Liquid leakage detection device for liquid-cooled lithium battery pack

Abstract

The invention belongs to the technical field of electrochemical energy storage, discloses a liquid leakage detection device for a liquid-cooled lithium battery pack, and solves the problems of low liquid leakage detection precision, long time consumption and detection delay in a liquid leakage detection scheme of the liquid-cooled lithium battery pack in the prior art. The device comprises a liquid leakage detection belt and a liquid leakage detection plate, the liquid leakage detection belt comprises two parallel conductive cables, and the conductive cables are wrapped by water absorption foam. The liquid leakage detection belt is arranged at the bottom in the battery pack and is electrically connected with the liquid leakage detection plate to form a loop; and the liquid leakage detection plate is used for collecting a voltage signal of the liquid leakage detection belt and transmitting the voltage signal to the BMS for analysis so as to judge whether liquid leakage occurs or not. The invention is suitable for the liquid-cooled lithium battery pack.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical energy storage, and in particular relates to a liquid-cooled lithium battery pack leakage detection device. Background Art

[0002] In recent years, achieving the "dual carbon" goal has become a core task in the energy sector, and building a new power system with clean energy such as wind and solar energy as the core has become a key development direction for the energy and power industry. Given the instability and volatility of wind and solar power generation, the large-scale grid connection of these new energy sources has made the power system face greater challenges in terms of power and electricity balance. As a key flexible regulation resource, power storage technology can achieve peak and valley regulation of electricity, capacity replenishment, frequency regulation and backup, and postpone investment in transmission networks, and is regarded as an indispensable component in the construction of a new power system.

[0003] Lithium-ion batteries have been widely used in the field of power energy storage due to their advantages such as high energy density, long cycle life and low self-discharge rate. However, during the charging and discharging process, the battery generates heat, and the temperature has a significant impact on the capacity and life of the battery. Low temperature environment may cause battery performance to deteriorate, while high temperature may cause thermal runaway and increase safety risks. Therefore, in order to maintain the battery at a suitable operating temperature, the battery thermal management system becomes crucial. At present, the battery thermal management system mainly adopts three cooling methods: air cooling, liquid cooling and phase change material cooling. Among them, liquid cooling can provide better cooling effect than air cooling under the same flow conditions due to its high heat transfer efficiency and uniform temperature distribution.

[0004] For liquid-cooled lithium battery packs, if electrolyte or coolant leaks or condensation accumulates, and it is not discovered in time and corresponding maintenance measures are not taken, the system's insulation isolation measures will be destroyed, causing insulation failure, further causing serious safety accidents and economic property losses. Therefore, leakage detection is necessary.

[0005] At present, the leakage detection schemes used in liquid-cooled lithium battery packs include pressure sensor and flow meter detection, humidity sensor detection, and insulation detection methods, all of which have corresponding defects:

[0006] (1) The pressure sensor and flow meter cannot accurately locate the specific location where the leakage occurs. The entire battery pack is regarded as a single detection unit. It can only be detected when the leakage accumulates to a certain level, causing a significant change in the flow meter reading. This causes the detection to take a long time, which may affect the thermal management efficiency of the battery pack and even in extreme cases, may cause battery overheating and performance degradation.

[0007] (2) Humidity sensors are not timely and accurate enough in detecting coolant leaks in large battery energy storage containers. When only a slight coolant leak occurs in a certain area, the humidity sensor may not be able to detect the leak in the area it is responsible for in time. Moreover, when there are many battery packs in the space area it is responsible for monitoring, it is difficult to accurately detect the specific leakage point.

[0008] (3) Insulation testing is a highly accurate means of leak detection. However, when the leakage rate is slow, the change in insulation resistance may not occur immediately, resulting in delayed detection. There are also challenges in terms of environmental impact and cost.

[0009] Therefore, in the prior art, the leakage detection scheme for the liquid-cooled lithium battery pack has the problems of low leakage detection accuracy, long time consumption, and detection delay. Summary of the invention

[0010] The technical problem to be solved by the present invention is to propose a liquid-cooled lithium battery pack leakage detection device to solve the problems of low leakage detection accuracy, long time consumption and detection delay in the leakage detection scheme of the liquid-cooled lithium battery pack in the prior art.

[0011] The technical solution adopted by the present invention to solve the above technical problems is:

[0012] A liquid-cooled lithium battery pack leakage detection device comprises: a leakage detection belt and a leakage detection plate; the leakage detection belt comprises two parallel conductive cables, and the conductive cables are wrapped with absorbent foam; the leakage detection belt is arranged at the bottom position in the battery pack and is electrically connected to the leakage detection plate to form a loop; the leakage detection plate is used to collect a voltage signal of the leakage detection belt, and transmit the voltage signal to a BMS (battery management system) for analysis to determine whether leakage occurs.

[0013] Furthermore, the leakage detection board communicates with the BMS via a communication line, or is directly integrated into the BMS.

[0014] Furthermore, the leakage detection board includes a signal acquisition and amplification unit, an isolation power supply circuit, a voltage stabilization circuit, a leakage detection belt connection socket and a BMS connection socket;

[0015] The signal acquisition and amplification unit is used to acquire the voltage signal of the leakage detection belt;

[0016] The isolated power supply circuit is used to convert the input power provided by the BMS into an isolated 5V voltage to power the analog acquisition circuit and the isolated amplifier circuit in the signal acquisition and amplification unit;

[0017] The voltage stabilizing circuit is used to reduce the voltage of the input power provided by the BMS to obtain a 3.3V voltage to power the isolation amplifier circuit and the operational amplifier circuit in the signal acquisition and amplification unit;

[0018] The liquid leakage detection belt connection socket is used to provide connection for the liquid leakage detection belt;

[0019] The BMS connection socket is used to provide input power to the leakage detection board through the BMS and transmit the collected voltage signal of the leakage detection belt to the BMS.

[0020] Furthermore, the signal acquisition and amplification unit includes an analog acquisition circuit, an isolation amplification circuit and an operational amplification circuit;

[0021] The analog acquisition circuit includes: first to third resistors and first to third capacitors; the isolation amplifier circuit includes: an isolation amplifier, fifth to seventh capacitors and fourth to seventh resistors; the operational amplifier circuit includes: an eighth capacitor, an eleventh capacitor, a twelfth capacitor, a fourteenth capacitor, a first operational amplifier, a second operational amplifier and eighth to eleventh resistors;

[0022] The first resistor, the second resistor and the third resistor form a voltage divider circuit, which is connected between the 5V voltage and the analog ground, and the voltage divider point between the second resistor and the third resistor is connected to the IIN pin of the isolation amplifier, the first capacitor and the second capacitor are connected in parallel between the 5V voltage and the analog ground; the third capacitor is connected between the IIN pin of the isolation amplifier and the analog ground; the VDD1 pin of the isolation amplifier is connected to the 5V voltage, and the SHUTDN pin is connected to the analog ground;

[0023] The fifth capacitor and the sixth capacitor are connected in parallel between the 3.3V voltage and the digital ground; the VDD2 pin of the isolation amplifier is connected to the 3.3V voltage, and the GND2 pin is connected to the digital ground; the OUTP pin of the isolation amplifier is connected to the non-inverting input terminal of the first operational amplifier through the fourth resistor and the sixth resistor; the OUTN pin of the isolation amplifier is connected to the inverting input terminal of the first operational amplifier through the fifth resistor and the seventh resistor; one end of the seventh capacitor is connected between the fourth resistor and the sixth resistor, and the other end is connected between the fifth resistor and the seventh resistor;

[0024] The non-inverting input terminal of the first operational amplifier is connected to the digital ground through a parallel circuit of an eighth resistor and an eighth capacitor, the positive power supply terminal of the first operational amplifier is connected to a 3.3V voltage, and a twelfth capacitor is connected between the 3.3V voltage and the digital ground; the negative power supply terminal of the first operational amplifier is connected to the digital ground, and the output terminal is connected to the non-inverting input terminal of the second operational amplifier through a tenth resistor; the inverting input terminal of the second operational amplifier is connected to its output terminal; the output terminal of the second operational amplifier is connected to the signal output of the signal acquisition and amplification unit through an eleventh resistor; the fourteenth capacitor is connected between the signal output of the signal acquisition and amplification unit and the digital ground.

[0025] Furthermore, the isolation power supply circuit includes a push-pull chip, a transformer, a linear voltage regulator chip, a fourth capacitor, a ninth capacitor, a tenth capacitor, a thirteenth capacitor, a first diode and a second diode; the GND pin of the push-pull chip is connected to the digital ground, the D2 pin and the D1 pin are connected to the two ends of the primary coil of the transformer, the VCC pin is connected to the primary coil tap of the transformer and the input power supply, and is connected to the digital ground through the fourth capacitor; the two ends of the secondary coil of the transformer are respectively connected to the first diode and the second diode, and are both connected to the Vin pin of the linear voltage regulator chip, the tap of the secondary coil of the transformer is connected to the GND pin of the linear voltage regulator chip, the ninth capacitor and the tenth capacitor are connected in parallel between the Vin pin and the GND pin of the linear voltage regulator chip; the Vout pin of the linear voltage regulator chip outputs a 5V voltage and is connected to the GND pin through the thirteenth capacitor.

[0026] Further, the voltage stabilizing circuit includes an LDO voltage stabilizing chip, a fifteenth capacitor, a sixteenth capacitor and a seventeenth capacitor;

[0027] The VIN pin of the LDO voltage regulator chip is connected to the input power supply and connected to the digital ground through the fifteenth capacitor; the VOUT pin outputs a 3.3V voltage and is connected to the digital ground through a parallel circuit of the sixteenth capacitor and the seventeenth capacitor; the GND pin of the LDO voltage regulator chip is connected to the digital ground.

[0028] Furthermore, pins 1 and 2 of the liquid leakage detection belt connection socket are connected to provide positive access to the liquid leakage detection belt, and pins 3 and 4 are connected to provide negative access to the liquid leakage detection belt.

[0029] Furthermore, pin 1 of the BMS connection socket is connected to the signal output of the signal acquisition and amplification unit; pin 2 is connected to the digital ground, and pin 3 provides input power to the leakage detection board through the BMS.

[0030] The beneficial effects of the present invention are:

[0031] Based on the structural design of the above-mentioned leakage detection device, the leakage detection belt used has high sensitivity. Once leakage occurs, the absorbent foam in the detection belt will instantly absorb the liquid and cause the two wires to be connected, thereby causing the voltage on the leakage detection belt to change. The signal is collected by the leakage detection board and uploaded to the BMS for analysis and processing. Therefore, this solution can detect and handle leakage accidents in a timely manner, improve the safety of the battery pack operating environment, and effectively prevent adverse reactions such as insulation failure and short circuit caused by liquid leakage; reduce production line downtime caused by leakage, reduce maintenance costs, improve production efficiency, and save a lot of cost expenditures for enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of the liquid leakage detection board in the embodiment;

[0033] Figure 2 The resistance change curve of the leakage detection belt when different types of leakage occur

[0034] Explanation of the accompanying drawings: a is a signal acquisition and amplification unit, b is an isolation power supply circuit, c is a voltage stabilizing circuit, d is a leakage detection belt connection socket, e is a BMS connection socket, R1~R11 are the first to eleventh resistors, C1~C17 are the first to seventeenth capacitors, D1 is the first diode, D2 is the second diode, U1 is a push-pull chip, T1 is a transformer, U2 is an isolation amplifier, U3 is an LDO voltage stabilizing chip, U4 is a linear voltage stabilizing chip, E1 is a leakage detection belt connection socket, J1 is a BMS connection socket, LIQ_POWER is the input power supply, LIQ_DEC is the signal output of the signal acquisition and amplification unit, DVSS is the digital ground, and AGND is the analog ground. DETAILED DESCRIPTION

[0035] The present invention aims to provide a liquid-cooled lithium battery pack leakage detection device to solve the problems of low leakage detection accuracy, long time consumption and detection delay in the leakage detection scheme of the liquid-cooled lithium battery pack in the prior art. The core idea is that the detection device includes a leakage detection belt and a leakage detection plate; wherein the leakage detection belt includes two parallel conductive cables wrapped with absorbent foam, the leakage detection belt is arranged at the bottom of the battery pack, and is electrically connected to the leakage detection plate to form a loop; when the battery pack does not leak, the two conductive cables are insulated due to the isolation of the absorbent foam, and when leakage occurs, the liquid is absorbed by the absorbent foam, causing the two cables to be conductive, so that the voltage on the detection belt changes, and the signal is collected by the leakage detection board and transmitted to the BMS for analysis, and leakage can be judged based on the voltage change. In addition, since the conductivity of different liquids is different, when leakage occurs, the specific leakage type can be judged based on the size of the detected voltage.

[0036] The scheme of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] Example

[0038] The liquid-cooled lithium battery pack leakage detection device provided in this embodiment includes: a leakage detection belt and a leakage detection plate; wherein the leakage detection belt is in the shape of a belt, and includes two parallel conductive cables, and the conductive cables are wrapped with absorbent foam; the leakage detection belt is arranged at the bottom position in the battery pack, and is electrically connected to the leakage detection plate to form a loop; the leakage detection plate is used to collect the voltage signal of the leakage detection belt, and transmit the voltage signal to the BMS for analysis to determine whether leakage occurs.

[0039] In specific implementation, the leakage detection belt can be set to fit the bottom of the lower box of the battery pack and cover each leakage point of the battery pack, so that the leakage detection belt can sensitively capture the liquid near each leakage point. The leakage detection board can communicate with the BMS through a communication line, or be directly integrated into the BMS.

[0040] An exemplary circuit structure of a leakage detection board is as follows: Figure 1 As shown, it includes signal acquisition and amplification unit a, isolation power supply circuit b, voltage stabilization circuit c, leakage detection belt connection socket d and BMS connection socket e. The following is a detailed introduction to the specific implementation and function of each part:

[0041] ① Signal acquisition and amplification unit a: It is a system for converting analog signals into digital signals. Its function is to collect the voltage across the resistor when the liquid on the leakage detection belt conducts two parallel conductive cables. It includes several sub-circuits: analog acquisition circuit, isolation amplifier circuit and operational amplifier circuit.

[0042] The analog acquisition circuit includes: first to third resistors R1~R3 ​​and first to third capacitors C1~C3; the isolation amplifier circuit includes: isolation amplifier U2, fifth to seventh capacitors C5~C7 and fourth to seventh resistors R4~R7; the operational amplifier circuit includes: eighth capacitor C8, eleventh capacitor C11, twelfth capacitor C12, fourteenth capacitor C14, first operational amplifier, second operational amplifier and eighth to eleventh resistors R8~R11.

[0043] The first resistor R1, the second resistor R2 and the third resistor R3 form a voltage divider circuit, which is connected between the 5V voltage and the analog ground AGND, and the voltage dividing point between the second resistor R2 and the third resistor R3 is connected to the IIN pin of the isolation amplifier U2, the first capacitor C1 and the second capacitor C2 are connected in parallel between the 5V voltage and the analog ground AGND; the third capacitor C3 is connected between the IIN pin of the isolation amplifier U2 and the analog ground AGND; the VDD1 pin of the isolation amplifier U2 is connected to the 5V voltage, and the SHUTDN pin is connected to the analog ground AGND.

[0044] The fifth capacitor C5 and the sixth capacitor C6 are connected in parallel between the 3.3V voltage and the digital ground DVSS; the VDD2 pin of the isolation amplifier U2 is connected to the 3.3V voltage, and the GND2 pin is connected to the digital ground DVSS; the OUTP pin of the isolation amplifier U2 is connected to the non-inverting input terminal of the first operational amplifier through the fourth resistor R4 and the sixth resistor R6; the OUTN pin of the isolation amplifier U2 is connected to the inverting input terminal of the first operational amplifier through the fifth resistor R5 and the seventh resistor R7; one end of the seventh capacitor C7 is connected between the fourth resistor R4 and the sixth resistor R6, and the other end is connected between the fifth resistor R5 and the seventh resistor R7.

[0045] The non-inverting input terminal of the first operational amplifier is connected to the digital ground DVSS through a parallel circuit of an eighth resistor R8 and an eighth capacitor C8, the positive power supply terminal of the first operational amplifier is connected to a 3.3V voltage, and a twelfth capacitor C12 is connected between the 3.3V voltage and the digital ground DVSS; the negative power supply terminal of the first operational amplifier is connected to the digital ground DVSS, and the output terminal is connected to the non-inverting input terminal of the second operational amplifier through a tenth resistor R10; the inverting input terminal of the second operational amplifier is connected to its output terminal; the output terminal of the second operational amplifier is connected to the signal output LIQ_DEC of the signal acquisition and amplification unit through an eleventh resistor R11; the fourteenth capacitor C14 is connected between the signal output LIQ_DEC of the signal acquisition and amplification unit and the digital ground DVSS.

[0046] In the above signal acquisition and amplification unit, the first resistor R1, the second resistor R2, and the third resistor R3 form a voltage divider for adjusting the input signal (LIO+ and LIO-) to a level suitable for subsequent amplifier processing; the first capacitor C1, the second capacitor C2, and the third capacitor C3 are used for filtering to remove high-frequency noise in the input signal; the isolation amplifier U2 is a special amplifier that provides electrical isolation between the input and output circuits and converts the single-ended analog voltage signal into a differential analog output; the operational amplifier circuit includes an RC filtering circuit and an amplifying circuit, which filters the differential analog voltage signal and converts it into a single-ended voltage signal for output to BMS performs voltage collection; the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 jointly set the gain and bias of the operational amplifier; the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 are used to stabilize the operation of the operational amplifier and prevent high-frequency oscillation; the tenth resistor R10 and the eleventh resistor R11 are used to limit current, protect the operational amplifier from damage, reduce output offset voltage, improve tracking accuracy, and help stabilize the working state of the circuit; the eighth capacitor C8, the eleventh capacitor C11, the twelfth capacitor C12 and the fourteenth capacitor C14 are used for filtering and stabilizing the operation of the operational amplifier.

[0047] ②Isolated power supply circuit b: It is used to convert the input power provided by the BMS into an isolated 5V voltage to power the analog acquisition circuit and the isolated amplifier circuit in the signal acquisition and amplification unit.

[0048] The isolated power supply circuit includes a push-pull chip U1, a transformer T1, a linear voltage regulator chip U4, a fourth capacitor C4, a ninth capacitor C9, a tenth capacitor C10, a thirteenth capacitor C13, a first diode D1 and a second diode D2; the GND pin of the push-pull chip U1 is connected to the digital ground DVSS, the D2 pin and the D1 pin are connected to the two ends of the primary coil of the transformer T1, the VCC pin is connected to the primary coil tap of the transformer T1 and the input power supply LIQ_POWER, and is connected to the digital ground DVSS through the fourth capacitor C4; the two ends of the secondary coil of the transformer T1 are respectively connected to the first diode D1 and the second diode D2, and are both connected to the Vin pin of the linear voltage regulator chip U4, the tap of the secondary coil of the transformer T1 is connected to the GND pin of the linear voltage regulator chip U4, the ninth capacitor C9 and the tenth capacitor C10 are connected in parallel between the Vin pin and the GND pin of the linear voltage regulator chip U4; the Vout pin of the linear voltage regulator chip U4 outputs a 5V voltage and is connected to the GND pin through the thirteenth capacitor C13.

[0049] In the above-mentioned isolated power supply circuit, the fourth capacitor C4 is used for filtering to reduce power supply noise; the transformer T1 is designed to set the output voltage by utilizing the turns ratio of the secondary side to the primary side of the transformer; the first diode D1 and the second diode D2 are rectifier diodes, which are used to convert the AC power outputted from the secondary side of the transformer T1 into DC power; the ninth capacitor C9, the tenth capacitor C10 and the thirteenth capacitor C13 are used for filtering to smooth the rectified voltage and reduce ripples; the linear regulator U4 is used to provide a stable output voltage.

[0050] Based on the design of the above-mentioned isolated power supply circuit, advanced isolation technology is adopted to ensure the electrical isolation between the analog acquisition end and the low-voltage area through isolated power supply and signal acquisition. This design not only improves the safety of the system, but also effectively prevents the impact of potential electrical faults on the BMS, thereby ensuring the stable operation of the BMS.

[0051] ③ Voltage stabilizing circuit c: used to step down the input power provided by the BMS to obtain a 3.3V voltage to power the isolation amplifier circuit and operational amplifier circuit in the signal acquisition and amplification unit.

[0052] The voltage stabilizing circuit includes an LDO voltage stabilizing chip U3, a fifteenth capacitor C15, a sixteenth capacitor C16 and a seventeenth capacitor C17; the VIN pin of the LDO voltage stabilizing chip U3 is connected to the input power supply LIQ_POWER, and is connected to the digital ground DVSS through the fifteenth capacitor C15; the VOUT pin outputs a 3.3V voltage, and is connected to the digital ground DVSS through a parallel circuit of the sixteenth capacitor C16 and the seventeenth capacitor C17; the GND pin of the LDO voltage stabilizing chip U3 is connected to the digital ground DVSS.

[0053] In the above voltage stabilizing circuit, the fifteenth capacitor C15 is located at the input end, and is used to filter out the high-frequency noise of the input power supply and stabilize the input voltage; the sixteenth capacitor C16 is located at the output end, and is used to stabilize the output voltage and reduce the fluctuation of the output voltage; the seventeenth capacitor C17 is also located at the output end, and is used to filter out the high-frequency noise of the output voltage and further improve the stability of the output voltage; that is, through the joint action of the fifteenth capacitor C15, the sixteenth capacitor C16 and the seventeenth capacitor C17, the stability of the input and output voltages is ensured, and the noise and voltage fluctuations are reduced.

[0054] Based on the design of the voltage stabilizing circuit, it can provide power supply for the low-voltage area, prevent the output of the op amp from exceeding the safe working voltage of the low-voltage area circuit, damage the BMS sampling port, and improve the reliability of the BMS system.

[0055] ④ Liquid leakage detection tape connection socket d: it is used to provide connection for the liquid leakage detection tape.

[0056] The 1st and 2nd pins of the liquid leakage detection belt connection socket are connected to provide positive access to the liquid leakage detection belt, and the 3rd and 4th pins are connected to provide negative access to the liquid leakage detection belt.

[0057] ⑤BMS connection socket e: It is used to provide input power to the leakage detection board through the BMS and transmit the collected voltage signal of the leakage detection belt to the BMS.

[0058] Pin 1 of the BMS connection socket is connected to the signal output of the signal acquisition and amplification unit; pin 2 is connected to the digital ground, and pin 3 provides input power LIQ_POWER to the leakage detection board through the BMS.

[0059] The working principle of the liquid-cooled lithium battery pack leakage detection device provided in this embodiment is: when no leakage occurs, the two conductive cables in the leakage detection belt are insulated from each other by the absorbent foam, that is, the resistance is infinite. When leakage occurs, the liquid is absorbed by the absorbent foam, so that the liquid acts as a conductive medium, and a conductive path is formed between the two originally insulated wires on the leakage detection belt to obtain an initial resistance value, which increases with time. According to Ohm's law, the partial pressure of the leakage detection belt also increases accordingly. This information is collected by the leakage detection board and transmitted to the BMS, and it can be determined that leakage has occurred.

[0060] In addition, there are usually three types of battery pack leakage: electrolyte leakage from the battery cell, coolant leakage from the liquid cooling pipeline, and condensation accumulation in the battery pack; the conductivity of these three liquids is different, so the resistance value of the leakage detection band path will also be different, see Figure 2 , then correspondingly, the voltage signal collected by the leakage detection board will also be different. Based on this, the BMS can accurately determine the type of leakage, and the judgment result can be transmitted to the outside world so that corresponding maintenance measures can be taken in time.

[0061] For the sake of low power design, the leakage detection device in this embodiment also has a low power consumption function. When the product is in sleep mode, the BMS can automatically detect and turn off the leakage detection function, thereby reducing system power consumption. This design not only improves energy utilization efficiency, but also ensures that the system can respond quickly and resume normal working state when needed, providing strong guarantee for safe transportation and storage.

[0062] Although the embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principle and spirit of the present invention, all without departing from the scope of protection of the present invention.

Claims

1. A liquid-cooled lithium battery pack leakage detection device, characterized in that: include: A liquid leakage detection belt and a liquid leakage detection plate; the liquid leakage detection belt comprises two parallel conductive cables, and the conductive cables are wrapped with absorbent foam; The leakage detection belt is arranged at the bottom of the battery pack and is electrically connected to the leakage detection board to form a loop; the leakage detection board is used to collect the voltage signal of the leakage detection belt and transmit the voltage signal to the BMS for analysis to determine whether leakage occurs.

2. A liquid-cooled lithium battery pack leakage detection device as claimed in claim 1, characterized in that: The leakage detection board communicates with the BMS via a communication line, or is directly integrated in the BMS.

3. A liquid-cooled lithium battery pack leakage detection device as claimed in claim 1, characterized in that: The leakage detection board comprises a signal acquisition and amplification unit (a), an isolation power supply circuit (b), a voltage stabilization circuit (c), a leakage detection belt connection socket (d) and a BMS connection socket (e); The signal acquisition and amplification unit (a) is used to acquire the voltage signal of the leakage detection belt; The isolated power supply circuit (b) is used to convert the input power provided by the BMS into an isolated 5V voltage to power the analog acquisition circuit and the isolated amplifier circuit in the signal acquisition and amplification unit; The voltage stabilizing circuit (c) is used to reduce the voltage of the input power provided by the BMS to obtain a 3.3V voltage to power the isolation amplifier circuit and the operational amplifier circuit in the signal acquisition and amplification unit; The liquid leakage detection belt connection socket (d) is used to provide connection for the liquid leakage detection belt; The BMS connection socket (e) is used to provide input power to the leakage detection board through the BMS and transmit the collected voltage signal of the leakage detection belt to the BMS.

4. A liquid-cooled lithium battery pack leakage detection device as claimed in claim 3, characterized in that: The signal acquisition and amplification unit (a) comprises an analog acquisition circuit, an isolation amplification circuit and an operational amplification circuit; The analog acquisition circuit includes: first to third resistors (R1-R3) and first to third capacitors (C1-C3); the isolation amplifier circuit includes: an isolation amplifier (U2), fifth to seventh capacitors (C5-C7) and fourth to seventh resistors (R4-R7); the operational amplifier circuit includes: an eighth capacitor (C8), an eleventh capacitor (C11), a twelfth capacitor (C12), a fourteenth capacitor (C14), a first operational amplifier, a second operational amplifier and eighth to eleventh resistors (R8-R11); The first resistor (R1), the second resistor (R2) and the third resistor (R3) form a voltage divider circuit, which is connected between a 5V voltage and an analog ground (AGND), and a voltage divider point between the second resistor (R2) and the third resistor (R3) is connected to an IIN pin of the isolation amplifier (U2); the first capacitor (C1) and the second capacitor (C2) are connected in parallel between the 5V voltage and the analog ground (AGND); the third capacitor (C3) is connected between the IIN pin of the isolation amplifier (U2) and the analog ground (AGND); the VDD1 pin of the isolation amplifier (U2) is connected to a 5V voltage, and the SHUTDN pin is connected to an analog ground (AGND); The fifth capacitor (C5) and the sixth capacitor (C6) are connected in parallel between a 3.3V voltage and a digital ground (DVSS); the VDD2 pin of the isolation amplifier (U2) is connected to a 3.3V voltage, and the GND2 pin is connected to a digital ground (DVSS); the OUTP pin of the isolation amplifier (U2) is connected to a non-inverting input terminal of the first operational amplifier through a fourth resistor (R4) and a sixth resistor (R6); the OUTN pin of the isolation amplifier (U2) is connected to an inverting input terminal of the first operational amplifier through a fifth resistor (R5) and a seventh resistor (R7); one end of the seventh capacitor (C7) is connected between the fourth resistor (R4) and the sixth resistor (R6), and the other end is connected between the fifth resistor (R5) and the seventh resistor (R7); The non-inverting input terminal of the first operational amplifier is connected to the digital ground (DVSS) through a parallel circuit of an eighth resistor (R8) and an eighth capacitor (C8), the positive power supply terminal of the first operational amplifier is connected to a 3.3V voltage, and a twelfth capacitor (C12) is connected between the 3.3V voltage and the digital ground (DVSS); the negative power supply terminal of the first operational amplifier is connected to the digital ground (DVSS), and the output terminal is connected to the non-inverting input terminal of the second operational amplifier through a tenth resistor (R10); the inverting input terminal of the second operational amplifier is connected to its output terminal; the output terminal of the second operational amplifier is connected to the signal output (LIQ_DEC) of the signal acquisition and amplification unit through an eleventh resistor (R11); the fourteenth capacitor (C14) is connected between the signal output (LIQ_DEC) of the signal acquisition and amplification unit and the digital ground (DVSS).

5. A liquid-cooled lithium battery pack leakage detection device as claimed in claim 4, characterized in that: The isolated power supply circuit (b) comprises a push-pull chip (U1), a transformer (T1), a linear voltage regulator chip (U4), a fourth capacitor (C4), a ninth capacitor (C9), a tenth capacitor (C10), a thirteenth capacitor (C13), a first diode (D1) and a second diode (D2); The GND pin of the push-pull chip (U1) is connected to the digital ground (DVSS), the D2 pin and the D1 pin are connected to the two ends of the primary coil of the transformer (T1), the VCC pin is connected to the primary coil tap of the transformer (T1) and the input power supply (LIQ_POWER), and is connected to the digital ground (DVSS) through the fourth capacitor (C4); the two ends of the secondary coil of the transformer (T1) are respectively connected to the first diode (D1) and the second diode (D2), and are both connected to the Vin pin of the linear voltage regulator chip (U4), the tap of the secondary coil of the transformer (T1) is connected to the GND pin of the linear voltage regulator chip (U4), the ninth capacitor (C9) and the tenth capacitor (C10) are connected in parallel between the Vin pin and the GND pin of the linear voltage regulator chip (U4); the Vout pin of the linear voltage regulator chip (U4) outputs a 5V voltage and is connected to the GND pin through the thirteenth capacitor (C13).

6. A liquid-cooled lithium battery pack leakage detection device as claimed in claim 5, characterized in that: The voltage stabilizing circuit (c) comprises an LDO voltage stabilizing chip (U3), a fifteenth capacitor (C15), a sixteenth capacitor (C16) and a seventeenth capacitor (C17); a VIN pin of the LDO voltage stabilizing chip (U3) is connected to an input power supply (LIQ_POWER) and is connected to a digital ground (DVSS) through the fifteenth capacitor (C15); a VOUT pin outputs a 3.3V voltage and is connected to a digital ground (DVSS) through a parallel circuit of a sixteenth capacitor (C16) and a seventeenth capacitor (C17); a GND pin of the LDO voltage stabilizing chip (U3) is connected to a digital ground (DVSS).

7. A liquid-cooled lithium battery pack leakage detection device as claimed in claim 6, characterized in that: Pin 1 and pin 2 of the leakage detection belt connection socket (d) are connected to provide positive access to the leakage detection belt, and pin 3 and pin 4 are connected to provide negative access to the leakage detection belt.

8. A liquid-cooled lithium battery pack leakage detection device as claimed in claim 7, characterized in that: Pin 1 of the BMS connection socket (e) is connected to the signal output of the signal acquisition and amplification unit; Pin 2 is connected to the digital ground, and Pin 3 provides input power (LIQ_POWER) to the liquid leakage detection board through the BMS.

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