A charging and discharging protection circuit, a lithium battery pack management system and a lithium battery pack

Abstract

This invention discloses a charge / discharge protection circuit, a lithium battery management system, and a lithium battery pack, applied to a lithium battery protection board. The charge / discharge protection circuit includes: a protection module connected in parallel to the charging MOSFET Q1; one end of the protection module is connected to an electrical load and a generator, and the other end of the electrical load and generator is connected to the positive terminal of the lithium battery; the other end of the protection module is connected to the negative terminal of the lithium battery through a discharging MOSFET Q2; the protection module includes a supercapacitor C100 connected in parallel to the charging MOSFET Q1; when the lithium battery is fully charged, the charging MOSFET Q1 is turned off, and the supercapacitor C100 is connected in series with the lithium battery to form a new battery pack, which is then connected in parallel to the generator to stabilize the generator's output voltage. This invention stabilizes the generator's output voltage and prevents voltage fluctuations caused by the generator floating after the lithium battery is fully charged.

Description

Technical Field

[0001] This invention relates to the field of lithium battery control technology, and in particular to a charge / discharge protection circuit, a lithium battery pack management system, and a lithium battery pack. Background Technology

[0002] After a lithium battery is fully charged, a typical charging control circuit usually shuts down the MOSFET Q1 to prevent overcharging. However, in this situation, the freewheeling current generated by the generator's inductor will cause the generator's output voltage to be significantly higher than the lithium battery's voltage, resulting in a voltage difference between the generator and the lithium battery. Since the generator is suspended outside the lithium battery and has no stable load to absorb electrical energy, this voltage difference will cause significant voltage fluctuations.

[0003] Voltage fluctuations have multifaceted effects on vehicle electrical systems, the most obvious being the flickering of car lights. This not only affects the driving experience but can also adversely impact other electronic devices in the vehicle. Therefore, effectively controlling the fluctuations in generator output voltage after a lithium battery is fully charged has become a pressing technical problem to be solved.

[0004] While existing solutions can alleviate voltage fluctuations to some extent, most suffer from drawbacks such as complex design, high cost, and unsatisfactory results. Therefore, developing an efficient and cost-effective technology to stabilize generator output voltage and prevent voltage fluctuations caused by generator levitation after a fully charged lithium battery is a pressing issue. Summary of the Invention

[0005] To overcome the above-mentioned technical problems, the present invention provides a charge and discharge protection circuit, a lithium battery management system, and a lithium battery pack, which stabilizes the output voltage of the generator and prevents voltage fluctuations caused by the generator floating after the lithium battery is fully charged.

[0006] In a first aspect, the present invention provides a charge and discharge protection circuit for use on a lithium battery protection board, wherein the protection board is provided with a charging MOSFET Q1 and a discharging MOSFET Q2 connected to the lithium battery.

[0007] The charge / discharge protection circuit includes:

[0008] A protection module is connected in parallel to the charging MOSFET Q1. One end of the protection module is used to connect the electrical load and the generator, and the other end of the electrical load and the generator is connected to the positive terminal of the lithium battery. The other end of the protection module is connected to the negative terminal of the lithium battery through the discharging MOSFET Q2.

[0009] The protection module includes a supercapacitor C100, which is connected in parallel with the charging MOSFET Q1;

[0010] When the lithium battery is fully charged, the charging MOSFET Q1 is turned off, and the supercapacitor C100 is connected in series with the lithium battery to form a new battery pack. The new battery pack is connected in parallel with the generator to stabilize the generator's output voltage.

[0011] In some embodiments, the positive terminal of the supercapacitor C100 is connected to the drain of the charging MOSFET Q1, and the negative terminal of the supercapacitor C100 is connected to the source of the charging MOSFET Q1.

[0012] In some embodiments, the protection module includes a discharge process delay unit, which includes a capacitor C101 and a resistor R100. The capacitor C101 is connected in parallel with the charging MOSFET Q1, and the resistor R100 is connected in series with the gate of the charging MOSFET Q1.

[0013] In some embodiments, one end of the capacitor C101 is connected to the gate of the charging MOSFET Q1, and the other end of the capacitor C101 is connected to the source of the charging MOSFET Q1.

[0014] In some embodiments, a control unit is also included, which is connected to the charging MOSFET Q1 via the resistor R100. The control unit is used to control the charging MOSFET Q1 to turn on or off according to the voltage state of the lithium battery.

[0015] In some embodiments, the capacitance of the farad capacitor C100 is 1 to 50 farads.

[0016] In some implementations, when the lithium battery needs to be charged, the charging MOSFET Q1 is turned on, and the supercapacitor C100 releases its charge through the charging MOSFET Q1.

[0017] In some implementations, the discharge process duration of the discharge process delay unit is 5ms to 20ms.

[0018] In a second aspect, the present invention provides a lithium battery pack management system, including the charge and discharge protection circuit as described in any of the preceding claims.

[0019] Thirdly, the present invention provides a lithium battery pack, including the lithium battery pack management system described above.

[0020] This invention provides a charge / discharge protection circuit, a lithium battery management system, and a lithium battery pack. The protection module effectively absorbs and stabilizes generator voltage fluctuations, ensuring stable voltage in the generator's suspended state after the lithium battery is fully charged. This reduces vehicle headlight flickering, protects the charging MOSFET and other sensitive electronic components from overvoltage damage, and extends component lifespan. After the lithium battery is fully charged, the generator output voltage remains stable, significantly reducing voltage fluctuations and enhancing the reliability of the entire circuit system. This design simplifies the circuit structure, reduces manufacturing and maintenance costs, and improves lithium battery charging efficiency, ensuring stable system operation under various operating conditions. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of the lithium battery protection board of the present invention;

[0022] Figure 2 This is a schematic diagram of voltage changes during the charging process of the lithium battery of the present invention;

[0023] Figure 3 This is the voltage waveform when the charging MOSFET Q1 is turned off, assuming there is no protection module. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] It should be noted that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0028] In the above description, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0029] like Figure 1 As shown, this application provides a charge and discharge protection circuit, which is applied in a lithium battery protection board. By setting a protection module, it absorbs the voltage fluctuations of the generator and prevents voltage fluctuations caused by the generator floating after the lithium battery is fully charged.

[0030] Specifically, this application is applied to a lithium battery protection board, which is provided with a charging MOSFET Q1 and a discharging MOSFET Q2 connected to the lithium battery; a protection module, which is connected in parallel to the charging MOSFET Q1, one end of the protection module is used to connect to the electrical load and the generator, and the other end of the electrical load and the generator is connected to the positive terminal of the lithium battery; the other end of the protection module is connected to the negative terminal of the lithium battery through the discharging MOSFET Q2.

[0031] When the lithium battery is fully charged, the charging MOSFET Q1 is turned off. When the generator voltage is higher than the lithium battery voltage, the protection module and the lithium battery are connected in series to form a new battery pack, which is then connected in parallel with the generator. The lithium battery and the protection module perform appropriate voltage distribution, absorb current surges, and balance the generator voltage to stabilize the generator's output voltage.

[0032] In this embodiment, the protection module includes a supercapacitor C100, which absorbs voltage surges. The supercapacitor C100 is connected in parallel to the charging MOSFET Q1. When MOSFET Q1 is turned off, the supercapacitor C100 is connected in series with the lithium battery to form a new battery pack. This new battery pack is connected in parallel with the generator to stabilize the generator's output voltage. The capacitance of the supercapacitor C100 can be reasonably set according to the capacity of the lithium battery and the generator to fully absorb voltage surges within the circuit. In this application, the supercapacitor C100 is 1 to 50 supercapacitors.

[0033] The voltage change across the supercapacitor C100 is as follows Figure 2 As shown. In the initial stage of charging, the generator begins to charge the lithium battery. The generator's output voltage gradually increases from the initial state as the lithium battery voltage increases, while the supercapacitor C100 is short-circuited by the charging MOSFET Q1, and its voltage remains zero.

[0034] When the lithium battery is fully charged, the charging MOSFET Q1 is turned off. The generator voltage is higher than the lithium battery voltage. However, because the charging MOSFET Q1 is turned off, the supercapacitor C100 is immediately connected in series with the lithium battery. The generator voltage does not directly act on the lithium battery. It is stabilized by the combination of the supercapacitor C100 and the lithium battery in series.

[0035] The supercapacitor C100 is connected in series with the lithium battery and continues to be connected in parallel with the generator. During this process, the voltage of the supercapacitor C100 undergoes a slow rise, and its voltage is equal to the generator voltage minus the lithium battery voltage. This absorbs and buffers fluctuations in the generator voltage. Subsequently, the generator voltage rises to its rated value, maintaining a stable voltage output and preventing voltage fluctuations from affecting the circuit.

[0036] Until the next charging cycle, when the lithium battery needs charging, the charging MOSFET Q1 will turn on. The positive terminal of the supercapacitor C100 is connected to the drain of the charging MOSFET Q1, and the negative terminal of the supercapacitor C100 is connected to the source of the MOSFET Q1. The voltage of the supercapacitor C100 is equal to the generator voltage minus the lithium battery voltage. When the lithium battery needs charging, the MOSFET Q1 is slowly turned on under the action of the discharge delay unit R100 and C101, and the supercapacitor C100 slowly releases its charge through the charging MOSFET Q1.

[0037] In this application, the new battery pack formed by the supercapacitor C100 connected in series with the lithium battery effectively absorbs and stabilizes the voltage fluctuations of the generator. When the lithium battery is fully charged, the generator voltage is higher than the lithium battery voltage, and the generator is suspended outside the lithium battery, resulting in large voltage fluctuations. The supercapacitor C100 responds quickly and smooths the voltage changes, preventing voltage surges from affecting the circuit. During the off-state of the charging MOSFET Q1, the supercapacitor C100 absorbs and stabilizes the surge voltage of the generator output, avoiding situations such as... Figure 3 The surge voltage shown can damage the charging MOSFET Q1 and the lithium battery, thus extending the lifespan of these components. This ensures the stable operation of the entire automotive electrical system under various conditions, preventing system failures or anomalies caused by voltage fluctuations and enhancing circuit reliability.

[0038] The introduction of the C100 farad capacitor effectively reduces reliance on complex circuit designs and additional electronic components, thereby simplifying circuit design and reducing manufacturing and maintenance costs. Since fluctuations in generator voltage can cause vehicle headlight flickering, the C100 farad capacitor ensures continued stability of the generator's output voltage even after the lithium battery is fully charged, significantly reducing this flickering phenomenon, improving driving safety and comfort, and significantly enhancing the stability and reliability of the generator and lithium battery, thus avoiding the negative impact of voltage fluctuations on the vehicle's electrical system.

[0039] Furthermore, this application includes a discharge process delay unit, comprising a capacitor C101 and a resistor R100. The capacitor C101 is connected in parallel with the charging MOSFET Q1; the resistor R100 is connected in series with the gate of the charging MOSFET Q1. One end of the capacitor C101 is connected to the gate of the charging MOSFET Q1, and the other end is connected to the source of the charging MOSFET Q1. The resistance value of the resistor R100 is greater than the conventional gate resistance value of a MOSFET. The parallel connection of the resistor R100 and the capacitor C101 forms a discharge process delay unit, allowing the gate voltage of the charging MOSFET Q1 to rise slowly, and the discharge current of the charging MOSFET Q1 to increase slowly. This prevents the supercapacitor C100 from causing excessive discharge current after the charging MOSFET Q1 is turned on, thus extending the service life of the supercapacitor C100.

[0040] Furthermore, this application also includes a control unit connected to the charging MOSFET Q1 via a resistor R100. The control unit is used to control the MOSFET Q1 to turn on or off based on the voltage state of the lithium battery. In a specific embodiment, the control unit may be a BMS chip, controlling the charging MOSFET Q1 to turn on or off according to the lithium battery's voltage state to ensure that the lithium battery is charged and discharged under appropriate conditions, maintaining the stability and reliability of the entire lithium battery system, reducing voltage fluctuations, and extending the lithium battery's lifespan.

[0041] When the control unit detects that the lithium battery voltage is lower than the set charging threshold, indicating that the lithium battery needs charging, the control unit sends a control signal to turn on the charging MOSFET Q1, allowing the generator voltage to charge the lithium battery through the charging MOSFET Q1. When the control unit detects that the lithium battery voltage reaches or exceeds the set charging cutoff threshold, indicating that the lithium battery is fully charged, the control unit sends a control signal to turn off the charging MOSFET Q1, stopping further charging of the lithium battery and preventing overcharging.

[0042] The control unit, i.e., the charging control terminal of the BMS chip, is connected to a resistor R100 (larger than a conventional resistor). A capacitor C101 is connected in parallel across the gate and source of the charging MOSFET Q1. This allows the charging MOSFET Q1 to turn on slowly, enabling the charge on the supercapacitor C100 to be released gradually through Q1, reducing the inrush current from the supercapacitor C100 to the charging MOSFET Q1. The discharge process can last from 5ms to 20ms.

[0043] When multiple lithium batteries are connected in series, the control unit can balance the voltage of each battery cell or manage the discharge process of the lithium battery. It controls the discharge MOSFET Q2 to regulate the discharge of the lithium battery to the load or circuit, preventing overcharging or over-discharging under certain circumstances. The control unit can communicate with external monitoring systems, such as Bluetooth modules, to provide status information of the lithium battery and system, facilitating remote monitoring and management, and providing necessary status feedback and communication functions.

[0044] Based on the same inventive concept, this application also provides a lithium battery pack management system, wherein the lithium battery protection board includes a charge and discharge protection circuit as described above.

[0045] Based on the same inventive concept, this application also provides a lithium battery pack, which includes the lithium battery pack management system described above.

[0046] This invention provides a charge / discharge protection circuit, a lithium battery management system, and a lithium battery pack. The protection module effectively absorbs and stabilizes generator voltage fluctuations, ensuring stable voltage in the generator's suspended state after the lithium battery is fully charged. This reduces vehicle headlight flickering and protects the charging MOSFET and other sensitive electronic components from overvoltage damage, extending component lifespan. After the lithium battery is fully charged, the generator output voltage remains stable, significantly reducing voltage fluctuations and enhancing the reliability of the entire circuit system. This design simplifies the circuit structure, reduces manufacturing and maintenance costs, and improves lithium battery charging efficiency, ensuring stable system operation under various operating conditions.

[0047] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A charge / discharge protection circuit, characterized in that, It is used in a lithium battery protection board, wherein the protection board is provided with a charging MOSFET Q1 and a discharging MOSFET Q2 connected to the lithium battery; The charge / discharge protection circuit includes: A protection module is connected in parallel with the charging MOSFET Q1. One end of the protection module is used to connect the electrical load and the generator, and the other end of the electrical load and the generator is connected to the positive terminal of the lithium battery. The other end of the protection module is connected to the negative terminal of the lithium battery through the discharging MOSFET Q2. The protection module includes a supercapacitor C100, which is connected in parallel with the charging MOSFET Q1. The protection module includes a discharge process delay unit, which includes a capacitor C101 and a resistor R100. One end of the capacitor C101 is connected to the gate of the charging MOSFET Q1, and the other end of the capacitor C101 is connected to the source of the charging MOSFET Q1. The resistor R100 is connected in series with the gate of the charging MOSFET Q1. When the lithium battery is fully charged, the charging MOSFET Q1 is turned off, and the supercapacitor C100 is connected in series with the lithium battery to form a new battery pack. The new battery pack is connected in parallel with the generator to stabilize the generator's output voltage. When the lithium battery needs to be charged, the charging MOSFET Q1 is turned on, and the supercapacitor C100 releases its charge through the charging MOSFET Q1. The discharge process delay unit ensures that the gate voltage of the charging MOSFET Q1 rises slowly and the discharge current of the charging MOSFET Q1 increases slowly, preventing the supercapacitor C100 from causing excessive discharge current after the charging MOSFET Q1 is turned on.

2. The charge / discharge protection circuit according to claim 1, characterized in that, The positive terminal of the supercapacitor C100 is connected to the drain of the charging MOSFET Q1, and the negative terminal of the supercapacitor C100 is connected to the source of the charging MOSFET Q1.

3. The charge / discharge protection circuit according to claim 1, characterized in that, It also includes a control unit, which is connected to the charging MOSFET Q1 through the resistor R100. The control unit is used to control the charging MOSFET Q1 to turn on or off according to the voltage state of the lithium battery.

4. The charge / discharge protection circuit according to claim 2, characterized in that, The capacitance of the farad capacitor C100 is 1~50 farads.

5. The charge / discharge protection circuit according to claim 1, characterized in that, The discharge process duration of the discharge process delay unit is 5ms to 20ms.

6. A lithium battery pack management system, characterized in that, Includes the charge / discharge protection circuit as described in any one of claims 1-5.

7. A lithium battery pack, characterized in that, Includes the lithium battery pack management system as described in claim 6.

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