CN111413629B - Short circuit monitoring method, system and device for single battery in power battery - Google Patents

Abstract

The invention relates to the technical field of battery short circuit monitoring, in particular to a method, a system and a device for monitoring the short circuit of a single battery in a power battery, and aims to solve the problem of accurately monitoring whether the single battery in the power battery is short-circuited. According to the method, the deviation degree of each single voltage relative to the overall distribution of all single voltages in a certain time period is calculated, and whether the single batteries are short-circuited is judged according to the deviation degrees.

Description

Short circuit monitoring method, system and device for single cells in power batteries

Technical field

The invention relates to the technical field of battery short-circuit monitoring, and in particular to a method, system and device for short-circuit monitoring of single cells in a power battery.

Background technique

The power battery in an electric vehicle may experience thermal runaway due to a short circuit during the charging and discharging process, thereby endangering the safety of the power battery and passengers in the electric vehicle. For example: when the power battery is in extreme states such as overcharge, over-discharge, high-temperature charging, and over-current, the single cells (cells) in the power battery may produce dendrites. If the dendrites produced by a single cell are similar to If other single cells are in contact, these single cells may be short-circuited, and the temperature of the short-circuited single cell will increase due to excessive short-circuit current. If the temperature of a short-circuited single cell is too high, it may also cause other surrounding single cells to also short-circuit and increase their temperature, thereby increasing the risk of thermal runaway of the power battery. In addition, when conductive particles are entrained in the power battery, the separator is damaged, and local stress is excessive, it may also cause a short circuit in the single battery and increase the risk of thermal runaway.

At present, the short circuit monitoring method of single cells in power batteries is mainly to monitor whether short circuit occurs in the power battery through the battery management system in the electric vehicle when using small current to charge the power battery and when the electric vehicle is stationary. When using high current power battery When charging and when the electric vehicle is running, it is impossible to monitor whether the single cells in the power battery are short-circuited.

Accordingly, a new power battery short circuit test solution is needed in this field to solve the above problems.

Contents of the invention

In order to overcome the above defects, the present invention is proposed to provide a method, system and device for short circuit monitoring of single cells in a power battery that solve or at least partially solve the problem of how to accurately monitor whether a single cell in a power battery is short-circuited.

In the first aspect, a method for short-circuit monitoring of single cells in a power battery is provided, which method includes:

Obtain the corresponding cell voltage of each cell in the power battery received within a certain period of time, and calculate the corresponding overall distribution of each cell voltage within the certain period of time relative to all received cell voltages. degree of deviation;

According to the corresponding deviation of each cell voltage, it is determined whether a cell short circuit occurs in the power battery; if so, an alarm message is output.

Among them, "obtain the corresponding cell voltage of each single cell in the power battery received within a certain period of time, and calculate the respective corresponding cell voltages of each single cell voltage within the certain period of time relative to all received cells. The step of "Deviation of the overall voltage distribution" specifically includes: taking the preset battery short-circuit monitoring time as the starting point of time, obtaining the power battery received within the preset first time period after the preset battery short-circuit monitoring time. The first cell voltage corresponding to each cell in the cell is calculated, and the first deviation degree corresponding to each first cell voltage relative to the overall distribution of all first cell voltages is calculated.

Among them, the step of "determining whether a single cell short circuit occurs in the power battery according to the corresponding deviation degree of each cell voltage" specifically includes: judging whether the first deviation degrees corresponding to all first cell voltages are less than Or equal to the preset deviation threshold; if so, it is determined that no single cell short circuit occurs in the power battery.

Wherein, the step of "determining whether a single cell short circuit occurs in the power battery according to the corresponding deviation of each cell voltage" further includes:

When the first deviation corresponding to a certain first cell voltage is greater than the preset deviation threshold, the preset battery short-circuit monitoring time is used as the starting point of time to obtain the preset battery short-circuit monitoring time. The second cell voltage corresponding to each cell in the power battery received within the previously preset second time period is calculated separately for each second cell voltage relative to all second cell voltages. The second degree of deviation from the overall distribution;

According to the first degree of deviation and the second degree of deviation, determine whether a single cell short circuit occurs in the power battery;

The preset second duration is longer than the preset first duration.

Among them, the step of "determining whether a single cell short circuit occurs in the power battery based on the first degree of deviation and the second degree of deviation" specifically includes:

Arrange the second degree of deviation and the first degree of deviation according to the order of the cell voltage receiving time to obtain a deviation degree array;

Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain a linear regression curve equation and a linear fitting degree;

Determine whether the linear fitting degree is greater than the preset first fitting degree threshold; if so, obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation

Determine whether the slope value is greater than a preset slope threshold; if so, it is determined that a single cell short circuit has occurred in the power battery; if not, it is determined that a single cell short circuit has not occurred in the power battery.

The method also includes: if the linear fitting degree is less than or equal to a preset first fitting degree threshold, performing polynomial fitting calculation on the deviation degrees in the deviation degree array to obtain a second-order polynomial fitting curve equation. and polynomial fit;

Determine whether the polynomial fitting degree is greater than a preset second fitting degree threshold;

The coefficient corresponding to the 2nd-order term in the term fitting curve equation and determine whether the coefficient is greater than zero; if so, it is determined that a single cell short circuit has occurred in the power battery; if not, it is determined that a single cell short circuit has occurred in the power battery short circuit;

If the polynomial fitting degree is less than or equal to the preset second fitting degree threshold, it is determined that a single cell short circuit has not occurred in the power battery.

Among them, the step of "respectively calculating the deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within the certain period of time" specifically includes:

The degree of deviation is calculated according to the method shown in the following formula:

The CellVolt _{i_j} is the cell voltage of the j-th cell in the power battery received at the i-th time within the certain period of time, and the devi_i_j is the deviation corresponding to the cell voltage CellVolt _{i_j} , so The AvgVolt _i is the average value of all cell voltages received at the i-th moment within the certain period of time, and the StdVolt _i is the standard deviation of all the cell voltages received at the i-th moment within the certain period of time.

Wherein, before the step of "respectively calculating the deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within the certain period of time", the method also includes:

Obtain each operating current of the power battery received within the certain period of time;

Arrange the working currents in order of current reception time to obtain a working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current;

Obtain the working current whose difference is greater than the preset difference threshold and the data reception time corresponding to the working current;

Obtain the corresponding cell voltage of each cell received within a certain time range before and after the data reception time within the certain period of time and delete them, and then perform the step "calculate respectively according to the remaining cell voltages" Describes the deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within a certain period of time."

In the second aspect, a short circuit monitoring system for single cells in a power battery is provided. The system includes:

Deviation degree calculation device, which is configured to obtain the corresponding cell voltage of each cell in the power battery received within a certain period of time, and respectively calculate the corresponding cell voltage of each cell voltage within the certain period of time relative to Deviation from the overall distribution of voltages received across all cells;

A battery short circuit judgment device is configured to judge whether a single cell short circuit occurs in the power battery based on the corresponding deviation of each cell voltage; if so, output an alarm message.

Wherein, the deviation calculation device includes a first deviation calculation module, and the first deviation calculation module is configured to perform the following operations: taking the preset battery short-circuit monitoring time as the starting point of time, obtaining the preset time at the preset time. The first cell voltage corresponding to each cell in the power battery received within the preset first time period after the battery short-circuit monitoring moment is calculated, and the corresponding first cell voltage of each first cell voltage relative to all the The first degree of deviation of the overall distribution of cell voltage.

Wherein, the battery short-circuit determination device includes a first short-circuit determination module, and the first short-circuit determination module is configured to perform the following operations: determine whether the first deviation degrees corresponding to all first cell voltages are less than or equal to a preset value. Deviation threshold; if yes, it is determined that no single cell short circuit occurs in the power battery.

Wherein, the deviation calculation device includes a second deviation calculation module, and the battery short circuit judgment device includes a second short circuit judgment module;

The second deviation calculation module is configured to use the preset battery short-circuit monitoring time as a time starting point to obtain the power received within a preset second time period before the preset battery short-circuit monitoring time. The corresponding second cell voltage of each single cell in the battery is calculated separately, and the corresponding second deviation degree of each second cell voltage relative to the overall distribution of all second cell voltages is calculated; wherein, the preset The second duration is greater than the preset first duration;

The second short circuit determination module is configured to determine, when the first short circuit determination module determines that the first deviation corresponding to a certain first cell voltage is greater than the preset deviation threshold, based on the first deviation degree and the second deviation degree to determine whether a single cell short circuit occurs in the power battery.

Wherein, the second short circuit judgment module is configured to perform the following operations:

Arrange the second deviation degree and the first deviation degree in order of the cell voltage receiving time to obtain a deviation degree array;

Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain a linear regression curve equation and a linear fitting degree;

Determine whether the linear fitting degree is greater than a preset first fitting degree threshold; if so, obtain the slope value of the corresponding linear regression curve according to the linear regression calculation result;

Determine whether the slope value is greater than a preset slope threshold; if so, it is determined that a single cell short circuit has occurred in the power battery; if not, it is determined that a single cell short circuit has not occurred in the power battery.

Wherein, the second short circuit judgment module is configured to perform the following operations:

If the linear fitting degree is less than or equal to the preset first fitting degree threshold, polynomial fitting calculation is performed on the deviation degrees in the deviation degree array to obtain a second-order polynomial fitting curve equation and a polynomial fitting degree. ;

Determine whether the polynomial fitting degree is greater than a preset second fitting degree threshold;

If the polynomial fitting degree is greater than the preset second fitting degree threshold, then obtain the coefficient corresponding to the 2nd order term in the 2nd order polynomial fitting curve equation and determine whether the coefficient is greater than zero; if so, determine the The power battery has a single cell short circuit; if not, it is determined that the power battery does not have a single cell short circuit;

If the polynomial fitting degree is less than or equal to the preset second fitting degree threshold, it is determined that a single cell short circuit has not occurred in the power battery.

The method further includes that the deviation calculation device is configured to perform the following operations:

The degree of deviation is calculated according to the method shown in the following formula:

Wherein, the CellVolt _{i_j} is the cell voltage of the j-th cell in the power battery received at the i-th time within the certain period of time, and the devi_i_j is the deviation degree corresponding to the cell voltage CellVolt _{i_j} , the AvgVolt _i is the mean value of all cell voltages received at the i-th moment within the certain period of time, and the StdVolt _i is the standard deviation of all the cell voltages received at the i-th moment within the certain period of time.

The method further includes that the deviation calculation device is configured to perform the following operations:

Obtain each operating current of the power battery received within the certain period of time;

Arrange the working currents in order of current reception time to obtain a working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current;

Obtain the working current whose difference is greater than a preset difference threshold and obtain the data reception time corresponding to the working current;

Obtain the corresponding cell voltage of each cell received within a certain time range before and after the data reception time within the certain period of time and delete them, and then perform the step "calculate respectively according to the remaining cell voltages" Describes the deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within a certain period of time."

In a third aspect, a storage device is provided, in which a plurality of program codes are stored, and the program codes are adapted to be loaded and run by a processor to perform any one of the above-mentioned short circuits of single cells in a power battery. Monitoring methods.

In a fourth aspect, a control device is provided. The control device includes a processor and a storage device. The storage device is adapted to store a plurality of program codes. The program codes are adapted to be loaded and run by the processor to perform any of the above. A short circuit monitoring method for single cells in a power battery.

Solution 1. A short circuit monitoring method for single cells in a power battery, characterized in that the method includes:

Obtain the corresponding cell voltage of each cell in the power battery received within a certain period of time, and calculate the corresponding overall distribution of each cell voltage within the certain period of time relative to all received cell voltages. degree of deviation;

According to the corresponding deviation of each cell voltage, it is determined whether a cell short circuit occurs in the power battery; if so, an alarm message is output.

Option 2. The method for short-circuit monitoring of single cells in a power battery according to Option 1, characterized by: “obtaining the corresponding cell voltage of each single cell in the power battery received within a certain period of time, and calculating respectively. The step of "determining the deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within a certain period of time" specifically includes:

Taking the preset battery short-circuit monitoring time as the starting point, obtain the first unit corresponding to each single cell in the power battery received within the preset first time period after the preset battery short-circuit monitoring time. cell voltage, respectively calculate the corresponding first deviation degree of each first cell voltage relative to the overall distribution of all first cell voltages.

Option 3. The short-circuit monitoring method of single cells in a power battery according to Option 2, which is characterized in that, "According to the corresponding deviation degree of each of the single cell voltages, it is determined whether a single cell short circuit occurs in the power battery. "The steps specifically include:

It is determined whether the first deviations corresponding to all the first cell voltages are less than or equal to the preset deviation threshold; if so, it is determined that no single cell short circuit has occurred in the power battery.

Option 4. The short-circuit monitoring method of single cells in a power battery according to Option 3, which is characterized in that, "According to the corresponding deviation degree of each of the single cell voltages, it is determined whether a single cell short circuit occurs in the power battery. ” steps further include:

When the first deviation corresponding to a certain first cell voltage is greater than the preset deviation threshold, the preset battery short-circuit monitoring time is used as the starting point of time to obtain the preset battery short-circuit monitoring time. The second cell voltage corresponding to each cell in the power battery received within the previously preset second time period is calculated separately for each second cell voltage relative to all second cell voltages. The second degree of deviation from the overall distribution;

According to the first degree of deviation and the second degree of deviation, determine whether a single cell short circuit occurs in the power battery;

Wherein, the preset second duration is longer than the preset first duration.

Option 5. The method for monitoring the short circuit of a single cell in a power battery according to Option 4, which is characterized in that "based on the first degree of deviation and the second degree of deviation, determine whether a single cell short circuit occurs in the power battery." The steps specifically include:

Arrange the second degree of deviation and the first degree of deviation according to the order of the cell voltage receiving time to obtain a deviation degree array;

Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain a linear regression curve equation and a linear fitting degree;

Determine whether the linear fitting degree is greater than a preset first fitting degree threshold; if so, obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation;

Determine whether the slope value is greater than a preset slope threshold; if so, it is determined that a single cell short circuit has occurred in the power battery; if not, it is determined that a single cell short circuit has not occurred in the power battery.

Option 6. The method for short-circuit monitoring of single cells in a power battery according to Option 5, which is characterized in that it also includes:

If the linear fitting degree is less than or equal to the preset first fitting degree threshold, polynomial fitting calculation is performed on the deviation degrees in the deviation degree array to obtain a second-order polynomial fitting curve equation and a polynomial fitting degree. ;

Determine whether the polynomial fitting degree is greater than a preset second fitting degree threshold;

If the polynomial fitting degree is greater than the preset second fitting degree threshold, then obtain the coefficient corresponding to the 2nd order term in the 2nd order polynomial fitting curve equation and determine whether the coefficient is greater than zero; if so, determine the The power battery has a single cell short circuit; if not, it is determined that the power battery does not have a single cell short circuit;

If the polynomial fitting degree is less than or equal to the preset second fitting degree threshold, it is determined that a single cell short circuit has not occurred in the power battery.

Option 7. The short circuit monitoring method for single cells in a power battery according to any one of Option 1 to 6, characterized in that, "respectively calculate the corresponding relative voltage of each single cell voltage relative to the received voltage within the certain period of time." The steps to obtain the "deviation degree of the overall distribution of voltages of all cells" specifically include:

The degree of deviation is calculated according to the method shown in the following formula:

Wherein, the CellVolt _{i_j} is the cell voltage of the j-th cell in the power battery received at the i-th time within the certain period of time, and the devi_i_j is the deviation degree corresponding to the cell voltage CellVolt _{i_j} , the AvgVolt _i is the mean value of all cell voltages received at the i-th moment within the certain period of time, and the StdVolt _i is the standard deviation of all the cell voltages received at the i-th moment within the certain period of time.

Option 8. The method for short-circuit monitoring of single cells in a power battery according to any one of Schemes 1 to 6, characterized in that in "respectively calculate the corresponding relative voltage of each cell voltage within the certain period of time Before the step of "determining the deviation degree of the overall distribution of voltages of all cells received", the method further includes:

Obtain each operating current of the power battery received within the certain period of time;

Arrange the working currents in order of current reception time to obtain a working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current;

Obtain the working current whose difference is greater than the preset difference threshold and the data reception time corresponding to the working current;

Obtain the corresponding cell voltage of each cell received within a certain time range before and after the data reception time within the certain period of time and delete them, and then perform the step "calculate respectively according to the remaining cell voltages" Describes the deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within a certain period of time."

Solution 9. A short circuit monitoring system for single cells in a power battery, characterized in that the system includes:

Deviation degree calculation device, which is configured to obtain the corresponding cell voltage of each cell in the power battery received within a certain period of time, and respectively calculate the corresponding cell voltage of each cell voltage within the certain period of time relative to Deviation from the overall distribution of voltages received across all cells;

A battery short circuit judgment device is configured to judge whether a single cell short circuit occurs in the power battery based on the corresponding deviation of each cell voltage; if so, output an alarm message.

Option 10. The short circuit monitoring system for single cells in a power battery according to Option 9, characterized in that the deviation calculation device includes a first deviation calculation module, and the first deviation calculation module is configured to execute The following actions:

Taking the preset battery short-circuit monitoring time as the starting point, obtain the first unit corresponding to each single cell in the power battery received within the preset first time period after the preset battery short-circuit monitoring time. cell voltage, respectively calculate the corresponding first deviation degree of each first cell voltage relative to the overall distribution of all first cell voltages.

Option 11. The short-circuit monitoring system for single cells in power batteries according to Option 10, characterized in that the battery short-circuit judgment device includes a first short-circuit judgment module, and the first short-circuit judgment module is configured to perform the following operations :

It is determined whether the first deviation degrees corresponding to all the first cell voltages are less than or equal to the preset deviation threshold value; if so, it is determined that no single cell short circuit has occurred in the power battery.

Option 12. The short-circuit monitoring system for single cells in the power battery according to Option 11, characterized in that the deviation calculation device includes a second deviation calculation module, and the battery short-circuit judgment device includes a second short-circuit judgment module ;

The second deviation calculation module is configured to use the preset battery short-circuit monitoring time as a time starting point to obtain the power received within a preset second time period before the preset battery short-circuit monitoring time. The corresponding second cell voltage of each single cell in the battery is calculated separately, and the corresponding second deviation degree of each second cell voltage relative to the overall distribution of all second cell voltages is calculated; wherein, the preset The second duration is greater than the preset first duration;

The second short-circuit determination module is configured to determine, when the first short-circuit determination module determines that the first deviation corresponding to a certain first cell voltage is greater than the preset deviation threshold, based on the first deviation degree and the second deviation degree to determine whether a single cell short circuit occurs in the power battery.

Option 13. The short-circuit monitoring system for single cells in the power battery according to Option 12, characterized in that the second short-circuit judgment module is configured to perform the following operations:

Arrange the second degree of deviation and the first degree of deviation according to the order of the cell voltage receiving time to obtain a deviation degree array;

Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain the linear regression curve equation and linear fitting degree;

Determine whether the linear fitting degree is greater than a preset first fitting degree threshold; if so, obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation;

Determine whether the slope value is greater than a preset slope threshold; if so, it is determined that a single cell short circuit has occurred in the power battery; if not, it is determined that a single cell short circuit has not occurred in the power battery.

Option 14. The short-circuit monitoring system for single cells in the power battery according to Option 13, characterized in that the second short-circuit judgment module is configured to perform the following operations:

If the linear fitting degree is less than or equal to the preset first fitting degree threshold, polynomial fitting calculation is performed on the deviation degrees in the deviation degree array to obtain a second-order polynomial fitting curve equation and a polynomial fitting degree. ;

Determine whether the polynomial fitting degree is greater than a preset second fitting degree threshold;

If the polynomial fitting degree is greater than the preset second fitting degree threshold, then obtain the coefficient corresponding to the 2nd order term in the 2nd order polynomial fitting curve equation and determine whether the coefficient is greater than zero; if so, determine the The power battery has a single cell short circuit; if not, it is determined that the power battery does not have a single cell short circuit;

If the polynomial fitting degree is less than or equal to the preset second fitting degree threshold, it is determined that a single cell short circuit has not occurred in the power battery.

Option 15. The short circuit monitoring system for single cells in a power battery according to any one of Option 9 to 14, characterized in that the deviation calculation device is configured to perform the following operations:

The degree of deviation is calculated according to the method shown in the following formula:

Wherein, the CellVolt _{i_j} is the cell voltage of the j-th cell in the power battery received at the i-th time within the certain period of time, and the devi_i_j is the deviation degree corresponding to the cell voltage CellVolt _{i_j} , the AvgVolt _i is the mean value of all cell voltages received at the i-th moment within the certain period of time, and the StdVolt _i is the standard deviation of all the cell voltages received at the i-th moment within the certain period of time.

Option 16. The short circuit monitoring system for single cells in a power battery according to any one of Option 9 to 14, characterized in that the deviation calculation device is configured to perform the following operations:

Obtain each operating current of the power battery received within the certain period of time;

Arrange the working currents in order of current reception time to obtain a working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current;

Obtain the working current whose difference is greater than a preset difference threshold and obtain the data reception time corresponding to the working current;

Obtain the corresponding cell voltage of each cell received within a certain time range before and after the data reception time within the certain period of time and delete them, and then perform the step "calculate respectively according to the remaining cell voltages" Describes the deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within a certain period of time."

Item 17. A storage device in which a plurality of program codes are stored, characterized in that the program codes are adapted to be loaded and run by a processor to execute the power battery cells described in any one of Items 1 to 8. Battery short circuit monitoring method.

Solution 18. A control device, including a processor and a storage device. The storage device is adapted to store a plurality of program codes. It is characterized in that the program code is adapted to be loaded and run by the processor to execute solutions 1 to 1. The short circuit monitoring method of single cells in a power battery according to any one of 8.

One or more of the above technical solutions of the present invention have at least one or more of the following beneficial effects:

In the technical solution for implementing the present invention, through statistical analysis of cell voltages over a long period of time and with a large amount of data, it is concluded that the voltage of each cell of each cell relative to all cells within a long time range is The deviation of the average cell voltage of the battery. If the deviation of the cell voltage of all the cells is less than or equal to the preset deviation threshold, it means that no single cell is short-circuited. Based on the average cell voltage of all single cells, analyze the deviation of the cell voltage of each single cell from the average value and use this deviation to represent the voltage change state of each cell voltage, even if some cells The battery undergoes temporary ohmic polarization under the action of a large charging current or discharging current (for example: the cell voltage of some cells decreases and/or the cell voltage of some cells increases), but all cells The average cell voltage of the battery will also change accordingly. Therefore, as long as all cell voltages are still near the average cell voltage, it can be judged that no single cell short circuit has occurred. If the deviation of a part of the cell voltage of a single cell relative to the average cell voltage of all single cells is greater than the preset deviation threshold, it indicates that the single cell may be short-circuited. In this regard, the present invention further analyzes the deviation of the cell voltage over a longer period of time and with a larger amount of data, and concludes that within this longer time range, the cell voltage of this single cell deviates from the deviation of all cell voltages. The changing trend of the average value, and based on this changing trend, it is judged whether a single battery short circuit occurs. From the above analysis, it can be seen that the deviation of the cell voltage is only related to the average cell voltage of all single cells, and when analyzing whether a single cell short circuit occurs based on the deviation, only the comparison result of the deviation and the deviation threshold is considered As well as the changing trend of the deviation, no matter whether the single battery undergoes ohmic polarization, it will not affect the accuracy of the short-circuit monitoring results. Therefore, the present invention is not only suitable for small-current charging of power batteries and short-circuit monitoring of single batteries when the vehicle is stationary. , also suitable for high current charging of power batteries and single battery short circuit monitoring during vehicle driving.

Description of drawings

Specific embodiments of the present invention will be described below with reference to the accompanying drawings, in which:

Figure 1 is a schematic flowchart of the main steps of a short circuit monitoring method for single cells in a power battery according to one embodiment of the present invention;

Figure 2 is a schematic flowchart of the main steps of a short circuit monitoring method for single cells in a power battery according to another embodiment of the present invention;

Figure 3 is a schematic diagram of the main structure of a short circuit monitoring system for single cells in a power battery according to one embodiment of the present invention;

Figure 4 is a schematic diagram of the application scenario of the present invention;

List of reference signs:

11: Deviation calculation device; 12: Battery short circuit judgment device; 21: Electric vehicle; 22: Backend server.

Detailed ways

Some embodiments of the invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of the present invention.

In the description of the present invention, "module" and "processor" may include hardware, software, or a combination of both. A module can include hardware circuits, various suitable sensors, communication ports, and memory. It can also include software parts, such as program code, or it can be a combination of software and hardware. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. The processor has data and/or signal processing functions. The processor can be implemented in software, hardware, or a combination of both. Non-transitory computer-readable storage media include any suitable media that can store program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The term "A and/or B" means all possible combinations of A and B, such as just A, just B, or A and B. The terms "at least one A or B" or "at least one of A and B" have a similar meaning to "A and/or B" and may include just A, just B or A and B. The singular forms "a", "the" and "some" may also include the plural form.

Here we first explain some terms involved in the present invention.

Single battery refers to the basic battery unit that constitutes a power battery. Multiple single cells are connected in series and parallel to form a power battery.

Cell voltage refers to the voltage of a single battery.

The deviation degree of a cell voltage relative to the overall distribution of all cell voltages refers to the degree to which this cell voltage deviates from the mean value of all cell voltages. If the deviation of the cell voltage corresponding to a single cell is smaller, it means that the risk of short circuit of this single cell is lower.

The working current of the power battery refers to the working current of the power battery during the charging and discharging process (charging current or discharging current).

Since the resistance value of each single cell in the power battery is different, there will be a certain difference (voltage deviation) in the cell voltage of each single cell. For power batteries that do not have a single cell short circuit, these The voltage deviation is very small, that is, the single cells in the power battery have high voltage consistency. However, when a single cell short circuit occurs in a power battery, the voltage deviation between some of the cell voltages will be relatively large, resulting in low voltage consistency of the single cells. The existing short-circuit monitoring method of single cells in a power battery uses the voltage change pattern of the above-mentioned single cells to monitor whether a single cell short circuit occurs in the power battery, that is, to detect the voltage consistency of the single cells in the power battery. Determine whether a single cell short circuit occurs in the power battery based on the test results. However, when using a large current to charge a power battery, the large charging current will cause the single battery to undergo temporary ohmic polarization (the phenomenon that the electrode potential deviates from the equilibrium potential caused by the ohmic resistance of the battery), and ohmic polarization may It will reduce the voltage consistency of the single cells (for example: the single voltage of some single cells decreases and/or the single voltage of some single cells increases, resulting in a lower voltage consistency of the single cells), if it still Determining whether a single cell short circuit has occurred based on the voltage consistency test results will cause misjudgment. Therefore, this method is not suitable for detecting whether a single cell short circuit has occurred in the power battery when charging the power battery with a large current. Similarly, when the vehicle is driving, due to the complex and changeable driving conditions of the vehicle, the discharge current of the power battery may be relatively large, and the large discharge current will also cause short-term ohmic polarization of the single battery. Therefore, this kind of The method is also not suitable for detecting whether a single cell short circuit occurs in the power battery while the vehicle is driving.

In the embodiment of the present invention, the corresponding cell voltage of each cell in the power battery within a certain period of time is extracted, and the corresponding cell voltage of each cell during this period is calculated relative to all the received cell voltages. Deviation of the overall distribution, and based on these deviations, it is judged whether a single cell short circuit occurs in the power battery and an alarm message is output. An example: The battery management system in an electric vehicle detects the cell voltage of each cell in the power battery in real time, and sends the detected cell voltage to the backend server connected to the electric vehicle network. The backend server receives and stores each cell voltage. The corresponding cell voltage of each single cell in the power battery. After the background server determines that a single battery short circuit occurs in the power battery by performing the above operations, it outputs an alarm message to the electric vehicle to remind the electric vehicle user that there is a risk of single battery short circuit in the power battery and conduct timely maintenance.

The embodiment of the present invention performs statistical analysis on the cell voltages of a long time and a large amount of data, and obtains that the cell voltage of each cell relative to the cell voltages of all cells within a long time range If the deviation of the cell voltage of all single cells is less than or equal to the preset deviation threshold, it means that no single cell is short-circuited. Based on the average cell voltage of all single cells, analyze the deviation of the cell voltage of each single cell from the average value and use this deviation to represent the voltage change state of each cell voltage, even if some cells The battery undergoes temporary ohmic polarization under the action of a large charging current or discharging current (for example: the cell voltage of some cells decreases and/or the cell voltage of some cells increases), but all cells The average cell voltage of the battery will also change accordingly. Therefore, as long as all cell voltages are still near the average cell voltage, it can be judged that no single cell short circuit has occurred.

If the deviation of a part of the cell voltage of a single cell relative to the average cell voltage of all single cells is greater than the preset deviation threshold, it indicates that the single cell may be short-circuited. However, since the cell voltage of a single cell will fluctuate normally during the charging and discharging process, if it is determined that a short circuit has occurred in a single cell based only on the fact that the deviation of some cell voltages is greater than the preset deviation threshold, it may cause Therefore, the present invention further analyzes the deviation of the cell voltage over a longer period of time and with a larger amount of data, and concludes that the cell voltage of this single cell deviates from all cell voltages within this longer time range. The changing trend of the average value, and based on the changing trend, it is judged whether a single battery short circuit occurs. Specifically, the corresponding cell voltage of each single cell in the power battery can be extracted in time intervals, and the determination is first made based on the deviation of the cell voltage in the first time period (the deviation of the cell voltage in a shorter time range) Whether a single cell short circuit occurs in the power battery. If the deviation of a certain single cell voltage is greater than the preset deviation threshold, the deviation of the single cell voltage in the first period and the second period (in a longer time range) will be obtained at the same time. The deviation of the cell voltage), and then perform a linear regression calculation on all the deviations of this single cell within the above-mentioned long time range. If the slope value of the linear regression curve calculated by linear regression is less than zero (linear decreasing function), it means that the cell voltage of this single cell is gradually approaching the average cell voltage of all single cells, and the above part deviates from The cell voltage whose degree is greater than the deviation threshold is just the normal fluctuation of the single cell during the charging and discharging process. This single cell does not have a short circuit. If the slope of the linear regression curve is greater than zero (linear increasing function), it means that the cell voltage of this single cell is gradually moving away from the average cell voltage of all single cells. In this case, the slope value and the preset value can be used. The comparison result of the slope threshold is used to further determine whether a short circuit occurs in a single cell. The specific method is to test the power battery before short-circuit monitoring to obtain the slope of its corresponding linear regression curve when a single battery is short-circuited, and set the slope threshold according to the slope (the slope threshold is less than the slope and the slope threshold is greater than zero). ). During short circuit monitoring, after obtaining the slope corresponding to a single cell, the slope threshold is called and the slope is compared. If the slope corresponding to the single cell is greater than or equal to the slope threshold, it indicates that the single cell is in a short circuit state. If the voltage change state of the single cell is smaller than the slope threshold, it indicates that the single cell is still in a normal voltage change state and the single cell has not been short-circuited.

From the above analysis, it can be seen that the deviation of the cell voltage is only related to the average cell voltage of all single cells, and when analyzing whether a single cell short circuit occurs based on the deviation, only the comparison result of the deviation and the deviation threshold is considered As well as the changing trend of the deviation (the slope of the linear regression curve), regardless of whether the single battery undergoes ohmic polarization, it will not affect the accuracy of the short-circuit monitoring results. Therefore, the present invention is not only suitable for low-current charging of power batteries and when the vehicle is stationary. It is also suitable for high-current charging of power batteries and single battery short-circuit monitoring during vehicle driving.

Referring to FIG. 4, FIG. 4 is a schematic diagram of an application scenario according to an embodiment of the technical solution of the present invention. The electric vehicle 21 is provided with a communication device, a power battery, and a battery management system (Battery Management System, BMS) capable of detecting the battery parameters of the power battery (including but not limited to: the operating current of the power battery and the cell voltage of the single cell). The electric vehicle 21 establishes a communication connection with the backend server 22 through a communication device (including but not limited to: WIFI communication device and 4G communication device (communication device based on the fourth generation mobile communication and its technology)). The battery management system detects the cell voltage of each cell in the power battery in real time, and the electric vehicle 21 sends the detected cell voltage to the backend server 22 in real time through the communication device. The background server 22 performs data analysis on the received cell voltage, and when it is analyzed that a cell short circuit occurs in the power battery, it sends an alarm message to the electric vehicle 21 (for example: a cell short circuit occurs in the current power battery) to alert the electric vehicle. Drivers within 21 hours should promptly inspect the power battery.

Further, the backend server 22 can also communicate with the terminal of the user of the electric vehicle 21 (including but not limited to: mobile phone and tablet computer) and/or the service provider terminal of the electric vehicle (including but not limited to: computer equipment). After a single cell short circuit occurs in the power battery, alarm information is sent to the user's terminal and/or alarm information is sent to the service provider terminal of the electric vehicle (for example, based on the current identification code of the power battery (including but not limited to: the ID number of the power battery)). : The power battery with the ID number "Battery111" has a single cell short circuit) to remind the electric vehicle service provider to promptly repair the power battery.

Referring to FIG. 1 , FIG. 1 is a schematic flowchart of the main steps of a short circuit monitoring method for single cells in a power battery according to one embodiment of the present invention. As shown in Figure 1, the short circuit monitoring method of single cells in the power battery in the embodiment of the present invention mainly includes the following steps:

Step S101: Receive the cell voltage corresponding to each cell in the power battery.

In one embodiment, the cell voltage corresponding to each cell in the power battery detected and sent by a cell voltage detection device such as a battery management system can be directly received, or other cell voltages connected to the cell voltage detection device network can be received. The device sends the cell voltage of the power battery, and these devices can receive/store the cell voltage of the power battery detected by the cell voltage detection device. One example: directly receiving the corresponding cell voltage of each single cell in the power battery sent by the battery management system in the electric vehicle; another example: receiving the respective corresponding cell voltages of each single cell in the power battery sent by the on-board control device of the electric vehicle. Corresponding cell voltage, the vehicle-mounted control device is connected to the battery management system network and can receive/store the cell voltage of the power battery detected by the battery management system.

Step S102: Obtain the cell voltage corresponding to each cell in the power battery received within a certain period of time, and calculate the corresponding cell voltage of each cell voltage within the certain period of time relative to all cells received. Deviation from the overall distribution of voltage.

In the embodiment of the present invention, the deviation degree of a cell voltage relative to the overall distribution of all cell voltages refers to the degree to which this cell voltage deviates from the average value of all cell voltages.

In one embodiment, the method shown in the following formula (1) can be used to calculate the corresponding deviation of each cell voltage relative to the overall distribution of all received cell voltages within the certain period of time:

The meaning of each parameter in formula (1) is:

CellVolt _{i_j} is the cell voltage of the j-th cell in a power battery received at the i-th moment within the certain period of time, devi_i_j is the deviation corresponding to the cell voltage CellVolt _{i_j} , and AvgVolt _i is the cell voltage of the j-th cell in a power battery received at the i-th moment within the certain period of time. The average value of all cell voltages of this power battery received at the i-th time within the period, m is the total number of cell voltages of this power battery received within the certain period of time; StdVolt _i is the standard deviation of all cell voltages received at the i-th moment within the certain period of time,/>

The physical meaning of the deviation degree devi_i_j calculated by the above formula (1) in the embodiment of the present invention is based on the standard deviation StdVolt _i , how many standard deviations StdVolt _i does the cell voltage CellVolt _{i_j} have above the average AvgVolt _i , or How many standard deviations StdVolt _i are there below the mean AvgVolt _i ? This deviation devi_i_j can clearly indicate the degree to which the cell voltage CellVolt _{i_j} deviates from the overall distribution of all cell voltages.

In one embodiment, before separately calculating the deviation degree of each cell voltage relative to the overall distribution of all cell voltages received within the certain period of time, a cell voltage screening step may also be included. The body voltage screening step can remove non-real and effective cell voltages caused by data quality problems such as data transmission asynchronization, data loss or misalignment, thereby improving the accuracy of short circuit monitoring. This step specifically includes:

Step 1: Obtain each operating current of the powered battery received within the certain period of time. It should be noted that the “certain duration” in this embodiment is the same as the “certain duration” in the previous embodiment.

Step 2: Arrange the working currents in order of current reception time to obtain the working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current.

In this embodiment, a first-order difference calculation or a multi-order difference calculation can be performed on the working currents in the working current array to obtain the respective differences corresponding to each working current.

Step 3: Obtain the working current corresponding to the difference obtained in step 2 that is greater than the preset difference threshold and obtain the data reception time corresponding to the working current.

Step 4: Obtain the corresponding cell voltage of each cell received within a certain time range before and after the data reception time within the certain period of time and delete them, and then perform the step "respectively" based on the remaining cell voltages. Calculate the deviation degree of each cell voltage relative to the overall distribution of all cell voltages received within the certain period of time."

An example: Assume that the current time is 8:00 pm on January 1, 2020, and the preset battery short-circuit monitoring time is based on the current time as the starting point, 3 hours before the current time (January 1, 2020 5 pm), the default first time period is 2 hours, then the "preset first time period after the preset battery short circuit monitoring time" refers to 5 pm - 7 pm. Get the data received during this period. The working currents I ₁ , I ₂ ,...I ₁₂₀ of power battery A are arranged in the order of reception time to obtain the working current array {I ₁ , I ₂ ,...I ₁₂₀ }. For the working current Each operating current in the array is differentially calculated to obtain the corresponding difference {ΔI ₁ , ΔI ₂ ,...ΔI ₁₂₀ } for each operating current. Among them, the difference greater than the preset difference threshold is ΔI ₅₀ , and the difference ΔI ₅₀ corresponds to The data reception time of the operating current I ₅₀ is 5:50 pm. If the "certain time range before and after the data reception time" is within 10 minutes before and after 5:50 pm, obtain the cell voltages between 5:40 pm and 6 pm, delete these cell voltages, and then calculate the remaining The deviation of the cell voltage (the cell voltage received between 5:00 pm and 5:39 pm and between 6:01 pm and 7:00 pm).

Data quality problems such as out-of-synchronization of data transmission, data loss or misalignment will cause some cell voltages to be significantly different from other cell voltages received before and after them. These cell voltages cannot truly reflect the single cell voltage. If you use these cell voltages to determine whether a cell short circuit has occurred based on the voltage status at the corresponding reception time, misjudgment may occur, so these cell voltages need to be deleted. Considering that the difference can represent the change between discrete quantities, the embodiment of the present invention can obtain the change between all adjacent working currents by calculating the difference corresponding to each working current, and the current value can be determined based on the difference value Operating currents with abnormal fluctuations (the difference value is greater than the preset differential threshold). These operating currents have a relatively large current value difference compared with other operating currents received before and after them, and the cells received correspondingly at the receiving time of these operating currents The voltage is the above-mentioned cell voltage that needs to be deleted and cannot truly reflect the voltage status of the cell. Furthermore, in order to delete as much as possible all potential cell voltages that cannot truly reflect the voltage status of a single cell and improve the accuracy of short-circuit monitoring, all cell voltages received within a certain time range before and after the reception time of the above-mentioned working current can be Delete them all.

Furthermore, in one embodiment, after the cell voltage screening step, voltage filtering can be performed on the filtered cell voltage, and deviation calculation can be performed on the filtered cell voltage to further improve the accuracy of short circuit monitoring. In one embodiment, the cell voltage can be voltage filtered before the cell voltage screening step, and then the cell voltage after filtering can be screened by performing the cell voltage screening step, and the filtered cell voltage can be filtered. Deviation calculation further improves the accuracy of short circuit monitoring.

Step S103: Based on the corresponding deviation degree of each cell voltage, determine whether a cell short circuit occurs in the power battery. Specifically, if it is determined that a single cell short circuit has occurred in the power battery, go to step S104; if it is determined that a single cell short circuit has not occurred in the power battery, then go to step S105.

In one embodiment, the following steps can be followed to determine whether a single cell short circuit occurs in the power battery:

Step 1: Taking the preset battery short-circuit monitoring time as the starting point, obtain the corresponding first cell of each single cell in the power battery received within the preset first time period after the preset battery short-circuit monitoring time. voltage, respectively calculate the corresponding first deviation degree of each first cell voltage relative to the overall distribution of all first cell voltages.

An example: Assume that the current time is 8:00 pm on January 1, 2020, and the preset battery short-circuit monitoring time is based on the current time as the starting point, 3 hours before the current time (January 1, 2020 5 pm), the default first time period is 2 hours, then the "preset first time period after the preset battery short circuit monitoring time" refers to 5 pm - 7 pm. Get the data received during this period. The corresponding first cell voltage of each single cell in power battery A, and then calculate the voltage of each first cell in power battery A relative to all the received first cells according to the method shown in formula (1) The first degree of deviation from the overall distribution of voltage.

The preset first time period after the preset battery short-circuit monitoring time is a period of time before and relatively close to the current time. The cell voltage (first cell voltage) received during this period can approximately reflect Calculating and using the latest voltage status of the single cell (the first deviation) of these single cell voltages can more accurately determine whether a single cell short circuit occurs.

Step 2: Determine whether the first deviations corresponding to all the first cell voltages calculated in step 1 are less than or equal to the preset deviation threshold (the value range of the preset deviation threshold may be 1.5 to 10); If the first deviations corresponding to all first cell voltages are less than or equal to the preset deviation threshold, it is determined that no cell short circuit has occurred in the power battery. If the first deviation corresponding to a certain first cell voltage is greater than the preset deviation threshold, it can be determined that a cell short circuit occurs in the power battery.

In the embodiment of the present invention, by performing a long-term and large-amount deviation statistical analysis on the cell voltage of each cell, it can be obtained that the cell voltage of this cell deviates from the average value of all cell voltages within a period of time. If the deviation of all cell voltages during this period is less than or equal to the preset deviation threshold, it means that the cell voltage of this single cell has not been abnormal during this period and is in normal working condition; if During this period, if the deviation of some cell voltages is greater than the preset deviation threshold, it indicates that a short circuit may or may not have occurred in the single cell. Therefore, when the deviation of some cell voltages is greater than the preset deviation threshold, further analysis is needed to accurately determine whether a single cell short circuit has occurred.

Further, in one embodiment, when step 2 determines that the first deviation corresponding to a certain first cell voltage is greater than the preset deviation threshold, the following steps may also be followed to determine whether a single cell short circuit occurs in the power battery:

Step 21: Using the preset battery short-circuit monitoring time in the aforementioned embodiment as the time starting point, obtain the corresponding data of each single cell in the power battery received within the preset second time period before the preset battery short-circuit monitoring time. of the second cell voltage, respectively calculate the corresponding second deviation degree of each second cell voltage relative to the overall distribution of all second cell voltages. Wherein, the preset second time period is longer than the preset first time period in the aforementioned embodiment. An example: The preset second duration is 1-10 times the preset first duration.

An example: Assume that the current time is 8:00 pm on January 1, 2020, and the preset battery short-circuit monitoring time is based on the current time as the starting point, 3 hours before the current time (January 1, 2020 5 pm), the default second time period is 3 hours, then the "preset second time period before the preset battery short circuit monitoring time" refers to 2 pm - 5 pm. Get the data received during this period The corresponding second cell voltage of each single cell in power battery A, and then calculate the voltage of each second cell in power battery A relative to all second cells received according to the method shown in formula (1) The second degree of deviation from the overall distribution of voltage.

Step 22: Based on the first degree of deviation and the second degree of deviation, determine whether a single cell short circuit occurs in the power battery.

When it is impossible to determine whether a single cell short circuit occurs based on the deviation of the cell voltage in the first period, the embodiment of the present invention determines whether a single cell short circuit occurs based on a longer time range (a time range composed of the first time length and the second time length). The degree of deviation (the first degree of deviation and the second degree of deviation) of the internal cell voltage (the first cell voltage and the second cell voltage) can be used to evaluate the deviation of the cell voltage of a single cell over a longer period of time. The changing trend of the average value of the cell voltage can be further analyzed to determine whether a single cell short circuit occurs.

In one embodiment, the above step 22 may specifically include:

Step 221: Arrange the second deviation degree and the first deviation degree in order of the cell voltage receiving time to obtain a deviation degree array.

Step 222: Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain the linear regression curve equation and linear fitting degree. The size of the linear fitting degree can indicate the credibility of the linear regression calculation results. The greater the linear fitting degree, the greater the possibility of linearizing these deviations. Then the linear curve represented by the linear regression curve equation can It more truly reflects the changing trend of these deviations; the smaller the linear fitting degree, the smaller the possibility of linearizing these deviations, and the linear curve represented by the linear regression curve equation cannot reflect the trend more truly. The changing trends of these deviations. The linear regression calculation method used in this embodiment is a conventional linear regression method in this field, and will not be described again for simplicity of description.

An example: The first cell voltage of cell a in 120 power batteries A was received between 5:00 and 7:00 pm on January 1, 2020. These 120 cells were calculated according to the method shown in formula (1). The first degree of deviation corresponding to the first cell voltage; receiving the second cell voltage of cell a in 180 power battery A between 2:00 and 5:00 p.m., according to the method shown in formula (1) Calculate the second deviation degrees corresponding to the 180 second cell voltages; arrange the 180 second deviation degrees and the 120 first deviation degrees calculated above according to the order of the cell voltage reception time. Get the deviation array. Perform linear regression calculation on 300 deviation degrees in the deviation degree array, and then obtain the linear regression equation and linear fitting degree.

Step 223: Determine whether the linear fitting degree obtained in step 222 is greater than a preset first fitting degree threshold (the preset first fitting degree threshold may range from 0.3 to 1).

If the linear fitting degree is greater than the preset first fitting degree threshold, it indicates that the linear regression calculation result in step 222 has high credibility, and the linear curve represented by the linear regression curve equation can truly reflect these deviations. At this time, the slope value of the corresponding linear regression curve can be obtained according to the linear regression curve equation, and then it can be determined whether the slope value is greater than the preset slope threshold (the value range of the preset slope threshold can be 0.01 to 10 ); if yes, it is determined that a single cell short circuit has occurred in the power battery; if not, it is determined that a single cell short circuit has not occurred in the power battery.

If the linear fitting degree is less than or equal to the preset first fitting degree threshold, it indicates that the credibility of the linear regression calculation result in step 222 is low. In order to simplify the processing logic of short circuit monitoring and reduce the corresponding computing workload, When the linear fitting degree is less than or equal to the preset first fitting degree threshold, whether a single cell short circuit occurs in the power battery can also be determined based on the comparison between the slope value of the linear regression curve and the preset slope threshold.

From the foregoing analysis, it can be seen that since the deviation of the cell voltage during the first period of time is greater than the preset deviation threshold, the method of comparing the deviation of the cell voltage with the preset deviation threshold can no longer be used. Determine whether a single battery short circuit occurs. Considering that the deviations of all cell voltages are discrete quantities, the embodiment of the present invention performs linear regression calculations on the deviations of these discrete cell voltages to obtain a linear regression that can characterize the variation trend of the deviations of these cell voltages. Curve equation and linear fitting degree. Under the condition that the linear fitting degree is greater than the preset first fitting degree threshold, the slope value of the linear regression curve equation is obtained, and this slope value is used as a representation of the deviation change trend of these monomer voltages. Quantitative index, the larger the slope value indicates that the single cell voltage of this single cell deviates more and more from the average value of all single cell voltages during this period. If the slope value is greater than the corresponding value when the single cell is short-circuited. Slope value (the above-mentioned preset slope threshold), you can immediately determine that a short circuit fault has occurred in this single battery.

Furthermore, in this embodiment, when the linear fitting degree is less than or equal to the preset first fitting degree threshold, in order to more accurately determine whether a single cell short circuit occurs in the power battery, the following may be included after step 223 step:

Step 224: Perform polynomial fitting calculation on the deviation degrees in the deviation degree array obtained in step 221, and obtain a second-order polynomial fitting curve equation and a polynomial fitting degree. The second-order polynomial fitting curve equation refers to an equation in which the highest term in the polynomial fitting curve equation is quadratic. Similar to the function of the linear fitting degree, the size of the polynomial fitting degree can indicate the credibility of the polynomial fitting calculation results. For the sake of simplicity, we will not go into details here. In addition, the polynomial fitting calculation method used in this embodiment is a conventional polynomial fitting method in this field, and will not be described again for simplicity of description.

Step 225: Determine whether the polynomial fitting degree obtained in step 224 is greater than the preset second fitting degree threshold (the preset first fitting degree threshold can range from 0.3 to 1); if so, obtain the second order The coefficient corresponding to the 2nd order term in the polynomial fitting curve equation.

If the polynomial fitting degree is greater than the preset second fitting degree threshold, it indicates that the polynomial fitting calculation result in step 224 has high credibility, and the polynomial fitting curve can truly reflect the variation trend of the deviation degree. At this time, it can be judged whether the coefficient corresponding to the second-order term (the coefficient of the highest term in the second-order polynomial fitting curve equation) is greater than zero; if so, it is judged that a single cell short circuit has occurred in the power battery; if not, it is judged that a single cell short circuit has not occurred in the power battery. The battery is short-circuited.

If the polynomial fitting degree is less than or equal to the preset second fitting degree threshold, it indicates that the reliability of the polynomial fitting calculation result in step 224 is low. At the same time, it can be seen from the foregoing analysis that the linear regression calculation results of these deviation degrees The reliability of Battery short circuit.

When the linear curve represented by the linear regression curve equation cannot truly reflect the changing trend of these deviations, the embodiment of the present invention combines the linear regression calculation results and the polynomial calculation results for analysis to specifically determine the extent of these deviations. What kind of change trend is it in, and then analyze whether a single battery short circuit occurs in the power battery based on the judgment results, avoiding misjudgment of single battery short circuit caused when the linear fitting degree is low.

The method of this embodiment is described below with reference to FIG. 2 to first determine that the first deviation corresponding to the first cell voltage is greater than the preset deviation threshold, and then simultaneously determine the first deviation corresponding to the first deviation and the second deviation corresponding to the second cell voltage. Taking the deviation degree to determine whether a single cell short circuit occurs in a power battery as an example, further details will be given.

Step S201: Receive the cell voltage corresponding to each cell in the power battery sent by the battery management system in the electric vehicle.

Step S202: Taking the preset battery short-circuit monitoring time as the starting point, obtain the corresponding first cells of each single cell in the power battery received within the preset first time period after the preset battery short-circuit monitoring time. Voltage.

Step S203: Calculate the first deviation degree corresponding to each first cell voltage relative to the overall distribution of all first cell voltages.

Step S204: Determine whether the first deviations corresponding to all first cell voltages are less than or equal to a preset deviation threshold. Specifically, if all first deviation degrees are less than or equal to the preset deviation threshold, go to step S216; if there is a first deviation greater than the preset deviation threshold, go to step S205.

Step S205: Taking the preset battery short-circuit monitoring time as the time starting point, obtain the second cells corresponding to each single cell in the power battery received within the preset second time period before the preset battery short-circuit monitoring time. Voltage.

Step S206: Calculate the second deviation degree corresponding to each second cell voltage relative to the overall distribution of all second cell voltages.

Step S207: Arrange the second deviation degree and the first deviation in order of cell voltage reception time to obtain a deviation degree array.

Step S208: Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain a linear regression curve equation and a linear fitting degree.

Step S209: Determine whether the linear fitting degree is greater than the preset first fitting degree threshold; if so, go to step S210; if not, go to step S212.

Step S210: Obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation.

Step S211: Determine whether the slope value is greater than the preset slope threshold; if so, go to step S215; if not, go to step S216.

Step S212: Perform polynomial fitting calculation on the deviation degrees in the deviation degree array to obtain a second-order polynomial fitting curve equation and a polynomial fitting degree.

Step S213: Determine whether the polynomial fitting degree is greater than the preset second fitting degree threshold; if so, go to step S214; if not, go to step S216.

Step S214: Obtain the coefficient corresponding to the second-order term in the second-order polynomial fitting curve equation and determine whether the coefficient is greater than zero; if so, go to step S215; if not, go to step S216.

Step S215: A single battery short circuit occurs and alarm information is output.

Step S216: No single battery short circuit occurs and no alarm information is output.

It should be pointed out that although the various steps are described in a specific order in the above embodiments, those skilled in the art can understand that in order to achieve the effects of the present invention, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in other sequences, and these changes are within the scope of the present invention.

Referring to FIG. 3 , FIG. 3 is a schematic diagram of the main structure of a short-circuit monitoring system for single cells in a power battery according to one embodiment of the present invention. As shown in FIG. 3 , the short-circuit monitoring system of single cells in the power battery in the embodiment of the present invention mainly includes a deviation calculation device 11 and a battery short-circuit judgment device 12 . For the sake of simplicity, although the processor and memory are not shown in Figure 3, those skilled in the art can understand that the short circuit monitoring system for single cells in the power battery may be part of the processor and/or memory. For example, in some embodiments, one or more modules in the deviation calculation device 11 and the battery short circuit determination device 12 may be part of the processor. In some implementations, these modules may respectively correspond to a part of the electronic circuit in the processor that performs signal or data processing, or may correspond to relevant program codes stored in a computer-readable medium (such as a memory). In some embodiments, one or more of the deviation calculation device 11 and the battery short circuit determination device 12 may be combined into one module. In some embodiments, the deviation calculation device 11 may be configured to obtain the corresponding cell voltage of each cell in the power battery received within a certain period of time, and separately calculate the voltage of each cell within the certain period of time. The deviation of each corresponding voltage from the overall distribution of voltages received by all cells. The battery short circuit determination device 12 may be configured to determine whether a single cell short circuit occurs in the power battery based on the corresponding deviation of each cell voltage; if so, output an alarm message. In one embodiment, the description of the specific implementation of the function may refer to steps S101 to S104.

In one embodiment, the deviation calculation device 11 may include a first deviation calculation module. In this embodiment, the first deviation calculation module may be configured to perform the following operations:

Taking the preset battery short-circuit monitoring time as the starting point, obtain the corresponding first cell voltage of each single cell in the power battery received within the preset first time period after the preset battery short-circuit monitoring time. , respectively calculate the corresponding first deviation degree of each first cell voltage relative to the overall distribution of all first cell voltages. In one embodiment, the description of the specific implementation of the function can be found in step S103.

In one embodiment, the battery short circuit judgment device 12 may include a first short circuit judgment module. In this embodiment, the first short circuit judgment module may be configured to perform the following operations:

It is determined whether the first deviation degrees corresponding to all the first cell voltages are less than or equal to the preset deviation threshold value; if so, it is determined that no single cell short circuit has occurred in the power battery. In one embodiment, the description of the specific implementation of the function can be found in step S103.

In one embodiment, the deviation calculation device 11 may include a second deviation calculation module. In this embodiment, the battery short circuit determination device 12 may include a second short circuit determination module.

The second deviation calculation module may be configured to use the preset battery short-circuit monitoring time as a time starting point to obtain each power battery received within a preset second time period before the preset battery short-circuit monitoring time. For the second cell voltage corresponding to each single cell, the second deviation degree corresponding to each second cell voltage relative to the overall distribution of all second cell voltages is calculated respectively; wherein, the preset second time period is longer than the preset second cell voltage. Set the first duration. The second short-circuit determination module may be configured such that when the first short-circuit determination module determines that the first deviation corresponding to a certain first cell voltage is greater than the preset deviation threshold, based on the first deviation and the second deviation, Determine whether a single cell short circuit occurs in the power battery. In one embodiment, the description of the specific implementation of the function can be found in step S103.

Further, in one embodiment, the second short-circuit determination module may be configured to perform the following operations: arrange the second degree of deviation and the first degree of deviation in order of cell voltage reception time to obtain a deviation degree array; Perform linear regression calculation on the deviation in the deviation array to obtain the linear regression curve equation and linear fitting degree; determine whether the linear fitting degree is greater than the preset first fitting degree threshold; if so, obtain it according to the linear regression curve equation The slope value of the corresponding linear regression curve; determine whether the slope value is greater than the preset slope threshold; if so, it is determined that a single cell short circuit has occurred in the power battery. In one embodiment, the description of the specific implementation of the function can be found in step S103.

Further, in one embodiment, the second short-circuit judgment module is configured to perform the following operations: if the linear fitting degree is less than or equal to the preset first fitting degree threshold, perform polynomial fitting on the deviation degree in the deviation degree array. Calculate together to obtain the second-order polynomial fitting curve equation and polynomial fitting degree; determine whether the polynomial fitting degree is greater than the preset second fitting degree threshold; if so, obtain the corresponding second-order term in the second-order polynomial fitting curve equation coefficient; determine whether the coefficient corresponding to the second-order term is greater than zero; if so, it is determined that a single cell short circuit has occurred in the power battery; if not, it is determined that a single cell short circuit has not occurred in the power battery. In one embodiment, the description of the specific implementation of the function can be found in step S103.

In one embodiment, the deviation calculation device 11 may be configured to perform the method shown in formula (1) to calculate the deviation of each cell voltage relative to the overall distribution of all received cell voltages. In one embodiment, the description of the specific implementation of the function may be referred to step S102.

In one embodiment, the deviation calculation device 12 may be configured to perform the following operations:

Obtain each current data of the power battery received within the certain period of time;

Arrange the working currents in order of current reception time to obtain the working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current; obtain the difference greater than the preset difference threshold The working current and the data receiving time corresponding to the working current are obtained; the corresponding cell voltage of each single cell received within a certain time range before and after the data receiving time within a certain period of time is obtained and deleted, and then according to the remaining The cell voltage execution step "respectively calculates the corresponding deviation of each cell voltage within the certain period of time relative to the overall distribution of all received cell voltages." In one embodiment, the description of the specific implementation of the function may be referred to step S102.

The above-described short-circuit monitoring system for single cells in a power battery is used to implement the embodiment of the short-circuit monitoring method for single cells in a power battery shown in Figure 1. The technical principles, technical problems solved, and technical effects produced by the two are similar. , those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process and related instructions of the short-circuit monitoring system of single cells in power batteries can be referred to the short-circuit monitoring method of single cells in power batteries. The contents described in the embodiments will not be repeated here.

Based on the above method embodiment, the present invention also provides a storage device embodiment. In the storage device embodiment, the storage device stores multiple program codes, and the program codes are suitable to be loaded and run by the processor to perform the short circuit monitoring method of single cells in the power battery according to the above method embodiment. For ease of explanation, only the parts related to the embodiments of the present invention are shown. If specific technical details are not disclosed, please refer to the method part of the embodiments of the present invention.

Based on the above method embodiment, the present invention also provides a control device embodiment. In the control device embodiment, the device includes a processor and a storage device. The storage device stores a plurality of program codes. The program codes are suitable for being loaded and run by the processor to execute the single cells in the power battery of the above method embodiment. short circuit monitoring method. For ease of explanation, only the parts related to the embodiments of the present invention are shown. If specific technical details are not disclosed, please refer to the method part of the embodiments of the present invention.

Those skilled in the art can understand that the present invention can implement all or part of the process in the method of the above-mentioned embodiment, and can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable file. In the storage medium, when the computer program is executed by the processor, the steps of each of the above method embodiments can be implemented. Wherein, the computer program includes computer program code, which may be in the form of source code, object code, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, media, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal , telecommunications signals and software distribution media, etc. It should be noted that the content contained in the computer-readable medium can be appropriately added or deleted according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium Excludes electrical carrier signals and telecommunications signals.

Further, it should be understood that since the settings of each module are only to illustrate the functional units of the system of the present invention, the physical devices corresponding to these modules may be the processor itself, or a part of the software in the processor, a part of the hardware, or Part of the combination of software and hardware. Therefore, the number of individual modules in the figure is only illustrative.

Those skilled in the art can understand that various modules in the system can be split or merged adaptively. Such splitting or merging of specific modules will not cause the technical solutions to deviate from the principles of the present invention. Therefore, the technical solutions after splitting or merging will fall within the protection scope of the present invention.

The short circuit monitoring method of single cells in a power battery according to the embodiment of the present invention receives and stores the corresponding cell voltage of each single cell in each power battery sent by the battery management system in an electric vehicle, and extracts the power within a certain period of time. Calculate the corresponding cell voltage of each cell in the battery, and calculate the deviation of each cell voltage relative to the overall distribution of all cell voltages received during this period, and then make judgments based on these deviations Check whether the power battery has a single cell short circuit and output an alarm message. The embodiment of the present invention can analyze whether a short circuit occurs in a power battery based on the cell voltage of a large number of single cells for a long time under various conditions such as small current charging, large current charging, electric vehicle stationary, and electric vehicle running. Improving the accuracy of power battery short-circuit monitoring overcomes the problem in the existing technology that the power battery cannot be monitored for single cell short circuit during high-current charging and electric vehicle operation, resulting in reduced accuracy of monitoring results.

So far, the technical solution of the present invention has been described with reference to an embodiment shown in the drawings. However, those skilled in the art can easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and technical solutions after these modifications or substitutions will fall within the protection scope of the present invention.

Claims (14)

1. A short circuit monitoring method for single cells in a power battery, characterized in that the method includes: Taking the preset battery short-circuit monitoring time as the starting point, obtain the corresponding first cell voltage of each single cell in the power battery received within the preset first time period, and calculate the respective first cell voltages within the preset first time period. The first degree of deviation corresponding to each first cell voltage in the system is relative to the overall distribution of all received first cell voltages, and when the first degree of deviation corresponding to a certain first cell voltage is greater than the preset deviation When the threshold is set, the preset battery short-circuit monitoring time is used as the starting point, and the corresponding second data of each single cell in the power battery received within the preset second time period before the preset battery short-circuit monitoring time is obtained. Cell voltage, respectively calculate the corresponding second degree of deviation of each second cell voltage relative to the overall distribution of all second cell voltages received within the preset second time period, wherein the preset The second duration is greater than the preset first duration; Arrange the second degree of deviation and the first degree of deviation according to the order of the cell voltage receiving time to obtain a deviation degree array; Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain a linear regression curve equation; Obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation; Determine whether the slope value is greater than a preset slope threshold; If yes, it is determined that the power battery has a single cell short circuit, and an alarm message is output; if not, then it is determined that the power battery does not have a single cell short circuit; Wherein, the preset first time period after the preset battery short circuit monitoring time is a period of time before and relatively close to the current time. 2. The short circuit monitoring method of single cells in a power battery according to claim 1, characterized in that the method further includes: When the first deviations corresponding to all the first cell voltages are less than or equal to the preset deviation threshold, it is determined that no single cell short circuit has occurred in the power battery, and the first deviation and the The second degree of deviation is to determine whether a single cell circuit occurs in the power battery. 3. The method for short-circuit monitoring of single cells in a power battery according to claim 1, characterized in that the method further includes: Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain the linear fitting degree; Determine whether the linear fitting degree is greater than a preset first fitting degree threshold; if so, obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation. 4. The method for short-circuit monitoring of single cells in a power battery according to claim 3, further comprising: If the linear fitting degree is less than or equal to the preset first fitting degree threshold, polynomial fitting calculation is performed on the deviation degrees in the deviation degree array to obtain a second-order polynomial fitting curve equation and a polynomial fitting degree. ; Determine whether the polynomial fitting degree is greater than a preset second fitting degree threshold; If the polynomial fitting degree is greater than the preset second fitting degree threshold, then obtain the coefficient corresponding to the 2nd order term in the 2nd order polynomial fitting curve equation and determine whether the coefficient is greater than zero; if so, determine the The power battery has a single cell short circuit; if not, it is determined that the power battery does not have a single cell short circuit; If the polynomial fitting degree is less than or equal to the preset second fitting degree threshold, it is determined that a single cell short circuit has not occurred in the power battery. 5. The method for short-circuit monitoring of single cells in a power battery according to any one of claims 1 to 4, characterized in that the method further includes: The first deviation degree and the second deviation degree are calculated according to the method shown in the following formula: Wherein, the CekkVolt _{i_j} is the first cell voltage or the second cell voltage of the j-th cell in the power battery received at the i-th time within a certain period of time, and the devi_i_j is the cell voltage The first degree of deviation or the second degree of deviation corresponding to CellVolt _{i_j} . The AvgVolt _i is the average value of all the first cell voltages received at the i-th moment within the preset first time period or the mean value of all first cell voltages received at the preset second time period. The mean value of all the second cell voltages received at the i-th moment within the duration, and the StdVolt _i is the standard deviation of all the first cell voltages received at the i-th moment within the preset first duration or the The standard deviation of all second cell voltages received at the i-th moment within the second time period is preset. 6. The method for short-circuit monitoring of single cells in a power battery according to any one of claims 1 to 4, characterized in that, before obtaining the first degree of deviation and the second degree of deviation, the method further includes: Obtain each operating current of the power battery received within the preset first time period or the preset second time period; Arrange the working currents in order of current reception time to obtain a working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current; Obtain the working current whose difference is greater than the preset difference threshold and the data reception time corresponding to the working current; Obtain the first cell voltage or the second cell voltage corresponding to each cell received within a certain time range before and after the data reception time within the preset first time period or the preset second time period and perform Delete, and then obtain the first degree of deviation or the second degree of deviation according to the remaining first cell voltage or second cell voltage. 7. A short circuit monitoring system for single cells in a power battery, characterized in that the system includes: The deviation calculation device is configured to use the preset battery short-circuit monitoring time as the starting point of time to obtain the corresponding first cell voltage of each single cell in the power battery received within the preset first time period, respectively. Calculate the first deviation degree corresponding to each first cell voltage relative to the overall distribution of all received first cell voltages within the preset first time period, and when a certain first cell voltage corresponds to When the first deviation is greater than the preset deviation threshold, the preset battery short-circuit monitoring time is used as the starting point, and each power battery received within the preset second time period before the preset battery short-circuit monitoring time is obtained. The second cell voltages corresponding to each of the single cells are respectively calculated within the preset second time period. The second cell voltage corresponding to each second cell voltage is calculated relative to the overall distribution of all second cell voltages received. Deviation degree, wherein the preset second duration is greater than the preset first duration; A battery short-circuit judgment device configured to arrange the second degree of deviation and the first degree of deviation according to the order of cell voltage reception time to obtain a deviation degree array; Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain a linear regression curve equation; Obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation; Determine whether the slope value is greater than a preset slope threshold; If yes, it is determined that a single cell short circuit has occurred in the power battery, and an alarm message is output; if not, it is determined that a single cell short circuit has not occurred in the power battery. 8. The short-circuit monitoring system for single cells in a power battery according to claim 7, wherein the battery short-circuit determination device includes a first short-circuit determination module, and the first short-circuit determination module is configured to perform the following operations : When the first deviations corresponding to all first cell voltages are less than or equal to the preset deviation threshold, it is determined that no single cell short circuit occurs in the power battery. 9. The short-circuit monitoring system for single cells in a power battery according to claim 7, wherein the battery short-circuit determination device further includes a second short-circuit determination module, and the second short-circuit determination module is configured to perform the following operate: Perform linear regression calculation on the deviation degrees in the deviation degree array to obtain the linear fitting degree; Determine whether the linear fitting degree is greater than a preset first fitting degree threshold; if so, obtain the slope value of the corresponding linear regression curve according to the linear regression curve equation. 10. The short-circuit monitoring system for single cells in a power battery according to claim 9, wherein the second short-circuit determination module is configured to perform the following operations: If the linear fitting degree is less than or equal to the preset first fitting degree threshold, polynomial fitting calculation is performed on the deviation degrees in the deviation degree array to obtain a second-order polynomial fitting curve equation and a polynomial fitting degree. ; Determine whether the polynomial fitting degree is greater than a preset second fitting degree threshold; If the polynomial fitting degree is greater than the preset second fitting degree threshold, then obtain the coefficient corresponding to the 2nd order term in the 2nd order polynomial fitting curve equation and determine whether the coefficient is greater than zero; if so, determine the The power battery has a single cell short circuit; if not, it is determined that the power battery does not have a single cell short circuit; If the polynomial fitting degree is less than or equal to the preset second fitting degree threshold, it is determined that a single cell short circuit has not occurred in the power battery. 11. The short circuit monitoring system for single cells in a power battery according to any one of claims 7 to 10, characterized in that the deviation calculation device is configured to perform the following operations: The first deviation degree and the second deviation degree are calculated according to the method shown in the following formula: Wherein, the CellVolt _{i_j} is the first cell voltage or the second cell voltage of the j-th cell in the power battery received at the i-th moment within a certain period of time, and the devi_i_j is the cell voltage The first degree of deviation or the second degree of deviation corresponding to CellVolt _{i_j} . The AvgVolt _i is the average value of all the first single cell voltages received at the i-th moment within the preset first time period or the mean value of all the first single cell voltages received at the preset first time period. The mean value of all the second cell voltages received at the i-th time within the two time periods, and the StdVolt _i is the standard deviation of all the first cell voltages received at the i-th time within the preset first time period or at all times. The standard deviation of all second cell voltages received at the i-th moment within the preset second period of time. 12. The short circuit monitoring system for single cells in a power battery according to any one of claims 7 to 10, characterized in that the deviation calculation device is configured to perform the following operations: Obtain each operating current of the power battery received within the preset first time period or the preset second time period; Arrange the working currents in order of current reception time to obtain a working current array, perform differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current; Obtain the working current whose difference is greater than a preset difference threshold and obtain the data reception time corresponding to the working current; Obtain the first cell voltage or the second cell voltage corresponding to each cell received within a certain time range before and after the data reception time within the preset first time period or the preset second time period and perform Delete, and then obtain the first degree of deviation or the second degree of deviation according to the remaining first cell voltage or second cell voltage. 13. A storage device in which a plurality of program codes are stored, characterized in that the program codes are adapted to be loaded and run by a processor to execute the power battery cell according to any one of claims 1 to 6. Battery short circuit monitoring method. 14. A control device, comprising a processor and a storage device, the storage device being adapted to store a plurality of program codes, characterized in that the program codes are adapted to be loaded and run by the processor to execute claims 1 to 1 The short circuit monitoring method of single cells in a power battery according to any one of 6.