Battery cell balancing device and method, and battery management system

Abstract

The present disclosure relates to a battery cell balancing apparatus and method, and a battery management system, and provides a battery cell balancing apparatus and method for balancing a battery cell even when an abnormality has occurred in an internal circuit of a battery management system (BMS). A mechanism can also extend the service life of the battery pack by allowing a balancing function to be used to the maximum within a range in which cell voltage measurement errors can be compensated. To this end, the present disclosure provides a configuration to determine whether an abnormality has occurred in an RC circuit of a BMS based on a cell voltage of a battery cell measured by the RC circuit, and to control a switching time of a balance switch to compensate for a cell voltage measurement error caused by the abnormality in the RC circuit.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an apparatus and method for controlling balancing of battery cells and a battery management system. BACKGROUND

[0002] A battery pack includes battery cells and a peripheral circuit including a charge / discharge circuit. The peripheral circuit is manufactured as a printed circuit board and then connected to the battery cells. When an external power source is connected to external terminals of the battery pack, the battery cells are charged, and when a load is connected to the external terminals, the battery cells are discharged. The charge / discharge circuit controls charging / discharging of the battery cells between the external terminals and the battery cells. Generally, a plurality of battery cells are connected in series and in parallel according to a consumption capacity of the load.

[0003] The above-described information disclosed in this BACKGROUND section is to enhance understanding of the background of the present disclosure, and thus it can include information that does not constitute the related (or prior) art. SUMMARY

[0004] The present disclosure aims to provide a battery cell balancing apparatus and method and a battery management system that increase a service life of a battery pack by maximizing use of a balancing function within a range in which a cell voltage measurement error can be compensated for even when an abnormality has occurred in a circuit for battery cell balancing and cell voltage detection applied to the battery pack.

[0005] However, the objectives that the present disclosure intends to achieve are not limited to the above-described objectives, and other objectives not described can be clearly understood by those skilled in the art through the following description.

[0006] A battery cell balancing apparatus according to one embodiment of the present disclosure for solving the above-described technical problem includes a balancing circuit including a balancing switch disposed on a discharge path formed when balancing of battery cells is performed, an RC circuit connected between the battery cells and the balancing circuit to measure a cell voltage of the battery cells, and a processor that measures the cell voltage of the battery cells through the RC circuit after completion of the balancing of the battery cells and controls a switching time of the balancing switch to compensate for a cell voltage measurement error caused by an abnormality in the RC circuit when it is determined that the abnormality has occurred in the RC circuit based on the measured cell voltage.

[0007] In some embodiments, the processor is configured to measure the cell voltage through the RC circuit after a pre-defined delay time from a point in time when the balancing switch is turned off when the balancing of the battery cells is completed when measuring the cell voltage.

[0008] In some embodiments, the delay time is pre-defined based on a time constant of the RC circuit when no abnormality occurs in the RC circuit.

[0009] In some embodiments, the cell voltage measurement error is defined as the difference between a first cell voltage measured before balancing of the cell is performed and a second cell voltage measured after a delay from the point when balancing of the cell is completed when the balancing switch is turned off.

[0010] In some embodiments, the RC circuit includes a resistor connected in the path through which the current drawn from the battery cell passes, and a capacitor connected in parallel to the balancing circuit at the node where the resistor and the balancing circuit are connected, and charged by the current drawn from the battery cell; the first cell voltage is the voltage in a steady state formed when the capacitor is charged by the current drawn from the battery cell.

[0011] In some embodiments, when the individual cell voltage measurement error is greater than or equal to a predefined threshold, the processor determines that an anomaly has occurred in the RC circuit.

[0012] In some embodiments, the processor is configured to: when no abnormality occurs in the RC circuit, during the balancing of individual battery cells, turn on the balancing switch for a predefined balancing time, and shorten the balancing time when compensating for individual cell voltage measurement errors.

[0013] In some embodiments, when compensating for individual cell voltage measurement errors, the processor shortens the balancing time by advancing the balancing switch disconnection time to a predefined calibration time.

[0014] In some embodiments, when the operation of advancing the disconnection time of the balance switch by a predefined calibration time is defined as an error compensation operation, the processor repeatedly performs the error compensation operation whenever the battery cell is balanced, until the cell voltage measurement error is less than a predefined threshold.

[0015] In some embodiments, when the shortened balancing time due to repeated error compensation operations is less than or equal to a predefined calibration time, and the cell voltage measurement error remains above or equal to a predefined threshold, the processor stops balancing the cell after the current time point.

[0016] According to some aspects, a battery cell balancing method is provided, which may include: a processor performing battery cell balancing via a balancing circuit, wherein the balancing circuit includes a balancing switch disposed on a discharge path formed during the balancing of the battery cells; after the battery cell balancing is completed, the processor measuring the cell voltage of the battery cell via an RC circuit, wherein the RC circuit is connected between the battery cell and the balancing circuit to measure the cell voltage; the processor determining whether an anomaly has occurred in the RC circuit based on the measured cell voltage; and when an anomaly has been determined to have occurred in the RC circuit, the processor controlling the switching time of the balancing switch to compensate for the cell voltage measurement error caused by the anomaly in the RC circuit.

[0017] In some embodiments, during measurement, the processor measures the individual cell voltage via an RC circuit after a predefined delay time from the point when the balance switch is turned off.

[0018] In some embodiments, the RC circuit includes: a resistor connected in the path of drawing current from the battery cell; and a capacitor connected in parallel to the balancing circuit at the node where the resistor and the balancing circuit are connected and charged by the current drawn from the battery cell; the battery cell balancing method further includes: measuring a first cell voltage of the battery cell by a processor before execution, wherein the first cell voltage is the voltage in a steady state formed when the capacitor is charged by the current drawn from the battery cell when the balancing switch is off.

[0019] In some embodiments, the cell voltage measurement error is defined as the difference between the first cell voltage and the second cell voltage measured after a delay from the point when the cell balancing is completed when the balancing switch is turned off.

[0020] In some embodiments, the processor determines that an anomaly has occurred in the RC circuit when the individual cell voltage measurement error is greater than or equal to a predefined threshold.

[0021] In some embodiments, the processor is configured to: when balancing individual battery cells without an anomaly occurring in the RC circuit, activate the balancing switch for a predefined balancing time; and during compensation, shorten the predefined balancing time.

[0022] In some embodiments, during compensation, the processor shortens the predefined balancing time by advancing the disconnection time of the balancing switch by a predefined calibration time.

[0023] In some embodiments, when the operation of advancing the disconnection time of the balance switch by a predefined calibration time is defined as an error compensation operation, in the compensation, whenever the battery cell is balanced, the processor repeatedly performs the error compensation operation until the cell voltage measurement error is less than a predefined threshold.

[0024] In some embodiments, the method further includes: when the shortened balancing time according to the repeatedly performed error compensation operation is less than or equal to a predefined calibration time, and the cell voltage measurement error remains above or equal to a predefined threshold, the processor stops balancing the battery cells after the current time point.

[0025] According to some aspects, a battery management system is provided, which may include: a balancing circuit including a balancing switch disposed on a discharge path formed during the balancing of battery cells; an RC circuit connected between the battery cells and the balancing circuit to measure the cell voltage of the battery cells; an analog front-end integrated circuit (AFE IC) configured to measure the cell voltage of the battery cells via the RC circuit after the balancing of the battery cells is completed; and a microcontroller unit (MCU) receiving the cell voltage measured by the AFE IC and determining whether an anomaly has occurred in the RC circuit, and when an anomaly has been determined to have occurred in the RC circuit, sending a control signal to the AFE IC for controlling the switching time of the balancing switch, wherein the AFE IC controls the switching time of the balancing switch based on the control signal received from the MCU to compensate for the cell voltage measurement error caused by the anomaly in the RC circuit. Attached Figure Description

[0026] The following accompanying drawings illustrate embodiments of the present disclosure and further describe aspects and features of the invention together with the detailed description of the present disclosure. Therefore, this disclosure should not be construed as limited to the drawings, in which: Figure 1 This is a circuit diagram of a battery cell balancing device according to an embodiment of the present disclosure; Figures 2 to 4 An example of performing battery cell balancing in a battery cell balancing device according to an embodiment of the present disclosure is shown; Figure 5 An example of a cell voltage measurement error caused by an anomaly in the RC circuit of a cell balancing device according to an embodiment of the present disclosure is shown; Figure 6 and Figure 7 An example of error compensation operation of a battery cell balancing device according to an embodiment of the present disclosure is shown; Figure 8 This is a circuit diagram of a battery management system according to an embodiment of the present disclosure; and Figure 9 This is a flowchart of a battery cell balancing method according to an embodiment of the present disclosure. Detailed Implementation

[0027] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims should not be construed as limited to their ordinary or dictionary meanings, but should be interpreted in accordance with the principle that the inventor can be his / her own lexicographer to appropriately define the concepts of the terms so as to best interpret his / her invention, and are therefore consistent with the technical concept and ideas of this disclosure.

[0028] The embodiments described in this specification and the configurations shown in the accompanying drawings are merely some embodiments of this disclosure and do not represent all the technical concepts, aspects, and features of this disclosure. Therefore, it should be understood that various equivalents and modifications may exist at the time of filing this application, which may replace or modify the embodiments described herein.

[0029] It will be understood that when an element or layer is described as being "on," "connected to," or "bonded to" another element or layer, it can be directly on, directly connected to, or bonded to the other element or layer, or one or more intermediary elements or layers may be present. When an element or layer is described as being "directly on," "directly connected to," or "directly bonded to" another element or layer, no intermediary element or layer is present. For example, when a first element is described as being "bonded" or "connected" to a second element, the first element can be directly bonded to or connected to the second element, or the first element can be indirectly bonded to or connected to the second element through one or more intermediary elements.

[0030] In the accompanying drawings, the dimensions of various elements, layers, etc., may be exaggerated for clarity. The same reference numerals denote the same elements. Herein, the term "and / or" includes any and all combinations of one or more of the related items listed. Furthermore, the use of "may" in describing embodiments of this disclosure refers to "one or more embodiments of this disclosure." When expressions such as "at least one of..." and "any one of..." follow a list of elements, they modify the entire list of elements without modifying any individual element in the list. When phrases such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group consisting of A, B, and C," or "at least one selected from A, B, and C" are used to specify a list of elements A, B, and C, the phrase may refer to any and all suitable combinations or subsets of A, B, and C, such as A, B, C, A and B, A and C, B and C, or A, B, and C. In this document, the term "use" and its variations may be considered synonymous with the term "utilize" and its variations, respectively. As used herein, the terms “basically,” “approximately,” and similar terms are used as approximate terms rather than terms of degree, and are intended to explain the inherent biases of measurements or calculations that would be recognized by one of ordinary skill in the art.

[0031] It will be understood that while the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or portion from another. Therefore, the first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.

[0032] For ease of description, spatial relative terms (such as "below," "under," "down," "above," "above," etc.) are used herein to describe the relationship between one element or feature and another element(s) shown in the figures. It will be understood that, in addition to the orientation depicted in the figures, the spatial relative terms are intended to also cover different orientations of the device during use or operation. For example, if the device in the figures is flipped, an element described as "below" or "under" other elements or features will subsequently be oriented "above" or "above" said other elements or features. Thus, the term "below" can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein should be interpreted accordingly.

[0033] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to be limiting of this disclosure. As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the terms “comprising,” “including,” and / or variations thereof, when used in this specification, indicate the presence of the stated features, integers (in whole), steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers (in whole), steps, operations, elements, components, and / or groups thereof.

[0034] Furthermore, any numerical range disclosed and / or described herein is intended to include all subranges with the same numerical precision contained within the described range. For example, the range “1.0 to 10.0” is intended to include all subranges between the described minimum value of 1.0 and the described maximum value of 10.0 (inclusive), i.e., a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit described herein is intended to include all smaller numerical limits contained therein, and any minimum numerical limit described herein is intended to include all larger numerical limits contained therein. Therefore, the applicant reserves the right to amend this specification (including the claims) to expressly describe any subranges contained within the scope expressly described herein.

[0035] Classifying two compared elements, features, etc., as “identical” can mean that they are “substantially identical.” Therefore, the phrase “substantially identical” can include cases with what is considered a low degree of deviation in the art (e.g., 5% or less). Furthermore, when a parameter is said to be uniform in a given region, this can mean uniform in terms of average value.

[0036] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0037] When any element is described as being "above (or below)" or "on (or below)" a component, it may mean that the element is positioned to contact the upper (or lower) surface of the component, or it may mean that another component can be inserted between the component and any element that is being positioned (or below) the component.

[0038] Furthermore, it will be understood that when an element is referred to as being "joined," "linked," or "connected" to another element, these elements may be directly "joined," "linked," or "connected" to each other, or there may be an intermediary element between them through which the one element can be "joined," "linked," or "connected" to the other element. Additionally, when a part (component) is referred to as being "electrically joined" to another part (component), the part (component) may be directly connected to the other part, or there may be an intermediary part (component) between them, such that the part (component) is indirectly connected to the other part.

[0039] Throughout this specification, when “A and / or B” is mentioned, unless otherwise specified, it means A, B, or A and B. That is, “and / or” includes any or all of the listed items. When “C to D” is mentioned, unless otherwise specified, it means C or greater and D or less.

[0040] Due to various factors originating from the manufacturing process of individual battery cells, capacity variations exist among the cells that make up a battery pack. Furthermore, with repeated charging and discharging of the cells, variations arise between their individual voltages. Therefore, during charging, some cells may be overcharged, or during discharging, some cells may be over-discharged. Consequently, due to overcharging or over-discharging of some cells, not only will the battery pack's capacity decrease, but its degradation will also progress rapidly, and its lifespan will be shortened.

[0041] To eliminate capacity and voltage deviations between individual battery cells, a cell balancing function is applied to the battery management system (BMS) of the battery pack. The BMS discharges the cells with relatively high capacity and voltage, so that the capacity and voltage of each cell are distributed within a set range.

[0042] Figure 1 This is a circuit diagram of a battery cell balancing device according to an embodiment of the present disclosure. Figures 2 to 4 This is an exemplary diagram illustrating the process of performing battery cell balancing in a battery cell balancing device according to an embodiment of the present disclosure. Figure 5 This is an exemplary diagram illustrating a cell voltage measurement error caused by an anomaly in the RC circuit of a cell balancing device according to an embodiment of the present disclosure, and Figure 6 and Figure 7 This is an exemplary diagram illustrating the error compensation operation of a battery cell balancing device according to an embodiment of the present disclosure.

[0043] First, refer to Figure 1 The battery cell balancing device according to the embodiment may include an RC circuit 100, a balancing circuit 200, and a processor 300. For example... Figure 1 As shown, the RC circuit 100 and the balancing circuit 200 can be provided in numbers corresponding to the number of battery cells connected in series, and the balancing control operation of the processor 300 described herein can be performed on each battery cell. Since the specific balancing control operation performed on each battery cell is the same, the description of the embodiment focuses on the process of controlling the balancing of a particular battery cell.

[0044] RC circuit 100 may correspond to a filter circuit connected between the battery cell and the balancing circuit 200 described herein to stably measure the cell voltage. RC circuit 100 may include a resistor R and a capacitor C when balancing the battery cells is performed (i.e., the balancing switch SW described herein). b (In the ON state), resistor R is connected in the path from which current is drawn from the battery cell, and capacitor C is connected in parallel to balancing circuit 200 at the node where resistor R and balancing circuit 200 are connected, and is charged by the current drawn from the battery cell. The processor 300 described herein can be operated to measure the voltage across capacitor C of RC circuit 100 as the individual cell voltage. The resistance value of resistor R and the capacitance of capacitor C can be designed to specific values ​​based on battery pack specifications and designer experimental results to prevent distortion of individual cell voltage measurements due to battery balancing operation of processor 300 described herein.

[0045] The balancing circuit 200 may include a balancing resistor Rb and a balancing switch SW. bBalance resistor Rb and balance switch SW b Set on the discharge path formed when balancing individual battery cells is performed. Balance switch SW b The on / off operation can be controlled by the processor 300, and the balance switch SW b This can be achieved using relays or field-effect transistors (FETs). Figures 1 to 3 An example is shown in which the balancing circuit 200 is separated from the processor 300 in the circuit, but embodiments in which the balancing circuit 200 is included (integrated) in the processor 300 are also possible.

[0046] The processor 300 is an entity that detects anomalies in the aforementioned RC circuit 100 and controls the balance of individual battery cells based on the detection results. It can be implemented as a central processing unit (CPU) or a system-on-a-chip (SoC). It can control multiple hardware or software components connected to the processor 300 by driving an operating system or application, and can perform various types of data processing and calculations. Specifically, in the illustrated embodiment, the processor 300 can correspond to the analog front-end integrated circuit (AFE IC) of a battery management system (BMS). The BMS monitors the state of the battery, such as the voltage, current, temperature, and state of charge (SOC) of individual battery cells, and controls the balance of the battery cells based on the monitoring results.

[0047] The balancing cycle of the battery cells via processor 300, based on capacitor C, is described below. For reference, Figures 2 to 4 Assume that no abnormality occurs in RC circuit 100.

[0048] Reference Figure 2 and Figure 4 When it is determined that the battery cells need to be balanced, the processor 300 turns on the balance switch SW. b Therefore, since current flows from capacitor C to the balancing circuit 200, capacitor C is discharged. When the current flows from the balancing switch SW... b The predefined balancing time t has elapsed since the connection was established. b At that time, processor 300 disconnects the balance switch SW b To achieve balance. The above operations are represented as operations. .

[0049] Reference Figure 3 and Figure 4 When the balance switch SW b When disconnected, capacitor C is charged by the current drawn from the battery cell. When the balance switch SW is turned off... b The time t elapsed from the point of disconnection to the time constant τ=RC of the RC circuit is equal to 100. d(Or more precisely, at 5τ, for convenience, 5τ represents a time constant in this embodiment), the RC circuit 100 enters a steady state, and the processor 300 operates to measure the voltage of capacitor C in the steady state as the individual cell voltage of the battery cell. The above operation is referred to as operation... .

[0050] In operation In this configuration, processor 300 is set to operate from the balance switch SW. b Predefined delay time t from the time of disconnection d The individual cell voltage was then measured using RC circuit 100. The aforementioned delay time t... d This can be the time corresponding to the time constant of the RC circuit 100 when no abnormality occurs. That is, the processor 300 can measure the voltage of capacitor C as the voltage of a single battery cell in the steady state of the RC circuit 100, which is the voltage at the balance switch SW. b It is formed when the capacitor C is charged by the current drawn from the battery cell when the battery is disconnected.

[0051] Simultaneously, when a defect occurs in the connection between resistor R and capacitor C, or when the resistance or capacitance increases due to damage to resistor R or capacitor C (in this embodiment, this corresponds to an abnormality occurring in RC circuit 100), the time constant of RC circuit 100 increases, therefore, the time constant from the balance switch SW increases. b From the point of disconnection, the time required for the RC circuit 100 to reach a steady state also increases (see...). Figure 5 (B) As described above, the processor 300 operates to switch from the balance switch SW. b The time of disconnection is followed by a delay t. d (That is, the time point after which the battery cell voltage is measured when no abnormality occurs in the RC circuit 100) the time constant of the RC circuit 100 is in a state where no abnormality occurs in the RC circuit 100. Therefore, as Figure 5 As shown, when no abnormality occurs in RC circuit 100 (see...) Figure 5 In the above, 'A') is processed by processor 300 based on the delay time t mentioned above. d The unit voltage measured at a specific time point is compared with the voltage measured when an anomaly occurs in RC circuit 100 (see...). Figure 5 The error V between the individual unit voltages measured by the processor 300 based on the time point corresponding to the aforementioned delay time td (B) is observed. ERR When the battery pack and peripheral circuitry are controlled based on the individual cell voltages that reflect this error, additional battery pack failures may occur.

[0052] The embodiment proposes a cell balancing mechanism to detect cell voltage measurement errors (i.e.,Figure 5 The "V" in ERR This extends the battery pack's lifespan and allows for maximum use of the balancing function within a range that can compensate for individual cell voltage measurement errors.

[0053] Specifically, after the battery cells are balanced, the processor 300 can measure the individual cell voltage via the RC circuit 100, and when an anomaly is determined to have occurred in the RC circuit 100 based on the measured individual cell voltage, the processor 300 can control the balance switch SW. b The switching time is adjusted to compensate for the individual voltage measurement error caused by the abnormality of RC circuit 100.

[0054] The cell voltage measurement error is defined as the error between the first cell voltage measured before performing cell balancing and the voltage measured from the balance switch SW. b The difference between the second cell voltages measured after a delay from the point when the battery cells are balanced upon disconnection. The first cell voltage measured before balancing corresponds to the steady state of RC circuit 100 (this steady state is the balance switch SW). b The voltage of capacitor C in the disconnected state is used as a reference value compared with the voltage of the second single cell to determine whether the RC circuit 100 is abnormal.

[0055] Since the single-unit voltage measurement error as defined above is greater than or equal to a predefined threshold, corresponding to the following... Figure 5 As shown, due to an anomaly in the RC circuit 100, the time constant increases. Therefore, the processor 300 can subsequently determine that the RC circuit 100 has malfunctioned and compensate for the individual cell voltage measurement error. The aforementioned threshold is a value compared to the difference between the first and second individual cell voltages to determine whether an anomaly has occurred in the RC circuit 100, and can be designed as a specific value based on the designer's experimental results.

[0056] As described herein, processor 300 is configured to turn on balance switch SW when performing battery cell balancing, provided that no abnormality occurs in RC circuit 100. b The predefined balancing time is reached. On the other hand, when an abnormality occurs in the RC circuit 100, the processor 300 can compensate for the individual voltage measurement error by shortening the balancing time.

[0057] Specifically, when the individual cell voltage measurement error is compensated, the processor 300 can adjust the balance switch SW. b The disconnection time is predefined by the calibration time t. c To shorten the balancing time.

[0058] Reference Figure 6 With the balance switch SWb The earlier the disconnection time, the more the individual cell voltage shifts to the left. This means that, from the balancing switch SW... b The second individual cell voltage measured at a time point after a delay from the point of disconnection is close to the first individual cell voltage V1 corresponding to the voltage of capacitor C in the steady state of RC circuit 100. Therefore, the individual cell voltage measurement error V ERR Decrease.

[0059] When the balance switch SW is turned on b Disconnection time point advance calibration time t c When the operation is defined as error compensation operation, the processor 300 can repeatedly execute the error compensation operation whenever the battery cell balancing is performed, until the cell voltage measurement error V is reached. ERR Less than threshold V TH . Figure 6 This shows the single-cell voltage measurement error V when three error compensation operations are performed. ERR Less than threshold V TH Example. When the unit voltage measurement error V ERR Less than threshold V TH At that time, the processor 300 can operate according to the final shortened balancing time when performing balancing after the corresponding time point in time, so as to control the balancing of the corresponding battery cell.

[0060] like Figure 7 As shown, when the error compensation operation is repeatedly performed but the individual cell voltage measurement error V ERR Maintain at threshold V TH Above or equal to the threshold V TH If the shortened balancing time (i.e., the available time to perform balancing) is less than or equal to the calibration time, and it is impossible to further shorten the balancing time, the processor 300 may stop balancing the battery cells after the current time point and notify the user of this situation through an interface device (not shown) for interacting with the user.

[0061] The process of periodically determining anomalies in the RC circuit 100 based on the individual cell voltages measured by the RC circuit 100 according to a predefined cycle and performing error compensation operations based on the determination results can be performed. Therefore, the phenomenon that individual cell voltage measurement errors continuously increase over a long period as the balance of the individual cells continues can be prevented.

[0062] In the above text, the entity that determines anomalies in the RC circuit 100 based on the cell voltage of the battery cell measured by the RC circuit 100 and performs error compensation operations according to the determination result is described as corresponding to the processor 300 (i.e., AFE IC), such as Figure 8As shown, this operation of the processor 300 can also be functionally separated and performed by the BMS's AFE IC 310 and microcontroller unit (MCU) 320.

[0063] Specifically, the AFE IC 310 can measure the first cell voltage of a battery cell through the RC circuit 100, and transmit the first cell voltage to the MCU 320 before performing cell balancing. Under the control of the MCU 320, cell balancing is then performed. After cell balancing is completed, the AFE IC 310 can measure the second cell voltage of a battery cell through the RC circuit 100 and transmit the second cell voltage to the MCU 320.

[0064] The MCU 320 determines whether an anomaly has occurred in the RC circuit 100 based on the first and second individual cell voltages received from the AFE IC 310, and when an anomaly is determined to have occurred in the RC circuit, it can send a control signal SW to the AFE IC 310 to control the balance switch. b The control signal for the switching time.

[0065] Subsequently, the AFE IC 310 can control the balance switch SW based on the control signals received from the MCU 320. b The switching time is adjusted to compensate for individual voltage measurement errors caused by abnormalities in the RC circuit 100.

[0066] In the above embodiment, the RC circuit 100, the balancing circuit 200, the AFE IC 310, and the MCU 320 constitute the BMS.

[0067] Figure 9 This is a flowchart of a battery cell balancing method according to an embodiment of the present disclosure. (Refer to...) Figure 9 The battery cell balancing method described in the embodiments will omit specific descriptions of configurations that are repeated above, and will focus on describing the time series configuration.

[0068] First, before performing battery cell balancing, the processor 300 measures the cell voltage (i.e., the first cell voltage) via the RC circuit 100 (S100). The cell voltage measured in operation S100 corresponds to the voltage when capacitor C is switched on the balance switch SW. b The steady-state voltage formed when the battery is charged by the current drawn from the individual cells when disconnected.

[0069] Subsequently, the processor 300 performs battery cell balancing via the balancing circuit 200 (S200). Operation S200 corresponds to the operation prior to determining whether there is an anomaly in the RC circuit 100; therefore, in operation S200, the processor 300 activates the balancing switch SW.b The battery cells are balanced when a predefined balancing time is reached.

[0070] Subsequently, after balancing the battery cells in operation S200, the processor 300 measures the individual cell voltage (i.e., the second individual cell voltage) via the RC circuit 100 (S300). The individual cell voltage measured in operation S300 corresponds to the voltage measured from the balancing switch SW. b The voltage measured by RC circuit 100 after a predefined delay from the point of disconnection.

[0071] Subsequently, the processor 300 determines whether an anomaly has occurred in the RC circuit 100 based on the individual cell voltages (i.e., the first individual cell voltage and the second individual cell voltage) measured in operations S100 and S300, respectively (S400). In operation S400, when the difference between the first individual cell voltage and the second individual cell voltage (i.e., the individual cell voltage measurement error) is greater than or equal to a predefined threshold, the processor 300 determines that an anomaly has occurred in the RC circuit 100.

[0072] When an abnormality is determined to have occurred in the RC circuit 100 during operation S400, the processor 300 controls the balance switch SW during the next balancing operation. b The switching time is adjusted to compensate for the individual voltage measurement error caused by the abnormality in the RC circuit 100 (S500).

[0073] In operation S500, processor 300 compensates for individual cell voltage measurement errors by shortening the predefined balancing time (i.e., the balancing time applied to operation S200). In other words, the balancing time applied to operation S500 has a shorter duration than the balancing time applied to operation S200. In this case, processor 300 compensates for the individual cell voltage measurement error by shortening the predefined balancing time (i.e., the balancing time applied to operation S200). b The disconnection time is predefined and the calibration time is used to shorten the balancing time.

[0074] When the balance switch SW is turned on b When the operation of calibrating the disconnection time in advance is defined as an error compensation operation, in operation S500, the processor 300 repeatedly performs the error compensation operation whenever the battery cell is balanced, until the cell voltage measurement error is less than a predefined threshold within the range that may further shorten the balancing time.

[0075] When it is determined through operation S500 that the single cell voltage measurement error is less than the threshold (S600), the processor 300 controls the balance of the corresponding battery cell according to the final shortened balance time when performing balancing after the corresponding time point (S700).

[0076] Even if the error compensation operation is repeatedly performed by operating S500, the single cell voltage measurement error remains above or equal to the threshold (S600), and when it is determined that the balance time shortened so far is less than or equal to the calibration time, and therefore it is impossible to further shorten the balance time (S800), the processor 300 may stop the balancing of the corresponding battery cell after the current time point and notify the user of this situation through an interface device for interacting with the user (S900).

[0077] As described herein, according to this disclosure, when an anomaly is determined to have occurred in the RC circuit based on the individual cell voltage, the battery pack's lifespan can be extended by preventing secondary mismeasurements of the individual cell voltage caused by the anomaly in the RC circuit and by allowing the balancing function to be used to the maximum extent possible within the range that can compensate for individual cell voltage measurement errors, since the switching time of the balancing switch is controlled to compensate for the individual cell voltage measurement error in the RC circuit.

[0078] The embodiments described herein can be implemented as, for example, methods or processes, apparatus, software programs, data streams, or signals. Although discussed in the context of a single implementation type (e.g., as a method), the features discussed herein can also be implemented in other forms (e.g., apparatus or program). Apparatus can be implemented by suitable hardware, software (e.g., instructions encoded on at least one non-transient computer-readable storage medium), firmware, etc. Methods can be implemented on apparatuses (such as processors, which generally refer to processing apparatuses including computers, microprocessors, integrated circuits, programmable logic devices, etc.). Processors include communication devices, such as computers, cellular phones, personal digital assistants (PDAs), and other devices that facilitate information communication between the device and the end user.

[0079] According to this disclosure, when an abnormality is determined to have occurred in the RC circuit based on the individual cell voltage, the switching time of the balance switch is controlled to compensate for the individual cell voltage measurement error caused by the abnormality in the RC circuit. Furthermore, by preventing secondary mismeasurement of individual cell voltage caused by the abnormality in the RC circuit and allowing the balancing function to be used to the maximum extent within the range that can compensate for the individual cell voltage measurement error, the service life of the battery pack can be extended.

[0080] However, the effects that can be achieved by the present invention are not limited to those described above, and those skilled in the art can clearly understand other effects not described from the detailed description.

[0081] While this disclosure has been described with reference to embodiments and accompanying drawings illustrating various aspects thereof, this disclosure is not limited thereto. Various modifications and variations can be made by those skilled in the art within the technical spirit of this disclosure and the claims and their equivalents.

Claims

1. A battery cell balancing device, the battery cell balancing device comprising: A balancing circuit, including a balancing switch, wherein the balancing switch is disposed on the discharge path formed when balancing individual battery cells is performed; An RC circuit is connected between the battery cell and the balancing circuit to measure the cell voltage. as well as After balancing the battery cells, the processor measures the cell voltage of the battery cells via the RC circuit, and determines the switching time of the balancing switch when an anomaly has occurred in the RC circuit based on the measured cell voltage, in order to compensate for the cell voltage measurement error caused by the anomaly in the RC circuit.

2. The battery cell balancing device according to claim 1, wherein, The processor is configured to measure the cell voltage via the RC circuit after a predefined delay time from the point when the balancing switch is turned off, when measuring the cell voltage after the cell has been balanced.

3. The battery cell balancing device according to claim 2, wherein, The delay time is predefined based on the time constant of the RC circuit when no abnormality occurs in the RC circuit.

4. The battery cell balancing device according to claim 2, wherein, The cell voltage measurement error is defined as the difference between a first cell voltage measured before the balancing of the cell is performed and a second cell voltage measured after the delay time from the point when the balancing switch is turned off when the cell is balanced.

5. The battery cell balancing device according to claim 4, wherein: The RC circuit includes: a resistor connected in the path through which the current drawn from the battery cell passes; and a capacitor connected in parallel to the balancing circuit at the node where the resistor and the balancing circuit are connected, and charged by the current drawn from the battery cell; and The first cell voltage is the voltage in a steady state formed when the capacitor is charged by the current drawn from the cell.

6. The battery cell balancing device according to claim 4, wherein, When the individual cell voltage measurement error is greater than or equal to a predefined threshold, the processor determines that an anomaly has occurred in the RC circuit.

7. The battery cell balancing device according to claim 1, wherein, The processor is configured to: when no abnormality occurs in the RC circuit, turn on the balancing switch for a predefined balancing time during the balancing of the battery cells; and shorten the balancing time when compensating for the voltage measurement error of the battery cells.

8. The battery cell balancing device according to claim 7, wherein, When compensating for the individual unit voltage measurement error, the processor shortens the balancing time by pre-defining the calibration time before the balancing switch is turned off.

9. The battery cell balancing device according to claim 8, wherein, When the operation of advancing the disconnection time of the balance switch to the predefined calibration time is defined as an error compensation operation, the processor repeats the error compensation operation whenever the balancing of the battery cell is performed, until the voltage measurement error of the cell is less than the predefined threshold.

10. The battery cell balancing device according to claim 9, wherein, When the shortened balancing time according to the repeated error compensation operation is less than or equal to the predefined calibration time, and the cell voltage measurement error remains above or equal to the predefined threshold, the processor stops the balancing of the cell after the current time point.

11. A method for balancing individual battery cells, the method comprising the following steps: The processor performs balancing of individual battery cells via a balancing circuit, wherein the balancing circuit includes a balancing switch disposed on the discharge path formed when the balancing of the individual battery cells is performed; After the balancing of the battery cells is completed, the processor measures the individual cell voltage of the battery cells through an RC circuit, wherein the RC circuit is connected between the battery cells and the balancing circuit to measure the individual cell voltage of the battery cells. The processor determines whether an anomaly has occurred in the RC circuit based on the measured unit voltage; and When an anomaly is detected in the RC circuit, the processor controls the switching time of the balance switch to compensate for the individual voltage measurement error caused by the anomaly in the RC circuit.

12. The battery cell balancing method according to claim 11, wherein, In the measurement step, the processor measures the individual cell voltage via the RC circuit after a predefined delay time from the point when the balance switch is turned off.

13. The battery cell balancing method according to claim 12, wherein: The RC circuit includes: a resistor connected in the path from which current is drawn from the battery cell; and a capacitor connected in parallel to the balancing circuit at the node where the resistor and the balancing circuit are connected, and charged by the current drawn from the battery cell; and The battery cell balancing method further includes: measuring a first cell voltage of the battery cell by the processor before the execution step, wherein the first cell voltage is the voltage in a steady state formed when the capacitor is charged by the current drawn from the battery cell when the balancing switch is off.

14. The battery cell balancing method according to claim 13, wherein, The cell voltage measurement error is defined as the difference between the first cell voltage and the second cell voltage measured after the delay time from the point when the balance switch is turned off, when the cell balance is completed.

15. The battery cell balancing method according to claim 14, wherein, In the determination step, when the individual cell voltage measurement error is greater than or equal to a predefined threshold, the processor determines that an anomaly has occurred in the RC circuit.

16. The battery cell balancing method according to claim 11, wherein: The processor is configured to: when no abnormality occurs in the RC circuit, during the balancing of the battery cells, activate the balancing switch for a predefined balancing time; and In the compensation step, the processor shortens the predefined balancing time.

17. The battery cell balancing method according to claim 16, wherein, In the compensation step, the processor shortens the predefined balancing time by advancing the disconnection time of the balancing switch by a predefined calibration time.

18. The battery cell balancing method according to claim 17, wherein, When the operation of advancing the disconnection time of the balance switch to the predefined calibration time is defined as an error compensation operation, in the compensation step, whenever the balancing of the battery cell is performed, the processor repeatedly performs the error compensation operation until the cell voltage measurement error is less than a predefined threshold.

19. The battery cell balancing method according to claim 18, further comprising: When the shortened balancing time according to the repeatedly performed error compensation operation is less than or equal to the predefined calibration time, and the cell voltage measurement error remains above or equal to the predefined threshold, the processor stops the balancing of the cell after the current time point.

20. A battery management system, the battery management system comprising: A balancing circuit, including a balancing switch, wherein the balancing switch is disposed on the discharge path formed when balancing individual battery cells is performed; An RC circuit is connected between the battery cell and the balancing circuit to measure the cell voltage. An analog front-end integrated circuit is configured to measure the cell voltage of the battery cell via the RC circuit after the balancing of the battery cell is completed; as well as The microcontroller unit receives the individual cell voltage measured by the analog front-end integrated circuit and determines whether an anomaly has occurred in the RC circuit. When an anomaly is determined to have occurred in the RC circuit, it sends a control signal to the analog front-end integrated circuit to control the switching time of the balance switch. The analog front-end integrated circuit controls the switching time of the balance switch based on the control signal received from the microcontroller unit to compensate for the individual voltage measurement error caused by the abnormality in the RC circuit.

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