CIRCUIT BREAKER CONTROL CIRCUIT FOR BATTERY ACCUMULATOR MANAGEMENT SYSTEM AND BATTERY ACCUMULATOR MANAGEMENT SYSTEM EQUIPPED WITH SUCH A CIRCUIT

Abstract

The invention relates to a control circuit (5) for a disconnection device for a battery accumulator management system (3), characterized in that said control circuit (5) comprises: – an integration stage (9) configured to integrate the variation of a voltage (V'BAT) which is a voltage proportional to the voltage (VBAT) measured at the terminals of a battery (1); – a comparison stage (11) configured to compare the output voltage VAO1 of the integration stage (9) with a reference voltage VB, the output of said comparison stage (9) being configured to be connected to a battery disconnection device;characterized in that said device (5) comprises an element (RTH) varying an electrical quantity of said integration stage or of the comparison stage (11) as a function of the temperature, the comparison stage (11) being configured to emit at output a signal triggering the disconnection device, the duration before emission of said signal being a function of the temperature of said element (RTH). Figure to be published with the abstract: [Fig. 2];

Description

Title of the invention: CIRCUIT BREAKER CONTROL CIRCUIT FOR BATTERY MANAGEMENT SYSTEM BATTERY MULATORS AND BATTERY ACCUMULATOR MANAGEMENT SYSTEM EQUIPPED WITH SUCH A CIRCUIT

[0001] The technical context of the present invention is that of electric batteries, and in particular batteries with high electric current, in particular greater than 50 A, and preferably greater than 500 A, for example for aeronautical and / or aerospace applications. More particularly, the invention relates to a disconnection control circuit for a system for managing such batteries.

[0002] A battery generally comprises several battery modules forming an assembly which can also be connected to an external bus allowing data to be sent to a monitoring system, a system generally referred to as a battery accumulator management system (or “Battery Management System” in English).

[0003] The battery accumulator management system is notably configured to measure various physical quantities relating to the battery, and to the battery modules, such as voltages, currents, temperatures, internal resistances, etc., but also includes protection circuits to prevent the battery from operating under abnormal operating conditions, conditions which may damage the battery and cause human and / or material damage.

[0004] Abnormal operating conditions are generally understood to mean: overvoltages, overcurrents, undervoltages, excessively high battery temperature, short circuits, etc., i.e. all parameters which do not correspond to a nominal operating range of the battery.

[0005] The accumulator management systems thus comprise safety devices, such as a disconnecting device configured to cut the electrical connections of the battery with the outside (and therefore electrically isolate it) in the event that abnormal operating conditions occur.

[0006] Such circuit breaker devices are generally controlled by a control circuit, forming part of the management system, which monitors the values ​​of certain electrical quantities, for example the voltage at the terminals of the battery and which triggers the circuit breaker device if these electrical quantities take on values ​​corresponding to abnormal operating conditions.

[0007] Thus, when a battery is discharged under high current, for example at several hundred amperes, in particular due to a short circuit, the battery then rises in temperature. This high discharge current coupled with a high temperature can damage the battery, it is therefore necessary to activate the disconnection device when this combination of parameters occurs. Thus, as the temperature of the battery increases, it becomes all the more important that the electrical disconnection of the battery occurs quickly.

[0008] Furthermore, it is advantageous, when the battery has a temperature far from extreme values, to allow significant discharge intensities, for example temporary, without this triggering the electrical disconnection of the battery.

[0009] The present invention thus proposes to remedy at least one of the aforementioned drawbacks by proposing a new type of control circuit for a disconnection device for a battery accumulator management system, characterized in that said control circuit comprises at least: - an integration stage configured to integrate the variation of a voltage which is a voltage proportional to the voltage measured at the terminals of a battery; - a comparison stage configured to compare the output voltage of the integration stage to a reference voltage, the output of said comparison stage being configured to be connected to a battery disconnection device; characterized in that said circuit comprises an element varying an electrical quantity of the integration stage or of the comparison stage as a function of the temperature, the comparison stage being configured to emit at output a signal triggering the disconnection device, the duration before emission of said signal being a function of the temperature of said element.

[0010] Thus, the present control circuit according to the invention controls the activation of a disconnection device as a function of the temperature, for example of the battery, of at least one battery cell or of an electronic component in which a current intended for or originating from the battery circulates, this makes it possible in particular to stop the use of the battery as a function of its temperature, in particular when its temperature becomes too high with regard to a charge and / or discharge current, thus limiting the risks of deterioration of the battery during an abusive test or in abusive temperature, thus prolonging the service life of said battery equipped with such a disconnection control circuit.

[0011] According to a possible characteristic, said element varying an electrical quantity of said integration stage or of said comparison stage as a function of the temperature is an RTH thermistor. Said element is advantageously a passive element, such as a thermistor, to limit the electrical consumption of the control circuit, while being a solution easy to integrate, inexpensive and robust.

[0012] According to another possible characteristic, said thermistor is a thermistor with a negative temperature coefficient. Advantageously, the value of the thermistor is a function of the temperature of the battery, at least one battery cell or an electronic component in which a current intended for or originating from the battery flows. This thermistor is therefore advantageously thermally coupled with the battery, a cell or an electronic component, or even in thermal contact. The thermistor is, for example, thermally coupled to one of the aforementioned elements via a probe located at the heart of the battery (in the middle of the accumulators or cells).

[0013] According to another possible characteristic, said integration stage comprises at least one operational amplifier, called the first operational amplifier, mounted as a comparator-integrator, associated with a capacitor and at least one resistor, called the third resistor, said operational amplifier comprising: an inverting input supplied by a voltage proportional to the voltage measured at the terminals of a battery, a non-inverting input supplied by a reference voltage, and an output delivering an output voltage supplying the input of the comparison stage. Such a comparator-integrator assembly is advantageously configured to integrate the variation of a signal supplying one of its inputs, only when this signal takes a value greater than the value of the reference voltage.

[0014] According to another possible characteristic, the inverting input of the first operational amplifier is supplied by a voltage proportional to the voltage measured at the terminals of a battery via a thermistor.

[0015] According to another possible characteristic, said comparison stage comprises an operational amplifier, called the second amplifier, mounted as a comparator and associated with said element varying an electrical input quantity of said comparison stage as a function of the temperature.

[0016] According to another possible characteristic, said comparison stage is supplied, at the input, by a voltage proportional to the battery voltage and by the output voltage of the integration stage.

[0017] According to another possible characteristic, said comparison stage comprises a divider bridge comprising said thermistor and supplied by a voltage proportional to the battery voltage.

[0018] According to another possible characteristic, the operational amplifier of the comparison stage thus has an inverting input and a non-inverting input, the inverting input being connected to the divider bridge comprising said thermistor, while the non-inverting input is connected to the output of the integration stage, in particular the output of the first operational amplifier and to the output of the second amplifier. operational.

[0019] According to another possible characteristic, said circuit comprises an input stage configured to be connected, at input, to the terminals of a battery (of at least one cell or of an electronic component in which a current intended for or originating from the battery circulates) and the output voltage of which is the input voltage of said integration stage.

[0020] According to another possible characteristic, said input stage comprises at least two resistors, called respectively first resistor and second resistor, forming a circuit of the divider bridge type, the output voltage of said input stage corresponding to the voltage across the terminals of the foot resistor of said divider bridge.

[0021] According to another possible characteristic, the second operational amplifier has two inputs, an inverting input and a non-inverting input, the inverting input being connected to the divider bridge comprising the thermistor, and the non-inverting input being connected to the output of the integration stage and to the output of the second operational amplifier.

[0022] According to another possible characteristic, the divider bridge of the comparison stage is supplied by a direct voltage (which is for example an image of the battery voltage).

[0023] The invention also relates to a system for managing battery accumulators, characterized in that said management system comprises a control circuit as defined above.

[0024] The invention further relates to an electric battery, characterized in that said battery comprises a battery accumulator management system as defined above.

[0025] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several exemplary embodiments given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which: - [Fig.l] illustrates a very schematic view of an electric battery equipped with a battery accumulator management system according to the invention; - [Fig.2] illustrates a schematic view of a trip control circuit for the management system of [Fig.l]; - [Fig.3] is a comparative table of the times before disconnection as a function of the temperature between a control circuit of [Fig.2] and a circuit of the prior art; - [Fig.4] illustrates a schematic and partial view of an alternative embodiment of the control circuit of [Fig.2].

[0026] Of course, the characteristics, variants and different embodiments of the invention can be associated with each other, according to various combinations, to the extent that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of characteristics described below in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0027] In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

[0028] In the figures, the elements common to several figures retain the same reference.

[0029] [Fig.l] illustrates a very schematic and functional view of an electric battery 1, for example a lithium-ion battery, advantageously intended for aeronautical or aerospace applications, which comprises battery accumulators 2, or cells, a battery accumulator management system 3 connected to said accumulators 2, system 3 also designated by the English acronym “BMS” for “Battery Management System”, as well as a communication circuit 4 connected to said system 3 and configured to allow the system 3 to exchange information with the outside (information relating to the environment, the battery, the aircraft, etc.), for example with a computer, a server, a sensor, etc.

[0030] Said management system 3 is generally integrated into said battery 1, in order to monitor the various physical and / or electrical quantities characteristic of a battery 1 and / or its accumulators 2, for example a voltage, an internal resistance, etc.

[0031] Said management system 3 is also configured to prevent the operation of the battery 1 outside its nominal operating range, that is to say that the system 3 is configured to detect abnormal operating conditions of the battery 1 (or of its modules, or of at least one cell of the battery), such as an overcurrent, an overvoltage (in particular during its charging), an undervoltage (in particular during its discharging), an overheating, etc.

[0032] Such a system 3 may also comprise a locking circuit (not shown) configured to prevent the use of the battery 1, and therefore its operation, in particular if an abnormal operating condition is detected by the management system 3.

[0033] Thus, [Fig.2] illustrates a schematic and partial view of an electronic control circuit 5 of the disconnection device (not shown), circuit 5 for example integrated in the management system 3. It will be noted that the activation of the disconnection device causes the electrical disconnection of the battery 1, in order to protect it from possible damage. The disconnection device is for example an electro- mechanical or semiconductor.

[0034] The electronic control circuit 5 thus comprises: - an input stage 7 configured to be connected, at the input, to the terminals of the battery 1 and delivering at the output a voltage V'bat which is the image of the voltage at the terminals of said battery 1; - an integration stage 9 configured to receive as input the output voltage V'bat from the input stage 7 and a reference voltage VREF and deliver as output an output voltage VAoi; - a comparison stage 11 configured to receive and compare the output voltage VAoi of the integration stage 9 and a threshold voltage Vs, the output of said comparison stage 11 being configured to be connected to the battery disconnection device.

[0035] Said input stage 7 comprises for example at least two resistors Ri and R2, respectively called first resistor and second resistor, forming a circuit of the divider bridge type, the output voltage V^Aid of said input stage 7 corresponding to the voltage across the terminals of the foot resistor R2 of said divider bridge.

[0036] Thus, the output voltage V'bat of the input stage depends on the battery voltage and the values ​​of the first and second resistors Ri and R2, in the form: BAT ~ VBATR^R2

[0037] Said integration stage 9, for its part, comprises at least one operational amplifier AOi, called the first operational amplifier, mounted as a comparator-integrator (or also designated by the term proportional-integral assembly), associated with a capacitor Ci, called the first capacitor, and at least two resistors R3 and R4, called respectively the third resistor and the fourth resistor.

[0038] More particularly, the first operational amplifier AOi has an inverting input and a non-inverting input and an output, the non-inverting input being supplied by a reference voltage VREF.

[0039] The inverting input of said first operational amplifier AOi is connected, on the one hand, to the divider bridge of the input stage 7 via the third resistor R3, and, on the other hand, to the output of the first operational amplifier AOi via the first capacitor Ci in series with a resistor R4, called the fourth resistor.

[0040] Furthermore, advantageously, said integration stage 9 comprises a diode Di in parallel with the third resistor R3. Said diode Di is for example a PN junction diode, the anode of said diode Di being connected to the inverting input of the first operational amplifier AOi, while the cathode of said diode Di is connected to the input of the integration stage 9 (or to the first, second and third resistors).

[0041] Said comparison stage 11, for its part, comprises: - an operational amplifier AO2, called the second operational amplifier, mounted as a comparator in association with at least two resistors R5, R6, called respectively the fifth resistor and the sixth resistor; - a resistive divider bridge comprising at least three resistors RTH, R7, R8 supplied by a voltage VB (for example proportional to the battery voltage VBat) and delivering an output voltage Vs, called the trigger voltage.

[0042] More particularly, the resistive divider bridge of said integration stage comprises a thermistor RTH in parallel with the seventh resistor R7, the assembly arranged in series with the eighth resistor R8. Said RTH thermistor is advantageously a thermistor with a negative temperature coefficient, the value of its resistance decreasing when the temperature increases, in particular the temperature of the battery or of an electronic component in which an electric current intended for or coming from the battery circulates, such as a transistor. Said RTH thermistor has, for example, a resistance value of the order of a megohm at 25°C, in order to minimize the electrical consumption of the circuit, and to avoid the presence of a static current.

[0043] The second operational amplifier AO2 therefore has an inverting input and a non-inverting input, the inverting input being connected to the divider bridge comprising said thermistor RTH, while the non-inverting input is connected to the output of the integration stage 9, in particular the output of the first operational amplifier AOi, via the fifth resistor R5, as well as to the output of the second operational amplifier AO2 via the sixth resistor r6.

[0044] The second operational amplifier AO2 is therefore supplied by the output voltage VAoi of the integration stage 9 and by the output voltage VAo2 at the non-inverting input, while the inverting input is supplied by the threshold voltage Vs from the resistive divider bridge comprising the thermistor RTH.

[0045] The second operational amplifier AO2, and by extension the comparison stage 11, is therefore configured to: - deliver an output voltage corresponding to the saturation voltage -VSat when the value of the voltage VAoi at the non-inverting input is lower than a first threshold value VSi; - deliver an output voltage corresponding to the saturation voltage +VSat when the value of the voltage VAoi at the non-inverting input is greater than a first threshold value VSi.

[0046] In addition, the second operational amplifier AO2 again outputs a saturation voltage -VSat when the voltage value the value of the voltage VAoi at the non-inverting input is lower than a second threshold value VS2-Thus, the output voltage VAo2 of the comparison stage 11 can therefore take two extreme values, which are -VSAT and +VSAT, and when the output voltage VA02 is equal to +VSAT, there is then activation (or triggering) of the battery 1 disconnection device.

[0047] The threshold values ​​of VS1 and VS2 of the comparator assembly are thus functions (or depend) on an element varying an electrical quantity of said comparison stage as a function of the temperature, here the thermistor RTH of the divider bridge which supplies voltage to the non-inverting input of the second operational amplifier AO2.

[0048] The second amplifier AO2 is therefore advantageously a hysteresis comparator whose thresholds are compatible with the activation of the disconnection device.

[0049] Thus, in the event of an overcurrent at the terminals of the battery 1, there is a voltage drop, for example from 26 V to 14 V, this variation in the voltage VBAt is thus passed on by the input stage 7 in the form of a voltage V'BAt, which is a voltage proportional to the voltage VBAT, and integrated by the integration stage 9 which delivers an output voltage VAOi which increases as a function of time, from 0 V up to a maximum voltage value corresponding to the saturation voltage of the operational amplifier AOp

[0050] Then, when the output voltage VAOi of the integration stage 9 exceeds the first threshold value VS1, the output voltage VA02 of the comparison stage 11 switches to a value, here +VSAT, which triggers the disconnection device and causes the electrical isolation of the battery 1.

[0051] The time before tripping therefore depends on the value of the threshold voltage VS1 which is a function of the trigger voltage Vs at the inverting input of the second operational amplifier AO2, and by extension of the value of the thermistor Rth.

[0052] Thus, when the temperature increases, the value of the resistance RTH decreases, and therefore lowers the value of the threshold voltage VS1, thus causing a reduction in the time before the output voltage VA02 of the comparison stage 11 changes, and therefore there is activation of the disconnection device by the control circuit 5.

[0053] [Fig. 3] is a comparative table of the durations before tripping as a function of the temperature between a control circuit of [Fig. 2] and a circuit of the prior art. It can be seen that the duration before activation of the tripping device is variable, and now depends on the temperature, more particularly, the duration before tripping decreases when the temperature increases, thus making it possible to avoid the use of the battery when it heats up excessively, for example when charging or discharging the battery at high current.

[0054] In another variant embodiment of the invention not shown, the third resistor R3 is a thermistor, for example with a negative temperature coefficient, while the divider bridge delivering a voltage Vs to the inverting input of the second operational amplifier AO2 only comprises resistors (therefore no thermistor) forming a voltage divider bridge.

[0055] [Fig.4] illustrates another variant embodiment of the device 6 according to the invention in which only the comparison stage 11' has modifications compared to the embodiment illustrated in [Fig.2].

[0056] Indeed, the comparison stage 11' then comprises: - a first sub-stage 1 supplied it at the input by the output voltage VAoi of the integration stage 9 and configured to deliver at the output a voltage V'Ao2; - a second sub-stage 1 l'b supplied at the input by the output voltage V'A02 of the first sub-stage ll'a.

[0057] More particularly, the first sub-stage 11a comprises an operational amplifier OA'2 mounted as a comparator, for example an inverter. Said operational amplifier OA'2 has an inverting input, a non-inverting input, as well as an output, corresponding to the output of the first sub-stage 11a, which is connected to the second sub-stage 11b.

[0058] The inverting input of said operational amplifier OA'2 is connected to the output of the integration stage 9, while the non-inverting input is supplied by a reference voltage VB, for example via two resistors R9 and R10, called respectively the ninth and tenth resistors, forming a voltage divider bridge.

[0059] More particularly, the second sub-stage 1 l'b comprises a D-type flip-flop, D flip-flop, referenced BD, which is a flip-flop comprising: - a data input D connected to a reference voltage Vref; - a CLK clock input connected to the output of the first sub-stage 1 has: - an output Q connected to a diode D2, called the second diode, a resistor Rn, called the eleventh resistor, and a capacitor C2, called the second capacitor.

[0060] The flip-flop BD also includes a reset input CLR of the clock CLR, itself connected to the second diode D2, to the eleventh resistor Ru, and to the second capacitor C2.

[0061] Thus, the eleventh resistor Ru and the second capacitor C2 form a series RC circuit, while the second diode D2 is connected in parallel with the eleventh resistor Ru (the second diode D2 is therefore in series with the second capacitor C2)•

[0062] The value of input D is copied to output Q as long as the clock input is powered by a voltage V'A02, i.e. output Q emits a signal, for example a voltage VQ, triggering the disconnection of the disconnection device of the management system 3, in particular because the temperature of the thermistor, and by extension of the battery, is too high.

[0063] The series RC circuit, composed of the eleventh resistor Rn and the second capacitor C2, makes it possible to delay the resetting to zero (at the CLK input) of the BD flip-flop, i.e. to stop the emission of a VQ signal (at the Q output) triggering the circuit breaker device.

[0064] This reset is advantageously several tens of seconds, for example at least 60 seconds, or even at least 90 seconds, in order to allow time for the battery (and / or an electronic component of the battery) to drop in temperature.

[0065] The second diode D2, for its part, makes it possible to avoid a progressive rise in the voltage at the output Q of the flip-flop BD, so as soon as an adequate voltage V'Aoi is applied to the clock input, the voltage at the output Q changes (very quickly) to the expected value in order to trigger the circuit breaker device.

[0066] [Fig.5] illustrates a very schematic and partial view of a battery 1 comprising several accumulators 2, or cells, mounted in series and in parallel.

[0067] Said battery 1, or the accumulator management system of said battery 1, then advantageously comprises one or more control circuits 5 according to the invention. More particularly, each equipotential line of cells 2 is connected to a control circuit 5, that is to say that at least one control circuit 5 is connected to the terminals of the cells having identical (or very close) voltage values, and a control circuit 5 is also connected to the terminals of all of said cells.

[0068] Thus, if one of the cells of an equipotential line or one of the cells of the battery presents an excessive temperature during a charge or a discharge at high current intensity, one of the control circuits 5 is configured to detect it and send a signal to a disconnection device, triggering the disconnection of said battery 1.

[0069] It will be noted that the control circuits connected to an equipotential line of cells 2 can be a control circuit of the prior art (therefore without thermistor), while the control circuit 5 connected to the terminals of all the cells 2 forming battery 1 is necessarily a control circuit 5 according to the invention.

Claims

Claims

1. Control circuit (5) of a disconnection device for a management system (3) of battery accumulators, characterized in that said control circuit (5) comprises: - an integration stage (9) configured to integrate the variation of a voltage (V'bat) which is a voltage proportional to the voltage (VBat) measured at the terminals of a battery (1); - a comparison stage (11) configured to compare the output voltage VAoi of the integration stage (9) with a reference voltage Vc, the output of said comparison stage (9) being configured to be connected to a battery disconnection device;characterized in that said device (5) comprises an element (RTH) varying an electrical quantity of the integration stage (9) or of the comparison stage (11) as a function of the temperature, the comparison stage (11) being configured to emit at output a signal triggering the disconnection device, the duration before emission of said signal being a function of the temperature of said element (RTH).;

2. Control circuit (5) according to the preceding claim, characterized in that said element varying an electrical quantity of said integration stage (9) or of said comparison stage (11, 11') as a function of the temperature is a thermistor (RTH).

3. Control circuit (5) according to the preceding claim, characterized in that said thermistor (RTH) is a thermistor with a negative temperature coefficient.

4. Control circuit (5) according to any one of claims 2 to 3, characterized in that said comparison stage (11) comprises a divider bridge comprising said thermistor (RTh)-

5. Control circuit (5) according to any one of the preceding claims, characterized in that said comparison stage (11) is supplied, at the input, by a voltage proportional (VB) to the battery voltage (VBat) and the output voltage (VAoi) of the integration stage (9).

6. Control circuit (5) according to any one of the preceding claims, characterized in that said comparison stage (11) comprises an operational amplifier (AO2), called second operational amplifier, mounted as a comparator, and associated with said element (R TH) varying an electrical quantity of said comparison stage (11) as a function of the temperature.

7. Control circuit (5) according to the preceding claim, characterized in that the second operational amplifier (AO2) has two inputs, an inverting input and a non-inverting input, the inverting input being connected to the divider bridge comprising said element (RTH), and the non-inverting input being connected to the output of the integration stage (9) and to the output of the second operational amplifier (AO2).

8. Control circuit (5) according to any one of the preceding claims, characterized in that said integration stage (9) comprises at least one operational amplifier (AOi), called the first operational amplifier, mounted as a comparator-integrator, associated with a capacitor (Ci) and at least one resistor (R3), called the third resistor and, said operational amplifier (AOi) comprising: an inverting input supplied by a voltage proportional (V'bat) to the voltage measured at the terminals of a battery (1), a non-inverting input of said operational amplifier (AOi) supplied by a reference voltage (VREF), and an output delivering an output voltage (Vaoi) supplying the input of the comparison stage (11, 11').

9. Control circuit (5) according to the preceding claim, characterized in that the inverting input of the first operational amplifier (AO i) is supplied by a voltage proportional (V'bat) to the measured voltage (VBat) at the terminals of a battery via a thermistor (R3).

10. Management system (3) for battery accumulators, characterized in that said management system (3) comprises a control circuit (5) according to any one of the preceding claims.

11. Electric battery (1), characterized in that said battery comprises a management system (3) of the battery accumulators according to the preceding claim.