Power battery pre-undervoltage power limiting method and device, vehicle and storage medium

Abstract

The invention relates to the technical field of vehicle batteries, in particular to a power battery pre-undervoltage power limiting method and device, a vehicle and a storage medium. And determining the current pre-undervoltage grade according to the located voltage interval, determining the power limiting coefficient of the power battery pack according to the pre-undervoltage grade, and limiting the discharge power of the power battery pack. According to the pre-undervoltage power limiting method for the power battery provided by the embodiment of the invention, the voltage interval is identified according to the lowest monomer cell temperature and the lowest monomer cell voltage, and the current pre-undervoltage grade is determined, so that the power limiting coefficient of the power battery pack is determined, and the discharge power of the power battery pack is limited; the problem of vehicle power interruption caused by SOC estimation deviation, overlarge maximum allowable discharge power of the tail end of the power battery and the like of the vehicle is effectively solved, so that the experience feeling of a user is improved.

Description

Technical Field

[0001] This application relates to the technical field of vehicle batteries, and particularly to a method, device, vehicle and storage medium for pre-undervoltage power limitation of power batteries. Background Art

[0002] With the accelerating popularization speed of new energy vehicles, especially plug-in hybrid, range-extended and other new energy vehicles being increasingly recognized by consumers, the penetration rate of hybrid vehicles in the passenger vehicle market is gradually increasing. Hybrid vehicles can, to a certain extent, make up for the problem of insufficient battery life of electric vehicles. Compared with traditional vehicles, they have the advantage of low fuel consumption. The core technology of hybrid vehicles is battery performance, including battery capacity, battery pack layout, etc.

[0003] In related technologies, such as in the patent CN115230533A "A Pre-undervoltage Power Control Strategy and Control System for a Power Battery System", the allowable discharge power of the power battery pack is made to transition smoothly, reducing the risk of over-discharge failure triggered by the minimum cell voltage value, thereby reducing the risk of power loss during driving.

[0004] However, when a hybrid vehicle is in motion and there is a large deviation in the SOC (State Of Charge) of the battery, and the actual battery power has been discharged completely, and the engine has not reached the starting condition, the vehicle will experience a power interruption, thereby reducing the user's driving experience, which urgently needs to be solved. Summary of the Invention

[0005] This application provides a method for pre-undervoltage power limitation of power batteries to improve the problem of vehicle power interruption caused by problems such as SOC estimation deviation and excessive maximum allowable discharge power at the end of the power battery.

[0006] The first aspect of the embodiments of this application provides a method for pre-undervoltage power limitation of power batteries, including the following steps: obtaining the lowest cell temperature and the lowest cell voltage in the power battery pack; if the lowest cell temperature is greater than or equal to a preset temperature, identifying the voltage range where the lowest cell voltage is located, and determining the current pre-undervoltage level according to the voltage range where the lowest cell voltage is located; and determining a power limit coefficient for the power battery pack according to the pre-undervoltage level, and limiting the discharge power of the power battery pack according to the power limit coefficient.

[0007] According to the above technical means, on the premise of not affecting the drivability and power performance of the vehicle, the voltage range is identified according to the obtained lowest single-cell temperature and lowest single-cell voltage in the power battery pack, and the current pre-undervoltage level is determined according to the voltage range. The power limit coefficient of the power battery pack is determined by the pre-undervoltage level, and the discharge power of the power battery pack is limited, effectively optimizing the vehicle power interruption problem caused by problems such as SOC estimation deviation and excessive maximum allowable discharge power at the end of the power battery, thereby improving the user experience.

[0008] Optionally, in some embodiments, the determining the current pre-undervoltage level according to the voltage range where the lowest single-cell voltage is located includes: if the lowest single-cell voltage is less than or equal to a first preset voltage and the lowest single-cell voltage is greater than a second preset voltage, then the current pre-undervoltage level is the first undervoltage level; if the lowest single-cell voltage is less than or equal to the second preset voltage and the lowest single-cell voltage is greater than a third preset voltage, then the current pre-undervoltage level is the second undervoltage level; if the lowest single-cell voltage is less than or equal to the third preset voltage and the lowest single-cell voltage is greater than a fourth preset voltage, then the current pre-undervoltage level is the third undervoltage level, where the fourth preset voltage is the discharge cut-off voltage of the power battery pack; if the lowest single-cell voltage is less than or equal to the fourth preset voltage, then the current pre-undervoltage level is the fourth undervoltage level.

[0009] According to the above technical means, by comparing the lowest single-cell voltage with different preset voltages, the current preset undervoltage level is determined, which is convenient for subsequent different discharge power limitations for the vehicle according to different undervoltage levels.

[0010] Optionally, in some embodiments, the discharge cut-off voltage is determined by the temperature range where the power battery pack is located.

[0011] According to the above technical means, different discharge cut-off voltages are determined according to different temperature ranges where the power battery pack is located, making the setting of the preset voltage more accurate, the discharge efficiency of the battery higher, and thus improving the service life and reliability of the battery.

[0012] Optionally, in some embodiments, determining the power limit coefficient of the power battery pack according to the pre-undervoltage level and limiting the discharge power of the power battery pack according to the power limit coefficient includes: if the pre-undervoltage level is the first undervoltage level, the power limit coefficient is the first preset threshold, and the discharge power of the power battery pack is limited according to the product of the first preset threshold and the target look-up table power; if the pre-undervoltage level is the second undervoltage level, the power limit coefficient is the second preset threshold, and the discharge power of the power battery pack is limited according to the product of the second preset threshold and the target look-up table power, where the second preset threshold is less than the first preset threshold; if the pre-undervoltage level is the third undervoltage level, the power limit coefficient is the third preset threshold, and the discharge power of the power battery pack is limited according to the product of the third preset threshold and the target look-up table power, where the third preset threshold is less than the second preset threshold; if the pre-undervoltage level is the fourth undervoltage level, the discharge power of the power battery pack is limited to 0; where the target look-up table power is determined by the current temperature of the power battery pack and the preset electrical balance point of the power battery pack.

[0013] According to the above technical means, by determining different power limit coefficients of the power battery pack, that is, different preset thresholds, according to different undervoltage levels, and limiting the discharge power of the power battery pack according to the product of different preset thresholds and the target look-up table power, the problem of vehicle power interruption caused by problems such as SOC estimation deviation and excessive maximum allowable discharge power at the end of the power battery is optimized.

[0014] Optionally, in some embodiments, after limiting the discharge power of the power battery pack according to the discharge power limit multiple, it further includes: controlling the vehicle's engine to start to charge the power battery pack, and obtaining the lowest single cell voltage after charging in the power battery pack; judging whether the power battery pack meets the condition for stopping the limitation of the discharge power according to the pre-undervoltage level and the lowest single cell voltage after charging; if the power battery pack meets the condition for stopping the limitation of the discharge power, stop limiting the discharge power of the power battery pack.

[0015] According to the above technical means, after limiting the discharge power of the power battery pack, controlling the vehicle's engine to charge the power battery pack, and judging that if the power battery pack meets the condition for stopping the limitation of the discharge power, stop limiting the discharge power of the power battery pack, thereby giving full play to the discharge capacity of the battery, making the vehicle's power more sufficient, and thus enhancing the user's driving experience.

[0016] Optionally, in some embodiments, determining whether the power battery pack meets the condition for stopping the limited discharge power according to the pre-undervoltage level and the lowest single-cell voltage after charging includes: if the pre-undervoltage level is the first undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the fifth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power; if the pre-undervoltage level is the second undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the sixth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power; if the pre-undervoltage level is the third undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the seventh preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power; if the pre-undervoltage level is the fourth undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the eighth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power.

[0017] According to the above technical means, according to different preset undervoltage levels and the preset voltage range where the lowest single-cell voltage after charging is located, it is determined whether the power battery pack meets the condition for stopping the limited discharge power. By setting the condition for stopping the limited discharge power, on the one hand, if the power battery pack does not meet the condition for stopping the limited discharge power, the discharge power of the battery is continuously limited, which can prevent the battery from over-discharging, thus ensuring the normal and safe use of the battery and extending the service life of the battery. On the other hand, if the power battery pack meets the condition for stopping the limited discharge power, the discharge power of the battery is not limited to give full play to the power capacity of the battery, making the vehicle more powerful and thus improving the user's vehicle use experience.

[0018] Optionally, in some embodiments, after stopping the limitation of the discharge power of the power battery pack, it further includes: if the pre-undervoltage level is the first undervoltage level, the discharge power of the power battery pack is restored to the product of the fourth preset threshold and the target look-up table power; if the pre-undervoltage level is the second undervoltage level, the discharge power of the power battery pack is restored to the product of the fifth preset threshold and the target look-up table power; if the pre-undervoltage level is the third undervoltage level, the discharge power of the power battery pack is restored to the product of the sixth preset threshold and the target look-up table power; if the pre-undervoltage level is the fourth undervoltage level, the discharge power of the power battery pack is restored to the preset discharge power.

[0019] According to the above technical means, according to different preset under-voltage levels, the power battery looks up the table based on temperature and SOC power, and restores the discharge power of the power battery pack to the product of different preset thresholds and the target lookup power or restores it to the preset discharge power, so that the allowable discharge power of the power battery pack transitions smoothly, thereby fully exerting the discharge power capacity of the battery, making the vehicle more powerful and providing a better vehicle use experience for users.

[0020] The second aspect of the embodiments of the present application provides a power battery pre-under-voltage power limit device, including: an acquisition module, configured to acquire the lowest single-cell temperature and the lowest single-cell voltage in the power battery pack; an identification module, configured to, if the lowest single-cell temperature is greater than or equal to a preset temperature, identify the voltage range where the lowest single-cell voltage is located, and determine the current pre-under-voltage level according to the voltage range where the lowest single-cell voltage is located; and a limit module, configured to determine the power limit coefficient of the power battery pack according to the pre-under-voltage level, and limit the discharge power of the power battery pack according to the power limit coefficient.

[0021] Optionally, in some embodiments, the identification module is specifically configured to: if the lowest single-cell voltage is less than or equal to a first preset voltage and the lowest single-cell voltage is greater than a second preset voltage, the current pre-under-voltage level is the first under-voltage level; if the lowest single-cell voltage is less than or equal to the second preset voltage and the lowest single-cell voltage is greater than a third preset voltage, the current pre-under-voltage level is the second under-voltage level; if the lowest single-cell voltage is less than or equal to the third preset voltage and the lowest single-cell voltage is greater than a fourth preset voltage, the current pre-under-voltage level is the third under-voltage level, where the fourth preset voltage is the discharge cut-off voltage of the power battery pack; if the lowest single-cell voltage is less than or equal to the fourth preset voltage, the current pre-under-voltage level is the fourth under-voltage level.

[0022] Optionally, in some embodiments, the discharge cut-off voltage is determined by the temperature range where the power battery pack is located.

[0023] Optionally, in some embodiments, the limiting module is specifically configured to: if the pre-undervoltage level is the first undervoltage level, the power limiting coefficient is a first preset threshold, and the discharge power of the power battery pack is limited according to the product of the first preset threshold and the target look-up table power; if the pre-undervoltage level is the second undervoltage level, the power limiting coefficient is a second preset threshold, and the discharge power of the power battery pack is limited according to the product of the second preset threshold and the target look-up table power, where the second preset threshold is less than the first preset threshold; if the pre-undervoltage level is the third undervoltage level, the power limiting coefficient is a third preset threshold, and the discharge power of the power battery pack is limited according to the product of the third preset threshold and the target look-up table power, where the third preset threshold is less than the second preset threshold; if the pre-undervoltage level is the fourth undervoltage level, the discharge power of the power battery pack is limited to 0; where the target look-up table power is determined by the current temperature of the power battery pack and the preset electrical balance point of the power battery pack.

[0024] Optionally, in some embodiments, after limiting the discharge power of the power battery pack according to the discharge power limiting multiple, the limiting module is further configured to: control the vehicle's engine to start to charge the power battery pack, and obtain the lowest single cell voltage after charging in the power battery pack; determine whether the power battery pack meets the condition for stopping limiting the discharge power according to the pre-undervoltage level and the lowest single cell voltage after charging; if the power battery pack meets the condition for stopping limiting the discharge power, stop limiting the discharge power of the power battery pack.

[0025] Optionally, in some embodiments, the limiting module is further configured to: if the pre-undervoltage level is the first undervoltage level and the lowest single cell voltage after charging is greater than or equal to a fifth preset voltage, determine that the power battery pack meets the condition for stopping limiting the discharge power; if the pre-undervoltage level is the second undervoltage level and the lowest single cell voltage after charging is greater than or equal to a sixth preset voltage, determine that the power battery pack meets the condition for stopping limiting the discharge power; if the pre-undervoltage level is the third undervoltage level and the lowest single cell voltage after charging is greater than or equal to a seventh preset voltage, determine that the power battery pack meets the condition for stopping limiting the discharge power; if the pre-undervoltage level is the fourth undervoltage level and the lowest single cell voltage after charging is greater than or equal to an eighth preset voltage, determine that the power battery pack meets the condition for stopping limiting the discharge power.

[0026] Optionally, in some embodiments, after stopping limiting the discharge power of the power battery pack, the limiting module is further configured to: if the pre-undervoltage level is the first undervoltage level, restore the discharge power of the power battery pack to the product of a fourth preset threshold and the target look-up table power; if the pre-undervoltage level is the second undervoltage level, restore the discharge power of the power battery pack to the product of a fifth preset threshold and the target look-up table power; if the pre-undervoltage level is the third undervoltage level, restore the discharge power of the power battery pack to the product of a sixth preset threshold and the target look-up table power; if the pre-undervoltage level is the fourth undervoltage level, restore the discharge power of the power battery pack to a preset discharge power.

[0027] An embodiment of the third aspect of the present application provides a vehicle, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the program to implement the power battery pre-undervoltage power limiting method as described in the above embodiments.

[0028] An embodiment of the fourth aspect of the present application provides a computer-readable storage medium, on which a computer program is stored, and the program is executed by a processor to implement the power battery pre-undervoltage power limiting method as described in the above embodiments.

[0029] Advantages of the present invention:

[0030] (1) By limiting the power in advance at the end of discharge, the present application optimizes the problem of vehicle power interruption caused by the rapid drop of the single-cell voltage to the cut-off voltage due to excessive power at the end of discharge.

[0031] (2) By limiting the power in advance at the end of discharge, the present application further optimizes the problem of vehicle power interruption caused by excessive deviation in battery SOC estimation.

[0032] (3) The present application can prevent the risk of over-discharge of the power battery pack.

[0033] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flowchart of a method for limiting the power of a power battery with pre-undervoltage according to the present invention;

[0035] Figure 2 is a schematic diagram of the charge and discharge voltage range of a power lithium-ion battery according to an embodiment of the present invention;

[0036] Figure 3Schematic diagram of the SOC usage range of a hybrid vehicle according to an embodiment of the present invention;

[0037] Figure 4 Block diagram of a power battery pre-undervoltage power limit device according to an embodiment of the present invention;

[0038] Figure 5 Block diagram of a vehicle according to an embodiment of the present invention.

[0039] Among them, 10 - power battery pre-undervoltage power limit device; 100 - acquisition module, 200 - identification module, 300 - limit module; 501 - memory, 502 - processor, 503 - communication interface. Detailed implementation manners

[0040] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and should not be construed as a limitation of the present application.

[0041] The power battery pre-undervoltage power limit method of the embodiments of the present application will be described below with reference to the accompanying drawings. In view of the vehicle power interruption problems caused by issues such as SOC estimation deviation and excessive maximum allowable discharge power at the end of the power battery in the above-mentioned background technology, the present application provides a power battery pre-undervoltage power limit method. In this method, the voltage range where the lowest single-cell voltage in the power battery pack is located is identified based on the obtained lowest single-cell temperature and lowest single-cell voltage in the power battery pack, and the current pre-undervoltage level is determined. The power limit coefficient of the power battery pack is determined by the pre-undervoltage level, and the discharge power of the power battery pack is limited. According to the power battery pre-undervoltage power limit method of the embodiments of the present application, the vehicle discharge power is limited in advance through different pre-undervoltage levels, effectively optimizing the vehicle power interruption problems caused by issues such as SOC estimation deviation and excessive maximum allowable discharge power at the end of the power battery, thereby improving the user experience.

[0042] Specifically, Figure 1 It is a flowchart of a power battery pre-undervoltage power limit method provided by an embodiment of the present application.

[0043] As Figure 1 shown, the power battery pre-undervoltage power limit method includes the following steps:

[0044] In step S101, the lowest single-cell temperature and the lowest single-cell voltage in the power battery pack are acquired.

[0045] Specifically, in the embodiments of the present application, the lowest single-cell temperature in the power battery pack can be obtained through a temperature sensor, and the lowest single-cell voltage in the power battery pack can be obtained through a voltage sensor. It should be noted that obtaining the lowest single-cell temperature in the power battery pack through the temperature sensor and obtaining the lowest single-cell voltage in the power battery pack through the voltage sensor are only exemplary and do not limit the present application. The lowest single-cell temperature can also be obtained through a thermistor, and the lowest single-cell voltage can be obtained through a voltmeter. Those skilled in the art can also adopt other methods to obtain the lowest single-cell temperature and the lowest single-cell voltage in the power battery pack according to the actual situation. To avoid redundancy, no detailed description will be given here.

[0046] In step S102, if the lowest single-cell temperature is greater than or equal to the preset temperature, identify the voltage range where the lowest single-cell voltage is located, and determine the current pre-undervoltage level according to the voltage range where the lowest single-cell voltage is located.

[0047] Among them, the preset temperature can be a temperature preset by those skilled in the art, a temperature obtained through a limited number of experiments, or a temperature obtained through a limited number of computer simulations, and no specific limitation is made here. The current pre-undervoltage level can be an undervoltage level preset by those skilled in the art, an undervoltage level obtained through a limited number of experiments, or an undervoltage level obtained through a limited number of computer simulations, and no specific limitation is made here.

[0048] It should be noted that the power battery belongs to a lithium-ion battery. During the charge and discharge process, lithium ions move between the positive and negative electrodes, generating electrical energy and providing power. As Figure 2 shown, the voltage platform area of the power lithium-ion battery is Vmin to Vmax, and the charge and discharge are carried out within this range. Therefore, in the embodiments of the present application, different levels of preset voltage ranges can be divided based on this charge and discharge range, and the current pre-undervoltage level can be determined according to the voltage range where the lowest single-cell voltage is located.

[0049] Optionally, in some embodiments, determining the current pre-undervoltage level according to the voltage range where the lowest single-cell voltage is located includes: if the lowest single-cell voltage is less than or equal to the first preset voltage and the lowest single-cell voltage is greater than the second preset voltage, the current pre-undervoltage level is the first undervoltage level; if the lowest single-cell voltage is less than or equal to the second preset voltage and the lowest single-cell voltage is greater than the third preset voltage, the current pre-undervoltage level is the second undervoltage level; if the lowest single-cell voltage is less than or equal to the third preset voltage and the lowest single-cell voltage is greater than the fourth preset voltage, the current pre-undervoltage level is the third undervoltage level, where the fourth preset voltage is the discharge cut-off voltage of the power battery pack; if the lowest single-cell voltage is less than or equal to the fourth preset voltage, the current pre-undervoltage level is the fourth undervoltage level.

[0050] Optionally, in some embodiments, the discharge cut-off voltage is determined by the temperature range in which the power battery pack is located.

[0051] Specifically, the voltage range where the lowest single cell voltage is located is compared with different preset voltages to determine the current preset undervoltage level, which facilitates subsequent adoption of different discharge power limits for the vehicle according to different undervoltage levels.

[0052] For example, let the first preset voltage be a, the second preset voltage be b, the third preset voltage be c, and the fourth preset voltage be d. When the lowest single cell voltage is greater than b and less than or equal to a, it is determined that the current preset undervoltage level is the first undervoltage level; when the lowest single cell voltage is greater than c and less than or equal to b, it is determined that the current preset undervoltage level is the second undervoltage level; when the lowest single cell voltage is greater than d and less than or equal to c, it is determined that the current preset undervoltage level is the third undervoltage level; when the lowest single cell voltage is less than or equal to d, it is determined that the current preset undervoltage level is the fourth undervoltage level.

[0053] In step S103, the power limit coefficient of the power battery pack is determined according to the preset undervoltage level, and the discharge power of the power battery pack is limited according to the power limit coefficient.

[0054] Optionally, in some embodiments, determining the power limit coefficient of the power battery pack according to the preset undervoltage level and limiting the discharge power of the power battery pack according to the power limit coefficient includes: if the preset undervoltage level is the first undervoltage level, the power limit coefficient is the first preset threshold, and the discharge power of the power battery pack is limited according to the product of the first preset threshold and the target look-up table power; if the preset undervoltage level is the second undervoltage level, the power limit coefficient is the second preset threshold, and the discharge power of the power battery pack is limited according to the product of the second preset threshold and the target look-up table power, where the second preset threshold is less than the first preset threshold; if the preset undervoltage level is the third undervoltage level, the power limit coefficient is the third preset threshold, and the discharge power of the power battery pack is limited according to the product of the third preset threshold and the target look-up table power, where the third preset threshold is less than the second preset threshold; if the preset undervoltage level is the fourth undervoltage level, the discharge power of the power battery pack is limited to 0; where the target look-up table power is determined by the current temperature of the power battery pack and the preset electrical balance point of the power battery pack.

[0055] Among them, the power limit coefficient is a different preset threshold corresponding to different undervoltage levels. It can be a threshold preset by those skilled in the art, a threshold obtained through a finite number of experiments, or a threshold obtained through a finite number of computer simulations. Specific limitations are not made here. The preset electrical balance point can be an electrical balance point preset by those skilled in the art, an electrical balance point obtained through a finite number of experiments, or an electrical balance point obtained through a finite number of computer simulations. Specific limitations are not made here.

[0056] It should be noted that, as Figure 3 shown, the single-cell voltage is in the SOC usage range of SOCmin to SOCmax calculated according to the hybrid vehicle's SOC. When the battery SOC of the hybrid vehicle is relatively low and the battery output power cannot meet the normal driving requirements at this time, the engine provides power, and the SOC point at this time is called the electrical balance point.

[0057] Specifically, by determining different power limit coefficients of the power battery pack according to different undervoltage levels, that is, different preset thresholds, and determining the target look-up table power from the current temperature of the power battery pack and the preset electrical balance point of the power battery pack, the discharge power of the power battery pack is restricted according to the product of different preset thresholds and the target look-up table power.

[0058] For example, let the target look-up table power be P. When the pre-undervoltage level is the first undervoltage level, the power limit coefficient is A, and the discharge power of the power battery pack is restricted by A*P times; when the pre-undervoltage level is the second undervoltage level, the power limit coefficient is B, and the discharge power of the power battery pack is restricted by B*P times; when the pre-undervoltage level is the third undervoltage level, the power limit coefficient is C, and the discharge power of the power battery pack is restricted by C*P times, where C < B < A; when the pre-undervoltage level is the fourth undervoltage level, the discharge power of the power battery pack is restricted to 0, that is, the power battery pack does not discharge, and the engine provides power to ensure that the vehicle power is not interrupted.

[0059] Optionally, in some embodiments, after restricting the discharge power of the power battery pack according to the discharge power restriction multiple, it further includes: controlling the vehicle's engine to start to charge the power battery pack, and obtaining the lowest single-cell voltage in the power battery pack after charging; judging whether the power battery pack meets the condition for stopping restricting the discharge power according to the pre-undervoltage level and the lowest single-cell voltage after charging; if the power battery pack meets the condition for stopping restricting the discharge power, stop restricting the discharge power of the power battery pack.

[0060] Among them, during the normal driving process of a hybrid vehicle, the whole vehicle will set an electrical balance point according to the State of Charge (SOC) of the power battery. When the electrical balance point condition is reached, the engine provides kinetic energy. On the one hand, it can ensure power and supply electrical energy, and on the other hand, it can charge the battery, thus achieving a charging effect. The following are two specific situations:

[0061] During the vehicle driving process, when the SOC of the power battery is falsely high and the voltage of a single battery cell triggers the pre-undervoltage condition, the output power at this time does not meet the driving requirements, and the engine starts to provide kinetic energy, so that the power battery does not report a fault and the power of the whole vehicle is not interrupted during the whole process.

[0062] During the vehicle driving process, under normal conditions of low SOC of the power battery, when the electrical balance point is reached, in the case of rapid acceleration and rapid deceleration, the power battery discharges under the action of a large current, and the battery voltage drops to the discharge cut-off voltage, triggering the pre-undervoltage strategy to limit the discharge power. At this time, the engine provides kinetic energy, so as to ensure that the power battery does not report a fault and the power of the whole vehicle is not interrupted during the whole process.

[0063] Specifically, after restricting the discharge power of the power battery pack, control the vehicle's engine to charge the power battery pack, and judge that if the power battery pack meets the condition for stopping restricting the discharge power, then stop restricting the discharge power of the power battery pack, thereby reducing the risk of power interruption during the driving process.

[0064] Optionally, in some embodiments, judging whether the power battery pack meets the condition for stopping restricting the discharge power according to the pre-undervoltage level and the lowest voltage of a single battery cell after charging includes: if the pre-undervoltage level is the first undervoltage level and the lowest voltage of a single battery cell after charging is greater than or equal to the fifth preset voltage, it is determined that the power battery pack meets the condition for stopping restricting the discharge power; if the pre-undervoltage level is the second undervoltage level and the lowest voltage of a single battery cell after charging is greater than or equal to the sixth preset voltage, it is determined that the power battery pack meets the condition for stopping restricting the discharge power; if the pre-undervoltage level is the third undervoltage level and the lowest voltage of a single battery cell after charging is greater than or equal to the seventh preset voltage, it is determined that the power battery pack meets the condition for stopping restricting the discharge power; if the pre-undervoltage level is the fourth undervoltage level and the lowest voltage of a single battery cell after charging is greater than or equal to the eighth preset voltage, it is determined that the power battery pack meets the condition for stopping restricting the discharge power.

[0065] Among them, the preset voltage can be a voltage preset by those skilled in the art, a voltage obtained through a limited number of experiments, or a voltage obtained through a limited number of computer simulations, and no specific limitation is made here.

[0066] Specifically, according to different preset undervoltage levels and the preset voltage range where the lowest voltage of a single battery cell after charging is located, it is determined whether the power battery pack meets the condition for stopping restricting the discharge power, so as to fully exert the power capacity of the battery.

[0067] Optionally, in some embodiments, after stopping the limitation of the discharge power of the power battery pack, it further includes: if the pre-undervoltage level is the first undervoltage level, restoring the discharge power of the power battery pack to the product of a fourth preset threshold and the target look-up table power; if the pre-undervoltage level is the second undervoltage level, restoring the discharge power of the power battery pack to the product of a fifth preset threshold and the target look-up table power; if the pre-undervoltage level is the third undervoltage level, restoring the discharge power of the power battery pack to the product of a sixth preset threshold and the target look-up table power; if the pre-undervoltage level is the fourth undervoltage level, restoring the discharge power of the power battery pack to the preset discharge power.

[0068] Wherein, the preset discharge power can be the discharge power preset by those skilled in the art, can be the discharge power obtained through a finite number of experiments, or can be the discharge power obtained through a finite number of computer simulations, and is not specifically limited herein.

[0069] Specifically, after stopping the limitation of the discharge power of the power battery pack, according to different preset undervoltage levels, the discharge power of the power battery pack is restored to the product of different preset thresholds and the target look-up table power or restored to the preset discharge power, so that the allowable discharge power of the power battery pack transitions smoothly, and further makes the vehicle have more power, thereby enhancing the user experience.

[0070] To facilitate those skilled in the art to more clearly and intuitively understand the power battery pre-undervoltage power limit method of the embodiments of the present application, the following will be described in detail with reference to Table 1.

[0071] As shown in Table 1, the dynamic electrical balance point SOC = xx%, N1 is the first undervoltage level, N2 is the second undervoltage level, N3 is the third undervoltage level, N4 is the fourth undervoltage level, V0 is the discharge cut-off voltage, V1, V2, V3 are the discharge cut-off voltages corresponding to different battery assembly temperature usage ranges, T1, T2, T3 are the temperature usage range thresholds of the power battery cells, and the specific values are as follows: when Tmax > T1 °C, V0 = V1; when T2 °C < Tmax ≤ T1 °C, V0 = V2; when T3 °C < Tmax ≤ T2 °C, V0 = V3; when Tmax ≤ T3 °C, V0 = V4, A is the discharge power limit coefficient at the first undervoltage level, B is the discharge power limit coefficient at the second undervoltage level, C is the discharge power limit coefficient at the third undervoltage level, D is the discharge power recovery coefficient at the first undervoltage level, E is the discharge power recovery coefficient at the second undervoltage level, F is the discharge power recovery coefficient at the third undervoltage level, and t is the monomer voltage holding time.

[0072] Specifically, during the vehicle discharging process, when the lowest single-cell temperature T0 of the power battery is greater than Tmax and the lowest single-cell voltage of the battery is Vmin ≤ (V0 + a), during the continuous discharging process of the battery for t seconds, the N1-level pre-undervoltage is triggered. At this time, the power of the power battery is obtained by looking up the table according to the temperature and SOC, and the power reduction limit is limited by P*A times. When Vmin ≥ (V0 + d), the power is restored to D times.

[0073] During the vehicle discharging process, when the lowest single-cell temperature T0 of the power battery is greater than Tmax and the lowest single-cell voltage of the battery is Vmin ≤ (V0 + b), during the continuous discharging process of the battery for t seconds, the N2-level pre-undervoltage is triggered. At this time, the power of the power battery is obtained by looking up the table according to the temperature and SOC, and the power reduction limit is limited by P*B times. When Vmin ≥ (V0 + e), the power is restored to E times.

[0074] During the vehicle discharging process, when the lowest single-cell temperature T0 of the power battery is greater than Tmax and the lowest single-cell voltage of the battery is Vmin ≤ (V0 + c), during the continuous discharging process of the battery for t seconds, the N3-level pre-undervoltage is triggered. At this time, the power of the power battery is obtained by looking up the table according to the temperature and SOC, and the power reduction limit is limited by P*C times. When Vmin ≥ (V0 + f), the power is restored to F times.

[0075] During the vehicle discharging process, when the lowest single-cell temperature T0 of the power battery is greater than Tmax and the lowest single-cell voltage of the battery is Vmin ≤ V0, during the continuous discharging process of the battery for t seconds, the N4-level pre-undervoltage is triggered. At this time, the power of the power battery is obtained by looking up the table according to the temperature and SOC, and the power reduction limit is limited to 0. When Vmin ≥ (V0 + w), the power is restored to x kW.

[0076] In summary, according to the power battery, when the lowest single-cell voltage is Vmin ≤ V0, 4 levels of pre-undervoltage are triggered. Based on different temperatures, the voltage threshold of V0 is different. According to the different degrees of voltage drop, the levels of triggered pre-undervoltage are also different, and the resulting consequences are also different. Therefore, the recovery conditions are also different.

[0077] Table 1

[0078]

[0079]

[0080] According to the power battery pre-undervoltage power limit method of the embodiments of the present application, the voltage range is identified based on the obtained lowest single-cell temperature and the lowest single-cell voltage in the power battery pack, and the current pre-undervoltage level is determined according to the voltage range. The power limit coefficient of the power battery pack is determined by the pre-undervoltage level, and the discharge power of the power battery pack is limited. Thus, by identifying the voltage range based on the lowest single-cell temperature and the lowest single-cell voltage and determining the current pre-undervoltage level, and then determining the power limit coefficient of the power battery pack and limiting the discharge power of the power battery pack, the problem of vehicle power interruption caused by problems such as SOC estimation deviation and excessive maximum allowable discharge power at the end of the power battery is effectively optimized, thereby improving the user experience.

[0081] Next, a power battery pre-undervoltage power limit device according to an embodiment of the present application will be described with reference to the accompanying drawings.

[0082] Figure 4 It is a block diagram of the power battery pre-undervoltage power limit device of the present invention.

[0083] As Figure 4 shown, the power battery pre-undervoltage power limit device 10 includes: an acquisition module 100, an identification module 200, and a limit module 300.

[0084] Among them, the acquisition module 100 is used to acquire the lowest single-cell temperature and the lowest single-cell voltage in the power battery pack;

[0085] The identification module 200 is used to identify the voltage range of the lowest single-cell voltage if the lowest single-cell temperature is greater than or equal to a preset temperature, and determine the current pre-undervoltage level according to the voltage range of the lowest single-cell voltage; and

[0086] The limit module 300 is used to determine the power limit coefficient of the power battery pack according to the pre-undervoltage level, and limit the discharge power of the power battery pack according to the power limit coefficient.

[0087] Optionally, in some embodiments, the identification module 200 includes:

[0088] If the lowest single-cell voltage is less than or equal to a first preset voltage and the lowest single-cell voltage is greater than a second preset voltage, the current pre-undervoltage level is the first undervoltage level;

[0089] If the lowest single-cell voltage is less than or equal to the second preset voltage and the lowest single-cell voltage is greater than a third preset voltage, the current pre-undervoltage level is the second undervoltage level;

[0090] If the voltage of the lowest single battery cell is less than or equal to the third preset voltage and greater than the fourth preset voltage, the current pre-undervoltage level is the third undervoltage level, where the fourth preset voltage is the discharge cut-off voltage of the power battery pack;

[0091] If the voltage of the lowest single battery cell is less than or equal to the fourth preset voltage, the current pre-undervoltage level is the fourth undervoltage level.

[0092] Optionally, in some embodiments, the discharge cut-off voltage is determined by the temperature range in which the power battery pack is located.

[0093] Optionally, in some embodiments, the limiting module 300 includes:

[0094] If the pre-undervoltage level is the first undervoltage level, the power limiting coefficient is the first preset threshold, and the discharge power of the power battery pack is limited according to the product of the first preset threshold and the target look-up table power;

[0095] If the pre-undervoltage level is the second undervoltage level, the power limiting coefficient is the second preset threshold, and the discharge power of the power battery pack is limited according to the product of the second preset threshold and the target look-up table power, where the second preset threshold is less than the first preset threshold;

[0096] If the pre-undervoltage level is the third undervoltage level, the power limiting coefficient is the third preset threshold, and the discharge power of the power battery pack is limited according to the product of the third preset threshold and the target look-up table power, where the third preset threshold is less than the second preset threshold;

[0097] If the pre-undervoltage level is the fourth undervoltage level, the discharge power of the power battery pack is limited to 0;

[0098] Wherein, the target look-up table power is determined by the current temperature of the power battery pack and the preset electrical balance point of the power battery pack.

[0099] Optionally, in some embodiments, after limiting the discharge power of the power battery pack according to the discharge power limiting multiple, the limiting module 300 further includes:

[0100] Controlling the vehicle's engine to start charging the power battery pack and obtaining the voltage of the lowest single battery cell after charging in the power battery pack;

[0101] Judging whether the power battery pack meets the condition for stopping limiting the discharge power according to the pre-undervoltage level and the voltage of the lowest single battery cell after charging;

[0102] If the power battery pack meets the condition for stopping limiting the discharge power, stop limiting the discharge power of the power battery pack.

[0103] Optionally, in some embodiments, it is determined whether the power battery pack meets the condition for stopping the limited discharge power according to the pre-undervoltage level and the lowest single-cell voltage after charging. The limiting module 300 includes:

[0104] If the pre-undervoltage level is the first undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the fifth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power;

[0105] If the pre-undervoltage level is the second undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the sixth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power;

[0106] If the pre-undervoltage level is the third undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the seventh preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power;

[0107] If the pre-undervoltage level is the fourth undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the eighth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power.

[0108] Optionally, in some embodiments, after stopping the limitation of the discharge power of the power battery pack, the limiting module 300 further includes:

[0109] If the pre-undervoltage level is the first undervoltage level, the discharge power of the power battery pack is restored to the product of the fourth preset threshold and the target look-up table power; if the pre-undervoltage level is the second undervoltage level, the discharge power of the power battery pack is restored to the product of the fifth preset threshold and the target look-up table power;

[0110] If the pre-undervoltage level is the third undervoltage level, the discharge power of the power battery pack is restored to the product of the sixth preset threshold and the target look-up table power;

[0111] If the pre-undervoltage level is the fourth undervoltage level, the discharge power of the power battery pack is restored to the preset discharge power.

[0112] It should be noted that the foregoing explanation of the embodiments of the power battery pre-undervoltage power limitation method is also applicable to the power battery pre-undervoltage power limitation device of this embodiment, and will not be elaborated here.

[0113] The power battery pre-undervoltage power limit device according to the embodiment of the present application identifies the voltage range according to the obtained lowest single-cell temperature and lowest single-cell voltage in the power battery pack, determines the current pre-undervoltage level according to the voltage range, determines the power limit coefficient of the power battery pack from the pre-undervoltage level, and limits the discharge power of the power battery pack. Thus, by identifying the voltage range according to the lowest single-cell temperature and lowest single-cell voltage and determining the current pre-undervoltage level, and then determining the power limit coefficient of the power battery pack and limiting the discharge power of the power battery pack, the problem of vehicle power interruption caused by problems such as SOC estimation deviation and excessive maximum allowable discharge power at the end of the power battery is effectively optimized, thereby improving the user experience.

[0114] Figure 5 The structure diagram of the vehicle provided in this embodiment is shown. The vehicle may include:

[0115] A memory 501, a processor 502, and a computer program stored on the memory 501 and executable on the processor 502.

[0116] When the processor 502 executes the program, it implements the power battery pre-undervoltage power limit method provided in the above embodiment.

[0117] Further, the vehicle further includes:

[0118] A communication interface 503 for communication between the memory 501 and the processor 502.

[0119] The memory 501 is used to store a computer program executable on the processor 502.

[0120] The memory 501 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0121] If the memory 501, the processor 502, and the communication interface 503 are implemented independently, the communication interface 503, the memory 501, and the processor 502 can be interconnected through a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5It is represented by only a thick line in the figure, but it does not mean that there is only one bus or one type of bus.

[0122] Optionally, in a specific implementation, if the memory 501, the processor 502, and the communication interface 503 are integrated on a single chip, the memory 501, the processor 502, and the communication interface 503 can communicate with each other through an internal interface.

[0123] The processor 502 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement this embodiment.

[0124] This embodiment also provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the above-mentioned power battery pre-undervoltage power limit method is implemented.

[0125] In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0126] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0127] Any process or method description depicted in the flowchart or otherwise described herein may be understood to represent a module, segment, or portion of code including one or N executable instructions for implementing a customized logical function or process. The scope of the preferred embodiments of the present application includes additional implementations, where functions may be performed in a substantially simultaneous manner or in a reverse order according to the functions involved, rather than in the order shown or discussed. This should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0128] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with suitable combinational logic gate circuits, programmable gate arrays, field-programmable gate arrays, and the like.

[0129] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried out in implementing the methods of the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0130] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A method for pre-under-voltage power limitation of a power battery, comprising the following steps: Obtain the lowest single-cell temperature and the lowest single-cell voltage within the power battery pack; If the lowest single-cell temperature is greater than or equal to a preset temperature, identify the voltage range where the lowest single-cell voltage is located, and determine the current pre-under-voltage level according to the voltage range where the lowest single-cell voltage is located; And Determine the power limitation coefficient of the power battery pack according to the pre-under-voltage level, and limit the discharge power of the power battery pack according to the power limitation coefficient.

2. The method according to claim 1, wherein The step of determining the current pre-under-voltage level according to the voltage range where the lowest single-cell voltage is located includes: If the lowest single-cell voltage is less than or equal to a first preset voltage and the lowest single-cell voltage is greater than a second preset voltage, the current pre-under-voltage level is the first under-voltage level; If the lowest single-cell voltage is less than or equal to the second preset voltage and the lowest single-cell voltage is greater than a third preset voltage, the current pre-under-voltage level is the second under-voltage level; If the lowest single-cell voltage is less than or equal to the third preset voltage and the lowest single-cell voltage is greater than a fourth preset voltage, the current pre-under-voltage level is the third under-voltage level, where the fourth preset voltage is the discharge cut-off voltage of the power battery pack; If the lowest single-cell voltage is less than or equal to the fourth preset voltage, the current pre-under-voltage level is the fourth under-voltage level.

3. The method according to claim 2, wherein The discharge cut-off voltage is determined by the temperature range where the power battery pack is located.

4. The method according to claim 2, wherein The step of determining the power limitation coefficient of the power battery pack according to the pre-under-voltage level, and limiting the discharge power of the power battery pack according to the power limitation coefficient includes: If the pre-under-voltage level is the first under-voltage level, the power limitation coefficient is a first preset threshold, and the discharge power of the power battery pack is limited according to the product of the first preset threshold and the target look-up table power; If the pre-under-voltage level is the second under-voltage level, the power limitation coefficient is a second preset threshold, and the discharge power of the power battery pack is limited according to the product of the second preset threshold and the target look-up table power, where the second preset threshold is less than the first preset threshold; If the pre-under-voltage level is the third under-voltage level, the power limitation coefficient is a third preset threshold, and the discharge power of the power battery pack is limited according to the product of the third preset threshold and the target look-up table power, where the third preset threshold is less than the second preset threshold; If the pre-under-voltage level is the fourth under-voltage level, limit the discharge power of the power battery pack to 0; Wherein, the target look-up table power is determined by the current temperature of the power battery pack and the preset electrical balance point of the power battery pack.

5. The method according to claim 4, wherein After limiting the discharge power of the power battery pack according to the discharge power limitation multiple, it further includes: Control the vehicle's engine to start to charge the power battery pack, and obtain the lowest single-cell voltage after charging within the power battery pack; Determine whether the power battery pack meets the condition for stopping the limited discharge power according to the pre-undervoltage level and the lowest single-cell voltage after charging; If the power battery pack meets the condition for stopping the limited discharge power, stop limiting the discharge power of the power battery pack.

6. The method according to claim 5, wherein The determination of whether the power battery pack meets the condition for stopping the limited discharge power according to the pre-undervoltage level and the lowest single-cell voltage after charging includes: If the pre-undervoltage level is the first undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the fifth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power; If the pre-undervoltage level is the second undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the sixth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power; If the pre-undervoltage level is the third undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the seventh preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power; If the pre-undervoltage level is the fourth undervoltage level and the lowest single-cell voltage after charging is greater than or equal to the eighth preset voltage, it is determined that the power battery pack meets the condition for stopping the limited discharge power.

7. The method according to claim 6, wherein After stopping the limitation of the discharge power of the power battery pack, it further includes: If the pre-undervoltage level is the first undervoltage level, restore the discharge power of the power battery pack to the product of the fourth preset threshold and the target look-up table power; if the pre-undervoltage level is the second undervoltage level, restore the discharge power of the power battery pack to the product of the fifth preset threshold and the target look-up table power; If the pre-undervoltage level is the third undervoltage level, restore the discharge power of the power battery pack to the product of the sixth preset threshold and the target look-up table power; If the pre-undervoltage level is the fourth undervoltage level, restore the discharge power of the power battery pack to the preset discharge power.

8. A pre-under-voltage and power limit device for a power battery, characterized in that, It includes: An acquisition module for acquiring the lowest single-cell temperature and the lowest single-cell voltage in the power battery pack; An identification module for, if the lowest single-cell temperature is greater than or equal to the preset temperature, identifying the voltage range where the lowest single-cell voltage is located and determining the current pre-undervoltage level according to the voltage range where the lowest single-cell voltage is located; And A limitation module for determining the power limitation coefficient of the power battery pack according to the pre-undervoltage level and limiting the discharge power of the power battery pack according to the power limitation coefficient.

9. A vehicle, characterized in that, It includes: A memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the program to implement the power battery pre-undervoltage power limitation method according to any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to be used to implement the power battery pre-undervoltage power limitation method according to any one of claims 1-7.

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