Device and method for rapidly analyzing dynamic consistency of battery pack

Abstract

The invention discloses equipment and a method for quickly analyzing the dynamic consistency of a battery pack, and belongs to the technical field of battery testing. The equipment comprises a large-current excitation module, a voltage acquisition module and a control and processing module. The core of the system is that the control and processing module controls the large-current excitation module to apply transient large-current charging and discharging excitation to the battery pack to be detected; meanwhile, the voltage acquisition module synchronously acquires the dynamic voltage transient response of each single battery cell in the battery pack in the excitation period; and the control and processing module calculates a consistency evaluation index according to the voltage change amplitude and / or the voltage change curve form of each battery cell, and compares the consistency evaluation index with a preset threshold value so as to quickly judge the consistency state of the battery pack. According to the method, effective evaluation of the consistency of the battery pack can be completed in a non-destructive and short time (usually in seconds to minutes), and the technical problem that a traditional method needs to test or disassemble the battery pack for a long time is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery testing, in particular to a device and method for quickly evaluating the consistency of single battery cells in a battery pack. BACKGROUND

[0002] In power battery or energy storage battery systems such as lithium-ion batteries used in groups, the consistency between single batteries is crucial, which directly affects the overall performance, life and safety of the battery pack. A battery pack with poor consistency will quickly decay in available capacity and has the risk of overcharging and overdischarging, which is prone to cause thermal runaway.

[0003] Currently, the evaluation of battery pack consistency mostly adopts static parameter methods, such as measuring the static open-circuit voltage and internal resistance of each battery cell. However, the static open-circuit voltage cannot reflect the performance differences of the battery under dynamic working conditions; while the internal resistance test can provide some dynamic information, but the test current is usually small, which is difficult to excite the performance differences of the battery cells under real high-current working conditions, and the test results are greatly affected by the contact resistance.

[0004] A more accurate method is to perform complete charge and discharge cycle tests and record the capacity and voltage curves of each battery cell. However, this method takes a very long time, several hours to several tens of hours, which cannot meet the needs of production line offline detection or on-site rapid screening. In addition, it is unrealistic and destructive to disassemble a single battery cell for testing for a battery pack that has been packaged.

[0005] Therefore, there is an urgent need in the art for a technology and device that can quickly and accurately evaluate the dynamic consistency of a battery pack without disassembling the battery pack. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art and provide a device and method for quickly analyzing the dynamic consistency of a battery pack, which can effectively evaluate the consistency of single battery cells inside the battery pack in a short time through a non-destructive method. The purpose of the present application is to overcome the shortcomings of the prior art and provide a device and method for quickly analyzing the dynamic consistency of a battery pack, which can effectively evaluate the consistency of single battery cells inside the battery pack in a short time through a non-destructive method. TECHNICAL SOLUTION

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A device for quickly analyzing the dynamic consistency of a battery pack includes three core modules: 1. A high-current excitation module: This module can be a programmable high-current DC power supply or an electronic load, which is used to apply a short-time, high-intensity (e.g. 1C-3C) charge and discharge current pulse to the battery pack under test. This high-current excitation can quickly amplify the voltage response differences between battery cells with different performance; 2. Voltage acquisition module: This module is a multi-channel high-precision voltage acquisition unit, whose acquisition lines are directly connected to the positive and negative poles of each single cell in the battery pack. It needs to have high sampling rate and high synchronism to ensure that it can accurately capture the voltage transient change process of all cells at the moment of excitation; 3. Control and processing module: usually an embedded system or industrial computer, integrated with control software and data analysis algorithms. It is responsible for coordinating the entire test process: sending instructions to start large current excitation, synchronously triggering voltage acquisition, receiving and storing voltage data. In the data processing stage, it executes the core algorithm: (1). Calculate the voltage change ΔV = V_end - V_start of each cell within a fixed excitation time (such as 1 minute); (2). Statistically analyze the ΔV values of all cells, calculate their standard deviation (σ), range (Max-Min), or coefficient of variation (CV = σ / μ); (3). Compare the calculated statistical quantities (consistency evaluation indexes) with the preset empirical threshold or standard threshold to give qualitative or quantitative judgments of "good consistency" or "poor consistency"; (4). In addition, auxiliary judgments can also be made by comparing the parallelism and separation degree of the dynamic voltage curves of each cell.

[0008] Advantages Compared with the prior art, the advantages of the present application are: 1. Fast and efficient: the entire test process is completed within a few seconds to a few minutes, much faster than traditional full-cycle charge and discharge tests, and is very suitable for off-line detection on production lines and rapid diagnosis on site; 2. Non-destructive: the test does not require disassembly of the battery pack and does not damage the battery itself, maintaining the structural integrity of the battery pack; 3. Dynamic and accurate: through large current excitation, the performance differences of the cells under real working conditions can be effectively excited, and the voltage transient response is more reflective of the dynamic consistency of the battery than static parameters; 4. Intuitive and reliable: by analyzing the dispersion of voltage change, the consistency state of the battery pack can be intuitively and quantitatively given, and the judgment result is accurate and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is the overall system block diagram of the device described in the present application.

[0010] Figure 2 is a flowchart of the method described in the present application.

[0011] Figure 3 is a typical dynamic voltage response curve comparison diagram when the battery pack has good consistency and poor consistency. DETAILED DESCRIPTION

[0012] The application will be described in detail below with reference to the accompanying drawings and specific examples. Examples

[0013] Reference Figure 1 The device of the application comprises a control and processing module (1), a large-current excitation module (2), and a voltage acquisition module (3). The battery pack (4) to be tested is composed of a plurality of single cells (41, 42,..., 4n) connected in series; During the implementation test: 1. Connect the output end of the large-current excitation module (2) to the total positive (B+) and total negative (B-) ends of the battery pack (4); 2. Connect the multi-channel acquisition lines of the voltage acquisition module (3) to the positive and negative electrodes of each single cell (41, 42,..., 4n), respectively; 3. The operator sets the test parameters, such as the excitation current size 2C discharge and the excitation duration 60 seconds, through the human-machine interface of the control and processing module (1); 4. Start the test. The control and processing module (1) synchronously sends instructions to start the large-current excitation module (2) for constant-current discharge, and simultaneously triggers the voltage acquisition module (3) to start high-speed synchronous acquisition of the voltages of all the cells; 5. After the excitation is completed, the voltage acquisition module (3) uploads the acquired voltage data to the control and processing module (1); 6. The control and processing module (1) executes the analysis program: (1). Extract the voltage values V_t0 and V_t1 of each cell at the start time (t0) and the end time (t1) of the excitation; (2). Calculate the voltage variation ΔV = V_t1 - V_t0 of each cell; (3). Calculate the standard deviation σ of all ΔV values; (4). Compare σ with the preset threshold value (for example, 5mV). If σ < 5mV, it is determined that the battery pack consistency is good; if σ ≥ 5mV, it is determined that there is a problem with the battery pack consistency, and an alarm is reported on the display module; 7. The test is completed, and the device generates a test report; Through the above process, the dynamic consistency of the battery pack can be quickly and effectively evaluated within 1 minute.

Claims

1. A device for rapid analysis of the dynamic consistency of a battery pack, characterized in that, include: The high-current excitation module is used to connect to the total positive and total negative terminals of the battery pack under test and to provide short-term high-current charge and discharge excitation. A voltage acquisition module is used to connect to each individual cell in the battery pack to synchronously acquire the voltage transient response data of all cells during the excitation. The control and processing module is electrically connected to the high-current excitation module and the voltage acquisition module, respectively. It is used to control the start and stop of the excitation and the parameters, receive and process the voltage transient response data, calculate the consistency evaluation index by analyzing the voltage dynamic changes of each cell, and output the consistency judgment result.

2. The device according to claim 1, characterized in that, The high-current excitation module generates a charging and discharging current with a rate of 0.5C to 5C, and the excitation duration is between 10 seconds and 300 seconds.

3. The device according to claim 1 or 2, characterized in that, The consistency evaluation index calculated by the control and processing module is the statistical dispersion of the voltage change (ΔV) of each individual cell within the set excitation time window.

4. The device according to claim 3, characterized in that, The statistical dispersion includes the standard deviation, range, or coefficient of variation of the voltage variation (ΔV).

5. The device according to claim 1, characterized in that, The control and processing module is also used to plot the dynamic voltage curve of each individual cell during excitation, and to make a consistency judgment by comparing the morphological similarity or voltage change rate of the dynamic voltage curve.

6. The device according to claim 1, characterized in that, The device also includes a display module for displaying the consistency judgment result, the dynamic voltage curve of each cell, and the consistency evaluation index.

7. A rapid analysis method for the dynamic consistency of a battery pack based on the device according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Connect the device to the battery pack under test; (2) Control the high current excitation module to apply a charge-discharge excitation of a preset intensity and duration; (3) The voltage data of all individual cells during the excitation process are collected synchronously through the voltage acquisition module; (4) Process the collected voltage data and calculate the voltage change (ΔV) of each cell during the excitation period. (5) Calculate the consistency evaluation index based on the voltage change (ΔV) of all cells; (6) Compare the consistency evaluation index with the preset threshold. If the index is better than the threshold, the battery pack is judged to have good consistency; otherwise, the battery pack is judged to have a problem with consistency.

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