Method for controlling discharge of battery, battery management system and electric device
By acquiring the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage, and calculating the static and dynamic discharge power, the problem of insufficient battery discharge control accuracy is solved, and dynamic adjustment and safe control of battery power are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LIGOO (SHAN DONG) NEW ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2026-06-08
- Publication Date
- 2026-07-10
Smart Images
Figure CN122354293A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of battery technology, and in particular relates to a method for controlling battery discharge, a battery management system, and an electrical device. Background Technology
[0002] Batteries are the core component of new energy vehicles, and their power output capability determines the vehicle's driving performance and the operational stability of the energy storage system. Typically, a battery's power output capability is characterized by its maximum discharge power.
[0003] In related technologies, the upper limit of battery discharge power is typically determined by looking up a table based on the battery's temperature and SOC (State of Charge). This method is a static lookup method, and it cannot accurately determine the upper limit of battery discharge power when the battery's operating parameters change.
[0004] Therefore, accurately determining the power output capability of a battery in order to precisely control battery discharge is a problem that urgently needs to be solved in this field. Summary of the Invention
[0005] This application provides a method for controlling battery discharge, a battery management system, and an electrical device, which can dynamically adjust the power output capability of the battery and improve the control accuracy of battery discharge power.
[0006] In a first aspect, embodiments of this application provide a method for controlling battery discharge. The method includes: acquiring the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage; determining the battery's static discharge power based on the open-circuit voltage, DC resistance, and discharge cutoff voltage, wherein the static discharge power characterizes the maximum power output by the battery in a non-polarized state; determining the battery's power adjustment amount based on the battery's minimum output voltage, DC resistance, and discharge cutoff voltage, wherein the power adjustment amount characterizes the additional power released by the battery when discharged to the discharge cutoff voltage in a polarized state; adjusting the battery's actual discharge power based on the power adjustment amount to obtain dynamic discharge power; and controlling battery discharge based on the static discharge power and dynamic discharge power.
[0007] Secondly, embodiments of this application also provide a battery management system, which includes: a data acquisition device for acquiring the open-circuit voltage, DC resistance, and discharge cutoff voltage of the battery; a processor for determining the static discharge power of the battery based on the open-circuit voltage, DC resistance, and discharge cutoff voltage, wherein the static discharge power characterizes the maximum power output by the battery in a non-polarized state; determining the power adjustment amount of the battery based on the minimum output voltage, DC resistance, and discharge cutoff voltage, wherein the power adjustment amount characterizes the additional power released by the battery when discharging to the discharge cutoff voltage in a polarized state; adjusting the actual discharge power of the battery based on the power adjustment amount to obtain the dynamic discharge power; and controlling the battery discharge based on the static discharge power and the dynamic discharge power.
[0008] Thirdly, embodiments of this application also provide an electrical device, which includes a battery and a battery management system as described in the second aspect.
[0009] Fourthly, embodiments of this application also provide an electronic device, which includes: a processor and a memory storing computer program instructions; the processor executes the computer program instructions to implement the method for controlling battery discharge as described in the first aspect.
[0010] Fifthly, embodiments of this application provide a computer-readable storage medium storing computer program instructions that, when executed by a processor, implement the method for controlling battery discharge as described in the first aspect.
[0011] In a sixth aspect, embodiments of this application provide a computer program product in which instructions, when executed by a processor of an electronic device, cause the electronic device to perform the method for controlling battery discharge as described in the first aspect.
[0012] As described above, in this embodiment, the open-circuit voltage, DC resistance, and discharge cutoff voltage of the battery are obtained, and the static discharge power is calculated accordingly to characterize the theoretical maximum output capability of the battery in a non-polarized state. Simultaneously, a power adjustment amount is determined based on the battery's minimum output voltage, DC resistance, and discharge cutoff voltage to quantify the additional power released by the battery in the current polarized state. The actual discharge power is then dynamically adjusted based on this power adjustment amount to obtain the dynamic discharge power. Since the minimum output voltage of a single battery cell dynamically drops when the battery is in a polarized state, this application quantifies the additional power released by the battery in a polarized state based on the minimum output voltage of the single battery cell. This allows the dynamic discharge power to adaptively adjust in real time following changes in the minimum output voltage. Combined with the static discharge power, this achieves dynamic adjustment of the battery's power output capability, overcoming the shortcomings of the existing static lookup table method, which cannot adapt to changes in operating parameters, and improving the control accuracy of the battery discharge power. Attached Figure Description
[0013] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 This is one of the flowcharts illustrating a method for controlling battery discharge provided in an embodiment of this application; Figure 2 This is a second schematic flowchart of a method for controlling battery discharge provided in one embodiment of this application; Figure 3 This is a schematic diagram of the structure of a battery management system provided in another embodiment of this application; Figure 4 This is a schematic diagram of the structure of an electrical device provided in another embodiment of this application; Figure 5 This is a schematic diagram of the structure of an electronic device provided in another embodiment of this application. Detailed Implementation
[0015] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.
[0016] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.
[0017] To facilitate understanding, before explaining the solution provided in this application, the background of the solution provided in this application will be explained first.
[0018] As the core of the new energy industry, power batteries and energy storage batteries directly determine the driving performance of new energy vehicles and the operational stability of energy storage systems. Power calculation is a crucial step in battery performance evaluation and system optimization. Battery internal resistance, as a key parameter affecting power output, energy loss, and lifespan, has made power calculation based on internal resistance a core research direction in the industry.
[0019] Typically, the internal resistance of a battery consists of ohmic internal resistance and polarization internal resistance. The internal resistance of power batteries is mostly in the milliohm range, while the internal resistance of energy storage batteries varies due to different system structures. Both types of batteries require precise measurement using specialized instruments. Ohmic internal resistance is an inherent resistance that is basically stable after manufacturing; polarization internal resistance changes dynamically with charging and discharging conditions. Both ohmic and polarization internal resistances are closely coupled with power; fluctuations in internal resistance affect the battery's discharge capacity. Specifically, during operation, the battery's internal resistance consumes energy and converts it into Joule heat. The battery's output power has a quantitative relationship with its internal resistance, i.e., Pmax = V. 2 / (4R), where Pmax is the maximum output power of the battery, V is the output voltage of the battery, and R is the internal resistance of the battery. In practical applications, the internal resistance of the battery changes dynamically with temperature, charge / discharge state, and aging degree. Low temperature or aging will increase the internal resistance, thereby reducing power output and energy utilization.
[0020] With the development of the new energy industry, the requirements for the power control accuracy of the two major batteries have also increased. Among them, the internal resistance of the power battery affects the vehicle's acceleration, range and fast charging safety, while the internal resistance of the energy storage battery is related to the system efficiency and stability. Power calculation based on internal resistance can provide precise support for the control of the battery's BMS (Battery Management System) and the optimization of charging and discharging strategies.
[0021] In existing technologies, HPPC (Hybrid Pulse Power Characterization) is typically used to test the battery's discharge power. The discharge power obtained through this method is the battery's maximum discharge power. By conducting multiple tests at different SOCs and temperatures, a SOC-temperature-discharge power table can be obtained, characterizing the relationship between SOC, ambient temperature, and discharge power. In practical applications, after determining the battery's current SOC and ambient temperature, the battery's discharge power can be determined by consulting the SOC-temperature-discharge power table. This retrieved discharge power is then used to determine the battery's maximum permissible discharge capacity for the entire vehicle.
[0022] It should be noted that the above scheme only discharges according to the expected power meter reading, heavily relying on the accuracy of SOC and ambient temperature detection, and ignoring the impact of dynamic changes in battery internal resistance on discharge power. Furthermore, SOC is usually an estimated value, and under long-term uncalibrated operating conditions, the correlation between SOC, ambient temperature, and discharge power can become inaccurate. Using the aforementioned correlation table to look up the battery's discharge power will be inaccurate, thus affecting the battery's control precision. Additionally, in the above scheme, the discharge power obtained through HPPC testing is the maximum discharge power, obtained after the battery has been fully rested. This method does not consider battery polarization, resulting in an overestimation of the measured discharge power and a tendency for undervoltage issues.
[0023] To address the problems existing in the prior art, this application provides a method for controlling battery discharge, a battery management system, and an electrical device. In this application embodiment, the minimum output voltage of the battery can reflect the polarization state of a single battery cell. Therefore, by quantifying the additional power released by a single battery cell in its polarized state based on the minimum output voltage, the battery's discharge power can be dynamically adjusted, thereby enabling a more accurate assessment of the battery's power output capability and improving the control precision of battery discharge.
[0024] The method for controlling battery discharge provided in the embodiments of this application will be described below. The battery management system can serve as the executing entity for the method provided in the embodiments of this application.
[0025] Figure 1 A schematic flowchart of a method for controlling battery discharge according to an embodiment of this application is shown. Figure 1 As shown, the method includes the following steps S101 to S105: Step S101: Obtain the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage.
[0026] In step S101, the battery is installed in an electrical device, for example, in a vehicle, to output electrical energy to the vehicle. In this embodiment, the battery can be a power battery or an energy storage battery.
[0027] In step S101, the open-circuit voltage of the battery is used to characterize the terminal voltage of the battery in a static, no-current-flow state, reflecting the current electromotive force of the battery. The DC resistance is the battery's DC internal resistance, which may include ohmic internal resistance and polarization internal resistance. The DC resistance typically changes dynamically with temperature, state of charge (SOC), and battery aging. The discharge cut-off voltage is the minimum safe voltage threshold at which the battery is allowed to discharge. It can be preset by the battery's chemical system and safety requirements. Generally, if the battery's discharge voltage exceeds this discharge cut-off voltage, continuing to discharge the battery will cause irreversible damage or pose a safety risk.
[0028] In this embodiment of the application, the above-mentioned parameters can be stored in the battery management system by means of real-time acquisition, table lookup, or pre-setting parameter values, or sent to the battery management system in real time, so that the battery management system can dynamically control the discharge power of the battery according to the above-mentioned parameters.
[0029] Step S102: Determine the static discharge power of the battery based on the open circuit voltage, DC resistance, and discharge cutoff voltage.
[0030] In step S102, the static discharge power is used to characterize the maximum power output of the battery in a non-polarized state; that is, in this embodiment, the static discharge power is the theoretical value under ideal conditions. In practical applications, this static discharge power can be used as an upper limit reference value for battery discharge power control.
[0031] In this embodiment, the static discharge power is determined based on the open-circuit voltage, DC resistance, and discharge cutoff voltage. Under the ideal assumption of non-polarization, the static discharge power still takes into account the engineering constraint that the actual depth of discharge of the battery is limited by the battery's discharge cutoff voltage. This makes the determined static discharge power more closely match the actual application scenario of the battery, thereby improving the control accuracy of battery discharge.
[0032] Step S103: Determine the corresponding power adjustment amount of the battery based on the battery's minimum output voltage, DC resistance, and discharge cutoff voltage.
[0033] In step S103, during the discharge process, the battery experiences polarization, causing its actual output voltage to be lower than its open-circuit voltage. The lowest voltage cell typically represents the bottleneck in the overall battery pack's discharge capacity. Therefore, in this embodiment, the minimum output voltage of the battery—the terminal voltage of the lowest voltage cell in the battery pack—is used as the feedback signal for real-time polarization sensing.
[0034] In step S103, the power adjustment amount is used to characterize the additional power released by the battery when it discharges to the discharge cutoff voltage in a polarized state.
[0035] It should be noted that when the battery undergoes high-current discharge, battery polarization causes the discharge voltage to drop. In this embodiment, the battery power adjustment is determined based on the battery's minimum output voltage, DC resistance, and discharge cutoff voltage. Specifically, when the battery is severely polarized, its minimum output voltage is close to the discharge cutoff voltage, and the power adjustment approaches zero; when the battery is less polarized, its minimum output voltage is close to the discharge cutoff voltage, and the power adjustment is positive.
[0036] Step S104: Adjust the actual discharge power of the battery based on the power adjustment amount to obtain the dynamic discharge power.
[0037] In step S104, the dynamic discharge power is used to characterize the upper limit of the system's maximum power that can be achieved when continuing to discharge from the current operating point to the discharge cutoff voltage, based on the current actual discharge power and combined with the additional power that the battery can release under the current polarization state. In this embodiment, the dynamic discharge power can be obtained by superimposing the power adjustment amount and the actual discharge power. The actual discharge power can be determined by the battery's discharge current and discharge voltage collected by the acquisition device.
[0038] In this embodiment, the dynamic discharge power can adaptively adjust in real time according to changes in the minimum output voltage, forming a negative feedback closed loop for the battery polarization state. Specifically, when the battery polarization is severe, the minimum output voltage is also low, and correspondingly, the power adjustment is also small. The dynamic discharge power is close to the battery's current actual discharge power, thereby automatically limiting further power increases and preventing undervoltage faults.
[0039] Step S105: Control the battery discharge based on the static discharge power and the dynamic discharge power.
[0040] In step S105, both static discharge power and dynamic discharge power can be used as the upper limit of the battery's discharge power. For example, the smaller of the static discharge power and the dynamic discharge power can be used as the upper limit of the battery's discharge power, or the upper limit of the battery's discharge power can be determined by weighting the static discharge power and the dynamic discharge power.
[0041] After determining the upper limit of the battery's discharge power, the battery management system can constrain the battery's discharge based on the upper limit to ensure that the battery discharges within a reasonable operating range, thereby improving the safety of battery operation.
[0042] Based on the scheme defined in steps S101 to S105 above, it can be understood that in this embodiment, by obtaining the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage, and calculating the static discharge power accordingly, the theoretical maximum output capability of the battery in a non-polarized state is characterized. Simultaneously, a power adjustment amount is determined based on the battery's minimum output voltage, DC resistance, and discharge cutoff voltage to quantify the additional power released by the battery in the current polarized state. The actual discharge power is then dynamically adjusted based on this power adjustment amount to obtain the dynamic discharge power. Since the minimum output voltage of a single battery cell dynamically drops when the battery is in a polarized state, this application quantifies the additional power released by the battery in a polarized state based on the minimum output voltage of the single battery cell. This allows the dynamic discharge power to adaptively adjust in real time following changes in the minimum output voltage. Combined with the static discharge power, this achieves dynamic adjustment of the battery's power output capability, overcoming the shortcomings of the existing static lookup table method, which cannot adapt to changes in operating parameters, and improving the control accuracy of the battery's discharge power.
[0043] The specific implementation process of the method provided in the embodiments of this application is described below.
[0044] In some embodiments, the static discharge power of a battery is determined by the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage. Therefore, before determining the static discharge power of a battery, it is necessary to first obtain the battery's open-circuit voltage and DC resistance.
[0045] In this embodiment of the application, the battery management system can obtain the battery temperature and the battery state of charge, and then determine the battery open-circuit voltage and DC resistance from the first relationship table and the second relationship table respectively based on the battery temperature and the state of charge.
[0046] In the above embodiments, the first relationship table includes the correlation between battery temperature, state of charge, and open-circuit voltage, and the second relationship table includes the correlation between battery temperature, state of charge, and DC resistance. The mapping relationship between the battery's characteristic parameters can be constructed by testing the offline battery, resulting in the first and second relationship tables. These tables are then stored in the battery management system. When battery discharge control is required, the battery management system can read the first and second relationship tables from a preset storage area.
[0047] For example, after obtaining the battery temperature and state of charge of the battery, the battery management system reads a first relation table from a preset storage area, finds the open circuit voltage corresponding to the current battery temperature and current state of charge from the first relation table, and finds the DC resistance corresponding to the current battery temperature and current state of charge from a second relation table.
[0048] The following example illustrates the construction of the two relational tables mentioned above.
[0049] First, the battery's discharge capacity needs to be determined. Specifically, first, adjust the temperature of the test chamber used to test the battery, for example, to 25°C, and wait for the battery to reach thermal equilibrium. Charge the battery at 1 / 3C to the full charge voltage V1_chrg_end, and then charge it at a constant voltage until the current reaches 0.1C, then stop charging. Next, adjust the test chamber temperature to 25°C. After the battery temperature reaches 25°C, let the battery rest for 2 hours. After resting for 2 hours, discharge the battery at a 1C current, first discharging to the discharge cutoff voltage V1_dischrg_end, and record the battery's discharge capacity Q1. Repeat this process multiple times to obtain multiple discharge capacities Q1. Calculate the average of these multiple discharge capacities Q1 to obtain the final discharge capacity Q2 of the battery. The measured discharge capacity Q2 is used in the construction of the first and second relational tables.
[0050] For constructing the first relational table, first adjust the temperature of the test chamber to 25℃. After the battery reaches thermal equilibrium, determine the charging rate of the battery based on its discharge capacity. For example, charge the battery at a charging rate of 1 / 3*Q2 until the battery reaches its full charge voltage V1_chrg_end. Then, perform constant voltage charging on the battery until the charging current reaches 0.1*Q2, and then stop charging. Next, continue adjusting the temperature of the test chamber to T1℃, wait for the battery to reach thermal equilibrium, and then let it stand for 1 hour. At this time, the battery voltage V1 is measured. Then, discharge the battery at a current of 1*Q2. After discharging for a period of time (e.g., 10 seconds), the battery voltage V2 is measured. At this time, the DC internal resistance of the battery DCR1 = (V1-V2) / Q2. The test chamber temperature was adjusted to 25℃. After the battery reached thermal equilibrium, it was allowed to stand for 1 hour. Then, the battery was discharged to SOC1 at a discharge rate of 1*Q2. After standing for 4 hours, the battery voltage was measured to obtain OCV1. The above process was repeated, with the temperature T1 successively adjusted to -20℃, -10℃, 0℃, 25℃, 45℃, and 55℃, and the SOC1 successively adjusted to 100%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, and 0%. The SOC1 and DCR1 corresponding to different temperatures T1 were obtained. The correspondence between temperature, state of charge, and open circuit voltage was constructed to obtain the first relationship table; the correspondence between temperature, state of charge, and DC resistance was constructed to obtain the second relationship table.
[0051] It should be noted that in practical applications, since the offline calibrated temperature and SOC are discrete, the first relationship table mentioned above essentially represents the discrete relationship between temperature, SOC, and open-circuit voltage, and the second relationship table essentially represents the discrete relationship between temperature, SOC, and DC resistance. However, in practical applications, temperature and SOC are continuously changing. Therefore, when determining the battery's open-circuit voltage by consulting the first relationship table, or determining the battery's DC resistance by consulting the second relationship table, if the current temperature is between two calibrated temperatures, linear interpolation can be used to determine the open-circuit voltage and DC resistance. Similarly, the same applies to SOC. When the battery's current SOC is between two calibrated SOCs, linear interpolation can be performed on the open-circuit voltage and DC resistance corresponding to the two calibrated SOCs to obtain the open-circuit voltage and DC resistance corresponding to the current SOC.
[0052] In the above embodiments, the complex parameter modeling and calculation process is transferred to the offline testing stage by means of offline calibration and online table lookup. The online stage only needs to perform simple table lookup and interpolation operations, which reduces the amount of calculation and improves the control efficiency of battery discharge.
[0053] In addition, the battery's discharge cutoff voltage is the minimum safe voltage threshold at which the battery is allowed to discharge. It is predetermined by the battery's chemical system and specifications and stored as a preset parameter in the battery management system's memory. In this embodiment, the discharge cutoff voltage can be a nominal value provided by the battery supplier. For example, for lithium iron phosphate batteries, the discharge cutoff voltage can be set to 2.8V; for ternary lithium batteries, the discharge cutoff voltage can be set to 3.0V.
[0054] In some embodiments, the determination of the battery's open-circuit voltage and DC resistance needs to be based on the battery's state of charge (SOC). To improve the accuracy of the SOC calculation, this embodiment uses a method of correcting the initial SOC obtained from a lookup table to determine the battery's SOC. Specifically, the battery management system first obtains the battery's output voltage, then determines the initial SOC from a third relation table based on the output voltage and battery temperature; performs ampere-hour integration based on the battery's output current to obtain a SOC correction value; and then corrects the initial SOC based on the SOC correction value to obtain the battery's SOC.
[0055] In the above embodiments, the third relationship table includes the correlation between output voltage, battery temperature and state of charge. Similar to the first and second relationship tables, the third relationship table is also obtained through offline testing. The initial state of charge of the battery under the current temperature and battery output voltage can be queried through the third relationship table.
[0056] For example, a temperature sensor can detect the battery temperature T2, a Hall sensor can detect the output current I1 flowing through the battery, and an AFE (Analog Front End) chip can acquire the battery output voltage V1_cell. The battery management system can communicate with the aforementioned temperature sensor, Hall sensor, and AFE chip to obtain the battery temperature, battery output current, and output voltage. Then, the battery management system can perform ampere-hour integration using the following formula (1) to correct the initial state of charge of the battery: (1) In formula (1), SOC is the state of charge of the battery. Let I be the initial state of charge of the battery, I be the output current of the battery, and Q be the capacity of the battery. In formula (1), I = I1 and Q = Q2. This is the correction value for the state of charge.
[0057] It should be noted that the ampere-hour integration method has a fast response speed and good real-time performance, continuously tracking the changes in SOC during the dynamic charging and discharging process of the battery. However, it suffers from cumulative error, with current measurement errors accumulating over time. While determining the battery's state of charge (SOC) by looking up a table can reduce cumulative error, it requires sufficient resting time for the battery, and the SOC obtained from the table also contains errors. In this embodiment, the high accuracy of the open-circuit voltage method and the high real-time performance of the ampere-hour integration method are combined to achieve complementary advantages. When the resting conditions are met, the open-circuit voltage method is used to calibrate the SOC, eliminating the cumulative error of the ampere-hour integration. During the dynamic charging and discharging process, the ampere-hour integration method is used to continuously track changes in SOC, ensuring real-time updates of the SOC.
[0058] In some embodiments, after determining the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage, the battery management system calculates the battery's static discharge power based on these three parameters.
[0059] Specifically, the battery management system obtains the voltage difference between the open-circuit voltage and the discharge cutoff voltage, as well as the battery's output voltage; then, based on the ratio between the voltage difference and the DC resistance, it determines the battery's maximum output current in the non-polarized state; next, based on the maximum output current and the output voltage, the static discharge power can be determined.
[0060] For example, the static discharge power of a battery can be expressed by formula (2): (2) In formula (2), This refers to the static discharge power of the battery. The open-circuit voltage of the battery is OCV; in this application, OCV = OCV1. This is the discharge cutoff voltage; V is the DC resistance of the battery; V is the output voltage of the battery.
[0061] In formula (2), This is the voltage difference between the open-circuit voltage and the discharge cutoff voltage. It represents the total allowable drop in the battery's terminal voltage from its initial open-circuit voltage to the discharge cutoff voltage under ideal, non-polarized conditions. The larger this voltage difference, the wider the usable voltage range from a fully charged state to the discharge cutoff state, theoretically allowing for a larger total output capacity and greater power output potential.
[0062] In formula (2), This represents the maximum current the battery can output under ideal, unpolarized conditions, starting from the current open-circuit voltage and continuing until the battery's terminal voltage drops to the discharge cutoff voltage. This current value reflects the battery's limiting current output capability under ideal conditions.
[0063] In the above embodiments, the calculation of the static discharge power of the battery is related to the battery's open-circuit voltage, discharge cut-off voltage, DC resistance, and output voltage, so that the calculated static discharge power can reflect the battery's current actual state and make the estimation of static discharge power closer to the battery's real-time operating conditions.
[0064] In some embodiments, after obtaining the minimum output voltage, DC resistance, and discharge cutoff voltage of the battery, the battery management system can determine the available voltage margin of the battery based on the difference between the minimum output voltage and the discharge cutoff voltage; then, based on the available voltage margin and the DC resistance, determine the polarization current of the battery in the polarized state; finally, based on the polarization current and the output voltage of the battery, determine the power adjustment amount.
[0065] For example, the power adjustment amount can be expressed by formula (3): (3) In formula (3), This is the power adjustment amount; This is the minimum output voltage.
[0066] It should be noted that in formula (3), This represents the battery's usable voltage margin, indicating the extent to which the voltage can drop further from its current actual terminal voltage (characterized by the minimum output voltage) until the discharge cutoff voltage is reached, under the current polarization state. This usable voltage margin reflects the battery's current degree of polarization and remaining discharge capacity. In cases of severe battery polarization, the polarization effect causes a significant drop in terminal voltage, resulting in a minimum output voltage... Approaching the discharge cutoff voltage At this point, the available voltage margin approaches zero or is a small positive value, indicating that the battery is nearing the end of its discharge cycle, and the remaining capacity and power that can be released are extremely limited; when the battery polarization is relatively light, the minimum output voltage... Keep away from the discharge cutoff voltage The battery has a large usable voltage margin, indicating that the battery has a large voltage drop potential and can release more power.
[0067] In formula (3), Polarization current represents the additional current that can be output based on the current DC internal resistance during the discharge process from the current operating point until the voltage drops to the discharge cutoff voltage, under the current polarization state. Specifically, when the battery polarization is severe, the minimum output voltage of the battery is... Approaching discharge cutoff voltage When the battery's usable voltage margin approaches zero and its polarization current approaches zero, it indicates that the battery no longer has the ability to output additional current; when the battery polarization is relatively light, the battery's minimum output voltage... Keep away from the discharge cutoff voltage The battery has a large usable voltage margin and a large positive polarization current, indicating that the battery has a large potential for additional current output. In addition, as can be seen from formula (3), the larger the DC internal resistance, the smaller the polarization current. The polarization current reflects the resistance of the battery internal resistance to the current output.
[0068] In the above embodiments, a hierarchical quantification mechanism based on available voltage margin, polarization current, and power adjustment is employed, enabling the battery management system to accurately perceive the remaining power potential under the current polarization state, providing a quantitative basis for subsequent adaptive power control. Furthermore, the upper limit of output power can be automatically adjusted according to changes in the minimum output voltage, forming a closed-loop feedback that improves the adaptability and robustness of battery control. In this embodiment, the calculation of the power adjustment depends only on the minimum output voltage, discharge cutoff voltage, and DC resistance. Therefore, even with a large estimation error in SOC, the power adjustment can still accurately reflect the battery's polarization state, thereby ensuring the accuracy of dynamic discharge power calculation and improving the battery management system's tolerance to SOC estimation errors.
[0069] In some embodiments, after determining the power adjustment amount, the battery management system can superimpose the actual discharge power using the power adjustment amount to obtain the dynamic discharge power.
[0070] For example, the battery management system can calculate the sum of the power adjustment and the actual discharge power as the dynamic discharge power. In practical applications, the dynamic discharge power can also be determined by weighting the power adjustment and the actual discharge power, where the weighting coefficient can be determined according to the battery's discharge scenario.
[0071] Through the above embodiments, the dynamic discharge power can track the change of the minimum output voltage in real time and automatically reduce the power limit when polarization is severe, effectively solving the problems of excessive power and undervoltage caused by neglecting the polarization effect in the traditional lookup table method.
[0072] In some embodiments, after determining the static discharge power and the dynamic discharge power, the battery management system determines the upper limit of the battery's discharge power based on the smaller of the static discharge power and the dynamic discharge power; and controls the battery discharge based on the upper limit of the discharge power. Specifically, if the actual discharge power of the battery is less than or equal to the upper limit of the discharge power, the battery is controlled to discharge according to the actual discharge power; if the actual discharge power of the battery is greater than the upper limit of the discharge power, the battery is controlled to discharge according to the upper limit of the discharge power.
[0073] In this embodiment, when the dynamic discharge power decreases due to severe polarization, a minimum power decision is made so that the upper limit of the battery's discharge power is the dynamic discharge power. At this time, the vehicle controller is limited to a lower power level, preventing the battery voltage from momentarily dropping below the discharge cutoff voltage due to excessive power requests, thus preventing over-discharge faults. In this embodiment, by limiting the duration of high-power discharge (indirectly achieved through the polarization accumulation effect), the aging rate of the battery under high-current conditions is reduced, extending the battery's lifespan. Moreover, when polarization is not severe, the upper limit of the discharge power is constrained by the static discharge power, allowing the vehicle to obtain higher power output, ensuring vehicle acceleration performance and driving experience; when polarization is severe, the upper limit of the discharge power is constrained by the dynamic discharge power, automatically reducing power output and prioritizing battery safety.
[0074] In some embodiments, Figure 2 A complete flowchart of the method provided in the embodiments of this application is shown, as follows: Figure 2 As shown, the method includes the following steps S201 to S208: In step S201, the battery management system obtains a first relationship table corresponding to temperature, state of charge, and open circuit voltage, and a second relationship table corresponding to temperature, state of charge, and DC resistance.
[0075] In step S202, the battery management system acquires the battery's output current, temperature, output voltage, and state of charge.
[0076] In step S203, the battery management system determines the open-circuit voltage and DC resistance of the battery under the current operating conditions from the first relation table and the second relation table based on the temperature and state of charge.
[0077] Step S204: Determine the static discharge power of the battery based on the open circuit voltage, DC resistance, and discharge cutoff voltage.
[0078] Step S205: Determine the corresponding power adjustment amount of the battery based on the battery's minimum output voltage, DC resistance, and discharge cutoff voltage.
[0079] Step S206: Adjust the actual discharge power of the battery based on the power adjustment amount to obtain the dynamic discharge power.
[0080] Step S207: The smaller of the static discharge power and the dynamic discharge power is determined as the upper limit of the battery's discharge power.
[0081] Step S208: Constrain the battery's discharge power according to the upper limit of discharge power.
[0082] This concludes the introduction of the methods provided in the embodiments of this application.
[0083] This application also provides a battery management system, such as... Figure 3 As shown, the battery management system includes a data acquisition device 31 and a processor 32.
[0084] The data acquisition device is used to collect the battery's open-circuit voltage, DC resistance, and discharge cut-off voltage. In this embodiment, the data acquisition device is a hardware module in the battery management system responsible for acquiring raw data, and may include, but is not limited to, voltage acquisition circuits (e.g., AFE analog front-end chip), current acquisition circuits (e.g., Hall sensor / shunt), and temperature acquisition circuits (e.g., temperature sensor). This data acquisition device is mainly used to convert the battery's physical quantities (e.g., voltage, current, temperature) into digital signals for the processor to perform calculations and control.
[0085] The processor determines the static discharge power of the battery based on the open-circuit voltage, DC resistance, and discharge cutoff voltage, whereby the static discharge power characterizes the maximum power output by the battery in a non-polarized state. It also determines the power adjustment amount based on the battery's minimum output voltage, DC resistance, and discharge cutoff voltage, whereby the power adjustment amount characterizes the additional power released by the battery when discharging to the discharge cutoff voltage in a polarized state. The processor adjusts the actual discharge power of the battery based on the power adjustment amount to obtain the dynamic discharge power. Finally, it controls the battery discharge based on the static discharge power and the dynamic discharge power.
[0086] The processor in the battery management system provided in this application embodiment can implement the various processes implemented in the aforementioned method embodiments. To avoid repetition, these processes will not be described again here.
[0087] This application also provides an electrical device, such as... Figure 4 As shown, the electrical device includes a battery 41 and the aforementioned battery management system 42.
[0088] In this application embodiment, the electrical device can be a device or system that uses a battery as a power source for all or part of its power and requires a battery management system to monitor and manage the battery. For example, the electrical device can be a new energy vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle), an energy storage system (e.g., residential energy storage, industrial and commercial energy storage, grid-side energy storage, etc.), or other usage equipment (e.g., power tools, drones, robots, etc.).
[0089] Figure 5 A schematic diagram of the hardware structure of an electronic device provided in an embodiment of this application is shown. This electronic device may be the battery management system described above.
[0090] The electronic device may include a processor 32 and a memory 502 storing computer program instructions.
[0091] Specifically, the processor 32 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.
[0092] Memory 502 may include mass storage for data or instructions. For example, and not limitingly, memory 502 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 502 may include removable or non-removable (or fixed) media. Where appropriate, memory 502 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 502 is non-volatile solid-state memory.
[0093] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.
[0094] The processor 32 reads and executes computer program instructions stored in the memory 502 to implement any of the methods for controlling battery discharge in the above embodiments.
[0095] In one example, the electronic device may also include a communication interface 503 and a bus 510. Wherein, as... Figure 5 As shown, the processor 32, memory 502, and communication interface 503 are connected through bus 510 and complete communication with each other.
[0096] The communication interface 503 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.
[0097] Bus 510 includes hardware, software, or both, that couples components of an electronic device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 510 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, this application contemplates any suitable bus or interconnect.
[0098] Furthermore, in conjunction with the battery discharge control methods described in the above embodiments, this application can provide a computer-readable storage medium for implementation. This computer-readable storage medium stores computer program instructions; when executed by a processor, these computer program instructions implement any of the battery discharge control methods described in the above embodiments.
[0099] Furthermore, in conjunction with the battery discharge control methods described in the above embodiments, this application can provide a computer program product for implementation. When the instructions in this computer program product are executed by the processor of an electronic device, the electronic device performs any of the battery discharge control methods described in the above embodiments.
[0100] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.
[0101] The functional modules shown in the above-described block diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.
[0102] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.
[0103] The foregoing flowcharts and / or block diagrams describing a method for controlling battery discharge, a battery management system, and an electrical device according to embodiments of the present disclosure have described various aspects of this disclosure. It should be understood that each block in the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to create a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowcharts and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by dedicated hardware performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.
[0104] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.
Claims
1. A method for controlling battery discharge, characterized in that, include: Obtain the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage; The static discharge power of the battery is determined based on the open-circuit voltage, the DC resistance, and the discharge cutoff voltage, wherein the static discharge power is used to characterize the maximum power output by the battery in a non-polarized state. The power adjustment amount corresponding to the battery is determined based on the minimum output voltage of the battery, the DC resistance, and the discharge cutoff voltage. The power adjustment amount is used to characterize the additional power released when the battery discharges to the discharge cutoff voltage under polarized conditions. The actual discharge power of the battery is adjusted based on the power adjustment amount to obtain the dynamic discharge power; The battery discharge is controlled based on the static discharge power and the dynamic discharge power.
2. The method according to claim 1, characterized in that, Determining the static discharge power of the battery based on the open-circuit voltage, the DC resistance, and the discharge cutoff voltage includes: Obtain the voltage difference between the open-circuit voltage and the discharge cutoff voltage, as well as the output voltage of the battery; The maximum output current of the battery in the non-polarized state is determined based on the ratio between the voltage difference and the DC resistance. The static discharge power is determined based on the maximum output current and the output voltage.
3. The method according to claim 1, characterized in that, The step of determining the power adjustment amount corresponding to the battery based on the battery's minimum output voltage, the DC resistance, and the discharge cutoff voltage includes: The available voltage margin of the battery is determined based on the difference between the minimum output voltage and the discharge cutoff voltage. The polarization current of the battery in the polarization state is determined based on the available voltage margin and the DC resistance. The power adjustment amount is determined based on the polarization current and the output voltage of the battery.
4. The method according to claim 1, characterized in that, The step of adjusting the actual discharge power of the battery based on the power adjustment amount to obtain the dynamic discharge power includes: The dynamic discharge power is obtained by superimposing the actual discharge power with the power adjustment amount.
5. The method according to claim 1, characterized in that, The step of controlling the battery discharge based on the static discharge power and the dynamic discharge power includes: The upper limit of the battery's discharge power is determined based on the smaller of the static discharge power and the dynamic discharge power. The battery discharge is controlled based on the upper limit of the discharge power.
6. The method according to claim 5, characterized in that, The method of controlling the battery discharge based on the upper limit of the discharge power includes: When the actual discharge power of the battery is less than or equal to the upper limit of the discharge power, the battery is controlled to discharge according to the actual discharge power. If the actual discharge power of the battery is greater than the upper limit of the discharge power, the battery is controlled to discharge according to the upper limit of the discharge power.
7. The method according to any one of claims 1 to 6, characterized in that, Obtain the battery's open-circuit voltage and DC resistance, including: The battery temperature and the state of charge of the battery are obtained. The open-circuit voltage and DC resistance of the battery are determined from a first relationship table and a second relationship table based on the battery temperature and the state of charge, respectively. The first relationship table includes the correlation between the battery temperature, the state of charge and the open-circuit voltage, and the second relationship table includes the correlation between the battery temperature, the state of charge and the DC resistance.
8. The method according to claim 7, characterized in that, Obtaining the state of charge of the battery includes: Obtain the output voltage of the battery; The initial state of charge of the battery is determined from a third relation table based on the output voltage and the battery temperature, wherein the third relation table includes the correlation between the output voltage, the battery temperature and the state of charge; The state-of-charge correction value is obtained by integrating the output current of the battery in ampere-hours. The initial state of charge is corrected based on the state of charge correction value to obtain the state of charge of the battery.
9. A battery management system, characterized in that, include: Data acquisition equipment is used to collect the battery's open-circuit voltage, DC resistance, and discharge cutoff voltage. The processor is configured to: determine the static discharge power of the battery based on the open-circuit voltage, the DC resistance, and the discharge cutoff voltage, wherein the static discharge power characterizes the maximum power output by the battery in a non-polarized state; determine the power adjustment amount of the battery based on the minimum output voltage, the DC resistance, and the discharge cutoff voltage, wherein the power adjustment amount characterizes the additional power released by the battery when discharged to the discharge cutoff voltage in a polarized state; adjust the actual discharge power of the battery based on the power adjustment amount to obtain the dynamic discharge power; and control the battery discharge based on the static discharge power and the dynamic discharge power.
10. An electrical device, characterized in that, Includes a battery and the battery management system as described in claim 9.