Physical measurement at the heart of an electrochemical accumulator

Abstract

Physical Measurement at the Heart of an Electrochemical Accumulator The present invention relates to a physical measurement system (10) at the heart of an accumulator (12) having two distinct power terminals (16, 18) comprising: - an inductive sensor (20) inside said accumulator; - an assembly (22) of electrical elements external to said accumulator so as to form, with said at least one inductive sensor, a resonant circuit in a first predetermined frequency range; - a measurement module (26), external to said accumulator, configured to: - excite said resonant electrical circuit, via a frequency sweep by driving a supply voltage over a second extended predetermined frequency range including said first range; - measure at least one resonant frequency resulting from said excitation; - obtain a value of an internal physical quantity of said accumulator from said at least one measured resonant frequency.Figure for the abbreviation: Figure 1.

Description

Title of the invention: 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 inductive 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 inductive 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 separate power terminals so as to form, with said at least one inductive sensor, at least one resonant electrical circuit capable of resonating in at least a first predetermined frequency range;

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

[0016] - to excite said at least one resonant electrical circuit, via a frequency sweep by driving a supply voltage generation, at said two separate power terminals, over a second extended predetermined frequency range, said second extended predetermined frequency range comprising said at least a first predetermined frequency range;

[0017] - measure at least one resonance frequency resulting from said frequency sweep of excitement;

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

[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 inductive sensor whose inductance value varies according to the internal physical quantity to be measured, to carry out 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 an inductive 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 inductive 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 resistor and at least one capacitor so as to form in series with said at least one inductive sensor said at least one resonant electrical circuit;

[0026] - said at least one inductive sensor and each electrical element of said assembly 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 alone is maximum;

[0027] - 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;

[0028] - said filtering element assembly comprises four inserted inductive elements in series between the said two separate power terminals of said electrochemical accumulator;

[0029] - 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;

[0030] - said system comprises at least two separate inductive sensors so as to form with said set of external electrical elements of said electrochemical accumulator at least two distinct resonant electrical circuits capable of resonating in at least two first predetermined disjoint frequency ranges, said second extended predetermined frequency range comprising said at least two first predetermined frequency ranges, the at least two resulting measured resonance frequencies associated with said at least two distinct resonant electrical circuits being representative of two distinct internal physical quantities of said electrochemical accumulator;

[0031] - said at least one inductive sensor is an inductance;

[0032] - said at least one inductive sensor is at least one element belonging to the group including:

[0033] - an inductive strain gauge;

[0034] - an inductive diaphragm;

[0035] - an inductive sensor with magnetic core motion.

[0036] - said set of external electrical elements said electrochemical accumulator is disconnectable / reconnectable to said two separate power terminals

[0037] The invention also relates to a method for physical measurement at the heart of an electrochemical accumulator having two distinct power terminals, as follows:

[0038] - introduction of at least one inductive sensor inside said accumulator electrochemical, said at least one inductive sensor being connected via one of its ends to one of said two separate power terminals, the other end of said inductive sensor being connected, via a DC current blocking electrical element, to the other of said two separate power terminals;

[0039] - connection of a set of external electrical elements to said accumulator electrochemical, via each of its two ends to each of said two terminals of distinct power, so as to form, with said at least one inductive sensor, at least one resonant electrical circuit capable of resonating in at least a first predetermined frequency range;

[0040] - excitation of said at least one resonant electrical circuit, via a sweep in frequency by driving a supply voltage generation, at the level of said two separate power terminals, over a second extended predetermined frequency range, said second extended predetermined frequency range comprising said at least a first predetermined frequency range;

[0041] - measurement of at least one resonance frequency resulting from said sweep in excitation frequency;

[0042] - obtaining a value of at least one internal physical quantity of said electrochemical accumulator from said at least one measured resonance frequency

[0043] 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.

[0044] 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:

[0045] [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.

[0046] [Fig.2] [Fig.2] is a schematic representation of an example of circuit equivalent to the physical measurement system at the heart of an electrochemical accumulator, according to the present invention.

[0047] [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.

[0048] 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.

[0049] According to the present invention, the physical measurement system 10 at the heart of the electrochemical accumulator 12 further comprises at least one inductive sensor 20 suitable for being placed (i.e., introduced) inside said electrochemical accumulator 12 (i.e., inside its casing, its housing), particularly during the manufacture of said electrochemical accumulator 12, and connected via one of its one end of the inductive sensor is connected to one of the two separate power terminals, the other end of which is connected, via a DC-blocking electrical element 21, to the other of the two separate power terminals. In other words, by way of example, the electrochemical accumulator 12 is constructed directly with the inductive sensor 20 inside.

[0050] It should be noted that the introduction of such an inductive 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 inductive sensor 20 inside said electrochemical accumulator 12.

[0051] Furthermore, said measuring system 10 also includes a set 22 of electrical elements external to said electrochemical accumulator 12 (i.e. outside its casing, i.e. its housing), 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 inductive sensor 20, at least one resonant electrical circuit capable of resonating in at least a first predetermined frequency range.

[0052] As also illustrated by [Fig.1], conventionally, a load 24 is also placed in parallel with said two separate power terminals 16 and 18.

[0053] 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 first of all suitable for exciting said at least one resonant electrical circuit, via a frequency sweep by driving a supply voltage generation, at said two separate power terminals 16 and 18, over a second extended predetermined frequency range, said second extended predetermined frequency range (i.e. frequency sweep range) comprising said at least one first predetermined frequency range (i.e. resonance range).

[0054] Furthermore, the measuring module 26 is also suitable for measuring at least one resonance frequency produced by said at least one resonant electrical circuit excited by said excitation frequency sweep.

[0055] 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 measured resonance frequency. In other words, the information useful for measuring the desired internal physical quantity is studied in terms of frequency, the measured resonance frequency being representative of the associated internal physical quantity within the electrochemical accumulator 12. For example, a table determined at This preliminary step allows us to associate the measured resonance frequency value with a value of said internal physical quantity.

[0056] Thus, the measurement system 10, according to the present invention, uses the self-resonance capacity of the resonant electrical circuit formed on the one hand by said at least one inductive 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.

[0057] To do this, said at least one implemented inductive sensor 20, of said at least one resonant electrical circuit, is addressed (i.e. "queried") 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).

[0058] Thus, according to the present invention, it is proposed to use one or more inductive 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 inductive sensor, by varying its "electronic" value, that is, its inductance value as a function of the relevant internal physical quantity, 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).

[0059] The fact that the inductive sensor 20 can be interrogated remotely, 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.

[0060] 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.

[0061] Furthermore, it should be noted that the inductive nature of the sensor 20 requires the addition of a DC current blocking system against short circuits that could damage the two power terminals 16 and 18 (i.e. electrodes) of the electrochemical accumulator (i.e. of the electrochemical cell).

[0062] 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 resistor and at least one capacitor so as to form in series with said at least one inductive sensor said at least one resonant electrical circuit.

[0063] According to a first variant, said at least one inductive 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.

[0064] 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 higher than the internal impedance inherent only to said electrochemical accumulator 12 in continuous operation, then the signal of the resonator (i.e., of 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... .

[0065] 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.

[0066] 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.

[0067] 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.

[0068] According to another optional supplement, said system 10 comprises at least two separate inductive 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 in at least two first predetermined disjoint frequency ranges, said second extended predetermined frequency range comprising said at least two first predetermined frequency ranges, the at least two resulting measured resonance frequencies associated with said at least two separate resonant electrical circuits being representative of two separate internal physical quantities of said electrochemical accumulator.

[0069] 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 inductive sensors inside the electrochemical accumulator, for example one which varies the resonance frequency around 10 kHz and the other around 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 pieces of information, such as for example the temperature and the state of charge of said electrochemical accumulator.

[0070] According to another optional supplement, said at least one inductive sensor is an inductance.

[0071] In other words, this optional addition consists of using a simplified inductive sensor, corresponding to an inductor whose inductance varies with temperature. The simple inductor, or the combination of several simple inductors, when it resonates with the other external elements of the assembly 22, provides a resonant frequency whose measured value is associated with a predetermined temperature value. In other words, according to this example where the inductive sensor is a simple inductor, the measured resonant frequency value is representative of a temperature value within (i.e., at the core of) the electrochemical accumulator under consideration.

[0072] Alternatively, according to another optional supplement, said at least one inductive sensor is at least one element (or combination of elements) belonging to the group comprising:

[0073] - an inductive strain gauge;

[0074] - an inductive diaphragm;

[0075] - an inductive sensor with magnetic core motion;

[0076] - etc.

[0077] The inductive strain gauge, when it resonates with the rest of the external elements of the assembly 22, provides a resonance frequency whose measured value is associated with a predetermined value of surface strain, of stretching within (i.e. at the heart of) the electrochemical accumulator considered.

[0078] The inductive diaphragm or the inductive sensor with magnetic core movement are each capable, when they resonate with the rest of the external elements of the assembly 22, of providing a resonance frequency whose measured value is associated with a predetermined pressure value within (i.e. at the core of) the electrochemical accumulator considered.

[0079] 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.

[0080] Indeed, to validate the approach according to the present invention, simulations were carried out using an equivalent circuit.

[0081] 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.

[0082] For example, for a generic Li-ion battery cell 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 Q, R2 = 0.1 Q, R3 = 0.1 Q, R5 = 10 kQ, R6 = 1 m Q, L1 = ln H. In simulation, the behavior of a circuit composed solely of the aforementioned elements was simulated 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.

[0083] According to the present invention, the equivalent circuit 30 further specifically comprises the elements of the proposed physical measurement system, namely said at least one inductive sensor introduced inside said electrochemical accumulator and represented in the example of [Fig. 2] by the inductance L2, the value of which is, for example, suitable for varying according to the internal temperature of said electrochemical accumulator between 0.5 mH and 20 mH, said inductance L2 being further connected to the DC blocking element represented by capacitor C4, for example, with a value of 10pF, and the set of external electrical elements (i.e., components) of the corresponding electrochemical accumulator represented in the example in [Fig. 2] by resistor R8, such as, for example, R8 = 4Ω, and capacitor C5, such as, for example, C5 = 10nF. Note that according to this sizing example, where capacitor C4 (10pF) has at least one order of magnitude greater than capacitor C5 (10nF), capacitor C4 does not participate in the resonant oscillation.

[0084] With said inductance L2 inside the electrochemical accumulator, the external components R8 and C5 of said electrochemical accumulator form, once connected to the power terminals of said electrochemical accumulator, the resonator circuit whose resonance frequency is representative of the internal physical quantity to be measured at the heart of the electrochemical accumulator, such as the temperature according to this example.

[0085] Note that the simulation of an RLC circuit formed solely of the elements L2, R8, and C5 with said inductance L2 varying between 0.5mH and 20mH, presents a resonance frequency f — —1— between 11.254 KHz and 71.18 KHz respectively, these values ​​being representative of what could be expected using an inductance subjected to a temperature variation comparable to what can happen in the heart of a Li-ion cell, and allowing the reference of an ideal resonator behavior to be obtained.

[0086] 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.

[0087] It should be noted that the inductances L5, L6, L7 and L8, added as protection against disturbances due to the self-impedance of the electrochemical accumulator and / or due to externally connected devices, require sizing according to which the value of each of said inductive filtering elements L5, L6, L7 and L8 is defined such that the dynamics corresponding to the ratio of said value on said internal impedance specific only to said electrochemical accumulator is ten times lower than the initial dynamic of said electrochemical accumulator disconnected from said measuring system according to the present invention (i.e. without elements C4, C5, R8, L2, L5, L6, L7, L8 and V2).

[0088] 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.

[0089] 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, C5 and R8.

[0090] In other words, the correct sizing of the entire set of filtering elements L5, L6, L7 and L8 is defined by taking a "dynamic" point of view of the electrochemical accumulator facing a current demand, in order to take into account the need not to 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.

[0091] In simulation, the behavior of the equivalent circuit of [Fig.2] was compared to that of the resonator formed only of the elements C5, 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 L2 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 components specifically dedicated to this function, negligibly influences the frequency response of the inductive sensor L2, and the feasibility of introducing an "inductive" sensor inside the electrochemical accumulator and interrogating it by passing only through its naturally present power terminals.

[0092] In view of this behavior, it is specifically proposed according to the present invention, via the measuring module 26 of [Fig. 1], to interrogate this inductive sensor L2 with a frequency sweep, by driving the voltage generator V2 of the equivalent circuit of [Fig. 2] over a well-defined frequency range, namely a second predetermined extended frequency range comprising said at least a first predetermined frequency range in which the circuit formed by the elements C5, R8, and L2 is prone to resonance. Advantageously, the position of the resonance peak is, according to the present invention, an indicator of the temperature as in the example of [Fig.2] (or of the internal physical quantity in general for other types of inductive sensor as previously mentioned) whose measurement is required (i.e. desired).

[0093] An example of the operation of said physical measurement system 10 is now described below in relation to [Fig.3].

[0094] More specifically, according to the embodiment of the present invention illustrated by [Fig.3], the method 40 for physical measurement at the heart of an electrochemical accumulator having two separate power terminals comprises a first step 42 of introducing ICC of at least one inductive sensor inside said electrochemical accumulator, said at least one inductive sensor being connected via one of its ends to one of said two separate power terminals, the other end of said inductive sensor being connected, via an electrical DC blocking element, to the other of said two separate power terminals.

[0095] 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.

[0096] 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 inductive sensor and each electrical element of said set of external electrical elements forming, with said at least one inductive 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.

[0097] 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 inductive sensor, at least one resonant electrical circuit capable of resonating in at least a first predetermined frequency range.

[0098] The method 40 according to the present invention further comprises a step 48 of exciting said at least one resonant electrical circuit, via a sweep in frequency by driving a supply voltage generation, at said two separate power terminals, over a second extended predetermined frequency range, said second extended predetermined frequency range comprising said at least a first predetermined frequency range.

[0099] The method 40 according to the present invention also includes a measurement step 50 of at least one resonance frequency resulting from said excitation frequency sweep.

[0100] 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 resonance frequency.

[0101] 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.

[0102] The present invention thus makes it possible to provide a physical measurement of the core (i.e., the inside) of an electrochemical accumulator, via frequency scanning interrogation over a precise and significant range of frequencies, in which the information sought, namely the resonance frequency of an RLC resonator, formed by said at least one inductive sensor and a set of electrical elements external to said electrochemical accumulator, is contained, and advantageously avoids the addition of additional power dedicated to the measurement and the associated cost.

[0103] The ability to remotely query said at least one inductive sensor, 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 separate power terminals (16, 18), characterized in that said system comprises at least: - at least one inductive sensor (20) introduced inside said electrochemical accumulator, and connected via one of its ends to one of said two separate power terminals, the other end of said inductive sensor being connected, via a DC current blocking electrical element (21), to the other of said two separate 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 separate power terminals so as to form, with said at least one inductive sensor, at least one resonant electrical circuit capable of resonating in at least a first predetermined frequency range;- a measurement module (26), external to said electrochemical accumulator, configured to: - excite said at least one resonant electrical circuit, via a frequency sweep by driving a supply voltage generation, at said two separate power terminals, over a second extended predetermined frequency range, said second extended predetermined frequency range comprising said at least one first predetermined frequency range; - measure at least one resonance frequency resulting from said frequency sweep of excitation; - obtain a value of at least one internal physical quantity of said electrochemical accumulator from said at least one measured resonance frequency.

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 resistor and at least one capacitor so as to form in series with said at least one inductive sensor said at least one resonant electrical circuit.

3. A physical measurement system (10) according to claim 1 or 2, wherein said at least one inductive 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.

4. Physical measurement system (10) according to claim 1 or 2, 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 equipment connected to said electrochemical accumulator.

5. Physical measurement system (10) according to claim 4, wherein said filter element assembly (28) comprises four inductive elements inserted in series between said two separate power terminals of said electrochemical accumulator (10).

6. Physical measurement system (10) according to claim 5, 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.

7. A physical measurement system (10) according to any one of the preceding claims, wherein said system comprises at least two separate inductive 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 in at least two first predetermined disjoint frequency ranges, said second extended predetermined frequency range comprising said at least two first predetermined frequency ranges, the at least two resulting measured resonant frequencies associated with said at least two separate resonant electrical circuits being representative of two separate internal physical quantities of said electrochemical accumulator.

8. Physical measurement system (10) according to any one of the preceding claims, wherein said at least one inductive sensor is an inductance.

9. Physical measurement system (10) according to any one of the preceding claims 1 to 7, wherein said at least one inductive sensor is at least one element belonging to the group comprising: - an inductive strain gauge; - an inductive diaphragm; - an inductive sensor with magnetic core motion.

10. 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.

11. A method (40) for physical measurement within an electrochemical accumulator having two separate power terminals, comprising at least the following steps: - introduction (42) of at least one inductive sensor inside said electrochemical accumulator, said at least one inductive sensor being connected via one of its ends to one of said two separate power terminals, the other end of said inductive sensor being connected, via a DC current blocking electrical element, to the other of said two separate power terminals; - connection (46) of 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 inductive sensor, at least one resonant electrical circuit capable of resonating in at least a first predetermined frequency range;- excitation (48) of said at least one resonant electrical circuit, via a frequency sweep by driving a supply voltage generation, at said two separate power terminals, over a second extended predetermined frequency range, said second extended predetermined frequency range comprising said at least one first predetermined frequency range; - measurement (50) of at least one resonance frequency resulting from said excitation frequency sweep; - obtaining (52) a value of at least one internal physical quantity of said electrochemical accumulator from said at least one measured resonance frequency.

12. A physical measurement method (40) according to claim 11, 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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