assembly (22) of electrical elements external to said accumulator so as to form, with said at least one resistive sensor, a resonant circuit capable of resonating at a predetermined fixed frequency; - a measurement module (26), external to said accumulator, configured to: - excite said resonant electrical circuit by driving a supply voltage over at least one frequency range centered on said predetermined fixed frequency; - measure at least one piece of information representative of the shape of the resulting resonance peak; - obtain a value of an internal physical quantity of said accumulator from said at least one measured representative piece of information.Figure for the abbreviation: Figure 1.

Description

Title of the invention: Method and system for physical measurement at the heart of an electrochemical accumulator

[0001] The present invention relates to a physical measurement system at the heart of an electrochemical accumulator having two distinct power terminals.

[0002] The present invention also relates to a method of physical measurement at the heart of an electrochemical accumulator having two distinct power terminals.

[0003] The invention is in the field of battery management and more specifically that of electrochemical accumulators, such as Li-ion electrochemical accumulators, NiMH electrochemical accumulators, Pb electrochemical accumulators, etc.

[0004] More specifically, the present invention relates to the control of at least one internal physical quantity of an electrochemical accumulator (i.e. also called an electrochemical cell), said internal physical quantity corresponding for example to the internal temperature of the electrochemical accumulator in question, to its internal pressure, to a surface deformation, a stretching, the state of charge, the concentration of Li+ ions (i.e. Lithium+ ions), etc.

[0005] Currently, there are already solutions aimed at collecting information on the internal state of a battery corresponding to a set of electrochemical accumulators, each electrochemical accumulator having by nature two distinct power terminals (i.e. electrodes).

[0006] For example, a first solution is based on measuring the internal impedance of the electrochemical accumulator under consideration, but such a measurement requires a four-wire measurement per electrochemical accumulator, which is too costly to implement in a battery pack comprising a plurality of electrochemical accumulators.

[0007] Indeed, the addition of each of the two power terminals (i.e. electrodes) required to make a four-wire measurement, in addition to the two power terminals (i.e. electrodes) specific to the electrochemical accumulator, is a source of additional cost, because it requires not only work and / or development to ensure the sealing of the electrochemical accumulator (i.e. the electrochemical cell) around the added power terminal (i.e. the electrode), but also the deployment of connections (i.e. wires) specially dedicated to the measurement between the cell and the BMS (Battery Management System).

[0008] A second solution involves inserting optical fibers into the active part of each electrochemical accumulator, but this second solution requires requiring an expensive optical system, collimator, and spectrum analyzer to extract useful information is inconvenient. Furthermore, this instrumentation is intrusive to the architecture (i.e., the casing) of the electrochemical accumulator, leading to additional problems such as leakage management and the management of associated corrosion.

[0009] Other solutions are called "Smart Cell" type (i.e. from the English "smart cell"), namely based on the introduction of a relatively powerful microcontroller in each electrochemical accumulator (i.e. electrochemical cell), and requiring the establishment of a digital communication channel between the electrochemical accumulator in question and the outside, this communication channel being wired, capacitive, optical, by carrier current, etc., which is also complex and expensive to implement.

[0010] In other words, the existing solutions are unrealistic from a techno-economic point of view.

[0011] The aim of the invention is therefore to propose a solution allowing to minimize impact and costs of the control of at least one internal physical quantity of an electrochemical accumulator.

[0012] To this end, the invention relates to a physical measurement system at the heart of an electrochemical accumulator having two distinct power terminals, said system comprising at least:

[0013] - at least one resistive sensor introduced inside said accumulator electrochemical, and connected via one of its ends to one of said two separate power terminals, the other end of said resistive sensor being connected, via a DC current blocking electrical element, to the other of said two separate power terminals;

[0014] - a set of external electrical elements for said electrochemical accumulator, said assembly being connected via each of its two ends to each of said two distinct power terminals so as to form, with said at least one resistive sensor, at least one resonant electrical circuit capable of resonating at a predetermined fixed frequency;

[0015] - an external measuring module for the electrochemical accumulator, configured to:

[0016] - to excite said at least one resonant electrical circuit by driving a generation of supply voltage, at the level of said two separate power terminals, over at least a frequency range centered on said predetermined fixed frequency;

[0017] - measure at least one piece of information representative of the shape of the resonance peak resulting;

[0018] - obtain a value of at least one internal physical quantity of said accumulator electrochemical from said at least one representative measured information.

[0019] Thus, the present invention proposes to define a new type of sensor allowing for easy integration within electrochemical accumulators. The integration of this type of sensor is suitable for application either during the design phase of the electrochemical accumulator or at a later stage.

[0020] Advantageously, the present invention avoids adding a power terminal (i.e. electrode) to the electrochemical accumulator, apart from the positive and negative power terminals (i.e. electrodes) already present.

[0021] Thus, the present invention makes it possible, by inserting, within the electrochemical accumulator, a diagnostic tool such as the proposed resistive sensor, whose resistance value varies according to the internal physical quantity to be measured, to carry out passively, due to the passive resistive behavior similar to that of a resistor, non-destructive checks which will not disturb the proper electrochemical functioning while not modifying the arrangement of the power terminals (i.e. electrodes) of the battery elements (i.e. electrochemical accumulators) currently developed.

[0022] It should be noted that the introduction of such a resistive sensor inside the electrochemical accumulator is necessarily associated with the introduction of a DC-blocking electrical element (DCstop) to prevent direct current from flowing and to protect the two power terminals of said electrochemical accumulator against any short circuit. Such an element being, for example, a capacitor added in series with said resistive sensor inside said electrochemical accumulator.

[0023] Thus the present invention meets the need to be as close as possible to an industrial scale realization.

[0024] According to other advantageous aspects of the invention, the physical measurement system at the heart of an electrochemical accumulator comprises one or more of the following features, taken individually or in all technically possible combinations:

[0025] - said set of external electrical elements said electrochemical accumulator includes at least one inductance and at least one capacitor so as to form in series, with said at least one resistive sensor, said at least one resonant electrical circuit;

[0026] - said at least one representative piece of information belongs to the group comprising:

[0027] - an amplitude of said resulting resonance peak;

[0028] - a quality factor of said resulting resonance peak;

[0029] - said at least one resistive sensor and each electrical element of said assembly electrical elements have predetermined values ​​such that the resonant frequency of said at least one resonant electrical circuit results belongs to a third frequency range in which the internal impedance of the electrochemical accumulator alone is at its maximum;

[0030] - the system further comprises, within said electrochemical accumulator, a set of filtering elements limiting the disturbance due to the internal impedance inherent solely to said electrochemical accumulator and / or due to the presence of at least one external device connected to said electrochemical accumulator;

[0031] - said filtering element assembly comprises four inserted inductive elements in series between the said two separate power terminals of said electrochemical accumulator.

[0032] - the value of each of said inductive filtering elements is defined such that the dynamic corresponding to the ratio of said value to said internal impedance specific only to said electrochemical accumulator is ten times lower than the initial dynamic of said electrochemical accumulator disconnected from said system;

[0033] - said system comprises at least two separate resistive sensors so as to to form with said set of external electrical elements said electrochemical accumulator at least two distinct resonant electrical circuits capable of resonating at at least two distinct predetermined fixed frequencies, said measuring module, external to said electrochemical accumulator, being configured to:

[0034] - to excite said at least one resonant electrical circuit by driving a generation of supply voltage, at the level of said two separate power terminals, over at least two separate frequency ranges centered respectively on said at least two separate predetermined fixed frequencies;

[0035] - measure information representative of the shape of each resonance peak resulting;

[0036] - obtain a value of at least one internal physical quantity of said accumulator electrochemical from each representative measured information;

[0037] - each excitation frequency range is narrow and defined at -3 dB of amplitude of the resonance peak associated with each predetermined fixed frequency;

[0038] - said at least one resistive sensor is at least one element belonging to the group including at least:

[0039] - an assembly comprising at least one NTC-type resistor with a coefficient of negative temperature;

[0040] - an assembly comprising at least one CTP-type resistor with a coefficient of positive temperature;

[0041] - a strain gauge;

[0042] - a resistive pressure sensor;

[0043] - said set of external electrical elements said electrochemical accumulator is disconnectable / reconnectable to said two separate power terminals.

[0044] The invention also relates to a method for physical measurement at the heart of an electrochemical accumulator having two distinct power terminals, comprising at least the following steps:

[0045] - introduction of at least one resistive sensor inside said accumulator electrochemical, said at least one resistive sensor being connected via one of its ends to one of said two separate power terminals, the other end of said resistive sensor being connected, via a DC current blocking electrical element, to the other of said two separate power terminals;

[0046] - connection of a set of external electrical elements to said accumulator electrochemical, via each of its two ends to each of said two distinct power terminals, so as to form, with said at least one resistive sensor, at least one resonant electrical circuit capable of resonating at a predetermined fixed frequency;

[0047] - excitation of said at least one resonant electrical circuit by driving a generation supply voltage, at the level of said two separate power terminals, over at least a frequency range centered on said predetermined fixed frequency;

[0048] - measurement of at least one piece of information representative of the shape of the resonance peak resulting;

[0049] - obtaining a value of at least one internal physical quantity of said electrochemical accumulator from said at least one representative measured information.

[0050] According to another advantageous aspect of the invention, the method of physical measurement at the heart of an electrochemical accumulator further comprises the introduction inside said electrochemical accumulator, of a set of filtering elements limiting the disturbance due to the internal impedance specific only to said electrochemical accumulator and / or due to the presence of at least one external equipment connected to said electrochemical accumulator.

[0051] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0052] [Fig-1] [Fig.1] is a schematic representation of a measurement system physics at the heart of an electrochemical accumulator according to the present invention.

[0053] [Fig.2] [Fig.2] is a schematic representation of an example of a circuit equivalent to the physical measurement system at the heart of an electrochemical accumulator, according to the present invention.

[0054] [Fig.3] [Fig.3] is a flowchart of the main steps of a physical measurement process at the heart of an electrochemical accumulator according to the present invention.

[0055] Fig. 1 illustrates an embodiment of a physical measurement system 10 at the heart of an electrochemical accumulator 12. In Fig. 1, said electrochemical accumulator 12 comprises, in its casing, an active part 14 and has two distinct power terminals (i.e. two distinct electrodes) 16 and 18.

[0056] According to the present invention, the physical measurement system 10 at the heart of the electrochemical accumulator 12 further comprises at least one resistive sensor 20 suitable for being placed (i.e., inserted) inside said electrochemical accumulator 12 (i.e., inside its casing), particularly during the manufacture of said electrochemical accumulator 12, and connected via one of its ends to one of said two separate power terminals, the other end of said resistive sensor being connected, via a DC-blocking electrical element 21, to the other of said two separate power terminals. In other words, according to one example, the electrochemical accumulator 12 is built directly with the resistive sensor 20 inside.

[0057] It should be noted that the introduction of such a resistive sensor 20 inside the electrochemical accumulator is necessarily associated with the introduction of the DC-blocking electrical element 21 (from the English "DCstop") to prevent direct current from flowing and to protect the two power terminals of said electrochemical accumulator against any short circuit. Such an element 21 being, for example, a capacitor added in series with said resistive sensor 20 inside said electrochemical accumulator 12.

[0058] Furthermore, said measuring system 10 also includes a set 22 of electrical elements external to said electrochemical accumulator 12 (i.e. outside its envelope, i.e. its casing), said set 22 being connected, in parallel as illustrated by [Fig. 1], via each of its two ends to each of said two separate power terminals 16 and 18 so as to form, with said at least one resistive sensor 20, at least one resonant electrical circuit capable of resonating at a predetermined fixed frequency.

[0059] As also illustrated by [Fig.1], conventionally, a load 24 is also placed in parallel with said two separate power terminals 16 and 18.

[0060] The measuring system 10 further comprises, according to the present invention, a measuring module 26, external to said electrochemical accumulator. Such a measuring module 26 is firstly adapted to excite said at least one resonant electrical circuit, by driving a supply voltage generation, at said two separate power terminals 16 and 18, over at least a frequency range centered on said predetermined fixed frequency.

[0061] In addition, the measuring module 26 is also suitable for measuring at least one piece of information representative of the shape of the resulting resonance peak.

[0062] The measuring module 26 is further adapted to obtain a value of at least one internal physical quantity of said electrochemical accumulator 12 from said at least one representative measured information. In other words, the information useful for measuring the desired internal physical quantity is studied in terms of frequency, the measured resonant frequency being representative of the associated internal physical quantity within the electrochemical accumulator 12. For example, a predetermined table makes it possible to associate the measured resonant frequency value with a value of said internal physical quantity.

[0063] Thus, the measurement system 10, according to the present invention, uses the self-resonance capacity of said at least one resonant electrical circuit formed on the one hand by said at least one resistive sensor 20 internal to the electrochemical accumulator 12 and on the other hand by a set 22 of electrical elements external to said electrochemical accumulator 12.

[0064] To do this, said at least one implemented resistive sensor 20, of said at least one resonant electrical circuit, is addressed (i.e. "polled") in frequency via said measuring module 26 and not in direct current, and is only connected between the two power terminals 16 and 18 (i.e. power electrodes), respectively positive and negative, naturally present to connect the electrochemical accumulator 12 (i.e. of the electrochemical cell), thus avoiding any additional power terminal (i.e. additional electrode).

[0065] Thus, according to the present invention, it is proposed to use one or more resistive sensors inside the electrochemical accumulator (i.e., the electrochemical cell), the useful information from which is studied in terms of frequency, and forming part of a resonant circuit whose remaining components are located outside the cell, even at a considerable distance, such as, for example, on the printed circuit board (i.e., the PCB) of the battery management system (BMS) of the battery module. Said at least one resistive sensor, by varying its "electronic" value, that is, its resistance value according to the internal physical quantity involved, in particular the temperature of its environment, is thus able to provide information on what is happening inside the electrochemical accumulator (i.e., the electrochemical cell).

[0066] The fact that it is possible to remotely query the resistive sensor 20, and without additional connections, constitutes a considerable advantage from the point of view of possible industrialization, because it leaves the manufacturer free to choose the location of the resonant circuit (i.e. in particular of these external elements) according to what is most advantageous for him.

[0067] As an optional addition, said at least one representative piece of information belongs to the group comprising:

[0068] - an amplitude of said resulting resonance peak;

[0069] - a quality factor of said resulting resonance peak.

[0070] As an optional complement, said set 22 of external electrical elements of said electrochemical accumulator is disconnectable / reconnectable to said two separate power terminals 16 and 18. In other words, according to this optional complement, it is also possible to implement only a single resonant circuit, the connection of which to the different elements of the battery, namely the different electrochemical accumulators of the battery, is routed by multiplexing.

[0071] In addition, it should be noted that the resistive nature of the sensor 20 requires the addition of a direct current blocking system against short circuits which could damage the two power terminals 16 and 18 (i.e. electrodes) of the electrochemical accumulator (i.e. of the electrochemical cell).

[0072] As an optional complement, as illustrated later by [Fig.2], said set 22 of external electrical elements of said electrochemical accumulator 12 includes at least one inductor and at least one capacitor so as to form in series, with said at least one resistive sensor, said at least one resonant electrical circuit.

[0073] According to a first variant, said at least one resistive sensor 20 and each electrical element of said set 22 of electrical elements have predetermined values ​​such that the resonance frequency of said at least one resulting resonant electrical circuit belongs to a third frequency range in which the internal impedance of said electrochemical accumulator 12 alone is maximum.

[0074] Such a first variant is interesting because if the resulting impedance of said electrochemical accumulator 12 (i.e., the overall impedance of the electrochemical accumulator after connection to elements 20 and 22 of the present invention) is high in a specific frequency range, and several orders of magnitude greater than the internal impedance inherent only to said electrochemical accumulator 12 in DC operation, then the signal from the resonator (i.e., the resonant circuit) is likely to be only slightly attenuated by the internal impedance inherent only to said electrochemical accumulator 12 (i.e.,the natural impedance of the electrochemical cell 12 without connection to elements 20 and 22 of the present invention), and remains permanently usable, without requiring the addition of dedicated filtering elements to protect the useful signal of the resonator from disturbance due to the natural impedance of the electrochemical accumulator itself and / or due to the possible presence of external equipment connected to the electrochemical accumulator, such as a motor, a charger, etc... .

[0075] As an alternative to the first variant, according to a second variant, as illustrated in dotted lines on [Fig.1] and shown in detail on [Fig.2] described below, the physical measurement system 10 according to the present invention further includes optionally, inside said electrochemical accumulator 12, a set 28 of filtering elements limiting the disturbance due to the internal impedance specific only to said electrochemical accumulator and / or due to the presence of at least one external equipment connected to said electrochemical accumulator 12.

[0076] As an optional complement to this second variant, as illustrated later by [Fig.2], said set 28 of filtering elements comprises four inductive elements inserted in series between said two separate power terminals 16 and 18 of said electrochemical accumulator 12.

[0077] As an option for this optional complement, the value of each of said inductive filtering elements is defined such that the dynamics corresponding to the ratio of said value to said internal impedance specific only to said electrochemical accumulator is ten times lower than the initial dynamics of said electrochemical accumulator disconnected from said system.

[0078] According to another optional addition, said system 10 comprises at least two separate resistive sensors so as to form with said set of external electrical elements of said electrochemical accumulator at least two separate resonant electrical circuits capable of resonating at at least two distinct predetermined fixed frequencies, said measuring module, external to said electrochemical accumulator, being configured to:

[0079] - to excite said at least one resonant electrical circuit by driving a generation of supply voltage, at the level of said two separate power terminals, over at least two separate frequency ranges centered respectively on said at least two separate predetermined fixed frequencies;

[0080] - to measure information representative of the shape of each resonance peak resulting;

[0081] - obtain a value of at least one internal physical quantity of said accumulator electrochemical analysis based on each representative measured piece of information.

[0082] Indeed, knowing that an electronic object can have several resonance frequencies, with a clever choice of sensors / components, according to this optional complement it is proposed to introduce several different resistive sensors inside the electrochemical accumulator, for example one which has a fixed resonance frequency of 10 kHz and the other at 100 kHz, making it possible to discern the origin (i.e. of the internal physical quantity) associated with the measured signal and thus to obtain two distinct internal physical quantities, such as for example the temperature and the state of charge of said electrochemical accumulator.

[0083] As an optional complement, each excitation frequency range is narrow and defined at -3 dB of the amplitude of the resonance peak associated with each predetermined fixed frequency.

[0084] According to another optional supplement, said at least one resistive sensor is at least one element belonging to the group comprising at least:

[0085] - an assembly comprising at least one NTC-type resistor with a coefficient of negative temperature;

[0086] - an assembly comprising at least one CTP-type resistor with a coefficient of positive temperature;

[0087] - a strain gauge;

[0088] - a resistive pressure sensor.

[0089] A simple NTC type resistor (or a combination of NTC type resistors) or a simple PTC type resistor (or a combination of PTC type resistors) is capable, when it resonates with the rest of the external elements of the assembly 22, of providing a resonance peak whose shape in amplitude or in quality factor is associated with a predetermined temperature value.

[0090] In particular, a simple NTC type resistor (also called a thermistor) is a component whose resistance increases as its temperature decreases. It should be noted that many components of this type are commercially available, such as, for example, the Vishay© NTCLE203E3104GB0 NTC type resistor, with very different nominal resistance values ​​at 25 °C, so that each choice of resistive sensor consequently requires a redesign of the other constituent elements of the measurement system according to the present invention.

[0091] The resistive strain gauge, when it resonates with the rest of the external elements of the assembly 22, provides a resonance peak whose shape in amplitude or quality factor is associated with a predetermined value of surface strain, of stretching within (i.e. at the heart of) the electrochemical accumulator considered.

[0092] The resistive pressure sensor, when it enters into resonance with the rest of the external elements of the assembly 22, is capable of providing a resonance peak whose shape in amplitude or quality factor is associated with a predetermined pressure value within (i.e. at the heart of) the electrochemical accumulator considered.

[0093] Fig. 2 is a schematic representation of an example of an equivalent circuit 30 to the physical measurement system at the heart of an electrochemical accumulator, according to the present invention.

[0094] Indeed, to validate the approach according to the present invention, simulations were carried out using an equivalent circuit.

[0095] According to the example of [Fig.2], the electrochemical accumulator corresponds in particular to a generic Li-ion cell represented by a circuit according to an "RC model" of a battery having a capacity of 3 to 5 Ampere-hours (i.e. 3.5 to 5Ah), composed of the capacitive elements: Cl, C2, C3, resistive elements: RI, R2, R3, R5, R6, inductive elements: L1 and the current or voltage generators Bl, B2 and II.

[0096] For example, for a generic Li-ion cell in a battery with a capacity of 3 to 5 Ampere-hours, the following values ​​are considered: C1 = 1000 pF, C2 = 10 pF, C3 = 18000 F, R1 = 0.1 Ω, R2 = 0.1 Ω, R3 = 0.1 Ω, R5 = 10 kΩ, R6 = lmΩ, L1 = lnH. In simulation, the behavior of a circuit composed solely of the aforementioned elements was tested to verify that its behavior is consistent, in particular, with that of an electrochemical accumulator with a capacity of approximately 3.5 Ah that discharges with a constant current of one ampere. It should be noted that the aforementioned values ​​are indicative and not restrictive, as they are used in simulation without necessarily having a direct physical counterpart.

[0097] According to the present invention, the equivalent circuit 30 further specifically comprises the elements of the proposed physical measurement system, namely said at least resistive sensor introduced inside said electrochemical accumulator and represented in the example of [Fig.2] by the resistance R8, said resistance R8 being further connected to the DC current blocking electrical element represented by the capacitor C5 for example of value equal to IpF, and the set of external electrical elements (i.e. components) of said corresponding electrochemical accumulator represented in the example of [Fig.2] by the inductance L2, such as for example L2=10pH, and the capacitor C4, such as for example C4=3.185pF.

[0098] With said resistance R8 inside the electrochemical accumulator, the external components L2 and C4 of said electrochemical accumulator form, once connected to the power terminals of said electrochemical accumulator, the resonator circuit whose information representing the shape of the resonance peak is representative of the internal physical quantity to be measured at the heart of the electrochemical accumulator.

[0099] It should be noted that the simulation of such an equivalent circuit 30 with said resistance R8 varying between 1 and 100Ω in steps of 10Ω (these values ​​being representative of what could be expected using a resistance subjected to a temperature variation comparable to what can occur in the heart of a Li-ion cell), exhibits a resonance frequency f — —1— of 28.2 kHz, stable regardless of the value J 0 2nyLC of the resistance, but that depending on the resistance value, it is the shape of the resonance peak that varies in amplitude or in quality factor Q such that n _ J, / Z”., and v - r\c According to the present invention, this shape is used as an indicator of the size internal physical properties to be measured, such as temperature, for a simple resistance of type NTC or PTC.

[0100] Note that the higher the value of the quality factor Q, the narrower the frequency band used for the excitation of the RLC circuit, and in particular defined at -3 dB of the peak amplitude (in other words: the larger Q is, the more the peak is accentuated).

[0101] The example in [Fig. 2] corresponds in particular to the second variant mentioned above, where the physical measurement system according to the present invention further optionally comprises, within said electrochemical accumulator, a set of filtering elements limiting the disturbance due to the internal impedance inherent solely to said electrochemical accumulator and / or due to the presence of at least one external device connected to said electrochemical accumulator. This set of filtering elements, referenced 28 in [Fig. 1], corresponds in the equivalent circuit 30 of [Fig. 2] to the inductances L5, L6, L7, and L8 in series with the separate power terminals of the electrochemical accumulator and is intended to eliminate a disturbance that approximates a direct current. According to the example in [Fig. 2], the value of these four inductances is, for example, 100 mH.

[0102] Note that the inductances L5, L6, L7 and L8 added as protection to avoid disturbances due to the self-impedance of the electrochemical accumulator and / or due to what is connected to it externally require a dimensioning according to which the value of each of said inductive filtering elements L5, L6, L7 and L8 is defined such that the dynamic corresponding to the ratio of said value to said self-impedance of said electrochemical accumulator alone is ten times less than the initial dynamic of said electrochemical accumulator disconnected from said measurement system according to the present invention (i.e. without elements C4, C5, R8, L2, L5, L6, L7, L8 and V2).

[0103] Note that the definition of "initial dynamics" depends on the application. For example, a sudden acceleration of an electric vehicle requires a large current in a few tens of milliseconds, whereas a battery recharge only requires slow profiles.

[0104] Such sizing amounts, in practice, to seeking a current rise time in the electrochemical accumulator that is at most ten times greater than the initial time when said electrochemical accumulator is disconnected from said measuring system according to the present invention (i.e. without elements C4, C5, R8, L2, L5, L6, L7, L8 and V2), considering that "initial time" means the time that the current would have taken to establish itself in the absence of elements L2, C4 and R8.

[0105] In other words, the correct sizing of the entire set of filtering elements L5, L6, L7 and L8 is defined by adopting a "dynamic" point of view of the electrochemical accumulator facing a current demand, in order to take into account takes into account the need to not degrade the electrical specifications of the electrochemical accumulator (i.e. of the electrochemical cell), namely to allow the current which enters or leaves the electrochemical accumulator to pass through the power circuit.

[0106] In simulation, the behavior of the equivalent circuit of [Fig.2] was compared to that of the resonator formed only of the elements C4, R8, and L2, and it was observed that there is no substantial difference and that the frequency position of the resonance peak is representative of the value of the sensor R8 placed inside the cell, with an acceptable shift (i.e. whose value is less than a predetermined threshold) towards the high frequencies.More specifically, such an acceptable shift towards higher frequencies means that the impedance of the electrochemical accumulator corresponding to a generic Li-ion cell, properly isolated by the components specifically dedicated to this function, negligibly influences the frequency response of the resistive sensor R8, and the feasibility of introducing a "resistive" sensor inside the electrochemical accumulator and querying it at a fixed frequency or using a narrow excitation frequency range, centered on said predetermined fixed frequency, and defined at -3 dB of the amplitude of the resonance peak associated with said predetermined fixed frequency, and this by passing only through its naturally present power terminals.

[0107] In view of this behavior, it is specifically proposed according to the present invention, via the measurement module 26 of [Fig. 1], to interrogate this resistive sensor R8 at a fixed frequency or using a narrow excitation frequency range, centered on said predetermined fixed frequency and defined at -3 dB of the amplitude of the resonance peak associated with said predetermined fixed frequency, by driving the voltage generator V2 of the equivalent circuit of [Fig. 2] at a fixed frequency or using a narrow excitation frequency range, centered on said predetermined fixed frequency and defined at -3 dB of the amplitude of the resonance peak associated with said predetermined fixed frequency. Advantageously, the shape of the resonance peak, in amplitude or in quality factor Q, is, according to the present invention, an indicator of the temperature as in the example of [Fig. 1].2] (or the internal physical quantity in general for other types of resistive sensors as mentioned above) whose measurement is required (i.e. desired).

[0108] An example of the operation of said physical measurement system 10 is now described below in relation to [Fig.3].

[0109] More specifically, according to the embodiment of the present invention illustrated in [Fig. 3], the method 40 for physical measurement within an electrochemical accumulator having two distinct power terminals comprises a first step 42 of introducing ICC at least one resistive sensor inside said electrochemical accumulator, said at least one resistive sensor being connected via one of its ends to one of said two separate power terminals, the other end of said resistive sensor being connected, via a DC current blocking electrical element, to the other of said two separate power terminals.

[0110] Optionally, as shown in dotted lines, particularly when the second variant mentioned above is implemented, the method 40 according to the present invention further comprises a step 44 of introducing IEF into said electrochemical accumulator, a set of filtering elements limiting the disturbance due to the internal impedance specific only to said electrochemical accumulator and / or due to the presence of at least one external equipment connected to said electrochemical accumulator.

[0111] Note that this optional step 44 is not implemented (i.e. does not need to be implemented) when, as described above, according to a first variant, said at least one resistive sensor and each electrical element of said set of external electrical elements forming, with said at least one resistive sensor, at least one resonant electrical circuit, have predetermined values ​​such that the resonance frequency of said at least one resulting resonant electrical circuit belongs to a third frequency range in which the internal impedance of said electrochemical accumulator alone is maximum.

[0112] With or without the aforementioned option 44, the method 40 according to the present invention also includes a step 46 of connecting said set of external electrical elements to said electrochemical accumulator, via each of its two ends to each of said two separate power terminals, so as to form, with said at least one resistive sensor, at least one resonant electrical circuit capable of resonating at a predetermined fixed frequency.

[0113] The method 40 according to the present invention further comprises an excitation step 48 of said at least one resonant electrical circuit by driving a supply voltage generation, at said two separate power terminals, over at least a frequency range centered on said predetermined fixed frequency.

[0114] The method 40 according to the present invention also includes a measurement step 50 M of at least one information representative of the shape of the resulting resonance peak.

[0115] The method 40 according to the present invention finally includes a step 52 of obtaining OBT of a value of at least one internal physical quantity of said electrochemical accumulator from said at least one measured representative information.

[0116] A person skilled in the art will understand that the invention is not limited to the embodiments described, nor to the particular examples of the description, the embodiments and variants mentioned above being capable of being combined with each other to generate new embodiments of the invention.

[0117] The present invention thus makes it possible to provide a physical measurement of the core (i.e., the inside) of an electrochemical accumulator, via the fixed-frequency interrogation of an RLC resonator formed by said at least one internal resistive sensor of said electrochemical accumulator and a set of external electrical elements of said electrochemical accumulator, or by using a narrow excitation frequency range, centered on said predetermined fixed frequency of the RLC resonator and defined at -3 dB of the amplitude of the resonance peak associated with said predetermined fixed frequency, and advantageously avoids the addition of additional power terminal(s) dedicated to the measurement and the associated cost.

[0118] The ability to remotely query said at least one resistive sensor which has a passive behavior, and without additional connections, constitutes a considerable advantage from the point of view of possible industrialization, because it leaves the manufacturer free to choose the location of the resonant circuit according to what is most advantageous for him.

Claims

Demands

1. A physical measurement system (10) at the heart of an electrochemical accumulator (12) having two distinct power terminals (16, 18), characterized in that said system comprises at least: - at least one resistive sensor (20) introduced inside said electrochemical accumulator, and connected via one of its ends to one of said two distinct power terminals, the other end of said resistive sensor being connected, via a DC current blocking electrical element (21), to the other of said two distinct power terminals; - an assembly (22) of electrical elements external to said electrochemical accumulator, said assembly being connected via each of its two ends to each of said two distinct power terminals so as to form, with said at least one resistive sensor (20), at least one resonant electrical circuit capable of resonating at a predetermined fixed frequency;- a measurement module (26), external to said electrochemical accumulator, configured to: - excite said at least one resonant electrical circuit by driving a supply voltage generation, at said two separate power terminals, over at least one frequency range centered on said predetermined fixed frequency; - measure at least one representative piece of information of the shape of the resulting resonance peak; - obtain a value of at least one internal physical quantity of said electrochemical accumulator from said at least one representative piece of information measured.

2. Physical measurement system (10) according to claim 1, wherein said set (22) of external electrical elements to said electrochemical accumulator (12) comprises at least one inductor and at least one capacitor so as to form in series with said at least one resistive sensor said at least one resonant electrical circuit.

3. Physical measurement system (10) according to claim 1 or 2, wherein said at least one representative information belongs to the group comprising: - an amplitude of said resulting resonance peak; - a quality factor of said resulting resonance peak.

4. Physical measurement system (10) according to any one of the preceding claims, wherein said at least one resistive sensor (20) and each electrical element of said set (22) of electrical elements have predetermined values ​​such that the resonant frequency of said at least one resulting resonant electrical circuit belongs to a third frequency range in which the internal impedance of said electrochemical accumulator (12) alone is maximum.

5. Physical measurement system (10) according to any one of the preceding claims 1 to 3, further comprising, within said electrochemical accumulator (12), a set (28) of filtering elements limiting the disturbance due to the internal impedance inherent only in said electrochemical accumulator and / or due to the presence of at least one external piece of equipment connected to said electrochemical accumulator (12).

6. Physical measurement system (10) according to claim 5, wherein said filter element assembly (28) comprises four inductive elements inserted in series between said two separate power terminals of said electrochemical accumulator.

7. Physical measurement system (10) according to claim 6, wherein the value of each of said inductive filtering elements is defined such that the dynamics corresponding to the ratio of said value to said internal impedance specific only to said electrochemical accumulator is ten times lower than the initial dynamics of said electrochemical accumulator disconnected from said system.

8. A physical measurement system (10) according to any one of the preceding claims, wherein said system (10) comprises at least two separate resistive sensors such as to form, with said set of external electrical elements of said electrochemical accumulator, at least two separate resonant electrical circuits capable of resonating at at least two distinct predetermined fixed frequencies, said measurement module, external to said electrochemical accumulator, being configured to: - excite said at least one resonant electrical circuit by driving a supply voltage generation, at said two separate power terminals, over at least two frequency ranges distinct, centered respectively on said at least two distinct predetermined fixed frequencies; - measure information representative of the shape of each resulting resonance peak; - obtain a value of at least one internal physical quantity of said electrochemical accumulator from each representative information measured.

9. Physical measurement system (10) according to any one of the preceding claims, wherein each excitation frequency range is narrow and defined at -3 dB of the amplitude of the resonance peak associated with each predetermined fixed frequency.

10. Physical measurement system (10) according to any one of the preceding claims 1 to 9, wherein said at least one resistive sensor (20) is at least one element belonging to the group comprising at least: - an assembly comprising at least one NTC type resistor with a negative temperature coefficient; - an assembly comprising at least one PTC type resistor with a positive temperature coefficient; - a strain gauge; - a resistive pressure sensor.

11. Physical measurement system (10) according to any one of the preceding claims, wherein said set of external electrical elements to said electrochemical accumulator is disconnectable / reconnectable to said two separate power terminals.

12. A method (40) for physical measurement within an electrochemical accumulator having two separate power terminals, comprising at least the following steps: - introducing (42) at least one resistive sensor into said electrochemical accumulator, said at least one resistive sensor being connected via one of its ends to one of said two separate power terminals, the other end of said resistive sensor being connected, via a DC-blocking electrical element, to the other of said two separate power terminals; - connecting (46) a set of external electrical elements to said electrochemical accumulator, via each of its two ends to each of said two separate power terminals, so as to form, with said at least one resistive sensor, at least one resonant electrical circuit capable of resonating at a predetermined fixed frequency; - excitation (48) of said at least one resonant electrical circuit by driving a supply voltage generation, at said two separate power terminals, over at least one frequency range centered on said predetermined fixed frequency; - measurement (50) of at least one information representative of the shape of the resulting resonance peak; - obtaining (52) a value of at least one internal physical quantity of said electrochemical accumulator from said at least one measured representative information.

13. A method (40) of physical measurement according to claim 12, further comprising the introduction (44) inside said electrochemical accumulator, of a set of filtering elements limiting the disturbance due to the internal impedance specific only to said electrochemical accumulator and / or due to the presence of at least one external equipment connected to said electrochemical accumulator.

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