CN110780210A

CN110780210A - Battery pack internal short circuit detection method and device and electric automobile

Info

Publication number: CN110780210A
Application number: CN201810854671.2A
Authority: CN
Inventors: 陈起武
Original assignee: Guangzhou Xiaopeng Motors Technology Co Ltd
Current assignee: Guangzhou Xiaopeng Motors Technology Co Ltd
Priority date: 2018-07-30
Filing date: 2018-07-30
Publication date: 2020-02-11
Anticipated expiration: 2038-07-30
Also published as: CN110780210B

Abstract

The invention discloses a method and a device for detecting short circuit in a battery pack and an electric automobile, and belongs to the technical field of automobile safety; determining an evaluation parameter of the battery pack corresponding to the standing time; and determining whether the internal short circuit exists in the battery pack according to the evaluation parameter of the battery pack corresponding to the standing time. The method and the device can directly utilize the evaluation parameters of the battery pack corresponding to the standing time to diagnose the internal short circuit of the battery pack, so that the short circuit fault in the battery pack can be responded in time.

Description

Battery pack internal short circuit detection method and device and electric automobile

Technical Field

The invention relates to the technical field of automobile safety, in particular to a method and a device for detecting short circuit in a battery pack and an electric automobile.

Background

With the law of reducing the emission of atmospheric pollutants in various countries, the use speed of global electric vehicles is increased, and China also vigorously promotes the development of electric vehicles. At present, lithium iron phosphate and ternary material batteries are mostly used as power batteries for electric automobiles in the market, the lithium power batteries can store large capacity and have active chemical characteristics, once a positive electrode and a negative electrode in the power batteries form a short circuit, the lithium power batteries can be directly conducted, and one characteristic of the short circuit in the batteries is that once a small place in the batteries starts to be short-circuited, the local temperature is higher and higher, and ignition and even explosion can occur.

The power battery of a common electric automobile is a lithium battery pack, the lithium battery pack is formed by connecting a plurality of battery modules in series, one battery module is formed by connecting a plurality of minimum module units in series, the minimum module unit is formed by connecting a plurality of battery cores in parallel, and one minimum module unit can be regarded as a single battery. Therefore, a power battery is a storage battery which is formed by connecting a plurality of single battery cells in parallel and then connecting the battery cells in series and has huge energy storage capacity, short circuits may exist in the battery cells due to the production process, materials, production environment, machines and the like of the battery cells and the battery pack in use, and the capacity of identifying possible micro short circuits in the battery pack is very important as a Battery Management System (BMS) which is a manager of the power battery.

Therefore, how to detect the short circuit phenomenon in the battery pack so as to give a warning before the complete short circuit, and to avoid the serious short circuit of the battery pack as much as possible is a primary consideration.

Disclosure of Invention

The embodiment of the invention provides a method and a device for detecting an internal short circuit of a battery pack and an electric vehicle, which are used for detecting the internal short circuit phenomenon in the battery pack.

In a first aspect, an embodiment of the present invention provides a method for detecting a short circuit in a battery pack, including:

after detecting that the electric automobile is powered on, determining standing time before the electric automobile is not powered on;

determining an evaluation parameter of the battery pack corresponding to the standing time;

and determining whether the internal short circuit exists in the battery pack according to the evaluation parameter of the battery pack corresponding to the standing time.

Therefore, whether the battery pack in the electric automobile has the internal short-circuit fault or not can be found in time, the response is made in time aiming at the internal short-circuit fault of the battery pack, and the property loss of the battery pack caused by the internal short-circuit fault is reduced.

In a second aspect, an embodiment of the present invention provides a device for detecting a short circuit in a battery pack, including:

the first determination unit is used for determining standing time before the electric automobile is not powered after the electric automobile is detected to be powered on;

the second determining unit is used for determining the evaluation parameters of the battery pack corresponding to the standing time;

and the first detection unit is used for determining whether the internal short circuit exists in the battery pack according to the evaluation parameter of the battery pack corresponding to the standing time.

In a third aspect, an embodiment of the present invention provides a computer-readable medium, in which computer-executable instructions are stored, where the computer-executable instructions are configured to execute the method for detecting a short circuit in a battery pack provided in the present application.

In a fourth aspect, an embodiment of the present invention provides an electronic device, including:

at least one processor; and

a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,

the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method for detecting short circuit in a battery pack provided herein.

The invention has the beneficial effects that:

according to the method and the device for detecting the short circuit in the battery pack and the electric automobile, provided by the embodiment of the invention, after the electrification of the electric automobile is detected, the standing time before the electrification of the electric automobile is determined; determining an evaluation parameter of the battery pack corresponding to the standing time; and determining whether the internal short circuit exists in the battery pack according to the evaluation parameter of the battery pack corresponding to the standing time. By adopting the method provided by the invention, whether the battery pack has the internal short circuit or not is determined by utilizing the evaluation parameters of the battery pack corresponding to the standing time, so that the short circuit fault in the battery pack can be found in time, the potential safety hazard of the battery pack is reduced, and the safety of the electric automobile is improved to a certain extent.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic flow chart of a method for detecting a short circuit in a battery pack according to an embodiment of the present invention;

fig. 2 is a schematic flow chart illustrating a process of determining whether there is an internal short circuit in a battery pack according to evaluation parameters corresponding to standing time according to an embodiment of the present invention;

fig. 3 is a second schematic flow chart of a method for detecting a short circuit in a battery pack according to an embodiment of the present invention;

fig. 4 is a schematic flowchart of a process for determining whether an evaluation parameter of a battery pack in a driving discharge mode satisfies an internal short-circuit fault detection condition in the driving discharge mode according to an embodiment of the present invention;

fig. 5 is a schematic flowchart of determining an evaluation parameter corresponding to a CC-CV charging mode according to an embodiment of the present invention;

fig. 6 is a schematic flowchart of a process for determining whether an evaluation parameter corresponding to a CC-CV charging mode satisfies an internal short-circuit fault detection condition of the CC-CV charging mode according to an embodiment of the present invention;

fig. 7 is one of the flow diagrams illustrating the process of determining whether the evaluation parameter of the battery pack in the vehicle-mounted charging mode satisfies the internal short circuit fault detection condition in the vehicle-mounted charging mode according to the embodiment of the present invention;

fig. 8 is a second schematic flowchart of a process for determining whether the evaluation parameter of the battery pack in the vehicle-mounted charging mode satisfies the internal short-circuit fault detection condition in the vehicle-mounted charging mode according to the embodiment of the present invention;

fig. 9 is a schematic flow chart illustrating a process of determining whether there is an internal short circuit in a battery pack according to the state of health SOH of the battery pack, the remaining capacity SOC of the battery pack, and the charging and discharging efficiency of the battery pack according to the embodiment of the present invention;

fig. 10 is a schematic flow chart illustrating a process of determining charging and discharging efficiency of a battery pack according to an embodiment of the present invention;

fig. 11 is a schematic flowchart illustrating a configuration of values of an internal short circuit diagnosis flag TRS according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a short circuit detection device in a battery pack according to an embodiment of the present invention;

fig. 13 is a schematic diagram of a hardware structure of a computing device for implementing a method for detecting a short circuit in a battery pack according to an embodiment of the present invention.

Detailed Description

The method and the device for detecting the internal short circuit of the battery pack and the electric vehicle are used for detecting the internal short circuit phenomenon in the battery pack.

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings of the specification, it being understood that the preferred embodiments described herein are merely for illustrating and explaining the present invention, and are not intended to limit the present invention, and that the embodiments and features of the embodiments in the present invention may be combined with each other without conflict.

To facilitate understanding of the invention, the present invention relates to technical terms in which:

1. the battery management system BMS, which is a link between a battery and a user, is mainly targeted for secondary batteries. In order to improve the utilization rate of the battery, prevent overcharge and overdischarge of the battery, and extend the service life of the battery, the BMS monitors the state of the battery. As battery management systems have evolved, other functions have also been added.

2. The power failure state means that the electric vehicle is in a power failure state before the electric vehicle is powered off, namely, the electric vehicle is in a normal flameout state, namely, the output voltage of a Vehicle Control Unit (VCU) is adjusted to be low voltage, and components such as a direct current-direct current inverter (DCDC), a motor and a Battery Management System (BMS) are in a low-voltage and high-voltage power failure state.

3. The internal short circuit refers to whether the single battery has an internal short circuit, and the single battery belongs to a smaller composition unit with respect to the battery pack, so that determining the internal short circuit phenomenon in the battery pack may also be referred to as determining a micro short circuit phenomenon in the battery pack.

4. The driving discharge mode means that the electric vehicle is in a driving state, and a battery pack in the electric vehicle is in a discharge state.

5. The first stage of Constant current and Constant Voltage charging is a Constant current charging stage, also called Constant current stage; when the voltage reaches a set constant voltage, switching to a second stage to carry out a constant voltage charging stage, also called a constant voltage stage, and gradually reducing the charging current; when the charging current reaches the current corresponding to the end of charging, the battery pack is fully charged, and the current corresponding to the end of charging may be, but is not limited to, 0.

6. The vehicle-mounted charging mode is that when the electric automobile is in power shortage, the vehicle-mounted charger charges a battery pack in the electric automobile.

7. The theoretical maximum temperature of the battery pack, i.e., the theoretical maximum temperature of the unit cells, means the theoretical maximum temperature that should not be exceeded by each unit cell in the battery pack.

8. The evaluation parameters are used for indicating the state of the battery pack, and the evaluation parameters are used for determining whether the internal short circuit exists in the battery pack, wherein the battery pack has different working modes, and the evaluation parameters corresponding to the different working modes and used for determining whether the internal short circuit exists in the battery pack in the working mode are different.

9. The standing time refers to the time from the last power-off of the electric vehicle to the next power-on of the electric vehicle, for example, when the time recorded when the electric vehicle was last powered off is 2018, 6, month, 2 and 12, and the time when the electric vehicle was last powered on is 2018, 6, month, 3 and 10, the standing time can be determined to be the time between 6, month, 2 and 12 and 6, month, 3 and 10, that is, 21 hours.

In the prior art, whether the battery pack has an internal short circuit condition is generally determined only by detecting the temperature and the voltage of the battery pack, and the problem of inaccurate detection results is caused by not considering the working mode of the battery pack and the standing time of the electric automobile.

In order to timely detect the internal short circuit phenomenon in the battery pack in the electric automobile so as to warn before the complete short circuit and avoid the occurrence of safety accidents caused by the serious short circuit of the battery pack as much as possible, the BMS system in the electric automobile executes the internal short circuit detection method of the battery pack provided by the invention to detect whether the internal short circuit exists in the battery pack and timely send out a warning when the internal short circuit is determined to exist. The method specifically comprises the following steps: the method comprises the steps that after a BMS detects that an electric automobile is powered on, the BMS determines standing time before the electric automobile is not powered on; determining an evaluation parameter of the battery pack corresponding to the standing time; and determining whether the internal short circuit exists in the battery pack according to the evaluation parameter of the battery pack corresponding to the standing time. Therefore, the BMS can detect whether the battery pack in the electric automobile has an internal short circuit phenomenon or not, so that when the internal short circuit phenomenon in the battery pack is determined, the BMS can report an early warning signal to inform an automobile owner in time, and serious safety accidents caused by more serious short circuit of the battery pack are avoided.

As shown in fig. 1, a schematic flow chart of a method for detecting a short circuit in a battery pack according to an embodiment of the present invention may include the following steps:

and S11, acquiring the standing time before the electric automobile is not powered on after the electric automobile is detected to be powered on.

In this step, since the electric vehicle is in an unused state for a long time, that is, the battery pack is in a standing state for a long time, when the driver drives the electric vehicle, the battery pack may have some potential safety hazards due to a long standing time because the electric vehicle is not powered on for a long time. In order to ensure the driving safety of the driver, after the electric automobile is powered on, the BMS determines the standing time before the electric automobile is not powered on.

And S12, determining the evaluation parameters of the battery pack corresponding to the standing time.

The evaluation parameters of the battery pack corresponding to the standing time in the invention can include, but are not limited to, at least one of the following: the minimum voltage, the average voltage, the number of the battery module where the single battery corresponding to the minimum voltage is located, the temperature and the average temperature of the single battery and the like of the single battery in the battery pack.

And S13, determining whether the battery pack has an internal short circuit according to the evaluation parameters of the battery pack corresponding to the standing time.

By implementing the processes shown in steps S11 to S13, whether an internal short circuit exists in the battery pack can be accurately determined, so that a response can be made in time to an internal short circuit fault in the battery pack, and the safety factor of the electric vehicle can be improved.

Preferably, before executing step S12, the following process may be further included:

and determining that the standing time is greater than a preset standing time threshold value.

In the step, when the BMS detects that the standing time before the electric automobile is not powered on is larger than a preset standing time threshold value, and the problem of potential safety hazard caused by long-time standing of the battery pack is avoided, the invention further provides that the standing time before the electric automobile is not powered on is determined, when the standing time is long enough, the invention can detect whether the internal short circuit phenomenon exists in the battery pack according to an internal short circuit detection process corresponding to the standing time, and if the standing time is not larger than the preset standing time threshold value, the internal short circuit phenomenon exists in the battery pack according to a working mode of the battery pack.

Specifically, the preset standing time threshold value in the present invention may be determined according to actual situations, and the present invention is not limited to the specific value.

Whether the internal short circuit phenomenon exists in the battery pack can be detected in time through the internal short circuit detection process corresponding to the standing time, and therefore potential safety hazards in the battery pack are avoided.

Preferably, step S13 may be executed with reference to the flow shown in fig. 2 based on the evaluation parameter of the battery pack corresponding to the standing time acquired in step S12, and may include the following steps:

and S21, determining the lowest voltage of each single battery in the battery pack and the serial number of the battery module where the single battery corresponding to the lowest voltage is located.

In this step, since the battery pack is obtained by connecting a plurality of battery modules in series, and each battery module is composed of a plurality of minimum module units, that is, a plurality of single batteries, when the battery pack has an internal short circuit, self-discharge is increased, and excessive voltage drop occurs in the battery pack during a long-time standing process; the invention provides a method for detecting the internal short circuit of a battery pack, which is characterized in that the internal short circuit of the battery pack is directly reflected on a single battery, and the voltage of the single battery is increased once the internal short circuit of the single battery exists, so that the lowest voltage of each single battery in the battery pack can be determined in order to detect whether the internal short circuit phenomenon exists in the battery pack, and the serial number of a battery module where the single battery corresponding to the lowest voltage is located can be determined in addition to determining the lowest voltage of the single battery in the battery pack in order to find out the battery module where the single battery with the internal short circuit phenomenon exists in the battery pack, so that maintenance personnel can conveniently maintain the battery module.

And S22, determining the average voltage of the single batteries in the battery pack.

In this step, in order to determine whether the single battery corresponding to the lowest voltage has an internal short circuit, the present invention further needs to determine the average voltage of the single batteries in the battery pack.

S23, judging whether the voltage difference value between the average voltage and the lowest voltage is larger than a preset first voltage difference value threshold value, if so, executing a step S24; otherwise, step S28 is executed.

Specifically, the minimum voltage and the average voltage in the single batteries in the battery pack are determined, so that the degree of deviation of the minimum voltage from the average voltage can be determined, if the deviation is large, that is, the voltage difference value in the step S23 is greater than the preset first voltage difference value threshold, it indicates that the single battery corresponding to the minimum voltage may have an internal short circuit phenomenon, and in order to accurately determine whether the single battery corresponding to the minimum voltage has an internal short circuit, the present invention provides to perform the following steps. When it is determined that the minimum voltage is less than the average voltage, that is, the voltage difference in step S23 is not greater than the preset first voltage difference threshold, it is determined that the internal short circuit phenomenon does not exist in the battery pack.

It should be noted that the first voltage difference threshold in the present invention may be determined empirically or actually, and the present invention does not limit the value thereof.

And S24, respectively determining the temperature of each single battery in the battery pack and the average temperature of the single batteries.

Specifically, if there is an internal short circuit in the battery pack, the battery pack discharges itself, which means that the resistor discharges the battery, and the energy of the battery is consumed in the form of heat loss, and the temperature is a direct indication of the heat loss. Therefore, in order to improve the accuracy of the determined internal short circuit result, the BMS may further determine the temperature and the average temperature of each unit cell in the battery pack.

For each of the first N single batteries with the respective temperatures, the processes shown in steps S25 to S28 are performed:

specifically, after the temperatures of the respective unit cells are determined based on step S24, the temperatures of all the unit cells are sorted in descending order, the temperatures of the first N unit cells are taken, and then the processes of steps S25 to S28 are performed for each of the unit cells corresponding to the first N temperatures respectively. In specific implementation, the value of N may be determined according to actual conditions, for example, N may be 3.

S25, judging whether the temperature difference between the temperature of the single battery and the average temperature is larger than a preset first temperature difference threshold value or not; if yes, go to step S26; otherwise, step S28 is executed.

In this step, since the temperature of the single battery in step S25 is relatively high, by determining the degree of the temperature deviation from the average temperature, if the deviation is relatively large, that is, the temperature of the single battery is relatively higher than the average temperature, it may be that the self-discharge of the single battery is relatively large, that is, it indicates that the single battery may have an internal short circuit phenomenon, and step S26 is performed to further determine whether the single battery has an internal short circuit. If the temperature deviation of the single battery is smaller than the average temperature, the single battery is indicated to have no internal short circuit phenomenon.

It should be noted that the first temperature difference threshold in the present invention may be determined empirically or actually, and the present invention does not limit the value thereof.

S26, determining whether the serial number of the battery module where the single battery is located is consistent with the serial number of the battery module where the single battery corresponding to the lowest voltage is located; if yes, go to step S27; otherwise, step S28 is executed.

In this step, when the determination result in the step S25 is yes, and when it is determined that the number of the battery module where the single battery is located is consistent with the number of the battery module where the single battery corresponding to the lowest voltage is located, it may be determined that there is a short circuit in the single battery, that is, step S27 is performed; otherwise, it is determined that there is no internal short circuit in the unit cell, i.e., step S28.

Specifically, when N is 3, the flows shown in steps S25 to S28 may be executed for the cells respectively corresponding to the highest temperature ranked first, the highest temperature ranked second, and the highest temperature ranked third, and then it is determined whether there is an internal short circuit in the three cells, that is, whether there is an internal short circuit in the battery pack.

And S27, determining that the single battery has an internal short circuit.

And S28, determining that no internal short circuit exists in the battery pack.

When the vehicle does not stand for a long time before being electrified, after the vehicle restarts, the BMS carries out data statistics according to self-checking, judges whether excessive voltage drop occurs in the single battery, judges whether unbalanced difference exists in the temperature of the corresponding battery module, and the like, and timely responds to the short circuit fault in the battery pack before the vehicle does not have high voltage, so that personal safety of the vehicle can be effectively prevented from being endangered, and property loss of the battery pack caused by internal short circuit fault is reduced. And by executing the internal short circuit detection process shown in the steps S21-S28, the internal short circuit condition existing in the battery pack when the battery pack is left for a long time before the electric automobile is not powered on can be accurately detected, and the safety of the electric automobile is improved.

Further, before it is determined that the electric vehicle is not powered on, when the standing time of the electric vehicle does not exceed a preset standing time threshold, it indicates that the standing time of the electric vehicle is short, and even if the detection result of the internal short circuit of the battery pack is detected by using the internal short circuit detection process corresponding to the standing time may be inaccurate, in order to improve the accuracy of the detection result of the internal short circuit of the battery pack and reduce the potential safety hazard of the electric vehicle, the present invention provides a process which can be implemented according to fig. 3, that is, a working mode of the battery pack in the electric vehicle is determined, and the internal short circuit in the battery pack is detected according to a driving discharge mode of the battery pack, and the internal short circuit detection process shown in fig. 3 may include the following steps:

and S31, determining the working mode of the battery pack in the electric automobile.

And S32, determining the evaluation parameters of the battery pack in the working mode.

S33, determining whether the evaluation parameters in the working mode meet the internal short circuit fault detection conditions in the working mode, and if so, executing a step S34; otherwise, step S35 is executed.

And S34, determining that the battery pack has an internal short circuit.

And S35, determining that the battery pack has no internal short circuit.

By executing the steps S31 to S35, when the battery pack operates in different modes, whether an internal short circuit exists in the current battery pack can be determined based on whether the evaluation parameter of the battery pack determined in the mode satisfies the internal short circuit detection condition in the mode, and based on the method, the internal short circuit condition of the battery pack can be determined in time, so that a response can be made in time for an internal short circuit fault in the battery pack, and the safety coefficient of the electric vehicle can be improved.

Based on the flow of fig. 3, the steps S32 and S33 are described in detail next:

specifically, the evaluation parameters of the battery packs corresponding to different working modes are different, that is, the internal short circuit detection processes executed in different working modes are different. Specifically, evaluation parameters corresponding to the respective operation modes may be preset, and then, after the operation mode of the battery pack is determined, the evaluation parameters corresponding to the determined operation mode may be determined from the preset evaluation parameters corresponding to the respective operation modes. Next, it is described in detail whether the evaluation parameters of the battery pack and the evaluation parameters of the battery pack in each operating mode satisfy the internal short circuit fault detection conditions in each operating mode when the operating mode is the driving discharging mode, the constant current CC-constant voltage CV charging mode, and the vehicle charging mode.

Preferably, when the working mode of the battery pack is determined to be the driving discharging mode based on step S31, the evaluation parameters of the battery pack in the driving discharging mode include a State of Charge (SOC), a lowest voltage, an average voltage, a highest temperature of the battery cell, an average temperature, a highest temperature, a theoretical highest temperature, and an internal resistance and an average internal resistance of the battery cell corresponding to the highest temperature; on this basis, step S33 may be executed according to the flow shown in fig. 4, that is, determining whether the evaluation parameter in the operation mode satisfies the internal short circuit fault detection condition in the operation mode may include the following steps:

s41, determining whether the SOC of the battery pack meets the residual capacity range corresponding to the driving discharge mode; if yes, go to step S42; otherwise, the flow ends.

In this step, the remaining capacity range corresponding to the driving discharge mode in the present invention is determined according to actual conditions, and may be [ 35%, 85% ], for example. In the driving discharge mode, the BMS may determine a current remaining capacity of a battery pack in the electric vehicle, and then when it is determined that the SOC of the current battery pack is within a range of [ 35%, 85% ], it is indicated in the range that an internal short result detected by using an internal short detection procedure of the driving discharge mode is more accurate. When it is determined that the SOC of the current battery pack is not in the range of [ 35%, 85% ], the flow ends.

And S42, determining the lowest voltage of the single batteries in the battery pack, the number of the battery module where the single battery corresponding to the lowest voltage is located and the average voltage of the single batteries in the battery pack.

When the battery pack in the electric automobile in the running discharge mode has an internal short circuit, the short circuit is represented as follows: therefore, in this step, in order to accurately determine whether an internal short circuit exists in the battery pack in the electric vehicle in the driving discharge mode, the invention provides that the lowest voltage in each battery cell in the battery pack, the number of the battery module where the battery cell corresponding to the lowest voltage is located, and the average voltage of the battery cells in the battery pack are determined.

S43, determining whether the voltage difference value between the average voltage and the lowest voltage is larger than a preset second voltage difference value threshold value; if yes, go to step S44; otherwise, step S46 is executed.

Specifically, the minimum voltage and the average voltage in the single batteries in the battery pack are determined, so that the degree of deviation of the minimum voltage from the average voltage can be determined, if the deviation is large, that is, the voltage difference value in the step S43 is greater than a preset second voltage difference value threshold, it indicates that the single battery corresponding to the minimum voltage may have an internal short circuit phenomenon, and in order to accurately determine whether the single battery corresponding to the minimum voltage has an internal short circuit, the present invention provides to perform the following steps. When it is determined that the minimum voltage is less than the average voltage, that is, the voltage difference in step S43 is not greater than the preset second voltage difference threshold, it is determined that the internal short circuit phenomenon does not exist in the battery pack.

It should be noted that the second voltage difference threshold in the present invention may be determined empirically or actually, and the present invention does not limit the value thereof.

And S44, determining the highest temperature of the single batteries in the battery pack, the serial number of the battery module where the single batteries are located corresponding to the highest temperature and the average temperature of the single batteries.

Since the battery pack itself generates heat due to the discharge, in order to accurately determine whether the single battery has an internal short circuit, the present invention further determines the maximum temperature of the single battery, the number of the battery module where the single battery corresponding to the maximum temperature is located, and the average temperature of the single battery when the determination result of step S43 is yes. And the higher the temperature is, the greater the probability that the single battery corresponding to the temperature has the internal short circuit, in order to accurately determine the internal short circuit in the battery pack, the BMS may sample the temperature of each single battery of the battery pack based on step S44 to determine the highest temperature and the average temperature in the battery pack, and then perform the subsequent steps.

S45, determining whether the temperature difference between the maximum temperature and the average temperature is larger than a preset second temperature difference threshold value; if yes, go to step S46; otherwise, step S413 is executed.

In this step, when the temperature difference between the maximum temperature and the average temperature is greater than the second temperature difference threshold, it indicates that the maximum temperature deviates from the average temperature to a greater extent, and further indicates that the single battery corresponding to the maximum temperature may have an internal short circuit. Otherwise, the difference between the maximum temperature and the average temperature is not large, and further the single battery corresponding to the maximum temperature does not have internal short circuit.

It should be noted that the second temperature difference threshold in the present invention may be determined empirically or actually, and the present invention does not limit the value thereof.

S46, determining whether the serial number of the battery module where the single battery corresponding to the lowest voltage is located is consistent with the serial number of the battery module where the single battery corresponding to the highest temperature is located; if yes, go to step S47; otherwise, step S413 is executed.

Specifically, when the determination result in step S45 is yes, it indicates that the single battery corresponding to the highest temperature may have an internal short circuit, and in order to further determine whether the single battery has an internal short circuit, the present invention proposes that, when it is determined that the number of the battery module in which the single battery corresponding to the lowest voltage is located is consistent with the number of the battery module in which the single battery corresponding to the highest temperature is located, it is determined that both the single battery corresponding to the lowest voltage and the single battery corresponding to the highest temperature exist in the battery module, and it may be determined that the battery module has an internal short circuit.

And S47, determining the theoretical highest temperature of the battery pack according to the initial temperature of the battery pack, the SOC and the SOH of the battery pack, the specific heat capacity coefficient of the battery pack and the discharge energy accumulated during the current electrification when the vehicle is electrified.

In order to further determine which single battery in the battery module has the internal short circuit, the influence of the previous discharge energy on the current temperature of the battery pack can be calculated according to the initial temperature at the time of power-on, the SOC, the State of Health (SOH) of the battery pack and the specific heat capacity coefficient of the battery pack, and the influence of the previous discharge energy on the current temperature of the battery pack can be represented by a theoretical maximum temperature, for example, the theoretical maximum temperature of the battery pack can be determined by the invention. Specifically, the theoretical temperature rise of the battery pack is determined according to the SOC and the SOH of the battery pack, the specific heat capacity coefficient of the battery pack and the discharge energy accumulated during the current electrification, and then the theoretical temperature rise and the initial temperature of the battery pack recorded during the electrification of the travelling crane are summed to obtain the theoretical maximum temperature.

S48, determining whether the highest temperature is larger than the theoretical highest temperature; if yes, go to step S49; otherwise, step S413 is executed.

In this step, when it is determined that the highest temperature in the battery pack determined in step S48 is higher than the theoretical highest temperature, since the temperature of the single battery should not be higher than the theoretical highest temperature under normal conditions, it can further indicate that the single battery corresponding to the highest temperature is more likely to have an internal short circuit.

And S49, determining the average internal resistance of the single batteries of the battery pack and the internal resistance of the single battery corresponding to the highest temperature.

In this step, in order to further determine whether there is an internal short circuit in the single battery corresponding to the highest temperature, the present invention further needs to determine the average internal resistance of the single battery and the internal resistance of the single battery corresponding to the highest temperature based on step S49.

S410, determining whether the internal resistance of the single battery corresponding to the highest temperature is smaller than the average internal resistance; if yes, go to step S411; otherwise, step S413 is executed.

When the internal short circuit exists in the battery pack, the internal resistance of the single battery cannot be increased, but the internal resistance of the single battery can be reduced, so that based on the principle, if the internal resistance of the single battery corresponding to the highest temperature is determined to be smaller than the average internal resistance, the internal short circuit fault detection condition under the driving discharge mode is determined to be met, and the internal short circuit of the single battery corresponding to the highest temperature can be accurately determined. Otherwise, determining that the internal short circuit fault detection condition under the driving discharge mode is not met, namely determining that the internal short circuit does not exist in the battery pack.

S411, determining whether the SOH of the battery pack is larger than a preset health condition threshold value, and if so, executing a step S412; otherwise, the flow ends.

Specifically, the health condition of the battery pack can also be determined, and it is only meaningful to detect the internal short circuit in the battery pack when the battery pack is healthy, that is, when the SOH is greater than the preset health condition threshold, because the entire battery pack may need to be replaced when the SOH is less than the preset health condition threshold, and since the battery packs all need to be replaced, it is not significant for the electric vehicle to detect the internal short circuit in the battery pack by using the detection method of fig. 4.

In fact, the step of determining whether the SOH of the battery pack is greater than the preset state of health threshold may also be executed after step S41, where it is set to be executed after the determination result of step S410 is yes, which may be determined according to actual conditions.

The health state threshold preset in the present invention may be, but not limited to, 80%, and may be specifically set according to actual conditions.

S412, determining that the internal short circuit fault detection condition under the driving discharge mode is met, and determining that the single battery corresponding to the highest temperature in the battery pack has an internal short circuit.

And S413, determining that the internal short circuit fault detection condition under the driving discharge mode is not met, namely determining that no internal short circuit exists in the battery pack.

Based on the flow shown in fig. 4, whether the battery pack has an internal short circuit or not in the driving discharge mode of the electric vehicle can be accurately determined, so that the potential safety hazard of the electric vehicle is reduced, and the safety of users in the electric vehicle in the driving process is ensured.

In summary, when the electric vehicle is in the driving discharge mode, when the SOH is greater than 80%, the SOH is greater than or equal to 35% and less than or equal to 85%, the voltage difference is greater than the second voltage difference threshold, the number of the battery module in which the single battery corresponding to the lowest voltage is located is the same as the number of the battery module in which the single battery corresponding to the highest temperature is located, the temperature difference is greater than the second temperature difference threshold, the highest temperature is higher than the theoretical highest temperature, and the internal resistance of the single battery corresponding to the highest temperature is smaller than the average internal resistance of the battery pack, it can be determined that the single battery corresponding to the highest temperature in the battery pack has.

Preferably, if it is determined based on step S31 that the operation mode of the battery pack is the constant-current CC-constant-voltage CV charging mode, the evaluation parameters of the battery pack in the CC-CV charging mode may include, but are not limited to: the remaining charge time, the first actual charge time, the second actual charge time, the first accumulated charge amount, the first charge amount to be charged, the second accumulated charge amount, the second charge amount to be charged, and the like of the battery pack.

Specifically, the step S32 may be executed according to the flow shown in fig. 5, that is, determining the evaluation parameter of the battery pack in the operating mode, and the step S32 may include the following steps:

and S51, estimating the remaining charging time of the battery pack according to the current SOC, SOH, capacity, current temperature, sampling current and the predicted charging curve of the battery pack.

Specifically, the charging mode of the power battery pack in the electric vehicle is a constant current-constant voltage charging mode, and when the BMS determines that the constant current-constant voltage charging mode currently adopted by the electric vehicle charges the battery pack therein, the BMS may estimate the current remaining charging time of the battery pack according to the current SOC and SOH of the battery pack, the capacity of the battery pack, the battery temperature, and a charging curve obtained by using the current and prediction. In the invention, the sampling electric quantity is a constant current because the current is in the constant current charging stage.

S52, determining whether the voltage of the currently collected battery pack reaches a set constant voltage; if yes, go to step S53; otherwise, execution continues with step S52.

In this step, in the constant current charging stage, the current voltage of the battery pack is continuously collected, and whether the collected voltage reaches the set constant voltage is determined, if so, it indicates that the battery pack will enter the constant voltage charging stage at the next time, and if not, the step S52 is continuously executed.

And S53, determining a first actual charging time and a first accumulated charge amount when the constant-current stage voltage reaches the set constant voltage, and predicting a first applied charging charge amount when the constant-current stage voltage reaches the set constant voltage.

When the collected voltage is determined to reach the set constant voltage, determining first actual charging time when the voltage in the constant current stage reaches the constant voltage, namely counting the first actual charging time in the constant current stage from the constant current charging stage when the electric vehicle is detected to be in the CC-CV charging mode to the time when the sampled voltage reaches the constant voltage, namely when the constant current charging stage is ended and enters the constant voltage charging stage, wherein the first actual charging time in the constant current stage can be recorded as T1.

Specifically, in order to improve the accuracy of the internal short detection result in the CC-CV charging mode, the first actual charging time T1 is determined, and simultaneously, the first accumulated charge amount is determined and the first applied charge amount is predicted, and for convenience of description, the first accumulated charge amount is denoted as Q1 and the first applied charge amount is denoted as Q0.

S54, reducing the charging current, and determining whether the reduced charging current reaches the current corresponding to the end of full charge; if yes, go to step S55; otherwise, execution continues with step S54.

Specifically, based on the CC-CV charging principle, after the electric vehicle enters the constant voltage charging phase, the charging current needs to be reduced, and then it is determined whether the reduced charging current reaches the current corresponding to the end of full charging, if the reduced charging current reaches the current corresponding to the end of full charging, the charging is ended, otherwise, the charging current needs to be reduced continuously, and step S54 is executed continuously. Preferably, the current corresponding to the end of the full charge in the present invention may be, but not limited to, 0, and the like, and may be specifically set according to the actual situation.

And S55, determining a second actual charging time and a second accumulated charge amount when the constant voltage stage current reaches the current corresponding to the charging end, and predicting a second chargeable charge amount when the constant voltage stage current reaches the current corresponding to the charging end.

In this step, when it is determined in step S54 that the reduced charging current reaches the current corresponding to the end of full charge, a second actual charging time, which is the second actual charging time from the start of the constant voltage phase to the end of full charge, is determined and may be denoted as T2.

Specifically, in order to improve the accuracy of the internal short detection result in the CC-CV charging mode, the second accumulated charge amount may be determined and the second charge amount to be charged predicted, along with the determination of the second actual charging time T2. For convenience of description, the second accumulated charge amount is denoted as Q3, and the second chargeable charge amount is denoted as Q2.

Based on this, the evaluation parameters of the battery pack in the CC-CV mode are determined as the remaining charge time, the first actual charge time, and the second actual charge time based on the steps S51 to S55.

Preferably, the residual charging time described above in the present invention includes a first residual charging time in the constant voltage phase and a second residual charging time in the constant current phase, where the first residual charging time is t1 and the second residual charging time is t 2.

Preferably, the evaluation parameters of the battery pack in the CC-CV charging mode provided by the present invention may further include, but are not limited to: the battery pack comprises a battery pack, a battery pack.

On this basis, step S33 may be executed according to the flowchart shown in fig. 6, that is, determining whether the evaluation parameter of the battery pack in the charging mode in the CC-CV operating mode satisfies the internal short circuit fault detection condition in the CC-CV charging mode, that is, determining whether an internal short circuit exists in the battery pack, and the method may include the following steps:

s61, determining a first product of the sum of the first and second charge-applying quantities and the micro-short circuit coefficient.

In this step, the sum of the first and second amounts of chargeable charge is denoted as Q0+ Q2, and if the micro-short-circuit coefficient in the present invention is denoted as β, the first product between the sum and the micro-short-circuit coefficient is denoted as (Q0+ Q2) × β.

S62, determining a sum of the first accumulated amount of charge and the second accumulated amount of charge.

In this step, the sum of the first accumulated charge amount and the second accumulated charge amount is taken as: q1+ Q3.

And S63, determining that the first product is smaller than the sum.

In this step, only when (Q0+ Q2) × β < (Q1+ Q3), it can indicate that the battery pack memory is internally short-circuited.

However, when it is determined that (Q0+ Q2) × β ≧ (Q1+ Q3), it is determined that there is no internal short circuit in the battery pack, and the flow ends.

S64, determining whether the first residual charging time is larger than the first actual charging time; if yes, go to step S65; otherwise, step S615 is executed.

Specifically, when the internal short circuit occurs in the battery pack, the charging time in the CC charging stage is shortened, and it may be determined whether the internal short circuit exists in the battery pack by determining whether the first remaining charging time is greater than the first actual charging time, that is, determining whether T1> T1 is established, and if yes, it indicates that the internal short circuit may exist in the battery pack.

S65, determining whether the second residual charging time is less than the second actual charging time, if yes, executing a step S66; otherwise, step S615 is executed.

Specifically, when the internal short circuit occurs in the battery pack, the charging time in the CV charging stage will become longer due to the power consumption of the internal short circuit, and it may be determined whether the internal short circuit exists in the battery pack by determining whether the second remaining charging time is smaller than the second actual charging time, that is, whether T2< T2 is established, if so, it is indicated that the internal short circuit may exist in the battery pack, and in order to improve the accuracy of the internal short circuit detection result, the subsequent steps are executed.

And S66, determining the sum of the first actual charging time and the second actual charging time, and determining the product of the residual charging time and the short-circuit fault coefficient in the battery pack.

In this step, the sum of the first actual charging time and the second actual charging time is recorded as T1+ T2, and the product of the remaining charging time and the short-circuit fault coefficient in the battery pack is recorded as T × α, where T is the remaining charging time and α is the short-circuit fault coefficient in the battery pack.

S67, determining whether the sum value is larger than the product; if yes, go to step S68; otherwise, step S615 is executed.

In this step, it is determined whether (T1+ T2) > T × α is true, and if it is determined that (T1+ T2) > T × α, step S68 is performed to further determine, otherwise, it is determined that there is no internal short circuit in the battery pack.

And S68, determining the highest temperature of the single batteries in the battery pack and the theoretical highest temperature of the battery pack.

Since the battery pack itself generates heat due to the discharge, in order to accurately determine whether the above-mentioned single battery has an internal short circuit, the present invention further determines the maximum temperature of the single battery and the theoretical maximum temperature of the battery pack when the determination result of step S67 is yes. Specifically, the charging energy of the battery pack from the CC-CV charging start to the charging end can be determined, the initial temperature of the battery pack and the specific heat capacity coefficient of the battery pack at the CC-CV charging start are recorded, the temperature rise of the battery pack is determined according to the charging energy and the specific heat capacity coefficient of the battery pack, and then the sum of the initial temperature and the temperature rise is determined to be the theoretical highest temperature of the battery pack.

S69, determining whether the maximum temperature is larger than the theoretical maximum temperature, if so, executing a step S610; otherwise, step S615 is executed.

In this step, when it is determined that the maximum temperature determined in step S68 is greater than the theoretical maximum temperature, it indicates that the cell corresponding to the maximum temperature may generate more heat due to the presence of the internal short circuit, resulting in a very high cell temperature.

S610, determining the internal resistance of the single battery corresponding to the highest temperature and the average internal resistance of the single batteries of the battery pack.

In order to further determine whether the single battery corresponding to the highest temperature has the internal short circuit, the internal resistance is also required to determine whether the battery pack has the internal short circuit.

S611, determining whether the internal resistance of the single battery corresponding to the highest temperature is smaller than the average internal resistance; if yes, go to step S612; otherwise, step S615 is executed.

Specifically, based on the principle that the internal resistance of the single battery with the internal short circuit in the battery pack memory is reduced, if it is determined in this step that the internal resistance of the single battery corresponding to the highest temperature is smaller than the average internal resistance determined in step S67, it is determined that the internal short circuit fault detection condition under the CC-CV charging mode is satisfied, and it can be accurately determined that the internal short circuit exists in the single battery corresponding to the highest temperature, otherwise it is determined that the internal short circuit fault detection condition under the CC-CV charging mode is not satisfied, that is, the single battery corresponding to the highest temperature does not have the internal short circuit, that is, it is determined that the internal short circuit does not.

S612, determining whether a first ratio between the first charge-applying amount and the first accumulated charge amount is greater than a first internal short-circuit ratio threshold, if so, performing step S613; otherwise, step S615 is executed.

In this step, only the following conditions are satisfied Under this condition, the battery pack has an internal short circuit, and SCQt1 is the first internal short circuit ratio threshold.

S613, determining whether a second ratio between the second accumulated charge amount and the second charge amount to be charged is greater than a second internal short-circuit ratio threshold, if so, performing step S614; otherwise, step S615 is executed.

In this step, only the following conditions are satisfied

Under this condition, an internal short circuit will be present in the battery pack, wherein SCQt2 is the second internal short circuit ratio threshold.

And S614, determining that the single battery corresponding to the highest temperature in the battery pack has an internal short circuit.

And S615, determining that no internal short circuit exists in the battery pack.

Based on the flow shown in fig. 6, the internal short circuit condition in the battery pack in the electric vehicle in the CC-CV charging mode can be accurately determined, and the safety of the electric vehicle is improved.

Preferably, after the step S611 shows yes, and before the step S612 is executed, the method further includes:

determining that the SOH of the battery pack is greater than a preset health threshold.

In this step, specifically, the health condition of the battery pack may be determined, and it is only meaningful to detect the internal short circuit in the battery pack when the battery pack is healthy, that is, the SOH is greater than the preset health condition threshold, because the entire battery pack may need to be replaced when the SOH is less than the preset health condition threshold, and since the battery packs all need to be replaced, the internal short circuit in the battery pack is detected by using the internal short circuit detection method in the CC-CV charging mode of fig. 5 and 6, which is not significant for the electric vehicle. In practice, the step of determining that the SOH of the battery pack is greater than the preset state of health threshold may be performed before step S61, which may be determined according to actual situations.

In summary, when the electric vehicle is in the CC-CV charging mode, when the SOH is greater than 80%, (T1+ T2) > T α, (Q0+ Q2) × β < (Q1+ Q3), and the maximum temperature is greater than the theoretical maximum temperature, and the internal resistance of the unit cell corresponding to the maximum temperature is smaller than the average internal resistance of the battery pack, it may be determined that there is an internal short circuit in the unit cell corresponding to the maximum temperature in the battery pack.

Preferably, if it is determined based on step S31 that the operating mode of the battery pack is the vehicle-mounted charging mode, the evaluation parameters of the battery pack in the vehicle-mounted charging mode include an internal short circuit diagnosis flag TRS, a state of health SOH of the battery pack, a remaining capacity SOC of the battery pack, and a charging and discharging efficiency of the battery pack; and step S33 may be executed according to the flow shown in fig. 7, that is, determining whether the evaluation parameter of the battery pack in the vehicle-mounted charging mode satisfies the internal short circuit fault detection condition in the vehicle-mounted charging mode, that is, detecting whether there is an internal short circuit in the battery pack according to the internal short circuit detection flow corresponding to the vehicle-mounted charging mode, and the method may include the following steps:

s71, judging whether the electric automobile is in the non-sleep mode at present, if so, executing a step S72; otherwise, the flow ends.

In this step, when it is determined that the electric vehicle is in the sleep mode, the internal short circuit detection process is directly ended without detecting whether the internal short circuit exists in the battery pack of the electric vehicle, and the internal short circuit detection process corresponding to the vehicle-mounted charging mode is executed only when it is determined that the electric vehicle is not in the sleep mode.

And S72, determining whether the evaluation parameters of the battery pack in the running discharging mode meet the internal short circuit fault detection conditions in the running discharging mode.

In this step, when it is detected that the electric vehicle is not in a sleep state, it is directly detected whether an internal short circuit exists in the battery pack according to an internal short circuit detection flow corresponding to the driving discharge mode shown in fig. 4.

S73, when it is determined that the internal short circuit fault detection condition under the running discharge mode is not met based on the running discharge mode, determining whether the value of an internal short circuit diagnosis mark TRS is a set value, and if so, executing a step S74; otherwise, step S75 is executed.

In this step, when the internal short circuit detection process corresponding to the driving discharge mode shown in fig. 4 is used to detect that there is no internal short circuit in the battery pack, in order to ensure the accuracy of the detection result, the present invention proposes to determine whether the value of the internal short circuit diagnosis flag TRS is a set value, if the set value can be 1, when it is determined that TRS is 1, step S74 is executed, otherwise, it is determined that there is no internal short circuit in the battery pack.

S74, determining whether the SOH of the battery pack, the SOC of the battery pack and the charge-discharge efficiency of the battery pack meet the internal short circuit fault detection condition in the vehicle-mounted charging mode.

When the internal short circuit of the battery pack internal memory occurs, the charging and discharging efficiency of the battery pack is far lower than the normal value of normal use due to the self-discharging of the battery pack under the condition of the internal short circuit. Therefore, in the step, in order to improve the accuracy of the internal short circuit detection result in the vehicle-mounted charging mode, the invention provides a method for determining whether the SOH, the SOC and the charging and discharging efficiency of the battery pack meet the internal short circuit fault detection condition in the vehicle-mounted charging mode so as to determine the internal short circuit condition of the battery pack. Whether an internal short circuit exists in the battery pack can be accurately determined based on the charging and discharging efficiency.

And S75, determining that no internal short circuit exists in the battery pack.

By executing the steps S71 to S75, whether an internal short circuit exists in the battery pack in the vehicle-mounted charging mode can be accurately determined, thereby improving the safety of the electric vehicle.

Preferably, on this basis, the process shown in fig. 8 is further included in the vehicle charging mode, and may include the following steps:

and S81, when the electric automobile is in a dormant state at present and is powered on again, determining the standing time of the electric automobile.

When it is determined at step S71 that the electric vehicle is in the sleep state, when the power is turned on again, the rest time of the electric vehicle may be determined.

S82, determining whether the standing time is larger than a set standing time threshold value, if so, executing a step S83; otherwise, the flow ends.

In the step, when the electric vehicle is in a dormant state, the BMS detects that the standing time of the electric vehicle is greater than a preset standing time threshold value, so as to avoid the potential safety hazard problem caused by long-time standing of the battery pack, the BMS determines whether an internal short circuit exists in the battery pack according to the evaluation parameters of the battery pack corresponding to the standing time, namely, detects whether the internal short circuit phenomenon exists in the battery pack according to an internal short circuit detection process corresponding to the standing time, and if the standing time is not greater than the preset standing time threshold value, the process is ended.

And S83, determining whether the battery pack has an internal short circuit according to the evaluation parameters of the battery pack corresponding to the standing time.

Specifically, the implementation of step S83 may refer to the related description of the internal short circuit detection process corresponding to the standing time shown in fig. 2, and is not repeated here.

And S84, when the internal short circuit of the battery pack does not exist, determining whether the evaluation parameters of the battery pack in the running discharging mode meet the internal short circuit fault detection conditions in the running discharging mode.

In this step, when it is detected that there is no internal short circuit in the battery pack based on step S83, in order to improve the accuracy of the internal short circuit detection result in the vehicle-mounted charging mode, the present invention provides a method for determining whether there is an internal short circuit in the battery pack according to a process of determining whether the evaluation parameter of the battery pack in the driving discharging mode shown in fig. 4 meets the internal short circuit fault detection condition in the driving discharging mode, that is, detecting the internal short circuit in the battery pack according to the internal short circuit detection process corresponding to the driving discharging mode, which specifically refers to the description in steps S41 to S413, and the repeated parts are not described in detail.

S85, when detecting that no internal short circuit exists in the battery pack according to the internal short circuit detection process corresponding to the driving discharge mode, determining whether the value of an internal short circuit diagnosis mark TRS is a set value, and if so, executing a step S86; otherwise, step S87 is executed.

In this step, when it is determined that there is no internal short circuit in the battery pack according to the descriptions in steps S41 to S413, in order to further improve the accuracy of the internal short circuit detection result, the value of the internal short circuit diagnosis flag is determined again here, and when it is determined that TRS is 1, step S87 is executed, otherwise, it is determined that there is no internal short circuit in the battery pack.

S86, determining whether the SOH of the battery pack, the SOC of the battery pack and the charge-discharge efficiency of the battery pack meet the internal short circuit fault detection condition in the vehicle-mounted charging mode.

In this step, the description of step S74 may be referred to, and the description will not be repeated here.

And S87, determining that no internal short circuit exists in the battery pack.

By executing the process shown in fig. 8, it is possible to accurately determine the internal short circuit condition of the battery pack when the vehicle is powered on again in the sleep mode.

Specifically, the step S74 or S86 may be executed according to the flow shown in fig. 9, and may include the following steps:

s91, determining whether the SOH is larger than a preset health condition threshold value, if so, executing a step S92; otherwise, the flow ends.

Specifically, the health condition of the battery pack is first determined, and it is only meaningful to detect the internal short circuit in the battery pack when the battery pack is healthy, that is, the SOH is greater than the preset health condition threshold, because the entire battery pack may need to be replaced when the SOH is less than the preset health condition threshold, and since the battery packs all need to be replaced, it is not significant for the electric vehicle to detect the internal short circuit in the battery pack by using the detection method of fig. 9.

S92, determining whether the SOC is not greater than a preset residual capacity threshold value; if yes, go to step S93; otherwise, the flow ends.

In this step, the preset remaining power threshold in the present invention may be, but is not limited to, 25%, that is, when it is determined that the current SOC of the battery pack is greater than 25%, step S103 is executed, otherwise, the process ends.

S93, determining whether the charge-discharge efficiency of the battery pack is not greater than a preset charge-discharge efficiency threshold, if so, executing a step S94; otherwise, step S95 is executed.

Specifically, when the internal short circuit occurs in the battery pack, the charging and discharging efficiency of the battery pack is far lower than the normal value in normal use due to the self-discharging of the battery pack under the condition of the internal short circuit. Therefore, whether the current charge-discharge efficiency of the battery pack is not greater than a preset charge-discharge efficiency threshold value or not can be judged, if not, the internal short circuit fault detection condition under the vehicle-mounted charging mode is determined to be met, namely, the battery pack is indicated to have low charge-discharge efficiency due to the internal short circuit, and then the battery pack is determined to have the internal short circuit, namely, the step S94 is executed; otherwise, it is determined that the internal short fault detection condition in the vehicle-mounted charging mode is not met, that is, it is determined that the internal short circuit does not exist in the battery pack, i.e., step S95.

Preferably, the charge and discharge efficiency of the battery pack in the step S93 may be determined according to the flowchart shown in fig. 10, including the steps of:

and S101, determining that the energy of the battery pack is lower than an early warning energy threshold value and then fully charging to the current accumulated use capacity.

Specifically, the determined current cumulative usage capacity may be denoted as Q4.

S102, determining the current theoretical residual capacity of the battery pack and the maximum available capacity at the current temperature according to the rated capacity of the battery pack, the temperature of the battery pack and the SOH.

Specifically, the rated capacity of the battery pack may be recorded as Q5, and then the current theoretical remaining capacity of the battery pack and the maximum available capacity at the current temperature may be calculated based on Q5, the temperature of the battery pack, and the SOH. For convenience of description, the current theoretical remaining capacity of the battery pack is herein denoted as Q6, and the maximum available capacity at the current temperature is denoted as Q7.

S103, determining the charging and discharging efficiency of the battery pack according to the current accumulated use capacity, the current theoretical residual capacity, the maximum available capacity and a preset internal short circuit diagnosis coefficient.

Specifically, the charge-discharge efficiency η of the battery pack may be determined according to the following formula:

in the above formula, λ is a preset internal short circuit diagnosis coefficient, which may be determined according to the state of health SOH of the battery and the usage environment of the battery.

And S94, determining that the internal short circuit fault detection condition in the vehicle-mounted charging mode is met.

When η is less than η 1, it is determined that the internal short circuit fault detection condition in the vehicle-mounted charging mode is met, that is, the internal short circuit in the battery pack is met, η 1 is a preset charging and discharging efficiency threshold, and the value is not limited by the invention according to the actual situation.

And S95, determining that the internal short circuit fault detection condition in the vehicle-mounted charging mode is not met.

When η is larger than or equal to η 1, it is determined that the internal short circuit fault detection condition in the vehicle-mounted charging mode is not met, that is, it is determined that no internal short circuit exists in the battery pack.

By executing the flow shown in fig. 7 or fig. 8 and fig. 9 to 10, it can be accurately determined whether there is a short circuit in the battery pack in the electric vehicle in the vehicle-mounted charging mode.

Preferably, the values of the internal short circuit diagnosis flag TRS in fig. 7 and 8 may be configured according to the flow shown in fig. 11, including the following steps:

and S111, determining the actual highest temperature of the battery pack when the vehicle-mounted charging reaches the full-charge condition.

In this step, the BMS may continuously detect whether the vehicle-mounted charging reaches a full charge condition, determine an actual maximum temperature of the battery pack if the vehicle-mounted charging reaches the full charge condition, and otherwise, continue the detection.

And S112, determining the theoretical highest temperature of the battery pack according to the initial temperature of the battery pack recorded before vehicle-mounted charging, the accumulated energy at the end of charging and the specific heat capacity coefficient of the battery.

In this step, the temperature rise of the battery pack from the start to the end of vehicle-mounted charging can be determined according to the accumulated energy and the specific heat capacity coefficient of the battery at the end of charging, and then the sum of the temperature rise and the initial temperature is determined as the theoretical maximum temperature of the battery pack.

And S113, configuring the value of the TRS according to the comparison result of the actual highest temperature and the theoretical highest temperature.

Specifically, when the actual maximum temperature is greater than the theoretical maximum temperature, setting TRS to 1; otherwise, TRS is set to 0. While saving the value of TRS.

Based on this, by implementing the flows shown in fig. 7 to 11, whether the battery pack has an internal short circuit in the vehicle charging mode can be accurately determined, and the safety of the electric vehicle is improved.

Preferably, the method for detecting an internal short circuit in a battery pack provided by the present invention further comprises:

and reporting an early warning signal when the internal short circuit of the battery pack is determined.

In this step, by implementing the flows shown in fig. 1 to 11, when a short circuit including a battery pack memory is determined, the driver can be alerted by reporting an early warning signal in time, so that the potential safety hazard of the electric vehicle is reduced to a certain extent.

Preferably, the method for detecting the short circuit in the battery pack provided by the invention can be applied to the production process of the battery pack, and has the following advantages: the quality of the produced battery pack finished product is ensured; defective products are prevented from being loaded into a vehicle and flowing into the market; the fault early warning avoids the occurrence of serious short circuit accident crisis personal safety, and can reduce the damage of the policy battery pack and the battery pack parts.

Preferably, the method for detecting the short circuit in the battery pack provided by the invention can also be applied to the use process of a vehicle, and has the following advantages: when the battery is not completely short-circuited seriously, a micro short-circuit fault alarm is given out; the driver can be ensured to stop in time when finding that the battery pack has a fault, thereby avoiding the personal safety of people inside and outside the vehicle from being endangered by serious short circuit of the battery; meanwhile, related battery maintainers can be informed to detect and maintain the battery in time.

The internal short circuit detection method provided by the invention improves the accuracy of the detection result, and the BMS diagnoses the internal short circuit of the battery pack by using different internal short circuit detection methods according to different scenes by combining the actual use scenes of the battery pack according to the external characteristics of the internal short circuit of the power battery pack of the electric automobile, and can effectively avoid the personal safety of the vehicle endangered by the internal short circuit fault of the battery pack and reduce the property loss of the battery pack caused by the internal short circuit fault by detecting whether the internal short circuit exists in the battery pack and responding to the short circuit fault in the battery pack in time; in addition, the internal short circuit fault detection conditions corresponding to different working modes are different, so that the method provided by the invention can be suitable for different application scenes of the battery pack.

Based on the same inventive concept, the embodiment of the invention also provides a device for detecting the short circuit in the battery pack, and as the principle of solving the problems of the device is similar to the method for detecting the short circuit in the battery pack, the implementation of the device can refer to the implementation of the method, and repeated parts are not described again.

As shown in fig. 12, a schematic structural diagram of a short circuit detection device in a battery pack according to an embodiment of the present invention includes:

the first determining unit 121 is configured to determine, after detecting that the electric vehicle is powered on, a standing time before the electric vehicle is not powered on;

a second determining unit 122, configured to determine an evaluation parameter of the battery pack corresponding to the standing time;

and the first detection unit 123 is configured to determine whether an internal short circuit exists in the battery pack according to the evaluation parameter of the battery pack corresponding to the standing time.

In one embodiment, the device for detecting a short circuit in a battery pack according to the present invention further includes:

a third determining unit 124, configured to determine that the standing time is greater than a preset standing time threshold before the second determining unit 122 determines the evaluation parameter of the battery pack corresponding to the standing time.

Preferably, the evaluation parameter of the battery pack corresponding to the standing time at least includes one of the following items: the minimum voltage, the average voltage and the number of the battery module where the single battery corresponding to the minimum voltage is located, the temperature and the average temperature of the single battery in the battery pack.

Further, the first detecting unit 123 is specifically configured to determine the lowest voltage of the single batteries in the battery pack and the number of the battery module where the single battery corresponding to the lowest voltage is located; determining an average voltage of the individual cells in the battery pack; when the voltage difference value between the average voltage and the lowest voltage is larger than a preset first voltage difference value threshold value, respectively determining the temperature of each single battery in the battery pack and the average temperature of the single batteries; for each of the first N single batteries with the respective temperatures, performing the following processes: when the temperature difference between the temperature of the single battery and the average temperature is larger than a preset first temperature difference threshold value, determining whether the number of the battery module where the single battery is located is consistent with the number of the battery module where the single battery corresponding to the lowest voltage is located; and if so, determining that the single battery has an internal short circuit.

Preferably, the internal short circuit detection apparatus provided by the present invention further includes:

a fourth determining unit 125, configured to determine an operating mode of a battery pack in the electric vehicle if the third determining unit 124 determines that the standing time is not greater than a preset standing time threshold;

a fifth determining unit 126 for determining an evaluation parameter of the battery pack in the operation mode;

the second detecting unit 127 is configured to determine that there is an internal short circuit in the battery pack if it is determined that the evaluation parameter in the working mode satisfies the internal short circuit fault detection condition in the working mode.

Preferably, the operation mode includes at least one of: a driving discharging mode, a constant current CC-constant voltage CV charging mode and a vehicle-mounted charging mode.

Preferably, if the operating mode is a vehicle-mounted charging mode, the evaluation parameters of the battery pack in the vehicle-mounted charging mode include an internal short circuit diagnosis flag TRS, a state of health SOH of the battery pack, a remaining capacity SOC of the battery pack, and a charging and discharging efficiency of the battery pack; and

the second detecting unit 127 is specifically configured to determine whether the evaluation parameter of the battery pack in the driving discharging mode meets an internal short circuit fault detection condition in the driving discharging mode when the electric vehicle is currently in the non-sleep state; when the internal short circuit fault detection condition under the vehicle-mounted charging mode is determined not to be met, determining whether the health condition SOH of the battery pack, the residual capacity SOC of the battery pack and the charging and discharging efficiency of the battery pack meet the internal short circuit fault detection condition under the vehicle-mounted charging mode or not when the value of the internal short circuit diagnosis mark TRS is determined to be a set value; and

the second detection unit 127 is further configured to determine a standing time of the electric vehicle when the electric vehicle is in a sleep state at present and is powered on again, and determine whether an internal short circuit exists in the battery pack according to an evaluation parameter of the battery pack corresponding to the standing time when it is determined that the standing time is greater than a set standing time threshold; when the internal short circuit of the battery pack is determined to be absent, determining whether the evaluation parameters of the battery pack in the driving discharge mode meet the internal short circuit fault detection conditions in the driving discharge mode; when the internal short circuit fault detection condition under the vehicle-mounted charging mode is determined not to be met, and the value of the internal short circuit diagnosis mark TRS is determined to be a set value, the state of health (SOH) of the battery pack, the residual capacity (SOC) of the battery pack and the charging and discharging efficiency of the battery pack are determined, and whether the internal short circuit fault detection condition under the vehicle-mounted charging mode is met or not is determined.

Preferably, the second detecting unit 127 is specifically configured to determine that the internal short circuit fault detection condition in the vehicle-mounted charging mode is satisfied when it is determined that the SOH is greater than the preset health condition threshold, the SOC is not greater than the preset remaining power threshold, and the charging and discharging efficiency of the battery pack is not greater than the preset charging and discharging efficiency threshold.

Preferably, if the operating mode is a driving discharge mode, the evaluation parameters of the battery pack in the driving discharge mode include SOC, minimum voltage and average voltage of the single battery, maximum temperature of the single battery, average temperature, maximum temperature, theoretical maximum temperature, internal resistance of the single battery corresponding to the maximum temperature, and average internal resistance; and

the second detecting unit 127 is specifically configured to determine the lowest voltage of the single batteries in the battery pack, the number of the battery module where the single battery corresponding to the lowest voltage is located, and the average voltage of the single batteries in the battery pack when it is determined that the SOC of the battery pack satisfies the remaining power range corresponding to the driving discharge mode; when the voltage difference value between the average voltage and the lowest voltage is larger than a preset second voltage difference value threshold value, determining the highest temperature of a single battery in the battery pack, the number of a battery module where the single battery corresponding to the highest temperature is located, the average temperature of the single battery, the theoretical highest temperature of the battery pack, and the internal resistance and the average internal resistance of the single battery corresponding to the highest temperature; when the temperature difference between the highest temperature and the average temperature is larger than a preset second temperature difference threshold value, whether the number of the battery module where the single battery corresponding to the lowest voltage is located is consistent with the number of the battery module where the single battery corresponding to the highest temperature is located is determined; if so, determining the theoretical highest temperature of the battery pack according to the initial temperature of the battery pack, the SOC and the SOH of the battery pack, the specific heat capacity coefficient of the battery pack and the discharge energy accumulated during the current electrification, which are recorded during the electrification of the vehicle; when the highest temperature is determined to be larger than the theoretical highest temperature, determining the average internal resistance of the single batteries of the battery pack and the internal resistance of the single battery corresponding to the highest temperature; and when the internal resistance of the single battery corresponding to the highest temperature is determined to be smaller than the average internal resistance and the SOH of the battery pack is determined to be larger than a preset health condition threshold value, determining that the internal short circuit fault detection condition under the driving discharge mode is met, and determining that the single battery corresponding to the highest temperature in the battery pack has an internal short circuit.

Preferably, if the operating mode is a constant-current CC-constant-voltage CV charging mode, the evaluation parameters of the battery pack in the CC-CV charging mode include: the remaining charging time, the first actual charging time, the second actual charging time, the first accumulated charge amount, the first charging amount, the second accumulated charge amount, and the second charging amount of the battery pack; and

the fifth determining unit 126 is specifically configured to estimate the remaining charging time of the battery pack according to the current SOC, SOH, capacity, current temperature, sampling current, and a predicted charging curve of the battery pack; when the voltage of the battery pack collected at present is determined to reach the set constant voltage, determining first actual charging time and first accumulated charge amount when the voltage in the constant current stage reaches the set constant voltage, and predicting first applied charging charge amount when the voltage in the constant current stage reaches the set constant voltage; and reducing the charging current, determining a second actual charging time and a second accumulated charge amount when the constant voltage stage current reaches the current corresponding to the charging end when the reduced charging current is determined to reach the current corresponding to the charging end, and predicting a second charge amount when the constant voltage stage current reaches the current corresponding to the charging end.

Preferably, the evaluation parameters of the battery pack in the CC-CV charging mode further include: the maximum temperature of a single battery in the battery pack, the theoretical maximum temperature of the battery pack, the internal resistance of the single battery corresponding to the maximum temperature and the average internal resistance of the single batteries of the battery pack; the residual charging time comprises a first residual charging time in a constant voltage stage and a second residual charging time in a constant current stage; and

the second detecting unit 127 is specifically configured to determine a first product of a sum of the first charging amount and the second charging amount and a micro short-circuit coefficient; determining a sum value between the first accumulated amount of charge and the second accumulated amount of charge; and determining that the first product is less than the sum; when the first residual charging time is determined to be greater than the first actual charging time and the second residual charging time is determined to be less than the second actual charging time, determining a sum of the first actual charging time and the second actual charging time, and determining a product of the residual charging time and a short-circuit fault coefficient in the battery pack; determining the maximum temperature of the single battery in the battery pack and the theoretical maximum temperature of the battery pack when the sum is determined to be greater than the product; when the highest temperature is determined to be larger than the theoretical highest temperature, determining the internal resistance of the single battery corresponding to the highest temperature and the average internal resistance of the single batteries of the battery pack; when the internal resistance of the single battery corresponding to the highest temperature is determined to be smaller than the average internal resistance, determining that a first ratio between the first charging load and the first accumulated charge is larger than a first internal short-circuit ratio threshold; and when determining that a second ratio between the second accumulated charge amount and the second charge amount to be charged is greater than a second internal short circuit ratio threshold value, determining that the single battery corresponding to the highest temperature in the battery pack has an internal short circuit.

For convenience of description, the above parts are separately described as modules (or units) according to functional division. Of course, the functionality of the various modules (or units) may be implemented in the same or in multiple pieces of software or hardware in practicing the invention.

Having described the method, apparatus, and electric vehicle for detecting short circuits in a battery pack according to exemplary embodiments of the present invention, a computing apparatus according to another exemplary embodiment of the present invention will be described next.

As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or program product. Thus, various aspects of the invention may be embodied in the form of: an entirely hardware embodiment, an entirely software embodiment (including firmware, microcode, etc.) or an embodiment combining hardware and software aspects that may all generally be referred to herein as a "circuit," module "or" system.

In some possible embodiments, a computing device according to the present invention may comprise at least one processing unit, and at least one memory unit. Wherein the storage unit stores program code, which, when executed by the processing unit, causes the processing unit to perform the steps of the method for detecting short circuit in a battery pack according to various exemplary embodiments of the present invention described above in this specification. For example, the processing unit may perform the short circuit detection procedure within the battery pack as in steps S11 to S13 shown in fig. 1.

The computing device 130 according to this embodiment of the invention is described below with reference to fig. 13. The computing device 130 shown in fig. 13 is only an example and should not bring any limitations to the functionality or scope of use of the embodiments of the present invention.

As shown in fig. 13, the computing apparatus 130 is embodied in the form of a general purpose computing device. Components of computing device 130 may include, but are not limited to: the at least one processing unit 131, the at least one memory unit 132, and a bus 133 connecting various system components (including the memory unit 132 and the processing unit 131).

Bus 133 represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, a processor, or a local bus using any of a variety of bus architectures.

The storage unit 132 may include readable media in the form of volatile memory, such as Random Access Memory (RAM)1321 and/or cache memory 1322, and may further include Read Only Memory (ROM) 1323.

Storage unit 132 may also include a program/utility 1325 having a set (at least one) of program modules 1324, such program modules 1324 including, but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may comprise an implementation of a network environment.

Computing device 130 may also communicate with one or more external devices 134 (e.g., keyboard, pointing device, etc.), with one or more devices that enable a user to interact with computing device 130, and/or with any devices (e.g., router, modem, etc.) that enable computing device 130 to communicate with one or more other computing devices. Such communication may occur via input/output (I/O) interfaces 135. Also, computing device 130 may communicate with one or more networks (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network, such as the internet) via network adapter 136. As shown, network adapter 136 communicates with other modules for computing device 130 over bus 133. It should be understood that although not shown in the figures, other hardware and/or software modules may be used in conjunction with computing device 130, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, among others.

In some possible embodiments, various aspects of the method for detecting short circuit in a battery pack provided by the present invention may also be implemented in the form of a program product, which includes program code for causing a computer device to execute the steps of the method for detecting short circuit in a battery pack according to various exemplary embodiments of the present invention described above in this specification when the program product runs on the computer device, for example, the computer device may execute the procedures for detecting short circuit in a battery pack in steps S11 to S13 shown in fig. 1.

The program product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

The program product for the battery pack internal short circuit detection method of the embodiment of the present invention may employ a portable compact disc read only memory (CD-ROM) and include program codes, and may be run on a computing device. However, the program product of the present invention is not limited in this regard and, in the present document, a readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

A readable signal medium may include a propagated data signal with readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A readable signal medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device over any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., over the internet using an internet service provider).

It should be noted that although several units or sub-units of the apparatus are mentioned in the above detailed description, such division is merely exemplary and not mandatory. Indeed, the features and functions of two or more of the units described above may be embodied in one unit, according to embodiments of the invention. Conversely, the features and functions of one unit described above may be further divided into embodiments by a plurality of units.

Moreover, while the operations of the method of the invention are depicted in the drawings in a particular order, this does not require or imply that the operations must be performed in this particular order, or that all of the illustrated operations must be performed, to achieve desirable results. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step execution, and/or one step broken down into multiple step executions.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A method for detecting a short circuit in a battery pack is characterized by comprising the following steps:

2. The method of claim 1, prior to determining the evaluation parameter of the battery pack corresponding to the resting time, further comprising:

3. The method of claim 2, wherein the evaluation parameters of the battery pack corresponding to the resting time comprise at least one of: the minimum voltage, the average voltage and the number of the battery module where the single battery corresponding to the minimum voltage is located, the temperature and the average temperature of the single battery in the battery pack.

4. The method according to claim 3, wherein determining whether there is an internal short circuit in the battery pack according to the evaluation parameter of the battery pack corresponding to the resting time specifically comprises:

determining the lowest voltage of the single batteries in the battery pack and the serial numbers of the battery modules where the single batteries corresponding to the lowest voltage are located;

determining an average voltage of the individual cells in the battery pack;

when the voltage difference value between the average voltage and the lowest voltage is larger than a preset first voltage difference value threshold value, respectively determining the temperature of each single battery in the battery pack and the average temperature of the single batteries;

for each of the first N single batteries with the respective temperatures, performing the following processes: when the temperature difference between the temperature of the single battery and the average temperature is larger than a preset first temperature difference threshold value, determining whether the number of the battery module where the single battery is located is consistent with the number of the battery module where the single battery corresponding to the lowest voltage is located; and if so, determining that the single battery has an internal short circuit.

5. The method of any of claims 1 to 4, further comprising:

if the standing time is not larger than a preset standing time threshold value, determining a working mode of a battery pack in the electric automobile; and are

Determining an evaluation parameter of the battery pack in the working mode;

and if the evaluation parameters in the working mode meet the internal short circuit fault detection conditions in the working mode, determining that the internal short circuit exists in the battery pack.

6. The method of claim 5, wherein the operating mode includes at least one of: a driving discharging mode, a constant current CC-constant voltage CV charging mode and a vehicle-mounted charging mode.

7. The method according to claim 6, wherein if the operation mode is an on-board charging mode, the evaluation parameters of the battery pack in the on-board charging mode include an internal short circuit diagnosis flag TRS, a state of health SOH of the battery pack, a remaining capacity SOC of the battery pack, and a charging and discharging efficiency of the battery pack; and determining whether the evaluation parameters in the working mode meet the internal short circuit fault detection conditions in the working mode, specifically comprising:

when the electric automobile is in a non-dormant state at present, determining whether the evaluation parameters of the battery pack in the driving discharge mode meet the internal short circuit fault detection conditions in the driving discharge mode;

when the internal short circuit fault detection condition under the vehicle-mounted charging mode is determined not to be met, determining whether the health condition SOH of the battery pack, the residual capacity SOC of the battery pack and the charging and discharging efficiency of the battery pack meet the internal short circuit fault detection condition under the vehicle-mounted charging mode or not when the value of the internal short circuit diagnosis mark TRS is determined to be a set value; and

when the electric automobile is in a dormant state at present and is electrified again, determining the standing time of the electric automobile, and when the standing time is determined to be larger than a set standing time threshold value, determining whether an internal short circuit exists in a battery pack according to an evaluation parameter of the battery pack corresponding to the standing time;

when the internal short circuit of the battery pack is determined to be absent, determining whether the evaluation parameters of the battery pack in the driving discharge mode meet the internal short circuit fault detection conditions in the driving discharge mode;

when the internal short circuit fault detection condition under the vehicle-mounted charging mode is determined not to be met, and the value of the internal short circuit diagnosis mark TRS is determined to be a set value, the state of health (SOH) of the battery pack, the residual capacity (SOC) of the battery pack and the charging and discharging efficiency of the battery pack are determined, and whether the internal short circuit fault detection condition under the vehicle-mounted charging mode is met or not is determined.

8. The method of claim 7, wherein determining whether the state of health (SOH) of the battery pack, the remaining capacity (SOC) of the battery pack and the charge-discharge efficiency of the battery pack satisfy the internal short circuit fault detection condition in the vehicle-mounted charging mode specifically comprises:

and when the SOH is determined to be larger than a preset health condition threshold value, the SOC is determined to be not larger than a preset residual electric quantity threshold value, and the charge-discharge efficiency of the battery pack is determined to be not larger than a preset charge-discharge efficiency threshold value, determining that the internal short circuit fault detection condition under the vehicle-mounted charging mode is met.

9. The method according to claim 6, wherein if the operation mode is a driving discharge mode, the evaluation parameters of the battery pack in the driving discharge mode include SOC, the lowest voltage of the single battery, the average voltage, the highest temperature of the single battery, the average temperature, the highest temperature, the theoretical highest temperature, the internal resistance of the single battery corresponding to the highest temperature, and the average internal resistance; and determining whether the evaluation parameters in the working mode meet the internal short circuit fault detection conditions in the working mode, specifically comprising:

when the SOC of the battery pack is determined to meet the remaining capacity range corresponding to the driving discharge mode, determining the lowest voltage of the single batteries in the battery pack, the serial number of the battery module where the single battery corresponding to the lowest voltage is located and the average voltage of the single batteries in the battery pack;

when the voltage difference value between the average voltage and the lowest voltage is larger than a preset second voltage difference value threshold value, determining the highest temperature of a single battery in the battery pack, the serial number of a battery module where the single battery corresponding to the highest temperature is located and the average temperature of the single battery; and are

When the temperature difference between the highest temperature and the average temperature is larger than a preset second temperature difference threshold value, determining whether the serial number of the battery module where the single battery corresponding to the lowest voltage is located is consistent with the serial number of the battery module where the single battery corresponding to the highest temperature is located;

if so, determining the theoretical highest temperature of the battery pack according to the initial temperature of the battery pack, the SOC and the SOH of the battery pack, the specific heat capacity coefficient of the battery pack and the discharge energy accumulated during the current electrification, which are recorded during the electrification of the vehicle;

when the highest temperature is determined to be larger than the theoretical highest temperature, determining the average internal resistance of the single batteries of the battery pack and the internal resistance of the single battery corresponding to the highest temperature;

and when the internal resistance of the single battery corresponding to the highest temperature is determined to be smaller than the average internal resistance and the SOH of the battery pack is determined to be larger than a preset health condition threshold value, determining that the internal short circuit fault detection condition under the driving discharge mode is met, and determining that the single battery corresponding to the highest temperature in the battery pack has an internal short circuit.

10. The method of claim 6, wherein if the operating mode is a constant current CC-constant voltage CV charging mode, the evaluation parameters of the battery pack in the CC-CV charging mode comprise: the remaining charging time, the first actual charging time, the second actual charging time, the first accumulated charge amount, the first charging amount, the second accumulated charge amount, and the second charging amount of the battery pack; and determining an evaluation parameter of the battery pack in the working mode, specifically comprising:

estimating the remaining charging time of the battery pack according to the current SOC, SOH, capacity, current temperature, sampling current and a predicted charging curve of the battery pack;

when the voltage of the battery pack collected at present is determined to reach the set constant voltage, determining first actual charging time and first accumulated charge amount when the voltage in the constant current stage reaches the set constant voltage, and predicting first applied charging charge amount when the voltage in the constant current stage reaches the set constant voltage; and

and reducing the charging current, determining a second actual charging time and a second accumulated charge amount when the constant voltage stage current reaches the current corresponding to the charging end when the reduced charging current is determined to reach the current corresponding to the charging end, and predicting a second charging charge amount when the constant voltage stage current reaches the current corresponding to the charging end.

11. The method of claim 10, wherein the evaluation parameters of the battery pack in the CC-CV charging mode further comprise: the maximum temperature of a single battery in the battery pack, the theoretical maximum temperature of the battery pack, the internal resistance of the single battery corresponding to the maximum temperature and the average internal resistance of the single batteries of the battery pack; the residual charging time comprises a first residual charging time in a constant voltage stage and a second residual charging time in a constant current stage; and if the evaluation parameters in the working mode meet the internal short circuit fault detection conditions in the working mode, determining that the internal short circuit exists in the battery pack, specifically comprising:

determining a first product of a sum of the first and second amounts of applied charge and a micro-short circuit coefficient;

determining a sum value between the first accumulated amount of charge and the second accumulated amount of charge; and are

Determining that the first product is less than the sum; and

when the first residual charging time is determined to be greater than the first actual charging time and the second residual charging time is determined to be less than the second actual charging time, determining a sum of the first actual charging time and the second actual charging time, and determining a product of the residual charging time and a short-circuit fault coefficient in the battery pack;

determining the maximum temperature of the single battery in the battery pack and the theoretical maximum temperature of the battery pack when the sum is determined to be greater than the product;

when the highest temperature is determined to be larger than the theoretical highest temperature, determining the internal resistance of the single battery corresponding to the highest temperature and the average internal resistance of the single batteries of the battery pack;

when the internal resistance of the single battery corresponding to the highest temperature is determined to be smaller than the average internal resistance, determining that a first ratio between the first charging load and the first accumulated charge is larger than a first internal short-circuit ratio threshold; and when determining that a second ratio between the second accumulated charge amount and the second charge amount to be charged is greater than a second internal short circuit ratio threshold value, determining that the single battery corresponding to the highest temperature in the battery pack has an internal short circuit.

12. A short circuit detection device in battery package, its characterized in that includes:

13. A computer-readable medium having stored thereon computer-executable instructions for performing the method of any one of claims 1 to 11.

14. An electric vehicle, comprising:

at least one processor; and

the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1 to 11.