Method for charging a power battery and battery management system

Abstract

The present invention provides a method for charging a power battery and a battery management system. The method comprises: obtaining the potential of the negative electrode of the power battery during charging; and controlling the power battery to discharge when the difference between the negative electrode potential and a preset potential is less than or equal to a safety threshold. The method and battery management system of the present invention can improve the safety performance of the power battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for charging a power battery and a battery management system. Background Art

[0002] With the development of the times, electric vehicles have huge market prospects due to their high environmental protection, low noise, low cost of use and other advantages. They can effectively promote energy conservation and emission reduction, which is beneficial to the development and progress of society.

[0003] For electric vehicles and related sectors, battery technology is a crucial factor in their development. Battery safety, in particular, impacts the development and application of battery-related products and influences public acceptance of electric vehicles. Therefore, improving the safety performance of power batteries remains a technical challenge to be solved. Summary of the Invention

[0004] The embodiments of the present application provide a method for charging a power battery and a battery management system, which can improve the safety performance of the power battery.

[0005] In a first aspect, a method for charging a power battery is provided, comprising: obtaining the negative electrode potential of the power battery during the charging process; and controlling the power battery to discharge when the difference between the negative electrode potential and a preset potential is less than or equal to a safety threshold.

[0006] By setting a safety threshold, the BMS controls the power battery to discharge when the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold. That is to say, the BMS controls the power battery to discharge before the negative electrode potential reaches the preset potential, which can avoid the precipitation of lithium metal on the negative electrode surface, thereby improving the safety performance of the power battery.

[0007] In one possible implementation, when the difference between the negative electrode potential and the preset potential is less than or equal to a safety threshold, the power battery is controlled to discharge, including: when the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, sending first charging request information to the charging pile, the first charging request information being used to request a charging current of 0; and when the actual charging current of the power battery collected is less than or equal to the current threshold, controlling the power battery to discharge.

[0008] When the actual charging current of the power battery is less than or equal to the current threshold, the power battery is controlled to discharge, which is beneficial to improving the inhibitory effect of the power battery discharge on the lithium deposition of the battery.

[0009] In a possible implementation, the method further includes: controlling the power battery to stop discharging when the duration for which the first charging request information has been sent is greater than or equal to the first time interval.

[0010] In a possible implementation, the method further includes: controlling the power battery to stop discharging when the duration of controlling the power battery to discharge is greater than or equal to the second time interval.

[0011] By controlling the discharge of the power battery within a certain period of time, the impact on charging efficiency can be minimized while suppressing lithium plating, and abnormal discharge caused by long-term discharge can be avoided.

[0012] In a possible implementation, the method further includes: while controlling the power battery to stop discharging, sending second charging request information to the charging pile based on the charging matching table, wherein the second charging request information is used to request the charging pile to charge the power battery.

[0013] In a second aspect, a battery management system is provided, including: an acquisition module for acquiring the negative electrode potential of the power battery during the charging process of the power battery; and a control module for controlling the power battery to discharge when the difference between the negative electrode potential and a preset potential is less than or equal to a safety threshold.

[0014] In one possible implementation, the control module is specifically used to: when the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, send a first charging request message to the charging pile, and the first charging request message is used to request a charging current of 0; when the actual charging current of the power battery collected is less than or equal to the current threshold, control the power battery to discharge.

[0015] In a possible implementation, the control module is further configured to: control the power battery to stop discharging when a duration during which the first charging request information has been sent is greater than or equal to a first time interval.

[0016] In a possible implementation, the control module is further configured to: control the power battery to stop discharging when a duration of controlling the power battery to discharge is greater than or equal to a second time interval.

[0017] In one possible implementation, the battery management system further includes: a communication module for sending a second charging request message to the charging pile based on a charging matching table while controlling the power battery to stop discharging, wherein the second charging request message is used to request the charging pile to charge the power battery.

[0018] In a third aspect, a battery management system is provided, comprising a memory and a processor, wherein the memory is used to store instructions, and the processor is used to read the instructions and execute the method in the above-mentioned first aspect and any possible implementation of the first aspect based on the instructions.

[0019] In a fourth aspect, a readable storage medium is provided for storing a computer program for executing the method in the above-mentioned first aspect and any possible implementation manner of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0021] Figure 1 A schematic block diagram of a battery system applicable to an embodiment of the present application is shown.

[0022] Figure 2 It is a schematic block diagram of the power battery charging method disclosed in an embodiment of the present application.

[0023] Figure 3 It is a schematic diagram of the polarized first-order RC equivalent circuit model disclosed in the embodiment of the present application.

[0024] Figure 4 It is a schematic flow chart of the method for charging a power battery disclosed in an embodiment of the present application.

[0025] Figure 5 It is a schematic block diagram of the battery management system disclosed in the embodiment of the present application.

[0026] Figure 6 This is another schematic block diagram of the battery management system disclosed in the embodiment of the present application. DETAILED DESCRIPTION

[0027] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0028] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly perpendicular, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0029] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0030] In the field of new energy, power batteries are the primary power source for electrical devices such as vehicles, ships, and spacecraft, and their importance is self-evident. Currently, most power batteries on the market are rechargeable batteries, with lithium-ion batteries and lithium-ion polymer batteries being the most common.

[0031] Normally, during the charging process of lithium-ion batteries, lithium ions are deintercalated from the positive electrode and embedded in the negative electrode. However, when some abnormal conditions occur (for example, charging the battery at low temperature, or charging the battery at a large charge rate or charging voltage), and the lithium ions deintercalated from the positive electrode cannot be embedded in the negative electrode, then the lithium ions can only be deposited on the surface of the negative electrode, forming a layer of gray substance. This phenomenon is called lithium plating.

[0032] Lithium plating not only reduces battery performance and significantly shortens cycle life, but also limits the battery's fast charging capacity and may cause catastrophic consequences such as combustion and explosion.

[0033] In view of this, an embodiment of the present application provides a method for charging a power battery, which is beneficial for solving the lithium plating problem of the power battery, thereby improving the performance of the power battery.

[0034] Figure 1A battery system 100 applicable to an embodiment of the present application is shown. The battery system 100 may include: a power battery 110 and a battery management system (BMS) 120.

[0035] Specifically, the power battery 110 may include at least one battery module, which can provide energy and power for the electric vehicle. In terms of battery type, the power battery 110 can be a lithium-ion battery, a lithium metal battery, a lead-acid battery, a nickel-chromium battery, a nickel-metal hydride battery, a lithium-sulfur battery, a lithium-air battery, or a sodium-ion battery, etc., which is not specifically limited in the embodiments of this application. In terms of battery size, in the embodiments of this application, the battery module in the power battery 110 can be a battery cell, a battery pack, or a battery pack, which is not specifically limited in the embodiments of this application.

[0036] In addition, in order to intelligently manage and maintain the power battery 110, prevent battery failure, and extend the battery life, the battery system 100 is generally also provided with a BMS 120. The BMS 120 is connected to the power battery 110 and is used to monitor and collect parameters of the power battery 110. The BMS 120 can also control and manage the power battery 110 based on the parameters.

[0037] For example, the BMS 120 can be used to monitor parameters such as the voltage, current, and temperature of the power battery 110. Specifically, the BMS 120 can collect, in real time, the total voltage and current of the power battery 110, the voltage and current of individual cells in the power battery 110, and the temperature of at least one temperature measurement point in the power battery 110. Real-time, rapid, and accurate measurement of these parameters is essential for the proper operation of the BMS 120.

[0038] Optionally, the BMS 120 may further estimate various parameters of the power battery 110 , such as the state of charge (SOC), state of health (SOH), and state of power (SOP), based on the collected parameters of the power battery 110 .

[0039] Furthermore, after the BMS 120 obtains various parameters of the power battery 110 , various controls and managements of the power battery 110 may be implemented according to the various parameters.

[0040] For example, the BMS 120 can control the charge and discharge of the power battery 110 according to parameters such as SOC, voltage, and current, thereby ensuring normal energy supply and release of the power battery 110 .

[0041] For another example, the BMS 120 may also control components such as a cooling fan or a heating module according to parameters such as temperature to achieve thermal management of the power battery 110 .

[0042] For another example, the BMS 120 may also determine whether the power battery 110 is in a normal operating state based on parameters such as voltage and SOH, so as to implement fault diagnosis and early warning of the power battery 110 .

[0043] Alternatively, as Figure 1 As shown, the battery system 100 can establish connections with a charging device 101 and an electric device 102 to realize charging and discharging of the power battery 100 .

[0044] Optionally, the charging device 101 may include but is not limited to a charging pile, and may also be referred to as a charger.

[0045] Optionally, the electric device 102 may include but is not limited to a power vehicle or an external device.

[0046] Figure 2 FIG2 shows a schematic block diagram of a method 200 for charging a power battery disclosed in an embodiment of the present application. Optionally, the power battery in the embodiment of the present application may be Figure 1 The power battery 110 shown, the method 200 can be applied to Figure 1 In other words, the method 200 may be performed by the BMS 120 in the battery system 100 shown in FIG. Figure 1 The BMS 120 in the battery system 100 shown in FIG. Figure 2 As shown, the method 200 includes some or all of the following:

[0047] S210 , during the charging process of the power battery, obtaining the potential of the negative electrode of the power battery.

[0048] S220 , when the difference between the negative electrode potential and the preset potential is less than or equal to a safety threshold, controlling the power battery to discharge.

[0049] It should be understood that an electrode generally refers to the location in a battery where redox reactions with the electrolyte solution occur. Electrodes are classified as positive or negative. Generally, the positive electrode is the cathode, where it gains electrons and undergoes a reduction reaction; the negative electrode is the anode, where it loses electrons and undergoes an oxidation reaction. In other words, the potential of the negative electrode can be called the anode potential, while the potential of the positive electrode can be called the cathode potential.

[0050] Normally, during the charging process of a power battery, the negative electrode potential of the power battery will gradually decrease. When the negative electrode potential of the power battery drops to a preset potential, lithium metal will be precipitated. This preset potential can also be called the lithium precipitation potential, that is, the critical potential for lithium precipitation. Taking a lithium-ion battery with a graphite negative electrode system as an example, during the charging process of a lithium-ion battery, the electrode polarization occurs, that is, the negative electrode potential drops, while the positive electrode potential rises. When the negative electrode potential drops to 0V (vs Li / Li + ), lithium metal will be deposited on the surface of the negative electrode, which will damage the battery performance. In severe cases, it may also cause safety accidents such as thermal runaway.

[0051] The applicant has discovered that controlling the discharge of a power battery during charging can promote lithium metal reintercalation and inhibit the continued accumulation of precipitated lithium metal. However, since the BMS requires a certain amount of time to react when controlling the discharge of the power battery, for example, the BMS may need to negotiate with the charging station to stop charging the power battery before the power battery can begin discharging. Therefore, if the BMS controls the power battery to discharge only when the negative electrode potential of the power battery reaches a preset potential, lithium metal may still be precipitated on the negative electrode surface, thereby impairing battery performance.

[0052] In the embodiment of the present application, a safety threshold is set so that when the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, the BMS controls the power battery to discharge. That is to say, the BMS controls the power battery to discharge before the negative electrode potential reaches the preset potential, which can avoid the precipitation of lithium metal on the negative electrode surface before the power battery is discharged, thereby improving the safety performance of the battery.

[0053] Optionally, in the embodiment of the present application, the safety threshold cannot be too large. That is, the BMS cannot control the power battery to discharge when the potential of the negative electrode of the power battery is far from dropping to the preset potential. In this case, although the precipitation of lithium metal on the negative electrode surface can be avoided, the charging efficiency will also be affected. Optionally, the safety threshold can be set based on battery performance, charging speed requirements, and safety requirements. For example, the safety threshold can be 5mV, 10mV, or 15mV.

[0054] Optionally, in the embodiment of the present application, the setting of the safety threshold may also take into account the accuracy of obtaining the negative electrode potential, that is, the error of the negative electrode potential.

[0055] In S210 , there is no specific limitation on how to obtain the negative electrode potential of the power battery. For example, the negative electrode potential of the battery can be estimated using a negative electrode potential estimation model, or can be obtained by actual measurement using a three-electrode battery with a reference electrode.

[0056] In one embodiment, for a two-electrode battery, the BMS can separate the positive and negative electrodes of the battery using a negative electrode potential estimation model to accurately simulate the changes in the negative and positive electrode potentials during charging. For example, equivalent circuit models, electrochemical models, or equivalent circuit and electrochemical coupled models can be used.

[0057] In another embodiment, the BMS can also obtain the negative electrode potential of the battery by collecting the negative electrode potential of a three-electrode battery with a reference electrode and the potential of the reference electrode, wherein the three-electrode battery refers to a battery that includes a positive electrode and a negative electrode in addition to the positive electrode and the negative electrode of a traditional two-electrode battery, and a new reference electrode is added. The reference electrode is, for example, a lithium metal reference electrode, a lithium alloy reference electrode, or a copper wire in-situ lithium-plated reference electrode.

[0058] Specifically, the BMS can establish a polarity equivalent model for a three-electrode battery. The polarity equivalent model can include positive and negative electrode parameters to reflect the external and internal characteristics of the three-electrode battery, so as to accurately predict the negative electrode potential. The polarity equivalent model can include a Rint model, a polarity first-order RC equivalent circuit model, a polarity second-order RC equivalent circuit model, etc.

[0059] Figure 3 Schematic diagram of the first-order RC equivalent circuit model of the embodiment of the present application is shown. Figure 3 As shown in the figure, Ut is the terminal voltage of the whole battery; Uca and Uan are the potentials of the positive electrode relative to the reference electrode and the negative electrode relative to the reference electrode, respectively. OCVca and OCVan represent the open-circuit voltage of the positive electrode and the open-circuit voltage of the negative electrode, respectively. Rca_0 and Ran_0 represent the ohmic internal resistance of the positive electrode and the ohmic internal resistance of the negative electrode, respectively. Uca_p and Uan_p represent the polarization voltage of the positive electrode and the polarization voltage of the negative electrode, respectively. Rca_p and Ran_p represent the polarization internal resistance of the positive electrode and the polarization internal resistance of the negative electrode, respectively. Cca_p and Can_p represent the polarization capacitance of the positive electrode and the polarization capacitance of the negative electrode, respectively. I represents the current. Uca_p' and Uan_p' represent the derivatives of Uca_p and Uan_p, respectively.

[0060] First, the open circuit voltage OCVca of the positive electrode and the open circuit voltage OCVan of the negative electrode can be obtained by actual measurement. Then, according to formulas (1) to (5), an optimization algorithm such as the least squares method or genetic algorithm is combined to calibrate the model parameters Rca_0, Ran_0, Rca_p, Ran_p, Cca_p and Can_p. Finally, the extended Kalman filter algorithm, the proportional-integral-differential (PID) algorithm or the Romberg observer are used to estimate the negative electrode potential.

[0061] Ut=Uca–Uan (1)

[0062] Uca=OCVca+I*Rca_0+Uca_p (2)

[0063] Uan=OCVan+I*Ran_0+Uan_p (3)

[0064] Uca_p'=I / Cca_p-Uca_p / (Rca_p*Cca_p) (4)

[0065] Uan_p'=I / Can_p-Uan_p / (Ran_p*Can_p) (5)

[0066] The following briefly introduces an embodiment of estimating the negative electrode potential using the extended Kalman filter algorithm. The extended Kalman filter algorithm mainly consists of the state equation (6) and the observation equation (7), and then combines the recursive equations (8)-(12) to iteratively update the time and state to achieve state estimation.

[0067] X k+1 =A k X k +B k U k +Q k (6)

[0068] Y k =C k X k +R k (7)

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] Where X is the state variable to be estimated, U is the controllable input, Y is the output, Q and R represent the system error and measurement error, respectively, P is the covariance matrix of the estimated error, the subscript k represents the variable at time k, and the superscript T indicates the matrix transpose operation. A, B, C, and D are coefficient matrices.

[0075] Substitute the values of X, A, B, C, Q, and R into the above equation:

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] R k =0.01

[0082] The negative electrode potential can be obtained through the negative electrode potential estimation equation:

[0083]

[0084] Among them, SOC can be obtained through the ampere-hour integration method.

[0085] Optionally, in an embodiment of the present application, the BMS controls the power battery to discharge, and parameters such as the current size and duration of the power battery discharge can be fixed or adjusted in real time.

[0086] In one example, the BMS may control the power battery to discharge based on the same discharge parameters. For example, the discharge parameters may be fixedly configured as a current of 10 A and a discharge time of 20 s.

[0087] In another example, the BMS may control the discharge of the power battery based on discharge parameters determined in real time. For example, the discharge parameters of the power battery may be determined based on state parameters of the power battery. The state parameters of the power battery may include, for example, temperature, SOC, and SOH.

[0088] Optionally, the discharge parameters of the power battery can be determined based on the SOC interval in which the power battery's SOC falls. Generally speaking, the higher the SOC of the power battery, the higher the risk of lithium deposition in the battery. The BMS can pre-configure the discharge duration and / or discharge current corresponding to different SOC intervals. For example, the discharge duration corresponding to a high SOC interval can be greater than the discharge duration corresponding to a low SOC interval. For another example, the discharge current corresponding to a high SOC interval can be greater than the discharge current corresponding to a low SOC interval.

[0089] Dynamically adjusting the discharge parameters of the power battery based on the state parameters of the power battery can better balance the relationship between lithium plating and charging speed, thereby better achieving fast and safe charging.

[0090] It should be noted that determining the power battery's discharge parameters and controlling the power battery's discharge can be considered two independent steps that do not interfere with each other. In other words, there is no necessary timing relationship between determining the power battery's discharge parameters and controlling the power battery's discharge. If the power battery's discharge parameters are determined first, the power battery's discharge is controlled based on the determined discharge parameters. If the power battery's discharge parameters are determined later, the power battery's discharge is controlled based on the previously determined discharge parameters.

[0091] Optionally, in an embodiment of the present application, the method 200 further includes: when the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, sending a first charging request message to the charging pile, the first charging request message being used to request a charging current of 0; when the actual charging current of the power battery collected is less than or equal to the current threshold, controlling the power battery to discharge.

[0092] Typically, after the BMS is physically connected to the charging pile and powered on, the low-voltage auxiliary power supply is turned on, and the handshake startup phase begins, sending a handshake message before performing insulation monitoring. After the insulation monitoring is completed, the handshake identification phase begins, during which both parties can send identification messages to determine the necessary information about the power battery and charging pile. After the charging handshake phase is completed, the charging pile and BMS enter the charging parameter configuration phase. During this phase, the charging pile can send a message to the BMS indicating its maximum output capacity, allowing the BMS to determine whether charging is possible based on the maximum output capacity of the charging pile. After the charging parameter configuration phase is completed, the charging pile and BMS can enter the charging phase.

[0093] During the charging process of the power battery, the BMS will send the battery charging requirements to the charging pile, and then the charging pile can adjust the charging voltage and charging current according to the battery charging requirements to ensure the normal charging process. As an example, the battery charging requirements will carry the charging request current. The charging pile will then output current to the power battery based on the charging request current sent by the BMS. The BMS can collect the charging current of the power battery, that is, the actual charging current in the embodiment of the present application.

[0094] In the embodiment of the present application, the first charging request information is similar to the battery charging request, except that the charging request current carried in the battery charging request is 0. That is, the first charging request information is used to request the charging current to be 0 from the charging pile. After receiving the first charging request information, the charging pile controls the charging current output to the power battery to be 0. Since the actual charging current of the power battery gradually decreases after the BMS sends the first charging request information to the charging pile, if the BMS immediately controls the power battery to discharge after sending the first charging request information to the charging pile, the effect of discharging on suppressing lithium deposition in the battery may be reduced.

[0095] In one example, the actual charging current of the power battery is collected in real time, and the power battery is controlled to discharge only when the actual charging current is less than or equal to a current threshold, for example, the current threshold is 50A.

[0096] In another example, the power battery can also be controlled to discharge after a preset time after the first charging request information is sent to the charging pile. The preset time can be an empirical value based on the time from the time the BMS sends the first charging request information to the charging pile to the time when the actual charging current of the power battery drops to the current threshold.

[0097] Optionally, in an embodiment of the present application, the method 200 further includes: controlling the power battery to stop discharging when the duration for which the first charging request information has been sent is greater than or equal to a first preset time interval.

[0098] For example, a timer may be started when the BMS sends the first charging request information to the charging pile. The timer duration may be the first preset time interval. When the timer times out, the power battery is controlled to stop discharging. For example, the timer duration may be 60 seconds, that is, the first preset time interval is 60 seconds.

[0099] For another example, the timing may start when the BMS sends the first charging request information to the charging pile, and when the timing reaches a first preset time interval, the power battery is controlled to stop discharging. For example, the first preset time interval is 60 seconds.

[0100] Optionally, in another embodiment of the present application, the method 200 further includes: controlling the power battery to stop discharging when the duration of controlling the power battery to discharge is greater than or equal to a second preset time interval.

[0101] For example, a timer may be started when the BMS starts discharging the power battery. The timer may be set to a second preset time interval. When the timer times out, the power battery is controlled to stop discharging. For example, the timer may be set to 20 seconds, meaning the second preset time interval is 20 seconds.

[0102] For another example, the timing may be started when the BMS controls the power battery to start discharging, and when the timing reaches a second preset time interval, the power battery is controlled to stop discharging. For example, the second preset time interval is 20 seconds.

[0103] It should be understood that the first preset time interval and the second preset time interval are configurable.

[0104] By controlling the discharge of the power battery within a certain period of time, the impact on charging efficiency can be minimized while suppressing lithium plating, and abnormal discharge caused by long-term discharge can be avoided.

[0105] Optionally, in an embodiment of the present application, the method 200 further includes: when controlling the power battery to stop discharging, sending second charging request information to the charging pile based on the charging matching table, wherein the second charging request information is used to request the charging pile to charge the power battery.

[0106] Specifically, when the BMS controls the power battery to stop discharging, it can send a second charging request message to the charging pile based on the charging matching table. The second charging request message is similar to the battery charging requirement described above. The charging request current carried in the second charging request message is not 0, that is, the charging pile is requested to output current to the power battery. In other words, the BMS will store a charging matching table internally. The charging matching table may include the correspondence between the charging request current and various state parameters of the power battery. When the BMS controls the power battery to stop discharging, it can obtain the corresponding charging request current from the charging matching table based on the current state parameters of the power battery and send it to the charging pile through the second charging request message. For example, the BMS can obtain the charging request current corresponding to the current SOC from the charging matching table. After receiving the second charging request message, the charging pile outputs a non-zero charging current to the power battery, that is, charges the power battery. The BMS can then repeat steps 210 and 220.

[0107] Optionally, in the embodiment of the present application, the method 200 further includes: when the power battery is in a fully charged state or a unloaded state, controlling the power battery to discharge.

[0108] If the power battery is in a fully charged state or a drawn-gun state, it is not clear whether the current state of the power battery has a risk of lithium deposition. By controlling the discharge of the power battery, lithium deposition can be suppressed when the power battery has a risk of lithium deposition, thereby improving the safety performance of the power battery.

[0109] It should be noted that the discharge object of the power battery can be, for example, Figure 1 The electrical device 102 shown may also be a charging pile, which is not limited in the embodiment of the present application.

[0110] Figure 4 FIG. 4 is a schematic flow chart of a method 400 for charging a power battery according to an embodiment of the present application. Figure 4 As shown, the method 400 may be executed by a BMS, and the method 400 may include the following parts to obtain the entire content:

[0111] S401, determining whether the power battery is in a charging state;

[0112] S402 , if it is determined in S401 that the power battery is in a charging state, the BMS collects the negative electrode potential of the power battery in real time, for example, by using the above-mentioned three-electrode battery to obtain the negative electrode potential of the power battery through actual measurement.

[0113] Optionally, if it is determined in S401 that the power battery is not in a charging state, step S409 is executed;

[0114] S403, determining whether (negative electrode potential - preset potential) is less than or equal to a safety threshold, where the safety threshold is, for example, 10 mV;

[0115] S404, if the result of the determination in S403 is yes, then sending a battery charging request with a charging request current of 0 to the charging pile, and collecting the actual charging current of the power battery in real time and starting timing;

[0116] Optionally, if the judgment result in S403 is no, return to step S402;

[0117] S405, determining whether the actual charging current of the power battery is less than 50A;

[0118] S406, if the judgment result in S405 is yes, then control the power battery to discharge at a current of 10A;

[0119] Optionally, if the judgment result in S405 is no, return to step S404;

[0120] S407, determining whether the discharge time of the power battery is greater than or equal to 20 seconds, or whether the time measured in step S404 is greater than or equal to 60 seconds;

[0121] S408, if the result of the judgment in S407 is yes, the power battery is controlled to stop discharging, and the charging pile is requested to charge the power battery according to the charging matching table, that is, the execution returns to step S401;

[0122] Optionally, if the judgment result in S407 is no, return to step S406;

[0123] S409, if it is determined in S401 that the power battery is in a non-charging state, then determine whether the power battery is in a fully charged state or a gun-drawn state;

[0124] S410: If it is determined in S409 that the power battery is in a fully charged state or the gun is unloaded, the power battery is controlled to discharge at a current of 10 A for 20 seconds;

[0125] Optionally, if it is determined in S409 that the power battery is not in a fully charged state or in a gun-drawn state, the method 400 ends.

[0126] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0127] The above describes in detail the method for charging the power battery of the embodiment of the present application. Figure 5 and Figure 6 The battery management system of the embodiment of the present application is described in detail. The technical features described in the method embodiment are applicable to the following device embodiment.

[0128] Figure 5 FIG. 5 shows a schematic block diagram of a battery management system 500 according to an embodiment of the present application. Figure 5 As shown, the battery management system 500 includes:

[0129] An acquisition module 510 is configured to acquire the negative electrode potential of the power battery during the charging process of the power battery;

[0130] The control module 520 is configured to control the power battery to discharge when the difference between the negative electrode potential and the preset potential is less than or equal to a safety threshold.

[0131] In the embodiment of the present application, a safety threshold is set so that when the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, the BMS controls the power battery to discharge. That is to say, the BMS controls the power battery to discharge before the negative electrode potential reaches the preset potential, which can avoid the precipitation of lithium metal on the negative electrode surface before the power battery is discharged, thereby improving the safety performance of the battery.

[0132] Optionally, in an embodiment of the present application, the control module 520 is specifically used to: send a first charging request message to the charging pile when the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, and the first charging request message is used to request a charging current of 0; and control the power battery to discharge when the actual charging current of the power battery collected is less than or equal to the current threshold.

[0133] Optionally, in an embodiment of the present application, the control module 520 is further configured to: control the power battery to stop discharging when a duration for which the first charging request information has been sent is greater than or equal to a first time interval.

[0134] Optionally, in the embodiment of the present application, the control module 520 is further configured to: control the power battery to stop discharging when the duration of controlling the power battery to discharge is greater than or equal to a second time interval.

[0135] Optionally, in an embodiment of the present application, the battery management system 500 further includes: a communication module for sending a second charging request message to the charging pile based on a charging matching table while controlling the power battery to stop discharging, wherein the second charging request message is used to request the charging pile to charge the power battery.

[0136] It should be understood that the battery management system 500 according to the embodiment of the present application may correspond to the BMS in the method embodiment of the present application, and the above and other operations and / or functions of each unit in the battery management system 500 are respectively to achieve Figure 2 and Figure 4 For the sake of brevity, the corresponding processes of the battery management system in the illustrated method are not described here in detail.

[0137] Figure 6 FIG. 1 shows a schematic block diagram of a battery management system 600 according to another embodiment of the present application. Figure 6 As shown, the battery management system 600 includes a processor 610 and a memory 620, wherein the memory 620 is used to store instructions, and the processor 610 is used to read the instructions and execute the methods of the various embodiments of the present application based on the instructions.

[0138] The memory 620 may be a separate device independent of the processor 610 , or may be integrated into the processor 610 .

[0139] Alternatively, as Figure 6 As shown, the battery management system 600 may further include a transceiver 630, and the processor 610 may control the transceiver 630 to communicate with other devices such as charging piles. Specifically, it may send information or data to other devices, or receive information or data sent by other devices.

[0140] An embodiment of the present application further provides a readable storage medium for storing a computer program, wherein the computer program is used to execute the methods of the various embodiments of the present application described above.

[0141] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0142] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0143] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0144] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0145] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0146] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), etc.

[0147] Various media that can store program codes, such as RAM), magnetic disks or optical disks.

[0148] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for charging a power battery, characterized in that: include: During the charging process of the power battery, obtaining the negative electrode potential of the power battery; When the difference between the negative electrode potential and the preset potential is less than or equal to a safety threshold, controlling the power battery to discharge includes: When the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, sending first charging request information to the charging pile, where the first charging request information is used to request that the charging current be 0; When it is collected that the actual charging current of the power battery is less than or equal to a current threshold, the power battery is controlled to discharge.

2. The method according to claim 1, characterized in that The method further comprises: When the duration for which the first charging request information has been sent is greater than or equal to a first time interval, the power battery is controlled to stop discharging.

3. The method according to claim 1, characterized in that The method further comprises: When the duration of controlling the power battery to discharge is greater than or equal to the second time interval, controlling the power battery to stop discharging.

4. The method according to claim 2 or 3, characterized in that The method further comprises: In the case of controlling the power battery to stop discharging, second charging request information is sent to the charging pile based on the charging matching table, where the second charging request information is used to request the charging pile to charge the power battery.

5. A battery management system, characterized in that: include: An acquisition module, configured to acquire the negative electrode potential of the power battery during the charging process of the power battery; A control module is configured to control the power battery to discharge when the difference between the negative electrode potential and the preset potential is less than or equal to a safety threshold; the control module is specifically configured to: When the difference between the negative electrode potential and the preset potential is less than or equal to the safety threshold, sending first charging request information to the charging pile, where the first charging request information is used to request that the charging current be 0; When it is collected that the actual charging current of the power battery is less than or equal to a current threshold, the power battery is controlled to discharge.

6. The battery management system according to claim 5, characterized in that: The control module is further configured to: When the duration for which the first charging request information has been sent is greater than or equal to a first time interval, the power battery is controlled to stop discharging.

7. The battery management system according to claim 5, characterized in that: The control module is further configured to: When the duration of controlling the power battery to discharge is greater than or equal to the second time interval, controlling the power battery to stop discharging.

8. The battery management system according to claim 6 or 7, characterized in that: The battery management system further includes: The communication module is used to send second charging request information to the charging pile based on the charging matching table when controlling the power battery to stop discharging, wherein the second charging request information is used to request the charging pile to charge the power battery.

9. A battery management system for a power battery, characterized in that: The method comprises a memory and a processor, wherein the memory is used to store instructions, and the processor is used to read the instructions and execute the method according to any one of claims 1 to 4 based on the instructions.

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