A method for judging and disposing pressure difference risk of power storage battery system for electric bus

Abstract

The present application relates to electric vehicle battery risk discrimination technical field, especially, it relates to a kind of electric bus power battery system pressure difference risk discrimination and disposal method, comprising: power battery system pressure difference risk is divided into single system pressure difference, multiple system pressure difference and high-risk system pressure difference.The present application can be according to the risk level discrimination of power battery system pressure difference, respectively using different fault alarm light and vehicle end power control measures, high specification control disposal is carried out to the power battery with high security risk, and the risk of thermal runaway of power battery is greatly reduced;And according to the fusion analysis of SOC and voltage change trend at the time of alarm, it can accurately distinguish no security risk pressure difference and high security risk pressure difference, form different levels of vehicle end disposal strategy, on the one hand, it can avoid the problem that the risk is ignored when the pressure difference alarm disappears due to the change of SOC or the stop of charging in the existing pressure difference judgment method, on the other hand, it solves the problem that pressure difference security risk cannot be effectively distinguished.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicle battery risk discrimination, and particularly relates to a power battery system pressure difference risk discrimination and disposal method for electric buses. BACKGROUND

[0002] Electric buses have developed rapidly in recent years and have basically replaced traditional buses in first-tier and second-tier cities to become the main public transportation tool. Meanwhile, the safety situation of electric buses is not optimistic, and electric bus fire accidents occur from time to time. According to statistics, about 50% of electric vehicle fire accidents are caused by power batteries, and the main cause of power battery fire is thermal runaway of power batteries, and one of the important reasons for thermal runaway is power battery defects. Pressure difference is an important characteristic parameter reflecting battery defects, and is used as an important basis for vehicle battery fault alarm due to simple calculation method.

[0003] Under the comprehensive influence of the electric bus battery management system (BMS) alarm condition, alarm disappearance condition and battery characteristics, when the power battery occurs pressure difference alarm, the alarm can disappear and the vehicle can operate normally due to the change of SOC (state of charge / remaining capacity of the battery) or stop charging. This method often ignores the existing problems of the battery by the driver / owner, which causes a large number of batteries with safety hazards to continue to be used, leaving a major safety hazard for electric buses. In addition, there are many reasons for the pressure difference of the battery system, which can be divided into no safety risk pressure difference and high safety risk pressure difference according to the size of the safety risk. The no safety risk pressure difference refers to the pressure difference formed by the imbalance of the battery or the low / high power, which only needs to be balanced or does not need to be treated, and only affects the vehicle mileage without safety hazards. The high safety risk pressure difference refers to the pressure difference formed by the internal defects of the battery, such as micro-short circuit, individual battery self-discharge, etc. If the battery continues to serve, it will lead to the deterioration of the micro-short circuit, and even cause fire accidents, which needs to be replaced and treated. However, the existing pressure difference alarm only determines the fault according to the pressure difference threshold, which is single in function and cannot effectively distinguish the states of no risk, low risk and high risk of the battery. Moreover, the alarm is greatly affected by the change of SOC and is easy to disappear, which cannot control the vehicle and cannot accurately guide the maintenance scheme.

[0004] Based on the above background, a power battery system pressure difference risk discrimination and disposal method for electric buses is proposed to solve the problems. SUMMARY

[0005] Other features and advantages of the present application will be set forth in the following specification, and in part will become apparent to those skilled in the art upon examination of the specification or can be learned by practice of the application. The objects and other advantages of the application can be realized and attained by the structure particularly pointed out in the specification.

[0006] The present application aims to overcome the above-mentioned deficiencies, and provides a power storage system pressure difference risk discrimination and disposal method for electric buses.

[0007] To achieve the above-mentioned purpose, the technical solution of the present application is: a power storage system pressure difference risk discrimination and disposal method for electric buses, comprising: the power storage system pressure difference risk is divided into single system pressure difference, multiple system pressure difference and high-risk system pressure difference; wherein, the single system pressure difference: the bus vehicle controller has the function of recording the SOC value when the pressure difference exceeds the first threshold value, and the pressure difference is divided into two discrimination steps, when the power storage system pressure difference exceeds the first step or more, the corresponding power storage state of charge indicator light on the instrument is turned on, when the power storage system pressure difference exceeds the second step or more, the corresponding power storage fault signal light on the instrument is turned on; the multiple system pressure difference: the bus vehicle controller has the function of recording the number of pressure difference alarm and recording the corresponding low voltage single box position number function, when the number of single system pressure difference alarm exceeds the set value or more, the corresponding power storage fault signal light on the instrument is turned on; the high-risk system pressure difference: when the number of single system pressure difference alarm exceeds the set value or more, and at the same time is identified as a high-risk system pressure difference, the corresponding power storage fault signal light on the instrument is turned on.

[0008] In some embodiments, the two discrimination steps of single system pressure difference are 350 mV and 500 mV respectively.

[0009] In some embodiments, when the single system pressure difference of the first step corresponds to the state of charge indicator light turned on, the instrument will also have a text prompt that the battery pressure difference is too large, and the power battery manufacturer is reported for repair and processing.

[0010] In some embodiments, when the single system pressure difference of the second step corresponds to the fault signal light turned on, the instrument will also have a text prompt that the battery pressure difference is too large, and the power battery manufacturer is reported for repair and processing, and a serious overcharge alarm signal of the battery is sent to the enterprise platform.

[0011] In some embodiments, when the multiple system pressure difference corresponds to the fault signal light turned on, the instrument will also have a text prompt that the battery pressure difference is too large, and the power battery manufacturer is reported for repair and processing, and a serious pressure difference alarm signal of the battery is sent to the enterprise platform.

[0012] In some embodiments, the set value of the alarm number of multiple system pressure difference and high-risk system pressure difference is 5 times.

[0013] In some embodiments, when the high-risk system pressure difference corresponds to the fault signal light turned on, the instrument will also have a text prompt that the battery monomer is abnormal, the vehicle controller issues a stop command, the drive power limitation signal light is turned on, and a request for rescue information is sent to the enterprise platform.

[0014] In some embodiments, the identification calculation of the high-risk system pressure difference is according to the formula as follows:

[0015] ,

[0016] ,

[0017] In the formula, the time and SOC value corresponding to the record pressure difference exceeding the first threshold value are recorded as tal and SOCal respectively, and the corresponding information of each alarm is recorded as arrays DV_SOC and DV_t respectively. The Pearson coefficient p1 between the two arrays is calculated according to the formula.

[0018] In some embodiments, the identification calculation of the high-risk system pressure difference is according to the formula as follows:

[0019] ,

[0020] In the formula, the minimum single cell voltage value during the standing process after the battery system pressure difference alarm is recorded, and the corresponding values at the time of pressure difference alarm are recorded as t(1) and Vmin(1). The corresponding values at the time when the standing ends, i.e. before the next charging and discharging starts, are recorded as t(k) and Vmin(k). The voltage drop coefficient p2 is calculated according to the formula, where c is a constant, which can be set as 1-2 times of the voltage error, or 1-2 times of Vmax(k)-Vmax(1).

[0021] By adopting the technical solutions described above, the application has the following beneficial effects:

[0022] 1. According to the risk level of the power battery system pressure difference, different fault alarm lights and vehicle end power control measures are used to control and dispose the power battery with high safety hidden danger, which greatly reduces the risk of thermal runaway of the power battery and ensures the safety of the electric bus.

[0023] 2. The vehicle controller has the functions of recording the number of pressure difference alarm occurrences and recording the low voltage single cell box position number corresponding to the large pressure difference, which increases the alarm frequency statistical function. After multiple alarms occur, the vehicle end can set a high level of risk control.

[0024] 3. According to the fusion analysis of the SOC and voltage change trend at the time of alarm, the safe pressure difference and the high safety risk pressure difference can be accurately distinguished, and different levels of vehicle end disposal strategies are formed. On the one hand, it can avoid the problem that the risk is ignored when the pressure difference alarm disappears due to the change of SOC or the stop of charging in the existing pressure difference judgment method. On the other hand, it solves the problem of being unable to effectively distinguish the safety risk of pressure difference.

[0025] 4、The embodiment of the present application is simple and easy to implement, requires very small computing power, and has the feasibility of implementing engineering applications at the vehicle end.

[0026] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure.

[0027] In order to make the above beneficial effects and other purposes, features and advantages of the present application more obvious, easy to understand, one or more preferred embodiments are specifically described below, and will be described in detail as follows. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below with reference to the embodiments, so that the application of technical means to solve technical problems and achieve technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, each embodiment in the present application and each feature in each embodiment can be combined with each other, and the technical solutions formed thereby are within the protection scope of the present application.

[0029] Meanwhile, in the following description, many specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without the specific details or in a manner other than the specific manner described.

[0030] The present application provides a power storage system pressure difference risk discrimination and disposal method for electric buses, comprising: power storage system pressure difference risk is divided into single system pressure difference, multiple system pressure difference and high-risk system pressure difference; wherein, single system pressure difference: the vehicle controller has the function of recording the SOC value when the pressure difference exceeds the first threshold value, and the pressure difference is divided into two discrimination steps, when the power storage system pressure difference exceeds the first step, the corresponding power storage state of charge indicator light on the instrument is turned on, when the power storage system pressure difference exceeds the second step, the corresponding power storage fault signal light on the instrument is turned on; multiple system pressure difference: the vehicle controller has the function of recording the number of pressure difference alarm occurrences and recording the corresponding low voltage monomer box position number function when the pressure difference is large, when the number of single system pressure difference alarms of the power storage battery exceeds the set value, the corresponding power storage fault signal light on the instrument is turned on; high-risk system pressure difference: when the number of single system pressure difference alarms of the power storage battery exceeds the set value, and at the same time is identified as a high-risk system pressure difference, the corresponding power storage fault signal light on the instrument is turned on.

[0031] In the embodiment, the electric vehicle power has the functions of recording the SOC value when the differential pressure exceeds the first threshold value, recording the number of differential pressure alarm occurrences, and recording the position number of the low-voltage single cell box corresponding to the differential pressure. When the electric vehicle power battery determines the single system differential pressure, the power battery system differential pressure exceeds the first step, and the SOC indicator light on the instrument is turned on. When the power battery system differential pressure exceeds the second step, the corresponding fault signal light on the instrument is turned on. When the multiple system differential pressure is determined, the number of single system differential pressure alarms is recorded. When the cumulative value exceeds the set value, the corresponding fault signal light on the instrument is turned on. When the high-risk system differential pressure is determined, the corresponding fault signal light on the instrument is turned on based on the multiple system differential pressure and the battery micro-short circuit (high-risk system differential pressure) fault. Thus, the safe system differential pressure and the high-risk system differential pressure can be distinguished, different levels of vehicle end treatment strategies are formed, and the problems of the existing differential pressure judgment method, such as the disappearance of the differential pressure alarm when the SOC changes or stops charging, and the inability to effectively distinguish the safety risk of the differential pressure, are solved.

[0032] According to some embodiments of the present application, the two determination steps of the single system differential pressure are 350 mV and 500 mV, respectively. 350 mV and 500 mV are the high value and the higher value of the battery system differential pressure, respectively, which can effectively distinguish the safety of the battery.

[0033] According to some embodiments of the present application, when the single system differential pressure of the first step corresponds to the SOC indicator light turned on, the instrument will also have a text prompt that the battery differential pressure is too large, and the power battery manufacturer is reported for repair. The text prompt is added to the indicator light turned on, and the alarm prompt is more comprehensive, so that the driver can quickly find the working condition of the battery, and the battery manufacturer can be reported to contact and remind the driver in time, which is safer and the battery can be checked and processed in time.

[0034] According to some embodiments of the present application, when the single system differential pressure of the second step corresponds to the fault signal light turned on, the instrument will also have a text prompt that the battery differential pressure is too large, and the power battery manufacturer is reported for repair, and a serious overcharge alarm signal is sent to the enterprise platform. The text prompt is added to the indicator light turned on, and the alarm prompt is more comprehensive, so that the driver can quickly find the working condition of the battery, and the battery manufacturer can be reported to contact and remind the driver in time, which is safer and the battery can be checked and processed in time.

[0035] According to some embodiments of the present application, optionally, when the multiple system pressure difference corresponds to the failure signal light, the instrument will also have a text prompt that the battery pressure difference is too large, and the power battery manufacturer is reported for maintenance processing, and the enterprise platform is sent a battery serious pressure difference alarm signal. The warning prompt will be more comprehensive when the indicator light is on with a text prompt, so that the driver can quickly find out the working condition of the storage battery, and the battery manufacturer is also reported, so that the battery manufacturer can timely contact the driver, which is safer and the battery can be checked and processed in time.

[0036] According to some embodiments of the present application, optionally, the alarm frequency setting value of the multiple system pressure difference and the high-risk system pressure difference is 5 times. The number of times is the acceptable number of times of the system pressure difference of the battery, and more than the number of times means that the judgment is correct, and measures need to be taken to handle it in time.

[0037] According to some embodiments of the present application, optionally, when the high-risk system pressure difference corresponds to the failure signal light, the instrument will also have a text prompt that the battery cell is abnormal, the vehicle control unit issues a stop driving instruction, the driving power limit signal light is on, and a request for rescue information is sent to the enterprise platform. The warning prompt will be more comprehensive when the indicator light is on with a text prompt, so that the driver can quickly find out the working condition of the storage battery, and the vehicle control unit prompts the driver to stop driving again, and sends a rescue information, so that the driver knows that the vehicle should stop running and wait for rescue to avoid continuing to run and causing a fire accident of the battery.

[0038] According to some embodiments of the present application, optionally, the identification calculation of the high-risk system pressure difference is based on the following formula:

[0039] ,

[0040] ,

[0041] In the formula, the time and SOC value corresponding to the recorded pressure difference exceeding the first threshold value are recorded as tal and SOCal, respectively, and the corresponding information of each alarm is recorded as arrays DV_SOC and DV_t, respectively. The Pearson coefficient p1 between the two arrays is calculated according to the formula. In addition, p1 can also be equal to the slope of the linear fitting of the array DV_SOC and DV_t.

[0042] From the above formula, it can be seen that the formula is a Pearson coefficient calculation formula, and the Pearson coefficient p1 can be calculated. When the absolute value of p1 is less than a set threshold value, it is judged that it is not a high-risk system pressure difference, and on the contrary, when the absolute value of p1 is greater than the set value, it is judged that the safety risk of the system pressure difference is high.

[0043] According to some embodiments of the present application, optionally, the identification calculation of the high-risk system pressure difference is according to the following formula:

[0044] ,

[0045] In the formula, the minimum single cell voltage value during the standing process after recording the battery system pressure difference alarm, the corresponding value at the time of pressure difference alarm is recorded as t(1) and Vmin(1), and the corresponding value at the time of the end of standing, i.e., before the next charging and discharging, is recorded as t(k) and Vmin(k). The voltage drop coefficient p2 is calculated according to the formula, wherein c is a constant, which can be set to 1-2 times of the voltage error, or set to 1-2 times of Vmax(k)-Vmax(1).

[0046] It can be known from the above formula that the formula is a linear fitting calculation formula. When the high-risk system pressure difference occurs, the voltage drop coefficient p2 is negative, and the negative value is also less than the set threshold and greater than the constant c, indicating that it is out of the error range, so that the system pressure difference can be determined.

[0047] According to some embodiments of the present application, optionally, the strategy can be applied to the vehicle control system VCU, and also can be applied to the battery management system BMS.

[0048] It should be understood that the embodiments disclosed in the present application are not limited to the specific processing steps or materials disclosed herein, but should extend to such equivalent alternatives of the features understood by those skilled in the related art. It should also be understood that the terms used herein are only for the purpose of describing the specific embodiments and do not mean limitation.

[0049] The "embodiment" mentioned in the specification means that the specific features or characteristics described in connection with the embodiment are included in at least one embodiment of the present application. Therefore, the phrase or "embodiment" appearing throughout the specification does not necessarily mean the same embodiment.

[0050] In addition, the described features or characteristics can be combined into one or more embodiments in any other suitable way. In the above description, some specific details, such as thickness, number, etc., are provided to provide a comprehensive understanding of the embodiments of the present application. However, those skilled in the related art will understand that the present application can be implemented without one or more of the above specific details or can be implemented using other methods, components, materials, etc.

Claims

1. A method for identifying and handling differential voltage risks in a power battery system for electric buses, characterized in that, include: The differential pressure risk of power battery systems is divided into single system differential pressure, multiple system differential pressure, and high-risk system differential pressure; among them, Single system differential pressure: The bus controller has the function of recording the SOC value when the differential pressure exceeds the first differential pressure threshold. The differential pressure is divided into two discrimination levels. When the differential pressure of the power battery system exceeds the first level, the corresponding power battery charge status indicator light on the instrument will light up. When the differential pressure of the power battery system exceeds the second level, the corresponding power battery fault signal light on the instrument will light up. Multiple system differential pressure: The bus controller has the function of recording the number of differential pressure alarms and the function of recording the location number of the low voltage cell box corresponding to the large differential pressure. When the number of single system differential pressure alarms of the power battery exceeds the set value, the corresponding power battery fault indicator light on the instrument will light up. High-risk system differential pressure: When the number of single-time system differential pressure alarms for the power battery exceeds the set value, and it is simultaneously identified as a high-risk system differential pressure, the corresponding power battery fault indicator light on the instrument will illuminate. The calculation formula for identifying high-risk system differential pressure is as follows: ， ， In the formula, the time and SOC value corresponding to the pressure difference exceeding the first threshold are recorded as tal and SOCal, respectively. The corresponding information of each alarm is recorded as arrays DV_SOC and DV_t. The Pearson coefficient p1 between the two arrays is calculated according to the formula. When p1 is greater than the set threshold, it is determined to be a high-risk system pressure difference. When p1 is less than the set threshold, it is a non-high-risk system pressure difference.

2. The method for identifying and handling differential voltage risks in a power battery system for electric buses according to claim 1, characterized in that, The two discrimination levels for single system pressure difference are 350 mV and 500 mV.

3. A method for identifying and handling differential voltage risk in a power battery system for electric buses according to claim 1 or 2, characterized in that, When the charge status indicator light corresponding to the single system differential pressure of the first stage lights up, the instrument will also display a text message indicating that the battery differential pressure is seriously too high, and report it to the power battery manufacturer for repair.

4. A method for identifying and handling differential voltage risk in a power battery system for electric buses according to claim 1 or 2, characterized in that, When the fault indicator light corresponding to the single system differential pressure of the second stage illuminates, the instrument will also display a text message indicating that the battery differential pressure is too high, report the issue to the power battery manufacturer for repair, and send a battery overcharge alarm signal to the enterprise platform.

5. The method for identifying and handling differential voltage risks in a power battery system for electric buses according to claim 1, characterized in that, When the fault indicator light corresponding to the system differential pressure illuminates multiple times, the instrument panel will also display a text message indicating that the battery differential pressure is too high, report the issue to the power battery manufacturer for repair, and send a severe battery differential pressure alarm signal to the enterprise platform.

6. A method for identifying and handling differential voltage risk in a power battery system for electric buses according to claim 1 or 5, characterized in that, The alarm count set for both multiple system differential pressure and high-risk system differential pressure is 5.

7. The method for identifying and handling differential voltage risks in a power battery system for electric buses according to claim 1, characterized in that, When the fault indicator light corresponding to the high-risk system differential pressure illuminates, the instrument panel will also display a text message indicating that the battery cell is abnormal. The vehicle controller will issue a stop command, the drive power limit indicator light will illuminate, and a request for assistance will be sent to the enterprise platform.

8. The method for identifying and handling differential voltage risks in a power battery system for electric buses according to claim 1, characterized in that, The formula for identifying and calculating the differential pressure in high-risk systems is as follows: In the formula, the lowest single-cell voltage value during the resting process after the battery system differential pressure alarm is recorded. The corresponding values ​​at the time of the differential pressure alarm are recorded as t(1) and Vmin(1). The corresponding values ​​at the time of the end of the resting process, i.e. before the start of the next charge and discharge, are recorded as t(k) and Vmin(k). The voltage drop coefficient p2 is calculated according to the formula, where c is a constant, which can be set to 1 to 2 times the voltage error, or set to 1 to 2 times Vmax(k) - Vmax(1).

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