Differential pressure risk distinguishing and handling method for power storage battery system for electric motor coach

Abstract

The invention relates to the technical field of electric vehicle storage battery risk judgment, in particular to a differential pressure risk judgment and disposal method for a power storage battery system for an electric bus, which comprises the step of dividing the differential pressure risk of the power storage battery system into single system differential pressure, multi-time system differential pressure and high-risk system differential pressure. According to the invention, different fault alarm lamps and vehicle end power management and control measures can be respectively adopted according to the judgment of different risk levels of the voltage difference of the power battery system, high-specification management and control treatment is carried out on the power battery with high potential safety hazards, and the risk of thermal runaway of the power battery is greatly reduced; and according to the fusion analysis of the SOC and the voltage change trend at the alarm moment, the non-safety-risk voltage difference and the high-safety-risk voltage difference can be accurately distinguished, and different levels of vehicle end processing strategies are formed, so that on one hand, the problem that the risk is ignored due to the disappearance of the voltage difference alarm when the SOC is changed or charging is stopped in the existing voltage difference judgment method can be avoided; on the other hand, the problem that differential pressure safety risks cannot be effectively distinguished is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of risk discrimination of electric vehicle storage batteries, and particularly relates to a method for discriminating and disposing of differential pressure risks of a power battery system for an electric bus. Background Art

[0002] After several years of rapid development, electric buses have basically replaced traditional buses in first- and second-tier cities and become the main public transportation vehicles. At the same time, the safety situation of electric buses is not optimistic, and electric bus fires occur from time to time. According to statistics, about 50% of electric vehicle fires are caused by power batteries. The main reason for power battery fires is thermal runaway of the power battery, and one of the important reasons for thermal runaway is power battery defects. Differential pressure is an important characteristic parameter reflecting battery defects and is used as an important basis for vehicle battery fault alarms because of its simple calculation method.

[0003] Affected by the comprehensive factors such as the alarm conditions, alarm disappearance conditions, and battery characteristics of the electric bus battery management system (BMS), when a differential pressure alarm occurs in the power battery, the alarm can disappear and the vehicle can operate normally when the state of charge (SOC) of the battery changes or charging stops. This method often ignores the problems existing in the storage battery by drivers / vehicle owners, allowing a large number of batteries with potential safety hazards to continue to be used, leaving major safety hazards for electric buses. In addition, there are various reasons for the generation of differential pressure in the battery system. According to the level of safety risk, it can be divided into differential pressure without safety risk and differential pressure with high safety risk. Among them, differential pressure without safety risk refers to the differential pressure formed by the battery due to unevenness or too low / high battery power, which only needs to be balanced or does not need to be processed, only affecting the vehicle driving range and having no safety hazard; differential pressure with high safety risk refers to the differential pressure formed by the battery due to internal defects causing micro-short circuits or self-discharge of individual battery cells. If the battery continues to be used, the micro-short circuit will deteriorate, and serious cases can lead to accidents such as fires, and the battery box needs to be replaced for treatment. However, the existing differential pressure alarm only determines faults based on the differential pressure threshold, with a single function, unable to effectively distinguish the states of the battery such as no risk, low risk, and high risk, and having the problem of being greatly affected by SOC changes and being easily disappeared, unable to control the vehicle and accurately guide the maintenance plan.

[0004] Based on the above background, a method for discriminating and disposing of differential pressure risks of a power battery system for an electric bus is proposed to solve the problems raised. Summary of the Invention

[0005] Other features and advantages of the present invention will be described in the following specification, and will become apparent in part from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification.

[0006] The object of the present invention is to overcome the above deficiencies and provide a method for discriminating and disposing of the differential pressure risk of a power battery system for an electric bus.

[0007] To achieve the above object, the technical solution of the present invention is: a method for discriminating and disposing of the differential pressure risk of a power battery system for an electric bus, including: the differential pressure risk of the power battery system is divided into single-system differential pressure, multi-system differential pressure and high-risk system differential pressure; among them, single-system differential pressure: the vehicle controller of the bus has the function of recording the SOC value at the moment when the differential pressure exceeds the first differential pressure threshold, and the differential pressure is divided into two discrimination levels. When the differential pressure of the power battery system exceeds the first level, the corresponding state-of-charge indicator light of the power battery on the instrument panel lights up. When the differential pressure of the power battery system exceeds the second level, the corresponding power battery fault indicator light on the instrument panel lights up; multi-system differential pressure: the vehicle controller of the bus has the function of recording the number of differential pressure alarms and the function of recording the position number of the low-voltage single-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 panel lights up; high-risk system differential pressure: when the number of single-system differential pressure alarms of the power battery exceeds the set value and is simultaneously identified as a high-risk system differential pressure, the corresponding power battery fault indicator light on the instrument panel lights up.

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

[0009] In some embodiments, when the state-of-charge indicator light corresponding to the single-system differential pressure of the first level lights up, there will also be a text prompt on the instrument panel that the battery differential pressure is seriously too large, and it is reported to the power battery manufacturer for repair.

[0010] In some embodiments, when the fault indicator light corresponding to the single-system differential pressure of the second level lights up, there will also be a text prompt on the instrument panel that the battery differential pressure is seriously too large, and it is reported to the power battery manufacturer for repair, and a battery serious overcharge alarm signal is sent to the enterprise platform.

[0011] In some embodiments, when the fault indicator light corresponding to the multi-system differential pressure lights up, there will also be a text prompt on the instrument panel that the battery differential pressure is seriously too large, and it is reported to the power battery manufacturer for repair, and a battery serious differential pressure alarm signal is sent to the enterprise platform.

[0012] In some embodiments, the set values of the number of alarms discriminated by the multi-system differential pressure and the high-risk system differential pressure are both 5 times.

[0013] In some embodiments, when the fault indicator light corresponding to the high-risk system differential pressure lights up, there will also be a text prompt on the instrument panel that the battery single cell is abnormal, the vehicle controller issues a stop driving command, the drive power limit indicator light lights up, and a request for rescue information is sent to the enterprise platform.

[0014] In some embodiments, the identification and calculation of the differential pressure of the high-risk system are based on the following formula:

[0015] DV_SOC = [SOC al (1), SOC al (2),..., SOC al (n)]

[0016] DV_t = [t al (1), t al (2),..., t al (n)],

[0017] p 1 = corr(DV_SOC, DV_t),

[0018] In the formula, record the time and SOC value corresponding to the differential pressure exceeding the first threshold, denoted as tal and SOCal respectively, and record the corresponding information of each alarm as arrays DV_SOC and DV_t respectively. Calculate the Pearson coefficient p1 between the two arrays according to the formula.

[0019] In some embodiments, the identification and calculation of the differential pressure of the high-risk system are based on the following formula:

[0020]

[0021] In the formula, record the lowest single-cell voltage value during the static process after the differential pressure alarm of the battery system. Denote the corresponding values at the moment of differential pressure alarm as t(1) and Vmin(1), and the corresponding values at the moment before the next charge and discharge starts after the static state ends as t(k) and Vmin(k). Calculate the voltage drop coefficient p2 according to the formula, where c is a constant, which can be set to 1 - 2 times the voltage error, or set to 1 - 2 times of Vmax(k) - Vmax(1).

[0022] By adopting the above technical solutions, the beneficial effects of the present invention are as follows:

[0023] 1. According to the discrimination of different risk levels of the differential pressure of the power battery system, different fault alarm lights and vehicle-end power control measures are respectively adopted to conduct high-standard control and disposal of the power battery with high safety hazards, greatly reducing the risk of thermal runaway of the power battery and ensuring the safety of electric buses;

[0024] 2. The vehicle controller has the functions of recording the number of differential pressure alarms and recording the position number of the low-voltage single-cell box corresponding to the large differential pressure, and adding the alarm number statistics function. After multiple alarms occur, the vehicle-end can set a higher-level risk control accordingly;

[0025] 3. Based on the fusion analysis of the SOC and voltage change trends at the alarm moment, it is possible to accurately distinguish between non - safety - risk pressure differences and high - safety - risk pressure differences, and form vehicle - end disposal strategies at different levels. On the one hand, it can avoid the problem that the existing pressure - difference judgment method ignores the risk when the pressure - difference alarm disappears due to the change of SOC or the stop of charging. On the other hand, it solves the problem of being unable to effectively distinguish the safety risks of pressure differences.

[0026] 4. The implementation mode of the present invention is simple and easy to implement, requires extremely low computing power, and has the feasibility of realizing engineering applications at the vehicle end.

[0027] 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.

[0028] Undoubtedly, such purposes of the present invention and other purposes will become more obvious after the detailed description of the preferred embodiments below.

[0029] To make the above - mentioned beneficial effects, other purposes, features and advantages of the present invention more obvious and understandable, one or several preferred embodiments are specifically given below and described in detail as follows. Detailed implementation mode

[0030] The following will combine the embodiments to detail the implementation mode of the present invention, so as to fully understand how the present invention uses technical means to solve technical problems and the implementation process of achieving technical effects and implement accordingly. It should be noted that as long as there is no conflict, the various embodiments in the present invention and the various features in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0031] At the same time, in the following description, many specific details are set forth for the purpose of explanation to provide a thorough understanding of the embodiments of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without these specific details or in the specific ways described herein.

[0032] The present invention provides a method for discriminating and disposing of the pressure difference risk of a power battery system for an electric bus, including: the pressure difference risks of the power battery system are divided into single-system pressure difference, multi-system pressure difference, and high-risk system pressure difference; among them, for the single-system pressure difference: the vehicle controller of the bus has the function of recording the SOC value at the moment when the pressure difference exceeds the first pressure difference threshold, and the pressure difference is divided into two discrimination levels. When the pressure difference of the power battery system exceeds the first level, the corresponding power battery state-of-charge indicator light on the instrument panel lights up. When the pressure difference of the power battery system exceeds the second level, the corresponding power battery fault indicator light on the instrument panel lights up; for the multi-system pressure difference: the vehicle controller of the bus has the function of recording the number of times of pressure difference alarms and the function of recording the position number of the low-voltage single-cell box corresponding to the large pressure difference. When the number of times of single-system pressure difference alarms of the power battery exceeds the set value, the corresponding power battery fault indicator light on the instrument panel lights up; for the high-risk system pressure difference: when the number of times of single-system pressure difference alarms of the power battery exceeds the set value and is simultaneously identified as a high-risk system pressure difference, the corresponding power battery fault indicator light on the instrument panel lights up.

[0033] In this embodiment, the power of the electric bus has the function of recording the SOC value at the moment when the pressure difference exceeds the first pressure difference threshold, the function of recording the number of times of pressure difference alarms, and the function of recording the position number of the low-voltage single-cell box corresponding to the large pressure difference. When discriminating the single-system pressure difference of the power battery of the electric bus, if the pressure difference of the power battery system exceeds the first level, the instrument panel will make the corresponding state-of-charge indicator light light up. If the pressure difference of the power battery system exceeds the second level, the instrument panel will make the corresponding fault indicator light light up; when discriminating the multi-system pressure difference, the number of times of single-system pressure difference alarms is statistically recorded. After the cumulative number exceeds the set value, the instrument panel will make the corresponding fault indicator light light up; when discriminating the high-risk system pressure difference, on the basis of discriminating the multi-system pressure difference and when the battery also has faults such as micro-short circuit (high-risk system pressure difference), the instrument panel will make the corresponding fault indicator light light up. Thus, the pressure difference of the system without safety risk and the pressure difference of the system with high safety risk can be distinguished, and different levels of vehicle-end disposal strategies can be formed. On the one hand, it can avoid the problem that the existing pressure difference judgment method ignores the risk when the pressure difference alarm disappears due to the change of SOC or the stop of charging. On the other hand, it can solve the problem of being unable to effectively distinguish the safety risk of the pressure difference.

[0034] According to some embodiments of the present application, optionally, the two discrimination levels of the single-system pressure difference are 350 mV and 500 mV respectively. 350 mV and 500 mV are respectively the high value and the relatively high value of the battery system pressure difference. Judging from these two levels can effectively distinguish whether the storage battery is safe.

[0035] According to some embodiments of the present application, optionally, when the state-of-charge indicator light corresponding to the single-system pressure difference of the first step is on, there will also be a text prompt on the instrument indicating that the battery pressure difference is seriously too large, and it is reported to the power battery manufacturer for repair. Adding a text prompt while the indicator light is on will make the alarm prompt more comprehensive, enabling the driver to more quickly discover the working condition of the storage battery, and it is also reported to the battery manufacturer, enabling the battery manufacturer to timely contact and remind the driver, with higher safety, and the battery can be timely inspected and processed.

[0036] According to some embodiments of the present application, optionally, when the fault signal light corresponding to the single-system pressure difference of the second step is on, there will also be a text prompt on the instrument indicating that the battery pressure difference is seriously too large, and it is reported to the power battery manufacturer for repair, and a battery severe overcharge alarm signal is sent to the enterprise platform. Adding a text prompt while the indicator light is on will make the alarm prompt more comprehensive, enabling the driver to more quickly discover the working condition of the storage battery, and it is also reported to the battery manufacturer, enabling the battery manufacturer to timely contact and remind the driver, with higher safety, and the battery can be timely inspected and processed.

[0037] According to some embodiments of the present application, optionally, when the fault signal light corresponding to the multiple-system pressure difference is on, there will also be a text prompt on the instrument indicating that the battery pressure difference is seriously too large, and it is reported to the power battery manufacturer for repair, and a battery severe pressure difference alarm signal is sent to the enterprise platform. Adding a text prompt while the indicator light is on will make the alarm prompt more comprehensive, enabling the driver to more quickly discover the working condition of the storage battery, and it is also reported to the battery manufacturer, enabling the battery manufacturer to timely contact and remind the driver, with higher safety, and the battery can be timely inspected and processed.

[0038] According to some embodiments of the present application, optionally, the set values of the alarm times determined by the multiple-system pressure difference and the high-risk system pressure difference are both 5 times. This number is the acceptable number of times for the battery to have a system pressure difference. Exceeding this number indicates that the discrimination is correct, and timely measures need to be taken for processing.

[0039] According to some embodiments of the present application, optionally, when the fault signal light corresponding to the high-risk system pressure difference is on, there will also be a text prompt on the instrument indicating that the battery cell is abnormal, the vehicle controller issues a stop driving command, the drive power limit indicator light is on, and a request for rescue information is sent to the enterprise platform. Adding a text prompt while the indicator light is on will make the alarm prompt more comprehensive, enabling the driver to more quickly discover the working condition of the storage battery, and the vehicle controller further prompts the driver with a stop driving command and simultaneously sends a rescue information, enabling the driver to learn that the vehicle should stop running and wait for rescue to avoid accidents such as battery fires caused by continued driving.

[0040] According to some embodiments of the present application, optionally, the identification and calculation of the pressure difference of the high-risk system are based on the following formula:

[0041] DV_SOC = [SOC al (1), SOC al (2),..., SOC al (n)]

[0042] DV_t = [t al (1), t al (2),..., t al (n)],

[0043] p 1 = corr(DV_SOC, DV_t),

[0044] In the formula, record the time and SOC value corresponding to the pressure difference exceeding the first threshold, denoted as tal and SOCal respectively, and record the corresponding information of each alarm as arrays DV_SOC and DV_t respectively. Calculate the Pearson coefficient p1 between the two arrays according to the formula. In addition, p1 can also be equal to the slope of the linear fit of the arrays DV_SOC and DV_t.

[0045] From the above formula, it can be known that this formula is the Pearson coefficient calculation formula, and the Pearson coefficient p1 can be calculated. When the absolute value of p1 is less than the set threshold, it is determined that it is not the pressure difference of the high-risk system. On the contrary, when the absolute value of p1 is greater than the set value, it is determined that the safety risk of the system pressure difference is high.

[0046] According to some embodiments of the present application, optionally, the identification and calculation of the pressure difference of the high-risk system are based on the following formula:

[0047]

[0048] In the formula, record the lowest single-cell voltage value during the static process after the battery system pressure difference alarm. The corresponding values at the moment of the pressure difference alarm are denoted as t(1) and Vmin(1), and the corresponding values at the moment when the static process ends, that is, before the next charge and discharge starts, are denoted as t(k) and Vmin(k). Calculate the voltage drop coefficient p2 according to the formula, where c is a constant, which can be set to 1-2 times the voltage error, or set to 1-2 times of Vmax(k) - Vmax(1).

[0049] From the above formula, it can be known that this formula is the linear fit calculation formula. When there is a pressure difference of the high-risk system, the voltage drop coefficient p2 is negative, and this negative value is less than the set threshold and greater than the constant c, indicating that it is outside the error range, so it can be determined that the system pressure difference is high.

[0050] According to some embodiments of the present application, optionally, this strategy can be applied to the vehicle control unit (VCU) of the whole vehicle, or can also be applied to the battery management system (BMS).

[0051] It should be understood that the embodiments disclosed in the present invention are not limited to the specific processing steps or materials disclosed herein, but should extend to equivalent alternatives of such features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and do not imply limitation.

[0052] The "embodiments" mentioned in the specification mean that the specific features or characteristics described in connection with the embodiments are included in at least one embodiment of the present invention. Therefore, the phrase "embodiments" that appears throughout the specification does not necessarily refer to the same embodiment.

[0053] In addition, the described features or characteristics can be combined in any other suitable way into one or more embodiments. In the above description, some specific details, such as thickness, quantity, etc., are provided to provide a comprehensive understanding of the embodiments of the present invention. However, those skilled in the relevant art will understand that the present invention can be implemented without one or more of the above specific details or can also be implemented using other methods, components, materials, etc.

Claims

1. A method for identifying and handling pressure difference risks in a power battery system for an electric bus, characterized in that: include: The pressure difference risk of power battery system is divided into single system pressure difference, multiple system pressure difference and high-risk system pressure difference; among them, Single system pressure difference: The bus vehicle controller has the function of recording the SOC value when the pressure difference exceeds the first pressure difference threshold, and the pressure difference is divided into two discrimination levels. When the power battery system pressure difference exceeds the first level, the corresponding power battery charge status indicator on the instrument lights up; when the power battery system pressure difference exceeds the second level, the corresponding power battery fault signal light on the instrument lights up; Multiple system pressure differences: The bus controller has the function of recording the number of pressure difference alarms and the number of low-voltage single box positions corresponding to large pressure differences. When the number of power battery single system pressure difference alarms exceeds the set value, the corresponding power battery fault signal light on the instrument lights up; High-risk system pressure difference: When the number of single power battery system pressure difference alarms exceeds the set value and is identified as a high-risk system pressure difference at the same time, the corresponding power battery fault signal light on the instrument lights up.

2. The method for identifying and handling pressure difference risk of a power battery system for an electric bus according to claim 1, characterized in that: The two discrimination levels of single system voltage difference are 350mV and 500mV respectively.

3. A method for identifying and handling pressure difference risk of a power battery system for an electric bus according to claim 1 or 2, characterized in that: When the charge status indicator light corresponding to the single system pressure difference of the first stage lights up, a text prompt will be displayed on the instrument to indicate that the battery pressure difference is seriously too large and report it to the power battery manufacturer for repair.

4. A method for identifying and handling pressure difference risk of a power battery system for an electric bus according to claim 1 or 2, characterized in that: When the fault signal light corresponding to the second-level single system pressure difference lights up, the instrument will also display a text prompt that the battery pressure difference is seriously too large, report it to the power battery manufacturer for repair and processing, and send a battery serious overcharge alarm signal to the enterprise platform.

5. The method for identifying and handling pressure difference risk of a power battery system for an electric bus according to claim 1, characterized in that: When the fault signal lights corresponding to multiple system pressure differences light up, the instrument will also display a text prompt that the battery pressure difference is seriously too large, report it to the power battery manufacturer for repair and processing, and send a battery serious pressure difference alarm signal to the enterprise platform.

6. A method for identifying and handling pressure difference risk in a power battery system for an electric bus according to claim 1 or 5, characterized in that: The alarm times for multiple system pressure differences and high-risk system pressure differences are both set to 5 times.

7. The method for identifying and handling pressure difference risk of a power battery system for an electric bus according to claim 1, characterized in that: When the fault signal light corresponding to the high-risk system pressure difference lights up, a text prompt will be displayed on the instrument panel indicating that the battery cell is abnormal. The vehicle controller will issue a stop command, the drive power limit signal light will light up, and a rescue request message will be sent to the enterprise platform.

8. The method for identifying and handling pressure difference risk of a power battery system for an electric bus according to claim 1, characterized in that: The identification calculation formula for high-risk system pressure difference is as follows: DV_SOC=[SOC al (1),SOC al (2),...,SOC al (n)] DV_t=[t al (1),t al (2),...,t al (n)], p1=corr(DV_SOC,DV_t), In the formula, the time and SOC value corresponding to the pressure difference exceeding the first threshold are recorded, denoted as tal and SOCal respectively, and the corresponding information of each alarm is recorded in arrays DV_SOC and DV_t respectively. The Pearson coefficient p1 between the two arrays is calculated according to the formula.

9. The method for identifying and handling pressure difference risk of a power battery system for an electric bus according to claim 1, characterized in that: The identification calculation formula for high-risk system pressure difference is as follows: In the formula, the lowest single cell voltage value during the static process after the pressure difference alarm of the battery system is recorded, the corresponding values ​​at the time of the pressure difference alarm are recorded as t(1) and Vmin(1), and the corresponding values ​​at the end of the static state, that is, before the next charge and discharge start, 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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