Method and device for determining charge state of energy storage equipment and energy storage equipment

Abstract

The embodiment of the invention provides an energy storage equipment charge state determination method and device and energy storage equipment, and the energy storage equipment charge state determination method comprises the steps: determining that the energy storage equipment enters a low-temperature working condition based on the power storage voltage of the energy storage equipment; under the condition that the energy storage equipment enters the low-temperature working condition, it is determined that the electricity storage voltage goes through a wave trough to a wave crest along with time change; determining the charge state of the energy storage equipment by using an ampere-hour integral method before the change of the electricity storage voltage along with time does not pass through the wave peak; and determining the charge state of the energy storage equipment by utilizing dynamic compensation correction based on the current power storage voltage and the current temperature of the energy storage equipment and the current current rate of the energy storage equipment after the change of the power storage voltage with time passes through the peak. According to the scheme of the invention, the influence of the temperature on the SOC estimation can be considered under the condition that the calculation amount is not large, and the accuracy of the SOC estimation of the energy storage device is improved.

Description

Technical Field

[0001] This application belongs to the field of energy storage, specifically relating to a method, apparatus and energy storage device for determining the state of charge of an energy storage device. Background Technology

[0002] With the development of renewable energy, the demand for energy storage devices (such as new energy batteries) is increasing, and the state of charge (SOC) of these devices directly affects system performance. Temperature changes affect the capacity and internal resistance of energy storage devices, leading to inaccurate SOC estimation. Currently, the SOC of energy storage devices is generally estimated using the correlation between voltage and SOC, but this method does not consider the influence of temperature, resulting in poor accuracy. The extended Kalman filter method offers high accuracy and considers temperature compensation, but it involves a large computational burden. Summary of the Invention

[0003] The purpose of this application is to provide a method, apparatus, and energy storage device for determining the state of charge (SOC) of an energy storage device, which can consider the influence of temperature on SOC estimation with a small computational load, thereby improving the accuracy of SOC estimation for the energy storage device.

[0004] To achieve the above objectives, an embodiment of the first aspect of this application provides a method for determining the state of charge (SOC) of an energy storage device, comprising: determining that the energy storage device has entered a cryogenic operating condition based on its stored voltage; determining that the stored voltage changes from a trough to a peak over time when the energy storage device has entered a cryogenic operating condition; determining the SOC of the energy storage device using the ampere-hour integral method before the stored voltage changes over time has completed the peak; and determining the SOC of the energy storage device using dynamic compensation correction based on the current stored voltage, current temperature, and current current ratio of the energy storage device after the stored voltage changes over time has completed the peak.

[0005] An embodiment of the second aspect of this application provides a device for determining the state of charge (SOC) of an energy storage device, comprising: a first determining unit for determining that the energy storage device has entered a cryogenic operating condition based on its stored voltage; a second determining unit for determining that, when the energy storage device has entered a cryogenic operating condition, the change in stored voltage over time has gone through a trough to a peak; a third determining unit for determining the SOC of the energy storage device using an ampere-hour integral method before the change in stored voltage over time has gone through a peak; and a fourth determining unit for determining the SOC of the energy storage device using dynamic compensation correction based on the current stored voltage, current temperature, and current current ratio of the energy storage device after the change in stored voltage over time has gone through a peak.

[0006] An embodiment of the third aspect of this application provides an energy storage device, including a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the steps of the energy storage device state of charge determination method as described in the first aspect.

[0007] This application, through extensive experiments, discovered that when an energy storage device discharges at low temperatures, the voltage curve exhibits a trough effect due to the increased internal resistance of the device. This is followed by a peak, and the curve only returns to normal after the peak. Traditional dynamic compensation correction methods can be used to estimate the State of Charge (SOC) based on the voltage. Therefore, this application first determines whether the energy storage device has entered a low-temperature operating condition based on its stored voltage. After confirming the entry into the low-temperature operating condition, this application further determines whether the stored voltage experiences a trough followed by a peak. Before the peak is fully experienced, it is considered a stage where the internal resistance of the energy storage device is significantly affected by temperature at low temperatures, and the SOC is determined using the ampere-hour integration method. After the peak is fully experienced, it is considered a stage where the internal resistance of the energy storage device does not change significantly, and dynamic compensation correction is used to estimate the SOC. This method significantly reduces the computational load compared to the extended Kalman filter method and fully considers the influence of temperature on the internal resistance of the energy storage device at low temperatures when estimating the SOC, thus improving estimation accuracy while reducing computational load.

[0008] Additional aspects and advantages of the technical solutions of this application will become apparent in the following description or may be learned by practice of this application. Attached Figure Description

[0009] Figure 1 A flowchart illustrating a method for determining the state of charge of an energy storage device according to an embodiment of this application is shown.

[0010] Figure 2 This is a schematic diagram of cryogenic discharge in one embodiment of this application;

[0011] Figure 3 Here is a specific flowchart for step S110;

[0012] Figure 4 Here is a specific flowchart for step S120;

[0013] Figure 5 Here is a specific flowchart for step S130;

[0014] Figure 6 This is a two-dimensional graph of temperature-current ratio according to one embodiment of this application;

[0015] Figure 7a A flowchart illustrating a specific embodiment of the method for determining the state of charge of an energy storage device according to this application is shown;

[0016] Figure 7bA flowchart illustrating a specific embodiment of the method for determining the state of charge of an energy storage device according to this application is shown;

[0017] Figure 8 A schematic block diagram of the structure of the energy storage device state of charge determination device according to this application is shown;

[0018] Figure 9 A schematic block diagram of the energy storage device according to this application is shown. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of the embodiments of this application, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods. It should be noted that, unless otherwise specified, the embodiments of this application and the features within them can be combined with each other.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, embodiments of this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0021] The method, apparatus and energy storage device for determining the state of charge of energy storage devices provided in this application will be described in detail below with reference to specific embodiments and application scenarios.

[0022] like Figure 1 As shown, according to one embodiment of this application, a method for determining the state of charge of an energy storage device is provided. The method includes:

[0023] Step S100: Based on the energy storage voltage of the energy storage device, determine whether the energy storage device has entered the low-temperature operating condition;

[0024] Among them, energy storage equipment refers to devices used to store electrical energy. Specifically, energy storage equipment may include new energy batteries, which have the function of storing electrical energy and need to correct the state of charge (SOC) estimation results based on parameters such as voltage, current, and temperature.

[0025] Energy storage voltage refers to the voltage present inside or at both ends of an energy storage device during the process of storing or releasing electrical energy. The specific energy storage voltage can be obtained through periodic sampling or real-time detection, and is used for subsequent threshold comparison and status assessment.

[0026] Low-temperature operating conditions refer to the operating state in which the electrical characteristics of energy storage devices change significantly due to low temperatures. Under this operating state, the traditional correlation between voltage and state of charge becomes invalid, and different methods need to be used in stages to estimate the state of charge (SOC) to ensure accuracy.

[0027] Specifically, users can detect the energy storage voltage and determine whether the energy storage device is in a low-temperature operating condition based on the degree of change in the energy storage voltage. The specific determination method is described in detail in the embodiments described later, and will not be repeated here.

[0028] Step S110: When the energy storage device enters the low-temperature operating condition, determine the change of the energy storage voltage over time from the trough to the peak.

[0029] Specifically, when an energy storage device enters a low-temperature operating condition, its stored voltage exhibits a unique time-varying pattern during discharge, first decreasing to a trough and then rising to a peak due to the increased internal resistance caused by the low temperature. For example... Figure 2 As shown, due to differences in cell performance and battery pack operating conditions, this phenomenon may occur 1 to 3 times during low-temperature discharge. Clearly, in the trough voltage range, there is no good mapping relationship between voltage and SOC; calibrating SOC using voltage during this stage will produce significant errors.

[0030] Step S120: Before the change in energy storage voltage over time has completed its peak, determine the state of charge of the energy storage device using the ampere-hour integration method;

[0031] Since the energy storage voltage is still fluctuating due to low temperature before the peak is completed, the internal resistance of the energy storage device is greatly affected by temperature. Traditional voltage-based dynamic compensation correction cannot accurately estimate the state of charge. Therefore, the ampere-hour integration method is required to calculate the state of charge.

[0032] Specifically, the ampere-hour integration method is as follows:

[0033] SOC(k+1)=SOC(k)+η×Isamp×Δt / Qmax;

[0034] Where SOC(k+1) is the ampere-hour integral SOC at the current moment, SOC(k) is the ampere-hour integral SOC at the previous moment, η is the coulomb efficiency, which is obtained through experimental testing and has a value range of 0.99 < η < 1, Isamp is the sampling current at the current moment, Δt is the single-step sampling time, and Qmax is the maximum capacity of the current battery state.

[0035] Step S130: After the energy storage voltage has gone through the peak of the change over time, the state of charge of the energy storage device is determined by dynamic compensation correction based on the current energy storage voltage, current temperature and current ratio of the energy storage device.

[0036] In this process, after the voltage change over time reaches its peak, it transitions from a period of violent fluctuations to a stable phase. The voltage fluctuation amplitude decreases after the peak, and its correlation with SOC (State of Charge) stabilizes. It is understandable that due to factors such as current measurement errors at low temperatures and capacity decay, the ampere-hour integration method has accumulated certain errors during the trough-to-peak phase, requiring correction through voltage correlation correction.

[0037] This application, through extensive experiments, has discovered that when an energy storage device discharges at low temperatures, the voltage curve exhibits a trough effect due to the increased internal resistance of the device. This is followed by a peak, and the curve only returns to normal after the peak. Traditional dynamic compensation correction methods can be used to estimate the State of Charge (SOC) based on the voltage. Therefore, this disclosure first determines whether the energy storage device has entered a low-temperature operating condition based on its stored voltage. After confirming the entry into the low-temperature operating condition, it then determines whether the stored voltage experiences a trough followed by a peak. Before the peak is fully experienced, it is considered a stage where the internal resistance of the energy storage device is significantly affected by temperature at low temperatures, and the SOC is determined using the ampere-hour integration method. After the peak is fully experienced, it is considered a stage where the internal resistance of the energy storage device does not change significantly, and dynamic compensation correction is used to estimate the SOC. This method significantly reduces the computational load compared to the extended Kalman filter method and fully considers the influence of temperature on the internal resistance of the energy storage device at low temperatures when estimating the SOC, thus improving estimation accuracy while reducing computational load.

[0038] In one embodiment, step S100 may specifically include the following steps S1001 to S1003:

[0039] Step S1001: The energy storage voltage is detected to be lower than the first voltage threshold, wherein the first voltage threshold is the voltage critical point at which the energy storage device enters the low-temperature operating condition;

[0040] The first voltage threshold refers to a pre-set voltage boundary value used to determine whether the energy storage device has initially met the conditions for entering cryogenic operating conditions. This detection is a preliminary step in determining cryogenic operating conditions, and it can be achieved by collecting the energy storage voltage of the energy storage device in real time or periodically and comparing it with the first voltage threshold.

[0041] Specifically, if the stored voltage is not lower than the first voltage threshold, the device is determined not to meet the conditions for entering low-temperature operating conditions, and no further steps are required. If the stored voltage is lower than the first voltage threshold, it indicates that the device may experience changes in electrical performance due to the low temperature, such as an increase in internal resistance leading to a voltage drop, requiring further testing.

[0042] Step S1002: Obtain the first duration for which the stored voltage remains below the first voltage threshold;

[0043] The first duration refers to the continuous time during which the energy storage voltage remains below the first voltage threshold after the energy storage device is detected to be below the first voltage threshold for the first time.

[0044] Specifically, the starting point of the first duration is determined when the stored voltage is first detected to be lower than a first voltage threshold. This can be achieved by immediately activating the timing function, such as triggering a timer to begin counting. This initial detection moment is the starting point for the first duration.

[0045] Specifically, starting from the beginning of the timing, the stored voltage is continuously collected. The collection method can be real-time collection, comparing the currently collected stored voltage with a first voltage threshold in real time.

[0046] Step S1003: If the first duration is greater than the first duration threshold, determine that the energy storage device has entered the low temperature operating condition.

[0047] The first duration threshold is a pre-set minimum duration standard used to distinguish between occasional voltage fluctuations and sustained electrical performance changes caused by low temperatures. It is understood that the first duration threshold is calibrated based on the low-temperature characteristics of the energy storage device. For example, experimental data shows that only when the voltage is below the first threshold for more than 30 seconds is it considered a stable electrical performance change caused by low temperatures, rather than a transient disturbance.

[0048] Understandably, during continuous voltage acquisition, in one possible scenario, the current voltage may rise to a level greater than or equal to the first voltage threshold. In this case, since the first duration is the continuous period during which the voltage remains below the first voltage threshold, the continuity of the first duration is interrupted once the voltage rises. Therefore, it is necessary to restart the timing from the next time the voltage is first detected to be below the first voltage threshold, and continuously repeat the process of acquiring the first duration until a node is reached to determine whether the first duration is greater than the first duration threshold.

[0049] Specifically, the first duration is compared with the first duration threshold. If the first duration is greater than the first duration threshold, it can be determined that the energy storage device has entered the low-temperature operating condition.

[0050] In this embodiment, the energy storage voltage is detected to be below a first voltage threshold. In the process of determining whether an energy storage device has entered a cryogenic operating condition, the energy storage voltage value is first determined. This detection is the primary preliminary step in determining a cryogenic operating condition, and it initially screens potential cryogenic operating conditions. The first duration for which the energy storage voltage remains below the first voltage threshold is obtained. After the energy storage voltage of the energy storage device is detected to be below the first voltage threshold for the first time, the continuous duration of the energy storage voltage is continuously detected and counted. The first duration is compared with the first duration threshold to finally determine that the energy storage device has entered a cryogenic operating condition, ensuring that the determination is of the continuous change in electrical performance caused by the low temperature, rather than a temporary voltage anomaly.

[0051] like Figure 3 As shown, in one embodiment, step S110 may specifically include the following S1101 to S1104:

[0052] Step S1101: When the energy storage device enters a low-temperature operating condition, determine the extreme voltage of the energy storage voltage trough;

[0053] Among them, the trough extreme voltage is the lowest stable voltage value reached under low temperature conditions.

[0054] It should be noted that after entering the low-temperature operating condition, the energy storage voltage will continue to decrease due to the increase in internal resistance. Therefore, it is necessary to determine the lowest stable voltage that appears after the energy storage voltage continues to decrease through standardized testing to avoid misjudging instantaneous voltage fluctuations as troughs.

[0055] Step S1102: In response to the occurrence of a trough extreme voltage in the energy storage voltage, determine the end of the trough phase;

[0056] The trough phase refers to the complete range from the drop in energy storage voltage to the extreme trough voltage, and then to the stable recovery and escape from the trough.

[0057] Specifically, the end of the trough phase is determined on the premise that the extreme voltage of the trough has already occurred.

[0058] Step S1103: Determine the peak voltage of the energy storage voltage;

[0059] Among them, peak voltage refers to the highest stable voltage value reached by the energy storage voltage after it recovers from the trough under low temperature conditions.

[0060] Specifically, this highest value can be accurately captured through standardized testing, avoiding misjudging the instantaneous voltage peak as a wave peak.

[0061] Step S1104: In response to the occurrence of peak voltage after the storage voltage reaches its extreme value, determine that the peak phase has ended.

[0062] The peak phase refers to the complete range from the trough of the energy storage voltage to the peak voltage, and then to the stable decline away from the peak.

[0063] Specifically, the end of the peak phase is determined when the peak voltage has already occurred.

[0064] In this embodiment, when the energy storage device enters a low-temperature operating condition, the system identifies the lowest voltage trough and accurately captures this minimum value to avoid misinterpreting instantaneous voltage fluctuations as troughs. Then, in response to the occurrence of the lowest voltage trough, the system determines the end of the trough phase and the transition to the peak phase. Conversely, it identifies the highest voltage peak and accurately captures this maximum value to avoid misinterpreting instantaneous voltage peaks as peaks. After the highest voltage peak, the system determines the end of the peak phase. This signifies that the energy storage voltage has transitioned from a fluctuating phase to a normal variation phase. At this point, the internal resistance of the energy storage device tends to stabilize due to temperature influences, and the logic of traditional voltage-related state of charge (SOC) can be combined with compensation correction.

[0065] In one embodiment, step S1101 may specifically include the following steps S1101a to S1101c:

[0066] Step S1101a: Set the first reference value to the trough detection start voltage, which is greater than the trough extreme voltage;

[0067] The first reference value is a baseline variable used to track the lowest value of the energy storage voltage. It should be noted that the first reference value is not initially set to an arbitrary voltage, but rather uses the trough detection start voltage as its initial value, and will be updated subsequently based on changes in the real-time energy storage voltage.

[0068] Specifically, it updates only when the current stored voltage is less than the first reference value, ensuring that it always points to the lowest voltage up to the present.

[0069] The trough detection start-up voltage is a reference voltage used to trigger trough extreme voltage tracking. It should be noted that the trough extreme voltage is the lowest possible voltage drop in the energy storage system under low-temperature conditions, and the trough detection start-up voltage must be at least greater than the trough extreme voltage. For example, if the trough extreme voltage of the energy storage device at low temperatures is 2.8V, its trough detection start-up voltage can be preset to 3.0V.

[0070] Specifically, the first reference value is set as the trough detection start voltage, and this value is greater than the trough extreme voltage. This is a prerequisite for accurately capturing the trough extreme voltage in the future.

[0071] Step S1101b: After the stored voltage is less than the trough detection start voltage, continuously compare the stored voltage with the first reference value. If the stored voltage is less than the first reference value, update the first reference value with the stored voltage.

[0072] It should be noted that when the stored voltage is lower than the trough detection start voltage, it means that the stored voltage has entered the stage of continuously decreasing towards the trough extreme voltage. Only at this time is it necessary to start tracking the lowest voltage to avoid invalid calculations before the voltage has entered the decreasing stage.

[0073] Specifically, after the stored voltage first falls below the trough detection start voltage, the current stored voltage is collected, either in real time or at a preset sampling period, and the collected stored voltage is compared with the current first reference value.

[0074] In one possible scenario, if the current energy storage voltage is greater than or equal to the current first reference value, it indicates that the voltage has not continued to decrease or has slightly rebounded. In this case, the first reference value will not be updated, and its current value will remain unchanged.

[0075] Specifically, when the current energy storage voltage is lower than the current first reference value, it means that the energy storage voltage is still decreasing and a voltage lower than the previously recorded lowest value has appeared. In this case, the current energy storage voltage can replace the original first reference value so that the first reference value is always kept at the lowest energy storage voltage value up to the present.

[0076] Step S1101c: If the first reference value remains unchanged for the second duration threshold, determine that the energy storage voltage has a trough extreme voltage, wherein the trough extreme voltage is the value at which the first reference value remains unchanged.

[0077] Specifically, when the first reference value, i.e. the lowest voltage currently being tracked, remains unchanged for a duration that reaches the second duration threshold, it indicates that the energy storage voltage has stopped decreasing and has entered a stable state. At this point, it can be determined that the first reference value that remains unchanged is the extreme voltage of the energy storage voltage under low temperature conditions, marking that the energy storage voltage has officially dropped to the lowest value of the trough stage.

[0078] In this embodiment, a first reference value is set as the trough detection start voltage, and this value is greater than the trough extreme voltage. This provides a clear initial comparison standard for subsequent comparison steps. The currently collected energy storage voltage is compared with the current first reference value to determine the instantaneous minimum value during the energy storage voltage decline process in real time. When the first reference value, i.e., the currently tracked minimum voltage, remains unchanged for a duration reaching a second duration threshold, it indicates that the energy storage voltage has stopped declining and entered a stable state. This step eliminates interference from the voltage continuing to decline after a brief pause, ensuring that the captured first reference value is the true trough minimum voltage.

[0079] In one embodiment, step S1102 may specifically include the following steps S1102a to S1102c:

[0080] Step S1102a: Calculate the trough end voltage based on the trough extreme voltage and the first voltage increment, where the first voltage increment is the voltage increment required to leave the trough stage;

[0081] The first voltage increment is the voltage increment required to escape the trough stage, which can be pre-calibrated to ensure the minimum effective amplitude of voltage recovery.

[0082] Specifically, after the energy storage device enters the low-temperature operating condition and the extreme voltage of the trough is determined, the lowest value of the energy storage voltage under the low-temperature operating condition is used as a benchmark, and a minimum voltage recovery amplitude is superimposed to meet the requirements for leaving the trough stage. The superposition method can be addition, and the trough end voltage is obtained through addition. This voltage is used to determine whether the energy storage voltage has stably left the trough.

[0083] Step S1102b: Periodically collect the stored voltage and record the number of the first cycles in which the stored voltage is continuously greater than the end voltage of the trough;

[0084] Periodic acquisition refers to continuously acquiring real-time values ​​of the stored voltage at preset fixed time intervals. For example, the stored voltage is acquired every 5 seconds.

[0085] The first cycle number refers to the number of cycles used to count consecutive compliance cycles.

[0086] Specifically, the real-time value of the stored voltage can be continuously collected at preset fixed time intervals, and the collection results can be judged. If the currently collected stored voltage is greater than the previously calculated trough end voltage, the first cycle count can be accumulated.

[0087] In one possible scenario, if the currently collected energy storage voltage is less than or equal to the trough end voltage, the first cycle count can be reset to zero and the count can be repeated.

[0088] Specifically, the number of the first cycle recorded is the number of sampling cycles in which the stored voltage continuously meets the requirement of being greater than the end voltage of the trough, thus avoiding interference from single voltage fluctuations.

[0089] Step S1102c: If the number of the first cycle is greater than the threshold of the number of the first cycle, the trough phase is determined to be over.

[0090] The first cycle number threshold refers to the minimum continuous cycle standard used to determine whether the voltage has stabilized and moved out of the trough.

[0091] Specifically, after periodically collecting the stored voltage and recording the number of the first cycles in which the stored voltage is continuously greater than the end voltage of the trough, the actual number of the first cycles is compared with the preset threshold number of the first cycles.

[0092] If the value of the first cycle number is greater than the threshold of the first cycle number, it indicates that the energy storage voltage has stabilized and rebounded and continues to move away from the voltage range of the trough stage. At this point, the end of the trough stage can be officially determined.

[0093] In this embodiment, the trough end voltage is calculated based on the trough extreme voltage and the first voltage increment. Only when the stored voltage rises and exceeds the trough end voltage is the initial condition for leaving the trough stage met. The stored voltage is periodically sampled, and the number of consecutive cycles in which the stored voltage is greater than the trough end voltage is recorded. Periodic sampling avoids interference from single voltage fluctuations, and recording the number of consecutive cycles ensures that the voltage rise is a stable trend. If the number of the first cycle is greater than the first cycle threshold, the trough stage is determined to have ended, indicating that the stored voltage has steadily risen and continuously moved away from the voltage range of the trough stage. At this point, the end of the trough stage can be formally confirmed. Occasional fluctuations in the stored voltage, such as a single or short-term rise above the trough end voltage followed by a drop, are excluded to ensure the reliability of the determination result.

[0094] In one embodiment, step S1103 may specifically include the following steps S1103a to S1103c:

[0095] Step S1103a: Set the second reference value to the peak detection start voltage, which is less than the peak extreme voltage;

[0096] Step S1103b: After the stored voltage is greater than the peak detection start voltage, continuously compare the stored voltage with the second reference value. If the stored voltage is greater than the second reference value, update the second reference value with the stored voltage.

[0097] Step S1103c: If the second reference value remains unchanged for a third duration threshold, determine that the energy storage voltage has a peak extreme voltage, wherein the peak extreme voltage is the value at which the second reference value remains unchanged.

[0098] In this embodiment, the principle of the steps is the same as that of S1101a to S1101c, and will not be repeated here. A second reference value is set as the peak detection start voltage, and this value is less than the peak extreme voltage, providing a clear initial comparison standard for subsequent comparison steps. The currently collected energy storage voltage is compared with the current second reference value to determine the instantaneous highest value during the energy storage voltage recovery process in real time. When the second reference value, i.e., the currently tracked highest voltage, remains unchanged for a duration reaching a second duration threshold, it indicates that the energy storage voltage has stopped recovering and entered a stable state. This step eliminates interference from the voltage continuing to rise after a brief pause, ensuring that the captured second reference value is the true peak minimum voltage.

[0099] In one embodiment, step S1104 may specifically include the following S1104a to S1104c:

[0100] Step S1104a: Calculate the peak end voltage based on the peak extreme voltage and the first voltage reduction, where the first voltage reduction is the voltage reduction required to leave the peak stage;

[0101] Step S1104b: Periodically collect the stored voltage and record the number of the second period in which the stored voltage is continuously greater than the peak end voltage;

[0102] Step S1104c: If the number of the second cycle is greater than the threshold of the number of the second cycle, the peak phase is determined to be over.

[0103] In this embodiment, the principle of the steps is the same as that of S1102a to S1102c, and will not be repeated here. In this embodiment, based on the trough extreme voltage and the first voltage reduction, the peak end voltage is calculated. Only when the energy storage voltage drops and exceeds the peak end voltage can the preliminary conditions for leaving the peak stage be met. The energy storage voltage is periodically collected, and the number of the second period in which the energy storage voltage is continuously less than the peak end voltage is recorded. Periodic collection avoids interference from single voltage fluctuations, and recording the number of consecutive periods that meet the standard ensures that the voltage drop is a stable trend. If the number of the second period is greater than the second period threshold, the peak stage is determined to have ended, indicating that the energy storage voltage has steadily decreased and continuously left the voltage range of the peak stage. At this time, the end of the fluctuation stage can be formally determined.

[0104] like Figure 4 As shown, in one embodiment, step S120 may specifically include the following S1201 to S1203:

[0105] Step S1201: Obtain the current sampling current, sampling period interval, current maximum capacity of the energy storage device, and state of charge of the energy storage device in the previous sampling period obtained from sampling the energy storage device in the current sampling period;

[0106] Step S1202: Calculate the state of charge increment based on the current sampling current, sampling period interval, and current maximum capacity;

[0107] Step S1203: Based on the state of charge and state of charge increment of the previous sampling period, determine the state of charge of the energy storage device in the current sampling period.

[0108] In one embodiment, step S1202 may specifically include the following steps S1202a to S1202c:

[0109] Step S1202a: Perform discharge capacity tests on the energy storage device at predetermined test intervals;

[0110] The predetermined test time interval refers to a fixed test cycle. It can be set in advance according to hourly, daily, or specific operating condition cycles, such as every 24 hours, or after 10 charge-discharge cycles. This ensures the regularity of the test and the comparability of the data, avoiding misjudgments of performance changes caused by random testing.

[0111] Specifically, standardized tests are performed periodically on energy storage devices, either by full discharge or a specific depth of discharge, to measure the actual amount of electricity that can be released.

[0112] Step S1202b: For every two adjacent test time points, fit a straight line to the curve of discharge capacity changing with time to obtain a fitted piecewise linear curve of discharge capacity over time.

[0113] It should be noted that multiple sets of discrete data can be obtained by pre-determined test intervals. Each set of data includes test time points, such as day 1, day 7, and day 14, and corresponding discharge capacities, such as 100 amp-hours, 98 amp-hours, and 85 amp-hours. These data are represented as isolated points in the time and capacity coordinate system.

[0114] Specifically, a time-capacity coordinate system can be established, and all test data points can be marked on the coordinate system according to time. Every two adjacent test time points can be connected by straight lines. After all adjacent data points are connected, a continuous broken line composed of multiple straight lines can be obtained, which is the fitting broken line of discharge capacity over time.

[0115] Step S1202c: Based on the fitted piecewise linear curve, obtain the maximum capacity of the current state.

[0116] Among them, the current maximum capacity is the maximum amount of electricity that the energy storage device can actually release at the current time, under the current capacity decay rate and current operating conditions.

[0117] Specifically, the discrete test data has been transformed into a continuous relationship between time and capacity based on the fitted piecewise linear interpolation. Therefore, the maximum capacity at any time point can be obtained through piecewise linear interpolation without additional testing.

[0118] Specifically, the fitting relationship between temperature and battery capacity is defined as follows:

[0119] T<=T(0), Qmax(T) = Qmax(T(0));

[0120] T>=T(n),Qmax(T) = Qmax(T(n));

[0121] T(0) < T <T(n),Qmax(T) = K×T+b;

[0122] Where K = [Qmax(T(k))-Qmax(T(k-1))] / (T(k)-T(k-1));

[0123] b=[Qmax(T(k-1))×T(k)- Qmax(T(k))×T(k-1)] / (T(k)-T(k-1));

[0124] Where T(0)~T(n) are temperature test points, their coverage and interval can be dynamically adjusted according to the available range of battery temperature and the accuracy requirements of the algorithm;

[0125] The capacity obtained by discharging capacity test at the temperature test point is Qmax(T(0))~Qmax(T(n)); T is the actual temperature of the current battery. The resolution is adjusted in the range of 0.1℃~1℃ depending on the accuracy requirements. Regarding the value of k, it is required that k-1<=T<=k, and k-1>=0, k<=n.

[0126] In this embodiment, the energy storage device is subjected to discharge capacity testing at predetermined test intervals. For every two adjacent test time points, a straight line is fitted to the curve of discharge capacity changing with time to obtain a fitted piecewise linear curve of discharge capacity over time. Periodic testing yields isolated data points, which may be affected by single test errors. Therefore, this application transforms the discrete point values ​​into continuous fitted piecewise linear curves. By reading the corresponding values ​​of the fitted piecewise linear curves, the discharge capacity between time points can be quickly obtained without additional testing.

[0127] like Figure 5 As shown, in one embodiment, step S130 may specifically include the following S1301 to S1304:

[0128] Step S1301: Obtain the reference voltage lookup table corresponding to each of the multiple reference states of charge. The reference voltage lookup table indicates the reference voltage under the combination of multiple reference current multipliers and multiple reference temperatures.

[0129] Specifically, the current ratio, temperature, and voltage data corresponding to each reference SOC can be organized in a two-dimensional table format.

[0130] The reference voltage lookup table refers to a two-dimensional data table for a single reference SOC. Typically, the horizontal axis represents the reference current ratio, such as 0.1, 0.5, or 1, which is the ratio of discharge current to rated capacity. The vertical axis represents the reference temperature, such as -20℃, -10℃, 0℃…25℃. The value in each cell of the table is the reference voltage of the energy storage device at the corresponding reference SOC under that combination of current ratio and temperature.

[0131] Step S1302: Among multiple reference states of charge, determine the target state of charge that is closest to the state of charge of the energy storage device in the previous sampling period;

[0132] Specifically, from multiple pre-defined reference states of charge (SOCs), the value that is closest to the actual state of charge of the energy storage device in the previous sampling period is selected as the target state of charge, which can be determined by minimizing the absolute difference between the values.

[0133] Step S1303: In the reference voltage lookup table corresponding to the target state of charge, find the target voltage corresponding to the combination of the current temperature and the current current ratio;

[0134] Specifically, based on the determined target state of charge, its dedicated reference voltage lookup table is invoked. Then, according to the current actual temperature and actual current ratio of the energy storage device, the cell corresponding to the combination of the two in the table is located. The voltage value in that cell is the target voltage.

[0135] For example, using the above example where the horizontal axis represents current ratio, the vertical axis represents temperature, and the cell represents reference voltage, the actual ambient temperature of the energy storage device is the vertical axis locating condition. The actual current ratio of the energy storage device during discharge / charge is the horizontal axis locating condition. The search result is the standard reference voltage corresponding to the target state of charge under the current temperature and current ratio combination.

[0136] Step S1304: If the current energy storage voltage reaches the target voltage, determine the state of charge of the energy storage device as the target state of charge.

[0137] In this step, the current actual stored voltage of the energy storage device is compared with the target voltage. Specifically, the current actual stored voltage reaches the target voltage, meaning it matches the target voltage or meets a preset error range. Then, the target state of charge (SOC) is determined as the current SOC of the energy storage device. Specifically, at the end of charging / discharging, the voltage and SOC have a good mapping relationship, and this voltage can be used for SOC calibration. The voltage at this point is defined as the trigger voltage; that is, once the voltage reaches the trigger voltage, the SOC reaches the SOC mapped by that trigger voltage. A series of voltage-SOC mapping points can be established during charging and discharging; these points are defined as dynamic correction points. Assume there are n dynamic correction points during charging (SOCdc1, Vdc1), (SOCdc2, Vdc2), ..., (SOCdc1, Vdcn) and m dynamic correction points during discharging (SOCdc1, Vdc1), (SOCdc2, Vdc2), ..., (SOCdc1, Vdcm), where SOCdc is defined as the dynamic correction SOC and Vdc is defined as the dynamic correction trigger voltage. Vdci at each mapping point is a two-dimensional table relating temperature and current ratio, calibrated from charge / discharge test data. For example, a graph showing the SOCdci at a given dynamic correction point and its corresponding voltage Vdci is shown below. Figure 6 As shown, to determine whether a certain dynamic correction point is triggered, firstly, the voltage [temperature, current ratio] two-dimensional table to be looked up is determined through the mapping relationship (SOCdci, Vdci). Then, the trigger voltage Vdci is obtained by looking up the voltage [temperature, current ratio] two-dimensional table. Finally, by comparing the relationship between the current voltage and the trigger voltage, it is determined whether the current dynamic correction point is triggered.

[0138] Specifically, to obtain the accurate trigger voltage Vdc, the lookup table values ​​are refined. Assuming the current temperature is T, the corresponding index is Tindex, and the current multiplier corresponds to the index Cindex. The four lookup table values ​​are denoted as follows:

[0139] V11 = V[Tindex, Cindex];

[0140] V21 = V[Tindex+1, Cindex];

[0141] V12 = V[Tindex, Cindex + 1];

[0142] V22 = V[Tindex+1,Cindex+1];

[0143] Let Tindex correspond to temperature T1, Tindex+1 correspond to temperature T2, Cindex correspond to leverage C1, and Cindex+1 correspond to leverage C2. The calculated Vdc is:

[0144] Vdc=V11+(V21-v11)×(T-T1) / (T2-T1)+(V22-V21-V21+V11)×(T-T1) / (T2-T1)×(C-C1) / (C2-C1);

[0145] It should be noted that, for ease of expression, Vdc can be written as Lut(T,C).

[0146] Where Lut is a lookup table, representing the voltage value corresponding to temperature T and multiplier C calculated using the above interpolation formula.

[0147] In this embodiment, a reference voltage lookup table corresponding to each of the multiple reference states of charge is obtained. The reference voltage lookup table indicates the reference voltage under the combination of multiple reference current ratios and multiple reference temperatures. Among the multiple reference states of charge, the target state of charge that is closest to the state of charge of the energy storage device in the previous sampling period is determined. In the reference voltage lookup table corresponding to the target state of charge, the target voltage corresponding to the combination of the current temperature and the current current ratio is found. If the current energy storage voltage reaches the target voltage, the state of charge of the energy storage device is determined as the target state of charge. By matching the actual voltage with the standard voltage, the current SOC is calibrated with a precise reference SOC (target state of charge) to avoid error accumulation.

[0148] In one embodiment, step S1301 may specifically include the following steps S1301a to S1301c:

[0149] Step S1301a: If the current temperature is between the first reference temperature and the second reference temperature among multiple reference temperatures, and the current current multiplier is between the first reference current multiplier and the second reference current multiplier among multiple reference current multipliers, in the reference voltage lookup table, find the first reference voltage corresponding to the combination of the first reference temperature and the first reference current multiplier, wherein the first reference temperature is less than the second reference temperature, and the first reference current multiplier is less than the second reference current multiplier.

[0150] Step S1301b: Calculate the first voltage correction amount based on the first reference temperature, the second reference temperature, the first reference voltage, the second reference voltage, and the current temperature, wherein the second reference voltage is the reference voltage corresponding to the combination of the second reference temperature and the first reference current multiplier;

[0151] Step S1301c: Calculate the second voltage correction amount based on the first reference temperature, the second reference temperature, the first reference current multiplier, the second reference current multiplier, the first reference voltage, the second reference voltage, the third reference voltage, and the fourth reference voltage, wherein the third reference voltage is the reference voltage corresponding to the combination of the first reference temperature and the second reference current multiplier, and the fourth reference voltage is the reference voltage corresponding to the combination of the second reference temperature and the second reference current multiplier.

[0152] In this embodiment, when the current temperature and current ratio do not precisely match the preset range of the reference voltage lookup table, but are between two adjacent reference values, the adjacent reference parameters are first locked, and then the voltage corresponding to the combination of the minimum reference temperature and the minimum reference current ratio is extracted, which is the first reference voltage. The range of the reference voltage lookup table is fixed, but the actual operating temperature and current ratio may be arbitrary. By locking the four adjacent reference parameters of the current operating condition, one of the base voltages is extracted as the first reference voltage to avoid reference voltage deviation due to range mismatch. Through linear interpolation, the voltage compensation amount corresponding to the current temperature is calculated, and according to the uniform temperature change law, the approximate voltage of the current temperature under the first reference current ratio is obtained. However, when the current ratio is between adjacent reference values, the influence of current needs to be further corrected. Through temperature weighting and current linear interpolation, the accurate correction amount in the current dimension is finally obtained. After being superimposed with the first voltage correction amount, the target voltage for any temperature and any current ratio operating condition can be accurately calculated.

[0153] Figure 7a and Figure 7b A flowchart of a specific embodiment of the method for determining the state of charge of an energy storage device according to this application is shown.

[0154] Step S2000: Determine whether initialization is complete;

[0155] If not, proceed to step S2001: reset the threshold and clear the duration;

[0156] If so, then execute step S2002: Set a first voltage threshold, wherein the first voltage threshold is the voltage critical point at which the energy storage device enters the low-temperature operating condition;

[0157] Step S2004: Determine whether the detected energy storage voltage is lower than the first voltage threshold;

[0158] If not, proceed to step S2005: reset the first duration;

[0159] If so, then execute step S2006: obtain the first duration for which the energy storage voltage remains below the first voltage threshold;

[0160] Step S2008: Determine whether the first duration of the first voltage threshold is greater than the first duration threshold;

[0161] If not, proceed to step S2009: Determine that the energy storage device has entered a non-cryogenic operating condition;

[0162] If yes, then proceed to step S2010: Determine that the energy storage device has entered a cryogenic operating condition;

[0163] Step S2012: Set the first reference value to the trough detection start voltage, wherein the trough detection start voltage is greater than the trough extreme voltage;

[0164] Step S2014: Determine whether the energy storage voltage is less than the trough detection start voltage;

[0165] If not, proceed to step S2015: continuously compare the stored voltage with the first reference value until the stored voltage is less than the first reference value;

[0166] If so, proceed to step S2016: update the first reference value with the stored voltage;

[0167] Step S2018: Determine whether the duration of the first reference value is greater than the second duration threshold;

[0168] If not, proceed to step S2019: Determine that the energy storage voltage has not reached a trough extreme voltage;

[0169] If yes, then proceed to step S2020: determine the trough extreme voltage of the energy storage voltage, wherein the trough extreme voltage is the value of the first reference value that remains unchanged;

[0170] Step S2022: Determine whether the stored voltage is greater than the trough extreme voltage and the first voltage increment;

[0171] If not, proceed to step S2023: reset the first cycle number;

[0172] If yes, then execute step S2024: record the number of the first cycle in which the stored voltage is continuously greater than the end voltage of the trough;

[0173] Step S2026: Determine whether the number of consecutive first cycles of the energy storage voltage is greater than the threshold number of first cycles;

[0174] If not, proceed to step S2027: determine if the trough phase has not ended;

[0175] If yes, proceed to step S2028: Determine the end of the trough phase;

[0176] Step S2030: Set the second reference value to the peak detection start voltage, wherein the peak detection start voltage is less than the peak extreme voltage;

[0177] Step S2032: Determine whether the energy storage voltage is greater than the peak detection start voltage;

[0178] If not, proceed to step S2033: continuously compare the stored voltage with the second reference value until the stored voltage is greater than the second reference value;

[0179] If so, proceed to step S2034: update the second reference value with the stored voltage;

[0180] Step S2036: Determine whether the duration of the second reference value is greater than the third duration threshold;

[0181] If not, proceed to step S2037: Determine that the energy storage voltage does not exhibit peak voltage.

[0182] If yes, then proceed to step S2038: determine the peak extreme voltage of the energy storage voltage, wherein the peak extreme voltage is the value of the second reference value that remains unchanged.

[0183] Step S2040: Determine whether the stored voltage is less than the peak voltage and the first voltage reduction;

[0184] If not, proceed to step S2041: reset the second cycle number;

[0185] If so, proceed to step S2042: record the number of the second cycle in which the stored voltage is continuously greater than the peak end voltage;

[0186] Step S2044: Determine whether the number of consecutive second cycles of the energy storage voltage is greater than the threshold number of second cycles;

[0187] If not, proceed to step S2045: determine that the peak phase has not ended;

[0188] Step S2048: Before the change in energy storage voltage over time has completed its peak, determine the state of charge of the energy storage device using the ampere-hour integration method;

[0189] If so, proceed to step S2046: Determine the end of the peak phase;

[0190] Step S2050: After the energy storage voltage has gone through its peak over time, the state of charge of the energy storage device is determined by dynamic compensation correction based on the current energy storage voltage, current temperature, and current current ratio of the energy storage device.

[0191] In this embodiment, through extensive experiments, this application discovered that when an energy storage device discharges at low temperatures, the voltage curve exhibits a trough effect due to the increased internal resistance of the energy storage device at low temperatures, followed by a peak. Only after the peak ends does it return to a normal curve. Traditional dynamic compensation correction methods can be used to estimate the State of Charge (SOC) based on the voltage. Therefore, this application first determines whether the energy storage device has entered a low-temperature operating condition based on its stored voltage. After determining that it has entered a low-temperature operating condition, this application further determines whether the stored voltage experiences a trough before a peak. Before the peak is fully experienced, it is considered to be in a stage where the internal resistance of the energy storage device is greatly affected by temperature at low temperatures, and the SOC is determined using the ampere-hour integration method. After the peak is fully experienced, it is considered to be in a stage where the internal resistance of the energy storage device does not change significantly, and dynamic compensation correction is used to estimate the SOC at this time. This method significantly reduces the computational load compared to the extended Kalman filter method and can fully consider the influence of temperature on the internal resistance of the energy storage device at low temperatures when estimating the SOC, improving estimation accuracy while reducing computational load.

[0192] like Figure 8 As shown in the figure, this application embodiment also provides an energy storage device state of charge determination device 600, including:

[0193] The first determining unit 602 is used to determine whether the energy storage device has entered a low-temperature operating condition based on the energy storage voltage of the energy storage device.

[0194] The second determining unit 604 is used to determine the change of the energy storage voltage over time from trough to peak when the energy storage device enters a low-temperature operating condition.

[0195] The third determining unit 606 is used to determine the state of charge of the energy storage device using the ampere-hour integration method before the change of the energy storage voltage over time has gone through the peak.

[0196] The fourth determining unit 608 is used to determine the state of charge of the energy storage device by using dynamic compensation correction based on the current energy storage voltage, current temperature and current current ratio of the energy storage device after the change of the energy storage voltage over time has gone through the peak.

[0197] In this embodiment, the energy storage device state of charge (SOC) determination device provided in this application is implemented. Through extensive experiments, this application has discovered that when an energy storage device discharges at low temperatures, the voltage curve exhibits a trough effect due to the increased internal resistance of the energy storage device at low temperatures, followed by a peak. Only after the peak ends does it enter the normal curve. Traditional dynamic compensation correction methods can be used to estimate the SOC based on the voltage. Therefore, this application first determines whether the energy storage device has entered a low-temperature operating condition based on the stored voltage. After determining that it has entered a low-temperature operating condition, this application further determines whether the stored voltage experiences a trough before a peak. Before the peak is fully experienced, it is considered to be in a stage where the internal resistance of the energy storage device is greatly affected by temperature at low temperatures, and the SOC is determined using the ampere-hour integration method. After the peak is fully experienced, it is considered to be in a stage where the internal resistance of the energy storage device does not change significantly, and dynamic compensation correction is used to estimate the SOC at this time. This method significantly reduces the computational load compared to the extended Kalman filter method and can fully consider the influence of temperature on the internal resistance of the energy storage device at low temperatures when estimating the SOC, improving estimation accuracy while reducing computational load.

[0198] Optionally, in the energy storage device state of charge determination device 600 provided in this application embodiment, the first determination unit 602 is specifically used for:

[0199] The energy storage voltage is detected to be lower than the first voltage threshold, where the first voltage threshold is the voltage critical point at which the energy storage device enters the low-temperature operating condition;

[0200] The first duration during which the stored voltage remains below a first voltage threshold is obtained;

[0201] If the first duration exceeds the first duration threshold, the energy storage device is determined to have entered a cryogenic operating condition.

[0202] Optionally, the energy storage device state of charge determination device 600 provided in this application embodiment further includes a second determination unit 604:

[0203] The fifth determining unit 610 is used to determine the extreme voltage of the energy storage voltage trough when the energy storage device enters the low temperature operating condition.

[0204] The sixth determining unit 612 is used to determine the end of the trough phase in response to the occurrence of the extreme voltage at the trough of the stored voltage.

[0205] The seventh determining unit 614 is used to determine the peak voltage of the energy storage voltage.

[0206] The eighth determining unit 616 is used to determine the end of the peak phase in response to the occurrence of the peak extreme voltage of the stored voltage.

[0207] Optionally, in the energy storage device state of charge determination device 600 provided in this application embodiment, the fifth determination unit 610 is specifically used for:

[0208] The first reference value is set to the trough detection start voltage, which is greater than the trough extreme voltage.

[0209] After the stored voltage is lower than the trough detection start voltage, the stored voltage is continuously compared with the first reference value. If the stored voltage is lower than the first reference value, the first reference value is updated with the stored voltage.

[0210] If the first reference value remains unchanged for a second duration threshold, it is determined that the energy storage voltage has reached a trough extreme voltage, where the trough extreme voltage is the value at which the first reference value remains unchanged.

[0211] Optionally, in the energy storage device state of charge determination device 600 provided in this application embodiment, the sixth determination unit 612 is specifically used for:

[0212] Based on the trough extreme voltage and the first voltage increment, the trough end voltage is calculated, where the first voltage increment is the voltage increment required to leave the trough stage.

[0213] The stored voltage is periodically sampled, and the number of cycles in which the stored voltage is continuously greater than the end voltage of the trough is recorded.

[0214] If the number of the first cycle is greater than the threshold number of the first cycle, the trough phase is considered to have ended.

[0215] Optionally, in the energy storage device state of charge determination device 600 provided in this application embodiment, the seventh determination unit 614 is specifically used for:

[0216] The second reference value is set to the peak detection start voltage, which is less than the peak extreme voltage.

[0217] After the stored voltage is greater than the peak detection start voltage, the stored voltage is continuously compared with the second reference value. If the stored voltage is greater than the second reference value, the second reference value is updated with the stored voltage.

[0218] If the second reference value remains unchanged for a third duration threshold, it is determined that the energy storage voltage has a peak extreme voltage, where the peak extreme voltage is the value at which the second reference value remains unchanged.

[0219] Optionally, in the energy storage device state of charge determination device 600 provided in this application embodiment, the eighth determination unit 616 is specifically used for:

[0220] Based on the peak extreme voltage and the first voltage reduction, the peak end voltage is calculated, where the first voltage reduction is the voltage reduction required to leave the peak stage.

[0221] The stored voltage is periodically sampled, and the number of the second period in which the stored voltage is continuously greater than the peak end voltage is recorded.

[0222] If the number of the second cycle is greater than the threshold number of the second cycle, the peak phase is considered to have ended.

[0223] Optionally, the third determining unit 606 of the energy storage device state of charge determination device 600 provided in this application embodiment further includes:

[0224] The ninth determining unit 618 is used to obtain the current sampling current, sampling period interval, current maximum capacity of the energy storage device, and state of charge of the energy storage device in the previous sampling period obtained by sampling the energy storage device in the current sampling period.

[0225] The tenth determining unit 620 is used to calculate the state of charge increment based on the current sampling current, sampling period interval, and current maximum capacity.

[0226] The eleventh determining unit 622 is used to determine the state of charge of the energy storage device in the current sampling period based on the state of charge and the state of charge increment of the previous sampling period.

[0227] Optionally, in the energy storage device state of charge determination device 600 provided in this application embodiment, the ninth determination unit 618 is specifically used for:

[0228] Discharge capacity tests were conducted on the energy storage equipment at predetermined test intervals.

[0229] For every two adjacent test time points, a straight line is fitted to the curve of discharge capacity changing with time to obtain a fitted piecewise linear curve of discharge capacity over time.

[0230] The maximum capacity of the current state is obtained based on the fitted piecewise linear curve.

[0231] Optionally, the fourth determining unit 608 of the energy storage device state of charge determination device 600 provided in this application embodiment further includes:

[0232] The twelfth determining unit 624 is used to obtain a reference voltage lookup table corresponding to each of the multiple reference states of charge. The reference voltage lookup table indicates the reference voltage under the combination of multiple reference current multipliers and multiple reference temperatures.

[0233] The thirteenth determining unit 626 is used to determine, among multiple reference states of charge, the target state of charge that is closest to the state of charge of the energy storage device in the previous sampling period.

[0234] The fourteenth determining unit 628 is used to look up the target voltage corresponding to the combination of the current temperature and the current current ratio in the reference voltage lookup table corresponding to the target state of charge.

[0235] The fifteenth determining unit 630 is used to determine the state of charge of the energy storage device as the target state of charge when the current energy storage voltage reaches the target voltage.

[0236] Optionally, in the energy storage device state of charge determination device 600 provided in this application embodiment, the fourteenth determination unit 628 is specifically used for:

[0237] If the current temperature is between the first reference temperature and the second reference temperature among multiple reference temperatures, and the current current multiplier is between the first reference current multiplier and the second reference current multiplier among multiple reference current multipliers, then in the reference voltage lookup table, look up the first reference voltage corresponding to the combination of the first reference temperature and the first reference current multiplier, where the first reference temperature is less than the second reference temperature and the first reference current multiplier is less than the second reference current multiplier.

[0238] Based on the first reference temperature, the second reference temperature, the first reference voltage, the second reference voltage, and the current temperature, calculate the first voltage correction amount, where the second reference voltage is the reference voltage corresponding to the combination of the second reference temperature and the first reference current multiplier;

[0239] Based on the first reference temperature, the second reference temperature, the first reference current multiplier, the second reference current multiplier, the first reference voltage, the second reference voltage, the third reference voltage, and the fourth reference voltage, a second voltage correction amount is calculated, wherein the third reference voltage is the reference voltage corresponding to the combination of the first reference temperature and the second reference current multiplier, and the fourth reference voltage is the reference voltage corresponding to the combination of the second reference temperature and the second reference current multiplier.

[0240] like Figure 9 As shown, this application embodiment also provides an energy storage device 700, including a processor 710, a memory 720, and a program or instructions stored in the memory 720 and executable on the processor 710. When the program or instructions are executed by the processor 710, they implement the various processes of the above-described embodiment of the energy storage device state of charge determination method and can achieve the same technical effect. To avoid repetition, they will not be described again here.

[0241] The memory can be used to store software programs and various data. The memory may primarily include a first storage area for storing programs or instructions and a second storage area for storing data. The first storage area may store the operating system, application programs or instructions required for at least one function (such as sound playback, image playback, etc.). Furthermore, the memory 720 may include volatile memory or non-volatile memory, or both. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct memory bus RAM (DRRAM). The memory 720 in the embodiments of this application includes, but is not limited to, these and any other suitable types of memory.

[0242] In this application, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise expressly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can mean a fixed connection, a detachable connection, or an integral connection; "link" can mean a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0243] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0244] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to specific features, structures, materials, or characteristics described in connection with an embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0245] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the state of charge of an energy storage device, characterized in that, The method comprises: determining that the energy storage device enters a low-temperature working condition based on a storage voltage of the energy storage device; determining that the storage voltage experiences a trough to a peak with respect to time in a case that the energy storage device enters the low-temperature working condition; determining a state of charge of the energy storage device by using an ampere-hour integration method before the storage voltage experiences the peak with respect to time; determining the state of charge of the energy storage device by using dynamic compensation correction based on a current storage voltage, a current temperature and a current current rate of the energy storage device after the storage voltage experiences the peak with respect to time.

2. The energy storage device state of charge determination method of claim 1, wherein, The method of determining that the energy storage device enters the low-temperature working condition based on the storage voltage of the energy storage device comprises: detecting that the storage voltage is lower than a first voltage threshold, wherein the first voltage threshold is a voltage critical point at which the energy storage device enters the low-temperature working condition; acquiring a first time length during which the storage voltage remains lower than the first voltage threshold; determining that the energy storage device enters the low-temperature working condition if the first time length is greater than a first time length threshold.

3. The method of claim 1, wherein, The method of determining that the storage voltage experiences the trough to the peak with respect to time in the case that the energy storage device enters the low-temperature working condition comprises: determining that the storage voltage reaches a trough extreme voltage in the case that the energy storage device enters the low-temperature working condition; determining that a trough stage ends in response to the storage voltage after reaching the trough extreme voltage; determining that the storage voltage reaches a peak extreme voltage; determining that a peak stage ends in response to the storage voltage after reaching the peak extreme voltage.

4. The method of claim 3, wherein, The method of determining that the storage voltage reaches the trough extreme voltage comprises: setting a first reference value as a trough detection starting voltage, the trough detection starting voltage being greater than the trough extreme voltage; continuously comparing the storage voltage with the first reference value after the storage voltage is lower than the trough detection starting voltage, and updating the first reference value with the storage voltage if the storage voltage is lower than the first reference value; determining that the storage voltage reaches the trough extreme voltage if the first reference value remains unchanged for a second time length threshold, wherein the trough extreme voltage is the value of the first reference value remaining unchanged.

5. The method of claim 3, wherein, The method of determining that the trough stage ends in response to the storage voltage after reaching the trough extreme voltage comprises: calculating a trough end voltage based on the trough extreme voltage and a first voltage increment, wherein the first voltage increment is a voltage increment required for leaving the trough stage; periodically collecting the storage voltage, and recording a first cycle number of the storage voltage being greater than the trough end voltage continuously; determining that the trough stage ends if the first cycle number is greater than a first cycle number threshold.

6. The method of claim 3, wherein, The method of determining that the storage voltage reaches the peak extreme voltage comprises: setting a second reference value as a peak detection starting voltage, the peak detection starting voltage being lower than the peak extreme voltage; continuously comparing the storage voltage with the second reference value after the storage voltage is greater than the peak detection starting voltage, and updating the second reference value with the storage voltage if the storage voltage is greater than the second reference value; determining that the storage voltage reaches the peak extreme voltage if the second reference value remains unchanged for a third time length threshold, wherein the peak extreme voltage is the value of the second reference value remaining unchanged. If the second reference value remains unchanged for a third duration threshold, it is determined that the energy storage voltage reaches the peak extreme voltage, wherein the peak extreme voltage is the value at which the second reference value remains unchanged.

7. The method of claim 3, wherein, The step of determining the end of the peak phase after the storage voltage reaches the peak extreme voltage includes: Based on the peak extreme voltage and the first voltage reduction, the peak end voltage is calculated, wherein the first voltage reduction is the voltage reduction required to leave the peak stage. The stored voltage is periodically collected, and the number of second cycles in which the stored voltage is continuously greater than the peak end voltage is recorded; If the second cycle number is greater than the second cycle number threshold, the peak phase is determined to have ended.

8. The energy storage device state of charge determination method of claim 1 wherein, The determination of the state of charge of the energy storage device using the ampere-hour integration method includes: The current sampling current, sampling period interval, current maximum capacity of the energy storage device, and state of charge of the energy storage device in the previous sampling period are obtained from the sampling of the energy storage device in the current sampling period. Calculate the state of charge increment based on the current sampling current, the sampling period interval, and the current maximum capacity. Based on the state of charge of the previous sampling period and the state of charge increment, the state of charge of the energy storage device in the current sampling period is determined.

9. The method of claim 8, wherein, The current maximum capacity is obtained in the following way: The energy storage device is subjected to discharge capacity testing at predetermined test intervals; For every two adjacent test time points, a straight line is fitted to the curve of discharge capacity changing with time to obtain a fitted piecewise linear curve of discharge capacity over time. Based on the fitted piecewise linear curve, the maximum capacity of the current state is obtained.

10. The energy storage device state of charge determination method of claim 1 wherein, The determination of the state of charge of the energy storage device based on its current storage voltage, current temperature, and current current ratio, using dynamic compensation correction, includes: Obtain reference voltage lookup tables corresponding to multiple reference states of charge, wherein the reference voltage lookup tables indicate the reference voltage under a combination of multiple reference current ratios and multiple reference temperatures; Among the plurality of reference states of charge, the target state of charge that is closest to the state of charge of the energy storage device in the previous sampling period is determined. In the reference voltage lookup table corresponding to the target state of charge, find the target voltage corresponding to the combination of the current temperature and the current current ratio; If the current energy storage voltage reaches the target voltage, the state of charge of the energy storage device is determined as the target state of charge.

11. The method of claim 10, wherein, The step of searching for the target voltage corresponding to the combination of the current temperature and the current rate in the reference voltage lookup table corresponding to the target state of charge includes: if the current temperature is between a first reference temperature and a second reference temperature in the plurality of reference temperatures, and the current current ratio is between a first reference current ratio and a second reference current ratio in the plurality of reference current ratios, in the reference voltage lookup table, a first reference voltage corresponding to a combination of the first reference temperature and the first reference current ratio is looked up, wherein the first reference temperature is less than the second reference temperature, and the first reference current ratio is less than the second reference current ratio; based on the first reference temperature, the second reference temperature, the first reference voltage, a second reference voltage, and the current temperature, a first voltage correction amount is calculated, wherein the second reference voltage is a reference voltage corresponding to a combination of the second reference temperature and the first reference current ratio; based on the first reference temperature, the second reference temperature, the first reference current ratio, the second reference current ratio, the first reference voltage, the second reference voltage, a third reference voltage, and a fourth reference voltage, a second voltage correction amount is calculated, wherein the third reference voltage is a reference voltage corresponding to a combination of the first reference temperature and the second reference current ratio, and the fourth reference voltage is a reference voltage corresponding to a combination of the second reference temperature and the second reference current ratio.

12. An energy storage device state of charge determination apparatus characterized by comprising: comprising: a first determination unit configured to determine, based on a storage voltage of an energy storage device, that the energy storage device enters a low-temperature working condition; a second determination unit configured to, in a case where the energy storage device enters the low-temperature working condition, determine that a change of the storage voltage over time experiences a trough to a peak; a third determination unit configured to, before the change of the storage voltage over time experiences the peak, determine a state of charge of the energy storage device by using an ampere-hour integration method; a fourth determination unit configured to, after the change of the storage voltage over time experiences the peak, determine the state of charge of the energy storage device by using dynamic compensation correction based on a current storage voltage, a current temperature, and a current current ratio of the energy storage device.

13. An energy storage device, characterized by, comprising a processor and a memory, the memory storing programs or instructions executable on the processor, the programs or instructions being executed by the processor to implement steps of the method for determining the state of charge of the energy storage device according to any one of claims 1 to 11.

Images