Battery protection circuit, battery protection board and battery module

Abstract

The utility model discloses a kind of battery protection circuit, battery protection board and battery module, including battery management circuit for the charge-discharge management of secondary battery;Output capacitor circuit is used to connect external power supply or power consumption load;Pre-charge control circuit, first resistance circuit and fuse form pre-charge loop;Fuse, first resistance circuit and pre-discharge control circuit form pre-discharge loop;When receiving power-on signal, main control chip controls pre-charge control circuit to turn on pre-charge control circuit to disconnect, controls battery management circuit to work;When receiving power-off signal, control battery management circuit to stop working control pre-discharge control circuit to turn on control pre-charge control circuit to disconnect, when pre-charge control circuit or pre-discharge control circuit fails, pre-charge loop or pre-discharge loop is disconnected by fuse, protection is carried out in time to improve the security of battery protection circuit.

Description

Technical Field

[0001] This utility model relates to the field of battery protection technology, and in particular to a battery protection circuit, a battery protection board, and a battery module. Background Technology

[0002] Currently, many outdoor energy storage power supplies use battery-powered pre-charge and pre-discharge circuits to pre-charge and pre-discharge the capacitors in the downstream modules. The pre-charge / pre-discharge circuits of the downstream capacitors need to be turned on by a MOSFET and the current is controlled by a series resistor to prevent the downstream module capacitors from being damaged by sparks or impacts due to instantaneous charging. However, if the MOSFET is accidentally turned on due to a drive failure (such as gate breakdown), it may cause continuous overcurrent or short circuit. Traditional solutions rely solely on current detection chips for protection, which carries the risk of response delay or logic failure. Utility Model Content

[0003] This utility model provides a battery protection circuit, a battery protection board, and a battery module to solve the problem of failure risk in existing battery protection circuits.

[0004] A battery protection circuit includes a battery management circuit, a first resistor circuit, a fuse, an output capacitor circuit, a pre-charge control circuit, a pre-discharge control circuit, and a main control chip. The battery management circuit is used to connect to the secondary battery and to manage the charging and discharging of the secondary battery. The output capacitor circuit is connected to the battery management circuit and is used to connect to an external power source or electrical load. The pre-charge control circuit, the first resistor circuit, and the fuse are connected in series between the secondary battery and the output capacitor circuit to form a pre-charge circuit. The fuse, the first resistor circuit, and the pre-discharge control circuit are connected in series between the output capacitor circuit and ground to form a pre-discharge circuit. The main control chip is connected to the battery management circuit, the pre-charge control circuit, and the pre-discharge control circuit. When a power-on signal is received, it controls the pre-charge control circuit to turn on and, after controlling the pre-charge control circuit to turn off, controls the battery management circuit to operate. When a power-off signal is received, it controls the battery management circuit to stop operating, controls the pre-discharge control circuit to turn on, and controls the pre-charge control circuit to turn off.

[0005] Furthermore, the first resistor circuit includes a single resistor or multiple resistors; the multiple resistors are arranged in series and / or in parallel.

[0006] Furthermore, the pre-charge control circuit includes a first transistor, a first voltage divider circuit, a second transistor, a second voltage divider circuit, a third transistor, and a third voltage divider circuit; The first terminal of the first transistor is connected to the secondary battery, and the second terminal of the first transistor is connected to the first resistor circuit. The first terminal of the first voltage divider circuit is connected to the secondary battery, the second terminal of the first voltage divider circuit is connected to the first terminal of the second transistor, and the third terminal of the first voltage divider circuit is connected to the third terminal of the first transistor; the second terminal of the second transistor is grounded. The first terminal of the second voltage divider circuit is connected to the first control terminal of the main control chip, the second terminal of the second voltage divider circuit is grounded, and the third terminal of the second voltage divider circuit is connected to the third terminal of the second transistor. The first terminal of the third transistor is connected to the third terminal of the second transistor, and the second terminal of the third transistor is grounded. The first terminal of the third voltage divider circuit is connected to the second control terminal of the main control chip, the second terminal of the third voltage divider circuit is grounded, and the third terminal of the third voltage divider circuit is connected to the third terminal of the third transistor.

[0007] Furthermore, the pre-discharge control circuit includes a fourth transistor, a second resistor circuit, a fifth transistor, a fourth voltage divider circuit, a sixth transistor, and a fifth voltage divider circuit; The first terminal of the fourth transistor is connected to the first resistor circuit, and the second terminal of the fourth transistor is grounded. The first terminal of the second resistor circuit is connected to the third terminal of the fourth transistor and the second terminal of the fifth transistor, and the second terminal of the second resistor circuit is grounded; the first terminal of the fifth transistor is connected to the first power supply terminal. The first terminal of the fourth voltage divider circuit is connected to the first power supply terminal, the second terminal of the fourth voltage divider circuit is connected to the first terminal of the sixth transistor, and the third terminal of the fourth voltage divider circuit is connected to the third terminal of the fifth transistor. The second terminal of the sixth transistor is grounded; the first terminal of the fifth voltage divider circuit is connected to the second control terminal of the main control chip, the second terminal of the fifth voltage divider circuit is grounded, and the third terminal of the fifth voltage divider circuit is connected to the third terminal of the sixth transistor.

[0008] Furthermore, the battery protection circuit includes a first auxiliary power supply; The first auxiliary power supply is connected to the secondary battery and the first power supply terminal, and is used to convert the output voltage of the secondary battery and output a first power supply voltage to the first power supply terminal.

[0009] Furthermore, the battery protection circuit includes a second auxiliary power supply; The second auxiliary power supply is connected to the first power supply terminal and the main control chip, and is used to convert the first power supply voltage and output the second power supply voltage to the main control chip.

[0010] A battery protection board includes a substrate and the aforementioned battery protection circuit; the battery protection circuit is disposed on the substrate; and the fuse is located above the first resistor circuit.

[0011] Furthermore, a floating gap is formed between the fuse and the first resistor circuit, the floating gap being 4.5 mm to 5.5 mm.

[0012] Furthermore, the buoyancy gap is filled with silicone.

[0013] A battery module includes a secondary battery and the aforementioned battery protection board; the secondary battery is connected to the battery protection board.

[0014] This utility model embodiment provides a battery protection circuit, a battery protection board, and a battery module. The battery protection circuit includes a battery management circuit, a first resistor circuit, a fuse, an output capacitor circuit, a pre-charge control circuit, a pre-discharge control circuit, and a main control chip. The battery management circuit is used to connect to a secondary battery and manage its charge and discharge. The output capacitor circuit is connected to the battery management circuit and is used to connect to an external power source or electrical load. The pre-charge control circuit, the first resistor circuit, and the fuse are connected in series between the secondary battery and the output capacitor circuit to form a pre-charge circuit. The fuse, the first resistor circuit, and the pre-discharge control circuit are connected in series between the output capacitor circuit and ground to form a pre-charge circuit. The pre-discharge circuit is connected to the main control chip, battery management circuit, pre-charge control circuit, and pre-discharge control circuit. Upon receiving a power-on signal, it controls the pre-charge control circuit to turn on and, after turning it off, controls the battery management circuit to operate. Upon receiving a power-off signal, it controls the battery management circuit to stop operating, controls the pre-discharge control circuit to turn on, and controls the pre-charge control circuit to turn off. If a fault in the pre-charge or pre-discharge control circuit causes the first resistor circuit to overheat, a fuse will disconnect the pre-charge or pre-discharge circuit. This ensures timely protection in case of a fault in the pre-charge or pre-discharge control circuit, improving the safety of the battery protection circuit. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a battery protection circuit in one embodiment of the present invention; Figure 2 This is another schematic diagram of the battery protection circuit in one embodiment of the present invention; Figure 3 This is a schematic diagram of a battery protection board in one embodiment of the present invention.

[0017] In the diagram: 1. Secondary battery; 21. Battery management circuit; 22. First resistor circuit; 23. Fuse; 24. Output capacitor circuit; 25. Pre-charge control circuit; 26. Pre-discharge control circuit; 27. Main control chip; 28. First auxiliary power supply; 29. ​​Second auxiliary power supply. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.

[0019] It should be understood that this invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this invention to those skilled in the art.

[0020] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. When used herein, the singular forms “a,” “an,” and “ / the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “comprising,” when used in this specification, identify the presence of features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0021] To fully understand this utility model, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by this utility model. Preferred embodiments of this utility model are described in detail below; however, in addition to these detailed descriptions, this utility model may have other embodiments.

[0022] This embodiment provides a battery protection circuit, such as Figure 1As shown, the circuit includes a battery management circuit 21, a first resistor circuit 22, a fuse 23, an output capacitor circuit 24, a pre-charge control circuit 25, a pre-discharge control circuit 26, and a main control chip 27. The battery management circuit 21 is connected to the secondary battery 1 and is used to manage the charging and discharging of the secondary battery 1. The output capacitor circuit 24 is connected to the battery management circuit 21 and is used to connect to an external power source or electrical load. The pre-charge control circuit 25, the first resistor circuit 22, and the fuse 23 are sequentially connected in series between the secondary battery 1 and the output capacitor circuit 24 to form a pre-charge circuit. The fuse 23... The first resistor circuit 22 and the pre-discharge control circuit 26 are connected in series between the output capacitor circuit 24 and ground to form a pre-discharge loop. The main control chip 27 is connected to the battery management circuit 21, the pre-charge control circuit 25 and the pre-discharge control circuit 26. When a power-on signal is received, the main control chip 27 controls the pre-charge control circuit 25 to turn on and controls the battery management circuit 21 to work after the pre-charge control circuit 25 is turned off. When a power-off signal is received, the main control chip 27 controls the battery management circuit 21 to stop working, controls the pre-discharge control circuit 26 to turn on and controls the pre-charge control circuit 25 to turn off.

[0023] As an example, battery management circuit 21 is used to connect to secondary battery 1 and to manage the charging and discharging of secondary battery 1. Battery management circuit 21 includes a BMS (Battery Management System) module for managing the charging and discharging of secondary battery 1. Optionally, secondary battery 1 can be a lithium-ion battery or a sodium-ion battery. The charging and discharging management includes real-time monitoring of battery parameters such as voltage, current, and temperature; estimating remaining charge (SOC) and state of health (SOH); preventing dangerous situations such as overcharging, over-discharging, overcurrent, and short circuits; and avoiding battery damage or fire.

[0024] As an example, the output capacitor circuit 24 is connected to the battery management circuit 21 for connecting to an external power source or electrical load. Exemplarily, the battery management circuit 21 includes a positive output terminal PACK+ and a negative output terminal PACK-. The first terminal of the output capacitor circuit 24 is connected to the positive output terminal PACK+ of the battery management circuit 21, and the second terminal of the output capacitor circuit 24 is connected to the negative output terminal PACK- of the battery management circuit 21. Optionally, the output capacitor circuit 24 may include multiple output capacitors connected in parallel, which can be selected according to actual needs and is not limited here. Exemplarily, the external power source can be a power adapter or an energy storage device.

[0025] As an example, the pre-charge control circuit 25, the first resistor circuit 22, and the fuse 23 are connected in series between the secondary battery 1 and the output capacitor circuit 24 to form a pre-charge circuit. In this embodiment, when the output capacitor circuit 24 is pre-charged, the pre-charge control circuit 25 is turned on, and the pre-charge control circuit 25, the first resistor circuit 22, and the fuse 23 form a pre-charge circuit, pre-charging the output capacitor circuit 24 through the electrical signal output by the secondary battery 1. The first resistor circuit 22 is used to limit the pre-charge current. The fuse 23 is used when the pre-charge control circuit 25 fails, and the pre-charge circuit is in an uncontrolled state, the pre-charge current continues to pass through the first resistor circuit 22, causing the first resistor circuit 22 to continuously heat up. When the temperature reaches the melting temperature of the fuse 23, the fuse 23 can disconnect the pre-charge circuit, effectively preventing safety accidents caused by excessive temperature and improving the safety of the battery protection circuit.

[0026] As an example, the fuse 23, the first resistor circuit 22, and the pre-discharge control circuit 26 are connected in series between the output capacitor circuit 24 and ground to form a pre-discharge circuit. In this embodiment, when the output capacitor circuit 24 is pre-discharged, the pre-discharge control circuit 26 is turned on, and the fuse 23, the first resistor circuit 22, and the pre-discharge control circuit 26 form a pre-discharge circuit, releasing the energy stored in the output capacitor circuit 24 to ground. The first resistor circuit 22 is used to limit the pre-discharge current. The fuse 23 is used when the pre-discharge control circuit 26 fails, and the pre-discharge circuit is in an uncontrolled state, the pre-discharge current continues to pass through the first resistor circuit 22, which causes the first resistor circuit 22 to continuously heat up. When the temperature reaches the melting temperature of the fuse 23, the fuse 23 can disconnect the pre-discharge circuit, effectively preventing safety accidents caused by excessive temperature and improving the safety of the battery protection circuit.

[0027] As an example, the main control chip 27 is connected to the battery management circuit 21, the pre-charge control circuit 25, and the pre-discharge control circuit 26. Upon receiving a power-on signal, it controls the pre-charge control circuit 25 to turn on, and then controls the battery management circuit 21 to operate. Upon receiving a power-off signal, it controls the battery management circuit 21 to stop operating, controls the pre-discharge control circuit 26 to turn on, and controls the pre-charge control circuit 25 to turn off. Exemplarily, the power-on or power-off signal can be triggered by a button. When the power-on signal is received, the main control chip 27 first controls the pre-charge control circuit 25 to turn on and the pre-discharge control circuit 26 to turn off, pre-charging the output capacitor circuit 24. Then, it controls the battery management circuit 21 to start operating, managing the charge and discharge of the secondary battery 1, thereby preventing the output capacitor circuit 24 from charging instantaneously during the power-on process. Upon receiving a shutdown signal, the main control chip 27 first controls the battery management circuit 21 to stop working, controls the pre-discharge control circuit 26 to turn on, releases the stored energy to ground through the pre-discharge circuit, and simultaneously controls the pre-charge control circuit 25 to turn off, preventing the pre-charge circuit and pre-discharge circuit from working simultaneously and causing a short circuit, thus ensuring the safety of the battery protection circuit.

[0028] In this embodiment, the battery protection circuit includes a battery management circuit 21, a first resistor circuit 22, a fuse 23, an output capacitor circuit 24, a pre-charge control circuit 25, a pre-discharge control circuit 26, and a main control chip 27. The battery management circuit 21 is connected to the secondary battery 1 and is used to manage the charging and discharging of the secondary battery 1. The output capacitor circuit 24 is connected to the battery management circuit 21 and is used to connect to an external power source or electrical load. The pre-charge control circuit 25, the first resistor circuit 22, and the fuse 23 are connected in series between the secondary battery 1 and the output capacitor circuit 24 to form a pre-charge circuit. The fuse 23, the first resistor circuit 22, and the pre-discharge control circuit 26 are connected in series between the output capacitor circuit 24 and ground to form a pre-discharge circuit. The control chip 27 is connected to the battery management circuit 21, the pre-charge control circuit 25, and the pre-discharge control circuit 26. When a power-on signal is received, it controls the pre-charge control circuit 25 to turn on and, after the pre-charge control circuit 25 turns off, controls the battery management circuit 21 to operate. When a power-off signal is received, it controls the battery management circuit 21 to stop operating, controls the pre-discharge control circuit 26 to turn on, and controls the pre-charge control circuit 25 to turn off. If a fault occurs in the pre-charge control circuit 25 or the pre-discharge control circuit 26, causing the temperature of the first resistor circuit 22 to be too high, the fuse 23 will disconnect the pre-charge circuit or the pre-discharge circuit. This allows for timely protection when a fault occurs in the pre-charge control circuit 25 or the pre-discharge control circuit 26, improving the safety of the battery protection circuit.

[0029] In one embodiment, the first resistor circuit 22 includes a single resistor or multiple resistors; the multiple resistors are arranged in series and / or in parallel. In this embodiment, the first resistor circuit 22 is connected in series between the precharge control circuit 25 and the fuse 23, and in series between the fuse 23 and the pre-discharge control circuit 26. When the first resistor circuit 22 includes multiple resistors, the multiple resistors are arranged in series and / or in parallel. It is understood that the magnitude of the precharge current or pre-discharge current can be adjusted by the resistance value presented by the first resistor circuit 22. For example, as... Figure 1 As shown, the first resistor circuit 22 includes resistors R127, R128 and R129 connected in parallel.

[0030] In one embodiment, the pre-charge control circuit 25 includes a first transistor Q16, a first voltage divider circuit, a second transistor Q19, a second voltage divider circuit, a third transistor Q20, and a third voltage divider circuit. The first terminal of the first transistor Q16 is connected to the secondary battery 1, and the second terminal of the first transistor Q16 is connected to the first resistor circuit 22. The first terminal of the first voltage divider circuit is connected to the secondary battery 1, the second terminal of the first voltage divider circuit is connected to the first terminal of the second transistor Q19, and the third terminal of the first voltage divider circuit is connected to the third terminal of the first transistor Q16. The second terminal of the second transistor Q19 is grounded. The first terminal of the second voltage divider circuit is connected to the first control terminal of the main control chip 27, the second terminal of the second voltage divider circuit is grounded, and the third terminal of the second voltage divider circuit is connected to the third terminal of the second transistor Q19. The first terminal of the third transistor Q20 is connected to the third terminal of the second transistor Q19, and the second terminal of the third transistor Q20 is grounded. The first terminal of the third voltage divider circuit is connected to the second control terminal of the main control chip 27, the second terminal of the third voltage divider circuit is grounded, and the third terminal of the third voltage divider circuit is connected to the third terminal of the third transistor Q20.

[0031] As an example, the first transistor Q16 is a MOSFET, specifically a PMOS transistor. The first terminal of the first transistor Q16 is the source, the second terminal is the drain, and the third terminal is the gate. The second transistor Q19 and the third transistor Q20 are both transistors. Specifically, both the second transistor Q19 and the third transistor Q20 are NPN transistors. The first terminal of both the second transistor Q19 and the third transistor Q20 is the collector, the second terminal is the emitter, and the third terminal is the base.

[0032] As an example, such as Figure 2As shown, the first voltage divider circuit includes resistors R130 and R131. Resistors R130 and R131 are connected in series between the secondary battery 1 and the first terminal of the second transistor Q19, and the connection node between resistors R130 and R131 is connected to the third terminal of the first transistor Q16.

[0033] As an example, such as Figure 2 As shown, the second voltage divider circuit includes resistors R132 and R135. Resistors R132 and R135 are connected in series between the first control terminal of the main control chip 27 and ground, and the connection node between resistors R132 and R135 is connected to the third terminal of the second transistor Q19.

[0034] As an example, such as Figure 2 As shown, the third voltage divider circuit includes resistors R137 and R138. Resistors R137 and R138 are connected in series between the second control terminal of the main control chip 27 and ground, and the connection node between resistors R137 and R138 is connected to the third terminal of the third transistor Q20.

[0035] For example, when the main control chip 27 receives a power-on signal, its first control terminal outputs a high-level signal to turn on the second transistor Q19. The second control terminal of the main control chip 27 then turns off the third transistor Q20. After the second transistor Q19 turns on, it drives the first transistor Q16 to turn on. The electrical signal output by the secondary battery 1 charges the output capacitor circuit 24 through the first resistor circuit 22 and the fuse 23. Understandably, the conduction time of the first transistor Q16 determines the pre-charging time, and the resistance value of the first resistor circuit 22 determines the magnitude of the pre-charging current. After pre-charging is complete, the main control chip 27 controls the battery management circuit 21 to operate normally. When the main control chip 27 receives a power-off signal, its second control terminal outputs a high-level signal to turn on the third transistor Q20, thereby forcibly pulling down the level of the third terminal of the second transistor Q19 to prevent the pre-charging circuit and the pre-discharging circuit from operating simultaneously.

[0036] Furthermore, such as Figure 2 As shown, the second terminal of the first transistor Q16 is connected to the first resistor circuit 22 through diodes D16 and D17 in parallel to prevent reverse current from flowing into the output capacitor circuit 24. A Zener diode ZD5 is provided between the first and third terminals of the first transistor Q16 to ensure the stability of the operation of the first transistor Q16.

[0037] In this embodiment, pre-charge control is achieved through a first transistor Q16, a first voltage divider circuit, a second transistor Q19, a second voltage divider circuit, a third transistor Q20, and a third voltage divider circuit. The circuit structure is simple, the cost is low, and the stability and reliability are high.

[0038] In one embodiment, such as Figure 2 As shown, the pre-discharge control circuit 26 includes a fourth transistor Q17, a second resistor circuit, a fifth transistor Q18, a fourth voltage divider circuit, a sixth transistor Q21, and a fifth voltage divider circuit. The first terminal of the fourth transistor Q17 is connected to the first resistor circuit 22, and the second terminal of the fourth transistor Q17 is grounded. The first terminal of the second resistor circuit is connected to the third terminal of the fourth transistor Q17 and the second terminal of the fifth transistor Q18, and the second terminal of the second resistor circuit is grounded. The first terminal of the fifth transistor Q18 is connected to the first power supply terminal. The first terminal of the fourth voltage divider circuit is connected to the first power supply terminal, the second terminal of the fourth voltage divider circuit is connected to the first terminal of the sixth transistor Q21, and the third terminal of the fourth voltage divider circuit is connected to the third terminal of the fifth transistor Q18. The second terminal of the sixth transistor Q21 is grounded. The first terminal of the fifth voltage divider circuit is connected to the second control terminal of the main control chip 27, the second terminal of the fifth voltage divider circuit is grounded, and the third terminal of the fifth voltage divider circuit is connected to the third terminal of the sixth transistor Q21.

[0039] As an example, the fourth transistor Q17, the fifth transistor Q18, and the sixth transistor Q21 are all MOSFETs. Exemplarily, the fourth transistor Q17 is an NMOS transistor. The first terminal of the fourth transistor Q17 is the drain, the second terminal is the source, and the third terminal is the gate. The fifth transistor Q18 is a PMOS transistor. The first terminal of the fifth transistor Q18 is the source, the second terminal is the drain, and the third terminal is the gate. The sixth transistor Q21 is an NMOS transistor. The first terminal of the sixth transistor Q21 is the drain, the second terminal is the source, and the third terminal is the gate.

[0040] As an example, the second resistor circuit includes a single resistor or multiple resistors, which may be arranged in series or parallel. In this example, such as Figure 2 As shown, the second resistor circuit includes resistor R134.

[0041] As an example, such as Figure 2 As shown, the fourth voltage divider circuit includes resistors R133 and R139. Resistors R133 and R139 are connected in series between the first control terminal of the main control chip 27 and ground, and the connection node between resistors R132 and R135 is connected to the third terminal of the second transistor Q19.

[0042] As an example, such as Figure 2 As shown, the fifth voltage divider circuit includes resistors R143 and R146. Resistors R143 and R146 are connected in series between the second control terminal of the main control chip 27 and ground. The connection node between resistors R143 and R146 is connected to the third terminal of the sixth transistor Q21.

[0043] For example, when the main control chip 27 receives a power-off signal, its second control terminal outputs a high-level signal, controlling the third transistor Q20 to conduct. This forces the level at the third terminal of the second transistor Q19 to be pulled low, preventing the pre-charge circuit from operating. This then turns on the sixth transistor Q21, driving the fifth transistor Q18 to conduct. The first power supply voltage provided by the first power supply terminal drives the fourth transistor Q17 to conduct, thus forming a pre-discharge circuit with the fuse 23 and the first resistor circuit 22. When the main control chip 27 receives a power-on signal, its second control terminal either does not output a signal or outputs a low-level signal, causing the pre-charge circuit to operate while the pre-discharge circuit does not, thereby preventing the pre-charge and pre-discharge circuits from operating simultaneously.

[0044] Furthermore, the second control terminal of the main control chip 27 is connected to the third terminal of the third transistor Q20 through diode D24, and to the third terminal of the sixth transistor Q21 through diode D25.

[0045] In this embodiment, pre-discharge control is achieved through the fourth transistor Q17, the second resistor circuit, the fifth transistor Q18, the fourth voltage divider circuit, the sixth transistor Q21, and the fifth voltage divider circuit. The circuit structure is simple, the cost is low, and the stability and reliability are high.

[0046] In one embodiment, such as Figure 1 As shown, the battery protection circuit includes a first auxiliary power supply 28; the first auxiliary power supply 28 is connected to the secondary battery 1 and the first power supply terminal, and is used to convert the output voltage of the secondary battery 1 and output the first power supply voltage to the first power supply terminal.

[0047] For example, the first auxiliary power supply 28 includes a first step-down circuit, such as a synchronous step-down converter, which converts the output voltage of the secondary battery 1 into 12V to provide a first power supply voltage to the fourth transistor Q17, so as to ensure that the fourth transistor Q17 can work stably.

[0048] In one embodiment, such as Figure 1 As shown, the battery protection circuit includes a second auxiliary power supply 29; the second auxiliary power supply 29 is connected to the first power supply terminal and the main control chip 27, and is used to convert the first power supply voltage and output the second power supply voltage to the main control chip 27.

[0049] For example, the second auxiliary power supply 29 includes a second step-down circuit, such as a low-dropout linear regulator, to convert the 12V first supply voltage into a 3.3V second supply voltage to ensure that the main control chip 27 can work stably.

[0050] This embodiment provides a battery protection board, including a substrate and the aforementioned battery protection circuit; the battery protection circuit is disposed on the substrate; the fuse 23 is located above the first resistor circuit 22.

[0051] Optionally, such as Figure 3 As shown, the fuse 23 can be floated above the first resistor circuit 22 or attached to the first resistor circuit 22.

[0052] For example, a floating gap is formed between the fuse 23 and the first resistor circuit 22, the floating gap being 4.5 mm to 5.5 mm, preferably 5 mm, and is welded above the midpoint between two adjacent resistors in the first resistor circuit 22, such as... Figure 3 As shown, for example, the first resistor circuit 22 includes resistors R127, R128 and R129 connected in parallel. The fuse 23 is soldered above the middle position of resistors R127 and R129 to achieve effective temperature detection. Floating installation is more accurate in temperature sampling than surface mounting, and the fuse is not affected by external equipment during the process. Therefore, when the temperature of the first resistor circuit 22 is too high, the pre-charge circuit or pre-discharge circuit can be disconnected in time.

[0053] In one embodiment, the fuse 23 is fixed to the first resistive circuit 22 with silicone to ensure the robustness of the fuse 23.

[0054] This embodiment provides a battery module, including a secondary battery 1 and the aforementioned battery protection board; the secondary battery 1 is connected to the battery protection board.

[0055] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. A battery protection circuit, characterized in that, It includes a battery management circuit, a first resistor circuit, a fuse, an output capacitor circuit, a pre-charge control circuit, a pre-discharge control circuit, and a main control chip; The battery management circuit is used to connect to the secondary battery and to manage the charging and discharging of the secondary battery. The output capacitor circuit is connected to the battery management circuit and is used to connect to an external power source or electrical load. The pre-charge control circuit, the first resistor circuit, and the fuse are connected in series between the secondary battery and the output capacitor circuit to form a pre-charge circuit. The fuse, the first resistor circuit, and the pre-discharge control circuit are connected in series between the output capacitor circuit and ground to form a pre-discharge circuit. The main control chip is connected to the battery management circuit, the pre-charge control circuit, and the pre-discharge control circuit. When a power-on signal is received, it controls the pre-charge control circuit to turn on and, after controlling the pre-charge control circuit to turn off, controls the battery management circuit to operate. When a power-off signal is received, it controls the battery management circuit to stop operating, controls the pre-discharge control circuit to turn on, and controls the pre-charge control circuit to turn off.

2. The battery protection circuit of claim 1, wherein, The first resistor circuit includes a single resistor or multiple resistors; the multiple resistors are arranged in series and / or in parallel.

3. The battery protection circuit of claim 1, wherein, The precharge control circuit includes a first transistor, a first voltage divider circuit, a second transistor, a second voltage divider circuit, a third transistor, and a third voltage divider circuit. The first terminal of the first transistor is connected to the secondary battery, and the second terminal of the first transistor is connected to the first resistor circuit. The first terminal of the first voltage divider circuit is connected to the secondary battery, the second terminal of the first voltage divider circuit is connected to the first terminal of the second transistor, and the third terminal of the first voltage divider circuit is connected to the third terminal of the first transistor; the second terminal of the second transistor is grounded. The first terminal of the second voltage divider circuit is connected to the first control terminal of the main control chip, the second terminal of the second voltage divider circuit is grounded, and the third terminal of the second voltage divider circuit is connected to the third terminal of the second transistor. The first terminal of the third transistor is connected to the third terminal of the second transistor, and the second terminal of the third transistor is grounded. The first terminal of the third voltage divider circuit is connected to the second control terminal of the main control chip, the second terminal of the third voltage divider circuit is grounded, and the third terminal of the third voltage divider circuit is connected to the third terminal of the third transistor.

4. The battery protection circuit of claim 1, wherein, The pre-discharge control circuit includes a fourth transistor, a second resistor circuit, a fifth transistor, a fourth voltage divider circuit, a sixth transistor, and a fifth voltage divider circuit. The first terminal of the fourth transistor is connected to the first resistor circuit, and the second terminal of the fourth transistor is grounded. The first terminal of the second resistor circuit is connected to the third terminal of the fourth transistor and the second terminal of the fifth transistor, and the second terminal of the second resistor circuit is grounded; the first terminal of the fifth transistor is connected to the first power supply terminal. The first terminal of the fourth voltage divider circuit is connected to the first power supply terminal, the second terminal of the fourth voltage divider circuit is connected to the first terminal of the sixth transistor, and the third terminal of the fourth voltage divider circuit is connected to the third terminal of the fifth transistor. The second terminal of the sixth transistor is grounded; the first terminal of the fifth voltage divider circuit is connected to the second control terminal of the main control chip, the second terminal of the fifth voltage divider circuit is grounded, and the third terminal of the fifth voltage divider circuit is connected to the third terminal of the sixth transistor.

5. The battery protection circuit of claim 4, wherein, The battery protection circuit includes a first auxiliary power supply; The first auxiliary power supply is connected to the secondary battery and the first power supply terminal, and is used to convert the output voltage of the secondary battery and output a first power supply voltage to the first power supply terminal.

6. The battery protection circuit of claim 5, wherein, The battery protection circuit includes a second auxiliary power supply; The second auxiliary power supply is connected to the first power supply terminal and the main control chip, and is used to convert the first power supply voltage and output the second power supply voltage to the main control chip.

7. A battery protection plate, characterized in that It includes a substrate and a battery protection circuit as described in any one of claims 1 to 6; the battery protection circuit is disposed on the substrate; the fuse is located above the first resistor circuit.

8. The battery protection plate of claim 7, wherein, A floating gap is formed between the fuse and the first resistor circuit, the floating gap being 4.5 mm to 5.5 mm.

9. The battery protection plate of claim 8, wherein, The buoyancy gap is filled with silicone.

10. A battery module, characterized by It includes a secondary battery and a battery protection board as described in any one of claims 7 to 9; the secondary battery is connected to the battery protection board.

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