BATTERY CHARGING CURRENT REGULATION DEVICE AND BATTERY CELL MANAGEMENT SYSTEM INCLUDING SUCH A DEVICE

Abstract

The invention relates to a charging current regulation device (6) for a battery (1), said device being a four-terminal network configured to connect a battery to a charging device (8), said device (6) comprising at least a first transistor (M1), referred to as the charging transistor, and a thermistor (R1) which are configured to regulate, in conjunction, the charging current of the battery (1) as a function of temperature. Figure to be published with the abstract: [Fig. 2]

Description

Title of the invention: BATTERY CHARGING CURRENT REGULATION DEVICE AND SYSTEM BATTERY CELL MANAGEMENT INCLUDING SUCH A DEVICE

[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.

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

[0003] The battery accumulator management system is specifically configured to measure various physical quantities relating to the battery and 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 can damage the battery and cause human and / or material damage.

[0004] Abnormal operating conditions generally mean: overvoltages, overcurrents, undervoltages, excessively high battery temperature, short circuits, etc., that is to say, all parameters not corresponding to a nominal operating range of the battery.

[0005] Battery management systems thus include safety devices, such as a circuit breaker configured to cut off the battery's electrical connections with the outside (and thus isolate it electrically) in the event of abnormal operating conditions.

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

[0007] A battery, for example Lithium-Ion, intended for aeronautical applications and / or aerospace applications can exhibit voltages ranging from a few tens of volts to over a thousand volts, with discharge currents between ten and one hundreds of amps.

[0008] Such batteries naturally comprise several cells, or accumulators, arranged in series and in parallel; for example, eight 3.3-volt cells can be connected in series as illustrated in [Fig. 1]. The sum of this series of battery cells generates an overall voltage of approximately 26.4 V.

[0009] Thus, when recharging these batteries, and more specifically the battery cells, it is necessary to supply them with a specific current, for example 5 A, for the time required to fully recharge said battery cells. This recharging operation is generally carried out by means of a device or circuit that regulates the charging current delivered to the battery being charged.

[0010] Unfortunately, prior art devices or circuits have electronic components whose temperature rise (or overheating) causes a variation in the charging current that exceeds an permissible and / or battery protection value. Furthermore, prior art devices or circuits may also exhibit charging current overshoots at the start of battery charging (for example, on the order of several tens of amperes for 2 seconds), and / or have an average charging current value well below a desired target value.

[0011] The present invention thus aims to remedy at least one of the aforementioned drawbacks by proposing a new type of device for regulating a charging current for a battery, said device being a four-terminal network configured to connect a battery to be charged to a charging device, said device comprising at least a first transistor, called a charging transistor, and a thermistor which are configured to regulate, in association, the charging current of the battery as a function of temperature.

[0012] The present charging current regulation device for charging a battery, or one or more battery cells, is an inexpensive, robust solution, easy to integrate into a battery accumulator management system, while allowing better regulation and / or stability of this charging current, depending on the temperature, in particular the temperature rise of the charging transistor.

[0013] According to one possible characteristic, said first transistor is configured to operate in linear mode. Using the load transistor in linear mode allows in particular to improve the control (or regulation) of the value of the load current, in particular because the heat generated by the transistor associated with a thermistor allows self-regulation.

[0014] According to another possible feature, the thermistor is thermally coupled with the first transistor. Advantageously, the trace on which the first transistor is soldered is thermally coupled to the thermistor so as to be heated via the trace.

[0015] According to another possible feature, said device comprises a second transistor, called a regulating transistor, the second transistor being configured to force the first transistor to operate in linear mode. Advantageously, a regulating transistor participates in regulating the voltage across the load transistor to maintain the latter in a linear operating regime.

[0016] According to another possible characteristic, the first transistor is a field-effect transistor, and the second transistor is an NPN type transistor.

[0017] According to another possible feature, said charging transistor has a gate, a drain and a source, said source being configured to be connected to the positive terminal of the charging device and to the positive terminal of the battery to be charged, said gate being configured to be connected to the negative terminal of the charging device.

[0018] According to another possible feature, the transistor source is configured to be connected to the positive terminal of the load device via at least one diode and / or a resistor.

[0019] According to another possible feature, the regulating transistor has a base, an emitter and a collector, the collector of the regulating transistor being connected to the source of the load transistor, the base of the regulating transistor being connected to the gate of the load transistor.

[0020] According to another possible feature, the regulating transistor is mounted in parallel with the load transistor, that is to say, the base and collector of the regulating transistor are mounted in parallel with the gate and source of the load transistor.

[0021] According to another possible feature, the base of the regulating transistor is connected to the gate of the load transistor via a resistor, called the third resistor.

[0022] According to another possible feature, the device includes a diode, called the second diode, and a resistor, called the second resistor, each being mounted in parallel with respect to each other, but also the load transistor and / or the regulating transistor.

[0023] According to another possible feature, the second diode is connected to the source and gate of the load transistor and / or connected to the collector and base of the regulating transistor.

[0024] According to another possible feature, the base and emitter of the regulating transistor and the source of the charging transistor are configured to be connected to the negative terminal of the battery to be charged.

[0025] According to another possible characteristic, the base of the regulating transistor and the The charging transistor's power supply is configured to be connected to the negative terminal of the battery being charged via a resistor, known as the fourth resistor. This fourth resistor helps to limit the maximum charging current.

[0026] According to another possible characteristic, said thermistor is of the negative temperature coefficient type.

[0027] The invention also relates to a battery accumulator management system, characterized in that said management system comprises a control circuit as defined above.

[0028] The invention further relates to an electric battery, characterized in that said battery comprises a battery accumulator management system as defined above.

[0029] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given by reference to the accompanying schematic drawings on the other hand, in which: - Fig. 1 illustrates a very schematic and functional view of an electric battery equipped with a battery accumulator management system according to the invention; - Fig. 2 illustrates a schematic view of a battery charging current regulation device for the management system of Fig. 1.

[0030] Of course, the features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0031] In particular, all the variants and embodiments described are combinable with each other provided there are no technical obstacles to such combination. In the figures, elements common to several figures retain the same reference numeral.

[0032] Figure 1 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 cells 2, a battery management system 3 connected to said cells 2, system 3 also designated by the English acronym "BMS" for "Battery Management System", as well as a communication circuit 4 connected to said management system 3 and configured to exchange information with the outside (information relating to the environment, the battery, the aircraft, etc.)

[0033] Said management system 3 is generally integrated into said battery 1, in order to monitor the various physical or electrical quantities characteristic of a battery 1 and / or its accumulators 2, for example a voltage, an internal resistance, etc.

[0034] Said management system 3 is also configured to prevent the battery 1 from operating outside its nominal operating range, i.e. the system is configured to detect abnormal operating conditions of the battery (or its modules), such as overcurrent, overvoltage (especially during charging), undervoltage (especially during discharging), overheating, etc.

[0035] Such a system 3 may also include other circuits and / or devices in particular for regulating the charging current to a battery, or to one or more battery cells.

[0036] Fig. 2 illustrates a very schematic and functional view of a regulation device 6 for a charging current for one or more battery cells 2, said device 6 being a four-pole configured to connect the battery cell(s) 2 to be charged to a charging device 8, such as an alternator, another battery, a charger, etc.

[0037] Said device 6 is therefore connected, on the one hand, to the terminals of the cell(s) 2 of the battery, and on the other hand to the terminals of the charging device 8. Furthermore, device 6 comprises at least: - at least one transistor Mb called a load transistor, configured to operate in linear mode, said load transistor Mi being for example a field-effect transistor; - a thermistor Ri configured to regulate in association with the charging transistor Mi the charging current flowing from the charging device 8 to the battery cell(s) 2 as a function of temperature.

[0038] The thermistor Ri is advantageously a thermistor with a negative temperature coefficient and is thermally coupled with the load transistor Mb. The thermistor Ri therefore exhibits a decrease in its resistance with increasing temperature of the load transistor Mb, thus limiting, or even eliminating, the reduction in the charging current with increasing temperature of said transistor Mb.

[0039] Said device 6 advantageously includes another transistor Tb called a regulating transistor, which is a transistor configured to impose linear operation on the first transistor Mb. The regulating transistor Ti is, for example, an NPN (bipolar) type transistor.

[0040] Said load transistor Mi has a gate, a drain and a source, said source being configured to be connected to the positive terminal of the charging device 8 and to the positive terminal of the cell 2 to be charged, said grid being, in turn, configured to be connected to the negative terminal of the charging device 8.

[0041] Furthermore, device 6 includes a diode Db, referred to as the first diode. The source of the load transistor Mi is thus connected to the positive terminal of the load device 8 via the first diode Di and the thermistor Rb

[0042] Furthermore, the regulating transistor Ti has a base, an emitter and a collector, the collector of the regulating transistor Ti being connected to the source of the load transistor Mb and the base of the regulating transistor Ti being connected to the gate of the load transistor Mb. Thus, the regulating transistor Ti is mounted in parallel with the load transistor Mb respectively collector to source and base to gate.

[0043] The regulating transistor Ti thus participates in the regulation of the voltage at the gate-source terminals of the load transistor Mi in order to maintain the latter in a linear operating regime.

[0044] Furthermore, the base and emitter of the regulating transistor Ti and the source of the charging transistor Mi are configured to be connected to the negative terminal of the cell 2 to be charged.

[0045] Furthermore, advantageously, device 6 comprises: - a diode D2, called the second diode, connected to the source and gate of the load transistor Mi and connected to the collector and base of the regulating transistor Ti; - a resistor R2, called the second resistor, connected to the source and gate of the load transistor Mi and connected to the collector and base of the regulating transistor Ti (the second resistor R2 allows, among other things, for a zero voltage at the gate of the transistor Ml when the circuit is not conducting); - a resistor R3, called the third resistor, the base of the regulating transistor Ti is connected to the gate of the load transistor Mi via said third resistor R3; - a resistor R4, called the fourth resistor, the base of the regulating transistor Ti and the source of the load transistor Mi being configured to be connected to the negative terminal of cell 2 to be charged via the fourth resistor R4 (the fourth resistor allows, in particular, the adjustment of the gate potential of the load transistor Mi and thus allows self-regulation around the linear voltage of Mb).

[0046] It should also be noted that the first and second diodes Di and D2 form a diode divider, and that the first and second resistors Ri and R2 form a resistive divider, the resistance of which Ri allows the current of the load transistor Mi to be regulated as a function of the temperature of said transistor Mb

[0047] The second diode D2 and the second resistor are therefore connected in parallel with each other, but also with the load transistor Mi and the re- transistor gulation Th

[0048] It should also be noted that the first and second diodes Di and D2 are advantageously Zener diodes. Furthermore, the anode of the first diode Di is connected to the source of the load transistor Mb, while the cathode of the first diode Di is connected to the first resistor Rb. In addition, the anode of the second diode D2 is connected to the gate of the load transistor Mi and to the base of the regulating transistor Ti (notably via the third resistor R3), while the cathode of the second diode D2 is connected to the source of the load transistor Mi and to the collector of the regulating transistor Tb.

[0049] The second diode D2 also limits the voltage across the terminals of the load transistor Mb, in particular the voltage between the source and the gate of said transistor Mb. In addition, the association of the first and second diodes Di and D2 makes it possible to close the circuit when the load device 8 has a voltage lower than the sum of the voltages of diodes Di and D2, or when there is no load device 8 connected, thus limiting the electrical consumption of the device 6 when it is not in use.

[0050] In unrepresented embodiments of the invention, the regulating device 6 comprises: - an optocoupler, on the one hand, connected to the gate of the load transistor Mi and, on the other hand, intended to be connected to the negative terminal of the load device 8, and / or - a circuit breaker, such as a switch, a disconnecting device, a bistable relay, etc., on the one hand connected to the first resistance Rb and on the other hand, intended to be connected to the positive terminal of the charging device 8.

[0051] Said optocoupler and / or circuit breaker are thus configured to cut off the battery charge in case of an anomaly of voltage, current, temperature, etc., by opening the circuit between the charging device 8 and the regulating device 6.

Claims

Claims

1. Device for regulating a charging current (6) for a battery (1), said device being a quadrupole configured to connect a battery to a charging device (8), said device (6) comprising at least a first transistor (Mi), called charging transistor, and a thermistor (Ri) which are configured to regulate, in association, the charging current of the battery (1) as a function of the temperature.

2. Device (6) according to the preceding claim, characterized in that said first transistor (Ml) is configured to operate in linear mode.

3. Device (6) according to the preceding claim, characterized in that said device comprises a second transistor (TJ, called a regulation transistor, the second transistor (TJ being configured to impose linear operation on the first transistor (MJ.

4. Device (6) according to any one of the preceding claims, characterized in that said charging transistor (MJ) has a gate, a drain and a source, said source being configured to be connected to the positive terminal of the charging device (8) and to the positive terminal of the battery to be charged, said gate being configured to be connected to the negative terminal of the charging device (8).

5. Device (6) according to the preceding claim, characterized in that the source of the transistor is configured to be connected to the positive terminal of the charging device via the resistor (Ri) and at least one diode (Di).

6. Device (6) according to the preceding claim, characterized in that the regulation transistor (Ti) has a base, an emitter and a collector, the collector of the regulation transistor (Ti) being connected to the source of the load transistor (Mi), the base of the regulation transistor (Ti) being connected to the gate of the load transistor (MJ.

7. Device (6) according to the preceding claim, characterized in that the base of the regulation transistor (TJ) is connected to the gate of the load transistor (MJ) via a resistor (R3).

8. Device (6) according to the preceding claim, characterized in that the base and the emitter of the regulation transistor (TJ and the source of the charging transistor (MJ are configured to be connected to the negative terminal of the battery to be charged.

9. Device (6) according to the preceding claim, characterized in that the base of the regulation transistor (Ti) and the source of the charging transistor (MJ) are configured to be connected to the negative terminal of the battery to be charged via a resistor (R4).

10. Battery accumulator management system (3), characterized in that said management system (3) comprises a regulation device (6) 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.

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