CN113296000A - Disassembly-free lithium battery rapid detection, diagnosis and analysis system and method - Google Patents
Disassembly-free lithium battery rapid detection, diagnosis and analysis system and method Download PDFInfo
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Abstract
The invention belongs to the technical field of battery detection, and discloses a disassembly-free rapid detection, diagnosis and analysis system for a lithium battery, which comprises an embedded Lunix device, which is connected with an expansion board, a touch screen and a Web client, the expansion board is connected with a power battery pack to be tested through a resistance load, the power battery pack to be tested is connected with a battery management system BMS, the embedded Linux equipment sends a control instruction to the expansion board through an I2C communication protocol to control the power battery pack to be tested to carry out constant current discharge, the battery management system BMS transmits the data in the discharging process to the expansion board in a CAN message mode, the expansion board transmits to the embedded Linux equipment through the SPI communication protocol, the embedded Linux equipment analyzes and processes the received CAN message to generate a diagnosis report, the Web content is displayed through the touch screen and can be uploaded to the cloud server through a TCP/IP protocol for query and analysis of the Web client.
Description
Technical Field
The invention relates to the technical field of power battery detection, in particular to a disassembly-free lithium battery rapid detection, diagnosis and analysis system and a rapid diagnosis and analysis method.
Background
At present, many domestic battery manufacturing enterprises and a plurality of enterprises on the market are closely connected with a battery detection system equipment industrial chain, and according to different types of batteries manufactured by battery manufacturers, a battery detection equipment supplier provides corresponding detection equipment which is applied to daily production, research and development of the battery manufacturers.
The power battery detection equipment in China starts late, the detection equipment industry starts to sprout from the 80 th year of the 20 th century, and through the gradual development of nearly 40 years, equipment manufacturers which are mature and have the independent research and development innovation capability are formed. For example, the Shenzhen Xinwei battery charge and discharge product comprises a single battery cell testing instrument and a battery module detecting instrument, can be applied to pulse charge and discharge testing, direct current internal resistance testing and capacity testing of a battery module of a power battery pack, and can be matched with an upper computer operating system to complete detection of a battery to be tested. The power battery detection equipment of the domestic multifunctional electric vehicle also supports charge-discharge cycle testing, battery cycle life testing and working condition simulation of the single battery and the battery module. The battery doctor who develops at the power battery experimental institute of Shanghai engineering technology university also can realize power battery charge-discharge test, but equipment volume is great and the function is single, can't diagnose battery module except that battery performance failure mode.
Although the types of the domestic power battery detection equipment are rich, the internal core important components still need to be supported by imported manufacturers, the functions of detection instruments of different manufacturers can be found to be single and repeated, and the detection functions are mainly required for laboratory research or scientific research. The product is high in price, large in size, specialized in operation and redundant in function of the detection scene of the power battery in use. Under the current demand that the capacity of large-batch new energy automobile power batteries is reduced and the retired batteries are utilized in a gradient manner, a detection device is needed to detect the core parameters of the power batteries, the abnormal problems of the power battery modules are accurately positioned by establishing a battery module failure diagnosis tree, a quick diagnosis result is obtained in an upper computer operating system, and meanwhile, the detection device is light and portable enough, reasonable in price and supports secondary development and rich battery algorithm introduction. Therefore, the portable detection device capable of rapidly testing the performance of the power battery module has great market potential.
Disclosure of Invention
The invention provides a disassembly-free lithium battery rapid detection, diagnosis and analysis system and a rapid diagnosis and analysis method, which solve the problems of high price, large volume, redundant functions of an in-use power battery detection scene and the like of the conventional power battery detection product.
The invention can be realized by the following technical scheme:
a disassembly-free lithium battery rapid detection, diagnosis and analysis system comprises an embedded Lunix device, the embedded Lunix equipment is connected with an expansion board, a touch screen and a Web client, the expansion board is connected with a power battery pack to be tested through a resistance load, the power battery pack to be tested is connected with a battery management system BMS, the embedded Linux equipment sends a control instruction to the expansion board through an I2C communication protocol to control the power battery pack to be tested to perform constant current discharge, the battery management system BMS transmits the data in the discharging process to the expansion board in a CAN message mode, the expansion board is transmitted to the embedded Linux equipment through the SPI communication protocol, the embedded Linux equipment analyzes and processes the received CAN message to generate a diagnosis report, the Web content is displayed through the touch screen and can be uploaded to the cloud server through a TCP/IP protocol for query and analysis of the Web client.
Furthermore, the embedded Lunix device adopts a raspberry pi as a processor, the expansion board comprises a clock module, a digital-to-analog converter, an analog-to-digital converter, a CAN signal receiving module, an expansion port and a constant current module, the clock module, the digital-to-analog converter, the CAN signal receiving module and the expansion port are connected with the raspberry pi, the constant current module is connected with the power battery pack to be tested through a load, the clock module is used for providing a timestamp for the operation of the disassembly-free lithium battery rapid detection, diagnosis and analysis system, the digital-to-analog converter is used for simulating and outputting a control voltage input signal serving as the constant current module, asking for electric energy from the battery pack and releasing the electric energy into the load of a loop to complete set constant current discharge detection.
Further, a Raspberry Pi Desktop system is installed in the Raspberry group, and the software architecture of the embedded Lunix device adopts an MVC three-layer architecture mode and is expanded to support a B/S architecture mode.
Further, the diagnosis report comprises CAN communication failure detection, BMS channel failure detection, single battery direct current internal resistance detection and self-discharge rate detection, and internal resistance consistency detection.
A rapid diagnosis and analysis method based on the disassembly-free rapid detection, diagnosis and analysis system of the lithium battery comprises CAN communication failure detection, BMS channel failure detection, single battery internal resistance detection and self-discharge rate detection, and internal resistance consistency detection, wherein,
judging whether CAN communication is invalid or not by detecting communication life information of the BMS;
by means of a wire changing tool, sequentially and correspondingly connecting each BMS channel and each single battery in the power battery pack to be detected according to the serial numbers, recording data from each BMS channel at the moment, sequentially and correspondingly connecting each BMS channel and each single battery in the power battery pack to be detected according to the serial numbers in a staggered manner, recording data from each BMS channel at the moment, comparing whether the data obtained twice are consistent or not, if so, judging that the BMS channels are normal, otherwise, judging that the BMS channels are invalid;
calculating the direct current internal resistance R of each single battery in the power battery pack to be tested by using the following equation,
wherein, Delta UOAnd Δ UPRespectively representing voltage changes caused by ohmic internal resistance and polarization internal resistance of the battery; i represents a discharge current; u shapeCShowing the power battery pack to be tested after the moment of discharging by using the disassembly-free lithium battery rapid detection, diagnosis and analysis system of claim 1A battery voltage; u shapeAThe system is characterized in that the system is used for rapidly detecting, diagnosing and analyzing the lithium battery without disassembly according to claim 1, and represents the battery voltage before the power battery pack to be detected is discharged;
calculating the self-discharge rate K of each single battery in the power battery pack to be tested by using the following equation,
wherein K represents the self-discharge rate of the battery, mV/d; OCV1Showing the open-circuit voltage, V, corresponding to each single battery after the first test discharge of the power battery pack to be tested by using the disassembly-free lithium battery rapid detection, diagnosis and analysis system of claim 1; OCV2Showing the open-circuit voltage V corresponding to each single battery after the power battery pack to be tested is stored for a period of time and the second test discharge of the power battery pack to be tested is finished by using the disassembly-free lithium battery rapid detection diagnosis analysis system of claim 1; Δ represents the storage time, d;
firstly, calculating the average direct current internal resistance at the same time according to the direct current internal resistance of each single battery, thereby calculating the corresponding resistance standard deviation sigma at the moment, then comparing the difference value of the direct current internal resistance and the average direct current internal resistance of each single battery with 3 sigma, and if the difference value is more than 3 sigma, carrying out early warning, thereby completing the internal resistance consistency detection.
Further, it is detected whether the CAN communication is normal by checking whether communication life information contained in the 8 th byte of 186040F3 in the kokubary BMS system information service communication protocol is continuous.
The beneficial technical effects of the invention are as follows:
1. the equipment is simple and portable, the test is convenient, and the large-current constant-current discharge can be carried out on the battery pack to be tested. Compared with conventional test equipment such as Arbin, blue electricity and the like, the test equipment has the advantages that diagnosis functions including direct current internal resistance diagnosis, self-discharge efficiency analysis, internal resistance consistency analysis and the like are added on the basis of testing, and the test equipment is lighter, lower in cost and wider in application scene.
2. The data of each single battery in the testing process can be collected, the data can be uploaded to the cloud server, and visual testing results can be checked from a webpage.
3. The remote communication function can upload the test data to the cloud server, so that the diagnosis result can be traced on the basis of the diagnosis function, and effective prediction and early warning can be performed.
Drawings
FIG. 1 is a schematic diagram of the general structure of the present invention;
FIG. 2 is a schematic view of the structure of the expansion board of the present invention;
FIG. 3 is a schematic diagram of the B/S architecture mode of the present invention;
FIG. 4 is a schematic diagram of a partial family BMS system information service communication protocol according to the present invention;
fig. 5 is a schematic view illustrating the corresponding connection of BMS channels and respective unit cells in a battery pack according to the present invention;
fig. 6 is a schematic view of a volt-ampere characteristic curve of the direct current internal resistance of the battery.
Detailed Description
The following detailed description of the preferred embodiments will be made with reference to the accompanying drawings.
As shown in fig. 1, the present invention provides a disassembly-free lithium battery rapid detection, diagnosis and analysis system, which comprises an embedded Lunix device, the embedded Lunix device is connected with an expansion board, a touch screen and a Web client, the expansion board is connected with a power battery pack to be tested through a resistance load, the power battery pack to be tested is connected with a battery management system BMS, the embedded Linux equipment sends a control instruction to the expansion board through an I2C communication protocol to control the power battery pack to be tested to carry out constant current discharge, the battery management system BMS transmits the data in the discharging process to the expansion board in a CAN message mode, the expansion board transmits to the embedded Linux equipment through the SPI communication protocol, the embedded Linux equipment analyzes and processes the received CAN message to generate a diagnosis report, the Web content is displayed through the touch screen and can be uploaded to the cloud server through a TCP/IP protocol for query and analysis of the Web client. The diagnosis report comprises CAN communication failure detection, BMS channel failure detection, single battery direct current internal resistance detection and self-discharge rate detection, internal resistance consistency detection and the like.
The rapid diagnosis and analysis system is used for carrying out constant-current discharge detection on the power battery pack to be detected, during the test process, the embedded Lunix device receives a CAN message sent by a battery management system BMS, analyzes the content of the CAN message according to a message protocol, and comprises the voltage, the discharge current, the discharge time and the like of the power battery pack to be detected, transmits bottom layer data to a front-end touch screen for display through a Model View Controller (MVC) architecture for short, displays the single discharge detection result to a user in an icon form, and simultaneously, an operator CAN set a discharge working condition through the interface to control a detector to discharge the power battery module. The rapid diagnosis and analysis system disclosed by the invention is characterized in that besides the traditional embedded MVC framework, a Browser/Server B/S mode for short is also designed in an expanded manner, data can be uploaded to a cloud Server, battery detection data can be checked from a WEB Browser side, battery diagnosis and calculation can be carried out, wherein a diagnosis algorithm mainly comprises failure judgment and classification of various power battery modules, and all detection results can generate an Excel format diagnosis report.
The rapid diagnosis and analysis system comprises hardware equipment and a software system, wherein the structural block diagram of the whole system is shown in figure 1, the hardware equipment comprises embedded Linux equipment, an expansion board and the like, and the software system is divided into an equipment end system and a remote system. In the hardware equipment, embedded Linux equipment sends a control instruction to an expansion board through an I2C communication protocol to control the power battery pack to be tested to perform constant current discharge, and in the discharge process, message data are transmitted to a CAN bus controller in the expansion board in a CAN communication mode through a battery management system BMS, and CAN messages are received in the embedded Linux equipment through an SPI communication protocol. The embedded Linux equipment completes analysis, storage, preliminary calculation and display of the CAN message after receiving the CAN message, simultaneously, data CAN be uploaded to a cloud server through a TCP/IP protocol besides local storage, and a remote system manages the uploaded detection data, provides data page display, remotely controls an operation interface and further battery diagnosis algorithm, and finally generates a rapid diagnosis report.
Specifically, the embedded Lunix device adopts a raspberry pi as a processor, the expansion board comprises a clock module connected with the raspberry pi, a digital-to-analog converter, an analog-to-digital converter, a CAN signal receiving module, an expansion port and a constant current module connected with the digital-to-analog converter and the analog-to-digital converter, the constant current module is connected with a power battery pack to be tested through a load, the clock module is used for providing a timestamp for operation of the disassembly-free lithium battery rapid detection, diagnosis and analysis system, the digital-to-analog converter is used for simulating and outputting a control voltage input signal serving as the constant current module, electric energy is required for the battery pack and is released into the load of a loop, and set constant current discharge detection is completed.
The rapid diagnosis and analysis system selects Raspberry pi (Raspberry pi 3B) as a processor of embedded Linux equipment, serves as project code running equipment of a whole local detection part, and is connected with an expansion board to control constant current discharge of a power battery pack to be detected and CAN message receiving. The raspberry pie can run a complete operating system, and the system architecture of Python and C language used in the system is convenient to run in the raspberry pie. Moreover, the raspberry is provided with more comprehensive interfaces, and common interfaces such as USB-host, RJ45, HDMI and SD card readers are provided, so that the problem of a human-computer operation interface can be directly solved by connecting a matched display screen. Meanwhile, the system is not limited to on-site detection, the data are required to be uploaded to a cloud server to be subjected to depth detection, the raspberry group can be connected with a WIFI network or a network cable, data connection between on-site equipment and a cloud platform can be completed through a TCP/IP communication mode, and additional expansion is omitted. The Pin 40 is connected with an expansion board in the system, and communication interfaces including SPI, I2C and the like in the Pin meet the requirement of communication control.
The Raspberry group can support various different types of systems, including Raspbian, Debian GNU, Fedora, Ubuntu and the like, the system most suitable for the Raspberry group is the Raspberry Pi OS, an official deeply customized hardware driver and software program are distributed for the Raspberry group, and a matched desktop version not only has a convenient and fast human-computer interaction interface, but also is internally provided with three-million preinstallation packages such as common tools, a compiling environment of Python3 and the like. The Raspberry Pi Desktop system is installed by comprehensively considering the Raspberry group of the system.
The expansion board is designed according to system requirements and limitations of a raspberry group, and a design structure block diagram is shown in fig. 2, and the expansion board mainly comprises a clock module for providing a timestamp, a digital-to-analog converter (DAC) for taking analog output as control voltage input of a constant current module, an analog-to-digital converter (ADC) for receiving an analog signal, a CAN signal receiving module, a constant current module and an expansion port 485 module for subsequent further development. The expansion board provides a DAC (digital-to-analog converter) and an ADC (analog-to-digital converter) port which are not used by a raspberry, electric energy CAN be charged for a power battery pack to be tested through a DAC port and released into a loop load to finish set constant current discharge detection, meanwhile, a CAN signal receiving module is used as a control chip of a CAN to transmit collected data messages into the raspberry group in test engineering, and preparation is made for data display and analysis in a follow-up software system, wherein the DAC and ADC port are as follows:
1. clock module
The raspberry pi does not have a hardware real-time clock module, especially the system needs to add a timestamp to each message sent by the BMS with high accuracy to identify the states of the batteries at different times in the detection process, and the congenital of the raspberry pi is not enough to keep the clock frequency on the board unstable, so that a clock chip needs to be added on an expansion board. The clock module used by the system is DS1307, is a low-power-consumption full BCD code clock calendar real-time clock chip with 56 bytes of non-volatile RAM, addresses and data are transmitted through a two-wire bidirectional serial bus, the chip can provide information such as seconds, minutes, hours and the like, the number of days of each month can be automatically adjusted, and the leap year compensation function is realized.
2. Digital-to-analog converter (DAC)
The main board of the raspberry pi is not provided with a digital-to-analog converter (DAC) port, and the expansion board of the system needs analog output as the input of the control voltage of a constant current power supply board, so that the port needs to be added. For the subsequent control with wider voltage range, 5V power supply is selected instead of 3.3V power supply. Requiring a chip capable of supporting I2C communication, the system selects to use MCP4725 chip, which is a low-power consumption, high-precision, single-channel, 12-bit buffer voltage output digital-to-analog converter, and the user can write DAC input and configuration into the memory by using I2C communication interface commands to realize digital-to-analog conversion function.
3. Analog-digital conversion interface (ADC)
There is no analog-to-digital conversion interface (ADC) on the raspberry device to read the analog signal, as in the DAC port above, the port in the expansion board to which the ADC is added accepts the analog signal. The range of the voltage received by the system is wide, and a 5V power supply is selected for supplying power. The chip selected by the system is the ADS1115 with I2C communication, the chip is a high-precision analog-to-digital converter with 16-bit resolution, an ultra-small lead-free QFN package is adopted, in addition, the precision, the power consumption and the simplicity in implementation are considered in the design process, and the system can be applied to the scenes of portable instruments, battery monitoring and temperature measurement.
4. CAN signal receiving module
The raspberry group CAN not directly receive the CAN message sent by the BMS, and a CAN receiving chip for realizing SPI communication needs to be additionally arranged in the expansion board. The system selects a CAN control chip MCP2515 which CAN receive and send standard data frames, extended data frames and remote frames, has an SPI serial communication interface which accords with industrial standard communication, and CAN communicate with a raspberry group.
5. Constant current module
An ADC module, a DAC module, a clock module and a CAN message receiving module are integrated in the expansion board, and a constant current module is needed to control constant current discharge of the battery pack. The constant current module selected by the system is an LTC3779 constant current and constant voltage power supply board of the United states Linear Tech, is the model with the highest voltage in power supply products of the company, is a high-performance voltage reduction-boosting type switching voltage stabilization controller, and can work under the condition that the input voltage is higher than, lower than or equal to the output voltage. The device employs a constant frequency current mode architecture, providing a phase-lockable frequency of up to 600kHz, while an input/output constant current loop provides support for battery charging.
As for the resistance load, in the process of constant current discharge of the power battery pack to be tested by the detection system, the electric energy discharged by the power battery pack to be tested needs to be converted into resistance heat energy in the test loop for consumption, so that a load resistor with a proper specification is needed as a carrier of the discharge electric energy in the detection process. The load selected by the system is determined according to the upper limit of the test of the detector, the highest output voltage is 100V, the maximum output current is 50A, and the highest output power is 5 KW. The load resistor of the output end can be selected to be 2 ohms according to ohm's law, the model of the selectable resistor is ZX26-2.2, and the high-voltage direct current power lithium battery resistor is safe and reliable, has the advantages of large capacity, corrosion resistance, no induction, no contact resistance, stable resistance value, error of +/-7.5% of total resistance value, long service life, is superior to the replacement of an old resistor, is widely suitable for various discharge test scenes, and is suitable for an in-use power lithium battery rapid diagnosis system.
The hardware system of the system mainly comprises a raspberry group, an expansion board, a touch display screen, a load resistor, a battery pack to be tested, a BMS (battery management system) and a mobile power supply. The raspberry pi, the expansion board, the touch display screen and the mobile power supply are integrated in the portable shell, and the rest parts are connected in series with the DuPont wire through the lead. The raspberry pie is fixed with the touch screen through four bolts and is connected with an HDMI interface through a USB; the expansion board is connected with the raspberry pie through a PIN foot, and two bolts are additionally arranged for fixing; the constant current modules except the constant current modules in the expansion board are all concentrated on the lower part of the raspberry pie, and the constant current modules are connected with the ADC and the DAC module in the expansion board through DuPont lines; and the interface with an external circuit is led out through the DC end of the constant current module, and is internally connected with a safety switch in series. The raspberry pi and the touch screen are powered by a 5V/3A mobile power supply in the portable shell.
The software part of the system is written based on C language and Python language, and a design module with a three-layer architecture is adopted. The three-layer architecture comprises a Data Access Layer (DAL), a Business Logic Layer (BLL) and a presentation layer (UI), wherein the data access layer is written by using C language, and the business logic layer and the presentation layer are written by using Python language. The top device side operation interface (UI layer) is used for providing a user parameter command input interface, visual display of detection data and basic operation of the device; the business logic (BLL) is used for processing all business processes, receiving parameter commands transmitted from the UI layer and calling the data access layer, and has the functions of transmitting parameter instructions, decoding CAN messages, storing detection data and the like; the Data Access Layer (DAL) controls the operation of various modules according to different protocols by using commands transmitted from the service logic layer, and can also receive parameters transmitted from the modules. There is also a parameter class common to the UI layer and the BLL layer, which is used simultaneously as a transport carrier.
Based on the original three-layer architecture, the system is also expanded to support a B/S architecture mode, and the architecture is shown in FIG. 3. The original data access layer and the original service logic layer are reserved, the presentation layer is changed into a back-end service built by a FLASK framework, and data are uploaded to a cloud platform server in an FTP mode based on a TCP/IP communication mode. And receiving and storing data by a service built by the server in the cloud platform, writing the battery diagnosis algorithm into logic processing, and enabling a user to view detection data from a WEB browser end after the data is thrown out from the front end.
The FLASK framework is a lightweight application framework compiled by using Python, has strong expansibility and flexibility, and can be rapidly deployed on cloud services to serve as a service end; the cloud server selects an Aliskive ECS server, and the server and cloud computing and other services are more complete; js progressive framework is selected for front-end WEB service, efficient data binding and flexible component system are realized through API, and rapid forming of a website interface can be realized by matching with Element UI and Echar; data transmitted between the equipment end and the Server are transmitted in an FTP mode, the raspberry pie of the equipment end is sent as a Server end, and the Server is received and stored to an appointed path as a Client end. The battery algorithm is deployed in the back end of the cloud service, the server calls data and then calculates, and the result is sent to the front end to be displayed and checked.
Generally, the power battery system comprises a single battery cell, a BMS (battery management system), a bus bar, a connecting wire harness and the like, the reliability of a detection result can be improved by researching failure types of the power battery system in the battery detection process, and more effective early warning and recovery suggestions are provided for battery modules of different failure types. The reuse and failure detection of the power battery have corresponding safety evaluation standards UL1974, which specify the detection items in the evaluation of the power battery with the battery in a gradient manner. Aiming at the situation that the rapid detection of the rapid equipment of the power lithium battery is used and the application is suitable for the field, the detection which can be realized is compared and analyzed with the UL1974 standard, and the fault test which can be realized by the rapid detector is listed. According to the detection classification of the standard UL1974, the invention also provides a rapid diagnosis and analysis method based on the disassembly-free lithium battery rapid detection, diagnosis and analysis system, which is mainly divided into three aspects, namely BMS equipment faults, external connection faults and single battery abnormity, wherein the BMS equipment faults comprise CAN communication failure and BMS channel failure, the external connection faults refer to busbar contact abnormity, and the single battery abnormity comprises battery internal resistance abnormity, self-discharge rate abnormity, internal resistance consistency analysis and the like.
The analysis of the battery data is obtained from the CAN messages, so that the CAN communication in the BMS must achieve the purpose of normally and quickly receiving and sending the messages, and each parameter requirement of the battery in the messages CAN truly reflect the state of the battery in the experimental process. And (4) starting to diagnose the battery module under the normal detection, wherein the data used in the process comes from the CAN message sent by the BMS with normal function. The diagnosis of the battery module comprises external connection faults and single battery abnormity, wherein the battery connection faults refer to loose connection between pole bolts and CAN lines in single batteries, and the connection faults are mistakenly judged as data abnormity caused by the reason of the battery without eliminating the faults, so that the faults are preferably eliminated. And finally, under the condition that all the detection conditions are normal, calculating the direct current internal resistance, the open-circuit voltage and the like of all the single batteries according to the measured change relation between the battery voltage and the current, and obtaining the diagnosis and evaluation result of the battery after determining the internal resistance threshold value.
1. Failure of CAN communication
The system judges whether CAN communication is invalid or not by detecting the communication life information of the BMS, CAN select to detect the communication life information of the BMS to judge whether communication is abnormal or not, in the actual detection example, the communication protocol of the Korland BMS system information service is adopted, wherein a message containing communication content is shown in figure 4, the 8 th byte containing the communication life information at 186040F3 CAN be obtained, and whether the BMS communication is normal or not is detected by checking the data continuity.
2. BMS channel failure
With the help of the frock of changing wire, correspond the connection according to the sequence number earlier with each battery cell in waiting to examine the power battery group in each BMS passageway earlier, as shown in FIG. 5, the data that comes from each BMS passageway this moment of record, correspond each battery cell in waiting to examine the power battery group in each BMS passageway again in proper order the dislocation of number in proper order and connect, the data that comes from each BMS passageway this moment of record, compare whether the data that obtains twice are unanimous, if, judge that the BMS passageway is normal, otherwise judge that the BMS passageway is invalid, specifically as follows:
a trade line frock for passageway can be according to actual need and decide, and former BMS passageway is connected with battery module according to the serial number, then trades the line device and will connect the order and push back one according to this and connect, and last one and first are connected again. Specifically, the information that the BMS first channel should be the battery pack having battery No. 1 is converted into the battery No. 2, and so on, the information that the BMS24 channel receives becomes the battery pack having battery No. 1. Compared with the data of the battery channel before replacement, if the BMS channel and the connecting line are not failed, the front and the rear groups of data are consistent, and only the serial number of the data of each group of monomers is pushed backwards by one bit, so that the specific data content is not changed.
3. External connection failure
In a power battery system, most of the battery cores of the power battery module are connected through bolts, and after a period of use, the fastening bolts are possibly oxidized and fall off or loosened due to vibration of the bolts of a pilot. The occurrence of such a phenomenon directly results in the generation of a large amount of heat at the junction, and even in severe cases, in the explosion of the battery pack due to combustion. In addition, battery bolts used for a long time can be loosened, so that the connection between a BMS data acquisition line and a pole is not firm, abnormal jumping change of data can be obtained due to the phenomenon, the healthy battery is judged to be an aging abnormal battery, the system carries out fault diagnosis on the bolt connection at the bus bar, and analysis is mainly carried out on the basis of acquired message data.
4. Battery cell anomaly detection
The voltage of the battery drops rapidly in the early stage during the discharging process, and the voltage begins to drop slowly in the later stage. As shown in fig. 6, this phenomenon is caused by the fact that the ohmic internal resistance of the cell generates the internal partial pressure of the cell in the early stage, which causes the voltage of the cell to drop rapidly, and the electrochemical reaction occurs mainly due to the polarization internal resistance of the cell in the later stage, which causes the voltage to change slowly. According to the characteristics of the internal flow resistance of the battery in the whole life cycle of the battery, the voltage change caused by the ohmic internal resistance is far larger than the polarization internal resistance, and in the design and detection of the system, the two internal resistances are merged and are returned to the direct-current internal resistance R for calculation.
Calculating the direct current internal resistance R of each single battery in the power battery pack to be tested by using the following equation,
wherein, Delta UOAnd Δ UPRespectively representing voltage changes caused by ohmic internal resistance and polarization internal resistance of the battery; i represents a discharge current; u shapeCThe system is characterized by showing the battery voltage after the moment of discharging the power battery pack to be tested by using the disassembly-free lithium battery rapid detection, diagnosis and analysis system of claim 1; u shapeAThe system is characterized in that the system is used for rapidly detecting, diagnosing and analyzing the lithium battery without disassembly according to claim 1, and represents the battery voltage before the power battery pack to be detected is discharged;
calculating the self-discharge rate K of each single battery in the power battery pack to be tested by using the following equation,
wherein K represents the self-discharge rate of the battery, mV/d; OCV1Showing the end of the first test discharge of the power battery pack to be tested by using the disassembly-free lithium battery rapid detection, diagnosis and analysis system of claim 1Then, the open circuit voltage, V, corresponding to each single battery; OCV2After the power battery pack to be tested is stored for a period of time, the disassembly-free lithium battery rapid detection, diagnosis and analysis system is utilized to carry out secondary test and discharge on the power battery pack to be tested, and then the open-circuit voltage V corresponding to each single battery is represented; Δ represents the storage time, d;
firstly, calculating the average direct current internal resistance at the same time according to the direct current internal resistance of each single battery, thereby calculating the corresponding resistance standard deviation sigma at the moment, then comparing the difference value of the direct current internal resistance and the average direct current internal resistance of each single battery with 3 sigma, and if the difference value is more than 3 sigma, carrying out early warning, thereby completing the internal resistance consistency detection.
Although specific embodiments of the present invention have been described above, it will be appreciated by those skilled in the art that these are merely examples and that many variations or modifications may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is therefore defined by the appended claims.
Claims (6)
1. The utility model provides a lithium cell short-term test diagnosis analytic system who exempts from to disassemble which characterized in that: the system comprises embedded Lunix equipment, wherein the embedded Lunix equipment is connected with an expansion board, a touch screen and a Web client, the expansion board is connected with a power battery pack to be tested through a resistance load, the power battery pack to be tested is connected with a battery management system BMS, the embedded Linux equipment sends a control instruction to the expansion board through an I2C communication protocol to control the power battery pack to be tested to perform constant current discharge, the battery management system BMS transmits data in the discharge process to the expansion board in a CAN message mode, the expansion board transmits the data to the embedded Linux equipment through an SPI communication protocol, the embedded Linux equipment analyzes and processes the received CAN message to generate a diagnosis report, the diagnosis report is displayed through the touch screen and CAN also be uploaded to a cloud server through a TCP/IP protocol for query and analysis of the Web client.
2. The disassembly-free lithium battery rapid detection, diagnosis and analysis system as recited in claim 1, wherein: the embedded Lunix device adopts a raspberry pi as a processor, the expansion board comprises a clock module, a digital-to-analog converter, an analog-to-digital converter, a CAN signal receiving module, an expansion port and a constant current module, the clock module, the digital-to-analog converter, the CAN signal receiving module and the expansion port are connected with the raspberry pi, the constant current module is connected with a power battery pack to be detected through a load, the clock module is used for providing a timestamp for the operation of the disassembly-free lithium battery rapid detection, diagnosis and analysis system, the digital-to-analog converter is used for simulating and outputting a control voltage input signal serving as the constant current module, asking for electric energy from the battery pack and releasing the electric energy into the load of a loop, and the set constant current discharge detection is completed.
3. The disassembly-free lithium battery rapid detection, diagnosis and analysis system as recited in claim 2, wherein: the Raspberry Pi Desktop system is installed in the Raspberry group, and the software architecture of the embedded Lunix device adopts an MVC three-layer architecture mode and is expanded to support a B/S architecture mode.
4. The disassembly-free lithium battery rapid detection, diagnosis and analysis system as recited in claim 1, wherein: the diagnosis report comprises CAN communication failure detection, BMS channel failure detection, single battery direct current internal resistance detection and self-discharge rate detection, and internal resistance consistency detection.
5. A rapid diagnostic and analytical method based on the disassembly-free lithium battery rapid detection, diagnostic and analytical system of claim 1, characterized in that: comprises CAN communication failure detection, BMS channel failure detection, single battery direct current internal resistance detection and self-discharge rate detection, and internal resistance consistency detection, wherein,
judging whether CAN communication is invalid or not by detecting communication life information of the BMS;
by means of a wire changing tool, sequentially and correspondingly connecting each BMS channel and each single battery in the power battery pack to be detected according to the serial numbers, recording data from each BMS channel at the moment, sequentially and correspondingly connecting each BMS channel and each single battery in the power battery pack to be detected according to the serial numbers in a staggered manner, recording data from each BMS channel at the moment, comparing whether the data obtained twice are consistent or not, if so, judging that the BMS channels are normal, otherwise, judging that the BMS channels are invalid;
calculating the direct current internal resistance R of each single battery in the power battery pack to be tested by using the following equation,
wherein, Delta UOAnd Δ UPRespectively representing voltage changes caused by ohmic internal resistance and polarization internal resistance of the battery; i represents a discharge current; u shapeCThe voltage of each single battery after the power battery pack to be tested is discharged by the disassembly-free lithium battery rapid detection, diagnosis and analysis system of claim 1; u shapeAShowing the voltage of each single battery before the power battery pack to be tested is discharged by the disassembly-free lithium battery rapid detection, diagnosis and analysis system of claim 1;
calculating the self-discharge rate K of each single battery in the power battery pack to be tested by using the following equation,
wherein K represents the self-discharge rate of the battery, mV/d; OCV1Showing the open-circuit voltage, V, corresponding to each single battery after the first test discharge of the power battery pack to be tested by using the disassembly-free lithium battery rapid detection, diagnosis and analysis system of claim 1; OCV2Showing the open-circuit voltage V corresponding to each single battery after the power battery pack to be tested is stored for a period of time and the second test discharge of the power battery pack to be tested is finished by using the disassembly-free lithium battery rapid detection diagnosis analysis system of claim 1; Δ represents the storage time, d;
firstly, calculating the average direct current internal resistance at the same time according to the direct current internal resistance of each single battery, thereby calculating the corresponding resistance standard deviation sigma at the moment, then comparing the difference value of the direct current internal resistance and the average direct current internal resistance of each single battery with 3 sigma, and if the difference value is more than 3 sigma, carrying out early warning, thereby completing the internal resistance consistency detection.
6. The rapid diagnostic analysis method of disassembly-free lithium battery rapid detection diagnostic analysis system according to claim 5, characterized in that: whether the CAN communication is normal is detected by checking whether communication life information contained in the 8 th byte of 186040F3 in the kobuski BMS system information service communication protocol is continuous.
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