Apparatus and method for compensating OCV of battery

Abstract

To provide an apparatus and method for compensating an open-circuit voltage (OCV) of a battery.SOLUTION: An apparatus for compensating an OCV (open-circuit voltage) of a battery includes a voltage sensor configured to detect a voltage of a battery cell, and a processor configured to extract a voltage value and a SOC (state-of-charge) value of a peak within a preset voltage section for each cycle based on a voltage value of the battery cell detected by the voltage sensor each time the preset set cycle elapses and compensate an OCV using the SOC value for each peak and a voltage variation amount of the peak.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for correcting a battery OCV. [Background technology]

[0002] BMS (Battery Management System) is equipped with an algorithm for estimating the battery state. The algorithm estimates the internal state of the battery using information that can be measured externally from the battery (voltage, current, temperature, etc.). The algorithm is also expanded to various elemental technologies (capacity estimation, quick charging, diagnostic functions, etc.) that utilize the estimated information.

[0003] The algorithm uses various elemental technologies to provide users with more accurate information and detect and prevent abnormal phenomena such as battery fires and explosions in advance. To achieve this, the algorithm must accurately estimate the internal state of the battery even in diverse or harsh environments, and precise model construction and control must be carried out to prevent errors from occurring.

[0004] However, the accuracy of the algorithm's estimation may decrease because the direction and degree of aging of the battery may change depending on the usage environment. In addition, errors in the estimated capacity accumulate every time the battery is exposed to harsh environments, and the error deviation of the capacity information that decreases due to deterioration may become larger as time passes. As a result, the possibility of battery accidents increasing or problems such as reduced battery usage efficiency may occur.

[0005] The background art of the present invention is disclosed in Korean Patent Publication No. 10-0878123 (2009.01.05) entitled "Battery Cell State and Parameter Estimation System and Method." Summary of the Invention [Problem to be solved by the invention]

[0006] An object of one aspect of the present invention is to provide an apparatus and method for correcting a battery OCV, which more simply and precisely corrects an OCV (Open Circuit Voltage) with respect to a State Of Charge (SOC) according to an aging direction of a battery cell. [Means for solving the problem]

[0007] According to an aspect of the present invention, there is provided a battery OCV correction device including: a voltage sensor for detecting a voltage of a battery cell; and a processor for extracting a peak voltage value and a State Of Charge (SOC) value within a preset voltage range for each cycle based on a voltage value of the battery cell detected by the voltage sensor every time a preset cycle elapses, and correcting an Open Circuit Voltage (OCV) using the SOC value for each peak and an amount of change in the peak voltage.

[0008] The processor of the present invention is characterized in that, when a plateau section appears in the battery cell, the processor extracts the peak voltage value and the SOC value within the voltage section.

[0009] The processor of the present invention is characterized in that it extracts the peak in a voltage section where the capacity change / voltage change is equal to or greater than a preset reference value by using ICA (Incremental Capacity Analysis) during a constant current charging or discharging process of the battery cell.

[0010] The processor of the present invention is characterized in that it adds the voltage change amount relative to the SOC value to an OCV value.

[0011] The processor of the present invention is characterized in that it extracts a voltage change function with respect to the SOC value, and calculates the voltage change with respect to the SOC value by using the voltage change function.

[0012] The processor of the present invention is characterized in that it extracts the voltage change amount function using at least one of constant processing, an interpolation / extrapolation method, a cut method, and curve fitting according to the number of the peaks.

[0013] The processor of the present invention is characterized in that, if the number of the peaks is one, the processor processes the voltage change amount function as a constant.

[0014] The processor of the present invention is characterized in that, if there are a plurality of peaks, the processor extracts the voltage change function through at least one of an interpolation / extrapolation method, a cut method, and curve fitting.

[0015] According to an aspect of the present invention, a method for correcting an OCV of a battery includes: extracting a peak voltage value and an SOC value within a preset voltage range for each cycle based on a voltage value of a battery cell sensed by a voltage sensor by a processor; and correcting an OCV by using the SOC value for each peak and an amount of voltage change of the peak by the processor.

[0016] In the step of extracting a peak voltage value and a SOC value within the voltage range for each cycle, the processor may extract the peak voltage value and the SOC value within the voltage range when a plateau range appears in the battery cell.

[0017] In the step of extracting the peak voltage value and SOC value in the voltage range for each cycle, the processor extracts the peak in a voltage range where the capacity change amount / voltage change amount is equal to or greater than a preset reference value by using an incremental capacity analysis (ICA) during a constant current charging or discharging process of the battery cell.

[0018] In the step of correcting the OCV, the processor may add the voltage change amount relative to the SOC value to the OCV value.

[0019] In the step of correcting the OCV, the processor may extract a voltage change function for the SOC value, and calculate the voltage change for the SOC value using the voltage change function.

[0020] In the step of correcting the OCV of the present invention, the processor extracts the voltage change function using at least one of a constant processing method, an interpolation / extrapolation method, a cut method, and a curve fitting according to the number of the peaks.

[0021] In the step of correcting the OCV of the present invention, the processor may process the voltage change amount function as a constant if the number of the peaks is one.

[0022] In the step of correcting the OCV of the present invention, if there are a plurality of peaks, the processor extracts the voltage change function through at least one of an interpolation / extrapolation method, a cutoff method, and a curve fitting method. Effect of the Invention

[0023] SUMMARY OF THE DISCLOSURE An apparatus and method for correcting a battery OCV according to an aspect of the present invention can more simply and accurately correct an OCV relative to a SOC according to an aging direction of a battery cell, and can improve the performance of an algorithm for estimating the state of a battery cell. [Brief description of the drawings]

[0024] [Figure 1] 1 is a block diagram of a battery OCV correction device according to an embodiment of the present invention. [Diagram 2] 4 is a graph showing a voltage of a battery cell relative to a capacity of the battery cell according to an embodiment of the present invention. [Diagram 3] 1 is a graph showing a peak shift in a plateau section according to an embodiment of the present invention. [Figure 4] 4 is a graph showing voltage changes before and after aging according to an embodiment of the present invention; [Diagram 5]1 is a diagram showing a voltage change function and a corrected OCV with respect to SOC according to an embodiment of the present invention. [Figure 6] 1 is a diagram showing an OCV to which a voltage change function according to an embodiment of the present invention is applied. [Figure 7] 1 is a diagram illustrating an example of voltage change extraction according to an embodiment of the present invention. [Figure 8] 4 is a flowchart of a battery OCV correction method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, a battery OCV correction device and method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the process, the thickness of lines and the size of components illustrated in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, and may vary depending on the intention or practice of a user or operator. Therefore, the definitions of such terms should be based on the overall content of this specification.

[0026] FIG. 1 is a block diagram of a battery OCV correction device according to an embodiment of the present invention.

[0027] Referring to FIG. 1, a battery OCV correction device according to an embodiment of the present invention includes a voltage sensor 200, a relay 100, a current sensor 300, a charge / discharge controller 400 and a processor 500.

[0028] The battery 10 can be connected in series with the terminals of an external device (not shown).

[0029] The battery 10 can supply power to an external device and can be charged by receiving power from an external device.

[0030] The external device may be a load of the electric vehicle or hybrid vehicle, but the type of the external device is not particularly limited.

[0031] The battery 10 may include a plurality of battery cells 20 connected in series or parallel.

[0032] The battery cell 20 may be at least one of a lithium ion battery and a lithium polymer battery.

[0033] The relay 100 controls the electrical connection between the battery 10 and the external device. That is, the relay 100 can be turned on by a control signal from the processor 500 to electrically connect the battery 10 to the external device. At this time, the battery 10 can supply power to the external device or can be charged by receiving power from the external device. Alternatively, the relay 100 can be turned off by a control signal from the processor 500 to electrically disconnect the battery 10 from the external device.

[0034] The relay 100 may be installed between the positive terminal of the battery 10 and an external device. Alternatively, the relay 100 may be installed between the negative terminal of the battery 10 and an external device. The installation position of the relay 100 is not particularly limited.

[0035] The voltage sensors 200 may be connected to the positive and negative electrodes of the battery cells 20, respectively.

[0036] The voltage sensor 200 can sense the voltage of the battery cell 20 and input it to the processor 500 .

[0037] The current sensor 300 may be connected between the negative terminal of the battery cell 20 and an external device.

[0038] The current sensor 300 can sense the current during charging or discharging of the battery cell 20 and input the sensed current to the processor 500 .

[0039] The current sensor 300 may be a Hall current transformer (Hall CT) that measures a current using a Hall element and outputs an analog current signal corresponding to the measured current.

[0040] The charge / discharge controller 400 controls the charging / discharging of the battery 10 .

[0041] The charge / discharge controller 400 can control the constant current charging or discharging of the battery 10 according to a control signal from the processor 500. The charge / discharge controller 400 includes a plurality of switch elements for constant current charging or discharging of the battery 10, and can control the flow of current during charging or discharging according to the switching state of these switch elements. The switch elements may be MOSFETs, but are not limited thereto.

[0042] The processor 500 can identify the battery cell 20 in which a plateau section appears by using the voltage value of each battery cell 20 sensed by the voltage sensor 200 .

[0043] In addition, the processor 500 can extract a peak voltage value and a State Of Charge (SOC) value within a preset voltage range based on the voltage value of the battery cell 20 where the plateau section appears every time a preset cycle elapses.

[0044] The cycle may be a charge cycle or a discharge cycle.

[0045] The processor 500 can correct an OCV (Open Circuit Voltage) using the peak SOC value and the peak voltage change amount.

[0046] More specifically, the processor 500 can control the relay 100 to electrically connect the battery 10 to an external device.

[0047] The processor 500 can control the charge / discharge controller 400 to control the charge / discharge of the battery 10 .

[0048] In addition, the processor 500 may determine whether a plateau section appears for each battery cell 20 based on the voltage of each battery cell 20 sensed by the voltage sensor 200 in the corresponding cycle each time a preset cycle elapses.

[0049] The set cycle is a cycle that can adequately determine a voltage change at a peak, which will be described later. The set cycle is not particularly limited. The peak will be described later.

[0050] The plateau section is a section where the voltage does not change significantly during charging and discharging.

[0051] To check whether a plateau section appears, the processor 500 may first extract the amount of change in the voltage of the battery cell 20 during charging and discharging of the battery 10 through the charge / discharge controller 400. The processor 500 may determine whether the amount of change in the voltage of the corresponding battery cell 20 is equal to or less than a critical value, and may determine that the corresponding battery cell 20 has a plateau section if the amount of change in the voltage of the battery cell 20 is equal to or less than the critical value.

[0052] The critical value is a voltage change amount for determining whether a plateau section appears. If the voltage change amount of the battery cell 20 is equal to or less than the critical value, it may be determined that the battery cell 20 has a plateau section.

[0053] The processor 500 repeatedly checks whether a plateau section exists for each battery cell 20 every time a set cycle elapses.

[0054] The processor 500 performs an incremental capacity analysis (ICA) on the battery cell 20 in which the plateau section appears.

[0055] ICA is a method for more precisely estimating the voltage or capacity of the battery cell 20. Since ICA is obvious to those skilled in the art, a detailed description thereof will be omitted here.

[0056] The processor 500 uses the ICA to determine whether the capacitance change amount / voltage change amount is equal to or greater than a preset reference value, extracts a voltage section in which the capacitance change amount / voltage change amount is equal to or greater than the reference value, and then sets a peak in the extracted voltage section.

[0057] Here, the reference value is a capacitance change amount / voltage change amount that is set in advance to set a peak.

[0058] FIG. 2 is a graph showing the voltage of a battery cell versus the capacity of the battery cell according to an embodiment of the present invention, and FIG. 3 is a graph showing a peak shift in a plateau section according to an embodiment of the present invention.

[0059] Generally, the battery cell 20 in which a plateau appears has a larger capacity change than a voltage change, so the processor 500 can set the peaks as shown in FIG.

[0060] The processor 500 stores the voltage and SOC value at which the peak was set.

[0061] In FIG. 2, the dashed line is capacitance versus voltage at the 50th cycle, and the solid line is capacitance versus voltage at the 200th cycle.

[0062] By performing ICA on this battery cell 20, it is possible to extract peaks as shown in Fig. 3. Each circle in Fig. 3 illustrates a peak at the 50th cycle and a peak at the 200th cycle.

[0063] The peak shifts to the lower right due to factors such as a decrease in maximum capacity or an increase in voltage as the number of cycles of the battery cell 20 increases or as the battery cell 20 ages.

[0064] That is, referring to FIG. 3, it can be seen that the peak voltage at the 50th cycle is shifted to the lower right at the 200th cycle, after 150 cycles have elapsed.

[0065] Therefore, the processor 500 can calculate the peak voltage change, which is the amount that the peak has been shifted.

[0066] FIG. 4 is a graph showing voltage changes before and after aging according to an embodiment of the present invention.

[0067] 4, when two peaks are set in the battery cell 20, two voltage changes dV1 and dV2 can be obtained from the voltages of the two peaks at the 50th cycle and the voltages of the two peaks at the 200th cycle after 150 cycles have passed. dV1 is about 0.0033 (3.32519-3.32193)V, and dV2 is about 0.0053 (3.35-3.34474)V.

[0068] Subsequently, the processor 500 calculates a voltage change function for SOC using the previously stored SOC values ​​for each cycle and the voltage changes between the voltages for those cycles.

[0069] That is, processor 500 extracts a voltage change function for SOC value using two SOC values ​​at the 50th cycle, two SOC values ​​at the 200th cycle, and the voltage change between the voltage at the 50th cycle and the voltage at the 200th cycle.

[0070] The processor 500 uses the extracted voltage change function to calculate the voltage change for each SOC value.

[0071] The processor 500 sums the calculated voltage change for each SOC to the OCV of the existing SOC value.

[0072] FIG. 5 is a graph showing a voltage change function and a corrected OCV with respect to SOC according to an embodiment of the present invention.

[0073] Referring to Figure 5, the voltage change function is y=0.01*x-0.0017. The two points are dV1 (0.0033) and dV2 (0.0053).

[0074] Thus, the processor 500 calculates the voltage change amount for the SOC value using the voltage change amount function. The processor 500 can correct the OCV by adding the calculated voltage change amount for the SOC value to the existing OCV.

[0075] FIG. 6 is a diagram showing an OCV to which a voltage change function according to an embodiment of the present invention is applied.

[0076] Referring to FIG. 6, a corrected OCV is shown in which the voltage change between dV1 and dV2 is added to the existing OCV.

[0077] Meanwhile, the processor 500 can extract the voltage change function in various ways depending on the number of peaks. The processor 500 can use at least one of a constant processing method, an interpolation / extrapolation method, a cut method, and a curve fitting method.

[0078] FIG. 7 is a diagram showing an example of voltage change extraction according to an embodiment of the present invention.

[0079] Referring to FIG. 7, if there is one peak, the processor 500 processes the voltage change amount function as a constant.

[0080] If there are two peaks, the processor 500 extracts a voltage change function using an interpolation / extrapolation method or curve fitting.

[0081] If there are three or more peaks, the processor 500 can use the interpolation / extrapolation method, the interpolation / extrapolation and cut method, or the curve fitting method.

[0082] Hereinafter, a method for correcting a battery OCV according to an embodiment of the present invention will be described with reference to FIG.

[0083] FIG. 8 is a flowchart of a battery OCV correction method according to an embodiment of the present invention.

[0084] Referring to FIG. 8, the processor 500 may determine whether a plateau section appears for each battery cell 20 based on the voltage of each battery cell 20 sensed by the voltage sensor 200 every time a preset number of cycles, for example 150 cycles, have elapsed (S100).

[0085] To this end, the processor 500 determines whether the amount of change in the voltage of the battery cell 20 in the corresponding cycle is below a critical value. If the amount of change in the voltage of the battery cell 20 is below the critical value, the processor 500 can determine that a plateau section appears in the corresponding battery cell 20.

[0086] The processor 500 may perform ICA on the battery cell 20 in which the plateau section appears, and set the peak of the voltage section in which the capacity change amount / voltage change amount is equal to or greater than a preset reference value (S200).

[0087] By setting the peak, the processor 500 can store the voltage and SOC value at the point where the peak is set (S300).

[0088] When the voltage and SOC value at the peak points in a plurality of set cycles are stored, the processor 500 can calculate the voltage change amount using the peak voltage in each cycle (S400).

[0089] For example, if two peaks are set in the 50th cycle and the voltages of the corresponding peaks are shifted in the 200th cycle, two voltage changes dV1 and dV2 can be obtained from the voltages of the two peaks in the 50th cycle and the voltages of the two peaks in the 200th cycle after 150 cycles have passed.

[0090] The processor 500 extracts a voltage change function with respect to the SOC using the prestored SOC values ​​in each cycle and the voltage changes between the voltages in these cycles (S500).

[0091] That is, processor 500 extracts a voltage change function for SOC value using two SOC values ​​at the 50th cycle, two SOC values ​​at the 200th cycle, and the voltage change between the voltage at the 50th cycle and the voltage at the 200th cycle.

[0092] In this case, the processor 500 can use at least one of constant processing, interpolation / extrapolation, cutoff, and curve fitting depending on the number of peaks.

[0093] Next, the processor 500 calculates a voltage change for each SOC value using the extracted voltage change function, and adds the calculated voltage change for each SOC to the OCV of the existing SOC value to correct the OCV (S700).

[0094] The implementations described herein may be embodied, for example, as a method or process, an apparatus, a software program, a data stream, or a signal. Even if discussed in the context of only one form of implementation (e.g., discussed only as a method), the implementation of the discussed features may also be embodied in other forms (e.g., an apparatus or a program). An apparatus may be embodied in appropriate hardware, software, firmware, and the like. A method may be embodied in an apparatus, such as, for example, a processor, which generally refers to a processing device including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices, such as computers, cell phones, portable / personal digital assistants ("PDAs"), and other devices that facilitate communication of information between end-users.

[0095] Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely illustrative, and those skilled in the art will recognize that various modifications and equivalent embodiments are possible. Therefore, the true technical scope of the present invention should be determined by the following claims. [Explanation of symbols]

[0096] 10: Battery 20: Battery cell 100: Relay 200: Voltage sensor 300: Current sensor 400: Charge / discharge controller 500: Processor

Claims

1. a voltage sensor for sensing a voltage of the battery cell; and a processor for extracting a peak voltage value and a State Of Charge (SOC) value within a preset voltage range for each cycle based on a voltage value of the battery cell sensed by the voltage sensor every time a preset set cycle elapses, and for correcting an Open Circuit Voltage (OCV) using the SOC value and the amount of change in the peak voltage.

2. The processor The battery OCV correction device according to claim 1 , wherein when a plateau section appears in the battery cell, the peak voltage value and the SOC value in the voltage section are extracted.

3. The processor 2. The battery OCV correcting device of claim 1, wherein the peak is extracted in a voltage section where a capacity change amount / voltage change amount is equal to or greater than a preset reference value by using an incremental capacity analysis (ICA) during a constant current charging or discharging process of the battery cell.

4. The processor The battery OCV correction device according to claim 1 , further comprising: adding the voltage change amount relative to the SOC value to an OCV value.

5. The processor The battery OCV correction device according to claim 4 , further comprising: extracting a voltage change function for the SOC value; and calculating the voltage change for the SOC value using the voltage change function.

6. The processor The battery OCV correction device according to claim 5 , wherein the voltage change function is extracted using at least one of a constant processing method, an interpolation / extrapolation method, a cut method, and a curve fitting method according to the number of the peaks.

7. The processor The battery OCV correction device according to claim 6 , wherein if the number of the peaks is one, the voltage change amount function is processed as a constant.

8. The processor The battery OCV correcting device according to claim 6, wherein if there are a plurality of peaks, the voltage change function is extracted through at least one of an interpolation / extrapolation method, a cut method, and a curve fitting method.

9. A processor extracts a peak voltage value and an SOC value within a preset voltage range for each cycle based on a voltage value of the battery cell sensed by the voltage sensor; and The processor corrects an OCV by using the peak-specific SOC value and the peak voltage change amount.

10. extracting a peak voltage value and a peak SOC value for each cycle within the voltage range; The battery OCV correction method of claim 9 , wherein the processor extracts the peak voltage value and the SOC value in the voltage range when a plateau section appears in the battery cell.

11. extracting a peak voltage value and a peak SOC value for each cycle within the voltage range; 10. The battery OCV correction method of claim 9, wherein the processor extracts the peak in a voltage section where a capacity change amount / voltage change amount is equal to or greater than a preset reference value by using incremental capacity analysis (ICA) during a constant current charging or discharging process of the battery cell.

12. In the step of correcting the OCV, The method of claim 9 , wherein the processor sums the voltage change relative to the SOC value to an OCV value.

13. In the step of correcting the OCV, The method of claim 12 , wherein the processor extracts a voltage change function with respect to the SOC value, and calculates the voltage change with respect to the SOC value using the voltage change function.

14. In the step of correcting the OCV, The method of claim 13, wherein the processor extracts the voltage change function using at least one of a constant processing method, an interpolation / extrapolation method, a cut method, and a curve fitting method according to the number of the peaks.

15. In the step of correcting the OCV, The method of claim 14, wherein the processor processes the voltage change amount function as a constant if the number of the peaks is one.

16. In the step of correcting the OCV, The method of claim 14, wherein the processor extracts the voltage change function through at least one of an interpolation / extrapolation method, a cut method, and a curve fitting method if there are a plurality of peaks.

Images