Battery State of Charge Estimation Device and Method Based on Coulomb Counter

Abstract

This invention relates to a battery state-of-charge (SOC) estimation apparatus and method, which can reduce SOC estimation errors caused by the accumulation of errors in current detection in coulomb counter-based battery SOC estimation, and improve the accuracy of SOC estimation by compensating for characteristics caused by battery temperature and aging. One aspect of the invention provides a battery SOC estimation apparatus, comprising: a first coulomb counter (STCC) that accumulates the battery current (Im) in each predetermined period to calculate a first charge change (ΔQ) for each period; a compensator that compensates for the first charge change (ΔQ) to calculate a second charge change (ΔQ_comp); a second coulomb counter (CCE) that accumulates the second charge change (ΔQ_comp) to calculate a first predicted charge (Qe); and a SOC estimator that estimates the battery's SOC based on the first predicted charge (Qe).

Description

Technical Field

[0001] This invention relates to a battery state-of-charge (SOC) estimation apparatus and method based on a coulomb counter. Specifically, the invention relates to a battery SOC estimation apparatus and method that can reduce SOC estimation errors caused by the accumulation of current detection errors in coulomb counter-based battery SOC estimation, and improve the accuracy of SOC estimation by compensating for characteristics caused by battery temperature and aging. Background Technology

[0002] Coulomb counter-based techniques are widely used to estimate the state of charge (SOC) of batteries. This technique detects the battery current and accumulates the detected currents to estimate the battery's charge, and then uses this estimated charge to determine the SOC. Also known as the current accumulation method, this coulomb counter-based SOC estimation technique is widely used due to its advantage of providing a relatively accurate and simple method for SOC estimation.

[0003] However, conventional battery state-of-charge estimation techniques based on coulomb counters predict the remaining charge of a battery by continuously summing the measured currents. Even if there are some errors in the process of measuring the current, these errors will accumulate and may lead to larger errors in the prediction of the remaining charge of the battery over time.

[0004] Furthermore, conventional coulomb counter-based battery state-of-charge (SOC) estimation techniques do not reflect changes in battery characteristics due to temperature and aging, thus leaving room for improvement. For example, if a battery is at low temperatures or aging, its full-charge capacity (or usable capacity) may be significantly reduced compared to its design capacity. When this reduction in full-charge capacity is not reflected, the accuracy of the SOC estimation will decrease. Summary of the Invention

[0005] Technical issues

[0006] According to embodiments, the present invention aims to improve the problem of decreased accuracy of state of charge estimation in battery state of charge estimation due to the accumulation of errors such as current measurement in coulomb counter-based estimation.

[0007] According to embodiments, the present invention aims to improve the accuracy of state of charge estimation by reflecting changes in battery characteristics due to battery temperature and aging in the battery state of charge estimation based on a coulomb counter.

[0008] According to embodiments, the present invention aims to estimate the state of charge of a battery based on the changes in full charge capacity due to battery temperature and aging in a coulomb counter-based battery state of charge estimation.

[0009] According to embodiments, the present invention aims to simplify the structure and reduce the power consumption used for state of charge estimation in battery state-of-charge estimation based on coulomb counters.

[0010] Technical solution

[0011] One aspect of the present invention provides a battery state of charge estimation apparatus, comprising: a first coulomb counter STCC, which accumulates the battery current Im in each predetermined period to calculate a first charge change ΔQ corresponding to each period; a compensator, which compensates for the first charge change ΔQ to calculate a second charge change ΔQ_comp; a second coulomb counter CCE, which accumulates the second charge change ΔQ_comp to calculate a first predicted charge Qe; and a state of charge estimator, which estimates the state of charge of the battery based on the first predicted charge Qe.

[0012] In the battery state of charge estimation device, the compensator uses the first predicted charge amount Qe to calculate the predicted open circuit voltage OCVe, and uses the predicted open circuit voltage OCVe to calculate the second charge change ΔQ_comp.

[0013] In the battery state of charge estimation device, when calculating the predicted open circuit voltage OCVe using the first predicted charge Qe, a first lookup table LUT1 containing data on the relationship between the open circuit voltage OCV and the charge Q corresponding to the battery is used.

[0014] In the battery state of charge estimation device, when the magnitude of the battery current Im is less than a first threshold, the compensator compensates for the first charge change ΔQ in order to reduce the difference between the predicted open circuit voltage OCVe and the battery terminal voltage Vm, thereby calculating the second charge change ΔQ_comp.

[0015] In the battery state of charge estimation device, the second charge change ΔQ_comp is calculated based on the value obtained by subtracting the predicted open circuit voltage OCVe from the battery terminal voltage Vm and multiplying it by a first constant C1.

[0016] In the battery state of charge estimation device, the first constant C1 is predetermined based on the internal resistance value of the battery.

[0017] In the battery state of charge estimation device, when the magnitude of the battery current Im is greater than the second threshold, the compensator compensates for the first charge change ΔQ to reduce the difference between the first overpotential prediction value Vds_e and the first overpotential reference value Vds_ref, thereby calculating the second charge change ΔQ_comp.

[0018] In the battery state of charge estimation device, the first overpotential prediction value Vds_e is calculated based on the value obtained by subtracting the predicted open circuit voltage OCVe from the battery terminal voltage Vm, and the first overpotential reference value Vds_ref is calculated using a second lookup table containing information on the internal resistance R of the battery and the second overpotential Vov.

[0019] In the battery state of charge estimation device, the information corresponding to the internal resistance R and the second overpotential Vov of the battery, contained in the second lookup table LUT2, is data obtained by applying intermittent constant current pulses to a battery in an unaged state at room temperature.

[0020] In the battery state of charge estimation device, the compensator calculates a charge change compensation coefficient comp_rate, and multiplies the charge change compensation coefficient comp_rate by the first charge change ΔQ to calculate the second charge change ΔQ_comp.

[0021] In the battery state of charge estimation device, when the first overpotential prediction value Vds_e is less than the first overpotential reference value Vds_ref, the charge change compensation coefficient comp_rate is set to 1.

[0022] In the battery state of charge estimation device, when the first overpotential prediction value Vds_e is greater than the first overpotential reference value Vds_ref, the charge change compensation coefficient comp_rate also increases as the first overpotential ratio Vds_rate increases.

[0023] In the battery state of charge estimation device, the first overpotential ratio Vds_rate is proportional to the value obtained by dividing the first overpotential prediction value Vds_e by the first overpotential reference value Vds_ref.

[0024] In the battery state of charge estimation device, when the first overpotential prediction value Vds_e is greater than the first overpotential reference value Vds_ref, the charge change compensation coefficient comp_rate also increases as the charge change rate Qm_rate increases.

[0025] In the battery state of charge estimation device, the compensator further includes a third coulomb counter that accumulates the first charge change ΔQ to calculate the second predicted charge Qm, wherein the charge change rate Qm_rate is determined based on the change rate of the second predicted charge Qm.

[0026] Another aspect of the present invention provides a battery state of charge estimation method, executed by a battery state of charge estimation device, the method comprising: accumulating battery current Im to calculate a first charge change ΔQ; compensating the first charge change ΔQ to calculate a second charge change ΔQ_comp; accumulating the second charge change ΔQ_comp to calculate a first predicted charge Qe; and estimating the battery state of charge based on the first predicted charge Qe.

[0027] In the battery state of charge estimation method, in the step of calculating the second charge change ΔQ_comp by compensating for the first charge change ΔQ, the predicted open circuit voltage OCVe is calculated using the first predicted charge Qe, and the first charge change ΔQ is compensated using the predicted open circuit voltage OCVe, thereby calculating the second charge change ΔQ_comp.

[0028] In the battery state of charge estimation method, in the step of calculating the second charge change ΔQ_comp by compensating for the first charge change ΔQ, when the magnitude of the battery current Im is less than the first threshold TH1, the first charge change ΔQ is compensated to reduce the difference between the predicted open circuit voltage OCVe and the battery terminal voltage Vm, thereby calculating the second charge change ΔQ_comp.

[0029] In the battery state of charge estimation method, the second charge change ΔQ_comp is calculated based on the value obtained by subtracting the predicted open circuit voltage OCVe from the battery terminal voltage Vm and multiplying it by a first constant C1.

[0030] In the battery state of charge estimation method, in the step of calculating the second charge change ΔQ_comp by compensating for the first charge change ΔQ, when the magnitude of the battery current Im is greater than the second threshold, the first charge change ΔQ is compensated to reduce the difference between the first overpotential prediction value Vds_e and the first overpotential reference value Vds_ref, thereby calculating the second charge change ΔQ_comp.

[0031] Technical effect

[0032] According to the present invention, and according to embodiments, the problem of decreased accuracy of state-of-charge estimation due to the accumulation of errors such as current measurement in battery state-of-charge estimation based on coulomb counters can be improved.

[0033] According to the present invention, and according to embodiments, the accuracy of state of charge estimation can be improved by reflecting changes in battery characteristics due to battery temperature and aging in the coulomb counter-based battery state of charge estimation.

[0034] According to the present invention, and according to an embodiment, the state of charge of a battery can be estimated based on the full charge capacity, which varies due to battery temperature and aging, in a coulomb counter-based battery state of charge estimation.

[0035] According to one embodiment of the present invention, the structure can be simplified and the power consumption used for state of charge estimation can be reduced in battery state of charge estimation based on a coulomb counter. Attached Figure Description

[0036] Figure 1 A battery state-of-charge estimation device according to an embodiment of the present invention is shown.

[0037] Figure 2 A battery state of charge estimation device according to another embodiment of the present invention is shown.

[0038] Figure 3 A battery state of charge estimation device according to yet another embodiment of the present invention is shown.

[0039] Figure 4 A battery state of charge estimation device according to yet another embodiment of the present invention is shown.

[0040] Figure 5 A battery state-of-charge estimation method according to an embodiment of the present invention is shown.

[0041] Figure 6 A battery state-of-charge estimation method according to another embodiment of the present invention is shown.

[0042] Figure 7 A battery state of charge estimation method according to yet another embodiment of the present invention is shown. Detailed Implementation

[0043] In the following, some embodiments of the present invention will be described in detail with reference to the exemplary accompanying drawings. It should be noted that when affixing reference numerals to the constituent elements of the various drawings, the same reference numerals are assigned to the same constituent elements as much as possible, even if they are shown in different drawings. Furthermore, in describing the present invention, detailed descriptions of related known structures or functions are omitted if it is determined that a specific description of such structures or functions might obscure the main points of the invention.

[0044] Furthermore, when describing the constituent elements of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the constituent element from other constituent elements, and do not limit the nature, order, or sequence of the constituent elements. When it is stated that a constituent element is "connected," "coupled," or "joined" with other constituent elements, the constituent element may be directly connected or joined to the other constituent elements, but it can also be understood that another constituent element may be "connected," "coupled," or "joined" between the constituent elements.

[0045] Figure 1 A battery state of charge estimation device 100 according to an embodiment of the present invention is shown.

[0046] refer to Figure 1 The battery state of charge estimation device 100 may include a first coulomb counter (STCC) 110, a compensator 120, a second coulomb counter (CCE) 130, and a state of charge estimator (SOC Estimator) 140.

[0047] The battery state-of-charge estimation device 100 can be used to estimate the state of charge of a battery in various devices that use batteries. For example, the battery state-of-charge estimation device 100 may be highly applicable in portable electronic devices such as mobile phones, tablet computers, and laptop computers, but its use is not limited to these. The battery state-of-charge estimation device 100 can be implemented in various ways, for example, as a separate device in various devices that use batteries, or as a functional element within another device (e.g., a controller) that is already installed in that device.

[0048] The first coulomb counter 110 can calculate the first charge change ΔQ corresponding to each cycle by accumulating the battery current Im in each specified cycle.

[0049] The battery current Im can be a value obtained by detecting the current used to charge or discharge the battery. A conventional current sensing unit can be used to detect the battery current Im. For example, a current sensing resistor or a current transformer can be used, but it is not limited to these. The battery current Im sensing unit can be included in the battery state-of-charge estimation device 100, but the battery state-of-charge estimation device 100 can also obtain battery current Im information from an external battery current Im sensing unit.

[0050] The first coulomb counter 110 can perform a cycle-by-cycle accumulation function for the battery current Im. That is, the first coulomb counter 110 can operate as follows: after calculating the first charge change ΔQ by accumulating the battery current Im in each predetermined cycle, it is initialized (resct), and then the process of accumulating the battery current Im is repeated for the predetermined cycle. For example, the first coulomb counter 110 can calculate the first charge change ΔQ by summing the digitized sampled data of the battery current Im a predetermined number of times. In this case, the value obtained by multiplying the sampling period of the battery current Im by the number of accumulated data points can be understood as the accumulation period of the first coulomb counter 110.

[0051] The reason for performing the cycle-by-cycle accumulation function on the first coulomb counter 110 will be explained. As will be explained in detail later, in this embodiment, after calculating the second charge change ΔQ_comp by compensating the first charge change ΔQ with the compensator 120, the second charge change ΔQ_comp is accumulated in the second coulomb counter 130 to calculate the first predicted charge Qe. When the first coulomb counter 110 is not used, the compensator 120 needs to perform compensation work for each sampled battery current Im. In this case, when noise is included in each sampled battery current Im, the operation of the compensator 120 may not be smooth, and the power consumption may increase as the number of times the compensator 120 operates increases. In this embodiment, by using the first coulomb counter 110 to accumulate the battery current Im in each predetermined cycle to generate the first charge change ΔQ corresponding to each cycle, the compensator 120 can perform compensation work for the first charge change ΔQ corresponding to each cycle. In this case, since the first charge change ΔQ is the integral of most of the sampled battery current Im values, the influence of noise is reduced, and the operating frequency of the compensator 120 is reduced, thus having the advantage of reduced power consumption.

[0052] At this point, it is preferable to set the accumulation period of the first coulomb counter 110 to a level where the changes in battery states such as battery current Im, battery voltage Vm, and state of charge (SOC) are not significant. This is because if the accumulation period of the first coulomb counter 110 is set too long, resulting in significant changes in battery states, it will be difficult for the compensator 120 to perform appropriate compensation for the first charge change ΔQ due to these changes. For example, when the battery current Im is sampled via an ADC (analog-digital converter) at a period of approximately 0.3 seconds, and the first coulomb counter 110 accumulates 4 to 8 samples of the battery current Im, the accuracy of the state of charge estimation can be improved by appropriately compensating for the first charge change ΔQ while reducing noise and power consumption.

[0053] Compensator 120 can calculate a second charge change ΔQ_comp by compensating for a first charge change ΔQ. According to an embodiment, compensator 120 can use battery current Im, battery terminal voltage Vm, and a first predicted charge Qe to compensate for the first charge change ΔQ, thereby calculating the second charge change ΔQ_comp. According to an embodiment, compensator 120 uses the first predicted charge Qe to calculate the predicted open-circuit voltage OCVe, and uses the predicted open-circuit voltage OCVe to compensate for the first charge change ΔQ, thereby calculating the second charge change ΔQ_comp. Compensator 120 will be described in more detail below.

[0054] The second coulomb counter 130 (CCE) calculates the first predicted charge Qe by accumulating the second charge change ΔQ_comp. If the first coulomb counter 110 performs a periodic accumulation function, the second coulomb counter 130 can be understood as accumulating and summing the battery current Im without a specific period. The difference from the general current accumulation method is that the second coulomb counter 130 does not directly accumulate the battery current Im, but instead accumulates the second charge change ΔQ_comp as a value compensated by the compensator 120.

[0055] The state of charge estimator 140 (SOC Estimator) can estimate the battery's state of charge based on a first predicted charge quantity Qe. According to embodiments, the battery state of charge output by the SOC estimator 140 can be SOC (state of charge), but is not limited to this. For example, the battery state of charge can be a value corresponding to a value obtained by dividing the first predicted charge quantity Qe by the battery's design capacity.

[0056] Figure 2 A battery state of charge estimation device 200 according to another embodiment of the present invention is shown.

[0057] refer to Figure 2 The battery state of charge estimation device 200 may include a first coulomb counter 110, a compensator 220, a second coulomb counter 130, and a state of charge estimator 140. The first coulomb counter 110, the second coulomb counter 130, and the state of charge estimator 140 may be referenced without departing from the following description. Figure 1 Perform similar work in the manner described.

[0058] The compensator 220 may include a first compensator 221, a second compensator 222, a multiplier 223, and a multiplexer 224.

[0059] The first compensator 221 can operate in a manner that eliminates the accumulated error of the first predicted charge Qe when the battery is in a relaxed state.

[0060] Therefore, according to an embodiment, when the battery current Im is less than a first threshold, the first compensator 221 can calculate a second charge change ΔQ_comp to compensate for the first charge change ΔQ by reducing the difference between the predicted open circuit voltage OCVe and the battery terminal voltage Vm. According to an embodiment, the battery current Im can be the average of the absolute values ​​of the battery current Im during the accumulation period of the first coulomb counter 110, but is not limited thereto. Furthermore, according to an embodiment, the first compensator 221 can be configured to operate only when the determination that the battery current Im is less than the first threshold is sustained for more than a predetermined number of times. The first threshold can be set to a value that indicates the battery is in a certain degree of relaxation.

[0061] When the battery is in a fully relaxed state, the battery terminal voltage Vm can be substantially the same as the actual open-circuit voltage OCV of the battery. In this embodiment, since an equivalent model of the battery is not used, an attempt is not made to accurately estimate the actual open-circuit voltage OCV of the battery. The predicted open-circuit voltage OCVe in this embodiment is a value simply calculated from the first predicted charge Qe using a lookup table, as described later, based on the premise that there is some degree of difference between the predicted open-circuit voltage OCVe and the actual open-circuit voltage OCV. In this embodiment, under this understanding, when the battery current Im is less than a first threshold, the battery terminal voltage Vm will be more similar to the actual open-circuit voltage OCV than the predicted open-circuit voltage OCVe. Under this assumption, the second charge change ΔQ_comp is calculated to compensate for the first charge change ΔQ by having the predicted open-circuit voltage OCVe follow the battery terminal voltage Vm, thereby eliminating the accumulated error of the first predicted charge Qe.

[0062] If the battery current Im is less than the first threshold for a prolonged period (e.g., several hours), the battery is in a fully relaxed state. Only in this state can the battery terminal voltage Vm be the same as the actual open circuit voltage OCV. However, in this embodiment, as long as the battery current Im is less than the first threshold, even if sufficient time has not elapsed, it is assumed that the battery terminal voltage Vm is similar to the actual open circuit voltage OCV. The system can operate in a way that the predicted open circuit voltage OCVe follows the battery terminal voltage Vm.

[0063] According to this embodiment, the accumulation error of the first predicted charge Qe during battery operation (even if the battery is not sufficiently relaxed) can be reduced. If the battery is in a sufficiently relaxed state, the error of the first predicted charge Qe can be almost completely eliminated automatically by the same algorithm. As described above, according to this embodiment, without using a complex system that accurately estimates the actual open circuit voltage OCV through a battery equivalent model, the accumulation of the error of the first predicted charge Qe can be prevented by a simple method, thereby improving the accuracy of battery state-of-charge estimation.

[0064] According to an embodiment, as shown in the following mathematical formula 1, the second charge change ΔQ_comp can be calculated by multiplying the value obtained by subtracting the predicted open circuit voltage OCVe from the battery terminal voltage Vm by the first constant C1.

[0065]

Mathematical Formula 1

[0066] ΔQ_comp=(Vm-OCVe)·C1

[0067] Here, the first constant C1 is a constant that affects the speed at which the predicted open circuit voltage OCVe follows the battery terminal voltage Vm, and can be determined based on the battery's internal resistance value.

[0068] Mathematical formula 1 illustrates the case where the second charge change ΔQ_comp is independent of the first charge change ΔQ. However, it can be set differently, where the second charge change ΔQ_comp is affected by the first charge change ΔQ, while the predicted open circuit voltage OCVe follows the battery terminal voltage Vm.

[0069] As described above, when the first compensator 221 is in a state where the battery current Im is less than the first threshold (even if the battery is not in a sufficiently relaxed state), the error of the first predicted charge Qe can be prevented from accumulating by making the predicted open circuit voltage OCVe follow the battery terminal voltage Vm.

[0070] The second compensator 222 can estimate the state of charge by using the first overpotential Vds to reflect the different full-charge capacity caused by battery temperature and aging, etc., when charging and discharging current flows through the battery.

[0071] First, let's explain overpotential. If current flows through an electrode in equilibrium, the electrode potential will deviate from the equilibrium potential; the degree of this deviation is called overpotential. Overpotential can be understood as the combined effect of the influence caused by the battery's internal resistance and other influences (such as the slow electrochemical reaction of the electrolyte, diffusion rate, and uneven current distribution). In this specification, the overall overpotential caused by the combined effect of the battery's internal resistance and other influences is referred to as the first overpotential Vds, and the overpotential caused by influences other than the battery's internal resistance is referred to as the second overpotential Vov. That is, as shown in Equation 2, the first overpotential Vds can be understood as the sum of the voltage caused by the internal resistance and the second overpotential Vov.

[0072]

Mathematical Formula 2

[0073] Vds=Im·R+Vov

[0074] The first overpotential Vds, as shown in Equation 2, can be calculated using the battery's internal resistance and the second overpotential Vov. However, depending on the situation, it can also be calculated using the difference between the battery terminal voltage Vm and the battery's open circuit voltage OCV, as shown in Equation 3.

[0075]

Mathematical Expression 3

[0076] Vds=Vm-OCV

[0077] According to the embodiment, when the battery current Im is greater than the second threshold, the second compensator 222 can compensate for the first charge change ΔQ to calculate the second charge change ΔQ_comp in order to reduce the difference between the first overpotential prediction value Vds_e and the first overpotential reference value Vds_ref.

[0078] The magnitude of the battery current Im can be the average of the absolute values ​​of the battery current Im during the accumulation period of the first coulomb counter 110, but is not limited to this. Furthermore, according to an embodiment, the second compensator 222 can be configured to operate only after a predetermined number of determinations that the magnitude of the battery current Im is greater than a second threshold. The second threshold can be set to a value that determines whether the battery is in a charging or discharging state.

[0079] The first overpotential reference value Vds_ref is a reference value corresponding to the first overpotential, and can be a value pre-measured at room temperature for a corresponding reference battery (e.g., a new battery or a battery in an unaged state). According to an embodiment, the first overpotential reference value Vds_ref can be calculated using the internal resistance and the second overpotential Vov pre-measured at room temperature for the corresponding reference battery. Mathematical formula 2 can be used when calculating the first overpotential reference value Vds_ref using the internal resistance and the second overpotential Vov.

[0080] The first overpotential prediction value Vds_e is a value calculated during the operation of the battery state of charge estimation device 200, and according to an embodiment, as shown in Formula 4, it can be calculated based on the battery terminal voltage Vm minus the predicted open circuit voltage OCVe.

[0081]

Mathematical Expression 4

[0082] Vds_e=Vm-OCVe

[0083] That is, the first overpotential prediction value Vds_e is a value calculated using the detected battery terminal voltage Vm and the predicted open circuit voltage OCVe, which can be understood as the first overpotential currently predicted by the battery charging state estimation device 200.

[0084] When the first overpotential prediction value Vds_e is greater than the first overpotential reference value Vds_ref, the current battery may have a reduced full-charge capacity compared to the design capacity due to low temperature or aging. In this case, the second compensator 222 compensates for the first charge change ΔQ in the direction of the first overpotential prediction value Vds_e, following the first overpotential reference value Vds_ref, to calculate the second charge change ΔQ_comp, thereby estimating the state of charge in a way that reflects the change in full-charge capacity.

[0085] When temperatures are low or the battery ages, the first overpotential Vds increases compared to a battery under baseline conditions, while the battery's full-charge capacity (usable capacity) decreases. When the state of charge (SOC) is calculated without reflecting the reduction in full-charge capacity due to battery temperature or aging, the accuracy of the calculated SOC may be reduced. For example, if the battery's full-charge capacity decreases to 50% of its design capacity due to low temperatures, even if the battery is charged to 100% of its full-charge capacity, the SOC calculated based on the design capacity may be calculated as 50%. As mentioned above, calculating the SOC based on the design capacity without considering changes in full-charge capacity due to temperature or aging and providing the results to the user can be confusing.

[0086] In this embodiment, to prevent such problems, the state of charge (SOC) can be calculated to reflect changes in full-charge capacity due to temperature or aging. For example, when the full-charge capacity decreases due to low battery temperature or aging, the charge change compensation factor comp_rate is increased to make the second charge change ΔQ_comp greater than the first charge change ΔQ, thereby allowing the first predicted charge Qe, which is the output of the second coulomb counter 130, to have a larger value. In this case, the SOC, obtained by dividing the first predicted charge Qe by the design capacity, has a slightly larger value, thus effectively reflecting the reduction in full-charge capacity. That is, in the prior art, when the full-charge capacity decreases due to temperature or aging, the estimated SOC may not be close to 0% or 100%, while this embodiment solves this problem.

[0087] According to an embodiment, as the first overpotential ratio Vds_rate, which is the ratio of the first overpotential prediction value Vds_e to the first overpotential reference value Vds_ref, increases, the charge change compensation coefficient comp_rate can be increased. An increase in the first overpotential ratio Vds_rate means that the first overpotential prediction value Vds_e increases compared to the first overpotential reference value Vds_ref, which can be understood as a deepening reduction in full-charge capacity due to temperature or aging. In this case, by increasing the charge change compensation coefficient comp_rate, the degree of increase in the first predicted charge Qe is amplified, thereby more effectively reflecting changes in full-charge capacity.

[0088] The multiplier 223 can calculate the third charge change ΔQ_cr by multiplying the charge change compensation coefficient comp_rate, which is the output of the second compensator 222, by the first charge change ΔQ.

[0089] Multiplexer 224 can output a value selected from the fourth charge change ΔQ_track (output of first compensator 221) and the third charge change ΔQ_cr (generated by second compensator 222) according to a mode. For this purpose, multiplexer 224 can receive a mode selection signal mode from a controller (not shown) and output the value selected from the third charge change ΔQ_cr and the fourth charge change ΔQ_track according to mode selection signal mode as a second charge change ΔQ_comp. For example, as shown in Equation 5, when mode selection signal mode is '0', multiplexer 224 can output the third charge change ΔQ_cr, and when mode selection signal mode is '1', multiplexer 224 can output the fourth charge change ΔQ_track. That is, multiplexer 224 can make first compensator 221 and second compensator 222 operate selectively according to mode selection signal mode.

[0090]

Mathematical Expression 5

[0091]

[0092] on the other hand, Figure 2 An example is shown where the first compensator 221 and the second compensator 222 are used together, but the battery state of charge estimation device 200 can selectively use either the first compensator 221 or the second compensator 222. In this case, the multiplexer 224 can be omitted or used to select whether the corresponding controller is operational.

[0093] Furthermore, the first threshold for determining whether the first compensator 221 is operational and the second threshold for determining whether the second compensator 222 is operational can be the same value. In this case, the first compensator 221 can operate when the battery current Im is less than the first threshold (or the second threshold), and the second compensator 222 can operate when the battery current Im is greater than the first threshold (or the second threshold). Alternatively, according to an embodiment, the second threshold can have a value greater than the first threshold. In this case, the first compensator 221 can operate when the battery current Im is less than the first threshold, neither the first compensator 221 nor the second compensator 222 operates when the battery current Im is greater than the first threshold and less than the second threshold, and the second compensator 222 can operate when the battery current Im is greater than the second threshold.

[0094] Figure 3 A battery state of charge estimation device 300 according to another embodiment of the present invention is shown.

[0095] refer to Figure 3 The battery state-of-charge estimation device 300 may include a first coulomb counter 110, a compensator 320, a second coulomb counter 130, and a state-of-charge estimator 140. The compensator 320 may include a first compensator 321, a second compensator 322, a multiplier 323, a multiplexer 324, a first lookup table (LUT1) 325, a second lookup table (LUT2) 326, and a third coulomb counter (CCM) 327. The first coulomb counter 110, the second coulomb counter 130, and the state-of-charge estimator 140 may be referenced without departing from the following description. Figure 1 and Figure 2 It works in a similar manner. Furthermore, the first compensator 321, the second compensator 322, the multiplier 323, and the multiplexer 324 included in the compensator 320 may be referenced without departing from the following description. Figure 2 The explanation works in a similar way.

[0096] The first lookup table (LUT1) 325 may include data relating the open-circuit voltage OCV and charge Q of the corresponding battery. The compensator 320 may use the first lookup table 325 and calculate the predicted open-circuit voltage OCVe based on the first predicted charge Qe. The predicted open-circuit voltage OCVe calculated using the first lookup table 325 can be applied to the first compensator 321 and the second compensator 322 as described above.

[0097] The second lookup table 326 (LUT2) may include data on the internal resistance R and the second overpotential Vov of the corresponding battery based on the open circuit voltage OCV and the battery current Im. The compensator 320 may utilize the second lookup table 326 and extract information on the internal resistance R and the second overpotential Vov of the corresponding reference battery based on the predicted open circuit voltage OCVe and the battery current Im, thereby calculating a first overpotential reference value Vds_ref. According to an embodiment, the first overpotential reference value Vds_ref can be calculated by adding the value obtained by multiplying the battery current Im by the battery's internal resistance R to the second overpotential Vov. As described above, the compensator 320 uses the second lookup table 326, which includes information on the internal resistance R and the second overpotential Vov of the corresponding battery, to calculate the first overpotential reference value Vds_ref.

[0098] The data for the internal resistance R and the second overpotential Vov of the corresponding battery, contained in the second lookup table 326, can be obtained through an experiment of applying intermittent constant current pulses to a battery (reference battery) in an unaged state at room temperature. In this case, it has the advantage of being able to obtain the data for the internal resistance R and the second overpotential Vov of the corresponding battery through simple experiments.

[0099] The data for the internal resistance R and / or the second overpotential Vov of the corresponding battery may vary depending on the magnitude of the battery current Im. It is difficult to store all the data for the internal resistance R and / or the second overpotential Vov of the corresponding battery according to the magnitude of various battery current Im in the second lookup table 326. Therefore, the data for the corresponding specified battery current Im can be stored in the second lookup table 326 and then the curve fitting function can be used to calculate the data for the internal resistance R and / or the second overpotential Vov of the corresponding battery.

[0100] The third coulomb counter (CCM) 327 can accumulate the first charge change ΔQ to calculate the second predicted charge Qm. Unlike the second coulomb counter 130, the third coulomb counter 327 can directly accumulate the first charge change ΔQ in the uncompensated state.

[0101] As mentioned as a problem with the prior art, the second predicted charge quantity Qm, which is the output of the third coulomb counter 327, may contain accumulated errors. However, as will be explained later, in the second compensator 322, instead of using the second predicted charge quantity Qm to estimate the state of charge, it is applied to calculate the charge change rate Qm_rate to calculate the charge change compensation coefficient comp_rate. Therefore, the accumulated error contained in the second predicted charge quantity Qm does not pose a problem. On the other hand, the first predicted charge quantity Qe, which is the output of the second coulomb counter 130, is accumulated with the second charge change ΔQ_comp, and therefore may change drastically due to the operation of the first compensator 321 or the second compensator 322. In contrast, the second predicted charge quantity Qm is directly accumulated with the first charge change ΔQ in the uncompensated state, and therefore the drastic changes are smaller. Therefore, the second predicted charge quantity Qm may be more suitable than the first predicted charge quantity Qe for extracting the charge change rate Qm_rate.

[0102] As described above, the first compensator 321 can calculate the fourth charge change ΔQ_track based on the predicted open circuit voltage OCVe and the battery voltage Vm. The first compensator 321 can operate when the battery current Im is less than a first threshold.

[0103] According to an embodiment, the first compensator 321 can calculate the value of the fourth charge change amount ΔQ_track based on the different magnitudes of the battery voltage Vm and the predicted open circuit voltage OCVe. For example, when the battery voltage Vm is greater than the predicted open circuit voltage OCVe, as shown in Equation 6, the fourth charge change amount ΔQ_track is set to '0' so that the predicted open circuit voltage OCVe does not change. When the battery voltage Vm is less than the predicted open circuit voltage OCVe, the fourth charge change amount ΔQ_track is calculated as shown in Equation 7 so that the predicted open circuit voltage OCVe follows the battery voltage Vm.

[0104]

Mathematical Expression 6

[0105]

[0106] In Equation 6, when the battery voltage Vm is greater than the predicted open circuit voltage OCVe, the reason for setting the fourth charge change ΔQ_track to '0' is to prevent the following problem: when the fourth charge change ΔQ_track is given a positive value to increase the predicted open circuit voltage OCVe, the battery will increase the first predicted charge Qe and the calculated state of charge while maintaining the discharge state.

[0107] Furthermore, in Equation 6, the first constant C1 is a constant that affects the speed at which the predicted open-circuit voltage OCVe follows the battery terminal voltage Vm. By appropriately setting the first constant C1, the predicted open-circuit voltage OCVe can progressively follow the battery terminal voltage Vm. According to an embodiment, the first constant C1 is set based on the internal resistance R of the battery, such that the predicted open-circuit voltage OCVe follows the battery terminal voltage Vm at a rate matching the battery's time constant.

[0108] As described above, in the second compensator 322, when the battery current Im is greater than the second threshold, the second charge change ΔQ_comp is calculated to compensate for the first charge change ΔQ in order to reduce the difference between the first overpotential prediction value Vds_e and the first overpotential reference value Vds_ref. For this purpose, the second compensator 322 can selectively use the predicted open circuit voltage OCVe obtained using the first lookup table 325, the internal resistance R and the second overpotential Vov obtained using the second lookup table 326, the second predicted charge Qm obtained using the third coulomb counter 327, and the battery voltage Vm and current Im to calculate the charge change compensation coefficient comp_rate. The charge change compensation coefficient comp_rate calculated by the second compensator 322 can be used to calculate the second charge change ΔQ_comp by multiplying it by the first charge change ΔQ.

[0109] According to the embodiment, when the first overpotential prediction value Vds_e is less than the first overpotential reference value Vds_ref, the second compensator 322 can set the charge change compensation coefficient comp_rate to 1. When the first overpotential prediction value Vds_e is less than the first overpotential reference value Vds_ref, it indicates that the full-charge capacity is greater than the design capacity, which may occur under conditions such as high temperature, but generally the difference is small and can be ignored. Furthermore, even if slight aging occurs, the resulting decrease in full-charge capacity will offset the increase in full-charge capacity caused by high temperature. Therefore, compensation for the case where the first overpotential prediction value Vds_e is less than the first overpotential reference value Vds_ref can be omitted. This method simplifies the compensation algorithm and reduces the power consumption of the compensator.

[0110] According to an embodiment, when the first overpotential prediction value Vds_e is greater than the first overpotential reference value Vds_ref, the second compensator 322 can be configured to increase the charge change compensation coefficient comp_rate as the first overpotential ratio Vds_rate increases. Here, the first overpotential ratio Vds_rate can be proportional to the absolute value obtained by dividing the first overpotential prediction value Vds_e by the first overpotential reference value Vds_ref (refer to mathematical formula 9). According to this method, as the first overpotential prediction value Vds_e increases (i.e., the reduction in full charge capacity increases), the charge change compensation coefficient comp_rate increases, allowing the compensator 320 to reflect the change in full charge capacity more accurately, thereby improving the accuracy of the state of charge estimation.

[0111] According to an embodiment, in the second compensator 322, when the first overpotential prediction value Vds_e is greater than the first overpotential reference value Vds_ref, the charge change compensation coefficient comp_rate can be increased as the charge change rate Qm_rate increases. Here, the charge change rate Qm_rate can be determined based on the change rate of the second predicted charge amount Qm. According to this method, the charge change compensation coefficient comp_rate increases as the recent charge change increases, thus reflecting the change in full charge capacity more comprehensively, thereby improving the accuracy of the state of charge estimation.

[0112] According to the embodiment, when the battery current Im is greater than the second threshold, the second compensator 322 can calculate the charge change compensation coefficient comp_rate by the following mathematical formulas 7 to 12. However, mathematical formulas 7 to 12 are only examples and this embodiment is not limited thereto.

[0113]

Mathematical Expression 7

[0114] Vds_ref(n)=R(n)·Im(n)+Vov(n)

[0115]

Mathematical Expression 8

[0116] Vds_e(n)=Vm(n)-OCVe(n)

Mathematical Expression 9

[0117]

[0118]

Mathematical Formula 10

[0119]

[0120]

Mathematical Expression 11

[0121]

[0122]

Mathematical Expression 12

[0123] comp_rate(n)=Qm_rate(n)·{1+SF(n)·Vds_rate(n)}

[0124] The constants C2, C3, C4, etc., used in mathematical formulas 10 to 12 can be set appropriately according to the situation. In mathematical formula 10, Qm(nT) is the second predicted charge Qm T units in advance from now. For example, when T = 10, the charge change rate Qm_rate can be calculated by using the degree of change between the second predicted charge Qm(n-10) ten units in advance from now and the current second predicted charge Qm(n). In mathematical formula 11, Q_max is the maximum charge, and SF (smoothing factor) can be understood as the value used to make the charge change compensation coefficient comp_rate change smoothly.

[0125] As described above, the second compensator 322 can be configured such that the charge change compensation coefficient comp_rate increases with the increase of the first overpotential ratio Vds_rate. Furthermore, the second compensator 322 can be configured such that the charge change compensation coefficient comp_rate increases with the increase of the charge change rate Qm_rate. Therefore, the second compensator 322 can effectively reflect changes in full-charge capacity, thereby improving the accuracy of the state of charge estimation.

[0126] Figure 4 A battery state of charge estimation device 400 according to another embodiment of the present invention is shown.

[0127] Figure 4 The battery state of charge estimation device 400 shown is... Figure 3 The difference in the battery state-of-charge estimation device 300 shown is that it does not use the third coulomb counter 327. Since the battery state-of-charge estimation device 400 does not use the third coulomb counter 327, it does not calculate the second predicted charge quantity Qm. The second compensator 322 can use the first predicted charge quantity Qe instead of the second predicted charge quantity Qm to calculate the charge change compensation coefficient comp_rate. For example, when calculating the rate of change of charge Qm_rate in Equation 11, the first predicted charge quantity Qe can be used instead of the second predicted charge quantity Qm. According to... Figure 4 The battery state of charge estimation device 400 shown can more easily implement the compensator 420 and reduce power consumption because it does not use the third coulomb counter 327.

[0128] Figure 5 A battery state-of-charge estimation method according to an embodiment of the present invention is shown. Figure 5The battery state-of-charge estimation method shown can be derived from the reference. Figures 1 to 4 The battery state of charge estimation device shown is used to perform this.

[0129] refer to Figure 5 The steps can be executed sequentially: accumulating the battery current Im to calculate the first charge change ΔQ (S510), compensating for the first charge change ΔQ to calculate the second charge change ΔQ_comp (S520), accumulating the second charge change ΔQ_comp to calculate the first predicted charge Qe (S530), and estimating the battery's state of charge based on the first predicted charge Qe (S540).

[0130] According to the embodiment, in the step of calculating the second charge change ΔQ_comp by compensating for the first charge change ΔQ (S520), the predicted open circuit voltage OCVe is calculated using the first predicted charge Qe, and the first charge change ΔQ is compensated using the predicted open circuit voltage OCVe, thereby calculating the second charge change ΔQ_comp.

[0131] Figure 6 A battery state-of-charge estimation method according to another embodiment of the present invention is shown. Figure 6 The battery state-of-charge estimation method shown can be derived from the reference. Figures 1 to 4 The battery state of charge estimation device shown is used to perform this.

[0132] First, the battery voltage Vm and battery current Im information can be obtained (S611). Conventional current sensing units such as current sensing resistors or current transformers can be used to detect the battery current Im, but it is not limited to these.

[0133] In step S612, the first charge change ΔQ can be calculated. The calculation of the first charge change ΔQ can be performed by the first coulomb counter 110 described above.

[0134] Steps S611 and S612 can correspond to Figure 5 Step S510.

[0135] Next, the magnitude of the battery current Im is compared with the first threshold TH1 (S621). When the magnitude of the battery current Im is greater than the first threshold TH1, proceed to step S624. When the magnitude of the battery current Im is less than the first threshold TH1, proceed to step S622.

[0136] When the battery current Im is less than the first threshold TH1, the fourth charge change ΔQ_track can be calculated in step S622, and the second charge change ΔQ_comp can be calculated using the fourth charge change ΔQ_track in step S623. Steps S622 and S623 can be executed by the first compensator, and the specific calculation methods for the fourth charge change ΔQ_track and the second charge change ΔQ_comp can apply the aforementioned content related to the first compensator.

[0137] When the battery current Im is greater than the first threshold TH1, the charge change compensation coefficient comp_rate can be calculated in step S624, and the second charge change ΔQ_comp can be calculated using the charge change compensation coefficient comp_rate in step S625. Steps S624 and S625 can be performed by the second compensator, and the specific calculation methods for the charge change compensation coefficient comp_rate and the second charge change ΔQ_comp can apply the aforementioned content related to the second compensator.

[0138] Steps S621 to S625 can correspond to Figure 5 The S520 steps.

[0139] Next, as step S630, the first predicted charge amount Qe can be calculated by accumulating the second charge change ΔQ_comp compensated by step S623 or S625. Step S630 can be performed by the aforementioned second coulomb counter.

[0140] Next, as in step S640, the battery's state of charge can be estimated based on the first predicted charge amount Qe. The battery's state of charge can be represented by the SOC (state of charge), and the SOC can be calculated based on the value obtained by dividing the first predicted charge amount Qe by the design capacity Qd.

[0141] Figure 7 A battery state-of-charge estimation method according to another embodiment of the present invention is shown. Figure 7 Showing more details Figure 6 Steps S622 to S625.

[0142] first, Figure 6 Steps S622 and S623 can be changed to Figure 7 Steps S722 to S725.

[0143] As in step S722, it can be determined whether the battery voltage Vm is less than the predicted open circuit voltage OCVe. If the battery voltage Vm is less than the predicted open circuit voltage OCVe, then proceed to step S723; otherwise, proceed to step S724.

[0144] When the battery voltage Vm is less than the predicted open-circuit voltage OCVe, the fourth charge change ΔQ_track can be calculated in step S723 using the method described in Formula 6 above. In this case, since the predicted open-circuit voltage OCVe follows the battery voltage Vm, the accumulated error caused by the coulomb counter can be reduced.

[0145] When the battery voltage Vm is greater than the predicted open circuit voltage OCVe, the fourth charge change ΔQ_track is set to '0' in step S724, so that the predicted open circuit voltage OCVe remains unchanged.

[0146] then, Figure 6 Steps S624 and S625 can be changed to Figure 7 Steps S726 to S729.

[0147] In step S726, it can be determined whether the first overpotential prediction value Vds_e is greater than the first overpotential reference value Vds_ref. If the first overpotential prediction value Vds_e is greater than the first overpotential reference value Vds_ref, then proceed to step S727; otherwise, proceed to step S728.

[0148] When the predicted first overpotential value Vds_e is greater than the reference first overpotential value Vds_ref, the charge change compensation coefficient comp_rate can be calculated in step S727 using methods such as mathematical formulas 7 to 12. In this case, according to the embodiment, the charge change compensation coefficient comp_rate increases as the first overpotential ratio Vds_rate increases. Furthermore, according to the embodiment, the charge change compensation coefficient comp_rate increases as the charge change rate Qm_rate increases. Therefore, the change in full-charge capacity can be effectively reflected, thereby improving the accuracy of the state of charge estimation.

[0149] When the first overpotential prediction value Vds_e is not greater than the first overpotential reference value Vds_ref, the charge change compensation coefficient comp_rate can be set to '1' in step S728. That is, when the first overpotential prediction value Vds_e is not greater than the first overpotential reference value Vds_ref, the second charge change ΔQ_comp can be the same as the first charge change ΔQ.

[0150] According to an embodiment, the aforementioned battery state-of-charge estimation device can be implemented in software and can execute its functions via a computing device such as a CPU while stored in a computer-readable storage medium (memory, etc.). In this case, the various elements within the battery state-of-charge estimation device can be implemented as separate modules within the software implementing the device for differentiation, or, depending on the situation, implemented as a mixture of functions within the software without differentiation. According to an embodiment, the battery state-of-charge estimation device can be implemented in hardware using devices such as ASICs (Application Specific Integrated Circuits) or FPGAs (Field Programmable Gate Arrays).

[0151] For the terms "comprising," "consisting of," or "having," unless specifically stated otherwise, they indicate that the corresponding constituent element may be included, but do not exclude other constituent elements, and should be understood as capable of further including other constituent elements. Unless otherwise defined, all terms, including technical and scientific terms, have the same meaning as commonly understood by those skilled in the art. Commonly used terms, such as those defined in dictionaries, should be interpreted as consistent with their meaning in the relevant technical context, and should not be interpreted in an ideal or overly formal sense unless explicitly defined by the present invention.

[0152] The above description is merely an illustrative example of the technical concept of the present invention. Those skilled in the art can make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in this invention are not intended to limit the technical concept of the present invention, but rather to illustrate it, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of this invention should be interpreted by the appended claims, and all technical concepts within their equivalent scope should be understood to be included within the scope of the claims of this invention.

Claims

1. A battery state-of-charge estimation device, comprising: The first coulomb counter accumulates the battery current (Im) in each specified period to calculate the first charge change (ΔQ) for each period. A compensator that compensates for the first charge change (ΔQ) to calculate a second charge change (ΔQ_comp); A second coulomb counter is used to calculate the first predicted charge (Qe) by accumulating the second charge change (ΔQ_comp); and A state-of-charge estimator that estimates the battery's state of charge based on the first predicted charge (Qe). The compensator uses the first predicted charge amount (Qe) to calculate the predicted open circuit voltage (OCVe), and uses the predicted open circuit voltage (OCVe) to calculate the second charge change (ΔQ_comp).

2. The battery state of charge estimation device according to claim 1, characterized in that, When calculating the predicted open circuit voltage (OCVe) using the first predicted charge (Qe), a first lookup table containing data on the relationship between the open circuit voltage (OCV) and charge (Q) corresponding to the battery is used.

3. The battery state of charge estimation device according to claim 1, characterized in that, When the magnitude of the battery current (Im) is less than the first threshold, the compensator compensates for the first charge change (ΔQ) to reduce the difference between the predicted open circuit voltage (OCVe) and the battery terminal voltage (Vm), thereby calculating the second charge change (ΔQ_comp).

4. The battery state of charge estimation device according to claim 3, characterized in that, The second charge change (ΔQ_comp) is calculated based on the value obtained by subtracting the predicted open circuit voltage (OCVe) from the battery terminal voltage (Vm) and multiplying it by a first constant (C1).

5. The battery state of charge estimation device according to claim 4, characterized in that, The first constant (C1) is predetermined based on the internal resistance value of the battery.

6. The battery state of charge estimation device according to claim 1, characterized in that, When the magnitude of the battery current (Im) is greater than the second threshold, the compensator compensates for the first charge change (ΔQ) to reduce the difference between the first overpotential prediction value (Vds_e) and the first overpotential reference value (Vds_ref), thereby calculating the second charge change (ΔQ_comp).

7. The battery state of charge estimation device according to claim 6, characterized in that, The first overpotential prediction value (Vds_e) is calculated based on the value obtained by subtracting the predicted open circuit voltage (OCVe) from the battery terminal voltage (Vm), and the first overpotential reference value (Vds_ref) is calculated using a second lookup table containing information on the internal resistance (R) and the second overpotential (Vov) of the corresponding battery.

8. The battery state of charge estimation device according to claim 7, characterized in that, The information on the internal resistance (R) and second overpotential (Vov) of the battery contained in the second lookup table was obtained through experiments of applying intermittent constant current pulses to a battery in an unaged state at room temperature.

9. The battery state of charge estimation device according to claim 6, characterized in that, The compensator calculates the charge change compensation coefficient (comp_rate), and multiplies the charge change compensation coefficient (comp_rate) by the first charge change (ΔQ) to calculate the second charge change (ΔQ_comp).

10. The battery state of charge estimation device according to claim 9, characterized in that, When the first overpotential prediction value (Vds_e) is less than the first overpotential reference value (Vds_ref), the charge change compensation coefficient (comp_rate) is set to 1.

11. The battery state of charge estimation device according to claim 9, characterized in that, When the first overpotential prediction value (Vds_e) is greater than the first overpotential reference value (Vds_ref), the charge change compensation coefficient (comp_rate) also increases as the first overpotential ratio (Vds_rate) increases.

12. The battery state of charge estimation device according to claim 11, characterized in that, The first overpotential ratio (Vds_rate) is proportional to the value obtained by dividing the first overpotential prediction value (Vds_e) by the first overpotential reference value (Vds_ref).

13. The battery state of charge estimation device according to claim 9, characterized in that, When the first overpotential prediction value (Vds_e) is greater than the first overpotential reference value (Vds_ref), the charge change compensation coefficient (comp_rate) also increases as the charge change rate (Qm_rate) increases.

14. The battery state of charge estimation device according to claim 10, characterized in that, The compensator further includes a third coulomb counter that accumulates the first charge change (ΔQ) to calculate the second predicted charge (Qm). The charge change rate (Qm_rate) is determined based on the change rate of the second predicted charge (Qm).

15. A battery state of charge estimation method, executed by a battery state of charge estimation device, the method comprising: The steps for calculating the first charge change (ΔQ) by accumulating the battery current (Im); The step of compensating for the first charge change (ΔQ) to calculate the second charge change (ΔQ_comp); The step of calculating the first predicted charge (Qe) by summing the second charge change (ΔQ_comp); as well as The step of estimating the battery's state of charge based on the first predicted charge (Qe) In the step of calculating the second charge change (ΔQ_comp) by compensating for the first charge change (ΔQ), the predicted open circuit voltage (OCVe) is calculated using the first predicted charge (Qe), and the first charge change (ΔQ) is compensated using the predicted open circuit voltage (OCVe) to calculate the second charge change (ΔQ_comp).

16. The battery state of charge estimation method according to claim 15, characterized in that, In the step of calculating the second charge change (ΔQ_comp) by compensating for the first charge change (ΔQ), when the magnitude of the battery current (Im) is less than the first threshold (TH1), the first charge change (ΔQ) is compensated to reduce the difference between the predicted open circuit voltage (OCVe) and the battery terminal voltage (Vm), thereby calculating the second charge change (ΔQ_comp).

17. The battery state of charge estimation method according to claim 16, characterized in that, The second charge change (ΔQ_comp) is calculated based on the value obtained by subtracting the predicted open circuit voltage (OCVe) from the battery terminal voltage (Vm) and multiplying it by the first constant C1.

18. The battery state-of-charge estimation method according to claim 15, characterized in that, In the step of calculating the second charge change (ΔQ_comp) by compensating for the first charge change (ΔQ), when the magnitude of the battery current (Im) is greater than the second threshold, the first charge change (ΔQ) is compensated to reduce the difference between the first overpotential prediction value (Vds_e) and the first overpotential reference value (Vds_ref), thereby calculating the second charge change (ΔQ_comp).

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