A method and system for detecting the leakage safety of the top cover of a power battery pack

Abstract

The present invention provides a method and system for detecting the leakage safety of the top cover of a power battery pack, which relates to the technical field of detecting the leakage of the top cover of a battery pack. In the present invention, a top cover insulation detection circuit is formed by applying a pulse signal source and a detection resistor to the top cover of each battery in the battery pack to be detected, and the insulating materials between the top cover of the power battery and the positive and negative electrode posts are equivalent to the insulation resistors of the positive and negative electrode posts to construct an equivalent insulation circuit model, calculate the insulation resistors of the positive and negative electrode posts, establish a dust deposition model and train the model, take the environmental parameters and electrode post parameters of the battery at the current moment after being processed by the sliding window method as the input of the trained model, output the dust thickness of the positive and negative electrodes through the model, calculate the resistance value of the dust according to the real-time environmental parameters and electrode post parameters of the battery, and calculate the actual leakage amount and the real-time leakage amount according to the detected insulation resistors of the positive electrode post, the negative electrode post, the resistance value of the dust and the battery voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of leakage detection of battery pack top covers, and specifically to a method and system for safety detection of leakage of power battery pack top covers. Background Art

[0002] In the past few years, with the widespread application of power battery packs in fields such as electric vehicles and energy storage systems, the safety issues of batteries have been increasingly emphasized. In particular, the insulation performance of the battery pack top cover is crucial for preventing leakage faults in the battery pack.

[0003] However, in traditional battery pack safety detection methods, the insulation state of the battery top cover is often judged by simple voltage or current detection. This method is difficult to accurately reflect the actual insulation condition of the top cover, and generally has problems such as inaccurate detection and poor real-time performance. Especially in complex environments such as high temperature, high humidity, and dust, it is difficult to effectively evaluate the insulation resistance of the battery. As the battery usage time increases, factors such as dust and corrosion may cause the aging or thinning of the insulation layer of the battery top cover, thereby affecting the safety of the battery pack. Therefore, there is an urgent need for a detection method that can accurately detect the insulation performance of the power battery top cover and reflect the real-time and actual changes in battery leakage to improve battery safety and reduce the risk of battery failure.

[0004] The above information disclosed in the background art section is only used to enhance the understanding of the background of the present disclosure, and therefore it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for safety detection of leakage of power battery pack top covers to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A method for safety detection of leakage of power battery pack top covers, the specific steps include:

[0008] Step 1: Apply the positive end of a pulse signal source to the top cover of each battery in the battery pack to be detected. The negative end of the pulse signal source is connected to a detection resistor, and the detection resistor is respectively connected in series with a current-limiting resistor and electrically connected to the positive and negative electrode posts of the battery to form a top cover insulation detection circuit;

[0009] Step 2: Equivalent the insulating material between the power battery top cover and the positive and negative electrode posts to the insulation resistance of the positive and negative electrode posts, and construct an equivalent insulation circuit model with the top cover insulation detection circuit. Calculate the insulation resistance of the positive and negative electrode posts through the positive and negative voltages applied by the pulse signal source within the signal period and the detection voltage of the detection resistor in the detection circuit within the period, and according to Kirchhoff's law;

[0010] Step 3: Obtain the historical working environment parameters and terminal post parameters of different battery packs, stamp them with timestamps to form a time-series data set, perform time-series segmentation on the time-series data set by means of a sliding window method, establish a dust deposition model, use the segmented time-series data set at the current moment as the input of the model, and use the dust thicknesses of the positive and negative terminal posts at the next moment as the outputs of the model to train the model;

[0011] Step 4: Use the environmental parameters and terminal post parameters of the battery at the current moment after being processed by the sliding window method as the input of the trained model, output the dust thicknesses of the positive and negative terminals through the model, and calculate the resistance value of the dust according to the real-time environmental parameters and terminal post parameters of the battery and the influence of temperature and humidity on the conductivity of the dust respectively;

[0012] Step 5: Calculate the true resistance values of the insulating materials between the positive and negative terminal posts and the battery top cover according to the detected insulating resistances of the positive terminal post, the negative terminal post and the resistance value of the dust, calculate the actual leakage current and the real-time leakage current according to the true resistance value and the battery voltage, compare with the leakage current threshold to judge the leakage situation, and take measures.

[0013] Further, the top cover insulation detection circuit includes a pulse signal source U s 、a detection resistor R f 、a current-limiting resistor R 1 、a current-limiting resistor R 2 、a positive terminal post, and a negative terminal post. The pulse signal source U s includes a pulse positive output terminal and a pulse negative output terminal. The pulse positive output terminal is electrically connected to the battery top cover, the pulse negative output terminal is electrically connected to one end of the detection resistor R f , one end of the detection resistor R f is electrically connected to one ends of the current-limiting resistor R 1 and the current-limiting resistor R 2 respectively, the other end of the current-limiting resistor R 1 is electrically connected to the positive terminal post, and the other end of the current-limiting resistor R 2 is electrically connected to the negative terminal post.

[0014] Further, the equivalent insulation circuit model includes a positive terminal post insulation resistor R p 、a negative terminal post insulation resistor R n and the top cover insulation detection circuit. One end of the positive terminal post insulation resistor R p is electrically connected to the battery top cover and the negative terminal post insulation resistor R n , the other end of the positive terminal post insulation resistor R p is electrically connected to the positive terminal post, and the other end of the negative terminal post insulation resistor R n is electrically connected to the negative terminal post.

[0015] Furthermore, the specific steps for calculating the insulation resistances of the positive and negative electrode posts are as follows:

[0016] When the voltage applied by the pulse signal within the period is a positive voltage, according to Kirchhoff's law, the voltage across the detection resistor can be calculated. The calculation formula is:

[0017] I f+ = I 1+ + I 2+

[0018] I f+ = I 3+ + I 4+

[0019] U = R n * I 4+ - R P * I 3+

[0020] U = R 1 * I 1+ - R 2 * I 2+

[0021] U s+ = R p * I 3+ + R 1 * I 1+ + R f * I f+

[0022] Among them, U s+ is the positive voltage applied by the pulse signal within the period, and I 1+ , I 2+ , I 3+ , I 4+ , I f+ are respectively the currents passing through the current-limiting resistors R 1 , R 2 , the insulation resistance R p of the positive electrode post, the insulation resistance R n of the negative electrode post, and the detection resistor R f . U is the voltage across the positive and negative electrode posts of the power battery;

[0023] Since R 1 = R 2 = R, according to the above formula, the voltage across the detection resistor R f can be calculated. The calculation formula for the voltage is:

[0024]

[0025] Among them, Uf+ Detect the voltage across resistor R when a positive voltage is applied within the period of the pulse signal f across both ends;

[0026] When the voltage applied within the period of the pulse signal is a negative voltage;

[0027] The voltage across the detection resistor R can be calculated f across both ends, and the calculation formula for the voltage is:

[0028]

[0029] where, U f- is the voltage across the detection resistor R when a negative voltage is applied within the period of the pulse signal f across both ends;

[0030] The insulation resistance R of the positive terminal post p , the insulation resistance R of the negative terminal post n The calculation formula is:

[0031]

[0032] where, R p is the insulation resistance of the positive terminal post, R n is the insulation resistance of the negative terminal post.

[0033] Furthermore, the post parameters include the post material, the post area, and the post temperature;

[0034] The working environment parameters include temperature, humidity, and particulate concentration.

[0035] Furthermore, the calculation formula of the sliding window method is:

[0036]

[0037] where, X is the segmented time series data set, xn na is the nth influencing factor in the time series data set, ti is the current time, and nc is the width of the sliding window.

[0038] Furthermore, the dust deposition model is based on a long short-term memory neural network, and the long short-term memory neural network includes an input gate, a forget gate, and an output gate;

[0039] The equation expression of the forget gate is:

[0040] f t = δ(W f · [h t-1 , x t + b f )

[0041] where, ft is the current switch state of the forget gate, δ represents the sigmoid function, W f is the weight of the forget gate, b f is the bias parameter of the forget gate, h t-1 is the hidden state at the previous moment, x t is the current data input switch;

[0042] Determines how much of the cell state at the previous moment needs to be retained to the current moment;

[0043] The equation expression of the input gate is:

[0044] i t = δ(W i · [h t-1 , x t + b i )

[0045] where, i t is the current switch state of the input gate, δ represents the sigmoid function, W i is the weight of the input gate, b i is the bias parameter of the input gate, h t-1 is the output hidden state at the previous moment, x t is the time series data set segmented at the current moment;

[0046]

[0047] where, Candidate cell state, tanh represents the hyperbolic tangent function, W c is the candidate cell weight, b c is the candidate cell state bias parameter, h t-1 is the hidden state at the previous moment, x t is the current data input switch;

[0048] Determines how much of the input data of the network at the current moment needs to be saved to the cell state;

[0049] The update equation is:

[0050]

[0051] where, C t Current cell state, C t-1 is the cell state at the previous moment;

[0052] The equation expression of the output gate is:

[0053] o t = (W o · [h t-1 , xt +b o )

[0054] h t =o t *tanh(C t )

[0055] where o t is the current switch state of the output gate, δ represents the sigmoid function, W o is the weight of the output gate, b o is the bias parameter of the output gate, h t-1 is the hidden state at the previous moment, x t is the current data input switch, h t is the dust thickness of the positive and negative electrode posts at the next moment;

[0056] controls how much of the current cell state needs to be output to the current output value;

[0057] where the mathematical expressions of the sigmoid function and the hyperbolic tangent function are:

[0058]

[0059] where δ(x γ ) is the sigmoid function, x γ is the input of the sigmoid function, tanh(C t ) is the hyperbolic tangent function, C t is the input of the function.

[0060] Furthermore, the specific steps for calculating the resistance value of the dust according to the effects of temperature and humidity on the conductivity of the dust are as follows:

[0061] The effect of humidity on the conductivity of the dust, the calculation formula is:

[0062] σ s =σ 0 *(1 + k s *Sd)

[0063] where σ s is the conductivity of the dust under the influence of humidity, σ 0 is the conductivity of the dust under standard temperature and humidity, k s is the humidity influence coefficient, and Sd is the humidity of the dust;

[0064] The effect of temperature on the conductivity of the dust, the calculation formula is:

[0065]

[0066] where σw The conductivity of dust under the influence of temperature, σ 0 The conductivity of dust at standard temperature and humidity, k w The humidity influence coefficient, T h is the temperature of the dust;

[0067] The resistance value of the dust, and the calculation formula is:

[0068]

[0069] wherein, R h is the resistance value of the dust, H h is the thickness of the dust, S j is the area covered by the dust on the terminal post.

[0070] Furthermore, the calculation formula for the true resistance values of the positive and negative terminal posts is:

[0071] R zp = R p - R h

[0072] R zn = R n - R h

[0073] wherein, R zp is the true resistance value of the insulation resistance of the positive terminal post, R zn is the true resistance value of the insulation resistance of the negative terminal post, R p is the insulation resistance of the positive terminal post, R n is the insulation resistance of the negative terminal post, R h is the resistance value of the dust;

[0074] The calculation formulas for the actual leakage current and the real-time leakage current are:

[0075]

[0076] wherein, I sj is the real-time leakage current of the battery top cover, I sh is the actual leakage current of the battery top cover, and U is the voltage across the positive and negative terminal posts of the power battery;

[0077] When I sj ≥α, it is judged that the influence of the dust on the battery top cover leakage is too large, and the dust should be cleaned immediately;

[0078] When I sh ≥β, it is judged that the leakage current of the battery top cover is too large, and the top cover should be repaired immediately;

[0079] wherein, α and β are respectively the safety thresholds of the real-time leakage current and the actual leakage current of the battery top cover.

[0080] The present invention also provides a leakage safety detection system for the top cover of a power battery pack. The leakage safety detection system for the top cover of the power battery pack is used to execute the above-mentioned leakage safety detection method for the top cover of a power battery pack, and includes:

[0081] An insulation detection module, which is used to apply the positive end of a pulse signal source to the top cover of each battery in the battery pack to be detected. The negative end of the pulse signal source is connected to a detection resistor. The detection resistor is respectively connected in series with a current-limiting resistor and then electrically connected to the positive and negative electrode posts of the battery to form a top cover insulation detection circuit;

[0082] A circuit equivalent module, which is used to equivalent the insulating material between the top cover of the power battery and the positive and negative electrode posts as the insulation resistance of the positive and negative electrode posts, construct an equivalent insulation circuit model with the top cover insulation detection circuit, and calculate the insulation resistance of the positive and negative electrode posts according to the positive and negative voltages applied by the pulse signal source within the signal period and the detection voltage of the detection resistor in the detection circuit within the period, based on Kirchhoff's law;

[0083] A dust prediction module, which is used to obtain the historical working environment parameters and electrode post parameters of different battery packs, stamp time stamps to form a time series data set, perform time series segmentation on the time series data set by the sliding window method, establish a dust precipitation model, use the time series data set after segmentation at the current moment as the input of the model, and use the dust thickness of the positive and negative electrode posts at the next moment as the output of the model to train the model;

[0084] A dust resistance calculation module, which is used to use the environmental parameters and electrode post parameters of the battery at the current moment after being processed by the sliding window method as the input of the trained model, output the dust thickness of the positive and negative electrodes through the model, and calculate the resistance value of the dust according to the real-time environmental parameters and electrode post parameters of the battery, based on the influence of temperature and humidity on the conductivity of the dust respectively;

[0085] A leakage detection module, which is used to calculate the real resistance value of the insulating material between the positive and negative electrode posts and the top cover of the battery according to the detected insulation resistance of the positive electrode post, insulation resistance of the negative electrode post and the resistance value of the dust, calculate the actual leakage amount and the real-time leakage amount according to the real resistance value and the battery voltage, compare with the leakage threshold to judge the leakage situation, and take measures.

[0086] Compared with the prior art, the beneficial effects of the present invention are as follows: By applying a pulse signal source and a detection resistor to the top cover of each battery in the battery pack to be detected, an insulation detection circuit for the top cover is formed. The insulating material between the top cover of the power battery and the positive and negative electrode posts is equivalent to the insulation resistance of the positive and negative electrode posts, an equivalent insulation circuit model is constructed, the insulation resistance of the positive and negative electrode posts is calculated. By establishing a dust deposition model and training the model, the environmental parameters and pole parameters of the battery at the current moment are processed by the sliding window method and used as the input of the trained model. The dust thickness of the positive and negative electrodes is output by the model, and the resistance value of the dust is calculated according to the real-time environmental parameters and pole parameters of the battery. According to the detected insulation resistance of the positive electrode post, the insulation resistance of the negative electrode post, the resistance value of the dust, and the battery voltage, the actual leakage current and the real-time leakage current are calculated;

[0087] According to the present invention; an equivalent insulation circuit model is constructed to calculate the insulation resistance of the positive and negative electrode posts. The insulation resistance can be calculated by injecting the reflected wave voltage of the pulse signal source, which does not depend on the power battery voltage. It can also be measured when the power battery is disconnected or the voltage is very low. It can detect the insulation resistance in real time and accurately, and has high reliability and system compatibility. By establishing a dust deposition model, the dust thickness of the positive and negative electrodes is output by the model, and the dust resistance value is calculated in combination with the temperature and humidity, which can accurately predict the dust thickness and consider the influence of the environment on the resistance, helping to provide more accurate leakage detection. According to the detected insulation resistance of the positive electrode post, the insulation resistance of the negative electrode post, the resistance value of the dust, and the battery voltage, the actual leakage current and the real-time leakage current are calculated, which can truly reflect the insulation performance of the battery top cover, reflect the changes in the real-time and actual battery leakage current, and adjust the charge and discharge strategy and take necessary protection measures based on this. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 It is a schematic diagram of the overall method flow of the present invention;

[0089] Figure 2 It is a schematic diagram of the overall system structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0090] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0091] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those of ordinary skill in the field to which the present invention pertains. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "comprising" or "including" mean that the elements or objects appearing before this term cover the elements or objects listed after this term and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0092] Embodiment:

[0093] Please refer to Figure 1 , the present invention provides a technical solution:

[0094] A method for detecting the leakage safety of the top cover of a power battery pack, the specific steps include:

[0095] Step 1: Apply the positive terminal of a pulse signal source to the top cover of each battery in the battery pack to be detected. The negative terminal of the pulse signal source is connected to a detection resistor. The detection resistor is respectively connected in series with a current-limiting resistor and then electrically connected to the positive and negative electrode posts of the battery to form a top cover insulation detection circuit.

[0096] Due to changes such as humid heat cycling, temperature shock, salt spray corrosion, altitude, etc. brought about by weather and geographical location changes, it mainly causes thermal aging and cracking of the insulating material between the positive and negative electrode posts and the battery top cover. In summer, the temperature is relatively high, and the temperature of the power battery rises sharply. In winter, the temperature is relatively low, and the change in altitude will also generate a large temperature difference. The temperature difference causes the polymer of the insulating material to undergo thermal degradation in a high-temperature environment, shrink and become hard and brittle under low-temperature conditions, thereby accelerating the aging of the insulating material. Therefore, leakage behavior gradually occurs between the positive and negative electrode posts and the battery top cover.

[0097] In this embodiment, the top cover insulation detection circuit includes a pulse signal source U s , a detection resistor R f , a current-limiting resistor R 1 , a current-limiting resistor R 2 , a positive electrode post, and a negative electrode post. The pulse signal source U s includes a pulse positive output terminal and a pulse negative output terminal. The pulse positive output terminal is electrically connected to the battery top cover, and the pulse negative output terminal is electrically connected to one end of the detection resistor R f . One end of the detection resistor R f is respectively electrically connected to the current-limiting resistor R 1, current-limiting resistor R 2 is electrically connected to one end of the current-limiting resistor R 1 The other end of the current-limiting resistor R 2 is electrically connected to the positive terminal, and the other end of the current-limiting resistor R

[0098] Step 2: Equivalent the insulating material between the power battery top cover and the positive and negative terminals to the insulation resistance of the positive and negative terminals, construct an equivalent insulation circuit model with the top cover insulation detection circuit, apply positive and negative voltages applied by the pulse signal source within the signal period and the detection voltage of the detection resistance of the detection circuit within the period, and calculate the insulation resistance of the positive and negative terminals according to Kirchhoff's law.

[0099] In this embodiment, the equivalent insulation circuit model includes the positive terminal insulation resistance R p , the negative terminal insulation resistance R n and the top cover insulation detection circuit. One end of the positive terminal insulation resistance R p is electrically connected to the battery top cover and the negative terminal insulation resistance R n , and the other end of the positive terminal insulation resistance R p is electrically connected to the positive terminal. The other end of the negative terminal insulation resistance R n is electrically connected to the negative terminal.

[0100] The equivalent insulation circuit model injects a low-frequency and low-voltage detection signal with a certain amplitude and frequency into the power battery through the battery top cover, and calculates the insulation resistance of the positive and negative terminals according to the reflected wave voltage signal on the detection resistance. The specific measurement process is as follows: The pulse signal source generates a low-frequency detection signal, injects it into the power battery through the battery top cover, flows back to the top cover insulation detection circuit after passing through the positive and negative insulation resistances, and then flows back to the sampling resistance through the current-limiting resistor. At this time, a reflected wave voltage excited by the pulse signal source is generated on the sampling resistance, and the insulation resistance of the positive and negative terminals is calculated according to the magnitude of the reflected wave voltage.

[0101] The equivalent insulation circuit model can calculate the insulation resistance of the positive terminal and the negative terminal at the same time, and well solves the problem of low detection accuracy caused by insulation faults occurring simultaneously at the positive and negative terminals. This method calculates the insulation resistance through the reflected wave voltage of the injected pulse signal source, and can be independent of the power battery voltage. It can also be measured when the power battery is disconnected or the voltage is very low. Therefore, it has certain advantages in terms of reliability and system compatibility.

[0102] Kirchhoff's laws are two fundamental laws in circuit analysis, used to describe the distribution of current and voltage in a circuit, including Kirchhoff's current law and Kirchhoff's voltage law. In Kirchhoff's current law, at any node in the circuit, the sum of the currents entering the node is equal to the sum of the currents leaving the node. In Kirchhoff's voltage law, in any closed circuit, the sum of the voltages along the circuit path (loop) is zero, that is, the voltage rise and fall are equal.

[0103] In this embodiment, the specific steps for calculating the insulation resistance of the positive and negative electrode posts are as follows;

[0104] When the voltage applied by the pulse signal within the period is a positive voltage, according to Kirchhoff's law, the voltage across the detection resistor can be calculated, and the calculation formula is:

[0105] I f+ = I 1+ + I 2+

[0106] I f+ = I 3+ + I 4+

[0107] U = R n * I 4+ - R P * I 3+

[0108] U = R 1 * I 1+ - R 2 * I 2+

[0109] U s+ = R p * I 3+ + R 1 * I 1+ + R f * I f+

[0110] Among them, U s+ is the positive voltage applied by the pulse signal within the period, I 1+ , I 2+ , I 3+ , I 4+ , I f+ are respectively the currents passing through the current-limiting resistor R 1 , the current-limiting resistor R 2 , the insulation resistance R p of the positive electrode post, the insulation resistance R n of the negative electrode post, and the detection resistor R f ; U is the voltage across the positive and negative electrode posts of the power battery;

[0111] Since R 1 = R 2 = R, according to the above formula, the voltage across the detection resistor R f can be calculated. The voltage calculation formula is:

[0112]

[0113] where U f+ is the voltage across the detection resistor R when the positive voltage is applied within the period of the pulse signal f at both ends;

[0114] When the voltage applied within the period of the pulse signal is a negative voltage;

[0115] the voltage across the detection resistor R f can be calculated. The voltage calculation formula is:

[0116]

[0117] where U f- is the voltage across the detection resistor R when the negative voltage is applied within the period of the pulse signal f at both ends;

[0118] The calculation formula for the insulation resistance R p of the positive terminal post and the insulation resistance R n of the negative terminal post is:

[0119]

[0120] where R p is the insulation resistance of the positive terminal post, and R n is the insulation resistance of the negative terminal post.

[0121] Step 3: Obtain the historical working environment parameters, terminal post parameters of different battery packs, stamp time stamps to form a time series dataset, perform time series segmentation on the time series dataset by the sliding window method, establish a dust deposition model, use the time series dataset after segmentation at the current moment as the input of the model, and use the dust thickness of the positive and negative terminal posts at the next moment as the output of the model to train the model.

[0122] In this embodiment, the terminal post parameters include the terminal post material, terminal post area, and terminal post temperature;

[0123] The working environment parameters include temperature, humidity, and particulate matter concentration.

[0124] The material of the terminal post determines the interaction force between the surface of the terminal post and dust particles. The adsorption, adhesion, and accumulation characteristics of dust on battery terminal posts of different materials are different. The area of the terminal post directly affects the total area of dust adhesion, and thus affects the amount of dust accumulation. A larger surface area means more dust has the opportunity to adhere, while a smaller surface area reduces the total amount of dust adhesion. The terminal post temperature is a very important physical factor that directly affects the interaction between the surface and moisture and dust particles in the surrounding environment.

[0125] Temperature affects the mobility and sedimentation rate of dust particles. A higher temperature may lead to an increase in dust particles in the air or affect the adhesiveness of particles. Changes in humidity affect the adsorption and deposition characteristics of dust particles. Too high humidity may make dust particles more likely to aggregate and adhere. The particulate matter concentration is a factor that directly affects the dust deposition rate. The higher the dust concentration, the greater the amount of dust deposited per unit time.

[0126] In this embodiment, the calculation formula of the sliding window method is as follows:

[0127]

[0128] where X is the segmented time series dataset, and xn na is the n_a-th influencing factor in the time series dataset, t_i is the current moment, and n_c is the width of the sliding window;

[0129] The sliding window method divides the time series data into multiple windows of fixed length. The data within each window is used as an input sample. For example, the data of the nearest 30 days is used to predict the dust adhesion thickness on the 31st day. Each window contains environmental parameters and terminal post parameters at multiple times as the input of the model.

[0130] The sliding window method can effectively retain historical information and model the time series dependence of data through a long short-term memory neural network. The dust thickness on the battery terminal post is not only affected by the current environmental parameters and terminal post parameters, but also by the environmental parameters and terminal post parameters in the previous period. The sliding window can extract this dependence and obtain more accurate predictions based on historical data. Especially in a dynamic environment, the model can continuously adjust the prediction of the dust adhesion thickness at future moments to adapt to the trend of environmental changes.

[0131] The long short-term memory neural network is a special type of recurrent neural network that can effectively learn and remember temporal dependencies over long time spans. The thickness of dust adhesion is not only affected by current environmental parameters but also by environmental changes over a past period. For example, changes in temperature and humidity may affect the speed and amount of dust adhesion. The long short-term memory neural network can capture these long-term and short-term dependencies in the time series, making predictions more accurate. The environment where the battery terminal is located, such as temperature, humidity, dust concentration, etc., is usually dynamically changing. The long short-term memory neural network can identify the patterns of these environmental factors changing over time through historical data, thereby predicting the trend of dust accumulation.

[0132] Predicting dust accumulation is not just a simple linear relationship. There are complex non-linear relationships among environmental parameters such as temperature, humidity, dust concentration, etc. and between them and the terminal parameters. The long short-term memory neural network can handle these complex relationships through its deep non-linear structure and learning ability, which has more advantages than traditional linear regression or simple neural networks.

[0133] In this embodiment, the dust precipitation model is based on a long short-term memory neural network, and the long short-term memory neural network includes an input gate, a forget gate, and an output gate;

[0134] The equation expression of the forget gate is:

[0135] f t =δ(W f ·[h t-1 ,x t +b f )

[0136] Where f t is the current switch state of the forget gate, δ represents the sigmoid function, W f is the weight of the forget gate, b f is the bias parameter of the forget gate, h t-1 is the hidden state of the previous moment, and x t is the current data input switch;

[0137] Determines how much of the cell state at the previous moment needs to be retained to the current moment;

[0138] The equation expression of the input gate is:

[0139] i t =δ(W i ·[h t-1 ,x t +b i )

[0140] Where i tis the current switch state of the input gate, δ represents the sigmoid function, W i is the weight of the input gate, b i is the bias parameter of the input gate, h t-1 is the output hidden state at the previous moment, x t is the time series data set segmented at the current moment;

[0141]

[0142] Among them, the candidate cell state, tanh represents the hyperbolic tangent function, W c is the weight of the candidate cell, b c is the bias parameter of the candidate cell state, h t-1 is the hidden state at the previous moment, x t is the current data input switch;

[0143] Determines how much of the input data of the network at the current moment needs to be saved to the cell state;

[0144] The update equation is:

[0145]

[0146] Among them, C t the current cell state, C t-1 is the cell state at the previous moment;

[0147] The equation expression of the output gate is:

[0148] o t =(W o ·[h t-1 ,x t +b o )

[0149] h t =o t *tanh(C t )

[0150] Among them, o t is the current switch state of the output gate, δ represents the sigmoid function, W o is the weight of the output gate, b o is the bias parameter of the output gate, h t-1 is the hidden state at the previous moment, x t is the current data input switch, h t is the dust thickness of the positive and negative electrodes at the next moment;

[0151] Controls how much of the current cell state needs to be output to the current output value;

[0152] Among them, the mathematical expressions of the sigmoid function and the hyperbolic tangent function are as follows:

[0153]

[0154] Among them, δ(x γ ) is the sigmoid function, x γ is the input of the sigmoid function, tanh(C t ) is the hyperbolic tangent function, and C t is the input of the function.

[0155] Step 4: Take the environmental parameters and terminal post parameters of the battery at the current moment, which have been processed by the sliding window method, as the input of the trained model. Output the dust thicknesses of the positive and negative electrodes through the model, and calculate the resistance value of the dust according to the real-time environmental parameters and terminal post parameters of the battery, based on the effects of temperature and humidity on the conductivity of the dust respectively.

[0156] The accumulation of dust and the change of its conductivity may be precursors to the leakage of the battery pack. By first predicting the dust thickness and calculating the resistance value in combination with temperature and humidity data, the influence of dust on leakage can be accurately detected. By predicting the dust thickness and calculating its resistance value according to temperature and humidity conditions, the detection method can adapt to various environmental conditions, improving the versatility and reliability of the system.

[0157] The conductivity of dust is affected by humidity, especially dust containing salts or metal particles. In an environment with high humidity, moisture may form conductive channels between dust particles, so the conductivity will increase significantly.

[0158] In this embodiment, the specific steps of calculating the resistance value of the dust according to the effects of temperature and humidity on the conductivity of the dust respectively are as follows:

[0159] The formula for the influence of humidity on the conductivity of dust is:

[0160] σ s = σ 0 * (1 + k s * Sd)

[0161] Among them, σ s is the conductivity of the dust under the influence of humidity, σ 0 is the conductivity of the dust under standard temperature and humidity, k s is the humidity influence coefficient, and Sd is the humidity of the dust.

[0162] The change in temperature also affects the conductivity of dust. Usually, an increase in temperature will lead to an increase in the conductivity of substances.

[0163] The formula for the influence of temperature on the conductivity of dust is:

[0164]

[0165] Among them, σ w is the conductivity of dust under the influence of temperature, and σ 0 is the conductivity of dust under standard temperature and humidity, and k w is the humidity influence coefficient, and T h is the temperature of the dust;

[0166] The resistance value of the dust is calculated by the formula:

[0167]

[0168] Among them, R h is the resistance value of the dust, H h is the dust thickness, and S j is the area covered by the dust on the terminal post.

[0169] Step 5: According to the detected insulation resistance of the positive terminal post, the insulation resistance of the negative terminal post, and the resistance value of the dust, calculate the true resistance value of the insulating material between the positive and negative terminal posts and the battery top cover. According to the true resistance value and the battery voltage, calculate the actual leakage current and the real-time leakage current, compare with the leakage current threshold to judge the leakage situation, and take measures.

[0170] By calculating the true resistance value and combining the battery voltage and the resistance value of the dust, the leakage situation of the battery can be monitored in real time. The real-time leakage current calculation can accurately reflect the leakage situation under different working conditions such as temperature, humidity, dust accumulation and other factors.

[0171] However, by calculating the true resistance value of the insulation resistance of the positive and negative terminal posts and combining the battery voltage to calculate the actual resistance value, it reflects the actual leakage current of the power battery, which is not affected by the working conditions and is caused by the aging of the insulating material between the positive and negative terminal posts and the top cover.

[0172] Based on the monitoring of the real-time leakage current and the actual leakage current, the battery state can be analyzed more intelligently, and the charge and discharge strategy can be adjusted according to the leakage situation of the battery, and necessary protection measures can be taken.

[0173] In this embodiment, the formula for calculating the true resistance value of the positive and negative terminal posts is:

[0174] R zp = R p - R h

[0175] R zn = R n - R h

[0176] Among them, Rzp is the true resistance value of the insulation resistance of the positive terminal post, R zn is the true resistance value of the insulation resistance of the negative terminal post, R p is the insulation resistance of the positive terminal post, R n is the insulation resistance of the negative terminal post, R h is the resistance value of the dust;

[0177] The calculation formulas for the actual leakage current and the real-time leakage current are as follows:

[0178]

[0179] where, I sj is the real-time leakage current of the battery top cover, I sh is the actual leakage current of the battery top cover, and U is the voltage across the positive and negative terminal posts of the power battery;

[0180] When I sj ≥α, it is determined that the influence of the dust on the top cover of the battery on the top cover leakage is too large, and the dust should be cleaned immediately;

[0181] When I sh ≥β, it is determined that the leakage current of the battery top cover is too large, and the top cover should be repaired immediately;

[0182] where, α and β are respectively the safety thresholds of the real-time leakage current of the battery top cover and the actual leakage current of the battery top cover.

[0183] Please refer to Figure 2 , the present invention also provides a safety detection system for the leakage of the top cover of a power battery pack. The safety detection system for the leakage of the top cover of the power battery pack is used to execute the above-mentioned safety detection method for the leakage of the top cover of a power battery pack, and includes:

[0184] An insulation detection module, which is used to apply the positive terminal of a pulse signal source to the top cover of each battery in the battery pack to be detected. The negative terminal of the pulse signal source is connected to a detection resistor. The detection resistor is respectively connected in series with a current-limiting resistor and electrically connected to the positive and negative terminal posts of the battery to form a top cover insulation detection circuit;

[0185] A circuit equivalent module, which is used to equivalent the insulating material between the power battery top cover and the positive and negative terminal posts to the insulation resistance of the positive and negative terminal posts, construct an equivalent insulation circuit model with the top cover insulation detection circuit, and calculate the insulation resistance of the positive and negative terminal posts according to the positive and negative voltages applied by the pulse signal source within the signal period and the detection voltage of the detection resistor in the detection circuit within the period, based on Kirchhoff's law;

[0186] Dust prediction module, which is used to obtain the historical working environment parameters and terminal post parameters of different battery packs, stamp them with timestamps to form a time series data set, perform time series segmentation on the time series data set by the sliding window method, establish a dust precipitation model, use the segmented time series data set at the current moment as the input of the model, and use the dust thickness of the positive and negative terminal posts at the next moment as the output of the model to train the model;

[0187] Dust resistance calculation module, which is used to use the environmental parameters and terminal post parameters of the battery at the current moment after being processed by the sliding window method as the input of the trained model, output the dust thickness of the positive and negative poles through the model, and calculate the resistance value of the dust according to the real-time environmental parameters and terminal post parameters of the battery and the influence of temperature and humidity on the conductivity of the dust respectively;

[0188] Leakage detection module, which is used to calculate the true resistance value of the insulating material between the positive and negative terminal posts and the battery top cover according to the detected insulation resistance of the positive terminal post, insulation resistance of the negative terminal post and the resistance value of the dust, calculate the actual leakage current and real-time leakage current according to the true resistance value and the battery voltage, compare with the leakage threshold to judge the leakage situation, and take measures.

[0189] The above formulas are all calculated by taking the numerical values after removing the dimension. The formulas are obtained by collecting a large amount of data for software simulation to get a formula closest to the real situation. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0190] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, or by the combination of computer software and electronic hardware. Whether these functions are executed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0191] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units. They can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0192] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application, and all should be covered by the protection scope of this application.

Claims

1. A power battery pack top cover leakage safety detection method, characterized in that: The specific steps include: Step 1: Apply the positive end of the pulse signal source to the top cover of each battery in the battery pack to be tested, connect the negative end of the pulse signal source to the detection resistor, and the detection resistor is electrically connected to the positive and negative poles of the battery after being connected in series with the current limiting resistor to form a top cover insulation detection circuit; Step 2: The insulating material between the power battery top cover and the positive and negative poles is equivalent to the insulation resistance of the positive and negative poles, and an equivalent insulation circuit model is constructed with the top cover insulation detection circuit. The positive and negative voltages applied by the pulse signal source in the signal cycle and the detection voltage of the detection circuit in the cycle are compared, and the insulation resistance of the positive and negative poles is calculated according to Kirchhoff's law; Step 3: Obtain the historical working environment parameters and pole parameters of different battery packs and stamp them with timestamps to form a time series data set. Use the sliding window method to segment the time series data set, establish a dust precipitation model, use the segmented time series data set at the current moment as the input of the model, and use the dust thickness of the positive and negative poles at the next moment as the output of the model to train the model; Step 4: The current environmental parameters and pole parameters of the battery are processed by the sliding window method as the input of the trained model. The model outputs the dust thickness at the positive and negative electrodes. According to the real-time environmental parameters and pole parameters of the battery, the resistance value of the dust is calculated by the influence of temperature and humidity on the conductivity of the dust. Step 5: Calculate the true resistance of the insulating material between the positive and negative poles and the battery top cover based on the detected insulation resistance of the positive pole, the negative pole and the resistance of the dust. Calculate the actual leakage amount and the real-time leakage amount based on the true resistance and the battery voltage. Compare them with the leakage threshold to determine the leakage situation and take measures.

2. A power battery pack top cover leakage safety detection method according to claim 1, characterized in that: The top cover insulation detection circuit includes a pulse signal source U s , detection resistor R f , current limiting resistor R1, current limiting resistor R2, positive pole, negative pole, the pulse signal source U s It includes a pulse positive output terminal and a pulse negative output terminal, the pulse positive output terminal is electrically connected to the battery top cover, and the pulse negative output terminal is electrically connected to the detection resistor R f One end of the detection resistor R f One end of is electrically connected to one end of the current limiting resistor R1 and the current limiting resistor R2 respectively, the other end of the current limiting resistor R1 is electrically connected to the positive electrode column, and the other end of the current limiting resistor R2 is electrically connected to the negative electrode column.

3. A power battery pack top cover leakage safety detection method according to claim 1, characterized in that: The equivalent insulation circuit model includes the positive pole insulation resistance R p , Negative pole insulation resistance R n And the top cover insulation detection circuit, the positive pole insulation resistance R p One end of the battery is connected to the top cover and the negative pole by the insulation resistance R n Electrical connection, positive pole insulation resistance R p The other end is electrically connected to the positive pole, and the negative pole insulation resistance R n The other end is electrically connected to the negative electrode.

4. A power battery pack top cover leakage safety detection method according to claim 2, characterized in that: The specific steps of calculating the insulation resistance of the positive and negative poles are: When the voltage applied by the pulse signal during the period is a positive voltage, the voltage across the detection resistor can be calculated according to Kirchhoff's law. The calculation formula is: I f+ =I 1+ +I 2+ I f+ =I 3+ +I 4+ U=R n *I 4+ -R P *I 3+ U=R1*I 1+ -R2*I 2+ U s+ =R p *I 3+ +R1*I 1+ +R f *I f+ Among them, U s+ is the positive voltage applied by the pulse signal during the period, I 1+ ,I 2+ ,I 3+ ,I 4+ ,I f+ They are respectively the current limiting resistor R1, the current limiting resistor R2, and the positive column insulation resistance R when the pulse signal applies a positive voltage within the cycle. p , Negative pole insulation resistance R n and the detection resistor R f U is the voltage across the positive and negative poles of the power battery; Since R1=R2=R, according to the above formula, the detection resistor R can be calculated f The voltage at both ends, the voltage calculation formula is: Among them, U f+ When the positive voltage is applied by the pulse signal during the period, the detection resistor R f The voltage across the terminals; When the voltage applied by the pulse signal during the cycle is a negative voltage; The detection resistor R can be calculated f The voltage at both ends, the voltage calculation formula is: Among them, U f- When the pulse signal applies a negative voltage during the cycle, the detection resistor R f The voltage across the terminals; Positive column insulation resistance R p , Negative pole insulation resistance R n The calculation formula is: Among them, R p is the insulation resistance of the positive column, R n is the insulation resistance of the negative pole.

5. A power battery pack top cover leakage safety detection method according to claim 1, characterized in that: The pole parameters include pole material, pole area, and pole temperature; The working environment parameters include temperature, humidity, and particle concentration.

6. A power battery pack top cover leakage safety detection method according to claim 1, characterized in that: The calculation formula of the sliding window method is: Among them, X is the time series data set after segmentation, xn na is the nath influencing factor in the time series data set, ti is the current moment, and nc is the width of the sliding window.

7. A power battery pack top cover leakage safety detection method according to claim 1, characterized in that: The dust precipitation model is based on a long short-term memory neural network, which includes an input gate, a forget gate and an output gate; The equation of the forget gate is: f t =δ(W f ·[h t-1 ,x t ]+b f ) Among them, f t is the current switch state of the forget gate, δ represents the sigmoid function, W f is the forget gate weight, b f is the forget gate bias parameter, h t-1 is the hidden state at the previous moment, x t Input switch for current data; Determine how much of the unit state at the previous moment needs to be retained to the current moment; The equation for the input gate is: i t =δ(W i ·[h t-1 ,x t ]+b i ) Among them, i t is the current switch state of the input gate, δ represents the sigmoid function, W i is the input gate weight, b i is the input gate bias parameter, h t-1 is the output hidden state of the previous moment, x t is the time series data set after segmentation at the current moment; in, Candidate cell state, tanh represents the hyperbolic tangent function, W c is the candidate cell weight, b c is the candidate cell state bias parameter, h t-1 is the hidden state at the previous moment, x t Input switch for current data; Determine how much of the network's input data needs to be saved to the unit state at the current moment; The update equation is: Among them, C t Current cell state, C t-1 is the cell state at the previous moment; The output gate equation is: o t =(W o ·[h t-1 ,x t ]+b o ) h t =o t *tanh(C t ) Among them, t is the current switch state of the output gate, δ represents the sigmoid function, W o is the output gate weight, b o is the output gate bias parameter, h t-1 is the hidden state at the previous moment, x t is the current data input switch, h t is the dust thickness of the positive and negative poles at the next moment; Controls how much of the current unit state needs to be output to the current output value; Among them, the mathematical expressions of the sigmoid function and the hyperbolic tangent function are: Among them, δ(x γ ) is the sigmoid function, x γ is the input of sigmoid function, tanh(C t ) is the hyperbolic tangent function, C t Input to the function.

8. A power battery pack top cover leakage safety detection method according to claim 1, characterized in that: The specific steps of calculating the resistance value of dust according to the influence of temperature and humidity on the conductivity of dust are as follows: The effect of humidity on the conductivity of dust is calculated as follows: s s =σ0*(1+k s *Sd) Among them, σ s is the conductivity of dust under the influence of humidity, σ0 is the conductivity of dust at standard temperature and humidity, k s is the humidity influence coefficient, Sd is the humidity of dust; The effect of temperature on the conductivity of dust is calculated as follows: Among them, σ w is the conductivity of dust under the influence of temperature, σ0 is the conductivity of dust under standard temperature and humidity, k w is the humidity influence coefficient, T h is the temperature of the dust; The resistance value of dust is calculated as: Among them, R h is the resistance value of dust, H h is the dust thickness, S j It is the area covered by dust on the pole.

9. A power battery pack top cover leakage safety detection method according to claim 1, characterized in that: The calculation formula for the actual resistance of the positive and negative poles is: R zp =R p -R h R zn =R n -R h Among them, R zp is the actual resistance of the positive column insulation resistance, R zn is the actual insulation resistance of the negative pole, R p is the insulation resistance of the positive column, R n is the insulation resistance of the negative pole, R h is the resistance value of dust; The calculation formulas for the actual leakage and real-time leakage are: Among them, I sj is the real-time leakage of the battery cover, I sh is the actual leakage of the battery top cover, and U is the voltage at both ends of the positive and negative poles of the power battery; When I sj When ≥α, it is judged that the dust on the battery cover has too great an impact on the leakage of the cover, and the dust should be cleaned immediately; When I sh When ≥β, it is judged that the battery cover leakage is too large and the cover should be repaired immediately; Among them, α and β are the real-time leakage of the battery top cover and the safety threshold of the actual leakage of the battery top cover, respectively.

10. A power battery pack top cover leakage safety detection system, characterized in that: The power battery pack top cover leakage safety detection system is used to execute a power battery pack top cover leakage safety detection method according to any one of claims 1 to 9, comprising: An insulation detection module, wherein the insulation detection module is used to apply the positive end of a pulse signal source to the top cover of each battery in the battery pack to be detected, the negative end of the pulse signal source is connected to a detection resistor, and the detection resistor is respectively connected in series with a current limiting resistor and electrically connected to the positive and negative poles of the battery to form a top cover insulation detection circuit; A circuit equivalent module, which is used to equate the insulating material between the power battery top cover and the positive and negative poles to the insulation resistance of the positive and negative poles, and to construct an equivalent insulation circuit model with the top cover insulation detection circuit, and to calculate the insulation resistance of the positive and negative poles according to Kirchhoff's law by comparing the positive and negative voltages applied by the pulse signal source within the signal cycle with the detection voltage of the detection circuit during the cycle. A dust prediction module is used to obtain the historical working environment parameters of different battery packs and the pole parameters and print the timestamps to form a time series data set, perform time series segmentation on the time series data set by the sliding window method, establish a dust precipitation model, use the time series data set after segmentation at the current moment as the input of the model, and use the dust thickness of the positive and negative poles at the next moment as the output of the model to train the model; A dust resistance calculation module, which is used to process the current environmental parameters and pole parameters of the battery through a sliding window method as inputs of a trained model, output the dust thickness of the positive and negative electrodes through the model, and calculate the resistance value of the dust according to the real-time environmental parameters and pole parameters of the battery and the influence of temperature and humidity on the conductivity of the dust respectively; The leakage detection module is used to calculate the real resistance of the insulating material between the positive and negative poles and the battery top cover according to the detected positive pole insulation resistance, negative pole insulation resistance and dust resistance, calculate the actual leakage amount and the real-time leakage amount according to the real resistance and battery voltage, compare with the leakage threshold to determine the leakage situation, and take measures.

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