A thermal management circuit and battery pack

Abstract

The utility model relates to a kind of thermal management circuit and battery pack, and the thermal management circuit includes fuse, N detection circuits, drive circuit and switch circuit, each detection circuit corresponds with electric core one to one, detection circuit is used to detect the temperature of electric core and generates the detection voltage that is positively correlated with the temperature of electric core, drive circuit is also electrically connected with the control end of switch circuit, switch circuit is also electrically connected with the control end of fuse and ground respectively, fuse is electrically connected between adjacent battery module.When detection voltage is greater than voltage threshold, drive circuit generates control signal, so that the electrical connection between the control end of switch circuit and ground of fuse is connected, fuse is fused, and then the electrical connection between adjacent battery module is disconnected, to disconnect power loop.The thermal management circuit detects the temperature of each electric core in battery module, detection is more accurate, and any electric core temperature anomaly will be promptly cut off power loop, and the safety is higher.

Description

Technical Field

[0001] This utility model relates to the field of thermal management circuits, and in particular to a thermal management circuit and a battery pack. Background Technology

[0002] Thermal runaway refers to an accident that occurs when an electrochemical battery raises its temperature uncontrollably through self-heating. Thermal runaway happens when the heat generated by the battery pack exceeds its ability to dissipate heat. After thermal runaway occurs, high-voltage arcing may occur, or even fire, explosion, and gas release, resulting in poor battery pack safety.

[0003] The battery pack employs a thermal management circuit to detect thermal runaway and disconnect the power circuit in the event of runaway to prevent fires, explosions, or other incidents. However, current thermal management circuits only disconnect the power circuit when the battery module reaches its thermal runaway temperature threshold. If one cell experiences thermal runaway, the entire battery module may not reach the threshold, failing to effectively disconnect the power circuit. This results in continuous high-current heating and a continued rise in temperature, potentially leading to fires or explosions, thus compromising the battery pack's safety. Utility Model Content

[0004] The present invention aims to provide a thermal management circuit and a battery pack that can improve the safety of the battery pack.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solutions:

[0006] In a first aspect, this utility model provides a thermal management circuit applied to a battery pack, the battery pack including a battery module, the battery module including cells connected in series and / or in parallel, the thermal management circuit including a fuse, N detection circuits, a drive circuit and a switching circuit, wherein N is the number of cells;

[0007] Each of the detection circuits corresponds one-to-one with the battery cell, and the first terminal of each detection circuit is used to connect to the first power supply. The second terminal of each detection circuit is electrically connected to the first node together with the driving circuit. The detection circuit is configured to detect the temperature of the battery cell and generate a detection voltage, wherein the detection voltage is positively correlated with the temperature of the battery cell.

[0008] The driving circuit is also electrically connected to the control terminal of the switching circuit, and the driving circuit is configured to generate a control signal in response to the result that the detected voltage is greater than the voltage threshold.

[0009] The switching circuit is also connected to the control terminal of the fuse and ground, and the fuse is electrically connected between adjacent battery modules;

[0010] The switching circuit is used to respond to the input of the control signal, connect the control terminal of the fuse to ground, so that the fuse blows and disconnects the electrical connection between the adjacent battery modules.

[0011] In some embodiments, the driving circuit includes a first voltage regulator unit and a signal generation unit;

[0012] The first voltage regulator unit is electrically connected to the control terminal of the first node and the signal generation unit, respectively; the signal generation unit is electrically connected to the control terminal of the second power supply and the switching circuit, respectively.

[0013] The first voltage regulator unit is configured to generate a first voltage regulator signal in response to the result that the detected voltage is greater than the voltage threshold, so as to control the signal generation unit to generate the control signal based on the second power supply.

[0014] In some embodiments, the signal generation unit includes a first switching unit, a first voltage divider unit, a second switching unit, and a second voltage divider unit;

[0015] The control terminal of the first switching unit is electrically connected to the first voltage regulator unit. The first switching unit is connected to the first voltage divider unit and ground. The first voltage divider unit is also electrically connected to the second power supply and the control terminal of the second switching unit. The second switching unit is also electrically connected to the second power supply and the second voltage divider unit. The second voltage divider unit is also electrically connected to the switching circuit.

[0016] The first switching unit is configured to respond to the input of the first regulated signal by connecting the electrical connection between the first voltage divider unit and ground, so that the first voltage divider unit divides the second power supply to generate the first voltage divider signal;

[0017] The second switching unit is configured to respond to the input of the first voltage divider signal by connecting the electrical connection between the second power supply and the second voltage divider unit, so that the second voltage divider unit divides the second power supply to generate the control signal.

[0018] In some embodiments, the first voltage regulator unit includes a first Zener diode, the first switching unit includes a first resistor, a second resistor and a first transistor, the first voltage divider unit includes a third resistor and a fourth resistor, the second switching unit includes a second transistor, and the second voltage divider unit includes a fifth resistor and a sixth resistor.

[0019] The cathode of the first Zener diode is electrically connected to the first node, the anode of the first Zener diode is electrically connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor and the base of the first transistor, the other end of the second resistor and the emitter of the first transistor are grounded together, the collector of the first transistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the fourth resistor and the base of the second transistor, the other end of the fourth resistor and the emitter of the second transistor are both used to connect to the second power supply, the collector of the second transistor is connected to one end of the fifth resistor, the other end of the fifth resistor is electrically connected to one end of the sixth resistor and the control terminal of the switching circuit.

[0020] In some embodiments, the driving circuit further includes N unidirectional conduction circuits, each of which is electrically connected between the second terminal of the corresponding detection circuit and the first node, and the unidirectional conduction circuit is configured to prevent reverse current from flowing into the detection circuit.

[0021] In some embodiments, the driving circuit further includes a power conversion unit, which is electrically connected to a third power supply and the signal generation unit, respectively.

[0022] The power conversion unit is configured to perform voltage conversion on the third power supply to obtain the second power supply.

[0023] In some embodiments, the power conversion unit includes a second voltage regulator unit and a third switching unit;

[0024] The second voltage regulator unit is electrically connected to the control terminals of the third power supply and the third switching unit, respectively. The second voltage regulator unit is configured to generate a second voltage regulator signal in response to the input of the third power supply.

[0025] The first end of the third switching unit is electrically connected to the third power supply, and the second end of the third switching unit is electrically connected to the signal generation unit at the second node. The third switching unit is configured to generate the second power supply in response to the input of the second regulated signal and the third power supply.

[0026] In some embodiments, the power conversion unit further includes a third voltage regulation unit and a filtering unit;

[0027] The third voltage regulator unit and the filter unit are both electrically connected to the second node. The third voltage regulator unit is configured to regulate the voltage of the second power supply, and the filter unit is configured to filter the second power supply.

[0028] In some embodiments, the detection circuit includes a heat-conducting element, a thermistor, and a voltage divider resistor. The two ends of the heat-conducting element are respectively attached to the end face of the battery cell and the thermistor to conduct the heat of the battery cell from one end of the heat-conducting element to the thermistor connected to the other end. One end of the thermistor is also electrically connected to the first power supply, and the other end of the thermistor is connected to one end of the voltage divider resistor and the first node. The other end of the voltage divider resistor is grounded.

[0029] In a second aspect, embodiments of the present invention provide a battery pack, the battery pack including a battery module and a thermal management circuit as described above, wherein the battery module includes cells connected in series and / or in parallel.

[0030] In various embodiments of this utility model, the thermal management circuit includes a fuse, N detection circuits, a drive circuit, and a switching circuit, where N is the number of battery cells. Each detection circuit corresponds one-to-one with a battery cell, and the first terminal of each detection circuit is used to connect to a first power supply. The second terminal of each detection circuit is electrically connected to a first node together with the drive circuit. The drive circuit is also electrically connected to the control terminal of the switching circuit. The switching circuit is also electrically connected to the control terminal of the fuse and ground. The fuse is electrically connected between adjacent battery modules. The detection circuit detects the temperature of the battery cell and generates a detection voltage. The detection voltage is positively correlated with the temperature of the battery cell. When the detection voltage is greater than a voltage threshold, it indicates that the current temperature of the battery cell exceeds the temperature of the battery cell corresponding to the voltage threshold, indicating an abnormal temperature. The drive circuit generates a control signal, causing the switching circuit to connect the control terminal of the fuse to ground. The second battery module, the fuse, the switching circuit, and ground form a closed loop. A large current flows through the fuse, causing the fuse to melt and break the electrical connection between adjacent battery modules, thus disconnecting the power circuit.

[0031] Therefore, this thermal management circuit detects the temperature of the cells in the battery module. When the temperature of a cell is abnormal, it controls the fuse to blow, thereby disconnecting the electrical connection between adjacent battery modules, disconnecting the power circuit, reducing the risk of thermal runaway or battery explosion, and improving the safety of the battery pack. Compared with related technologies that only detect the temperature of one battery module, this thermal management circuit detects the temperature of each cell in the battery module, making the detection more accurate. If the temperature of any cell is abnormal, the power circuit will be cut off in time, resulting in higher safety. Attached Figure Description

[0032] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0033] Figure 1 This is a schematic diagram of the structure of a battery pack provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of a battery management circuit provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of a driving circuit provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the circuit structure of a thermal management circuit provided in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0038] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a battery pack provided in an embodiment of this utility model, as shown below. Figure 1 As shown, the battery pack includes a thermal management circuit 100 and battery modules 200, and there can be multiple battery modules 200. Multiple battery modules 200 can be connected in series, parallel, or a combination thereof. If the battery modules 200 are connected in series, the positive and negative terminals of the battery pack are the positive terminal of the first battery module 200 and the negative terminal of the last battery module 200, respectively. If the battery modules 200 are connected in parallel, the positive terminals of all battery modules 200 are connected together as the positive terminal of the battery pack, and the negative terminals of all battery modules 200 are connected together as the negative terminal of the battery pack.

[0039] The battery module 200 includes multiple cells connected in series, parallel, or a hybrid configuration for storing and providing electrical energy. Hybrid configurations include both series and parallel connections. If the cells in the battery module 200 are connected in series, the negative terminal of the previous cell is connected to the positive terminal of the next cell. After sequential connection, the exposed terminals of the battery module 200 are the positive terminal of the first cell and the negative terminal of the last cell, respectively, which become the positive and negative terminals of the battery module 200. If the cells in the battery module 200 are connected in parallel, the positive terminals of all cells are connected together to form the positive terminal of the battery module 200, and the negative terminals of all cells are connected together to form the negative terminal of the battery module 200.

[0040] Thermal runaway occurs when the heat generated by a battery pack exceeds its heat dissipation capacity. After thermal runaway, due to insulation failure caused by heat and the ejection of conductive metal debris, frequent high-voltage arcing occurs within the battery pack. This can lead to risks such as battery pack cover breakdown, overcurrent temperature rise, and cell breakdown failure. It also causes severe heat propagation within the battery pack, generating a large amount of heat, causing a rapid rise in battery pack temperature, and potentially resulting in fire, explosion, and gas release, thus compromising battery pack safety.

[0041] The battery pack employs a thermal management circuit to detect thermal runaway and disconnect the power circuit in the event of thermal runaway to prevent fires, explosions, or other incidents. The thermal management circuit in this technology includes a fuse and a temperature control switch. The fuse is connected between battery modules, and the temperature control switch is fixed to a cell within the battery module. The temperature control switch is electrically connected to the control terminal of the fuse. When a single cell experiences thermal runaway, the temperature exceeds 200°C. The temperature control switch activates, changing from normally open to normally closed, which in turn activates the control terminal of the fuse. This heats the internal heating element of the fuse, melting the main circuit and disconnecting the power circuit, thus ensuring that the power PCBA board is not energized and consequently, the entire power PCBA is de-energized.

[0042] However, the temperature control switches in the thermal management circuits of related technologies cannot collect the temperature of each individual cell in a timely manner. Only when the temperature of the battery module reaches the thermal runaway temperature threshold will the temperature control switch fixed to that battery module activate, thus cutting off the power circuit. If one cell experiences thermal runaway, the temperature of the entire battery module may not have reached the thermal runaway temperature threshold, and the power circuit may not be effectively cut off. The power circuit continues to generate high current and heat, causing the temperature to rise continuously. The PCB board containing the power circuit may carbonize and catch fire. Furthermore, the thermally runaway cell may eject electrolyte, potentially leading to an explosion. Therefore, the inaccurate temperature detection of the cells in these technologies results in a higher risk of thermal runaway in the battery pack, leading to a higher risk of fire, explosion, and other phenomena, thus reducing the overall safety of the battery pack.

[0043] To address the aforementioned issues, this utility model provides a thermal management circuit 100 that can accurately detect the temperature of each battery cell, promptly disconnect the power circuit, and improve the safety of the battery pack.

[0044] Specifically, such as Figure 2As shown, the thermal management circuit 100 includes a fuse 40, N detection circuits 10, a drive circuit 20, and a switching circuit 30, where N is the number of battery cells, and each detection circuit 10 corresponds one-to-one with a battery cell. Each battery module 200 corresponds to one thermal management circuit 100. In the following embodiments, the operation of the thermal management circuit 100 is described using the example of a battery module 200 including an adjacent first battery module 201 and a second battery module 202, and the connection relationship of the thermal management circuit 100 is described using the thermal management circuit 100 corresponding to the first battery module 201 as an example.

[0045] The first detection circuit 10 corresponds to the first battery cell (represented by a dashed line in the diagram) and is used to detect the temperature of the first battery cell and generate a corresponding detection voltage. The second detection circuit 10 corresponds to the second battery cell and is used to detect the temperature of the second battery cell and generate a corresponding detection voltage. And so on, the Nth detection circuit 10 corresponds to the Nth battery cell and is used to detect the temperature of the Nth battery cell and generate a corresponding detection voltage.

[0046] Furthermore, the first terminal of each detection circuit 10 is used to connect to the first power supply, and the second terminal of each detection circuit 10 is electrically connected to the first node a along with the driving circuit 20. The detection circuit 10 generates a corresponding detection voltage based on the temperature of the first power supply and the battery cell. The detection voltage is positively correlated with the temperature of the battery cell, that is, the higher the temperature of the battery cell, the greater the detection voltage. The detection voltage increases as the temperature of the battery cell rises. The temperature of one battery cell corresponds to a value of one detection voltage. For example, if the temperature of the battery cell is T1, the detection voltage is V1; if the temperature of the battery cell is T2, the detection voltage is V2, and so on. The value of the detection voltage represents the temperature of the battery cell.

[0047] The drive circuit 20 is also electrically connected to the control terminal of the switch circuit 30. The switch circuit 30 is also electrically connected to the control terminal of the fuse 40 and ground. The working state of the switch circuit 30 controls the connection between the control terminal of the fuse 40 and ground. If the working state of the switch circuit 30 is the on state, the control terminal of the fuse 40 is connected to ground. If the working state of the switch circuit 30 is the off state, the control terminal of the fuse 40 is disconnected from ground.

[0048] The switching circuit 30 can be various controllable switches such as relays or IGBTs, depending on the specific application scenario. The switching circuit 30 can receive control signals at its control terminal, which can control the switching circuit 30 to turn on or off.

[0049] Fuse 40 is electrically connected between adjacent battery modules, such as Figure 2As shown, fuse 40 is connected between the first battery module 201 and the second battery module 202. If the first battery module 201 and the second battery module 202 are connected in series, fuse 40 is electrically connected between the negative terminal of the first battery module 201 and the positive terminal of the second battery module 202. If the first battery module 201 and the second battery module 202 are connected in parallel, fuse 40 is electrically connected between the positive terminal of the first battery module 201 and the positive terminal of the second battery module 202 (not shown in the figure). If fuse 40 blows, the electrical connection between the first battery module 201 and the second battery module 202 is broken, and thus the power circuit is disconnected.

[0050] The detection voltage of each detection circuit 10 is output to the first node a to drive the drive circuit 20. When the detection voltage is greater than the voltage threshold, it indicates that the current temperature of the battery cell exceeds the temperature threshold corresponding to the voltage threshold, indicating an abnormal temperature. The drive circuit 20 generates a control signal based on the detection voltage, which puts the switch circuit 30 into a conducting state, thereby connecting the control terminal of the fuse 40 to the ground. The positive terminal of the second battery module 202, the fuse 40, the switch circuit 30, and the ground form a closed loop. A large current flows through the fuse 40, and the heating wire in the fuse 40 melts, thereby disconnecting the electrical connection between the first battery module 201 and the second battery module 202 and disconnecting the power circuit.

[0051] Furthermore, if the temperature of any cell exceeds the temperature threshold, the detection voltage generated by the corresponding detection circuit 10 will be greater than the voltage threshold, which will cause the fuse 40 to blow and disconnect the power circuit, ensuring that the power circuit can be disconnected in time when any cell experiences thermal runaway.

[0052] Therefore, this thermal management circuit detects the temperature of the cells in the battery module. When the temperature of a cell is abnormal, it controls the fuse to blow, thereby disconnecting the electrical connection between adjacent battery modules and disconnecting the power circuit. This reduces the risk of thermal runaway or battery explosion and improves the safety of the battery pack. Compared with related technologies that only detect the temperature of one battery module, this thermal management circuit detects the temperature of each cell in the battery module, making the detection more accurate. If the temperature of any cell is abnormal, the power circuit will be cut off in time, resulting in higher safety.

[0053] In some embodiments, please continue reading Figure 2The thermal management circuit 100 further includes N unidirectional conduction circuits 50, each of which is electrically connected between the second terminal of the corresponding detection circuit 10 and the first node a. For example, the first unidirectional conduction circuit 50 is electrically connected between the second terminal of the first detection circuit 10 and the first node a, the second unidirectional conduction circuit 50 is electrically connected between the second terminal of the second detection circuit 10 and the first node a, and so on, with the Nth unidirectional conduction circuit 50 being electrically connected between the second terminal of the Nth detection circuit 10 and the first node a.

[0054] The unidirectional conduction circuit 50 only allows unidirectional conduction. The detection voltage can be output to the first node a through the unidirectional conduction circuit 50, while other reverse currents at the first node a cannot flow into the detection circuit 10 through the unidirectional conduction circuit 50. This prevents reverse current or other voltages from flowing back into the detection circuit 10, ensuring that the detection voltage is not affected by other voltages or other currents, and improving detection accuracy.

[0055] Please see Figure 3 , Figure 3 This is a schematic diagram of a driving circuit provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the driving circuit 20 includes a first voltage regulator unit 21 and a signal generation unit 22. The first voltage regulator unit 21 is electrically connected to the first node a and the control terminal of the signal generation unit 22, respectively. The signal generation unit 22 is electrically connected to the second power supply and the control terminal of the switching circuit 30, respectively.

[0056] When the detected voltage exceeds the voltage threshold, the first voltage regulator unit 21 generates a first regulated voltage signal based on the input of the detected voltage, and the first regulated voltage signal control signal generation unit 22 generates a control signal based on the second power supply. This control signal controls the switching circuit 30 to be in the conducting state, causing the fuse 40 to blow, thereby disconnecting the power circuit.

[0057] When the detected voltage is greater than the voltage threshold, the first voltage regulator unit 21 is used to ensure that the signal generation unit 22 can generate a control signal based on the second power supply, thereby ensuring that the fuse 40 blows and the power circuit is disconnected.

[0058] In some embodiments, please continue reading Figure 3 The signal generation unit 22 includes a first switching unit 221, a first voltage divider unit 222, a second switching unit 223, and a second voltage divider unit 224. The control terminal of the first switching unit 221 is electrically connected to the first voltage regulator unit 21. The first switching unit 221 is also connected to the first voltage divider unit 222 and ground. The first voltage divider unit 222 is also electrically connected to the second power supply and the control terminal of the second switching unit 223. The second switching unit 223 is also electrically connected to the second power supply and the second voltage divider unit 224. The second voltage divider unit 224 is also electrically connected to the switching circuit 30.

[0059] Both the first switching unit 221 and the second switching unit 223 can be various controllable switches such as relays or IGBTs, and the specific type can be determined according to the actual application scenario. Both the first switching unit 221 and the second switching unit 223 can change their operating state based on the signal received from their control terminals, such as turning on or off based on the signal received from their control terminals.

[0060] In response to the input of the first regulated voltage signal, the first switching unit 221 connects the first voltage divider unit 222 to ground, causing the first voltage divider unit 222 to divide the second power supply and generate a first voltage divider signal. This first voltage divider signal is output to the control terminal of the second switching unit 223, causing the second switching unit 223 to be in a conducting state. This connects the second power supply to the second voltage divider unit 224, which then divides the second power supply to generate a control signal. The control signal controls the switching circuit 30 to be in a conducting state, causing the fuse 40 to blow, disconnecting the electrical connection between the first battery module 201 and the second battery module 202, and disconnecting the power circuit.

[0061] This embodiment employs a dual-switch design with a first switch unit 221 and a second switch unit 223, which enables the reliable generation of a control signal when the first regulated signal is input, thereby reliably controlling the switch circuit 30 to conduct, improving the reliability of the fuse 40 to blow, and thus improving the safety of the battery pack.

[0062] In some embodiments, please continue reading Figure 3 The driving circuit 20 also includes a power conversion unit 23, which is electrically connected to the third power supply and the signal generation unit 22.

[0063] The power conversion unit 23 performs voltage conversion on the third power supply to obtain the second power supply. In some embodiments, the power conversion unit 23 performs voltage reduction and stabilization processing on the voltage of the third power supply to obtain the voltage of the second power supply.

[0064] The third power source can be provided by an independent power source or by the negative terminal of the first battery module 201. Specifically, the negative terminal of the first battery module 201 is electrically connected to the power conversion unit 23, and the voltage between the negative terminal of the first battery module 201 and the negative terminal of the battery pack is within a certain voltage range. The power conversion unit 23 generates the voltage of the second power source based on this voltage range. If the third power source is provided by the negative terminal of the first battery module 201, it saves power, reduces circuit costs, simplifies the wiring, eliminates the need for other power sources, and reduces interference.

[0065] In some embodiments, please continue reading Figure 3The power conversion unit 23 includes a second voltage regulator unit 231 and a third switch unit 232. The second voltage regulator unit 231 is electrically connected to the control terminals of the third power supply and the third switch unit 232, respectively. The first terminal of the third switch unit 232 is electrically connected to the third power supply, and the second terminal of the third switch unit 232 is electrically connected to the signal generation unit 22 at the second node b.

[0066] The third switching unit 232 can be various controllable switches such as relays or IGBTs, and the specific type can be determined according to the actual application scenario. This third switching unit 232 can change its operating state based on the signal received from its control terminal, such as turning it on or off based on the signal received from its control terminal.

[0067] The second voltage regulator unit 231 generates a second regulated voltage signal based on the third power supply. The voltage of the second regulated voltage signal is a stable voltage. The second regulated voltage signal is output to the control terminal of the third switching unit 232. The third switching unit 232 is in the conducting state, connecting the electrical connection between the third power supply and the signal generation unit 22. The third switching unit 232 obtains the voltage of the second power supply at the second node b based on the voltage of the third power supply and the voltage of the second regulated voltage signal.

[0068] In some embodiments, please continue reading Figure 3 The power conversion unit 23 also includes a third voltage regulator unit 233 and a filter unit 234. The third voltage regulator unit 233 and the filter unit 234 are both electrically connected to the second node b. The third voltage regulator unit 233 regulates the voltage of the second power supply, and the filter unit 234 filters the second power supply.

[0069] A third voltage regulator unit 233 is used to perform secondary voltage regulation on the second power supply to prevent the inability to stably generate the voltage of the second power supply when the second voltage regulator unit 231 fails, thereby improving the reliability of generating the second power supply. A filter unit 234 is used to filter the second power supply, remove ripple, and perform voltage regulation again, which can slow down the voltage change rate at the control terminal of the switching circuit 30 and prevent the transient voltage change at the control terminal of the switching circuit 30 from causing power failure due to excessively rapid change.

[0070] Please see Figure 4 , Figure 4 This is a schematic diagram of the circuit structure of a thermal management circuit provided in an embodiment of this utility model, as shown below. Figure 4 As shown, the first voltage regulator unit 21 includes a first voltage regulator diode DZ1. The cathode of the first voltage regulator diode DZ1 is electrically connected to the first node a, and the anode of the first voltage regulator diode DZ1 is electrically connected to the control terminal of the signal generation unit 22.

[0071] The first switching unit 221 includes a first resistor R1, a second resistor R2 and a first transistor Q1, the first voltage divider unit 222 includes a third resistor R3 and a fourth resistor R4, the second switching unit 223 includes a second transistor Q2, and the second voltage divider unit 224 includes a fifth resistor R5 and a sixth resistor R6.

[0072] One end of the first resistor R1 is electrically connected to the first voltage regulator unit 21. Specifically, one end of the first resistor R1 is connected to the anode of the first Zener diode DZ1. The other end of the first resistor R1 is connected to one end of the second resistor R2 and the base of the first transistor Q1. The other end of the second resistor R2 is grounded together with the emitter of the first transistor Q1. The collector of the first transistor Q1 is connected to one end of the third resistor R3. The other end of the third resistor R3 is connected to one end of the fourth resistor R4 and the base of the second transistor Q2. The other end of the fourth resistor R4 and the emitter of the second transistor Q2 are both used to connect to the second power supply. The collector of the second transistor Q2 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is electrically connected to one end of the sixth resistor R6 and the control terminal of the switching circuit 30.

[0073] Each unidirectional conduction circuit 50 includes a diode, wherein the anode of the diode is electrically connected to the corresponding detection circuit 10, and the cathodes of all diodes are connected to the first node a. There are N unidirectional conduction circuits 50. Figure 4 Taking N=8 as an example, the first unidirectional conducting circuit 50 includes diode D1, the second unidirectional conducting circuit 50 includes diode D2, and so on, with the eighth unidirectional conducting circuit 50 including diode D8.

[0074] The second voltage regulator unit 231 includes a seventh resistor R7, a second Zener diode DZ2, and a first capacitor C1. The third switching unit 232 includes an eighth resistor R8 and a third transistor Q3. One end of the seventh resistor R7 is electrically connected to one end of the eighth resistor R8 and the third power supply. The other end of the seventh resistor R7 is connected to the cathode of the second Zener diode DZ2, one end of the first capacitor C1, and the base of the third transistor Q3. The anode of the second Zener diode DZ2 and the other end of the first capacitor C1 are grounded together. The emitter of the third transistor Q3 is electrically connected to the second node b.

[0075] The third voltage regulator unit 233 includes a third Zener diode DZ3, and the filter unit 234 includes a second capacitor C2 and a third capacitor C3. The cathode of the third Zener diode DZ3, one end of the second capacitor C2, and one end of the third capacitor C3 are all connected to the second node b. The anode of the third Zener diode DZ3, the other end of the second capacitor C2, and the other end of the third capacitor C3 are all grounded.

[0076] The detection circuit 10 also includes a heat-conducting element (not shown in the figure), a thermistor, and a voltage divider resistor, wherein the number of the heat-conducting element, the thermistor, and the voltage divider resistor are all N. Figure 4 Taking N=8 as an example, the first detection circuit 10 includes a thermistor RT2 and a voltage divider resistor R8, the second detection circuit 10 includes a thermistor RT3 and a voltage divider resistor R12, the third detection circuit 10 includes a thermistor RT4 and a voltage divider resistor R13, and so on, with the eighth detection circuit 10 including a thermistor RT9 and a voltage divider resistor R18.

[0077] A heat-conducting component is located at the end of each battery cell. The two ends of the heat-conducting component are respectively attached to the end face of the battery cell and a thermistor. The heat-conducting component is designed to match the shape of the battery cell end, ensuring good contact between the heat-conducting component and the battery cell, allowing the heat-conducting component to quickly absorb the heat generated by the battery cell. The heat-conducting component is a good conductor of heat, capable of conducting the heat from one end of the heat-conducting component to the thermistor connected to the other end. The thermistor can then be used to directly measure the temperature of the battery cell.

[0078] The thermistor is a negative temperature coefficient thermistor, also known as an NTC thermistor, which is a type of sensor resistor whose resistance decreases as temperature increases. One end of the thermistor is also electrically connected to the first power supply, and the other end of the thermistor is connected to one end of the voltage divider resistor and the anode of the corresponding diode. The cathode of the diode is connected to the first node a, and the other end of the voltage divider resistor is grounded.

[0079] The switching circuit 30 includes a MOSFET Q4, a fourth capacitor C4, and a ninth resistor R9. The gate of the MOSFET Q4 is electrically connected to the driving circuit 20. Specifically, the gate of the MOSFET Q4 is connected to the fifth resistor R5 and the sixth resistor R6, respectively. The drain of the MOSFET Q4 is electrically connected to one end of the fourth capacitor C4 and the control terminal of the fuse 40, respectively. The other end of the fourth capacitor C4 is connected to one end of the ninth resistor R9, and the source of the MOSFET Q4 and the other end of the ninth resistor R9 are grounded together.

[0080] In some embodiments, the drain of MOSFET Q4 is connected to the control terminal of fuse 40 via an interface, connector, or socket, such as... Figure 4 As shown, the drain of MOSFET Q4 is connected to the negative terminal of socket CN1, and the control terminal of fuse 40 is connected to the positive terminal of socket CN1. Socket CN1 can connect the control terminal of fuse 40 to the PCBA board.

[0081] In this embodiment, the third power source is provided by the negative terminal BAT_1- of the first battery module, which is connected to the seventh resistor R7 and the eighth resistor R8. Fuse 40 is connected between the negative terminal BAT_1- of the first battery module and the positive terminal BAT_2+ of the second battery module.

[0082] Combination Figure 4 The working principle of the thermal management circuit 100 can be described as follows:

[0083] The voltage between the negative terminal of the first battery module 201 and the negative terminal of the battery pack is within a certain voltage range, such as 22.4V-29V. This voltage range is regulated by the second Zener diode DZ2 to generate a second regulated signal, the voltage of which is the regulated voltage value of the second Zener diode DZ2. This second regulated signal turns on the third transistor Q3. Based on the voltage of the third power supply and the voltage of the second regulated signal, the third transistor Q3 steps down the voltage of the third power supply, which is then further regulated by the third Zener diode DZ3. At point b, the second power supply is obtained, and its voltage is the regulated voltage value of the third Zener diode DZ3. Simultaneously, the third Zener diode DZ3 further regulates the voltage to prevent subsequent stages from failing if the second Zener diode DZ2 fails, ensuring reliable generation of the second power supply and thus providing reliable over-temperature protection for the battery cell. Both the second capacitor C2 and the third capacitor C3 regulate their input voltage to prevent the gate voltage of the MOSFET Q4 from changing too rapidly, which could lead to power loss.

[0084] Each temperature of the battery cell corresponds one-to-one with the resistance value of a thermistor. The thermistor and voltage-dividing resistors divide the voltage of the primary power supply to obtain the detection voltage. Different battery cell temperatures correspond to different thermistor resistance values, thus generating different detection voltages. As the battery cell temperature increases, the thermistor resistance decreases, and the detection voltage increases. When the battery cell temperature gradually rises to a temperature threshold, for example, 105°C, the detection voltage reaches the voltage threshold. When the battery cell temperature exceeds the temperature threshold, the detection voltage exceeds the voltage threshold.

[0085] When any of the detected voltages exceeds the voltage threshold, the detected voltage is output to the first Zener diode DZ1 through the corresponding diode. The first Zener diode DZ1 is turned on and generates a first regulated voltage signal. The voltage of the first regulated voltage signal is the regulated voltage value of the first Zener diode DZ1. The first regulated voltage signal turns on the first transistor Q1. Then, the fourth resistor R4 and the third resistor R3 divide the second power supply to obtain the first voltage divider signal. The first voltage divider signal turns on the second transistor Q2. Then, the fifth resistor R5 and the sixth resistor R6 divide the second power supply to obtain the corresponding voltage divider signal. This voltage divider signal serves as the control signal for the MOSFET Q4, acting on the gate of the MOSFET Q4 to control the MOSFET Q4 to turn on. Then, the positive terminal of the second battery module 202, the fuse 40, the interface CN1, the MOSFET Q4, and ground form a closed loop. A large current flows through the heating wire of the fuse 40, causing the heating wire of the fuse 40 to heat up and melt, breaking the electrical connection between the first battery module 201 and the second battery module 202, thereby disconnecting the power circuit.

[0086] The voltage of the first power supply, the resistance of the voltage divider resistor, and the voltage regulation value of each Zener diode can all be set as needed. In this embodiment, the voltage of the first power supply is +5V, the resistance of the voltage divider resistor is 10K, the voltage regulation value of the first Zener diode DZ1 is 3.9V, the voltage regulation value of the second Zener diode DZ2 is 18V, and the voltage regulation value of the third Zener diode DZ3 is 12V. Therefore, the voltage of the second power supply is 12V.

[0087] The second resistor R2 also acts as a pull-down resistor, ensuring that the gate of the first transistor Q1 is stably pulled low when the entire circuit is not in operation. The ninth resistor R9 and the fourth capacitor C4 form an RC snubber circuit to prevent damage caused by static electricity during plugging and unplugging.

[0088] In summary, this thermal management circuit detects the temperature of the cells in the battery module. When a cell's temperature is abnormal, it controls the fuse to blow, disconnecting the electrical connection between adjacent battery modules and breaking the power circuit. This reduces the risk of thermal runaway or battery explosion and improves the safety of the battery pack. Compared to related technologies that only detect the temperature of one battery module, this thermal management circuit detects the temperature of each cell in the battery module, making the detection more accurate. If any cell's temperature is abnormal, the power circuit will be cut off in time, resulting in higher safety.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this utility model as described above, which are not provided in detail for the sake of brevity; 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; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A thermal management circuit, characterized in that, The application is to a battery pack, the battery pack including a battery module, the battery module including cells connected in series and / or in parallel, the thermal management circuit including a fuse, N detection circuits, a drive circuit and a switching circuit, wherein N is the number of cells; Each of the detection circuits corresponds one-to-one with the battery cell, and the first terminal of each detection circuit is used to connect to the first power supply. The second terminal of each detection circuit is electrically connected to the first node together with the driving circuit. The detection circuit is configured to detect the temperature of the battery cell and generate a detection voltage, wherein the detection voltage is positively correlated with the temperature of the battery cell. The driving circuit is also electrically connected to the control terminal of the switching circuit, and the driving circuit is configured to generate a control signal in response to the result that the detected voltage is greater than the voltage threshold. The switching circuit is also connected to the control terminal of the fuse and ground, and the fuse is electrically connected between adjacent battery modules; The switching circuit is used to respond to the input of the control signal, connect the control terminal of the fuse to ground, so that the fuse blows and disconnects the electrical connection between the adjacent battery modules.

2. The thermal management circuit according to claim 1, characterized in that, The driving circuit includes a first voltage regulator unit and a signal generation unit; The first voltage regulator unit is electrically connected to the control terminal of the first node and the signal generation unit, respectively; the signal generation unit is electrically connected to the control terminal of the second power supply and the switching circuit, respectively. The first voltage regulator unit is configured to generate a first voltage regulator signal in response to the result that the detected voltage is greater than the voltage threshold, so as to control the signal generation unit to generate the control signal based on the second power supply.

3. The thermal management circuit according to claim 2, characterized in that, The signal generation unit includes a first switching unit, a first voltage divider unit, a second switching unit, and a second voltage divider unit; The control terminal of the first switching unit is electrically connected to the first voltage regulator unit. The first switching unit is connected to the first voltage divider unit and ground. The first voltage divider unit is also electrically connected to the second power supply and the control terminal of the second switching unit. The second switching unit is also electrically connected to the second power supply and the second voltage divider unit. The second voltage divider unit is also electrically connected to the switching circuit. The first switching unit is configured to respond to the input of the first regulated signal by connecting the electrical connection between the first voltage divider unit and ground, so that the first voltage divider unit divides the second power supply to generate the first voltage divider signal; The second switching unit is configured to respond to the input of the first voltage divider signal by connecting the electrical connection between the second power supply and the second voltage divider unit, so that the second voltage divider unit divides the second power supply to generate the control signal.

4. The thermal management circuit according to claim 3, characterized in that, The first voltage regulator unit includes a first Zener diode; the first switching unit includes a first resistor, a second resistor, and a first transistor; the first voltage divider unit includes a third resistor and a fourth resistor; the second switching unit includes a second transistor; and the second voltage divider unit includes a fifth resistor and a sixth resistor. The cathode of the first Zener diode is electrically connected to the first node, the anode of the first Zener diode is electrically connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor and the base of the first transistor, the other end of the second resistor and the emitter of the first transistor are grounded together, the collector of the first transistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the fourth resistor and the base of the second transistor, the other end of the fourth resistor and the emitter of the second transistor are both used to connect to the second power supply, the collector of the second transistor is connected to one end of the fifth resistor, the other end of the fifth resistor is electrically connected to one end of the sixth resistor and the control terminal of the switching circuit.

5. The thermal management circuit according to claim 2, characterized in that, The driving circuit further includes N unidirectional conduction circuits, each of which is electrically connected between the second terminal of the corresponding detection circuit and the first node. The unidirectional conduction circuit is configured to prevent reverse current from flowing into the detection circuit.

6. The thermal management circuit according to claim 2, characterized in that, The driving circuit also includes a power conversion unit, which is electrically connected to the third power supply and the signal generation unit respectively. The power conversion unit is configured to perform voltage conversion on the third power supply to obtain the second power supply.

7. The thermal management circuit according to claim 6, characterized in that, The power conversion unit includes a second voltage regulator unit and a third switching unit; The second voltage regulator unit is electrically connected to the control terminals of the third power supply and the third switching unit, respectively. The second voltage regulator unit is configured to generate a second voltage regulator signal in response to the input of the third power supply. The first end of the third switching unit is electrically connected to the third power supply, and the second end of the third switching unit is electrically connected to the signal generation unit at the second node. The third switching unit is configured to generate the second power supply in response to the input of the second regulated signal and the third power supply.

8. The thermal management circuit according to claim 7, characterized in that, The power conversion unit also includes a third voltage regulation unit and a filtering unit; The third voltage regulator unit and the filter unit are both electrically connected to the second node. The third voltage regulator unit is configured to regulate the voltage of the second power supply, and the filter unit is configured to filter the second power supply.

9. The thermal management circuit according to any one of claims 1-8, characterized in that, The detection circuit includes a heat-conducting component, a thermistor, and a voltage divider resistor. The two ends of the heat-conducting component are respectively attached to the end face of the battery cell and the thermistor to conduct the heat of the battery cell from one end of the heat-conducting component to the thermistor connected to the other end. One end of the thermistor is also electrically connected to the first power supply. The other end of the thermistor is connected to one end of the voltage divider resistor and the first node. The other end of the voltage divider resistor is grounded.

10. A battery pack, characterized in that, The battery pack includes a battery module and a thermal management circuit as described in any one of claims 1-9, wherein the battery module includes cells connected in series and / or in parallel.

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