Battery management system

Abstract

The present invention relates to a battery management system (BMS) for a battery, which can be composed of a single element or a plurality of single elements, which can be arranged in modular assemblies, connected in series or in parallel, and by electromagnetic or electronic disconnection means connecting, on one hand, at least one electrode of the electric core and, on the other hand, the terminals of the same polarity of the modular assembly or of the battery, the BMS comprising at least one single device for detecting deep discharge, overcurrent discharge and short circuit discharge by measuring the voltage at the terminals of the battery.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of lithium batteries for accumulators, and more particularly to the fixing of said batteries. BACKGROUND

[0002] An accumulator is composed of electrochemical elements, which can be connected in series or in parallel, to obtain the required voltage and current.

[0003] Existing batteries, such as but not limited to those used in the aeronautical field, use lead or nickel-cadmium, have a high mass, a short life and a high self-discharge, and require regular maintenance. However, due to their low energy density, they are almost free of risks of overheating and fire. Usually, a fuse or a circuit breaker is sufficient to provide short-circuit protection.

[0004] In the event of a short circuit or overcurrent, the battery must be disconnected to avoid damaging the battery and to avoid overheating the battery or its connecting cables.

[0005] Lithium batteries also require overcurrent and short-circuit protection circuits. An electromechanical circuit breaker or a fuse is usually used, or an electronic circuit that measures the current and controls a switching device. However, measuring the current is not simple.

[0006] Several current measurement methods exist (shunt, magnetic measurement or by thermal effect). However, these methods can be relatively energy-consuming, which can require the use of a "standby" mode and an "active" mode. In addition, this is hardly compatible with short-circuit protection, which can occur at any time.

[0007] In addition, thermal starter batteries must provide very high currents in a few seconds to a few tens of seconds. The current of the circuit breaker (switching device) must therefore be set to a fairly high value, of the order of half the short-circuit current (at half the open-circuit voltage, the maximum power provided by the battery is reached, and the current is half the short-circuit current). With the appearance of aging problems or in low-temperature conditions, the internal resistance of the battery increases, and therefore the short-circuit current decreases. This current can be lower than the tripping current. In this case, this protection will no longer work. The use in these conditions can lead to a complete discharge of the internal resistance of the battery, causing overheating and then fire.

[0008] Finally, for example but not limited to, a 17 Ah non-modular battery can provide a short-circuit current of more than 2000 A. The cut-off device that guarantees the disconnection of the battery from its utilization circuit must therefore be able to withstand this current. Semiconductors capable of withstanding this current are not common, in fact, several components of lower current are connected in parallel. Current equalization is difficult to achieve, which requires the use of components of super-size. Measuring a 2000 A current also poses the problem of having to choose between accuracy and static consumption. SUMMARY

[0009] The present invention aims to overcome certain drawbacks of the prior art by proposing a method for detecting abnormal situations and a lithium battery management system that is simple, reliable and easily adaptable to different intensities and voltages of individual or modular elements.

[0010] One object of the invention is to enable the method to detect deep discharge, short-circuit discharge and overcurrent discharge conditions of a lithium battery without passing through current measurements.

[0011] This object is achieved by a method for detecting abnormal operating conditions (deep discharge, overcurrent discharge and short-circuit discharge) of an individual battery element or of a plurality of individual elements, comprising the following steps:

[0012] Sampling at least one voltage proportional to the voltage at the terminals of an individual element or of a group of individual elements at the common point of a voltage divider bridge having at least two resistors;

[0013] Comparing the detected voltage with a reference threshold;

[0014] The comparison with the reference threshold triggers the implementation of the following:

[0015] An evolution evaluation assessed by integration, analog or digital means;

[0016] Comparing this evaluation with a detection voltage threshold Td, according to which the individual element or the group of monitored individual elements is at least disconnected from the battery terminals.

[0017] According to another feature, the step of digital integration evaluation comprises:

[0018] A step of calculating the evolution slope (P) of the voltage curve by using at least two measurements

[0019] At least one step of comparing the calculated slope with a stored "RapidThreshold" value, i.e. if the slope exceeds the "RapidThreshold" value, a weighting factor is applied that increases the integration evolution acceleration so that it crosses the triggering voltage threshold Td more quickly, or if it does not exceed, a weighting factor is applied that has no acceleration effect.

[0020] Another object is to enable the management system to monitor deep discharge, short-circuit discharge and overcurrent discharge conditions of a lithium battery without passing through current measurements.

[0021] This aim is achieved by a battery management system (BMS) for a battery, which can be made up of a single element or a plurality of single elements, which can be arranged in modular assemblies and connected in series, in parallel or in a plurality of parallel associations of a plurality of series modular assemblies, forming the battery; said system comprises means suitable for performing the steps of the detection method according to the present application.

[0022] According to another characteristic, the battery management system (BMS) comprises at least:

[0023] a voltage divider bridge with at least two resistors for sampling a voltage proportional to the voltage at the terminals of at least one single element or group of single elements of the battery,

[0024] a detection device for detecting abnormal conditions,

[0025] a disconnection device,

[0026] said detection device communicates with said disconnection device to activate it in the event of detection of an abnormal condition, said disconnection device being connectable to the battery and comprising at least two MOSFETs.

[0027] Another aim is to propose a digital solution for the detection device.

[0028] This aim is achieved by a battery management system (BMS) for a battery according to the present application, comprising a microprocessor equipped with at least one memory which allows the storage of at least one "Refintegration" threshold variable and of a stored detection voltage value Td, said memory also containing a program executed by the microprocessor which allows the collection of voltage curve points, comparison and decision, the implementation of an equation which allows integration, said microprocessor receiving the voltage V global as input, storing the measured values according to the determined frequency to observe the voltage curve V global and comparing the value of the voltage curve V global with the "Refintegration" value, then when a "Refintegration" threshold crossing is detected, said threshold being defined by a value stored in the memory, triggering the integration calculation of the curve V global and comparing the value of the calculated integration curve (V integ ) with the stored detection voltage value Td to activate the disconnection device to implement the shutdown.

[0029] According to another characteristic, the memory of the microprocessor also comprises the value of the stored "RapidThreshold" variable, so as to compare the voltage V globalthe variation dV of the voltage curve V is compared with the "RapidThreshold" to determine the calculation of the voltage curve V global the integral of the voltage curve V

[0030] According to another characteristic, the calculation of the integral comprises the consideration of a "slope and / or ordinate" variable, wherein the microprocessor calculates the "slope and / or ordinate" variable from the recorded voltage curve V global The data are calculated to obtain the "slope and / or ordinate" variable.

[0031] Another object is to propose an analog solution for the detection device.

[0032] This object is achieved by a battery management system (BMS) for a battery according to the present application, comprising at least one comparator U1; a voltage divider bridge (R1, R2 or R9, R4) installed between the terminals of a modular assembly of the battery or of a single element of the battery, with the common point of the resistors connected to the input of the negative terminal of the comparator U1 to provide a voltage value proportional to the voltage value V1 at the terminals of the battery at the ratio defined by the values of the two resistors (R1, R2 or R9, R4) and the positive terminal of the comparator is connected to a diode or to a power supply unit to define a reference voltage V2.

[0033] Thus, by varying the resistance and the reference voltage value, the system will be able to adapt to batteries comprising different voltage and current characteristics.

[0034] According to another characteristic, the integrator assembly comprises a resistor R5 connected between the common point of the voltage divider bridge R1, R2 and the negative input of the comparator U1; and a resistor R8, a capacitor C1 installed in series by the common point, with the other end of C1 connected to the output of the comparator U1 and the other end of R8 connected to the common point of the two resistors R5, R8 and to the negative input of U1, the values of R5 and C1 being adjusted to set the intervention time of disconnection before the degradation of the battery when an overcurrent is detected.

[0035] According to another characteristic, a diode D2 is connected in parallel to the resistor R5, with the cathode connected to the common point of the voltage divider bridge to vary the integration time constant of the integration circuit when an overcurrent or short circuit occurs.

[0036] According to another characteristic, if the input voltage applied to the negative terminal of the amplifier U1 is greater than the value of the reference voltage V2, the comparator U1 has a voltage at its output, the value of which characterizes the "non-conductive" state, and if the input voltage applied to the negative terminal of the amplifier U1 is less than the value of the reference voltage V2, the comparator U1 has a voltage at its output, the value of which characterizes the "conductive" state.

[0037] According to another characteristic, the detection device comprises a capacitor C3 installed in parallel to R2, R2 being combined with R1 to form a filter to filter out high-frequency interference.

[0038] According to another characteristic, in parallel with R9 is installed

[0039] a series assembly consisting of the resistance R3, the diode D3 with cathode towards the positive terminal and the Zener diode D4 with cathode towards the common point of the voltage divider bridge R9, R4,

[0040] a capacitor C5 connecting the common point of the bridge R9, R4 to the negative terminal of the battery or of the modular assembly of cells or individual elements.

[0041] According to another characteristic, the comparator circuit U2 with hysteresis, provided downstream of the comparator circuit U1, comprises a hysteresis assembly around the amplifier U2 which receives at the input of its negative terminal the voltage value of the output of the amplifier U1.

[0042] According to another characteristic, the hysteresis comparator U2 comprises resistances R3, R4 installed as a voltage divider bridge between the positive and negative terminals of the battery and whose common point with R3 and R4 connects the positive input of the comparator U2 and also comprises a resistance R6 which connects the output of U2 to its positive input to define the threshold and the hysteresis of the hysteresis comparator circuit comprising the amplifier U2.

[0043] According to another characteristic, the detection device comprises a resistance R7 connected in the forward direction with the positive terminal of the battery during normal operation, in series with the diode D1 and a capacitor C2 connected on the one hand with the cathode of the diode and on the other hand with the negative terminal of the battery, so that it is possible to charge the battery during normal operation; the common point of D1 and C2 is connected to the power supply input of the two comparators U1, U2, which common point is used to maintain the power supply of the amplifiers U1 and / or U2 in the event of a collapse of the battery voltage after a short circuit, to allow the activation of the disconnection.

[0044] According to another characteristic, the reference voltage V2 of the positive input of the comparator U1 is provided by the Zener diode D2 connected by the resistance R1 to the common point of D1 and C2, the cathode of the Zener diode D2 also being connected to the negative terminal of the battery or of the modular element group by the capacitor C1.

[0045] According to another characteristic, the hysteresis comparator U2 comprises a capacitor connected in parallel with the resistance R4, which, in combination with another resistance R3 or R2, forms a filter to filter out high-frequency disturbances and to set a minimum trip time.

[0046] According to another characteristic, the positive input of the hysteresis comparator U2 is connected to the common point of R3, R9 and R7 by the resistance R2.

[0047] According to another characteristic, said detection device comprises a flip-flop connected to the output of U1 or U2 for storing each action of the detection device after each detection of a deep discharge, an overcurrent discharge and a short-circuit discharge.

[0048] Another object is to propose a disconnection device usable with the detection device, formed by electronic components associated with the assembly of the components of the safety disconnection device.

[0049] This other object is achieved by a disconnection device comprising a switching device (30), in which

[0050] A first MOSFET M1 is connected by its source to the negative terminal of a group of individual elements, said MOSFET M1 receiving on its gate a voltage source driving M1, said source providing a selected voltage to make M1 conductive,

[0051] a Zener diode D3, connected in reverse between the gate and the source of M1, a capacitor C2 protecting the gate of the MOSFET from excessive or high frequency voltages, and

[0052] a Zener diode D1, connected in reverse between the gate and the drain of M1, a resistor R3 and a diode D2 limiting the switching speed of M1 in the forward direction from drain to gate, and

[0053] a circuit consisting of a Schottky diode D4, connected in reverse on the drain of M1, and connected in series with a capacitor C1 and a resistor R1 to the positive terminal of the battery (4) to limit the overvoltage when opening M1, a fixed resistor I1 being connected in parallel on the Schottky diode D4, on the one hand to the cathode of the diode and on the other hand to the drain of a second MOSFET M2, the source of the second MOSFET M2 being connected to the anode of the Schottky diode D4, the gate of M2 being controlled by the output of the detection circuit to prevent the load.

[0054] According to another characteristic, said disconnection device comprises a second switching device, in which

[0055] The source of a first MOSFET M1 is connected to the negative terminal of a group of individual elements, the gate of said MOSFET M1 being controlled by a voltage, the source providing a selected voltage to make M1 conductive at all times,

[0056] a circuit consisting of a Schottky diode D4, connected in reverse on the drain of M1, a fixed resistor I1 being connected in parallel on the diode D4, on the one hand to the cathode of the Schottky diode D4 and on the other hand to the drain of a second MOSFET M2, the source of the second MOSFET M2 being connected to the anode of the Schottky diode D4, the gate of M2 being connected to the positive terminal of said group of individual elements,

[0057] a Zener diode D6 and a resistor R6 in series with the gate of M2, the Zener diode D6 being mounted in the forward direction in the drain-gate direction,

[0058] a Zener diode D5 mounted between the gate and the source of M2, defining with the Zener diode D6 the voltage value of the gate of M2 when M2 is on,

[0059] a capacitor C5 connected between the gate and the source of M2 and in parallel with the Zener diode D5 to protect the gate of M2 from high frequency voltages,

[0060] an optocoupler OP1 mounted between the gate and the source of M2 and in parallel with the capacitor C5 to block M2 when the voltage or the temperature of one of the components of a group of individual components is exceeded, then the MOSFET M2 cuts off the charging current.

[0061] Other characteristics and advantages of the application will be detailed in the following description. BRIEF DESCRIPTION OF DRAWINGS

[0062] Other characteristics, details and advantages of the application will become apparent on reading the following description, made with reference to the attached drawings, wherein:

[0063] Figure 1 a circuit diagram of a discharge detection device (2) for detecting deep discharge, overcurrent discharge and short circuit discharge according to one embodiment is shown;

[0064] Figure 2 a circuit diagram of said detection device according to one variant is shown;

[0065] Figure 3 a diagram showing an example of a circuit for measuring current by means of a resistor known from the prior art and having known drawbacks is shown;

[0066] Figure 4A a display of the voltage variation at the terminals of the comparators U1 and U2 in the case of overcurrent, according to one embodiment, of a 24.4 volt battery and of a detection or triggering voltage Td of 16 volts is shown;

[0067] Figure 4B a response of a digital integrator assembly according to the flowchart of Figure 4D according to one embodiment used with a 16 volt battery and a 12 volt detection or triggering voltage Td is shown;

[0068] Figure 4C a response of an analog integrator assembly according to another embodiment used with a 16 volt battery and a 12 volt detection or triggering voltage Td is shown;

[0069] Figure 4Dis a flow chart of a response calculation procedure for a digital integrator assembly illustrating an embodiment of a parallel analog embodiment;

[0070] Figure 4E shows the response of an analog integrator assembly according to one embodiment in a short circuit condition, used with a 14 volt battery and a 14 volt detection or trigger voltage Td in a short circuit condition;

[0071] Figure 4F shows the response of a digital integrator assembly operating according to the flow chart of Figure 4D in a short circuit condition, used with a 14 volt battery and a 10 volt detection or trigger voltage Td according to one embodiment;

[0072] Figure 4G shows the response of an analog integrator assembly according to one embodiment in a slow discharge condition, used with a 14 volt battery and a 14 volt detection or trigger voltage Td;

[0073] Figure 4H shows the response of a digital integrator assembly operating according to the flow chart of Figure 4D in a slow discharge condition, used with a 14 volt battery and a 10 volt detection or trigger voltage Td according to one embodiment;

[0074] Figure 4I shows the response of an analog integrator assembly according to one embodiment in a discharge at V / 2 condition, used with a 14 volt battery and a 14 volt detection or trigger voltage Td to determine the maximum current of the battery;

[0075] Figure 4J shows the response of a digital integrator assembly operating according to the flow chart of Figure 4D in a discharge at V / 2 condition, used with a 14 volt battery and a 14 volt detection or trigger voltage Td to determine the maximum current of the battery according to one embodiment;

[0076] Figure 5 shows a circuit diagram of a first switching device in a disconnect device discharge according to one embodiment;

[0077] Figure 6 shows a circuit diagram of a second switching device in a disconnect device discharge according to one embodiment;

[0078] Figure 7 shows an interconnection diagram between a battery management system (BMS) and a disconnect device according to one embodiment;

[0079] Figure 8a schematic view of a battery comprising a BMS and a disconnection device is shown according to one embodiment,

[0080] Figure 9 a disconnection characteristic diagram is shown according to one embodiment, the disconnection characteristic being obtained by the detection device as described and very close to the disconnection characteristic of a magnetic thermal circuit breaker of the state of the art. DETAILED DESCRIPTION

[0081] The present invention relates to a method and a system (1) for managing a battery (BMS).

[0082] The battery can consist of a single element or a plurality of single elements or cells and one electronic disconnection device (3), which elements or cells can be arranged in modular assemblies connected in series, in parallel, or in a plurality of modular assemblies connected in series, associated in parallel to constitute the battery (4), while the electronic disconnection device (3) is connected, on one hand, to at least one electrode of the battery and, on the other hand, to the terminals of the same electrode of the modular assemblies of the battery (4).

[0083] According to another variant, a battery management system (BMS) (1) for a battery (4) comprises at least one deep (or slow) discharge, overcurrent discharge and short circuit discharge detection device (2) in each single element or modular assembly of the battery (4) comprising at least one BMS device (1), Figure 8 a battery with BMS device is shown), said system (BMS) being characterized in that the detection device (2) is unique.

[0084] The detection device (2) comprises an analog or digital (Un) comparator U1 which compares directly, without using a shunt resistor, the voltage proportional to the voltage of the single element or of the modular assembly with a reference voltage (V2 or Refintegration) in a determined ratio and evaluates whether the voltage variation activates the disconnection of each single element or modular assembly of the battery (4) according to the detection voltage Td, where the disconnection device is activated according to the detection voltage Td.

[0085] The ratio between the measured voltage and the reference voltage corresponds to the ratio between the reference voltage (V2 or Refintegration) and the detection or tripping voltage Td that activates the disconnection device.

[0086] Figure 3 An example of current measurement of a shunt resistor is shown. This measurement involves the series connection of a shunt in the line. The total voltage V tot is given by V tot = V battery -V rshunt where V rshunt= R*I is the value across the shunt resistor. Thus, the greater I, the greater the voltage drop. In this case, the consumption of the comparator U1 is very high, 1 mA for the differential amplifier and less than 10 μΑ for the voltage measurement.

[0087] In addition, the voltage V battery measured across the terminals of the battery or of each element is in the form V battery = ER*I, where E is the open circuit voltage, R is the internal resistance and I is the current delivered by the battery. For a given battery, E and R are known, and the voltage V battery provides access to I (delivered current). The maximum power that the battery is able to provide is close to the value (E / 2)*(Icc / 2) (E is the open circuit voltage and I cc is the short circuit current). Since the internal resistance increases as the battery ages, the maximum power decreases as the battery ages. Disconnecting by monitoring the voltage V battery rather than the current provides the best protection for the battery throughout its lifetime. It is then clear that detection by measuring the voltage is advantageous.

[0088] In addition, in the event of a failure on one or both lines comprising a set of individual elements or battery cells, the detection device of the battery management system (BMS) (1) as described according to the application is configured to adapt the threshold or triggering voltage Td, in particular by voltage measurement detection, for detecting abnormal situations of the battery (deep discharge, short circuit discharge, overcurrent discharge). In other words, the detection device of the battery management system (1) can protect the battery regardless of its state of aging.

[0089] The individual battery elements of the battery (4) to be protected can for example and non-limitingly have the following characteristics:

[0090] Open circuit voltage = 3.3 V

[0091] Internal resistance = 0.012 ohms (with connection)

[0092] Maximum current = 70 A; 120 A for 10 seconds

[0093] Discharge termination voltage = 2 V

[0094] Charge termination voltage = 3.6 V

[0095] Maximum voltage = 4 V

[0096] The battery (4) can be modeled by an ideal voltage source in series with an internal resistance. For example, in the case of an "8S1P" assembly consisting of 8 single elements in series, there is, for example but not limitatively, an open circuit load (or charge termination) voltage of 26.4V and an internal resistance of 0.1 Ohm (with connections). Therefore, the short circuit current can reach 264A, while the maximum rated current is 120A for 10 seconds. Therefore, overcurrent protection is necessary.

[0097] Figure 1 It is shown that the claimed circuit for detecting a fault (abnormal condition) comprises a voltage divider R1 and R2, a voltage reference V2 of 1.24V, V1 being, for example but not limitatively, the voltage of the terminals of the battery monitored by the device. In the example above, the voltage at the end of discharge must not be lower than 2V per battery, i.e. 16V for 8 batteries in series. V1 = 16V can then be chosen as the value of the detection or trigger voltage Td. For this detection or trigger voltage value, the voltage division ratio of the voltage divider R1 and R2 will be chosen equal to V2 / Td; i.e. 1.24V / 16V = 0.0775. Therefore, in static operation, when the voltage of the battery (4) is greater than the detection or trigger voltage Td = 16V, the voltage applied to the input of the amplifier U1 is greater than 1.24V, its output is in the "non-conductive" state, the output of the comparator U2 is in the "conductive" state, the operation is "normal" (no disconnection).

[0098] When the battery (4) is slowly discharged (deep discharge) and its voltage drops below 16V, the voltage applied to the input of the amplifier U1 is less than 1.24V, its output goes into the "conductive" state, the output of the comparator U2 switches to "non-conductive" and activates the disconnection. According to the analog embodiment [Figure 4c] or another digital embodiment Figure 4B ] the output of the comparator (amplifier) U1 is the integral of the voltage to be monitored. Therefore, as shown in these figures, if the voltage V global varies linearly, the output of the integrator will be a quadratic function. If the voltage variation is linear of the form ax + b, the output is a function of the type ax 2 + bx + c.

[0099] In the expression of the voltage across the terminals of the battery or of a single cell of the battery given by V battery = ER * I, the open circuit voltage E decreases when the battery is fully discharged.

[0100] When the battery (4) provides a large current (overcurrent), for example 120A, its voltage drops rapidly to 14.4V (curve V1 Figure 4A ). The assembly of the above detects this situation.

[0101] In the event of a short circuit, the voltage VI drops very quickly to a very low value and the voltage across the terminals of R2 is close to 0V; this situation is also detected.

[0102] By replacing resistors R1, R2 with resistors R9, R4, this same assembly can be used in another variant embodiment of the application (assembly with Zener diode D4). Figure 2

[0103] The detection device as described in the present application allows to detect voltage variations with non-linear progression, so that a strong overcurrent causes the battery to disconnect after a period of time between 10 ms and 100 ms, while a low overcurrent would cause the disconnection in a time between 10 seconds and 100 seconds.

[0104] An overcurrent or short circuit causes the battery assembly to overheat, which can cause a fire. The dissipation of heat is proportional to the square of the intensity, so the disconnection must be faster because the overcurrent is important. A fuse or a thermomagnetic circuit breaker cuts off the current in a shorter time because the overcurrent is important. This involves setting a maximum current and low battery protection to prevent the battery assembly from aging because the battery ages with an increase in internal resistance and is unable to withstand a certain maximum of current. In other words, once aging occurs, the fixed maximum current is not reached and the detection and protection of the battery do not work. On the contrary, in the present application, the overcurrent detection device is particularly based on the measurement of the voltage across the terminals of the battery as a function of time, without constraints associated with the setting of a maximum current. If the measured voltage is lower than a certain value corresponding to a low intensity current, the disconnection time is long, as shown in Figure 9 . If the measured voltage is lower than a certain value corresponding to a large current or short circuit, the disconnection time is short (see Figure 9 ). This makes it possible to protect the battery regardless of whether its assembly is aged or not.

[0105] The detection function achieved by measuring the battery voltage and in combination with the use of an electromagnetic circuit breaker makes it possible, among other things, to simulate the behavior of a thermomagnetic circuit breaker without the need to set a limit on the maximum current to improve the safety of the battery. For example, Figure 9 , the electronic circuit breaker according to the present application obtains a disconnection curve similar to that obtained by a shunt measurement and a thermomagnetic circuit breaker, but with greater precision.

[0106] The embodiments provide additional protection for the operation of the circuit to maintain the service life of the assembly or to avoid having to choose expensive components because they meet high specifications. These embodiments can not be combined with each other in their entirety or with the main embodiment.

[0107] The detection device (2) therefore comprises a voltage divider formed by at least two resistors R1 and R2, which is connected to the terminals of the battery (4) to reduce the voltage at the input of the comparator U1. ​

[0108] Similarly, a resistor R5 is connected between the common point of the voltage divider bridge R1 and R2 and the negative input terminal of comparator U1. A resistor R8 and a capacitor C1 connected in series at the common point are connected to the output terminal of comparator U1 through the other end of C1. The other end of R8 is connected to the common point of the two resistors R5 and R8 and the negative input terminal of U1.

[0109] In another embodiment, diode D2 is connected in parallel with resistor R5, and the cathode of diode D2 is connected to the common point of the voltage divider bridge. In this configuration, diode D2 can change the integration time constant of the integrator component in the event of a very large or high current inrush, such as in the event of an overcurrent or short circuit. In the case of a digital integrator, this change in the integration time constant is equivalent to using weighting in the signal (voltage) integration (see below).

[0110] Therefore, in the case of overcurrent, such as Figure 4A As shown, battery (4) provides a large current, such as 120A, and its voltage drops rapidly to 14.4V (V1, Figure 4A The voltage difference between 26.4V and 14.4V is integrated by the integrator circuit R5-R8-C1 (in a mathematical sense) connected to the terminals of amplifier U1, and the integration constant depends primarily on R5-C1. Its output (V... integr , Figure 4A The voltage slowly changes from "0V" to "Vcc short-circuit voltage", and when its threshold (V4, Figure 4A When the detection or trigger voltage Td is reached, the hysteresis comparator U2 switches (V3, Figure 4A ) Activate disconnection. In this case, set the time constant R5–C1 so that disconnection occurs 10 to 12 seconds in advance.

[0111] During the short circuit, voltage V1 drops very rapidly to a very low value and the voltage across R2 approaches 0V. Diode D2 conducts, the voltage at the input of U1 is 0.6V (the + input remains 1.24V), and the voltage at the output of U1 quickly becomes "Vcc". The output of comparator U2 becomes "0", and the disconnection is activated.

[0112] In all these cases, the trigger stores the action, and it is necessary to “reset” (that is, re-preset) the battery (4) by operating the “start” button that can be accessed from outside the battery casing.

[0113] Capacitors C3 and / or C4 filter out any high-frequency interference and set the minimum trip time.

[0114] The integration circuit measurement principle described in this application is a total voltage measurement principle that can trace back to the current value. This principle is only applicable in the field of batteries if the internal resistance of the voltage generator is known. In this case and only in this case, the integrator assembly can be used using analog (as shown in Figure 1 ) or digital means.

[0115] For example, but not limited to, the response or output of the digital integrator can be calculated as follows:

[0116] Consider the voltage variation represented by "x = (-0.25 * V global + 2.5) * Weighted", where V global is the voltage obtained from the battery voltage using the voltage divider bridge (R1-R2 or R9-R4) and "Weighted" is a variable that allows the integration constant to vary. The above equation can be modified according to the battery used.

[0117] The output or response of the digital integrator with the general form y = Integration(x), where Integration() represents the integral calculus, can be calculated using either of the following as a first asymptotic equation, where it includes taking the value of x, as defined above, and raising it to an even power (2, 4, 6, 8, etc.), for example y = x 2 .

[0118] To be closer to the analog integrator, Figure 4A , Figure 4C a second asymptotic equation can be used, for example, and not limited to, defined by y = Rate * (-ln(x)), where Rate is the integration constant expressed in seconds. This equation can simulate the behavior of a capacitor whose terminal voltage evolves like an exponential.

[0119] Figure 4D A graph showing the calculation of the response of the digital integrator according to the second asymptotic equation is shown. Each calculation step represents an assembly of the detection device that can participate in the calculation operation. The graph can be divided into three stages: the measurement (PM) and comparison stage, the integration stage (PI) and the disconnection stage (PD).

[0120] In the measurement stage (PM), the voltage divider bridge R1-R2 (or R9-R4) can determine the measurement V = V global .

[0121] The "Refintegration" variable is the integration reference, corresponding to a voltage value below which the input signal V will be integrated. If the voltage V is greater than the "Refintegration" variable, the battery is in normal operation. If V is less than the "Refintegration" variable, the battery is operating abnormally and triggers a process that can lead to the disconnection of the battery. This variable "Refintegration" is therefore equivalent to a reference voltage V2. The integration phase is then entered, for which the response of the integrator must be calculated.

[0122] If the voltage V is lower than the "Refintegration" variable, the program will trigger the use of the normal integration constant in the calculations performed, or the use of a weighting on the integration constant. If the voltage is lower than a second comparison variable called "RapidThreshold", a weighting is used as represented in the PI block, which makes it possible to define a voltage threshold according to which it is determined whether to use its "Weighting" variable (defined above) in the calculation of the voltage variation or not. For example and non-limitatively, the voltage variation has the general form "x = (slope * V global + ordinate) * weighting".

[0123] If the difference or variation of the input voltage V, dV, between a time tl and a time t2 (or between two successive measurements of the voltage V) defined by dV = |V(t2) - V(tl)| is greater than the "RapidThreshold" variable, the "Weighting" variable takes for example the value 5. Conversely, if said difference or variation of the input voltage V, dV, is less than the "RapidThreshold" variable, the "Weighting" variable takes the value 1. This corresponds to the use of the normal integration constant.

[0124] The voltage measurement time interval can be, for example and non-limitatively, between 1 and 100 milliseconds. The value of the "RapidThreshold" variable can be defined according to the measurement time interval and by monitoring the voltage variation between two times tl and t2 corresponding to said time interval for performing a voltage measurement, in order to improve the conditions for detecting abnormal situations. For example, and non-limitatively, for a measurement time interval of 10 milliseconds, the "RapidThreshold" value is 0.01 volts. This corresponds to a pressure drop dV = 0.01 V every 10 milliseconds. Figure 4B

[0125] ​The voltage change can be defined by deriving the "slope" (for linear voltage changes) and then the "ordinate" by storing measurement points and, for example, by fitting the stored voltage data or by using two points from a stored voltage curve between two times t1 and t2. In the example "x = (-0.25 * Vglobal + 2.5) * weighted", the slope is -0.25 and the ordinate is 2.5.

[0126] The step of comparing the voltage change dV is equivalent to comparing the calculated slope with the stored “Rapid Threshold” value. If the slope exceeds the “Rapid Threshold” value, a weighting factor (e.g., 5) is applied to increase the acceleration of the integral evolution, causing it to cross the trigger voltage threshold Td more quickly. Alternatively, if the slope does not exceed the threshold, a weighting factor (e.g., 1) without acceleration effect is used.

[0127] Once the voltage change is obtained, the signal can be integrated, for example, according to the second asymptotic equation. Therefore, the output signal corresponds to the integral of the input signal.

[0128] The variable “Progressivenss coeff” corresponds to the integration constant (the rate in the second asymptotic equation).

[0129] In embodiments of the digital integrator, those skilled in the art will understand that the components using comparators U1 and U2 are replaced by a microprocessor that acts as a digital comparator (Un). This microprocessor is equipped with memory that allows storage of "Refintegration" and "RapidThreshold" threshold variables, as well as "ordinate" and "slope" calculation variables defined according to these thresholds. The memory also contains a calculation program that allows the collection of voltage curve points (V... global (etc.), comparison and decision-making, implementation of equations, integration and... Figure 4D The decision is illustrated in the flowchart. As input, the digital circuit receives voltage V only from the common point of the voltage divider bridge between resistors R1 and R2. global And measurements are taken at a determined frequency to observe the voltage V. global The curve, and then from the detection of "Ref" integration "Threshold crossover, in" Figure 4B In the example shown, the selected threshold is less than 3V per cell or 12V for a battery with four cells connected in series with the reference voltage V2. The microprocessor program triggers calculations to obtain the voltage V between two consecutive times t1 and t2 (or between two consecutive measurements). globalthe "RapidThreshold" variable of the variation dV to determine whether to use the "Weighted" variable. Thus, in the case of a start that causes a significant drop in voltage from 14 volts to almost 6 volts, the "RapidThreshold" variable is for example and not limitatively set to 0.01 volts in the example shown in Figure 4B the "Rapidthreshold" variable will be crossed and the integration will be done by weighting to avoid a too rapid cut-off that prevents the start. In the example shown in Figure 4B the graph shown in the example, we observe that the battery voltage has rapidly dropped to almost 6 volts and remains constant for about 18 seconds, the digital circuit integrates the constant value as a straight line that remains below the detection or trigger voltage Td selected at 1 V. The response of the integrator or output voltage can be obtained for example and not limitatively by a program such as defined in the appendix of the present application, where the "GeneralVoltage" variable corresponds to the voltage V global at the instant t1 = t, and the "LastGeneralVoltage" variable represents the value of the voltage V global at the instant t2 = t-1. The "ORDINATE_ORIGIN" variable corresponds to the "Ordinate" variable defined above, and the "lastIntegratedValue" variable corresponds to the response of the integrator or integrator calculation.

[0130] The calculation of the integration or integrator response can include taking into account the "Slope and / or Ordinate" variable, calculated by the microprocessor from the recorded voltage curve V global data.

[0131] Once the total voltage V global drops to V2 = Ref integration = 9 V, the integration is triggered.

[0132] Then, during use, the voltage of the battery will suddenly drop from 14 V to around 9 V and then slowly decrease along a straight line to 6 V over time. The ordinate of the line is about 2.3 V and the slope is lower than before, the voltage variation dV between two successive measurements can be greater than (depending on the value of the slope) the "Rapidthreshold" variable (for example, 0.01 V in the example shown in Figure 4B ).

[0133] When the value of the integration output reaches the threshold corresponding to the detection or trigger voltage Td of 1 volt, the cut-off is triggered.

[0134] Finally, in the digital version or variant, during the short circuit, the voltage V globalVery rapidly drops to a very low value, the short-circuit detection threshold is stored, and as soon as the processor detects the crossing of this threshold, it activates the disconnect signal.

[0135] Figure 4B The response or output signal of the digital integrator according to the above example is illustrated, the digital integrator exhibits a behavior similar to the analog integrator ( Figure 4C ) during the time interval between t = 40 s and approximately t = 120 s.

[0136] During the disconnect phase, the calculation of the response serves to check whether the disconnect should be triggered (or activated). The disconnect is activated when the response of the integrator is greater than a given threshold corresponding to the detection or triggering voltage Td. In the above example illustrated, Figure 4B 、 Figure 4C and Figure 4D this threshold is set to approximately 1 V or 1.24 V. For example and without limitation, this threshold can be normalized to 1.

[0137] 4E and Figure 4F illustrate the response of the analog integrator and the digital integrator, respectively, when a short circuit is detected. The measurement time step is set to 10 ms and the value of the "RapidThreshold" variable is equal to 0.1 V.

[0138] In the example illustrated in Figure 4F , which shows the response of the digital integrator, it can be observed that the voltage V global drops from a value of approximately 14 V to a value close to 0 V during the time interval between 0.2 s and 0.3 s, where the digital integration circuit integrates the input signal with a weighting value of 150 to increase the acceleration of the evolution of the integration. This weighting is performed to make the output signal or response cross the triggering threshold Td = 10 V (set to 14 V in the case of the analog integrator) as quickly as possible. As mentioned above, the value of Td can be normalized to 1. From 0.3 s to approximately 4.2 s, the value of V global remains constant and close to 0 V, the response of the digital integration circuit is a straight line that passes above the triggering voltage Td of the disconnect after a duration of approximately 1 s. When the battery resumes normal operation, after 4.2 s, the response of the digital integrator circuit is zero. The behavior of the digital integrator is similar to that of the analog integrator circuit illustrated in Figure 4E .

[0139] Figure 4G and Figure 4H illustrate the response of the analog integrator and the digital integrator, respectively, when a slow or deep discharge is detected. The measurement time step is also set to 10 ms and the value of the "RapidThreshold" variable is equal to 0.1 V.

[0140] As Figure 4HDuring slow or deep discharges, the signal or input voltage V global decreases linearly from 14 V to about 5 V in the time interval between 0 and 116 seconds. The input signal is integrated by the digital integrator circuit (or digital integrator), taking into account a weighting value equal to 150. The opening process is triggered when the response curve is greater than the value of the trigger voltage Td, which in this case is set to about 10 V (in the case of an analog integrator it is set to about 14 V). As in the case of detection of abnormal conditions such as overcurrent Figure 4B ), short circuit Figure 4F ), etc., in the case of slow discharges, the behavior of the digital integrator is similar to that of the analog integrator circuit shown in Figure 4G .

[0141] Therefore, the person skilled in the art will understand that the battery management system as described in this application is suitable for detecting abnormal conditions including at least overcurrent, short circuit and slow or deep discharges. The detection can be carried out without having to change the electronic components of the unique detection device, or without having to integrate new electronic components depending on the set of abnormal conditions one wishes to detect. Another advantage is that the detection device does not have to include as many electronic circuits as the abnormal conditions to be detected. This makes it possible to avoid overloading the management system, which would create maintenance problems in the event of a malfunction, in particular when looking for the source of the malfunction.

[0142] Figure 4I and 4J illustrate the response of the analog integrator and the digital integrator, respectively, to a V / 2 discharge. In the case of a V / 2 discharge occurring in a short time, for example about 15 seconds, it is possible to determine the maximum current supported by the battery.

[0143] In some embodiments, a battery management system (BMS) for a battery (1) comprises at least one comparator U1; a voltage divider bridge (R1, R2 or R9, R4) installed between the terminals of a modular assembly of the battery (4) or of a single cell of the battery (4), which connects the input of the negative terminal of the comparator U1 to the common point of the resistors to provide a voltage value proportional to the voltage V1 by the ratio defined by the values of the two resistors (R1, R2 or R9, R4), and the positive terminal of the comparator is connected to a diode or to a power cell (not shown) to define a reference voltage V2.

[0144] In some embodiments, the integrator assembly comprises a resistor R5 connected between the common point of the divider bridge R1, R2 and the negative input of the comparator U1; and a resistor R8, capacitor C5 assembly connected in series by a common point, the other end of C5 being connected to the output of the comparator U1 and the other end of R8 being connected to the common point of the two resistors R5, R8 and to the negative input of U1, the values of R5 and C1 being adjusted to set the intervention time for the disconnection before the deterioration of the battery (4) upon detection of an overcurrent.

[0145] In some embodiments, if the input voltage applied to the negative terminal of the amplifier U1 is greater than the value of the reference voltage V2, the comparator U1 has at its output a voltage value that characterizes the "non-conductive" state, and if the input voltage applied to the negative terminal of the amplifier U1 is less than the value of the reference voltage V2, the comparator U1 has at its output a voltage value that characterizes the "conductive" state.

[0146] In some embodiments, the detection device (2) comprises a capacitor C3 connected in parallel to R2, R2 forming a filter in combination with R1 to filter out high frequency interferences.

[0147] In some embodiments, in parallel to R9 is a series assembly consisting of a resistor R3, a diode D3 with cathode towards the positive terminal and a Zener diode D4 with cathode towards the common point of the divider bridge R9, R4, a capacitor C5 connecting the common point of the bridge R9, R4 to the negative terminal of the battery (4) or of the modular assembly of cells or individual elements. (R3, C5) can be configured to obtain a fast time constant and (R9, C5) can be configured to obtain a slow time constant.

[0148] In some embodiments, the comparator circuit U2 with hysteresis, provided downstream of the comparator circuit U1, comprises a hysteresis assembly around the amplifier U2, which receives at the input of its negative terminal the voltage value of the output of the amplifier U1.

[0149] In some embodiments, the hysteresis comparator U2 comprises resistors R3, R4, connected as a divider bridge between the positive and negative terminals of the battery (4) VI, its positive input being connected to the common point of R3 and R4 and also comprises a resistor R6 connecting the output of U2 to its positive input to define the threshold and hysteresis of the hysteresis comparator circuit comprising the amplifier U2.

[0150] In certain embodiments, the detection device (2) comprises a resistor R7 connected in series with the positive terminal of the battery (4) along the forward direction during normal operation, in parallel with a diode D1, and a capacitor C2 connected on the one hand to the cathode of the diode and on the other hand to the negative terminal of the battery (4), so that it is possible to charge the battery during normal operation; the supply input of the two comparators U1, U2 is connected to the common point of D1 and C2, which is used to maintain the power supply of the amplifier U1 and / or U2 in the event of a short circuit, which causes the battery (4) voltage to collapse, to allow the activation of the disconnection.

[0151] In certain embodiments, the reference voltage V2 of the positive input of the comparator U1 is provided by a diode D2, which is a 16V Zener diode. This diode is also connected to the common point of D1 and C2 through a resistor R1. The cathode of the diode D2 is also connected to the negative terminal of the battery (4) or of the modular assembly of elements through a capacitor C1. The diode D2 can also be replaced by a voltage reference.

[0152] In certain embodiments, the hysteresis comparator U2 comprises a capacitor (C4, Figure 1 or C3, Figure 2 ) connected in parallel with a resistor (R4, Figure 1 or R3, Figure 2 ), which, together with another resistor (R3, Figure 1 or R2, Figure 2 ), forms a filter to filter out high-frequency disturbances and set a minimum tripping time.

[0153] In certain embodiments, the hysteresis comparator U2, Figure 2 the positive input of which is connected to the common point of R3, R9 and R7 through a resistor R2.

[0154] In certain embodiments, the detection device (2) comprises a flip-flop connected to the output of U1 or U2, for storing each action of the detection device (2) after each detection of deep discharge, overcurrent discharge and short-circuit discharge.

[0155] In certain embodiments, the battery management system (BMS) (1) communicates with the disconnection device (3) contained in the battery through the detection device (2). The disconnection device is connected on the one hand to the negative terminal of each module block or of each battery and on the other hand to the negative terminal of the battery (4) and uses at least two MOSFETs (M1, M2).

[0156] In another embodiment, the battery management system (BMS) (1) comprises, for example, Figure 7The disconnection device (3) is shown in communication with the detection device (2). The disconnection device is connected on one side to the negative pole of each module or of each battery and on the other side to the negative terminal of the battery (4) and uses at least two MOSFETs (M1, M2).

[0157] The disconnection device (3) comprises switching means (30, 31) which can be electromechanical, for example relays, or semiconducting.

[0158] Preferably, the disconnection device should have a very low static consumption in both the open (conducting) and closed (non-conducting) states. By way of example but not limitation, bistable relays or MOSFET transistors meet this requirement.

[0159] In certain embodiments, the disconnection device (3) comprises a first switching means (30) in which

[0160] A first field effect transistor (MOSFET) M1 is connected by its source to the negative terminal of a group of individual elements, this MOSFET M1 receiving on its gate a voltage source (from the output of the comparator U1 in the variant of Figure 2 , or from the output of the hysteresis comparator U2 in the variant of Figure 1 ) which drives M1. This source provides a selected voltage (for example 6 to 10 V) so that M1 is conducting;

[0161] A Zener diode D3 is connected in reverse between the gate and the source of M1, a capacitor C2 protecting the gate of the MOSFET from excessive or high-frequency voltages; and

[0162] A Zener diode D1 is connected in reverse between the gate and the drain of M1 and limits the switching speed of M1 in the direction drain to gate, together with a forward resistance R3 and a diode D2; and

[0163] A circuit consisting of a (conventional) diode or Schottky diode D4 is connected in reverse on the drain of M1 and in series with a capacitor C1 and a resistance R1 connected to the positive terminal of the battery (4) to limit the overvoltage when M1 is opened.

[0164] A resistance, for example a fixed or variable resistance II, is connected in parallel on the diode or Schottky diode D4, connected on one side to the cathode of the diode and on the other side to the drain of a second MOSFET M2, the source of which is connected to the anode of the diode or Schottky diode D4. The gate of M2 is controlled by the output of the analog or digital detection circuit, preventing or cutting off the load or charging current Figure 7 . The resistance II can limit the charging current.

[0165] Figure 5A first switching element (30) and a discharge switch are shown.

[0166] In this embodiment, the battery (4) is used by an external device (5), for example but not limited to a starter characterized by an L1-R5 pair.

[0167] When the battery (4) is discharging, diode D4 is conducting. It must be able to withstand at least 10 milliseconds of short circuit current and dissipate the Joule losses during a large current discharge. In the case of a battery (4) consisting of an "8S1P" assembly of 8 single cells in series, with an open circuit voltage of 26.4 V and an internal resistance of 0.1 Ohm (with connections), the short circuit current can reach 264 A.

[0168] When M1 is opened, an overvoltage greater than the drain-source voltage Vds of M1 can occur due to the cancellation of the current in inductor L1. D3 and C2 then act as a filter, protecting the gate of MOSFET M1 from too high or high frequency voltages and preventing it from being destroyed.

[0169] Zener diode D1, resistor R3 and diode D2 can limit the switching speed of M1 so that it does not oscillate. The switching (voltage) is defined by the opening and closing of MOSFET M1, in other words by its off state and on state.

[0170] In certain embodiments, the disconnecting device (3) comprises a second optocoupler switching device (31), wherein

[0171] A first MOSFET M1 is connected by its source to the negative terminal of the group of single elements, the gate of this MOSFET M1 is controlled by a voltage, this source provides a selected voltage so that M1 is always conducting,

[0172] A circuit consisting of a (conventional) diode or a Schottky diode D4, reverse mounted on the drain of M1, with a fixed resistor I1 in parallel mounted on the Schottky diode D4, the fixed resistor I1 being connected on the one hand to the cathode of the Zener diode D4 and on the other hand to the drain of a second MOSFET M2, the source of the second MOSFET M2 being connected to the anode of the Schottky diode D4, the gate of M2 being connected to the positive terminal of the group of single elements,

[0173] A Zener diode D6 and a resistor R6 are connected in series with the gate of M2, the Zener diode D6 being forward mounted in the drain-gate direction,

[0174] A Zener diode D5 is mounted reverse between the gate and the source of M2, defining with the Zener diode D6 the voltage value at the gate of M2 and when M2 is conducting,

[0175] a capacitor C5 connected between the gate and the source of M2 and in parallel with a zener diode D5 to protect the gate of M2 from high frequency voltage,

[0176] a photocoupler OP1 mounted between the gate and the source of M2 and in parallel with the capacitor C5, which can block M2 when the voltage or the temperature of the cell or of a group of single cells is exceeded, then the MOSFET M2 cuts the charging current.

[0177] The proper value of the fixed resistance II can be obtained by replacing it with a variable resistance and by dynamically modifying its value, for example but not limitatively by means of an analog.

[0178] Figure 6 The second switching device (30) and the load cut-off are shown.

[0179] In this embodiment, the battery (4) is charged by means of an external device (5), for example but not limitatively an alternator or a charger characterized by the pair V4-R5.

[0180] The external device provides, in normal operation, for example but not limitatively 28V, but can output a higher voltage in case of malfunction of its regulator. The voltage given by the standardized tests is 1.5 times the nominal voltage of the battery, i.e. 42V. In practice, this voltage can reach 80V.

[0181] The limitation of the charging current is provided by a diode D4, which is on in the discharge direction and off in the charging direction, in parallel with a current-limiting resistance.

[0182] The diode D4 must therefore withstand the short-circuit current. This is feasible for a module battery, but it is very difficult for a large capacity battery. In fact, for example, a 17 Ah non-modular battery can provide a short-circuit current of over 1800 A. Therefore, the diode should be able to carry this current. Diodes that can carry this current do not exist as "electronic components", in fact it is possible to parallelize several lower current components. However, it is almost impossible to balance the diode currents in parallel, since the forward voltage drops sharply with temperature. Therefore, the hottest diode carries all the current, which further raises its temperature until it is destroyed.

[0183] The MOSFET M1 is configured to be always on at its gate. The diode D4 is blocked when charging, the charging current passing through II and M2. II can also be a combination of a resistance and a multi-switch, or a semiconductor current regulator. For example, when the gate-source voltage V gs of M2 is 10V, M2 is on.

[0184] D6 is for example a 18V Zener diode, D5 is a 10V Zener diode. Thus, at a voltage of 28V (alternator or charger voltage), D6 and D5 are at the conduction limit, no current in R6 and V gs = 10V. The voltage values of diodes D5 and D6 thus enable to define the gate-source voltage value of MOSFET M2. C5 protects the gate of MOSFET M2 from high frequency voltage.

[0185] The detection of a charger failure comprises two measurements: the measurement of the voltage of each element, and the measurement of the total voltage. If the voltage of one element exceeds 4V or if the total voltage exceeds 32V, the switching device (31) for switching to the load is activated. When the voltage drops below 26V (for example, due to a hysteresis comparator), the charging can be resumed.

[0186] In a digital variant, a microprocessor would be connected to the battery to receive at its inputs the voltage V cec representing the voltage of each cell element making up the battery, and the total voltage measurement V global of the battery, which can be measured on the conductors leading to the external terminals of the battery. The program executable by the microprocessor would comprise a code module for monitoring these two voltages V cec and V global ; after comparing each voltage to a respective determined stored threshold, it triggers the cut-off by activating the disconnection element (31) when this threshold is exceeded.

[0187] If the voltage or temperature of a single element is exceeded, M2 is blocked by the optocoupler OP1. Indeed, the optocoupler OP1 comprises a LED (Light Emitting Diode) and a transistor. Thus, if the voltage or temperature of a single element is exceeded, a current flows through the LED and causes the transistor to conduct. The gate-source voltage V gs of MOSFET M2 returns to close to 0V (V cesat , the saturation collector-emitter voltage of OP1). M2 then cuts off the charging current (D4 and M2 are blocked).

[0188] The current in the LED of OP1 is taken from the common point between M1 and the battery, and thus from the voltage of the battery (4), as shown in Figure 6 , which results from the disconnection of the battery 0V from the alternator or charger 0V.

[0189] Another alternative embodiment of the detection device is possible by using a low-pass RC circuit, non-linear elements (diodes and Zener diodes) and a comparator U1. There is an overvoltage detection assembly around the comparator U2.

[0190] It should be noted that this variant is also based on a voltage comparison made using the voltage divider bridge R9, R4 and the comparator U1 which sends the disconnection signal directly to the Figure 3 and the disconnection assembly shown in Figure 4. The assembly also uses the same principle, powered by R7, D1, C2 of the comparators U1 and U2 to ensure detection even when the voltage of the battery (4) collapses due to a short circuit.

[0191] U2[ Figure 2 ] hysteresis installation for R5, R6, C3 is the same as U2[ Figure 1 ] hysteresis installation for R6, R4, C4. Figure 2

[0192] The positive input of the hysteresis comparator U2[ Figure 2 ] is connected to the common point of R3, R9 and R7 through the resistance R2.

[0193] The Zener diode D2 is connected on the one hand to the positive input of the hysteresis comparator U2 and on the other hand to the common point of D1 and C2 through the resistance R1. The cathode of the diode D2 is also connected to the negative terminal of the battery (4) or of the modular assembly of elements through the capacitor C1.

[0194] In parallel with R9, a series assembly is installed, consisting of the resistance R3, the diode D3 with its cathode towards the positive terminal and the Zener diode D4 with its cathode towards the common point of the voltage divider bridge R9, R4. The capacitor C5 connects the common point of the bridge R9, R4 to the negative terminal of the battery (4) or of the cell or of the modular assembly of cells.

[0195] In operation, as mentioned previously, VI represents the voltage of the battery (4). The reference voltage V2 of the positive input of the comparator U1 is provided by the diode D2, which is a 16V Zener diode here. This diode is also connected to the common point of D1 and C2 through the resistance R1. The cathode of the diode D2 is also connected to the negative terminal of the battery (4) or of the modular assembly of elements through the capacitor C1. Thus, the diode D2 is biased by R1 and filtered by C1. The voltage of the battery (4) is divided by R9 - R4, so that when the voltage of the battery (4) slowly reaches the end of life voltage (or EPV, which is 18V for a 24V battery and 9V for a 12V battery), the voltage at the negative input of U1 becomes 16V, which causes the comparator U1 to switch from the "conductive" state to the "non-conductive" state (or from 1 to 0 using the binary method).

[0196] ​Below the end-point voltage or EPV, the time constant of R9 - C5 causes U1 to switch with a typical delay of 1 to 30 seconds. The delay is shorter because the voltage is much lower than the EPV. For very low voltages corresponding to strong overcurrents or short circuits, R3, D3 and D4 are in parallel with R9, thus shortening the switching time of U1 to less than one second (typically 0.1 seconds). For example, D4 is a 4.7V Zener diode.

[0197] Thus, in reading the above features, the BMS provides:

[0198] a single device providing short-circuit, overcurrent and deep-discharge protection simultaneously;

[0199] overcurrent detection for triggering the cut-off by voltage measurement;

[0200] trip current that automatically adapts to the battery characteristics;

[0201] no shunt, no magnetic sensor, no heating element disconnect curve similar to the thermal-magnetic curve but with higher precision Figure 9 ;

[0202] disconnect curve that changes with the aging of the battery elements;

[0203] no need for further adjustments.

[0204] The management system as depicted in this application has other advantages, including but not limited to:

[0205] very low static consumption;

[0206] circuit always on, no "boot" and "sleep" modes;

[0207] very high operating safety (high MTBF);

[0208] BMS uses standard, non-strategic and non-specific-purpose components;

[0209] for analog embodiments: no software, no sequential logic, no clock, which avoids software problems and thus battery degradation in case of software problems;

[0210] no electromagnetic radiation and better electromagnetic immunity (this is because low-power components are used).

[0211] Various technical features and various advantages described herein are presented with reference to the accompanying drawings and / or various embodiments. Persons skilled in the art will understand that the technical features of a given embodiment can be combined with technical features of another embodiment, unless the features are mutually exclusive, unless otherwise indicated, or unless the combination is not technically feasible. Additionally, technical features described in a given embodiment can be isolated from other technical features of that embodiment, unless otherwise indicated.

[0212] Those skilled in the art will appreciate that the application allows a great variety of other specific forms of implementation, without departing from the scope of the claimed application. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, and the application should not be limited to the details presented above, but can be modified within the scope of the protection sought.

[0213] Attachment:

[0214] This corresponds to a non-limiting example of a digital integrator program to achieve Figure 4B the response of the integrator in

[0215]

[0216]

Claims

1. A method for detecting abnormal operating conditions of a single cell element or of a plurality of groups of single elements, comprising the steps of: - sampling at least one voltage at the common point of at least two resistors of a voltage divider bridge, said at least one voltage being proportional to the voltage at the terminals of a single element or of a group of single elements; - comparing the detected voltage with a reference threshold; characterized in that said comparison with said reference threshold triggers the implementation of the following: - the calculation of an evolution by analog or digital integral evaluation; - the comparison of this calculated value with a detection voltage threshold Td, according to which the single element or the group of monitored single elements is at least disconnected from said battery terminals.

2. The method of claim 1, wherein, The step of obtaining the calculated value of the digital integral comprises: - a step of calculating the evolution slope (P) of the voltage curve by using at least two measurements taken from: - at least one step of comparing the calculated slope with a stored "RapidThreshold" value, i.e. if the slope exceeds the "RapidThreshold" value, a weighting factor is applied which increases the integral evolution acceleration so that it crosses the voltage threshold Td more quickly, or if it does not, a weighting factor is applied which has no acceleration effect.

3. A battery management system (BMS) (1) for a battery, which can be composed of a single element or a plurality of single elements, which can be arranged in modular assemblies and in series, in parallel or arranged in a plurality of series modular assemblies in a plurality of parallel associations, forming a battery (4), characterized by, The system comprises means for implementing the steps of the detection method as claimed in any one of the preceding claims.

4. The battery management system (BMS) (1) for a battery of claim 3, characterized by, It comprises at least: - a voltage divider bridge with at least two resistors (R1, R2 or R4, R9) for sampling at least one voltage proportional to the voltage at the terminals of a single element or of a group of single elements of a battery, - a detection device (2) for detecting abnormal conditions, - a disconnection device (3), said detection device (2) communicating with said disconnection device (3) to activate it when an abnormal condition is detected, said disconnection device being connectable to said battery (4) and comprising at least two MOSFETs.

5. The battery management system (BMS) (1) for a battery of claim 4, characterized by, It includes a microprocessor equipped with at least one memory that allows storage of at least one "Reefintegration" threshold variable and a stored detection voltage value Td. The memory also contains a program executed by the microprocessor that allows for the collection of voltage curve points, comparisons and decisions, and the implementation of equations that allow integration. The microprocessor receives a voltage V from the common point of the voltage divider bridge between resistors R1 and R2. global As input, measured values ​​are stored according to a determined frequency to observe the voltage curve V. global and the voltage curve V global The value is compared with the "Refintegration" value, and then when a "Refintegration" threshold crossover is detected, the threshold, defined by the value stored in the memory, triggers curve V. global Perform integration calculations and output the calculated integral curve (V) integ The value of ) is compared with the stored detection voltage value Td to activate the disconnection device to achieve disconnection.

6. The battery management system (BMS) (1) for a battery of claim 5, characterized by Said memory of said microprocessor also comprises the value of a stored "RapidThreshold" variable, in order to determine whether the calculation of the integral of said voltage curve V global requires taking into account a weighting coefficient, by comparing the variation dV of the voltage V global between two successive instants tl and t2 with "RapidThreshold".

7. The battery management system (BMS) (1) for a battery according to claim 6, characterized in that, The calculation of the integral comprises taking into account the "Slope and / or Ordinate" variable, wherein said microprocessor calculates said variable from the recorded voltage curve V global The data are calculated to obtain the "Slope and / or Ordinate" variable.

8. The battery management system (BMS) (1) for a battery of claim 4, characterized by, It comprises at least one comparator U1 ; a voltage divider bridge (R1, R2 or R9, R4) installed between the terminals of a modular assembly of said battery (4) or of a single element of said battery (4), which connects the input of the negative terminal of said comparator U1 to the common point of said resistors, to provide a voltage proportional to the voltage value V1 at the terminals of said battery by the ratio defined by the values of said two resistors (R1, R2 or R9, R4), and the positive terminal of said comparator being connected to a diode or to a power cell to define a reference voltage V2.

9. The battery management system (BMS) (1) for a battery of claim 8, characterized by, It comprises around said comparator U1 an integrator circuit comprising: - a resistor R5 connected between the common point of said voltage divider bridge R1, R2 and the negative input of said comparator U1 ; and - a resistor R8, capacitor C1 group installed in series by a common point, the other end of C1 being connected to the output of said comparator U1 and the other end of R8 connecting the common point of said two resistors R5, R8 and the negative input of U1, the values of R5 and C1 being adjusted to set the intervention time of the disconnection before the battery deteriorates when an overcurrent is detected.

10. The battery management system (BMS) (1) for a battery of claim 9, characterized by, The diode D2 is connected in parallel with the resistor R5, the cathode of which is connected to the common point of the voltage divider bridge, to change the integration time constant of the integration circuit in the event of an overcurrent or short circuit.

11. The battery management system (BMS) (1) for a battery of claim 8, characterized by, If the input voltage applied to the negative terminal of the comparator U1 is greater than the value of the reference voltage V2, the comparator U1 has a voltage at its output, the value of which is indicative of the "non-conductive" state, if the input voltage applied to the negative terminal of the comparator U1 is less than the value of the reference voltage V2, the comparator U1 has a voltage at its output, the value of which is indicative of the "conductive" state.

12. The battery management system (BMS) (1) for a battery of claim 4, characterized by, The detection device (2) comprises a capacitor C3 installed in parallel with R2, which, in combination with R1, forms a filter to filter out high-frequency interference.

13. The battery management system (BMS) (1) for a battery of claim 8, characterized by, Connected in parallel with R9 is a series assembly consisting of the resistor R3, the diode D3 with cathode towards the positive terminal, and the Zener diode D4 with cathode towards the common point of the voltage divider bridge R9, R4, a capacitor C5 connecting the common point of the bridge R9, R4 to the negative terminal of the battery (4) or of the modular assembly of cells or individual elements.

14. The battery management system (BMS) (1) for a battery of claim 8, characterized by, The hysteresis comparator circuit U2 with hysteresis, provided downstream of the comparator circuit U1, comprises a hysteresis assembly around the hysteresis comparator U2, which receives at the input of its negative terminal the voltage value of the output of the comparator U1.

15. The battery management system (BMS) (1) for a battery of claim 14, characterized by, The hysteresis comparator U2 comprises resistors R3, R4, installed as a voltage divider bridge between the positive and negative terminals of the battery (4), and whose common point with R3 and R4 connects the positive input of the hysteresis comparator U2, and also comprises a resistor R6, which connects the output of U2 to its positive input to define the threshold and hysteresis of the hysteresis comparator circuit comprising the hysteresis comparator U2.

16. The battery management system (BMS) (1) for a battery of claim 8, characterized by, The detection device (2) comprises a resistor R7, which, during normal operation, is connected in the forward direction to the positive terminal of the battery (4), in series with the diode D1; and a capacitor C2, which is connected on the one hand to the cathode of the diode and on the other hand to the negative terminal of the battery (4), so that it is possible to charge the battery during normal operation; the common point of D1 and C2, to which the supply input of the comparator U1 and of the hysteresis comparator U2 is connected, is used to maintain the power supply of the comparator U1 and / or of the hysteresis comparator U2 in the event of a collapse of the voltage of the battery (4) after a short circuit, to allow the activation of the disconnection.

17. The battery management system (BMS) (1) for a battery of claim 16, characterized by The reference voltage V2 of the positive input of the comparator U1 is provided by the Zener diode D2, which is connected by the resistor R1 to the common point of D1 and C2, the cathode of the Zener diode D2 also being connected to the negative terminal of the battery (4) or of the modular assembly of elements by the capacitor C1.

18. The battery management system (BMS) (1) for a battery of claim 16, characterized by, The hysteresis comparator U2 comprises a capacitor (C4, C3) connected in parallel with the resistor R4, which, in combination with another resistor (R3, R2), forms a filter to filter out high-frequency interference and to set a minimum trip time.

19. The battery management system (BMS) (1) for a battery of claim 16, characterized by, The positive input of the hysteresis comparator U2 is connected by the resistor R2 to the common point of R3, R9 and R7.

20. The battery management system (BMS) (1) for a battery of claim 8, characterized by, The detection device (2) comprises a flip-flop connected to the output of U1 or U2 for storing each action of the detection device (2) after each detection of deep discharge, overcurrent discharge and short-circuit discharge.

21. The battery management system (BMS) (1) for a battery of claim 4, characterized by, The disconnection device (3) comprises a switching device (30), wherein A first MOSFET M1 has its source connected to the negative terminal of a group of individual elements, its gate receives a voltage source driving M1, said source providing a selected voltage to make M1 conductive, a Zener diode D3, connected in reverse between the gate and the source of M1, a capacitor C2 protecting the gate of the MOSFET from excessive or high frequency voltages, and a Zener diode D1, connected in reverse between the gate and the drain of M1, a resistor R3 and a diode D2 limiting the switching speed of M1 in the positive direction from drain to gate, and a circuit consisting of a Schottky diode D4, connected in reverse to the drain of M1, in series with a capacitor C1 and a resistor R1 connected to the positive terminal of the battery (4) to limit the overvoltage when opening M1, said Schottky diode D4 having a fixed resistor I1 connected in parallel, connected on the one hand to the cathode of said diode and on the other hand to the drain of a second MOSFET M2, the source of said second MOSFET M2 being connected to the anode of said Schottky diode D4, the gate of M2 being controlled by the output of said detection circuit to prevent the load.

22. The battery management system (BMS) (1) for a battery of claim 4, characterized by, The disconnection device (3) comprises a second switching device (31), wherein A first MOSFET M1 has its source connected to the negative terminal of a group of individual elements, its gate receives a voltage source driving M1, said source providing a selected voltage to make M1 conductive, a circuit consisting of a Schottky diode D4, connected in reverse to the drain of M1, in series with a capacitor C1 and a resistor R1 connected to the positive terminal of the battery (4) to limit the overvoltage when opening M1, said Schottky diode D4 having a fixed resistor I1 connected in parallel, connected on the one hand to the cathode of said diode and on the other hand to the drain of a second MOSFET M2, the source of said second MOSFET M2 being connected to the anode of said Schottky diode D4, the gate of M2 being connected to the positive terminal of said group of individual elements, a Zener diode D6 and a resistor R6, connected in series with the gate of M2, said Zener diode D6 being connected in forward direction between said drain-gate direction, a Zener diode D5, connected between the gate and the source of M2, defining with said Zener diode D6 the voltage value at the gate of M2 and when M2 is conductive, a capacitor C5, connected between the gate and the source of M2 and in parallel with said Zener diode D5 to protect the gate of M2 from high frequency voltages, an optocoupler OP1, connected between the gate and the source of M2 and in parallel with said capacitor C5 to block M2 when the voltage or the temperature of the elements of a group of individual elements is exceeded, then the MOSFET M2 cuts off the charging current.

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