TWI761083B - Method, system and device for short circuit monitoring of single cell in power battery - Google Patents

Abstract

The invention relates to the technical field of battery short-circuit monitoring, and specifically provides a method, system and device for short-circuit monitoring of a single cell in a power battery, aiming to solve how to accurately monitor whether a single cell in a power battery is short-circuited. The present invention calculates the deviation of each cell voltage relative to the overall distribution of all cell voltages within a certain period of time, and then judges whether the cell is short-circuited according to these deviations. Long-term and large number of cell voltages in various situations such as current charging, electric vehicle static and electric vehicle operation are used to analyze whether the single cell is short-circuited, which improves the accuracy of the short-circuit monitoring of the single cell in the power battery and overcomes the existing technology. It is not possible to monitor whether the single battery is short-circuited during high-current charging and electric vehicle operation, which reduces the accuracy of the monitoring results.

Description

Method, system and device for short circuit monitoring of single cell in power battery

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

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

At present, the short-circuit monitoring method of the single battery in the power battery is mainly to use the battery management system in the electric vehicle to monitor whether the power battery is short-circuited when the power battery is charged with a small current and the electric vehicle is stationary. 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.

Correspondingly, there is a need in the art for a new power battery short circuit test solution to solve the above problems.

In order to overcome the above shortcomings, 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 a first aspect, a method for short-circuit monitoring of a single cell in a power battery is provided, the method comprising:

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

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

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

Wherein, the step of "judging whether the power battery has a single cell short circuit according to the deviation degree corresponding to each cell voltage" specifically includes: judging whether the first deviation degrees 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 occurs in the power battery.

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

When the first deviation degree corresponding to a certain first cell voltage is greater than the preset deviation degree threshold, the preset battery short-circuit monitoring time is taken as the time starting point, and the preset battery short-circuit monitoring time is obtained. The second cell voltage corresponding to each cell in the power battery received in the previous preset second time period is calculated, and the corresponding voltage of each second cell is calculated relative to all the second cells. the second degree of deviation of the overall distribution of the voltage;

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

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

Wherein, the step of "judging whether the power battery has a short-circuit of a single cell according to the first deviation degree and the second deviation degree" specifically includes:

Arrange the second deviation degree and the first deviation degree according to the cell voltage receiving time from first to last to obtain the deviation degree array;

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

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

It is judged whether the slope value is greater than a preset slope threshold; if so, it is judged that a single cell short circuit occurs in the power battery; if not, it is judged that no single cell short circuit occurs in the power battery.

The method further 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 the polynomial fit;

judging whether the polynomial fit is greater than a preset second fit threshold;

If the polynomial fitting degree is greater than the preset second fitting degree threshold, obtain the coefficient corresponding to the second-order term in the polynomial fitting curve equation and judge whether the coefficient is greater than zero; The single cell is short-circuited; if not, it is determined that the power battery has no single cell short-circuit;

If the polynomial fitting degree is less than or equal to a preset second fitting degree threshold, it is determined that the power battery has no single cell short circuit.

Wherein, the step of "respectively calculating the deviation of each cell voltage relative 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:

是在所述一定時長內第i時刻接收到的所述動力電池中第j個單體電池的單體電壓，所述devi_i_j是所述單體電壓

對應的偏離度，所述

是在所述一定時長內第i時刻接收到的所有單體電壓的均值，所述

是在所述一定時長內第i時刻接收到的所有單體電壓的標準差。said

is the cell voltage of the jth single cell in the power battery received at the ith time within the certain period of time, and the devi_i_j is the cell voltage

the corresponding degree of deviation, the

is the average value of all cell voltages received at the i-th time within the certain period of time, and the

is the standard deviation of all cell voltages received at the i-th time within the certain time period.

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

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

Arrange the working currents in the order of current receiving time from first to last to obtain an array of working currents, and perform differential calculation on the working currents in the array of working currents to obtain the corresponding difference of each working current;

Acquiring a working current whose difference is greater than a preset difference threshold and a data receiving time corresponding to the working current;

Acquire and delete the respective cell voltages of each cell received within a certain time range before and after the data receiving time within the certain period of time, and then perform the step "respectively calculate in The corresponding deviation of each cell voltage relative to the overall distribution of all cell voltages received within the certain period of time".

In a second aspect, a short circuit monitoring system for a single cell in a power battery is provided, the system comprising:

The deviation calculation device is configured to obtain the cell voltage corresponding to 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. Deviation relative to the overall distribution of all cell voltages received;

A battery short-circuit judging device is configured to judge whether the power battery has a single-battery short-circuit according to the corresponding deviation of each of the cell voltages; if so, output an alarm message.

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

Wherein, the battery short-circuit judging device includes a first short-circuit judging module, and the first short-circuit judging module is configured to perform the following operations: judging whether the first deviation degrees corresponding to all the first cell voltages are less than or equal to a preset value Deviation threshold; if yes, it is determined that there is no single cell short circuit 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 degree calculation module is configured to take the preset battery short-circuit monitoring time as a time starting point, and acquire the data received within a preset second time period before the preset battery short-circuit monitoring time. The second cell voltage corresponding to each cell in the power battery, and the second deviation degree corresponding to each second cell voltage relative to the overall distribution of all the second cell voltages is calculated respectively; Set the second duration to be greater than the preset first duration;

The second short-circuit judging module is configured to, when the first short-circuit judging module judges that the first deviation degree corresponding to a certain first cell voltage is greater than the preset deviation degree threshold, according to the first deviation The degree and the second deviation degree are used to determine whether the power battery is short-circuited with a single battery.

Wherein, it also includes that the second short-circuit judgment module is configured to perform the following operations:

Arrange the second deviation degree and the first deviation degree according to the cell voltage receiving time from first to last to obtain the deviation degree array;

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

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

It is judged whether the slope value is greater than a preset slope threshold; if so, it is judged that a single cell short circuit occurs in the power battery; if not, it is judged that no single cell short circuit occurs in the power battery.

Wherein, it also includes 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, perform polynomial fitting calculation on the deviation degree in the deviation degree array to obtain the second-order polynomial fitting curve equation and the polynomial fitting degree ;

judging whether the polynomial fit is greater than a preset second fit threshold;

If the polynomial fitting degree is greater than the preset second fitting degree threshold, obtain the coefficient corresponding to the second-order term in the second-order polynomial fitting curve equation and judge whether the coefficient is greater than zero; The power battery has a single cell short circuit; if not, it is determined that the power battery has no single cell short circuit;

If the polynomial fitting degree is less than or equal to a preset second fitting degree threshold, it is determined that the power battery has no single cell short circuit.

Wherein, it also 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:

是在所述一定時長內第i時刻接收到的所述動力電池中第j個單體電池的單體電壓，所述

是所述單體電壓

對應的偏離度，所述

是在所述一定時長內第i時刻接收到的所有單體電壓的均值，所述

是在所述一定時長內第i時刻接收到的所有單體電壓的標準差。Among them, the

is the cell voltage of the jth single cell in the power battery received at the ith time within the certain period of time, and the

is the cell voltage

the corresponding degree of deviation, the

is the average value of all cell voltages received at the i-th time within the certain period of time, and the

is the standard deviation of all cell voltages received at the i-th time within the certain time period.

Wherein, it also includes that the deviation calculation device is configured to perform the following operations:

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

Arrange the working currents in the order of current receiving time from first to last to obtain an array of working currents, and perform differential calculation on the working currents in the array of working currents to obtain the corresponding difference of each working current;

obtaining the working current whose difference is greater than a preset difference threshold and obtaining the data receiving time corresponding to the working current;

Acquire and delete the respective cell voltages of each cell received within a certain time range before and after the data receiving time within the certain period of time, and then perform the step "respectively calculate in The corresponding deviation of each cell voltage relative to the overall distribution of all cell voltages received within the 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 the short-circuit monitoring of a single cell in a power battery according to any one of the above method.

In a fourth aspect, a control device is provided, the control device comprising a processor and a storage device, the storage device being adapted to store a plurality of program codes, the program codes being adapted to be loaded and run by the processor to execute any one of the above The short-circuit monitoring method of the single cell in the power battery described in item.

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

In the implementation of the technical solution of the present invention, by performing statistical analysis on the cell voltage of a long time and a large amount of data, it is obtained that the voltage of each cell of each cell is relative to all cells within a long period of time. The degree of deviation of the mean value of the cell voltages of the batteries, if the degree of deviation of the cell voltages of all the single cells is less than or equal to the preset deviation degree threshold, it means that no single cell is short-circuited. Based on the average of the cell voltages of all cells, analyze the deviation of the cell voltage of each cell from the mean value and use the deviation to represent the voltage change state of each cell voltage, even if some cells The battery undergoes a brief ohmic polarization under the action of a large charge current or discharge 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, so as long as all cell voltages are still near the cell voltage average, it can be determined that there is no cell short circuit. If the deviation of a part of the cell voltages of a single cell from the average cell voltage of all the cells is greater than a preset deviation threshold, it indicates that the single cell may be short-circuited. In this regard, the present invention further analyzes the deviation degree of the cell voltage with a longer time period and a larger amount of data, and obtains that the cell voltage of this single cell deviates from all cell voltages within this longer time range. The change trend of the mean value, according to the change trend to determine whether a single cell short circuit occurs. It can be seen from the above analysis that the deviation degree of the cell voltage is only related to the average value of the cell voltage of all the cells, and only the comparison result of the deviation degree and the deviation degree threshold is considered when analyzing whether the single cell short circuit occurs according to the deviation degree. As well as the variation trend of the deviation, no matter whether the ohmic polarization occurs in the single battery, it will not affect the accuracy of the short-circuit monitoring result, so the present invention is not only suitable for the small-current charging of the power battery and the single-battery short-circuit monitoring when the vehicle is stationary , and is also suitable for high-current charging of power batteries and short-circuit monitoring of single cells during vehicle driving.

Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principle of the present invention, and are not intended to limit the protection 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 may include hardware circuits, various suitable sensors, communication ports, memory, and may also include software parts, such as program codes, or 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 may be implemented in software, hardware, or a combination of the two. Non-transitory computer-readable storage media include any suitable medium that can store program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, and the like. 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 can include just A, only B, or A and B. The singular terms "a," "the," and "an" may also include the plural.

Here, some terms involved in the present invention are explained first.

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

The cell voltage refers to the voltage of the cell.

The degree of deviation 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 indicates that the risk of short circuit in this single cell is lower.

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

Because the resistance value of each single cell in the power battery is not the same, there will be a certain difference (voltage deviation) in the single cell voltage of each single cell. For a power battery without a single cell short circuit, these The voltage deviation is small, that is, the single cells in the power battery have high voltage consistency. However, when the power battery is short-circuited by the single cells, the voltage deviation between the voltages of some cells will be relatively large, resulting in low voltage consistency of the single cells. The short-circuit monitoring method of the single cells in the power battery in the prior art is to use the above-mentioned voltage variation law of the single cells to monitor whether the single cell short circuit occurs in the power battery, that is, to detect the voltage consistency of the single cells in the power battery. The detection result determines whether the power battery has a short circuit of the single battery. However, when using a large current to charge the power battery, the large charging current will cause a short-term ohmic polarization of the single battery (the phenomenon that the electrode potential deviates from the equilibrium potential caused by the ohmic resistance of the battery), and the ohmic polarization may It will reduce the voltage consistency of the single cells (for example: the single cell voltage of some single cells is reduced and/or the single cell voltage of some single cells is increased, thereby reducing the voltage consistency of the single cells), if the Judging whether a single battery short circuit occurs based on the voltage consistency test result will cause misjudgment, so this method is not suitable for detecting whether a single battery short circuit occurs in the power battery when the power battery is charged with a large current. Similarly, during the driving process of the vehicle, 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, so this kind of The method is also not suitable for detecting whether the single battery short circuit occurs in the power battery during the driving process of the vehicle.

In the embodiment of the present invention, the cell voltage corresponding to each cell in the power battery within a certain period of time is extracted, and the corresponding cell voltage of each cell within this period of time is calculated relative to all cells received. The deviation of the overall distribution of the voltage, and according to these deviations, it is judged whether the power battery has a short circuit of the single battery and an alarm message is output. An example: The battery management system in the electric vehicle detects the cell voltage of each cell in the power battery in real time, and sends the detected cell voltage to the background server connected to the electric vehicle network, and the background server receives and stores each cell voltage. The cell voltage corresponding to each cell in the power battery. After judging that the power battery has a single cell short circuit by performing the above operations, the background server outputs an alarm message to the electric vehicle to remind the electric vehicle user that the power battery has the risk of a single cell short circuit, and repairs it in time.

In the embodiment of the present invention, by performing statistical analysis on the cell voltage of a long time and a large amount of data, it is obtained that the voltage of each cell of each cell is relative to the cell voltage 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 of the cell voltages of all cells, analyze the deviation of the cell voltage of each cell from the mean value and use the deviation to represent the voltage change state of each cell voltage, even if some cells The battery undergoes a brief ohmic polarization under the action of a large charge current or discharge 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, so as long as all cell voltages are still near the cell voltage average, it can be determined that there is no cell short circuit.

If the deviation of a part of the cell voltages of a single cell from the average cell voltage of all the cells is greater than a preset deviation threshold, it indicates that the single cell may be short-circuited. However, since the cell voltage of the single cell will fluctuate normally during the charging and discharging process, if it is determined that the single cell is short-circuited only based on the deviation of some cell voltages being greater than the preset deviation threshold, it may cause a short circuit. Therefore, the present invention further analyzes the deviation degree of the cell voltage with a longer time and a larger amount of data, and finds that the cell voltage of this single cell deviates from all cell voltages within this longer time range. The change trend of the mean value, according to the change trend to determine whether a single cell short circuit occurs. Specifically, the cell voltage corresponding to each cell in the power battery can be extracted in different time periods, and firstly judged according to the degree of deviation of the cell voltage in the first time period (the degree of deviation of the cell voltage in a short time range) Whether the power battery has a single cell short circuit, if the deviation of a certain cell voltage is greater than the preset deviation threshold, the deviation of the cell voltage in the first period and the second period (within a longer time range) is obtained at the same time. The deviation of the single cell voltage), and then perform a linear regression calculation on all the deviations of the single cell in the above-mentioned longer 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 value of the cell voltages of all cells, and the above part deviates The cell voltage whose degree is greater than the deviation threshold is only the normal fluctuation of the single cell during the charging and discharging process, and the single cell is not short-circuited. 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 value of the cell voltages of all cells. The comparison result of the slope threshold value can further judge whether the single battery is short-circuited. The specific method is to test the power battery before short-circuit monitoring to obtain the slope of the corresponding linear regression curve of a single battery when it 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, call the slope threshold and compare the slope. 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 corresponding slope of the single cell is less 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.

It can be seen from the above analysis that the deviation degree of the cell voltage is only related to the average value of the cell voltage of all the cells, and only the comparison result of the deviation degree and the deviation degree threshold is considered when analyzing whether the single cell short circuit occurs according to the deviation degree. As well as the variation trend of the deviation (the slope of the linear regression curve), no matter whether the ohmic polarization of the single battery occurs, it will not affect the accuracy of the short-circuit monitoring result, so the present invention is not only suitable for small current charging of the power battery and the vehicle is stationary It is also suitable for high-current charging of power batteries and short-circuit monitoring of single cells during vehicle driving.

Referring to FIG. 4 , FIG. 4 is a schematic diagram of an application scenario of an embodiment involved in 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 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 background server 22 through a communication device (including but not limited to: a WIFI communication device and a 4G communication device ((a 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 background server 22 in real time through the communication device. The backend server 22 analyzes the data of the received cell voltage, and when it is analyzed that the power battery has a cell short circuit, it sends an alarm message to the electric vehicle 21 (for example, the current power battery has a cell short circuit) to remind the electric vehicle. The driver in 21 repairs the power battery in time.

Further, the background server 22 may also be connected in communication with the terminal of the user of the electric vehicle 21 (including but not limited to: mobile phones and tablet computers) and/or the terminal of the service provider of the electric vehicle (including but not limited to: computer equipment). After the power battery has a single battery short circuit, send alarm information to the user's terminal and/or alarm information to the service provider terminal of the electric vehicle according to the current power battery identification code (including but not limited to: the ID number of the power battery) (for example, : The power battery whose ID number is "Battery111" has a single battery short circuit) to remind the service provider of the electric vehicle to repair the power battery in time.

Referring to FIG. 1 , FIG. 1 is a schematic flowchart of the main steps of a short circuit monitoring method for a single cell in a power battery according to an embodiment of the present invention. As shown in FIG. 1 , the short-circuit monitoring method for the single cell 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 voltage detection devices connected to the network can be received. The cell voltage of the power battery sent by the device, these devices can receive/store the cell voltage of the power battery detected by the cell voltage detection device. One example: directly receiving the cell voltage of each cell in the power battery sent by the battery management system in the electric vehicle; another example: receiving the respective cell voltage of each cell in the power battery sent by the on-board control Corresponding cell voltage, the vehicle 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 voltages corresponding to each cell in the power battery received within a certain period of time, and calculate the corresponding cell voltages of each cell voltage within the certain period of time relative to all the received cell voltages. The degree of deviation of the overall distribution of cell voltages.

In this embodiment of the present invention, the degree of deviation of one 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.

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

(1)

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

是在所述一定時長內第i時刻接收到的一個動力電池中第j個單體電池的單體電壓，

是單體電壓

對應的偏離度，

是在所述一定時長內第i時刻接收到的這個動力電池的所有單體電壓的均值，

是在所述一定時長內接收到的這個動力電池的單體電壓的總數；

是在所述一定時長內第i時刻接收到的所有單體電壓的標準差，

。

is the single cell voltage of the jth single cell in a power battery received at the ith time within the certain period of time,

is the cell voltage

the corresponding deviation,

is the average value of all cell voltages of the power battery received at the i-th time within the certain period of time,

is the total number of cell voltages of the power battery received within the certain period of time;

is the standard deviation of all cell voltages received at the i-th time within the certain period of time,

.

的物理意義是以標準差

為單位，單體電壓

在均值

之上有多少個標準差

，或是在均值

之下有多少個標準差

，該偏離度

能夠清楚表明單體電壓

偏離所有單體電壓總體分佈的程度。The deviation degree calculated by the above formula (1) in the embodiment of the present invention

The physical meaning of is the standard deviation

unit, cell voltage

at the mean

how many standard deviations above

, or at the mean

how many standard deviations below

, the deviation

Able to clearly indicate the cell voltage

The degree of deviation from the overall distribution of all cell voltages.

In one embodiment, before calculating the deviation of each cell voltage corresponding to the overall distribution of all cell voltages received within the certain period of time, a cell voltage screening step may be further included, by: The cell voltage screening step can remove unreal and effective cell voltages due to data quality problems such as data transmission asynchrony, 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 period of time" in this embodiment is the same as "the certain period of time" in the foregoing embodiments.

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

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

Step 3: Obtain a working current corresponding to a difference greater than a preset difference threshold among the differences obtained in step 2, and obtain a data receiving time corresponding to the working current.

Step 4: Obtain and delete the respective cell voltages of each cell received within a certain time range before and after the data receiving time within the certain period of time, and then perform the steps according to the remaining cell voltages" Calculate the corresponding deviation of each cell voltage relative to the overall distribution of all cell voltages received within the certain period of time".

，將這些工作電流按照接收時間由先至後的順序進行排列得到工作電流數組

，對工作電流數組中的每個工作電流進行差分計算，得到每個工作電流各自對應的差分

，其中，大於預設差分閾值的差分是

，該差分

對應的工作電流

的數據接收時間是下午5點50分。若“數據接收時間前後一定時間範圍”是下午5點50分的前後10分鐘內，則獲取下午5點40分至下午6點之間的單體電壓並刪除這些單體電壓，隨後計算剩下的單體電壓（下午5點至5點39分之間以及下午6點01分至下午7點之間接收到的單體電壓）的偏離度。An example: Assuming that the current time is 8:00 pm on January 1, 2020, the preset battery short-circuit monitoring time is based on the current time as the time starting point, 3 hours before the current time (January 01, 2020). 5:00 p.m.), the preset first time period is 2 hours, then “the preset first time period after the preset battery short-circuit monitoring time” refers to 5:00 p.m. to 7:00 p.m. to the operating current of the power battery A

, arrange these working currents in the order of receiving time from first to last to obtain the working current array

, perform differential calculation on each working current in the working current array, and obtain the corresponding difference of each working current

, where the difference greater than the preset difference threshold is

, the difference

Corresponding working current

The data reception time 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 6:00 pm and delete these cell voltages, and then calculate the remaining voltages. The deviation of the cell voltages (cell voltages received between 5:00 pm and 5:39 pm and between 6:01 pm and 7:00 pm).

Data quality problems such as asynchronous data transmission, data loss or misalignment will cause some cell voltages to have a large difference in voltage values compared with other cell voltages received before and after it, and these cell voltages cannot truly reflect the cell battery. In the voltage state at the corresponding receiving time, if these cell voltages are used to determine whether a single cell short circuit occurs, misjudgment may occur, and therefore these cell voltages need to be deleted. Considering that the difference can represent the variation between discrete quantities, in the embodiment of the present invention, by calculating the corresponding difference of each working current, the variation between all adjacent working currents can be obtained, and the current value can be determined according to the difference value. The working currents with abnormal fluctuations (the difference value is greater than the preset difference threshold), these working currents have a relatively large difference in current value compared with other working currents received before and after, and the cells received at the receiving time of these working currents correspond to The voltage is the above-mentioned cell voltage that cannot truly reflect the voltage state of the cell that needs to be deleted. Further, in order to delete all potential cell voltages that cannot truly reflect the voltage state of the cells as much as possible and improve the accuracy of short-circuit monitoring, all cell voltages received within a certain time range before and after the receiving time of the above working current can be calculated. are deleted.

Further, in one embodiment, after the cell voltage screening step, voltage filtering may be performed on the screened cell voltage, and deviation degree calculation may be performed on the cell voltage after the voltage filtering, so as to further improve the accuracy of short-circuit monitoring. In one embodiment, voltage filtering may be performed on the cell voltage before the cell voltage screening step, and then the cell voltage after voltage filtering may be screened by performing the cell voltage screening step, and the cell voltage after the screening may be screened. Deviation calculation to further improve the accuracy of short-circuit monitoring.

Step S103 : according to the corresponding deviation of each cell voltage, determine whether the power battery has a cell short circuit. Specifically, if it is determined that the power battery has a single cell short circuit, go to step S104; if it is determined that the power battery has no single cell short circuit, 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 time starting point, obtain the first cell corresponding to each single cell in the power battery received within the preset first time period after the preset battery short-circuit monitoring time. The bulk voltage is calculated, and the first deviation degree corresponding to each first cell voltage with respect to the overall distribution of all the first cell voltages is calculated respectively.

An example: Assuming that the current time is 8:00 pm on January 1, 2020, the preset battery short-circuit monitoring time is based on the current time as the time starting point, 3 hours before the current time (January 01, 2020). 5:00 p.m.), the preset first time period is 2 hours, then “the preset first time period after the preset battery short-circuit monitoring time” refers to 5:00 p.m. to 7:00 p.m. The corresponding first cell voltage of each single cell in power battery A is obtained, and then calculate the voltage of each first cell in power battery A relative to all received first cell voltages according to the method shown in formula (1). The first degree of deviation of the overall distribution of cell voltages.

The preset first time period after the preset battery short-circuit monitoring time is a period of time before the current time and relatively close to the current time, during which the cell voltage (first cell voltage) received during this time can be Approximately reflecting the latest voltage state of the single cells, and calculating and using the deviations (first deviations) of these cell voltages can more accurately determine whether a single cell short circuit occurs.

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

In the embodiment of the present invention, by performing statistical analysis on the deviation degree of the cell voltage of each single cell for a long time and a large amount of data, it can be concluded that the cell voltage of this single 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 indicates that the cell voltage of this single cell is not abnormal during this period and is in a normal working state; if During this period, if the deviation degree of some cell voltages is greater than the preset deviation degree threshold, it indicates that the single cell may or may not be short-circuited. Therefore, when the deviation degree of some cell voltages is greater than the preset deviation degree threshold, further analysis needs to be performed to accurately determine whether a single cell short circuit occurs.

Further, in one embodiment, when it is determined in step 2 that the first deviation degree corresponding to a certain first cell voltage is greater than the preset deviation degree threshold, it is also possible to determine whether the power battery has a single cell short circuit according to the following steps:

Step 21: Using the preset battery short-circuit monitoring time in the foregoing embodiment as the time starting point, obtain the respective battery cells in the power battery received within the preset second time period before the preset battery short-circuit monitoring time. For the corresponding second cell voltages, the corresponding second deviation degrees of each second cell voltage relative to the overall distribution of all the second cell voltages are calculated respectively. Wherein, the preset second duration is longer than the preset first duration in the foregoing embodiments. An example: the preset second duration is 1-10 times the preset first duration.

An example: Assuming that the current time is 8:00 pm on January 1, 2020, the preset battery short-circuit monitoring time is based on the current time as the time starting point, 3 hours before the current time (January 01, 2020). 5:00 pm), the preset second time period is 3 hours, then the “preset second time period before the preset battery short-circuit monitoring time” refers to 2:00 p.m. to 5:00 p.m. The corresponding second cell voltage of each single cell in power battery A is obtained, and then according to the method shown in formula (1), the voltage of each second cell in power battery A is calculated relative to all the received second cell voltages. The second degree of deviation of the overall distribution of cell voltages.

Step 22: According to the first deviation degree and the second deviation degree, determine whether the power battery is short-circuited with a single cell.

In the case where it is not possible to determine whether a single cell short circuit occurs according to the deviation of the cell voltage within the first period, the embodiment of the present invention uses a longer time range (the time composed of the first duration and the second duration) range) the deviation of the cell voltage (the first cell voltage and the second cell voltage) (the first deviation and the second deviation), which can evaluate the cell voltage of the cell in a longer time range Deviation from the variation trend of the mean value of all cell voltages, according to this variation trend, it can be further analyzed 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 according to the first-to-last order of the cell voltage receiving time to obtain a deviation degree array.

Step 222: Perform a linear regression calculation on the deviation degrees in the deviation degree array to obtain the linear regression curve equation and the linear fitting degree. The size of the linear fit can indicate the reliability of the linear regression calculation results. More realistically reflect the changing trend of these deviations; the smaller the linear fit, the less likely it is to linearize these deviations, and the linear curve represented by the linear regression curve equation cannot more truly reflect trends in these deviations. The linear regression calculation method adopted in this embodiment is a conventional linear regression method in the field, and for the sake of brevity, details are not repeated here.

An example: The first cell voltage of cell a in 120 power batteries A is received between 5:00 p.m. and 7:00 p.m. on January 1, 2020, and the 120 cell voltage is calculated according to the method shown in formula (1). The first deviation degree corresponding to the first cell voltage; the second cell voltage of cell a in 180 power batteries A is received between 2:00 pm and 5:00 pm, 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 120 first deviation degrees calculated above according to the order of cell voltage receiving time from first to last Get an array of deviations. The linear regression calculation is performed on the 300 deviation degrees in the deviation degree array, and then the linear regression equation and the linear fitting degree are obtained.

Step 223: Determine whether the linear fit obtained in step 222 is greater than a preset first fit threshold (the preset first fit 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 reliability, 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 determine 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 so, it is determined that the power battery has a single cell short circuit; if not, it is determined that the power battery has no single cell short circuit.

If the linear fit is less than or equal to the preset first fit threshold, it indicates that the reliability 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 computational workload, When the linear fitting degree is less than or equal to the preset first fitting degree threshold, it can also be judged whether the power battery is short-circuited according to the comparison result between the slope value of the linear regression curve and the preset slope threshold value.

It can be seen from the foregoing analysis that since the deviation of the cell voltage is greater than the preset deviation threshold in the first time period, the method of comparing the deviation of the cell voltage with the preset deviation threshold cannot be used. To determine whether a single battery short circuit occurs. Considering that the deviations of all the cell voltages are discrete quantities, the embodiment of the present invention performs linear regression calculation on the deviations of these discrete cell voltages, and obtains a linear regression that can characterize the variation trends of the deviations of these cell voltages. The curve equation and the linear fit degree, obtain the slope value of the linear regression curve equation under the condition that the linear fit degree is greater than the preset first degree of fit threshold, and use this slope value as the variation trend of the deviation of the voltages of these monomers. Quantitative index, the larger the slope value is, the greater the degree of deviation of the cell voltage of this single cell from the average value of all cell voltages during this period of time, if the slope value is greater than the corresponding one when the single cell is short-circuited. The slope value (the preset slope threshold above) can immediately determine that the single battery has a short-circuit fault.

Further, 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 the power battery is short-circuited, the following steps may be included after step 223 step:

Step 224: Perform a polynomial fitting calculation on the deviation degrees in the deviation degree array obtained in step 221, to obtain a second-order polynomial fitting curve equation and a polynomial fitting degree. The 2nd order polynomial fitting curve equation refers to an equation in which the highest term in the polynomial fitting curve equation is 2nd degree. Similar to the function of the linear fitting degree, the size of the polynomial fitting degree can indicate the reliability of the calculation result of the polynomial fitting. In addition, the polynomial fitting calculation method adopted in this embodiment is a conventional polynomial fitting method in the art, and for the sake of brevity of description, it will not be repeated.

Step 225: Determine whether the polynomial fit obtained in step 224 is greater than a preset second fit threshold (the preset first fit threshold can range from 0.3 to 1); if so, obtain the second-order fit The coefficient corresponding to the 2nd order term in the polynomial fit 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 reliability, 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 the power battery is short-circuited; if not, it is judged that the power battery has no single battery. The battery is shorted.

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, and it can be known from the foregoing analysis that the linear regression calculation results of these deviation degrees The reliability of the battery is also relatively low. This situation indicates that these deviations are in an irregular fluctuation state, indicating that the cell voltage of the single battery in the power battery may be in a normal fluctuation state, so it can be determined that the power battery does not have a single cell. The battery is shorted.

Under the circumstance that the linear curve represented by the linear regression curve equation cannot truly reflect the variation trend of these deviation degrees, the embodiment of the present invention combines the linear regression calculation result and the polynomial calculation result for analysis, and can specifically determine the extent of these deviation degrees. What kind of change trend is in, and then analyze whether the power battery has a single battery short circuit according to the judgment result, so as to avoid the misjudgment of the single battery short circuit caused by the low linear fit.

The method of this embodiment is described below with reference to FIG. 2 to first determine that the first deviation degree corresponding to the first cell voltage is greater than the preset deviation degree threshold, and then simultaneously according to the first deviation degree and the second cell voltage corresponding to the second cell voltage Take the deviation degree to judge whether the power battery has a short circuit of the single battery as an example, and further explain it in detail.

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 time starting point, obtain the first cell corresponding to each single cell in the power battery received within a preset first time period after the preset battery short-circuit monitoring time. body voltage.

Step S203 : Calculate the first deviation degree corresponding to each first cell voltage with respect to the overall distribution of all the first cell voltages, respectively.

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

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

Step S206 : Calculate the corresponding second deviation degree of each second cell voltage with respect to the overall distribution of all the second cell voltages, respectively.

Step S207 : arranging the second deviation degree and the first deviation according to the cell voltage receiving time from first to last to obtain a deviation degree array.

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

Step S209: Determine whether the linear fit is greater than the preset first fit 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 yes, 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 fit degree is greater than the preset second fit 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 an alarm message is output.

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

It should be pointed out that, although the steps in the above embodiments are described in a specific sequence, those skilled in the art can understand that in order to achieve the effect of the present invention, different steps do not necessarily need to be executed in such an order. It may be performed simultaneously (in parallel) or in other sequences, and these variations 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 a single cell in a power battery according to an embodiment of the present invention. As shown in FIG. 3 , in the embodiment of the present invention, the short circuit monitoring system of the single battery in the power battery mainly includes a deviation calculation device 11 and a battery short circuit judgment device 12 . For the sake of simplicity, although the processor and the memory are not shown in FIG. 3 , those skilled in the art will understand that the short circuit monitoring system for the single cells in the power battery may be a part of the processor and/or the 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 a part of the processor. In some embodiments, these modules may respectively correspond to a part of electronic circuits in the processor that perform signal or data processing, and may also correspond to related 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 judgment device 12 may be combined into one module. In some embodiments, the deviation calculation device 11 may be configured to obtain the cell voltage corresponding to each cell in the power battery received within a certain period of time, and to calculate each cell voltage within the certain period of time. The respective deviation of the cell voltages from the overall distribution of all cell voltages received. The battery short circuit judging device 12 may be configured to judge whether the power battery is short circuited according to the corresponding deviation of each cell voltage; if so, output an alarm message. In one embodiment, for the description of the specific implementation functions, reference may be made to the descriptions in steps S101 to S104.

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

Taking the preset battery short-circuit monitoring time as a time starting point, obtain the first cell corresponding to each single cell in the power battery received within a preset first time period after the preset battery short-circuit monitoring time voltage, respectively calculating the first deviation degree corresponding to each first cell voltage with respect to the overall distribution of all the first cell voltages. In one embodiment, for the description of the specific implementation function, reference may be made to the description in step S103.

In one embodiment, the battery short-circuit judgment device 12 may include a first short-circuit judgment module, and 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 all less than or equal to the preset deviation degree threshold; if so, it is determined that there is no single cell short circuit in the power battery. In one embodiment, for the description of the specific implementation function, reference may be made to the description in step S103.

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

The second deviation degree calculation module may be configured to take the preset battery short-circuit monitoring time as a time starting point, and acquire the 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 the second cell voltages is calculated respectively; wherein, the second time period is preset greater than the preset first duration. The second short-circuit judgment module may be configured to, when the first short-circuit judgment module judges that the first deviation degree corresponding to a certain first cell voltage is greater than the preset deviation degree threshold, according to the first deviation degree and the second deviation degree, Determine whether the power battery has a single battery short circuit. In one embodiment, for the description of the specific implementation function, reference may be made to the description in step S103.

Further, in one embodiment, the second short-circuit judgment module may be configured to perform the following operations: arranging the second deviation degree and the first deviation degree according to the cell voltage receiving time in a first-to-last order to obtain a deviation degree array; Perform linear regression calculation on the deviation degree in the deviation degree array to obtain the linear regression curve equation and the 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 value; if so, determine that the power battery has a single battery short circuit. In one embodiment, for the description of the specific implementation function, reference may be made to the description in step S103.

Further, in one embodiment, the second short-circuit judgment module is configured to perform the following operations: if the linear fit is less than or equal to a preset first fit threshold, perform polynomial fitting on the deviations in the deviation array Calculated together to obtain the second-order polynomial fitting curve equation and the 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 Determine whether the coefficient corresponding to the second-order term is greater than zero; if so, it is determined that the power battery has a single cell short circuit; if not, it is determined that the power battery has no single cell short circuit. In one embodiment, for the description of the specific implementation function, reference may be made to the description in step S103.

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

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

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

Arrange the working currents in the order of current receiving time from first to last to obtain the working current array, and perform differential calculation on the working currents in the working current array to obtain the corresponding difference of each working current; The working current and the data receiving time corresponding to the working current are obtained; the respective cell voltages corresponding to each single cell received within a certain time range before and after the data receiving time within the certain period of time are obtained and deleted, and then according to the remaining The cell voltage performs the step of "respectively calculating the degree of deviation of each cell voltage corresponding to the overall distribution of all cell voltages received within the certain period of time". In one embodiment, for the description of the specific implementation function, reference may be made to the description in step S102.

The above-mentioned short circuit monitoring system for a single cell in a power battery is used to implement the embodiment of the short circuit monitoring method for a single cell in a power battery shown in FIG. , 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 the single cell in the power battery can refer to the short-circuit monitoring method of the single cell in the power battery. The content described in the embodiment is not repeated here.

Based on the foregoing method embodiments, the present invention further provides a storage device embodiment. In the storage device embodiment, the storage device stores a plurality of program codes, and the program codes are adapted to be loaded and run by the processor to execute the method for short-circuit monitoring of single cells in a power battery according to the above method embodiments. For the convenience of description, only the parts related to the embodiments of the present invention are shown, and the 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 further provides a control device embodiment. In an embodiment of the control device, the device includes a processor and a storage device, the storage device stores a plurality of program codes, and the program codes are adapted to be loaded and run by the processor to execute the single battery in the power battery of the above method embodiments short-circuit monitoring method. For the convenience of description, only the parts related to the embodiments of the present invention are shown, and the 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 all or part of the process in the method for implementing the above-mentioned embodiment of the present invention can also be completed by instructing relevant hardware through a computer program, and the computer program can be stored in a computer-readable In the storage medium, when the computer program is executed by the processor, the steps of the foregoing method embodiments can be implemented. Wherein, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate form, and the like. The computer-readable medium may include: any entity or device capable of carrying the computer program code, medium, flash drive, flash drive, magnetic disk, optical disc, computer memory, read-only memory, random access memory, electrical carrier Signals, telecommunications signals, and software distribution media. It should be noted that the content contained in the computer-readable media may be appropriately increased or decreased 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 media Electric carrier signals and telecommunication signals are not included.

Further, it should be understood that since the setting of each module is only for describing the functional units of the system of the present invention, the physical device corresponding to these modules may be the processor itself, or a part of software in the processor, a part of hardware, or a part of software part of the combination with the hardware. Therefore, the numbers of the various modules in the figures are merely schematic.

Those skilled in the art can understand that each module in the system can be divided 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, and therefore, the technical solutions after splitting or combining will fall within the protection scope of the present invention.

The short-circuit monitoring method for a single cell in a power battery according to the embodiment of the present invention receives and stores the cell voltage corresponding to each cell in each power battery sent by the battery management system in the electric vehicle, and extracts the cell voltage within a certain period of time. The respective cell voltages of each cell in the power battery are calculated, and the corresponding deviations of each cell voltage from the overall distribution of all cell voltages received during this period are calculated separately, and then based on these deviations Determine whether the power battery has a single battery short circuit and output an alarm message. The embodiment of the present invention analyzes whether the power battery is short-circuited according to the cell voltages of a large number of cells for a long time under various conditions such as low-current charging, high-current charging, the stationary electric vehicle, and the running of the electric vehicle. The accuracy of the short circuit monitoring of the power battery overcomes the problem in the prior art that the power battery cannot be monitored for single battery short circuit during high current charging and when the electric vehicle is running, which reduces the accuracy of the monitoring results.

So far, the technical solutions of the present invention have been described with reference to one embodiment shown in the accompanying drawings, but 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 principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

11: Deviation calculation device 12: Battery short circuit judgment device 21: Electric Vehicles 22: Background server

Specific embodiments of the present invention are described below with reference to the accompanying drawings, in which: FIG. 1 is a schematic flow chart of main steps of a short circuit monitoring method for a single cell in a power battery according to an embodiment of the present invention. FIG. 2 is a schematic flow chart of main steps of a short circuit monitoring method for a single cell in a power battery according to another embodiment of the present invention. 3 is a schematic diagram of the main structure of a short circuit monitoring system for a single cell in a power battery according to an embodiment of the present invention. FIG. 4 is a schematic diagram of an application scenario of the present invention.

Claims (16)

A short-circuit monitoring method for a single cell in a power battery, comprising: acquiring the respective cell voltages corresponding to each single cell in the power battery received within a certain period of time, and separately calculating each cell voltage within the certain period of time. The degree of deviation of the respective body voltages relative to the overall distribution of all the received cell voltages; according to the respective deviations of the respective cell voltages, determine whether the power battery has a cell short circuit; if so, output the Alarm information; the step of "respectively calculating the deviation of each cell voltage relative to the overall distribution of all cell voltages received within the certain period of time" specifically includes: calculating all cell voltages according to the method shown in the following formula. Said deviation:

Wherein, the CellVolt _{i_j} is the cell voltage of the j-th single cell in the power battery received at the i-th time in the certain period of time, and the devi_i_j is the deviation corresponding to the cell voltage CellVolt _{i_j} degree, the AvgVolt _i is the average value of all cell voltages received at the i-th time within the certain time period, and the StdVolt _i is the average value of all cell voltages received at the i-th time within the certain time period standard deviation. The short-circuit monitoring method for single cells in a power battery according to claim 1, wherein "obtain the respective cell voltages corresponding to each single cell in the power battery received within a certain period of time, and calculate them separately in the The step of “deviation degree corresponding to each cell voltage relative 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 time starting point, and obtaining the The first cell voltage corresponding to each cell in the power battery is received within the preset first time period after the battery short-circuit monitoring time, and the corresponding first cell voltage is calculated respectively relative to the The first degree of deviation of the overall distribution of all first cell voltages. The short-circuit monitoring method for a single cell in a power battery according to claim 2, wherein the step of "judging whether a single cell short circuit occurs in the power battery according to the corresponding deviation of each cell voltage" is specific The method includes: judging whether the first deviation degrees corresponding to all the first cell voltages are all less than or equal to a preset deviation degree threshold; if so, judging that no single cell short circuit occurs in the power battery. The short-circuit monitoring method for a single cell in a power battery according to claim 3, wherein the step of "judging whether a single cell short circuit occurs in the power battery according to the corresponding deviation of each cell voltage" is further The method includes: when the first deviation degree corresponding to a certain first cell voltage is greater than the preset deviation degree threshold, taking the preset battery short circuit monitoring time as the time starting point, and obtaining the preset battery short circuit monitoring time The second cell voltage corresponding to each cell in the power battery is received within a preset second time period before the monitoring time, and the respective corresponding voltages of each second cell are calculated relative to all the second cell voltages. The second deviation degree of the overall distribution of the cell voltage; according to the first deviation degree and the second deviation degree, it is judged whether the power battery has a single cell short circuit; wherein, the preset second time period is greater than the preset second time period. Set the first duration. The short-circuit monitoring method for a single cell in a power battery according to claim 4, wherein the step of "judging whether a single cell short circuit occurs in the power battery according to the first deviation degree and the second deviation degree" specifically includes the following steps: : Arrange the second deviation degree and the first deviation degree in the order of the cell voltage receiving time from first to last to obtain the deviation degree array; perform linear regression calculation on the deviation degree in the deviation degree array to obtain the linear regression curve equation and linear fit; Determine whether the linear fit is greater than a preset first fit threshold; if so, obtain a corresponding slope value of the 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; if not, it is determined that the power battery does not have a single cell short circuit. The method for short-circuit monitoring of a single cell in a power battery according to claim 5, further comprising: if the linear fit is less than or equal to a preset first fit threshold, performing an analysis on the deviation degree array Perform polynomial fitting calculation on the deviation degree of , to obtain the second-order polynomial fitting curve equation and polynomial fitting degree; judge whether the polynomial fitting degree is greater than the preset second fitting degree threshold; if the polynomial fitting degree is greater than If the preset second fitting degree threshold is set, the coefficient corresponding to the second-order term in the second-order polynomial fitting curve equation is obtained, and it is judged whether the coefficient is greater than zero; ; if not, it is determined that the power battery has no single cell short circuit; if the polynomial fit is less than or equal to a preset second fit threshold, it is determined that the power battery has no single cell short circuit. The short-circuit monitoring method for a single cell in a power battery according to any one of claims 1 to 5, wherein in "respectively calculating the corresponding voltage of each cell within the certain period of time relative to the received Before the step of "deviation degree of the overall distribution of all cell voltages", the method for short-circuit monitoring of the single cells in the power battery further includes: acquiring each operating current of the power battery received within the certain period of time ; Arrange the working currents in the order of current receiving time to obtain the working current array, carry out differential calculation on the working currents in the working current array, and obtain the corresponding difference of each working current; Acquire the working current with the difference greater than the preset difference threshold and the data receiving time corresponding to the working current; obtain each single battery received within a certain time range before and after the data receiving time within the certain period of time. The corresponding cell voltage is deleted, and then according to the remaining cell voltages, the step "respectively calculate the deviation of each cell voltage corresponding to the overall distribution of all cell voltages received within the certain period of time. Spend". A short-circuit monitoring system for single cells in a power battery, comprising: a deviation calculation device, which is configured to obtain the respective cell voltages corresponding to each single cell in the power battery received within a certain period of time, and calculate respectively The deviation degree of each cell voltage corresponding to the overall distribution of all cell voltages received within the certain period of time; a battery short-circuit judging device, which is configured to correspond to each cell voltage according to the respective The deviation degree is determined to determine whether the power battery has a single battery short circuit; if so, output an alarm message; the deviation degree calculation device is configured to perform the following operations: Calculate the deviation degree according to the method shown in the following formula:

Wherein, the CellVolt _{i_j} is the cell voltage of the j-th single cell in the power battery received at the i-th time in the certain period of time, and the devi_i_j is the deviation corresponding to the cell voltage CellVolt _{i_j} degree, the AvgVolt _i is the average value of all cell voltages received at the i-th time within the certain time period, and the StdVolt _i is the average value of all cell voltages received at the i-th time within the certain time period standard deviation. The short-circuit monitoring system for a single cell in a power battery according to claim 8, 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 a preset battery short-circuit monitoring time as the starting point of time, obtain the corresponding time of each single cell in the power battery received within a preset first time period after the preset battery short-circuit monitoring time. For the first cell voltage, the first deviation degree corresponding to each first cell voltage with respect to the overall distribution of all the first cell voltages is calculated respectively. The short-circuit monitoring system for single cells in a power battery according to claim 9, wherein the battery short-circuit judging device includes a first short-circuit judging module, and the first short-circuit judging module is configured to perform the following operations: judging all Whether the first deviation degrees corresponding to the first cell voltages are all less than or equal to a preset deviation degree threshold; if so, it is determined that there is no single cell short circuit in the power battery. The short-circuit monitoring system for single cells in a power battery according to claim 10, 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 degree calculation module is configured to take the preset battery short-circuit monitoring time as a time starting point, and acquire the said data received within a preset second time period before the preset battery short-circuit monitoring time. The second cell voltage corresponding to each cell in the power battery, and the second deviation degree corresponding to each second cell voltage relative to the overall distribution of all the second cell voltages is calculated respectively; The second duration is set to be greater than the preset first duration; the second short-circuit judgment module is configured to be configured when the first short-circuit judgment module determines that the first deviation degree corresponding to a certain first cell voltage is greater than the predetermined first duration. When the preset deviation degree threshold is reached, according to the first deviation degree and the second deviation degree, it is judged whether the power battery has a single cell short circuit. The short-circuit monitoring system for single cells in a power battery according to claim 11, wherein the second short-circuit judging module is configured to perform the following operations: according to the cell voltage receiving time in a first-to-last order, the second deviation The degree of deviation is arranged with the first degree of deviation to obtain the degree of deviation array; Perform a linear regression calculation on the deviation degrees in the deviation degree array to obtain a linear regression curve equation and a linear fit; determine whether the linear fit is greater than a preset first fit threshold; if so, according to the Obtain the slope value of the corresponding linear regression curve using the linear regression curve equation; determine whether the slope value is greater than the preset slope threshold value; if so, determine that the power battery has a single battery short circuit; There is no single cell short circuit in the battery. The short-circuit monitoring system for a single cell in a power battery according to claim 12, wherein the second short-circuit judging module is configured to perform the following operations: if the linear fitting degree is less than or equal to a preset first fitting If the degree of fit threshold is set, perform polynomial fitting calculation on the degree of deviation in the degree of deviation array to obtain the second-order polynomial fitting curve equation and the degree of polynomial fitting; determine whether the degree of polynomial fitting is greater than a preset second fitting degree The degree of fit threshold; if the polynomial fitting degree is greater than the preset second fitting degree threshold, 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; , it is determined that the power battery has a single cell short circuit; if not, it is determined that the power battery has no single cell short circuit; if the polynomial fit is less than or equal to the preset second fit threshold, then It is determined that the power battery has no single cell short circuit. The short-circuit monitoring system for single cells in a power battery according to any one of claims 8 to 13, wherein the deviation calculation device is configured to perform the following operations: obtain the received data within the certain period of time Each working current of the power battery; arranging the working currents in the order of current receiving time from first to last to obtain a working current array, and performing differential calculation on the working currents in the working current array to obtain each working current The corresponding difference of the current; Obtain the working current whose difference is greater than the preset difference threshold and obtain the data receiving time corresponding to the working current; obtain each unit cell received within a certain time range before and after the data receiving time within the certain period of time The corresponding cell voltages are deleted, and then according to the remaining cell voltages, the step "respectively calculate the respective corresponding voltages of each cell within the certain period of time relative to the overall distribution of all cell voltages received". deviation". A storage device, wherein a plurality of program codes are stored, wherein the program codes are adapted to be loaded and run by a processor to perform the short circuit of a single cell in a power battery according to any one of claim items 1 to 7 monitoring method. 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 any of the request items 1 to 7 A method for monitoring short circuit of single cells in a power battery.

Images