Liquid leakage detection device for liquid-cooled lithium battery pack

Abstract

The utility model 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 utility model is suitable for the liquid-cooled lithium battery pack.

Description

TECHNICAL FIELD

[0001] The utility model belongs to electrochemical energy storage technical field, concretely relates to a liquid cooling lithium battery pack leakage detection device. BACKGROUND

[0002] In recent years, achieving the "double carbon" goal is the core task in the energy field, and building a new power system centered on clean energy such as wind and solar energy has become the key development direction of the energy and power industry. Due to the instability and volatility of wind and solar power generation, large-scale grid-connected new energy makes the power system face greater challenges in power and electricity balance. As a key flexible adjustment resource, power storage technology can realize peak-valley regulation, capacity supplement, frequency regulation and backup of power, and delay investment in power transmission networks, and is regarded as an indispensable part of the construction of new power system.

[0003] Lithium ion batteries have been widely used in the field of power storage due to their high energy density, long cycle life and low self-discharge rate. However, during charging and discharging, the battery will generate heat, and temperature has a significant impact on the capacity and life of the battery. Low temperature environment may cause battery performance to decline, while high temperature may cause thermal runaway, increasing safety risks. Therefore, in order to maintain the battery at an appropriate working temperature, the battery thermal management system becomes crucial. Currently, battery thermal management systems mainly use 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, coolant leakage or condensation occurs, and is not timely discovered and corresponding maintenance measures are not taken, the insulation isolation measures of the system will be damaged, causing insulation failure, further causing serious safety accidents and economic property losses. Therefore, leakage detection is needed.

[0005] Currently, the leakage detection schemes applied to liquid-cooled lithium battery packs include pressure sensor and flow meter detection, humidity sensor detection, and insulation detection, all of which have corresponding defects:

[0006] (1) The pressure sensor and flow meter cannot accurately locate the specific position of the leakage, and the entire battery pack is considered as a single detection unit. Only when the amount of leakage accumulates to a certain extent, causing a significant change in the flow meter reading, can it be detected, resulting in a long detection time, which may affect the thermal management efficiency of the battery pack, and even in extreme cases, it may cause battery overheating and performance degradation.

[0007] (2) The humidity sensor is not timely and accurate for detecting the leakage of the cooling liquid in the large battery energy storage container. When there is only a slight leakage of the cooling liquid in a certain space area, the humidity sensor may have difficulty in discovering the leakage in the area it is responsible for in time. Moreover, when the space area it is responsible for has a large number of battery groups, it is difficult to accurately detect the specific leakage point.

[0008] (3) The insulation detection is a leakage detection method with high accuracy, but when the leakage rate is slow, the change of the insulation resistance may not occur immediately, resulting in a delay in detection, and there are challenges in the environment 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 delay in detection. Practical new type content

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

[0011] The technical solution adopted by the present application to solve the above technical problem is:

[0012] A liquid-cooled lithium battery pack leakage detection device, comprising: 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 water-absorbing foam; the leakage detection belt is arranged at the bottom position in the battery pack and is electrically connected with 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 (battery management system) for analysis to determine whether leakage occurs.

[0013] Further, the leakage detection plate communicates with the BMS through a communication line, or is directly integrated in the BMS.

[0014] Further, the leakage detection plate comprises a signal acquisition and amplification unit, an isolation power supply circuit, a voltage stabilizing circuit, a leakage detection belt connection socket, and a BMS connection socket.

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

[0016] The isolation 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 isolation amplification circuit in the signal acquisition and amplification unit.

[0017] The voltage stabilizing circuit is used for providing 3.3V voltage to the isolated amplifier circuit and the operational amplifier circuit in the signal acquisition and amplification unit after reducing the input power provided by the BMS.

[0018] The leakage detection belt connecting socket is used for providing connection of the leakage detection belt.

[0019] The BMS connecting socket is used for providing input power to the leakage detection board by the BMS and transmitting the collected voltage signal of the leakage detection belt to the BMS.

[0020] Further, the signal acquisition and amplification unit comprises an analog acquisition circuit, an isolated amplifier circuit and an operational amplifier circuit.

[0021] The analog acquisition circuit comprises first to third resistors and first to third capacitors; the isolated amplifier circuit comprises an isolated amplifier, fifth to seventh capacitors and fourth to seventh resistors; and the operational amplifier circuit comprises 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 constitute a voltage dividing circuit and are connected between 5V voltage and an analog ground, and a voltage dividing point between the second resistor and the third resistor is connected to an IIN pin of the isolated 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 isolated amplifier and the analog ground; a VDD1 pin of the isolated amplifier is connected to the 5V voltage, and a SHUTDN pin is connected to the analog ground.

[0023] The fifth capacitor and the sixth capacitor are connected in parallel between 3.3V voltage and a digital ground; a VDD2 pin of the isolated amplifier is connected to the 3.3V voltage, and a GND2 pin is connected to the digital ground; an OUTP pin of the isolated amplifier is connected to a non-inverting input end of the first operational amplifier through a fourth resistor and a sixth resistor; an OUTN pin of the isolated amplifier is connected to an inverting input end of the first operational amplifier through a fifth resistor and a 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 noninverting input end 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 end 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 end of the first operational amplifier is connected to the digital ground, and the output end is connected to the noninverting input end of the second operational amplifier through a tenth resistor; the inverting input end of the second operational amplifier is connected to the output end thereof; the output end of the second operational amplifier is connected to the signal output of the signal acquisition and amplification unit through an eleventh resistor; and the fourteenth capacitor is connected between the signal output of the signal acquisition and amplification unit and the digital ground.

[0025] Further, the isolation power supply circuit comprises a push-pull chip, a transformer, a linear voltage stabilizing 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 stabilizing chip, the tap of the secondary coil of the transformer is connected to the GND pin of the linear voltage stabilizing chip, and the ninth capacitor and the tenth capacitor are connected in parallel between the Vin pin and the GND pin of the linear voltage stabilizing chip; the Vout pin of the linear voltage stabilizing chip outputs a 5V voltage, and is connected to the GND pin through the thirteenth capacitor.

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

[0027] The VIN pin of the LDO voltage stabilizing chip is connected to the input power supply and is 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; and the GND pin of the LDO voltage stabilizing chip is connected to the digital ground.

[0028] Further, the leakage detection belt is connected to the 1 pin and the 2 pin of the socket, the positive electrode of the leakage detection belt is provided, the 3 pin and the 4 pin are connected, and the negative electrode of the leakage detection belt is provided.

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

[0030] The utility model discloses the beneficial effect is:

[0031] Based on the structural design of the above-mentioned liquid leakage detection device, the liquid leakage detection belt has high sensitivity. Once liquid leakage occurs, the water-absorbing foam in the detection belt will instantly absorb the liquid to cause conduction between the two wires, thereby causing a change in the voltage on the liquid leakage detection belt. The signal is collected by the liquid leakage detection plate and uploaded to the BMS for analysis and processing. Therefore, the scheme can timely discover and handle leakage accidents, improve the safety of the battery pack operating environment, effectively prevent insulation failure, short circuit and other adverse reactions caused by liquid leakage, reduce the downtime of the production line caused by leakage, reduce maintenance costs, improve production efficiency, and save a lot of cost expenditure for enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structure schematic view of the liquid leakage detection plate in the embodiment;

[0033] Figure 2 It is a resistance change curve diagram of the liquid leakage detection belt when different types of liquid leakage occur

[0034] The figure mark explanation: a is a signal collection and amplification unit, b is an isolation power supply circuit, c is a voltage stabilizing circuit, d is a liquid leakage detection belt connection socket, e is a BMS connection socket, R1-R11 are first to eleventh resistors, C1-C17 are first to seventeenth capacitors, D1 is a first diode, D2 is a 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 liquid leakage detection belt connection socket, J1 is a BMS connection socket, LIQ_POWER is an input power supply, LIQ_DEC is a signal output of the signal collection and amplification unit, DVSS is a digital ground, and AGND is an analog ground. DETAILED DESCRIPTION

[0035] The utility model aims at providing a kind of liquid cooling lithium battery pack liquid leakage detection device, solve the problem of low liquid leakage detection precision, long time consumption, detection delay in the liquid leakage detection scheme of prior art of liquid cooling lithium battery pack.The core idea is: the detection device includes liquid leakage detection belt and liquid leakage detection plate;Among them, liquid leakage detection belt includes two parallel conductive cables wrapped with water-absorbing foam, liquid leakage detection belt is arranged at the bottom position in battery pack, and is electrically connected with liquid leakage detection plate, forms loop;When battery pack does not occur liquid leakage, due to the isolation of water-absorbing foam, the insulation between the two conductive cables, when liquid leakage occurs, liquid is absorbed by water-absorbing foam, causes two cable conduction, so that the voltage on the detection belt changes, the signal is collected by liquid leakage detection plate and transmitted to BMS for analysis, can be judged that liquid leakage has occurred according to voltage change.In addition, since the conductivity of different liquids is different, when liquid leakage occurs, the specific liquid leakage type can be judged according to the size of the detected voltage.

[0036] The utility model discloses a scheme further described below in connection with the drawings and examples.

[0037] Embodiment:

[0038] The liquid leakage detection device for liquid-cooled lithium battery pack provided in the embodiment comprises a liquid leakage detection belt and a liquid leakage detection plate; wherein the liquid leakage detection belt is belt-shaped, comprising two parallel conductive cables, and the conductive cables are wrapped with water-absorbing foam; the liquid leakage detection belt is arranged at the bottom position in the battery pack and is electrically connected with the liquid leakage detection plate to form a loop; the liquid leakage detection plate is used for collecting the voltage signal of the liquid leakage detection belt and transmitting the voltage signal to the BMS for analysis to determine whether liquid leakage occurs.

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

[0040] An exemplary liquid leakage detection plate circuit structure is shown in Figure 1 It comprises a signal acquisition and amplification unit a, an isolation power supply circuit b, a voltage stabilizing circuit c, a liquid leakage detection belt connection socket d and a BMS connection socket e. The specific implementation and functions of each part are specifically introduced as follows:

[0041] ① Signal acquisition and amplification unit a: a system for converting analog signals into digital signals, which functions to collect the voltage at both ends of the resistance when the liquid on the liquid leakage detection belt conducts the two parallel conductive cables. It comprises an analog acquisition circuit, an isolation amplification circuit and an operational amplification circuit.

[0042] The analog acquisition circuit comprises first to third resistors R1-R3 and first to third capacitors C1-C3; the isolation amplification circuit comprises an isolation amplifier U2, fifth to seventh capacitors C5-C7 and fourth to seventh resistors R4-R7; and the operational amplification circuit comprises 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.

[0043] The first resistor R1, the second resistor R2 and the third resistor R3 constitute a voltage division circuit, are connected between a 5V voltage and an analog ground AGND, and a voltage division 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; a VDD1 pin of the isolation amplifier U2 is connected to the 5V voltage, and a SHUTDN pin is connected to the analog ground AGND.

[0044] The fifth capacitor C5 and the sixth capacitor C6 are connected in parallel between a 3.3V voltage and a digital ground DVSS; a VDD2 pin of the isolation amplifier U2 is connected to the 3.3V voltage, and a GND2 pin is connected to the digital ground DVSS; an 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; an 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 a 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, a positive power supply terminal of the first operational amplifier is connected to the 3.3V voltage, and a twelfth capacitor C12 is connected between the 3.3V voltage and the digital ground DVSS; a negative power supply terminal of the first operational amplifier is connected to the digital ground DVSS, and an output terminal is connected to a non-inverting input terminal of the second operational amplifier through a tenth resistor R10; an inverting input terminal of the second operational amplifier is connected to the output terminal thereof; an output terminal of the second operational amplifier is connected to a signal output LIQ_DEC of a signal acquisition and amplification unit through an eleventh resistor R11; and a 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 constitute 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 its function is to convert a single-ended analog voltage signal into a differential analog output; the operational amplifier circuit includes an RC filter circuit and an amplification circuit, which functions to filter and convert the differential analog voltage signal into a single-ended voltage signal output to the BMS for voltage acquisition; 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 together 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 the current, protect the operational amplifier from damage, reduce the output offset voltage, improve the following 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] ②Isolation 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 isolation amplification circuit in the signal acquisition and amplification unit.

[0048] The isolation power supply circuit includes a push-pull chip U1, a transformer T1, a linear voltage stabilizing 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 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 with the first diode D1 and the second diode D2, and are both connected to the Vin pin of the linear voltage stabilizing chip U4, the tap of the secondary coil of the transformer T1 is connected to the GND pin of the linear voltage stabilizing chip U4, and 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 stabilizing chip U4; the Vout pin of the linear voltage stabilizing chip U4 outputs a 5V voltage, and the GND pin is connected through the thirteenth capacitor C13.

[0049] In the above isolation power supply circuit, the fourth capacitor C4 is used for filtering to reduce power supply noise; the transformer T1 is designed to use the secondary-to-primary turns ratio of the transformer to set the output voltage; the first diode D1 and the second diode D2 are rectifier diodes used to convert the alternating current output by the transformer T1 into direct current; 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; and the linear voltage regulator U4 is used to provide a stable output voltage.

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

[0051] ③ The voltage stabilizing circuit c is used to provide 3.3V voltage to the isolation amplifier circuit and the operational amplifier circuit in the signal acquisition and amplification unit after stepping down the input power provided by the BMS.

[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 LIQ_POWER and is connected to the digital ground DVSS through the fifteenth capacitor C15. The VOUT pin outputs 3.3V voltage and is connected to the digital ground DVSS through the 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 high-frequency noise of the input power to stabilize the input voltage. The sixteenth capacitor C16 is located at the output end and is used to stabilize the output voltage to reduce the fluctuation of the output voltage. The seventeenth capacitor C17 is also located at the output end and is used to filter out high-frequency noise of the output voltage to 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 noise and voltage fluctuation are reduced.

[0054] Based on the design of the above voltage stabilizing circuit, low-voltage area power supply can be provided to prevent the output of the operational amplifier from exceeding the safe working voltage of the low-voltage area circuit, damaging the BMS sampling port, and improving the reliability of the BMS system.

[0055] ④ The leakage detection tape connection socket d is used to provide connection for the leakage detection tape.

[0056] The 1-pin and the 2-pin of the leakage detection belt connecting socket are connected to provide the positive electrode access of the leakage detection belt, and the 3-pin and the 4-pin are connected to provide the negative electrode access of the leakage detection belt.

[0057] 5. The BMS connecting 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.

[0058] The 1-pin of the BMS connecting socket is connected to the signal output of the signal collection and amplification unit; the 2-pin is connected to the digital ground, and the 3-pin 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 by the embodiment is as follows: when no leakage occurs, the two conductive cables in the leakage detection belt are insulated from each other through the water-absorbing foam, that is, the resistance is infinite. When leakage occurs, the liquid is absorbed by the water-absorbing foam, so that the liquid acts as a conductive medium, forming a conductive path between the two originally insulated conductive cables on the leakage detection belt to obtain an initial resistance value, which increases with time. According to Ohm's law, the partial voltage of the leakage detection belt also increases, and this information is collected by the leakage detection board and transmitted to the BMS, so that it can be judged that the current leakage has occurred.

[0060] In addition, there are usually three kinds of battery pack leakage: electrolyte leakage of the battery cell, cooling liquid leakage of the liquid cooling pipe, and condensation liquid leakage in the battery pack; and the conductivities of the three kinds of liquid are different, so the resistance values of the leakage detection belt paths are also different, as shown in Figure 2 Therefore, the voltage signal collected by the leakage detection board is also different, and accordingly, the BMS can accurately judge the type of leakage, and the judgment result can be transmitted to the outside to take corresponding maintenance measures in time.

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

[0062] Although the embodiments of the utility model have been described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the utility model, and all of them do not depart from the protection scope of the utility model.

Claims

1. A liquid leakage detection device for a liquid-cooled lithium battery pack, characterized by, The liquid cooling lithium battery pack leak detection device comprises a leak detection belt and a leak detection plate; the leak detection belt comprises two parallel conductive cables, and the conductive cables are wrapped with water absorption foam; The leak detection belt is arranged at a bottom position in the battery pack and is electrically connected with the leak detection plate to form a loop; the leak detection plate is used for collecting a voltage signal of the leak detection belt and transmitting the voltage signal to the BMS for analysis to determine whether liquid leakage occurs.

2. The liquid cooling lithium battery pack leak detection device according to claim 1, wherein the leak detection plate communicates with the BMS through a communication line or is directly integrated in the BMS.

3. The liquid cooling lithium battery pack leak detection device according to claim 1, wherein the leak detection plate comprises a signal collection and amplification unit (a), an isolated power supply circuit (b), a voltage stabilizing circuit (c), a leak detection belt connecting socket (d) and a BMS connecting socket (e); the signal collection and amplification unit (a) is used for collecting a voltage signal of the leak detection belt; the isolated power supply circuit (b) is used for converting an input power provided by the BMS into an isolated 5V voltage to supply power to an analog collection circuit and an isolated amplification circuit in the signal collection and amplification unit; the voltage stabilizing circuit (c) is used for obtaining a 3.3V voltage by step-down of the input power provided by the BMS to supply power to the isolated amplification circuit and an operational amplification circuit in the signal collection and amplification unit; the leak detection belt connecting socket (d) is used for providing connection of the leak detection belt; the BMS connecting socket (e) is used for providing the input power to the leak detection plate through the BMS and transmitting the collected voltage signal of the leak detection belt to the BMS.

4. The liquid cooling lithium battery pack leak detection device according to claim 3, wherein the signal collection and amplification unit (a) comprises an analog collection circuit, an isolated amplification circuit and an operational amplification circuit; the analog collection circuit comprises first to third resistors (R1-R3) and first to third capacitors (C1-C3); the isolated amplification circuit comprises an isolated amplifier (U2), fifth to seventh capacitors (C5-C7) and fourth to seventh resistors (R4-R7); and the operational amplification circuit comprises 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); first to third resistors (R1-R3) constitute a voltage dividing circuit and are connected between a 5V voltage and an analog ground (AGND), a voltage dividing point between the second resistor (R2) and the third resistor (R3) is connected to an IIN pin of the isolated amplifier (U2), and 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 isolated amplifier (U2) and the analog ground (AGND); a VDD1 pin of the isolated amplifier (U2) is connected to the 5V voltage, and a SHUTDN pin is connected to the analog ground (AGND). ​ ​ ​ ​ 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); The non-inverting input terminal of the first operational amplifier is connected to the digital ground (DVSS) through the parallel circuit of the eighth resistor (R8) and the eighth capacitor (C8), the positive power supply terminal of the first operational amplifier is connected to the 3.3V voltage, and the 3.3V voltage and the digital ground (DVSS) are connected through the twelfth capacitor (C12); 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 the 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 the 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. The liquid-cooled lithium battery leakage detection device of claim 4, wherein The isolation power supply circuit (b) comprises a push-pull chip (U1), a transformer (T1), a linear voltage stabilizing 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 (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 stabilizing chip (U4); the tap of the secondary coil of the transformer (T1) is connected to the GND pin of the linear voltage stabilizing 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 stabilizing chip (U4); the Vout pin of the linear voltage stabilizing chip (U4) outputs a 5V voltage, and is connected to the GND pin through the thirteenth capacitor (C13).

6. The liquid-cooled lithium battery leakage detection device of claim 5, wherein 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); the VIN pin of the LDO voltage stabilizing chip (U3) is connected with an input power (LIQ_POWER) and is connected with a digital ground (DVSS) through the fifteenth capacitor (C15); the VOUT pin outputs a 3.3V voltage and is connected with 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 with the digital ground (DVSS).

7. The liquid leakage detection device of the liquid-cooled lithium battery pack according to claim 6, wherein the leakage detection belt is connected to the first pin and the second pin of the socket (d) to provide a positive electrode access of the leakage detection belt, and the third pin and the fourth pin are connected to provide a negative electrode access of the leakage detection belt.

8. The liquid leakage detection device of the liquid-cooled lithium battery pack according to claim 7, wherein the first pin of the BMS socket (e) is connected to a signal output of a signal acquisition and amplification unit, the second pin is connected to a digital ground, and the third pin provides an input power (LIQ_POWER) to the leakage detection board through the BMS. ​ ​

Images