Lithium battery protection system for preventing overcharge

Abstract

The invention belongs to the technical field of battery protection, and particularly discloses a lithium battery protection system for preventing overcharge, which comprises a battery module, a switch unit, a logic control circuit and a state detection circuit, the switch unit is connected in a charging path of the battery module, one end of the switch unit is connected with the charging circuit, and the other end of the switch unit is connected with the logic control circuit. The state detection circuit comprises a voltage monitoring module, a current monitoring module and a temperature monitoring module which are connected and is used for detecting the state of the battery module and generating a state signal, the state signal is used for indicating the state of the battery module, and the logic control circuit receives the state signal from the state detection circuit and sends the state signal to the battery module. The switch unit is controlled according to the state signal to open and close the charging circuit; the state detection circuit is arranged to monitor the state of the battery module in real time, once it is detected that the battery is to be overcharged, the logic control circuit will close the switch unit to close the charging circuit, and the problem of explosion caused by overcharge of the battery module is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of battery protection, and in particular to a lithium battery protection system for preventing overcharging. Background Art

[0002] With the development of science and technology, lithium batteries are widely used in various electronic devices due to their high energy density, long cycle life and environmental protection. However, if lithium batteries are overcharged during use, the chemical reaction inside the battery may accelerate, generating a large amount of heat, causing the battery temperature to rise rapidly, triggering thermal runaway, and may even cause the battery to rupture, burn or even explode. In addition, overcharging may also cause the solvent in the electrolyte to decompose, generating a large amount of flammable gases such as hydrogen and oxygen, causing the internal pressure of the battery to increase, further exacerbating the risk of thermal runaway and explosion of the battery.

[0003] In order to solve the problem of lithium battery overcharging, the existing technology mainly sets a protection circuit inside the battery. When the battery voltage reaches a certain threshold, the protection circuit will automatically cut off the charging current to prevent the battery from overcharging.

[0004] Although the existing technology has solved the problem of lithium battery overcharging to a certain extent, there are still some problems and shortcomings. Most of the existing lithium batteries have always been posing the risk of explosion. When the lithium battery is overcharged, over-discharged or has an internal short circuit, it is easy to cause the working current to be too large, and the internal temperature of the battery to gradually increase; or when it is collided or squeezed during use, it will cause an explosion and pose a safety hazard. Summary of the invention

[0005] The object of the present invention is to provide a lithium battery protection system for preventing overcharging, so as to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a lithium battery protection system for preventing overcharging, comprising: a battery module, a switch unit, a logic control circuit and a status detection circuit, wherein the switch unit is connected in the charging path of the battery module, one end of the switch unit is connected to the charging circuit, the status detection circuit comprises a connected voltage monitoring module, a current monitoring module and a temperature monitoring module, which are used to detect the status of the battery module and generate a status signal, wherein the status signal is used to indicate the status of the battery module, the logic control circuit receives the status signal from the status detection circuit, and controls the switch unit according to the status signal to open and close the charging circuit.

[0007] Preferably, the state detection circuit includes a voltage monitoring module and a current monitoring module connected in parallel to the battery module;

[0008] Preferably, the voltage monitoring module is a high-precision voltage sensor, which monitors the voltage level of the battery module in real time. When the battery module is in the charging process, the voltage of the battery module gradually rises and approaches the preset overcharge threshold value, the voltage monitoring module will immediately send out an overcharge status signal, and the logic control circuit controls the switch unit to close after receiving the signal, cuts off the charging circuit and stops the charging process. When the voltage of the battery module drops below the preset undercharge threshold value during the discharge process, the voltage monitoring module will automatically identify this state and send out an undercharge status signal. After receiving the signal, the logic control circuit controls the switch unit to open, closes the charging circuit and resumes charging.

[0009] Preferably, the current monitoring module is a high-precision current sensor, which monitors the charging current data of the battery module in real time. The current monitoring module compares the collected charging current data with a preset safety threshold. When it is detected that the charging current exceeds the upper limit of the safety threshold, the logic control circuit sends a control signal to turn off the switch unit to cut off the charging circuit. When it is detected that the charging current is within the preset safety threshold, the logic control circuit sends a control signal to turn on the switch unit to maintain the charging state. When the battery module is fully charged and the charging current drops below the lower limit of the safety threshold, the logic control circuit sends a control signal to turn off the switch unit to stop active charging.

[0010] Preferably, the status detection circuit also includes a temperature monitoring module connected to the battery module, the temperature monitoring module includes a temperature sensor inserted into the battery module, the temperature sensor measures the internal temperature of the battery module in real time, the sensor responds to the temperature change of the battery module, and converts the temperature data into an electrical signal. The temperature monitoring module is preset with a temperature threshold, and the temperature threshold includes a high temperature threshold and a low temperature threshold. When the temperature of the battery module reaches or exceeds the high temperature threshold or is lower than the low temperature threshold, the temperature monitoring module sends a signal to the logic control circuit, and the logic control circuit sends a control signal to turn off the switch unit to cut off the charging circuit. When the temperature of the battery module returns to between the temperature thresholds, the temperature monitoring module re-sends a signal to the logic control circuit, and the logic control circuit sends a control signal to turn on the switch unit to restore the charging circuit.

[0011] Preferably, an explosion-proof device is provided on the battery module shell, and the explosion-proof device includes a safety valve arranged inside the battery module and an explosion-proof net arranged outside the battery module. Thermally conductive silicone sheets are fixedly installed on the upper and lower sides of the battery module. The shape of the thermally conductive silicone sheets is the same as the upper and lower end faces of the battery module and is arranged close to the upper and lower end faces of the battery module. The outermost part of the battery module is surrounded by a wrapped metal shell.

[0012] Preferably, the safety valve is based on a pressure sensor, which monitors the pressure changes inside the battery module in real time. The safety valve is pre-set with a burst value. When the internal pressure of the battery module exceeds the burst value set by the safety valve, the pressure sensor sends a signal to the safety valve. After receiving the signal, the safety valve opens the exhaust port to release the excessive pressure inside the battery module. After releasing the excessive pressure, the pressure inside the battery module will gradually decrease to a normal range. When the pressure monitored by the pressure sensor falls below the burst value, the safety valve automatically closes the exhaust port.

[0013] Preferably, a mounting hole is provided on one side of the metal shell, a heat dissipation fan is fixedly provided in the mounting hole, and a ventilation groove is penetrated through the end surface of the metal shell on the side opposite to the heat dissipation fan.

[0014] Preferably, the cooling fan is provided with an electromagnetic switch, and the cooling fan is electrically connected to a temperature monitoring module. The temperature monitoring module also presets the upper and lower temperature limits of the cooling fan switch to determine when to start and stop the cooling fan; when the battery module temperature exceeds the upper limit value, the temperature monitoring module transmits a signal to the electromagnetic valve to start the cooling fan to lower the battery module temperature; when the battery module temperature reaches or is lower than the lower temperature limit value, the temperature monitoring module transmits a signal to the electromagnetic valve to turn off the cooling fan to save energy.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention sets a state detection circuit to monitor the state of the battery module in real time, and detects the charging state in multiple ways by monitoring the current, voltage, and temperature. Once it is detected that the battery is about to be overcharged, the logic control circuit will immediately turn off the switch unit to turn off the charging circuit, thereby avoiding the acceleration of the chemical reaction speed inside the battery module, preventing the internal pressure of the battery from increasing, and preventing the electrolyte from decomposing and producing gas, thereby causing problems such as battery expansion, leakage, and even explosion; the battery module of the present invention is provided with a heat dissipation mechanism, and the heat dissipation fan runs when the battery module is heated. A ventilation groove is provided at one end of the metal shell to accelerate the circulation of air between the battery module and the metal shell to take away the high heat. At the same time, thermal conductive silicone sheets are provided at the upper and lower ends of the battery module to also improve the heat extraction of the battery module; the present invention sets an explosion-proof net on the outside of the battery module. When the battery cannot avoid exploding, the battery module is protected by the explosion-proof net to avoid the explosion-caused debris from damaging other external parts due to excessive impact force, causing greater losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural block diagram of the main body of the present invention;

[0017] Figure 2 is a structural diagram of a state detection circuit of the present invention;

[0018] Figure 3 This is an exploded structural diagram of the battery module component of the present invention.

[0019] In the figure: 1. battery module; 2. explosion-proof net; 3. safety valve; 4. thermal conductive silicone sheet; 5. metal shell; 51. mounting hole; 52. ventilation groove; 6. cooling fan; 7. switch unit; 8. charging circuit; 9. status detection circuit; 10. logic control circuit; 91. voltage monitoring module; 92. current monitoring module; 93. temperature monitoring module. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0021] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] See also Figure 1-2 The present invention provides a technical solution: a lithium battery protection system for preventing overcharging, comprising: a battery module 1, a switch unit 7, a logic control circuit 10 and a state detection circuit 9, wherein the switch unit 7 is connected in the charging path of the battery module 1, and one end of the switch unit 7 is connected to the charging circuit 8. The state detection circuit 9 comprises a connected voltage monitoring module 91, a current monitoring module 92 and a temperature monitoring module 93, which are used to detect the state of the battery module 1 and generate a state signal, and the state signal is used to indicate the state of the battery module 1. The logic control circuit 10 receives the state signal from the state detection circuit 9, and controls the switch unit 7 according to the state signal to open and close the charging circuit 8.

[0024] Furthermore, the state detection circuit 9 includes a voltage monitoring module 91 and a current monitoring module 92 connected in parallel to the battery module 1;

[0025] Furthermore, the voltage monitoring module 91 is a high-precision voltage sensor that monitors the voltage level of the battery module 1 in real time. When the battery module 1 is in the charging process, the voltage of the battery module 1 gradually rises and approaches the preset overcharge threshold value, the value of the overcharge threshold value is 4.2V, the voltage monitoring module 91 will immediately send out an overcharge status signal, the logic control circuit 10 controls the switch unit 7 to close after receiving the signal, cuts off the charging circuit 8 to stop the charging process, when the voltage of the battery module 1 drops below the preset undercharge threshold value during the discharge process, the value of the undercharge threshold value is 3V, the voltage monitoring module 91 will automatically identify this state and send out an undercharge status signal, the logic control circuit 10 controls the switch unit 7 to open after receiving the signal, closes the charging circuit 8 to resume charging;

[0026] Furthermore, the current monitoring module 92 is a high-precision current sensor, which monitors the charging current data of the battery module 1 in real time. The current monitoring module 92 compares the collected charging current data with a preset safety threshold. When it is detected that the charging current exceeds the upper limit of the safety threshold, the upper limit of the safety threshold is 1.5C, and the logic control circuit 10 sends a control signal to turn off the switch unit 7 to cut off the charging circuit 8. When it is detected that the charging current is within the preset safety threshold, the logic control circuit 10 sends a control signal to turn on the switch unit 7 to maintain the charging state. When the battery module 1 is fully charged, the charging current drops below the lower limit of the safety threshold, and the lower limit of the safety threshold is 1.5C. This indicates that the battery module 1 has completed the charging process, and the logic control circuit 10 sends a control signal to turn off the switch unit 7 to stop active charging.

[0027] Furthermore, the status detection circuit 9 also includes a temperature monitoring module 93 connected to the battery module 1, and the temperature monitoring module 93 includes a temperature sensor inserted into the battery module 1, and the temperature sensor measures the internal temperature of the battery module 1 in real time. The sensor responds to the temperature change of the battery module 1 and converts the temperature data into an electrical signal. The temperature monitoring module 93 is preset with a temperature threshold, and the temperature threshold includes a high temperature threshold and a low temperature threshold. The temperature threshold is set to 45°C-60°C. When the temperature of the battery module 1 reaches or exceeds the high temperature threshold or is lower than the low temperature threshold, the temperature monitoring module 93 sends a signal to the logic control circuit 10, and the logic control circuit 10 sends a control signal to turn off the switch unit 7 and cut off the charging circuit 8. When the temperature of the battery module 1 returns to between the temperature thresholds, the temperature monitoring module 93 re-sends a signal to the logic control circuit 10, and the logic control circuit 10 sends a control signal to turn on the switch unit 7 to restore the charging circuit 8.

[0028] For further information, see Figure 3The battery module 1 is provided with an explosion-proof device on its shell, and the explosion-proof device includes a safety valve 3 arranged inside the battery module 1 and an explosion-proof net 2 arranged outside the battery module 1. Thermally conductive silicone sheets 4 are fixedly installed on the upper and lower sides of the battery module 1. The shape of the thermally conductive silicone sheets 4 is the same as that of the upper and lower end surfaces of the battery module 1 and is arranged closely to the upper and lower end surfaces of the battery module 1. The outermost part of the battery module 1 is surrounded by a wrapped metal shell 5.

[0029] Furthermore, the safety valve 3 is based on the action of a pressure sensor, which monitors the pressure changes inside the battery module 1 in real time. The safety valve 3 is pre-set with a bursting value. When the internal pressure of the battery module 1 exceeds the bursting value set by the safety valve 3, the bursting value is that the internal pressure of the battery module 1 reaches 1.5MPa. The pressure sensor sends a signal to the safety valve 3. After receiving the signal, the safety valve 3 opens the exhaust port to release the excessive pressure inside the battery module 1. After releasing the excessive pressure, the pressure inside the battery module 1 will gradually decrease to a normal range. When the pressure monitored by the pressure sensor falls below the bursting value, the safety valve 3 automatically closes the exhaust port.

[0030] Furthermore, a mounting hole 51 is provided on one side of the metal shell 5 , a heat dissipation fan 6 is fixedly provided in the mounting hole 51 , and a ventilation groove 52 is penetrated through the end surface of the metal shell 5 on the side where the heat dissipation fan 6 is provided.

[0031] Furthermore, the cooling fan 6 is provided with an electromagnetic switch, and the cooling fan 6 is electrically connected to the temperature monitoring module 93. The temperature monitoring module 93 also presets the upper and lower temperature limits of the cooling fan 6 switch to determine when the cooling fan 6 starts and stops; when the temperature of the battery module 1 exceeds the upper limit value, the temperature monitoring module 93 transmits a signal to the electromagnetic valve to start the cooling fan 6 to lower the temperature of the battery module 1; when the temperature of the battery module 1 reaches or is lower than the lower temperature limit value, the temperature monitoring module 93 transmits a signal to the electromagnetic valve to close the cooling fan 6 to save energy.

[0032] Working principle: The present invention provides a lithium battery protection system to prevent overcharging. The present invention sets a state detection circuit 9 to monitor the state of the battery module 1 in real time. By monitoring the current, voltage, and temperature, the charging state is detected in multiple ways. Once it is detected that the battery is about to be overcharged, the logic control circuit 10 will immediately turn off the switch unit 7 and the charging circuit 8 to avoid the acceleration of the chemical reaction speed inside the battery module 1, prevent the internal pressure of the battery from increasing, and prevent the electrolyte from decomposing and generating gas, thereby causing battery expansion, leakage, and even explosion. The battery module 1 of the present invention is provided with a heat dissipation mechanism, and the heat dissipation fan 6 is in the electric When the battery module 1 is running and generates heat, a ventilation groove 52 is provided at one end of the metal shell 5 to accelerate the circulation of air between the battery module 1 and the metal shell 5 to take away the high heat. At the same time, thermal conductive silicone sheets 4 are provided at the upper and lower ends of the battery module 1 to improve the heat dissipation of the battery module 1 and prevent the battery module 1 from accumulating too much heat and causing thermal runaway. An explosion-proof net 2 is provided on the outside of the battery module 1 in the present invention. When the battery cannot avoid exploding, the explosion-proof net 2 is used to protect the battery module 1 to prevent the explosive chips caused by the explosion from damaging other external parts due to excessive impact force and causing greater losses.

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A lithium battery protection system for preventing overcharging, characterized in that: A battery module (1), a switch unit (7), a logic control circuit (10) and a state detection circuit (9), wherein the switch unit (7) is connected in a charging path of the battery module (1), one end of the switch unit (7) is connected to a charging circuit (8), the state detection circuit (9) comprises a connected voltage monitoring module (91), a current monitoring module (92) and a temperature monitoring module (93), and is used to detect the state of the battery module (1) and generate a state signal, the state signal being used to indicate the state of the battery module (1), the logic control circuit (10) receiving the state signal from the state detection circuit (9), and controlling the switch unit (7) according to the state signal, thereby opening and closing the charging circuit (8).

2. A lithium battery protection system for preventing overcharging according to claim 1, characterized in that: The state detection circuit (9) comprises a voltage monitoring module (91) and a current monitoring module (92) which are connected in parallel to the battery module (1).

3. A lithium battery protection system for preventing overcharging according to claim 2, characterized in that: The voltage monitoring module (91) is a high-precision voltage sensor that monitors the voltage level of the battery module (1) in real time. When the battery module (1) is in the charging process, the voltage of the battery module (1) gradually rises and approaches a preset overcharge threshold value, the voltage monitoring module (91) will immediately send out an overcharge state signal, and after receiving the signal, the logic control circuit (10) controls the switch unit (7) to close, cuts off the charging circuit (8) and stops the charging process. When the voltage of the battery module (1) drops below a preset undercharge threshold value during the discharge process, the voltage monitoring module (91) will automatically identify this state and send out an undercharge state signal, and after receiving the signal, the logic control circuit (10) controls the switch unit (7) to open, closes the charging circuit (8) and resumes charging.

4. A lithium battery protection system for preventing overcharging according to claim 2, characterized in that: The current monitoring module (92) is a high-precision current sensor that monitors the charging current data of the battery module (1) in real time. The current monitoring module (92) compares the collected charging current data with a preset safety threshold. When it is detected that the charging current exceeds the upper limit of the safety threshold, the logic control circuit (10) sends a control signal to close the switch unit (7) and cut off the charging circuit (8). When it is detected that the charging current is within the preset safety threshold, the logic control circuit (10) sends a control signal to open the switch unit (7) to maintain the charging state. When the battery module (1) is fully charged and the charging current drops below the lower limit of the safety threshold, the logic control circuit (10) sends a control signal to close the switch unit (7) to stop active charging.

5. The lithium battery protection system for preventing overcharging according to claim 2, characterized in that: The state detection circuit (9) further comprises a temperature monitoring module (93) connected to the battery module (1), wherein the temperature monitoring module (93) comprises a temperature sensor inserted into the battery module (1), wherein the temperature sensor measures the internal temperature of the battery module (1) in real time, wherein the sensor responds to the temperature change of the battery module (1) and converts the temperature data into an electrical signal, wherein the temperature monitoring module (93) is preset with a temperature threshold, wherein the temperature threshold comprises a high temperature threshold and a low temperature threshold, wherein when the temperature of the battery module (1) reaches or exceeds the high temperature threshold or is lower than the low temperature threshold, the temperature monitoring module (93) sends a signal to the logic control circuit (10), wherein the logic control circuit (10) sends a control signal to close the switch unit (7) and cut off the charging circuit (8), and when the temperature of the battery module (1) returns to between the temperature thresholds, the temperature monitoring module (93) sends a signal to the logic control circuit (10) again, wherein the logic control circuit (10) sends a control signal to open the switch unit (7) and restore the charging circuit (8).

6. The lithium battery protection system for preventing overcharging according to claim 1, characterized in that: The battery module (1) is provided with an explosion-proof device on its shell, the explosion-proof device comprising a safety valve (3) arranged inside the battery module (1) and an explosion-proof net (2) arranged outside the battery module (1); thermally conductive silicone sheets (4) are fixedly mounted on the upper and lower sides of the battery module (1); the shape of the thermally conductive silicone sheets (4) is the same as that of the upper and lower end surfaces of the battery module (1) and is arranged in close contact with the upper and lower end surfaces of the battery module (1); and a metal shell (5) is provided around the outermost periphery of the battery module (1).

7. A lithium battery protection system for preventing overcharging according to claim 6, characterized in that: The safety valve (3) is based on the action of a pressure sensor, which monitors the pressure changes inside the battery module (1) in real time. The safety valve (3) is pre-set with a burst value. When the internal pressure of the battery module (1) exceeds the burst value set by the safety valve (3), the pressure sensor sends a signal to the safety valve (3). After receiving the signal, the safety valve (3) opens the exhaust port to release the excessive pressure inside the battery module (1). After the excessive pressure is released, the pressure inside the battery module (1) will gradually decrease to a normal range. When the pressure monitored by the pressure sensor falls below the burst value, the safety valve (3) automatically closes the exhaust port.

8. The lithium battery protection system for preventing overcharging according to claim 6, characterized in that: A mounting hole (51) is provided on one side of the metal shell (5), a heat dissipation fan (6) is fixedly provided in the mounting hole (51), and a ventilation groove (52) is provided through the end surface of the metal shell (5) on the side opposite to the heat dissipation fan (6).

9. A lithium battery protection system for preventing overcharging according to claim 8, characterized in that: The heat dissipation fan (6) is provided with an electromagnetic switch, and the heat dissipation fan (6) is electrically connected to a temperature monitoring module (93). The temperature monitoring module (93) is also preset with upper and lower temperature limits of the heat dissipation fan (6) switch to determine when the heat dissipation fan (6) is started and stopped; when the temperature of the battery module (1) exceeds the upper limit value, the temperature monitoring module (93) transmits a signal to the electromagnetic valve to start the heat dissipation fan (6) to reduce the temperature of the battery module (1); when the temperature of the battery module (1) reaches or is lower than the lower limit value of the temperature, the temperature monitoring module (93) transmits a signal to the electromagnetic valve to close the heat dissipation fan (6) to save energy.

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