Battery power calculation method, controller and energy storage device

Abstract

The invention discloses a battery electric quantity calculation method, a controller and an energy storage device, and the method comprises the steps: determining an accumulated freezing capacity based on an accumulated discharge capacity and a current temperature value; calculating the residual total capacity according to the accumulated discharge capacity, the accumulated freezing capacity and the normal-temperature total capacity; calculating residual available capacity and residual freezing capacity according to the residual total capacity and the current temperature value; calculating the total capacity of the current state based on the normal-temperature total capacity, the accumulated freezing capacity and the residual freezing capacity; and calculating the battery power based on the residual available capacity and the current state total capacity. The problem of how to improve the accuracy of estimating the electric quantity value of the battery in a low-temperature and high-low-temperature switching scene is solved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery power calculation method, a controller, and an energy storage device. Background Art

[0002] With the rapid development of new energy vehicles and energy storage systems, lithium iron phosphate batteries (LiFePO4) are widely used in power batteries and energy storage batteries due to their excellent cycle life and safety performance. The battery's state of charge (SOC), a core parameter for measuring the remaining charge, is directly related to battery safety, endurance, and the operation strategy of the battery management system (BMS).

[0003] Currently, battery companies often use the following two typical SOC estimation methods: one is to quickly convert between normal temperature SOC and low temperature SOC through a preset mapping relationship; the other is based on the ampere-hour integration method, directly reducing the low temperature capacity by a preset low temperature capacity retention rate for calculation. The second conventional SOC estimation method is implemented based on the following calculation formula:

[0004]

[0005] Q0 is equal to the product of the total capacity at room temperature and the capacity retention rate;

[0006] Among them, SOC i is the power value at time i, SOC j is the charge value at time j, Q0 is the total capacity of the battery in the current state, Q0 is equal to the product of the total capacity at room temperature and the capacity retention rate. The capacity retention rate refers to the ratio of the charge value of the battery when it is fully charged at the current temperature value to the charge value of the battery when it is fully charged at room temperature.

[0007] However, the battery's SOC estimation has obvious temperature correlation. Usually, the total capacity that can be discharged at low temperature has a fixed proportional relationship with the total capacity at room temperature, which is called the capacity retention rate. The capacity retention rate changes with temperature, and the capacity that cannot be discharged is called frozen capacity. When the battery is in a low temperature environment or experiences rapid switching between high and low temperatures, the mapping relationship method cannot dynamically reflect the changes in the actual available capacity of the battery at different temperatures and different discharge rates, which can easily cause SOC estimation lag or over-correction. Especially in scenarios where high and low temperatures are frequently switched, the SOC estimation error is significant. SOC in the ampere-hour integration method i It cannot be updated according to the capacity retention rate at the current temperature, which may lead to the battery discharge capacity being underestimated or overestimated when the temperature changes, affecting the energy utilization rate. Moreover, if only the temperature changes and the battery does not discharge, the ampere-hour integration method cannot reflect the change in the actual available capacity of the power value.

[0008] Therefore, how to improve the accuracy of estimating battery power values ​​in low-temperature and high-low-temperature switching scenarios has always been a technical problem that the industry has focused on.

[0009] The above information disclosed in this Background section is included only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the relevant art that is currently known to a person of ordinary skill in the art. Summary of the Invention

[0010] The present application provides a battery power calculation method, a controller, and an energy storage device to solve the problem of how to improve the accuracy of estimating battery power values ​​in low-temperature and high-low temperature switching scenarios.

[0011] This application adopts the following technical solution.

[0012] In a first aspect, the present application provides a battery power calculation method, a controller, and an energy storage device method, including: determining a cumulative frozen capacity based on a cumulative discharge capacity and a current temperature value;

[0013] Calculate the remaining total capacity based on the cumulative discharge capacity, cumulative frozen capacity, and total capacity at room temperature;

[0014] Calculate the remaining available capacity and remaining frozen capacity based on the remaining total capacity and the current temperature value;

[0015] Calculate the total capacity in the current state based on the total capacity at room temperature, the accumulated frozen capacity, and the remaining frozen capacity;

[0016] The battery capacity is calculated based on the remaining available capacity and the current total capacity.

[0017] In practical applications, this application divides the total capacity at room temperature into four parts: cumulative discharge capacity, cumulative frozen capacity, remaining available capacity and remaining frozen capacity, and calculates the values ​​of these four parts in real time based only on the current temperature value, thereby obtaining a more real and accurate capacity status, so that the battery power can dynamically reflect the actual impact of the current temperature change on the battery capacity.

[0018] Compared with the existing technology, this application does not rely on comparative calculations before and after temperature changes, nor does it adopt a fixed mapping relationship or a correction method for static capacity retention rate. Instead, it estimates the remaining frozen capacity based entirely on the current temperature value, updates the remaining available capacity and the current state total capacity based on the remaining frozen capacity, and calculates the battery power at the current temperature based on the definition of battery power, thereby effectively eliminating the error introduced by the historical temperature value before the temperature change. It can more realistically and accurately reflect the actual state of the battery power after the temperature change, and significantly improve the accuracy of battery power estimation. This application can solve the problem of excessively hiding capacity when the temperature switches in the related technology. When the temperature switches, the frozen capacity can be intelligently adjusted to improve the customer's battery life experience according to the instantaneous scene temperature. It can adapt to different working conditions and application scenarios, covering all-weather and full temperature changes.

[0019] In conjunction with the first aspect, in one possible implementation, determining the cumulative frozen capacity based on the cumulative discharge capacity and the current temperature value includes:

[0020] The cumulative frozen capacity is determined according to the capacity retention rate and the cumulative discharge capacity, wherein the capacity retention rate is determined according to the current temperature value.

[0021] Related technologies often have the problem of estimating frozen capacity based on historical temperature conditions, which can easily lead to battery power calculation lags or error accumulation. This application determines the capacity retention rate in real time based on the current temperature value, and uses the capacity retention rate and cumulative discharge capacity to update the cumulative frozen capacity. This ensures that the cumulative frozen capacity is dynamically updated based entirely on the current temperature environment and is not affected by historical temperatures. This allows the cumulative frozen capacity to truly and accurately reflect the battery's capacity frozen state at the current temperature in real time, avoiding interference from the historical capacity retention rate on the current battery power calculation.

[0022] In conjunction with the first aspect, in one possible implementation, the cumulative frozen capacity is determined according to the capacity retention rate determined by the current temperature value and the cumulative discharge capacity, and is implemented based on the following calculation formula:

[0023]

[0024] Among them, Q frz,acc is the cumulative frozen capacity, Q dis,acc is the cumulative discharge capacity, CR T is the capacity retention rate.

[0025] This calculation formula is to calculate how much capacity is frozen in the total capacity at room temperature in order to release the cumulative discharge capacity according to the discharge capacity allowed by the current temperature value. Specifically, Indicates how many units of capacity are frozen for every unit of discharge capacity released at the current temperature.

[0026] It can also be understood as represents the sum of the cumulative discharge capacity and the cumulative freezing capacity, The accumulated frozen capacity is the sum of the accumulated discharge capacity and the accumulated frozen capacity.

[0027] In conjunction with the first aspect, in one possible implementation, calculating the remaining available capacity and the remaining frozen capacity based on the remaining total capacity and the current temperature value includes:

[0028] The remaining available capacity and the remaining frozen capacity are calculated based on the capacity retention rate determined by the current temperature value and the remaining total capacity.

[0029] In conjunction with the first aspect, in one possible implementation, the remaining available capacity and the remaining frozen capacity are calculated based on the capacity retention rate and the remaining total capacity, where the capacity retention rate is determined based on the current temperature value, including:

[0030] Multiply the remaining total capacity and the capacity retention rate to obtain the remaining available capacity;

[0031] The remaining frozen capacity is obtained by subtracting the product of the remaining total capacity and the capacity retention rate from the remaining total capacity.

[0032] Real-time updates of the remaining available capacity more accurately reflect the battery's currently available capacity. The remaining frozen capacity refers to the theoretically frozen portion of the remaining capacity that is being released based on the discharge capacity allowed by the current temperature.

[0033] In combination with the first aspect, in one possible implementation, the capacity retention rate is positively correlated with the temperature value.

[0034] In conjunction with the first aspect, in one possible implementation, calculating the remaining total capacity based on the cumulative discharged capacity, the cumulative frozen capacity, and the total capacity at room temperature includes:

[0035] Subtract the cumulative discharge capacity and the cumulative frozen capacity from the total capacity at room temperature to obtain the remaining total capacity.

[0036] Subtracting the cumulative discharged capacity and the cumulative frozen capacity from the room-temperature total capacity yields the remaining total capacity. This clearly establishes a direct quantitative relationship between the room-temperature total capacity, the cumulative discharged capacity, the cumulative frozen capacity, and the remaining total capacity. This calculation method provides a clear and logically rigorous process for calculating the remaining total capacity.

[0037] In conjunction with the first aspect, in one possible implementation, calculating the total capacity in the current state based on the total capacity at room temperature, the accumulated frozen capacity, and the remaining frozen capacity includes:

[0038] Subtract the accumulated frozen capacity and the remaining frozen capacity from the total capacity at room temperature to get the total capacity in the current state.

[0039] The current state total capacity is calculated by subtracting the accumulated frozen capacity and the remaining frozen capacity from the room temperature total capacity. This clarifies the quantitative relationship between the current state total capacity, the room temperature total capacity, the accumulated frozen capacity, and the remaining frozen capacity. This calculation method effectively ensures that the calculation of the current state total capacity fully accounts for all capacity that has been frozen and unavailable during battery operation, and truly reflects the actual total available capacity of the battery under current temperature conditions.

[0040] In a second aspect, the present application further provides an energy storage device. The energy storage device includes various modules for executing the battery power calculation method, controller, and energy storage device method in the first aspect or any optional implementation of the first aspect. For example, the energy storage device includes:

[0041] Temperature sampling module, obtains the current temperature value;

[0042] The controller is connected to the sampling output end of the temperature sampling module and is used to: determine the cumulative frozen capacity based on the cumulative discharge capacity and the current temperature value; calculate the remaining total capacity based on the cumulative discharge capacity, the cumulative frozen capacity, and the total capacity at room temperature; calculate the remaining available capacity and the remaining frozen capacity based on the remaining total capacity and the current temperature value; calculate the current state total capacity based on the total capacity at room temperature, the cumulative frozen capacity, and the remaining frozen capacity; and calculate the battery power based on the remaining available capacity and the current state total capacity.

[0043] For more detailed implementation details of the energy storage device, please refer to the description of any implementation method in the first aspect above.

[0044] In a third aspect, the present application provides a controller comprising: a memory and a processor, wherein the memory is used to store computer instructions; and when the processor executes the computer instructions, the method of any one of claims 1 to 8 is implemented.

[0045] The beneficial effects of the second to third aspects above can be referred to the first aspect or any possible implementation of the first aspect, and will not be described in detail here. Based on the implementations provided in the above aspects, this application can also be further combined to provide more implementations.

[0046] Other advantages, objectives and features of the present application will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. 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 structures shown in these drawings without paying any creative work.

[0048] Figure 1 This is a flow chart of a battery power calculation method provided in an embodiment of the present application;

[0049] Figure 2 is a schematic structural diagram of the energy storage device provided in an embodiment of the present application;

[0050] Figure 3 A schematic diagram of the total capacity components at room temperature provided in an embodiment of the present application;

[0051] Figure 4 Schematic diagram for explaining capacity retention rate provided in the embodiments of the present application;

[0052] Figure 5 This is a schematic diagram provided in an embodiment of the present application for showing the change of the accumulated frozen capacity over time in working condition 1;

[0053] Figure 6 This is a schematic diagram provided in an embodiment of the present application for showing the change of battery power over time in working condition 1;

[0054] Figure 7 This is a schematic diagram provided in an embodiment of the present application for illustrating the change of the accumulated frozen capacity over time in working condition 2;

[0055] Figure 8 This is a schematic diagram provided in an embodiment of the present application for showing the change of battery power over time in working condition 2;

[0056] Figure 9 This is a schematic diagram provided in an embodiment of the present application for showing the change of the accumulated frozen capacity over time in working condition 3;

[0057] Figure 10 This is a schematic diagram provided in an embodiment of the present application for showing the change of battery power over time in working condition 3;

[0058] Figure 11 This is a schematic diagram provided in an embodiment of the present application for illustrating the change of the accumulated frozen capacity over time in working condition 4;

[0059] Figure 12 This is a schematic diagram provided in an embodiment of the present application for showing how the battery charge changes over time in operating condition 4. DETAILED DESCRIPTION

[0060] It should be noted that, in this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0061] Various circuits or other components may be described or referred to as being "configured to" perform one or more tasks. In this case, "configured to" is used to imply structure by indicating that the circuit / component includes structure (e.g., circuitry) that performs the one or more tasks during operation. Thus, even when a specified circuit / component is not currently operational (e.g., not turned on), the circuit / component may be referred to as being configured to perform the task. Circuits / components used with the phrase "configured to" include hardware, such as circuitry that performs an operation, etc.

[0062] Before introducing the embodiments of the present application, the technical terms and background technologies involved in the present application are first introduced.

[0063] Capacity retention rate: The ratio of a battery's total available capacity at its current temperature to its total available capacity at room temperature, typically around 25°C. Capacity retention rate reflects the impact of temperature on a battery's available capacity and is an important parameter for measuring a battery's discharge capacity at the current temperature.

[0064] Currently, battery companies often use the following two typical SOC estimation methods: Algorithm 1 uses a preset mapping relationship to quickly convert between normal temperature SOC and low temperature SOC; Algorithm 2 is based on the ampere-hour integration method and directly reduces the low temperature capacity by a preset low temperature capacity retention rate for calculation. The second conventional SOC estimation method is implemented based on the following calculation formula:

[0065]

[0066] Among them, SOC i is the power value at time i, SOC j is the charge value at time j, Q0 is the total capacity of the battery in the current state, Q0 is equal to the product of the total capacity at room temperature and the capacity retention rate. The capacity retention rate refers to the ratio of the charge value of the battery when it is fully charged at the current temperature value to the charge value of the battery when it is fully charged at room temperature.

[0067] However, the battery SOC estimation has obvious temperature dependence. Usually, the total capacity that can be discharged at low temperature has a fixed proportional relationship with the total capacity at room temperature, which is called the capacity retention rate. The capacity retention rate changes with temperature. Figure 4 , Figure 4The horizontal axis is the amount of electricity released during the discharge process at 25°C, the unit of the horizontal axis is Ah, the vertical axis is the remaining amount of electricity released during the discharge process at -20°C, and the slope is the capacity retention rate at -20°C. Take the point with the horizontal axis of 0 and the vertical axis of 81.59 as an example. Figure 4 The meaning is that in an environment of 25℃, the battery releases 0Ah of electricity in a fully charged state, then at -20℃, the battery can still release 81.59Ah of electricity.

[0068] When the battery is in a low-temperature environment or experiences rapid switching between high and low temperatures, the mapping relationship method cannot dynamically reflect the changes in the actual available capacity of the battery at different temperatures and discharge rates, which can easily cause SOC estimation lag or over-correction. In particular, in scenarios where high and low temperatures are frequently switched, the SOC estimation error is significant. i It cannot be updated according to the capacity retention rate at the current temperature, which may lead to the battery discharge capacity being underestimated or overestimated when the temperature changes, affecting the energy utilization rate. Moreover, if only the temperature changes and the battery does not discharge, the ampere-hour integration method cannot reflect the change in the actual available capacity of the power value.

[0069] In summary, the battery charge estimation methods in related technologies have the problem of low accuracy in estimating battery charge values ​​in low-temperature and high-low temperature switching scenarios. To address the above problem, the embodiments of the present application provide a battery charge calculation method that can improve the accuracy of estimating battery charge values ​​in low-temperature and high-low temperature switching scenarios.

[0070] The battery power calculation method provided in the embodiment of the present application is as follows: Figure 1 The figure is a flow chart of a battery power calculation method provided by an embodiment of the present application. The method of the present application can be applied to an energy storage device, and the energy storage device can refer to Figure 2 , including: a temperature sampling module 401 and a controller 402. The temperature sampling module 401 is used to obtain the current temperature value. The controller 402 is connected to the sampling output terminal of the temperature sampling module 401. The execution subject of the method of the present application can be the controller 402.

[0071] Before introducing the method of this application, we first introduce the classification of battery capacity in this application. Figure 3 This application divides the total capacity of the battery at room temperature into four parts: cumulative discharge capacity, cumulative frozen capacity, remaining available capacity and remaining frozen capacity. This application calculates the remaining available capacity and the total capacity in the current state, and then calculates the power based on the definition of power.

[0072] Reference Figure 1 , a battery power calculation method provided in an embodiment of the present application includes the following steps:

[0073] S101, determining a cumulative freezing capacity based on a cumulative discharge capacity and a current temperature value;

[0074] The cumulative discharge capacity refers to the total amount of electricity that has been released from the battery after one or more discharge processes starting from a fully charged state. The cumulative discharge capacity can be recorded in a timely manner by the controller 402 of the energy storage device during the charge and discharge management process.

[0075] As a possible implementation, the cumulative frozen capacity is determined based on the cumulative discharge capacity and the current temperature value, including: determining the capacity retention rate according to the current temperature value, and determining the cumulative frozen capacity according to the capacity retention rate and the cumulative discharge capacity. Specifically:

[0076]

[0077] Among them, Q frz,acc is the cumulative frozen capacity, Q dis,acc is the cumulative discharge capacity, CR T is the capacity retention rate.

[0078] The capacity retention rate can be obtained based on the mapping relationship between temperature and capacity retention rate. The capacity retention rate and temperature are positively correlated. This mapping relationship can be a function with temperature as the independent variable and capacity retention rate as the dependent variable. It can also be a table data storage of the capacity retention rates corresponding to different temperature values. Based on the temperature value, the capacity retention rate corresponding to the temperature value is obtained by looking up the table, as shown in Table 1. If the table does not contain the same temperature value as the current temperature value, the capacity retention rate corresponding to the current temperature value can be determined by interpolation when looking up the table.

[0079] Table 1 Temperature value-capacity retention rate correlation table

[0080] temperature Capacity retention rate [10,25) 95％ [-5,10) 85％ [-20,-5) 65％ [-35,-20) 45％

[0081] As shown in Table 1 above, the temperature value-capacity retention rate correlation table includes capacity retention rate correlation data corresponding to multiple temperature values, where temperature value is positively correlated with capacity retention rate. The capacity retention rate reflects the impact of temperature on the battery's available capacity.

[0082] Related technologies often have the problem of estimating frozen capacity based on historical temperature conditions, which can easily lead to battery power calculation lags or error accumulation. This application determines the capacity retention rate in real time based on the current temperature value, and uses the capacity retention rate and cumulative discharge capacity to update the cumulative frozen capacity. This ensures that the cumulative frozen capacity is dynamically updated based entirely on the current temperature environment and is not affected by historical temperatures. This allows the cumulative frozen capacity to truly and accurately reflect the battery's capacity frozen state at the current temperature in real time, avoiding interference from the historical capacity retention rate on the current battery power calculation.

[0083] The calculation formula (1) is to calculate how much capacity is frozen in the total capacity at room temperature in order to release the cumulative discharge capacity according to the discharge capacity allowed by the current temperature value, that is, the cumulative frozen capacity. The calculation formula can be understood in two ways. One is It means that at the current temperature value, for every unit of discharge capacity released, how many units of capacity are frozen. The product of this ratio and the cumulative discharge capacity is the cumulative frozen capacity. It can also be understood as represents the sum of the cumulative discharge capacity and the cumulative frozen capacity, What is obtained is the cumulative frozen capacity of the sum of the cumulative discharge capacity and the cumulative frozen capacity.

[0084] S103, calculating the remaining total capacity based on the cumulative discharge capacity, the cumulative frozen capacity, and the total capacity at room temperature;

[0085] As a possible implementation method, the remaining total capacity is calculated based on the cumulative discharge capacity, the cumulative frozen capacity, and the total capacity at room temperature, including: subtracting the cumulative discharge capacity and the cumulative frozen capacity from the total capacity at room temperature to obtain the remaining total capacity, that is:

[0086] Q rem =Q ref -Q dis,acc -Q frz,acc (2);

[0087] The remaining total capacity is obtained by subtracting the cumulative discharge capacity and the cumulative frozen capacity from the total capacity at room temperature. The direct quantitative relationship between the total capacity at room temperature, the cumulative discharge capacity, the cumulative frozen capacity and the remaining total capacity is clearly established. Formula (2) makes the calculation process of the remaining total capacity clear in structure and rigorous in logic.

[0088] S105, calculating the remaining available capacity and the remaining frozen capacity according to the remaining total capacity and the current temperature value;

[0089] The remaining available capacity refers to the effective capacity that the battery can currently discharge.

[0090] The remaining frozen capacity refers to the theoretical amount of capacity that is frozen in the remaining total capacity when all the remaining available capacity is released according to the discharge capacity allowed by the current temperature value.

[0091] The remaining total capacity refers to the sum of the remaining available capacity and the remaining frozen capacity.

[0092] As a possible implementation, the remaining available capacity and the remaining frozen capacity are calculated based on the capacity retention rate determined by the current temperature value and the remaining total capacity, including: multiplying the remaining total capacity and the capacity retention rate to obtain the remaining available capacity, and subtracting the product of the remaining total capacity and the capacity retention rate from the remaining total capacity to obtain the remaining frozen capacity, that is:

[0093] Q ava,rem =Q rem ×CR T (3);

[0094] Q frz,rem =Q rem ×(1-CR T )(4);

[0095] The capacity retention rate can be obtained based on the mapping relationship between temperature and capacity retention rate. The capacity retention rate and temperature are positively correlated. When the method is actually running, the capacity retention rate can be directly determined in step S101 without repeated calculation.

[0096] The remaining total capacity is the sum of the remaining available capacity and the remaining frozen capacity. The remaining available capacity refers to the battery's currently available capacity and can be calculated by multiplying the remaining total capacity by the capacity retention rate. The remaining frozen capacity refers to the theoretically frozen portion of the remaining total capacity that would be required to discharge the entire remaining available capacity based on the current temperature. This can be calculated by subtracting the remaining available capacity from the remaining total capacity (i.e., the remaining total capacity minus the product of the remaining total capacity and the capacity retention rate). Real-time updates of the remaining available capacity and remaining frozen capacity more accurately reflect the battery's currently available capacity.

[0097] S107, calculating the total capacity in the current state based on the total capacity at room temperature, the accumulated frozen capacity, and the remaining frozen capacity;

[0098] The current state total capacity refers to the total capacity of the battery after it is theoretically fully charged under the current temperature environment.

[0099] As a possible implementation method, the current state total capacity is calculated based on the total capacity at room temperature, the accumulated frozen capacity, and the remaining frozen capacity. This includes subtracting the accumulated frozen capacity and the remaining frozen capacity from the total capacity at room temperature to obtain the current state total capacity, that is:

[0100] Q cur =Q ref -Q frz,acc -Q frz,rem (5);

[0101] The current state total capacity refers to the total capacity of the battery after it is theoretically fully charged under the current temperature environment. Formula (5) clarifies the quantitative relationship between the current state total capacity and the total capacity at room temperature, the accumulated frozen capacity, and the remaining frozen capacity. This effectively ensures that the calculation process of the current state total capacity fully considers all capacity that has been frozen and unavailable during battery operation, and can truly reflect the actual total available capacity of the battery under the current temperature conditions.

[0102] S109: Calculate the battery capacity based on the remaining available capacity and the current total capacity.

[0103] As a possible implementation, the battery power is calculated based on the remaining available capacity and the current total capacity, including: dividing the remaining available capacity by the current total capacity to obtain the battery power, that is:

[0104]

[0105] This application divides the total capacity at room temperature into four parts: cumulative discharge capacity, cumulative frozen capacity, remaining available capacity and remaining frozen capacity, and calculates the values ​​of these four parts in real time based only on the current temperature value, thereby obtaining a more realistic and accurate capacity status, so that the battery power can dynamically reflect the actual impact of the current temperature change on the battery capacity.

[0106] Compared with the existing technology, this application does not rely on comparative calculations before and after temperature changes, nor does it adopt a fixed mapping relationship or a correction method for static capacity retention rate. Instead, it estimates the remaining frozen capacity based entirely on the current temperature value, updates the remaining available capacity and the current state total capacity based on the remaining frozen capacity, and calculates the battery power at the current temperature based on the definition of battery power, thereby effectively eliminating the error introduced by the historical temperature value before the temperature change. It can more realistically and accurately reflect the actual state of the battery power after the temperature change, and significantly improve the accuracy of battery power estimation. This application can solve the problem of excessively hiding capacity when the temperature switches in the related technology. When the temperature switches, the frozen capacity can be intelligently adjusted to improve the customer's battery life experience according to the instantaneous scene temperature. It can adapt to different working conditions and application scenarios, covering all-weather and full temperature changes.

[0107] For example, in a scenario where the battery is in a static state and the ambient temperature rises, the capacity retention rate increases with the increase of the current temperature value. Although the cumulative discharge capacity remains unchanged, the cumulative frozen capacity will decrease due to the increase in temperature because part of the capacity frozen due to low temperature is released again, resulting in an increase in the remaining total capacity. The remaining frozen capacity in the remaining total capacity will decrease because part of the capacity frozen due to low temperature is released again, and the remaining available capacity increases, which increases the total capacity in the current state and ultimately the battery power display increases.

[0108] For another example, when the ambient temperature rises and the battery continues to discharge, because the ambient temperature and battery charge are positively correlated, the discharge process causes the battery charge to decrease. Therefore, the battery charge may increase, decrease, or remain unchanged. The change in battery charge in this case depends on the relative relationship between discharge consumption and the release of frozen capacity. Specifically, first, the ambient temperature rise causes a portion of the accumulated frozen capacity and the remaining frozen capacity to be released to the remaining available capacity, thereby causing the battery charge to increase. However, during the discharge process, the remaining available capacity in the current state total capacity is consumed, increasing the cumulative discharge capacity. At the same time, due to the low temperature, the capacity retention rate is less than 1, causing the current state total capacity to decrease due to the partial freezing of the capacity. Therefore, as can be seen from S109, the remaining available capacity (the numerator) and the current state total capacity (the denominator) are both decreasing. Therefore, the change in battery charge may occur in three scenarios: increase, decrease, or remain unchanged. If the amount of charge released due to the ambient temperature rise is greater than the amount of charge consumed during the discharge process, the battery charge increases; conversely, the battery charge decreases. If the amount of charge released due to the ambient temperature rise is equal to the amount of charge consumed during the discharge process, the battery charge remains unchanged.

[0109] By the same token, if the ambient temperature drops and the battery continues to discharge, the battery capacity will definitely decrease, because the decrease in ambient temperature causes the battery capacity to decrease, and the discharge process also causes the battery capacity to decrease.

[0110] This method is illustrated by taking an example. First, based on the test data, the low temperature can be stratified by linear interpolation, with each 1°C, 2°C, 3°C, 5°C, 10°C, and 15°C being a layer. Here, the temperature values ​​are divided into four layers, with each layer being 15°C. The relationship between the temperature value and the capacity retention rate is shown in Table 2, where a%>b%>c%>d%.

[0111] Table 2 Temperature value-capacity retention rate correlation table

[0112] Capacity hidden layer temperature Capacity retention rate one [10,25) a％ two [-5,10) b％ three [-20,-5) c％ Four [-35,-20) d％

[0113] Assume four working conditions:

[0114] Working condition 1:

[0115] 1) From 0s to 2000s, maintain the temperature at -5°C and discharge at a constant current of 1 / 3C. During this process, the capacity of A1 and A4 in the first and second layers is frozen;

[0116] 2) At 2000s, the temperature drops to -20°C. The frozen capacity increases by A8 based on 1). That is, at 2000s, the frozen capacity changes to A2, A5, and A8.

[0117] 3) 2000s to 4000s, maintain the temperature at -20℃, and discharge at a constant current of 1 / 3C. Since the temperature does not change during this process, the frozen parts are still A2, A5 and A8;

[0118] 4) At 4000s, the temperature drops to -35°C. The frozen capacity at this time increases by A12 based on 3). That is, at 4000s, the frozen capacity changes to A3, A6, A9, and A12.

[0119] 5) 4000s ~ 9000s, maintain the temperature at -35℃, and discharge at a constant current of 1 / 3C until the battery is exhausted. Since the temperature does not change during this process, the frozen parts are still A3, A6, A9 and A12.

[0120] Cumulative frozen capacity changes over time as shown in Figure 5 As shown, from 0s to 2000s, the capacity of A1 and A4 on the first and second layers is frozen; at 2000s, due to the temperature drop, part of the capacity is frozen, resulting in the frozen capacity changing to A2, A5 and A8; from 2000s to 4000s, since the temperature does not change, the frozen part is still A2, A5 and A8; at 4000s, due to the temperature drop, part of the capacity is frozen, resulting in the frozen capacity changing to A3, A6, A9 and A12; from 4000s to 9000s, since the temperature does not change, the frozen part is still A3, A6, A9 and A12.

[0121] The battery charge changes over time. Figure 6 As shown. Figure 6 It can be seen that the battery power suddenly dropped at 2000s and 4000s, which means that the battery power suddenly dropped due to the sudden drop in temperature and the sudden increase in the accumulated frozen capacity.

[0122] Working condition 2:

[0123] 1) From 0s to 2000s, maintain the temperature at -5°C and discharge at a constant current of 1 / 3C;

[0124] 2) The temperature was reduced to -35°C at 2000s;

[0125] 3) 2000s to 4000s, maintain the temperature at -35°C, and discharge at a constant current of 1 / 3C;

[0126] 4) The temperature was raised to -20°C at 4000s;

[0127] 5) 4000s ~ 9000s, maintain the temperature at -20℃, and discharge at a constant current of 1 / 3C until the battery is exhausted.

[0128] Cumulative frozen capacity changes over time as shown in Figure 7 As shown, from 0s to 2000s, the capacity of A1 and A4 on the first and second layers is frozen; at 2000s, due to the temperature drop, part of the capacity is frozen, resulting in the frozen capacity changing to A2, A5, A8 and A11; from 2000s to 4000s, since the temperature does not change, the frozen part remains A2, A5, A8 and A11; at 4000s, due to the temperature rise, part of the frozen capacity is released, resulting in the frozen capacity changing to A3, A6 and A9; from 4000s to 9000s, since the temperature does not change, the frozen part remains A3, A6 and A9.

[0129] The battery charge changes over time. Figure 8 As shown in the figure, the battery power suddenly drops at 2000s, indicating that the accumulated frozen capacity suddenly increases due to a sudden drop in temperature, leading to a sudden drop in battery power. The battery power suddenly increases at 4000s, indicating that part of the accumulated frozen capacity is suddenly released due to a sudden rise in temperature, leading to a sudden increase in battery power.

[0130] Working condition 3:

[0131] 1) From 0s to 2000s, maintain the temperature at -35°C and discharge at a constant current of 1 / 3C;

[0132] 2) The temperature was raised to -20°C at 2000s;

[0133] 3) 2000s to 4000s, maintain the temperature at -20℃, and discharge at a constant current of 1 / 3C;

[0134] 4) The temperature was raised to -5°C at 4000s;

[0135] 5) 4000s ~ 9000s, maintain the temperature at -5℃, and discharge at a constant current of 1 / 3C until the battery is exhausted.

[0136] Cumulative frozen capacity changes over time as shown in Figure 9As shown, from 0s to 2000s, the capacities of A1, A4, A7, and A10 of the first, second, third, and fourth layers are frozen; at 2000s, due to the temperature increase, part of the frozen capacity is released, resulting in the frozen capacity changing to A2, A5, and A8; from 2000s to 4000s, since the temperature does not change, the frozen part remains A2, A5, and A8; at 4000s, due to the temperature increase, part of the frozen capacity is released, resulting in the frozen capacity changing to A3 and A6; from 4000s to 9000s, since the temperature does not change, the frozen part remains A3 and A6.

[0137] The battery charge changes over time. Figure 10 As shown in the figure, the battery charge suddenly dropped at 2000s, indicating that due to the sudden temperature rise, part of the accumulated frozen capacity was suddenly released, resulting in a sudden increase in the battery charge. At 4000s, the battery charge suddenly increased, indicating that due to the sudden temperature rise, part of the accumulated frozen capacity was suddenly released, resulting in a sudden increase in the battery charge.

[0138] Working condition 4:

[0139] 1) From 0s to 2000s, maintain the temperature at -35°C and discharge at a constant current of 1 / 3C;

[0140] 2) The temperature was raised to -5°C at 2000s;

[0141] 3) 2000s to 4000s, maintain the temperature at -5°C, and discharge at a constant current of 1 / 3C;

[0142] 4) The temperature was reduced to -20°C at 4000s;

[0143] 5) 4000s ~ 9000s, maintain the temperature at -20℃, and discharge at a constant current of 1 / 3C until the battery is exhausted.

[0144] Cumulative frozen capacity changes over time as shown in Figure 11 As shown, from 0s to 2000s, the capacities of A1, A4, A7, and A10 of the first, second, third, and fourth layers are frozen; at 2000s, due to the temperature increase, part of the frozen capacity is released, resulting in the frozen capacity changing to A2 and A5; from 2000s to 4000s, since the temperature does not change, the frozen part remains A2 and A5; at 4000s, due to the temperature drop, part of the capacity is frozen, resulting in the frozen capacity changing to A3, A6, and A9; from 4000s to 9000s, since the temperature does not change, the frozen part remains A3, A6, and A9.

[0145] The battery charge changes over time. Figure 12 As shown in the figure, the battery power suddenly dropped at 2000s, indicating that due to the sudden increase in temperature, part of the accumulated frozen capacity was suddenly released, resulting in a sudden increase in the battery power. At 4000s, the battery power suddenly increased, indicating that due to the sudden decrease in temperature, the accumulated frozen capacity suddenly increased, resulting in a sudden drop in the battery power.

[0146] In order to illustrate the difference between the present application and the related art, the following assumes a situation in which the battery power is calculated using the algorithm in the related art and the algorithm of the present application respectively.

[0147] Condition 5: The total capacity of the battery at room temperature is 100Ah, the initial SOC of the battery is 100%, and the capacity retention rate at a temperature of -50°C is 0.85;

[0148] 1) Discharge the battery for 50 Ah at room temperature;

[0149] 2) Discharge the battery for 35 Ah at a temperature of -50°C.

[0150] Algorithm 1: Rapid conversion between normal temperature SOC and low temperature SOC through a preset mapping relationship.

[0151] In the initial state, SOC0=100%;

[0152] 1) SOC1=100%-50Ah / 100Ah=50%;

[0153] 2) SOC ′ 2=50%-35Ah / 100Ah=15%. The actual SOC mapped by SOC2 obtained according to the preset mapping relationship is 0%.

[0154] Algorithm 2: Based on the ampere-hour integration method, the low-temperature capacity is directly reduced by the preset low-temperature capacity retention rate for calculation.

[0155] In the initial state, SOC0=100%;

[0156] 1) SOC1=100%-50Ah / 100Ah=50%;

[0157] 2) SOC2=50%-35Ah / (100Ah×0.85)=8.82%.

[0158] Algorithm 3: The algorithm of this application.

[0159] In the initial state, SOC0 = 100%;

[0160] 1) SOC1=(100Ah-50Ah) / 100Ah=50%;

[0161] 2) SOC2=(50Ah×0.85-35Ah) / [100Ah-50Ah×(1-0.85)]=8.1%.

[0162] In summary, the amount of electricity calculated by Algorithm 3 of the present application is quite different from that calculated by Algorithm 1 and Algorithm 2 in the related art.

[0163] Based on the same technical concept, the embodiment of the present application also claims protection for an energy storage device, referring to Figure 2 , including: a temperature sampling module 401 and a controller 402.

[0164] The temperature sampling module 401 is used to obtain the current temperature value;

[0165] The controller 402 is connected to the sampling output end of the temperature sampling module 401 and is used to: determine the cumulative frozen capacity based on the cumulative discharge capacity and the current temperature value; calculate the remaining total capacity based on the cumulative discharge capacity, the cumulative frozen capacity, and the total capacity at room temperature; calculate the remaining available capacity and the remaining frozen capacity based on the remaining total capacity and the current temperature value; calculate the current state total capacity based on the total capacity at room temperature, the cumulative frozen capacity, and the remaining frozen capacity; and calculate the battery power based on the remaining available capacity and the current state total capacity.

[0166] The energy storage device can be a battery module, a battery pack, an energy storage battery cabinet, an energy storage container, a UPS power supply device, or other types of energy storage systems. When the energy storage device is a battery module, the temperature sampling module 401 is preferably a thermistor temperature sensor, a digital temperature sensor, or a small infrared temperature sensor, and the controller 402 is preferably a microcontroller unit (MCU) or a battery management system submodule. When the energy storage device is a battery pack, the temperature sampling module 401 is preferably a thermistor temperature sensor, a thermocouple, or a digital temperature sensor, and the controller 402 is preferably a battery management system main control unit or an electronic control unit (ECU). When the energy storage device is an energy storage battery cabinet or an energy storage container, the temperature sampling module 401 is preferably a thermistor temperature sensor or a fiber optic temperature sensor, and the controller 402 is preferably an industrial programmable controller or an energy storage system integrated main control unit.

[0167] For more details, please refer to the method embodiment section, which will not be repeated here.

[0168] Based on the same concept, the present application also requests protection for a controller 402, which includes a memory and a processor, the memory is used to store computer instructions; when the processor executes the computer instructions, the above method is implemented. The specific implementation process can be found in the description of the above method embodiment, which will not be repeated here.

[0169] It should be noted that the order of description of the embodiments of the present application does not limit the priority order of the embodiments.

[0170] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0171] It should be noted that the “connected” or “connected” mentioned in this application, unless otherwise specified, not only includes directly connecting two entities, but also includes indirectly connecting through other entities with beneficial improvement effects.

[0172] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims. All equivalent transformations made by using the contents of the description and drawings of this application under the inventive concept of this application, or direct / indirect application in other related technical fields are included in the scope of patent protection of this application.

Claims

1. A method for calculating battery power, characterized in that: include: Determining the cumulative freezing capacity based on the cumulative discharge capacity and the current temperature value; Calculating the remaining total capacity according to the cumulative discharge capacity, the cumulative frozen capacity, and the total capacity at room temperature; Calculating the remaining available capacity and the remaining frozen capacity according to the remaining total capacity and the current temperature value; Calculating the total capacity in the current state based on the total capacity at room temperature, the accumulated frozen capacity, and the remaining frozen capacity; The battery power is calculated based on the remaining available capacity and the current total capacity.

2. The battery capacity calculation method according to claim 1, characterized in that: The step of determining the accumulated frozen capacity based on the accumulated discharge capacity and the current temperature value includes: The cumulative frozen capacity is determined based on the capacity retention rate determined by the current temperature value and the cumulative discharge capacity.

3. The battery capacity calculation method according to claim 2, characterized in that: The cumulative frozen capacity is determined according to the capacity retention rate and the cumulative discharge capacity, wherein the capacity retention rate is determined according to the current temperature value, and is implemented based on the following calculation formula: Among them, Q frz,acc is the cumulative frozen capacity, Q dis,acc is the cumulative discharge capacity, CR T is the capacity retention rate.

4. The battery capacity calculation method according to claim 1, characterized in that: The calculating the remaining available capacity and the remaining frozen capacity according to the remaining total capacity and the current temperature value includes: The remaining available capacity and the remaining frozen capacity are calculated according to the capacity retention rate determined by the current temperature value and the remaining total capacity.

5. The battery power calculation method according to claim 4, characterized in that: The calculating the remaining available capacity and the remaining frozen capacity according to the capacity retention rate and the remaining total capacity, wherein the capacity retention rate is determined according to the current temperature value, includes: Multiplying the remaining total capacity by the capacity retention rate to obtain the remaining available capacity; The remaining frozen capacity is obtained by subtracting the product of the remaining total capacity and the capacity retention rate from the remaining total capacity.

6. The battery power calculation method according to any one of claims 2 or 4, characterized in that: The capacity retention rate is positively correlated with the temperature value.

7. The battery capacity calculation method according to claim 1, characterized in that: The calculating of the remaining total capacity according to the cumulative discharge capacity, the cumulative frozen capacity, and the total capacity at room temperature includes: The remaining total capacity is obtained by subtracting the cumulative discharge capacity and the cumulative frozen capacity from the room temperature total capacity.

8. The battery capacity calculation method according to claim 1, characterized in that: The calculating of the current state total capacity based on the normal temperature total capacity, the accumulated frozen capacity, and the remaining frozen capacity includes: The total capacity at the current state is obtained by subtracting the accumulated frozen capacity and the remaining frozen capacity from the total capacity at room temperature.

9. A controller, characterized in that: The method comprises a memory and a processor, wherein the memory is used to store computer instructions; when the processor executes the computer instructions, the method according to any one of claims 1 to 8 is implemented.

10. An energy storage device, characterized in that: include: Temperature sampling module, obtains the current temperature value; A controller connected to the sampling output terminal of the temperature sampling module, configured to determine the accumulated freezing capacity based on the accumulated discharge capacity and the current temperature value; Calculate the remaining total capacity based on the cumulative discharge capacity, the cumulative frozen capacity, and the total capacity at room temperature; calculate the remaining available capacity and the remaining frozen capacity based on the remaining total capacity and the current temperature value; Calculating the total capacity in the current state based on the total capacity at room temperature, the accumulated frozen capacity, and the remaining frozen capacity; The battery power is calculated based on the remaining available capacity and the current total capacity.

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