Charging and discharging protection circuit, lithium battery pack management system and lithium battery pack

Abstract

The invention discloses a charging and discharging protection circuit, a lithium battery pack management system and a lithium battery pack, the charging and discharging protection circuit is applied to a lithium battery protection board, the charging and discharging protection circuit comprises a protection module, the protection module is connected in parallel with a charging MOS tube Q1, one end of the protection module is used for connecting an electric load and a generator, and the other end of the electric load and the other end of the generator are connected with the positive electrode of a lithium battery; the other end of the protection module is connected with the negative electrode of the lithium battery through a discharge MOS tube Q2; the protection module comprises a farad capacitor C100, and the farad capacitor C100 is connected in parallel with the charging MOS tube Q1; when the lithium battery is fully charged, the charging MOS tube Q1 is turned off, the farad capacitor C100 is connected with the lithium battery in series to form a new battery pack, and the new battery pack is connected with the generator in parallel to stabilize the output voltage of the generator. The output voltage of the generator is stabilized, and voltage fluctuation caused by suspension of the generator after the lithium battery is fully charged is prevented.

Description

Technical Field

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

[0002] After the lithium battery is fully charged, the general charging control circuit usually turns off the charging field effect transistor (MOSFET) Q1 to prevent overcharging. However, in this case, the freewheeling current generated by the generator inductive energy storage will make the generator output voltage significantly higher than the lithium battery voltage, resulting in a voltage difference between the generator and the lithium battery. Since the generator is suspended outside the lithium battery and there is no stable load to absorb electrical energy, this voltage difference will cause significant voltage fluctuations.

[0003] Voltage fluctuations have many effects on the vehicle's electrical system, the most obvious of which is the flickering of the car's lights. This not only affects the driving experience, but may also have adverse effects on other electronic devices in the vehicle. Therefore, how to effectively control the fluctuation of the generator output voltage after the lithium battery is fully charged has become a technical problem that needs to be solved urgently.

[0004] Although some existing solutions can alleviate the problem of voltage fluctuation to a certain extent, most of them have defects such as complex design, high cost and unsatisfactory effect. Therefore, it is an urgent problem to develop an efficient and cost-effective technical means to stabilize the output voltage of the generator and prevent the voltage fluctuation caused by the generator suspension after the lithium battery is fully charged. Summary of the invention

[0005] In order to overcome the above technical problems, the present invention provides a charge and discharge protection circuit, a lithium battery pack management system, and a lithium battery pack to stabilize the output voltage of the generator and prevent voltage fluctuations caused by generator suspension after the lithium battery is fully charged.

[0006] In a first aspect, the present invention provides a charge and discharge protection circuit, which is applied to a lithium battery protection board, wherein a charging MOS tube Q1 and a discharging MOS tube Q2 connected to the lithium battery are provided on the protection board;

[0007] The charge and discharge protection circuit comprises:

[0008] A protection module, the protection module is connected in parallel to the charging MOS tube Q1, one end of the protection module is used to connect the power load and the generator, and the other end of the power load and the generator is connected to the positive electrode of the lithium battery; the other end of the protection module is connected to the negative electrode of the lithium battery through the discharging MOS tube Q2;

[0009] The protection module includes a farad capacitor C100, and the farad capacitor C100 is connected in parallel to the charging MOS tube Q1;

[0010] When the lithium battery is fully charged, the charging MOS tube Q1 is turned off, and the farad capacitor C100 is connected in series with the lithium battery to form a new battery pack, which is connected in parallel to the generator to stabilize the output voltage of the generator.

[0011] In some implementations, the positive electrode of the farad capacitor C100 is connected to the drain of the charging MOS transistor Q1, and the negative electrode of the farad capacitor C100 is connected to the source of the charging MOS transistor Q1.

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

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

[0014] In some embodiments, a control unit is further included, and the control unit is connected to the charging MOS tube Q1 through the resistor R100. The control unit is used to control the charging MOS tube Q1 to be turned on or off according to the voltage state of the lithium battery.

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

[0016] In some embodiments, when the lithium battery needs to be charged, the charging MOS tube Q1 is turned on, and the farad capacitor C100 releases electricity through the charging MOS tube Q1.

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

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

[0019] In a third aspect, the present invention provides a lithium battery pack, comprising the lithium battery pack management system as described above.

[0020] The present invention provides a charge and discharge protection circuit, a lithium battery pack management system, and a lithium battery pack. The setting of the protection module can effectively absorb and stabilize the voltage fluctuation of the generator, ensure that after the lithium battery is fully charged, the voltage of the generator in the suspended state is stable, reduce the phenomenon of vehicle light flickering, protect the charging field effect tube and other sensitive electronic components from overvoltage damage, and extend the service life of the components. After the lithium battery is fully charged, the output voltage of the generator continues to be stabilized, significantly reducing voltage fluctuations, thereby enhancing the reliability of the entire circuit system. The design of this application simplifies the circuit structure, reduces manufacturing and maintenance costs, and at the same time improves the charging efficiency of the lithium battery, ensuring the stable operation of the system under various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0023] Figure 3 It is the voltage waveform when the charging MOS tube Q1 is turned off when there is no protection module. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] In the above description, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0029] like Figure 1 As shown, the present application provides a charge and discharge protection circuit, which is applied to a lithium battery protection board. By setting a protection module, the voltage fluctuation of the generator is absorbed to prevent the voltage fluctuation caused by the suspension of the generator after the lithium battery is fully charged.

[0030] Specifically, the present application is applied to a lithium battery protection board, on which a charging MOS tube Q1 and a discharging MOS tube Q2 connected to the lithium battery are provided; a protection module, the protection module is connected in parallel to the charging MOS tube Q1, one end of the protection module is used to connect the power load and the generator, and the other end of the power load and the generator is connected to the positive electrode of the lithium battery; the other end of the protection module is connected to the negative electrode of the lithium battery through the discharging MOS tube Q2.

[0031] When the lithium battery is fully charged, the charging MOS tube 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 and connected in parallel with the generator. The lithium battery and the protection module perform appropriate voltage distribution, absorb current impact, and balance with the generator voltage to stabilize the output voltage of the generator.

[0032] In this embodiment, the protection module includes a farad capacitor C100, which absorbs voltage shocks through the farad capacitor. The farad capacitor C100 is connected in parallel to the charging MOS tube Q1. When the MOS tube Q1 is turned off, the farad capacitor 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 output voltage of the generator. The capacity of the farad capacitor C100 can be reasonably set according to the capacity of the lithium battery and the generator to fully absorb the voltage shock in the circuit. In this application, the farad capacitor C100 is 1 to 50 farads.

[0033] The voltage across the farad capacitor C100 changes as follows Figure 2 In the initial stage of charging, the generator starts to charge the lithium battery, and the output voltage of the generator gradually rises from the initial state along with the voltage of the lithium battery, while the farad capacitor C100 is short-circuited by the charging MOS tube Q1, and the voltage is always zero.

[0034] When the lithium battery is fully charged, the charging MOS tube Q1 is turned off, and the voltage of the generator is higher than the voltage of the lithium battery. However, since the charging MOS tube Q1 is turned off, the farad capacitor C100 and the lithium battery are immediately combined in series, and the generator voltage does not directly act on the lithium battery. It is stabilized by the combination of the farad capacitor C100 and the lithium battery in series.

[0035] The farad capacitor C100 is connected in series with the lithium battery and continues to maintain a parallel relationship with the generator. In this process, the voltage of the farad capacitor C100 rises slowly. Its voltage is the voltage of the generator minus the voltage of the lithium battery, absorbing and buffering the fluctuation of the generator voltage. Then the generator voltage rises to the rated value, maintaining a stable voltage output, and preventing the influence of voltage fluctuations on the circuit.

[0036] Until the next charging cycle, when the lithium battery needs to be charged, the charging MOS tube Q1 will be turned on, the positive electrode of the farad capacitor C100 is connected to the drain of the charging MOS tube Q1, and the negative electrode of the farad capacitor C100 is connected to the source of the MOS tube Q1. The voltage of the farad capacitor C100 is equal to the generator voltage minus the voltage of the lithium battery. When the lithium battery needs to be charged, the MOS tube Q1 is slowly turned on under the action of the discharge process delay unit R100 and C101, and the farad capacitor C100 slowly releases electricity through the charging MOS tube Q1.

[0037] In this application, the new battery pack formed by connecting the farad capacitor C100 in series with the lithium battery effectively absorbs and stabilizes the voltage fluctuation of the generator. When the lithium battery is fully charged, the voltage of the generator is higher than the voltage of the lithium battery. The generator is suspended outside the lithium battery and the voltage fluctuation is large. The farad capacitor C100 responds quickly and smoothes the voltage change to prevent the voltage mutation from affecting this circuit. During the shutdown period of the charging MOS tube Q1, the farad capacitor C100 absorbs and stabilizes the surge voltage output by the generator to avoid the following situation: Figure 3 The impulse voltage shown in the figure will damage the charging MOS tube Q1 and the lithium battery, thus extending the service life of the components. It ensures that the entire automotive circuit system can operate stably under various working conditions, avoids system failures or abnormalities caused by voltage fluctuations, and enhances the reliability of the circuit.

[0038] The introduction of the Farad capacitor C100 can effectively reduce the reliance on complex circuit design and additional electronic components, thereby simplifying circuit design and reducing manufacturing and maintenance costs. Since the fluctuation of the generator voltage may cause the vehicle lights to flicker, the setting of the Farad capacitor C100 can continue to stabilize the output voltage of the generator after the lithium battery is fully charged, significantly reducing this flickering phenomenon, improving driving safety and comfort, significantly improving the stability and reliability of the generator and lithium battery, and avoiding the negative impact of voltage fluctuations on the vehicle's electrical system.

[0039] Furthermore, the present application sets a discharge process delay unit, which includes a capacitor C101 and a resistor R100. The capacitor C101 is connected in parallel to the charging MOS tube Q1; the resistor R100 is connected in series with the gate of the charging MOS tube Q1. One end of the capacitor C101 is connected to the gate of the charging MOS tube Q1, and one end of the capacitor C101 is connected to the source of the charging MOS tube Q1. The resistance of the resistor R100 is greater than the resistance of the gate resistor of a conventional MOS tube. The resistor R100 is connected in parallel with the capacitor C101 to form a discharge process delay unit, so that the voltage of the gate of the charging MOS tube Q1 rises slowly, and the discharge current of the charging MOS tube Q1 increases slowly, so as to prevent the undesirable phenomenon that the discharge current of the farad capacitor C100 is too large after the charging MOS tube Q1 is turned on, and prolong the service life of the farad capacitor C100.

[0040] Furthermore, the present application further includes a control unit, which is connected to the charging MOS tube Q1 through a resistor R100, and is used to control the charging MOS tube Q1 to be turned on or off according to the voltage state of the lithium battery. In a specific embodiment, the control unit may be a BMS chip, which controls the charging MOS tube Q1 to be turned on or off according to the voltage state of the lithium battery to ensure that the lithium battery is charged and discharged under appropriate conditions, maintain the stability and reliability of the entire lithium battery system, reduce voltage fluctuations, and extend the service life of the lithium battery.

[0041] When the control unit detects that the lithium battery voltage is lower than the set charging threshold, that is, the lithium battery needs to be charged, the charging control terminal of the control unit sends a control signal to turn on the charging MOS tube Q1, thereby allowing the voltage of the generator to charge the lithium battery through the charging MOS tube Q1. When the control unit detects that the lithium battery voltage reaches or exceeds the set charging cut-off threshold, that is, the lithium battery is fully charged, the control unit will send a control signal to turn off the charging MOS tube Q1, stop further charging of the lithium battery, and prevent overcharging.

[0042] The control unit, that is, the charging control end of the BMS chip is connected to a resistor R100 that is larger than a conventional resistor, and C101 is connected in parallel to the gate and source of the charging MOS tube Q1, so that the charging MOS tube Q1 can be slowly turned on, so that the charge on the farad capacitor C100 is slowly released through the charging MOS tube Q1, reducing the impact current of the farad capacitor C100 on the charging MOS tube Q1. The discharge process can last for 5ms to 20ms.

[0043] When there are multiple lithium batteries in series, the control unit can balance the voltage of each battery cell, or manage the discharge process of the lithium battery, and control the discharge MOS tube Q2 to adjust the discharge of the lithium battery to the load or circuit to prevent overcharge or overdischarge of the battery in certain cases. The control unit can communicate with an external monitoring system, such as a Bluetooth module, to provide status information of the lithium battery and the system, facilitate remote monitoring and management, and provide necessary status feedback and communication functions.

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

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

[0046] The present invention provides a charge and discharge protection circuit, a lithium battery pack management system, and a lithium battery pack. The setting of the protection module can effectively absorb and stabilize the voltage fluctuation of the generator, ensure that after the lithium battery is fully charged, the voltage of the generator in the suspended state is stable, reduce the flickering of vehicle lights, and protect the charging field effect tube and other sensitive electronic components from damage by overvoltage, thereby extending the service life of the components. After the lithium battery is fully charged, the output voltage of the generator continues to be stabilized, significantly reducing voltage fluctuations, thereby enhancing the reliability of the entire circuit system. The design of this application simplifies the circuit structure, reduces manufacturing and maintenance costs, and at the same time improves the charging efficiency of the lithium battery, ensuring the stable operation of the system under various working conditions.

[0047] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A charge and discharge protection circuit, characterized in that: Applicable to a lithium battery protection board, on which a charging MOS tube Q1 and a discharging MOS tube Q2 connected to the lithium battery are provided; The charge and discharge protection circuit comprises: A protection module, the protection module is connected in parallel to the charging MOS tube Q1, one end of the protection module is used to connect the power load and the generator, and the other end of the power load and the generator is connected to the positive electrode of the lithium battery; the other end of the protection module is connected to the negative electrode of the lithium battery through the discharging MOS tube Q2; The protection module includes a farad capacitor C100, and the farad capacitor C100 is connected in parallel to the charging MOS tube Q1; When the lithium battery is fully charged, the charging MOS tube Q1 is turned off, and the farad capacitor C100 is connected in series with the lithium battery to form a new battery pack, which is connected in parallel to the generator to stabilize the output voltage of the generator.

2. The charge and discharge protection circuit according to claim 1, characterized in that: The positive electrode of the farad capacitor C100 is connected to the drain of the charging MOS tube Q1, and the negative electrode of the farad capacitor C100 is connected to the source of the charging MOS tube Q1.

3. The charge and discharge protection circuit according to claim 1, characterized in that: 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 to the charging MOS tube Q1; the resistor R100 is connected in series to the gate of the charging MOS tube Q1.

4. The charge and discharge protection circuit according to claim 3, characterized in that: One end of the capacitor C101 is connected to the gate of the charging MOS tube Q1 , and the other end of the capacitor C101 is connected to the source of the charging MOS tube Q1 .

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

6. The charge and discharge protection circuit according to claim 2, characterized in that: The capacity of the farad capacitor C100 is 1 to 50 farads.

7. The charge and discharge protection circuit according to claim 2, characterized in that: When the lithium battery needs to be charged, the charging MOS tube Q1 is turned on, and the farad capacitor C100 releases electricity through the charging MOS tube Q1.

8. The charge and discharge protection circuit according to claim 3, characterized in that: The discharge process duration of the discharge process delay unit is 5ms to 20ms.

9. A lithium battery pack management system, characterized in that: It comprises the charge and discharge protection circuit as described in any one of claims 1 to 8.

10. A lithium battery pack, characterized in that: Comprising the lithium battery pack management system as claimed in claim 9.

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