Battery management system, battery pack, electric vehicle, and battery management method

Abstract

To provide a technology for detecting an internal short circuit failure of a battery.SOLUTION: A battery management system according to the present disclosure includes a battery monitor configured to acquire a voltage of each of a plurality of batteries, and a processor configured to compensate for a no-loadvoltage value of each battery using a balancing capacity of each battery according to a previously performed balancing process in a state in which a balancing process for the plurality of batteries is not performed, determine a voltage difference between the compensated no-loadvoltage value of each battery and a reference voltage value, and detect whether each battery is abnormal based on a change amount of the voltage difference of each battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for detecting an internal short circuit fault in a battery.

[0002] This application claims priority based on Korean Patent Application No. 10-2021-0098141, filed on July 26, 2021, and the entire contents disclosed in the specification and drawings of that application are incorporated herein by reference. [Background technology]

[0003] Recently, as demand for portable electronic products such as notebook PCs, video cameras, and mobile phones has skyrocketed, and development of electric vehicles, energy storage batteries, robots, and satellites has gained momentum, research into high-performance batteries that can be repeatedly charged and discharged is actively underway.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are attracting attention due to their advantages of having almost no memory effect compared to nickel-based batteries, being freely chargeable and dischargeable, having a very low self-discharge rate, and having a high energy density.

[0005] To meet the high voltage and large capacity requirements of applications such as electric vehicles, battery systems (e.g., battery packs) including at least one battery group (i.e., a series connection of a plurality of batteries) have become widespread.

[0006] In such a battery system, failure of several batteries is likely to adversely affect the overall performance and safety of the battery system, so it is important to properly detect failures of individual batteries when operating the battery system.

[0007] Batteries can have different characteristics due to internal and external factors during the manufacturing process and / or use. These differences in characteristics between batteries can lead to voltage imbalances. Balancers are widely used to balance (e.g., discharge) each battery to eliminate voltage imbalances between batteries.

[0008] Among the various types of battery failures, internal short circuit failure is the main failure that directly or indirectly affects fires. An internal short circuit failure refers to a state in which a leakage current path is created due to a side reaction within the battery and / or the penetration of foreign matter into the battery. Conventionally, batteries with internal short circuit failures were detected by using the voltage unevenness of multiple batteries.

[0009] However, when the balancing process is performed, the voltage unevenness among the multiple batteries, which is important information for detecting an internal short circuit, is eliminated. In other words, when detecting a battery with an internal short circuit from multiple batteries, the balancing process that was previously performed acts as an interference factor. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a battery management system, a battery pack, an electric vehicle, and a battery management method that can accurately detect a battery that has an internal short circuit fault among multiple batteries even when the voltage unevenness among multiple batteries has been eliminated by balancing processing.

[0011] Other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings, in which: FIG. 1 is a block diagram of a semiconductor device according to an embodiment of the present invention; FIG. 2 is a block diagram of a semiconductor device according to an embodiment of the present invention; [Means for solving the problem]

[0012] According to one aspect of the present invention, a battery management system includes a battery monitor that acquires the voltage of each of a plurality of batteries; and a processor that, when a balancing process for the plurality of batteries has not been performed, compensates for a no-load voltage value of each of the batteries using a balancing capacity of each battery obtained by a previous balancing process, determines a voltage difference between the compensated no-load voltage value of each of the batteries and a reference voltage value, and detects whether or not each of the batteries has an abnormality based on a change in the voltage difference of each of the batteries.

[0013] The processor may be configured to increase a fault count of each battery by 1 if the change in the voltage difference of each battery is equal to or greater than a critical value, and to detect each battery as having an internal short circuit fault if the fault count of each battery is equal to or greater than a predetermined value.

[0014] The reference voltage value may be an average or median of the compensated no-load voltage values ​​of at least two batteries among the plurality of batteries.

[0015] The processor may compensate for the no-load voltage value using a balancing capacitance obtained by a balancing process performed during a reference time, which may be longer than a time period during which the balancing process is performed.

[0016] The processor may be configured to determine the balancing capacity of each battery by accumulating the discharge capacity of each battery due to each balancing process performed within a reference time period.

[0017] The processor may be configured to apply a capacity estimation function to first balancing data associated with each balancing process to determine the discharge capacity of each battery due to the balancing process, the first balancing data including a no-load voltage value of each battery at the start of the balancing process and a duration of the balancing process.

[0018] The processor may be configured to apply a SOC-OCV map to second balancing data for each balancing process to determine the discharge capacity of each battery for each balancing process. The second balancing data may include a no-load voltage value for each battery at the start of the balancing process and a no-load voltage value for each battery at the end of the balancing process.

[0019] The processor may be configured to apply an SOC-OCV map to the no-load voltage value of each battery to determine an estimated SOC of each battery, compensate the estimated SOC of each battery by adjusting the estimated SOC of each battery by an SOC change amount corresponding to the balancing capacity, and apply the SOC-OCV map to the compensated estimated SOC of each battery to determine the compensated no-load voltage value.

[0020] A battery pack according to another aspect of the present invention includes the battery management system.

[0021] According to yet another aspect of the present invention, an electric vehicle includes the battery pack.

[0022] According to yet another aspect of the present invention, a battery management method includes the steps of: acquiring a no-load voltage value of each of a plurality of batteries; compensating the no-load voltage value of each of the batteries using a balancing capacity of each battery obtained by a previous balancing process when no balancing process has been performed on the plurality of batteries; determining a voltage difference between the compensated no-load voltage value of each of the batteries and a reference voltage value; and detecting whether or not there is an abnormality in each of the batteries based on an amount of change in the voltage difference of each of the batteries.

[0023] The step of detecting whether or not each battery has an abnormality may include the steps of: increasing a fault count of each battery by 1 when the amount of change in the voltage difference of each battery is equal to or greater than a critical value; and detecting each battery as having an internal short circuit fault when the fault count of each battery is equal to or greater than a predetermined value.

[0024] The reference voltage value is an average or median of the compensated no-load voltage values ​​of at least two batteries among the plurality of batteries.

[0025] The step of compensating the no-load voltage value of each battery may include the steps of: determining an estimated SOC value of each battery by applying an SOC-OCV map to the no-load voltage value of each battery; compensating the estimated SOC value of each battery by adding an SOC change amount corresponding to the balancing capacity to the estimated SOC value of each battery; and determining the compensated no-load voltage value by applying the SOC-OCV map to the compensated estimated SOC value of each battery. [Effects of the Invention]

[0026] According to at least one embodiment of the present invention, even when the voltage unevenness among the plurality of batteries is eliminated by the balancing process, it is possible to accurately detect a battery with an internal short circuit fault among the plurality of batteries.

[0027] The effects of the present invention are not limited to the effects described above, and other effects of the present invention not mentioned above will be clearly understood by those skilled in the art from the description of the claims.

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention, so the present invention should not be interpreted as being limited to the matters described in the drawings. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a diagram showing the configuration of an electric vehicle according to the present invention; [Figure 2] FIG. 2 is a reference diagram for explaining an exemplary equivalent circuit of a battery. [Figure 3] FIG. 2 is a reference diagram for explaining the principle of detecting an internal short circuit fault in a battery. [Figure 4] FIG. 2 is a reference diagram for explaining the principle of detecting an internal short circuit fault in a battery. [Figure 5] FIG. 2 is a reference diagram for explaining the principle of detecting an internal short circuit fault in a battery. [Figure 6] FIG. 2 is a reference diagram for explaining the principle of detecting an internal short circuit fault in a battery. [Figure 7] 1 is a flowchart illustrating a battery management method according to a first embodiment of the present invention. [Figure 8] 1 is a flowchart illustrating a battery management method according to a first embodiment of the present invention. [Figure 9] 5 is a flowchart illustrating a battery management method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best explain the invention.

[0031] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0032] Terms including ordinal numbers such as "first," "second," etc. are used to distinguish one of various components from the rest, and do not limit the components.

[0033] Furthermore, throughout the specification, when a part "includes" a certain element, this does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified. Furthermore, terms such as "controller" in the specification refer to a unit that processes at least one function or operation, and this may be embodied by hardware, software, or a combination of hardware and software.

[0034] Furthermore, throughout this specification, when a part is said to be "coupled" to another part, this includes not only "directly coupled" but also "indirectly coupled" via another element in between.

[0035] FIG. 1 is a diagram showing the configuration of an electric vehicle according to the present invention.

[0036] 1, an electric vehicle 1 includes a vehicle controller 2, a battery pack 10, and an electric load 30. Charging and discharging terminals P+ and P− of the battery pack 10 may be electrically coupled to a charger 40 via a charging cable or the like. The charger 40 may be included in the electric vehicle 1 or may be provided in a charging station external to the electric vehicle 1.

[0037] The vehicle controller 2 (e.g., ECU: Electronic Control Unit) is configured to transmit a key-on signal to the battery management system 100 in response to a start button (not shown) provided on the electric vehicle 1 being switched to an on position by a user. The vehicle controller 2 is configured to transmit a key-off signal to the battery management system 100 in response to a start button being switched to an off position by a user. The charger 40 can communicate with the vehicle controller 2 to supply charging power (e.g., constant current, constant voltage, constant power) via the charging and discharging terminals P+, P- of the battery pack 10.

[0038] The battery pack 10 includes a battery group 11 , a relay 20 and a battery management system 100 .

[0039] The battery group 11 includes a plurality of batteries B1 to B N (N is a natural number of 2 or more) in series connection. That is, in the battery group 11, a plurality of batteries B1 to B N are connected in series to each other. N The battery may include one unit cell or two or more unit cells connected in series, parallel, or series-parallel, which are manufactured to have the same electrochemical specifications. A unit cell is the smallest unit of a storage element that can be charged and discharged independently. For example, the type of unit cell is not particularly limited as long as it can be repeatedly charged and discharged, such as a lithium-ion cell.

[0040] In the following, multiple batteries B1 to B N When explaining the contents common to all of the above, the letter "B" will be used to refer to the battery.

[0041] The relay 20 is electrically connected in series to the battery group 11 through a power path connecting the battery group 11 and the electrical load 30. In FIG. 1 , the relay 20 is shown connected between the positive terminal of the battery group 11 and the charge / discharge terminal P+. The relay 20 is controlled to be turned on and off in response to a switching signal from the battery management system 100 and / or the vehicle controller 2. The relay 20 may be a mechanical switch that is turned on and off by the magnetic force of a coil, or may be a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0042] The electric load 30 includes an inverter 31 and an electric motor 32. The inverter 31 is provided to convert direct current from the batteries 11 included in the battery pack 10 into alternating current in response to a command from the battery management system 100 or the vehicle controller 2. The electric motor 32 is driven using the alternating current power from the inverter 31. The electric motor 32 may be, for example, a three-phase alternating current motor.

[0043] The state in which the relay 20 is turned on and the battery B is being charged or discharged can be called a load state (cycle state).

[0044] When the relay 20 is switched from on to off, the battery B enters a no-load state (resting state, calendar state), and the battery voltage of the battery B in the no-load state may be referred to as the no-load voltage. The no-load voltage is a general term for the relaxation voltage and the open circuit voltage (OCV). Specifically, when the battery B is switched from a loaded state to a no-load state, the no-load voltage of the battery B changes as the polarization generated in the battery B naturally dissipates. The OCV indicates the no-load voltage when the rate of change in the voltage of the battery B becomes less than a certain value after the battery B is maintained in the no-load state for a predetermined time (e.g., 2 hours) or more. In other words, the OCV is the no-load voltage when the polarization of the battery B is negligibly small. The relaxation voltage indicates the no-load voltage while the polarization is naturally dissipating.

[0045] The battery management system 100 includes a battery monitor 110, a balancer 130, and a control circuit 140. The battery management system 100 may further include a communication circuit 150. Hereinafter, the battery management system 100 may include the battery monitor 110, the control circuit 140, and the communication circuit 150.

[0046] The battery monitor 110 includes a voltage detection circuit 112. The battery monitor 110 may further include a current detector 114.

[0047] The voltage detection circuit 112 detects the voltages of the batteries B1 to B2 included in the battery group 11. N and is configured to detect the voltage across battery B (sometimes referred to as the battery voltage) and generate a voltage signal indicative of the detected battery voltage.

[0048] The current detector 114 is connected in series to the battery group 11 through a current path between the battery group 11 and the inverter 30. The current detector 114 may be implemented by one or a combination of two or more known current detection elements such as a shunt resistor, a Hall effect element, etc. N are connected in series, so multiple batteries B1 to B N A common charge / discharge current flows through

[0049] 1 shows that a shunt resistor is used as the current detector 114. In this case, the voltage detection circuit 112 can output a current signal indicating the direction and magnitude of the charge / discharge current to the control circuit 140 based on the voltage applied across the shunt resistor. Of course, the current detector 114 can also directly generate a current signal indicating the charge / discharge current flowing through the battery group 11 and output it to the control circuit 140.

[0050] The balancer 130 balances the batteries B1 to B2 in response to a balancing command from the control circuit 140. N The balancing execution command is configured to execute a balancing process for battery B, which needs balancing, among the plurality of batteries B1 to B2. Hereinafter, the battery B, which is determined to need balancing, is referred to as the "target battery." N The target time may include a target time for the target battery B. The target time means the duration of the balancing process required for the target battery B.

[0051] In FIG. 1, as an example of the balancer 130, the balancer 130 is configured with a plurality of balancing circuits D1 to D N The figure shows a case where multiple balancing circuits D1 to D N Multiple batteries B1 to B N In the following, a plurality of balancing circuits D1 to D N When explaining the contents common to all of the above, the letter "D" will be assigned to the battery.

[0052] Balancing circuit D is a series circuit of discharge resistor 131 and discharge switch 132. Discharge switch 132 is turned on in response to a balancing execution command. While discharge switch 132 is turned on, battery B is discharged by discharge resistor 131. Discharge switch 132 may be a semiconductor switch such as a MOSFET.

[0053] The control circuit 140 may be operably coupled to the relay 20, the battery monitor 110, the balancer 130, and the communication circuit 150. When two components are operably coupled, it means that the two components are directly or indirectly connected to each other so that signals can be sent and received unidirectionally or bidirectionally.

[0054] The control circuit 140 may be referred to as a "battery controller" and may be implemented in hardware using at least one of an ASIC (application specific integrated circuit), a DSP (digital signal processor), a DSPD (digital signal processing device), a PLD (programmable logic device), an FPGA (field programmable gate array), a microprocessor, or other electrical unit for performing a function.

[0055] The control circuit 140 may collect voltage signals and / or current signals from the battery monitor 110. In one example, the control circuit 140 may use an internal ADC (Analog to Digital Converter) to convert the analog signals collected from the battery monitor 110 into digital values ​​and record them. Alternatively, the battery monitor 110 may convert the analog signals into digital values ​​on its own and transmit the results to the control circuit 140.

[0056] The memory 141 may include at least one type of storage medium, such as a flash memory type, a hard disk type, a solid state disk (SSD) type, a silicon disk drive (SDD) type, a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable read-only memory (PROM). The memory unit 141 may store data and programs required for calculations performed by the control circuit 140. The memory unit 141 may store data indicating the results of calculations performed by the control circuit 140. The memory 141 may store predefined functions, logic, and algorithms to be used for detecting an internal short circuit fault in the battery B. The memory 141 may be integrated into the control unit 140.

[0057] The control circuit 140 can turn on the relay 20 in response to a key-on signal from the vehicle controller 2. The control circuit 140 can turn off the relay 20 in response to a key-off signal from the vehicle controller 2. The key-on signal is a signal requesting switching from an unloaded state to a loaded state. The key-off signal is a signal requesting switching from a loaded state to an unloaded state. Alternatively, the on / off control of the relay 20 can be handled by the vehicle controller 2 instead of the control circuit 140.

[0058] The control circuit 140 is configured to control the balancer 130 based on the voltage of the battery B detected by the battery monitor 110 .

[0059] The control circuit 140 controls a plurality of batteries B1 to B N The voltage of each of the batteries B1 to B N The maximum voltage and the minimum voltage of the plurality of batteries B1 to B2 can be identified. N The minimum voltage is the maximum voltage of the batteries B1 to B2. N This refers to the smallest voltage among the above.

[0060] The communication circuit 150 is configured to support wired or wireless communication between the control circuit 140 and the vehicle controller 2. The wired communication may be, for example, CAN (controller area network) communication, and the wireless communication may be, for example, ZigBee (registered trademark) or Bluetooth (registered trademark) communication. Of course, the type of communication protocol is not particularly limited as long as it supports wired or wireless communication between the control circuit 140 and the vehicle controller 2. The communication circuit 150 may include an output device (for example, a display, a speaker) that provides information received from the control circuit 140 and / or the vehicle controller 2 in a form that can be recognized by a user (driver).

[0061] The operation performed by the control circuit 140 to detect a battery with an internal short circuit fault will now be described in detail.

[0062] The control circuit 140 determines the voltage value of the no-load voltage of the battery B.

[0063] When battery B is in an unloaded state, control circuit 140 may determine the unloaded voltage value of battery B to be the same as the voltage value of battery B detected by battery monitor 110 .

[0064] When Battery B is in a loaded state, the control circuit 140 may use a battery state estimation algorithm to determine (estimate) a voltage value of the no-load voltage of Battery B based on the battery voltage of Battery B detected by the battery monitor 110 and the charge / discharge current of Battery B detected by the current detector 114. In one example, the no-load voltage of Battery B may be estimated by subtracting a voltage corresponding to the product of the charge / discharge current of Battery B and the internal resistance of Battery B from the battery voltage of Battery B detected by the battery monitor 110, according to Ohm's law.

[0065] Alternatively, the control circuit 140 may determine an estimated value of the state of charge (SOC) of battery B using a predetermined battery state estimation algorithm, regardless of whether battery B is in an unloaded state or a loaded state, and then obtain an OCV value related to the estimated value of SOC of battery B from a predetermined SOC-OCV map (see FIG. 5). A known algorithm (for example, a Kalman filter) may be used as the battery state estimation algorithm.

[0066] The control circuit 140 controls a plurality of batteries B1 to B N When the battery group 11 is switched from a loaded state to an unloaded state, the control circuit 140 determines the target battery B from among the plurality of batteries B1 to B2. N It may be determined whether or not balancing is required for at least one battery B among the battery group 11. The determination of the presence or absence of the target battery B may be performed when the battery group 11 is switched from a loaded state to an unloaded state, i.e., from the start of the unloaded state to the duration of the unloaded state.

[0067] In one example, the control circuit 140 controls a plurality of batteries B1 to B2 having no-load voltages. N In another example, the control circuit 140 may set the battery B having the SOC estimated value higher than the minimum no-load voltage of the plurality of batteries B1 to B2 by a reference value or more as the target battery. NBattery B, which has a minimum SOC higher than the reference value by more than a certain amount, can be set as the target battery.

[0068] The control circuit 140 controls the target battery (e.g., B i ) and a reference battery (e.g., B j The target capacity of the target battery B can be determined based on the capacity corresponding to the voltage difference (or SOC difference) between the reference battery and the target battery B. N The target capacity refers to the battery corresponding to the minimum no-load voltage (or minimum SOC) among the battery B. The control circuit 140 may determine the target time for the target battery B using a predetermined map that correlates the target capacity and the target time. The correlation between the target capacity and the target time may be determined by experimentation on a battery manufactured to have the same electrochemical performance as battery B.

[0069] Alternatively, each time a balancing execution command is received, the balancer 130 may perform the balancing process on the target battery B for a first time period, and then stop the balancing process for a second time period. The control circuit 140 may control the balancing of the plurality of batteries B1 to B2 for each period during which the balancing process of the balancer 130 is stopped. N The target battery B may be further identified from the battery groups, and a balancing instruction for the target battery B may be transmitted to the balancer 130.

[0070] The balancing command may be a high-level voltage applied directly to the discharge switch 132 to induce the discharge switch 132 from an off state to an on state. The discharge switch 132 may be maintained in an off state while the balancing command is not received.

[0071] Meanwhile, when a switch from an unloaded state to a loaded state is requested while the balancing process for the target battery B is being performed, the control circuit 140 may output a balancing stop command from the balancer 130. In response to the balancing stop command, the balancer 130 controls the plurality of batteries B1 to B2 to stop the balancing. NThe overall balancing process may then be completed.

[0072] 2 is a reference diagram for explaining an exemplary equivalent circuit of a battery. In this specification, a normal battery is a battery B1 to B2. N The faulty battery refers to the battery without internal short circuit failure. N This refers to batteries that have an internal short circuit.

[0073] Referring to Figure 2, a normal battery is connected to a DC voltage source V DC , and an RC pair R1, C. In contrast, the faulty battery has an additional resistance R ISC can be equivalent to the additional resistor R ISC is the leakage current I ISC For reference, the DC voltage source V DC The voltage of is the OCV of battery B, and the battery voltage is the DC voltage source V DC , is the total voltage of the internal resistance component R0 and the series circuit of the RC pair R1, C. When the voltage of the RC pair R1, C is zero (0V), the relaxation voltage and OCV are the same.

[0074] When charging the faulty battery, part of the charging power remains unstored in the faulty battery and generates a leakage current I ISC Furthermore, when the faulty battery is discharged, a part of the discharged power is not supplied to the electric load 30, and a leakage current I ISC Resistance R ISC The decrease in the resistance value of means that the internal short circuit fault becomes more severe, and the more severe the internal short circuit fault becomes, the greater the leakage current I ISC This can increase the amount of power consumed.

[0075] As a result, the voltage change (i.e., the increase in SOC) of the faulty battery is smaller than that of the normal battery during charging. On the other hand, the voltage change (i.e., the decrease in SOC) of the faulty battery is larger than that of the normal battery during discharging. Furthermore, even under no load, the energy stored in the faulty battery is leaked through the leakage current I ISC It will be consumed as.

[0076] 3 to 6 are reference diagrams for explaining the principle of detecting an internal short circuit fault in a battery.

[0077] FIG. 3 shows the battery B over a period of time in which the battery group 11 is sequentially subjected to a loaded (charging), unloaded, loaded (discharging) and unloaded conditions. i and Battery B j The graph shows the no-load voltage of each battery over time. i is a normal battery, and battery B j It is assumed that this is a faulty battery.

[0078] Referring to FIG. 3, curve 310 represents the time for which battery B i The no-load voltage of battery B is shown in curve 320. j The time point tB indicates the no-load voltage of the plurality of batteries B1 to B2. N The time tA is the time when a faulty battery is detected. REF The reference time Δt is the time in the past that precedes the reference time Δt. REF For ease of understanding, at time tA, the length of time i and Battery B j It is assumed that the no-load voltages of the

[0079] The period from time tA to time t1 is the charging period, and battery B i and Battery B j The no-load voltage of battery B continues to rise. j Battery B iThe no-load voltage rises more slowly than battery B during the charging period tA to t1. i and Battery B j That is, during the charging period tA to t1, the voltage difference between the batteries B1 to B N The voltage imbalance condition becomes increasingly severe.

[0080] The period from time t1 to time t4 is a no-load period, and battery B i and Battery B j Charging and discharging of Battery B will be interrupted. j The no-load voltage of battery B gradually drops during the no-load period t1 to t4 due to leakage current (see Figure 2). i The period during which the balancing process for battery B is performed. i The control circuit 140 controls the balancing of the plurality of batteries B1 to B2 between time t1 and time t2. N Among them, battery B i is set as the target battery. For example, at time t1, battery B j The no-load voltage of multiple batteries B1~B N If the minimum no-load voltage of battery B is i The no-load voltage of battery B j Since the no-load voltage of battery B is higher than that of i Of course, at least one battery among the remaining batteries whose no-load voltage is detected to be lower than the minimum no-load voltage may be further set as the target battery. i By balancing the battery B i The no-load voltage of the batteries B1 to B2 continues to decrease during the balancing period t2 to t3. N The voltage imbalance condition is gradually resolved.

[0081] The period from time t4 to time t5 is the discharging period, and battery B i and Battery B jThe no-load voltage of Battery B continues to decrease. j Battery B i The no-load voltage drops faster than battery B during the discharge period t4 to t5. i and Battery B j That is, during the discharging period t4 to t5, the voltage difference between the batteries B1 to B N The voltage imbalance condition becomes increasingly severe.

[0082] The period from time t5 to time tB is a no-load period. j The no-load voltage of battery B gradually decreases during the no-load period t5 to tB. i The control circuit 140 controls the balancing of the plurality of batteries B1 to B2 between time t5 and time t6. N In one example, at time t6, similar to time t2, the target battery is set to i is set to the target battery. Battery B i By balancing the battery B i The no-load voltage of the batteries B1 to B2 continues to decrease during the balancing period t6 to t7. N The voltage imbalance condition will be further resolved.

[0083] According to the description above with reference to FIG. 3, battery B i Each time a balancing process is performed on battery B, i and Battery B j As a result, the difference in no-load voltage between the batteries B1 to B2 at time tB (the timing of detecting an internal short circuit fault) decreases. N Simply comparing the no-load voltage of battery B to a critical value j However, there is a problem in that it is impossible to distinguish whether a battery is faulty or not.

[0084] The present invention uses the detection timing (time tB) of the internal short circuit fault as a reference and calculates the most recent reference time ΔtREF A plurality of batteries B1 to B in a period (i.e., tA to tB) N Using the balancing capacity of each of the batteries B1 to B2 at the detection timing (time tB), N The compensated voltage value of battery B indicates an estimated value of the no-load voltage of battery B at the detection timing (time tB) in the case where no balancing process is performed on battery B over the period tA to tB. This allows the no-load voltage of each of the batteries B1 to B2 at the detection timing (time tB) to be N Even if the voltage imbalance between battery B is very weak, j may be detected as a faulty battery.

[0085] The control circuit 140 detects the voltages of the plurality of batteries B1 to B2 at predetermined time intervals. N In one example, a reference time Δt REF may be 100 times the time interval between two adjacent detection timings, and the most recent reference time Δt REF The period can be specified using a moving window. The control circuit 140 can detect an internal short circuit fault when a detection implementation condition is satisfied. The detection implementation condition can be, for example, N It may be in a no-load state where the balancing process is stopped for the entire system.

[0086] The balancing capacity of battery B during the period tA to tB is the cumulative value of the discharge capacity of battery B due to the balancing process performed during the period tA to tB, that is, the total discharge capacity during the period tA to tB. j ) balancing capacity is determined to be 0 Ah.

[0087] The principle of determining the discharge capacity each time the balancing process is performed will be described below.

[0088] Figure 4 shows the load of battery B during the no-load period t1 to t4 in Figure 3. iThe curves 410 and 411 are diagrams for explaining the balancing process performed on battery B. i The graph shows the change in no-load voltage and discharge capacity over time for Battery B. i The voltage value of the no-load voltage of battery B is constant as V2 from time t1 to time t2, and continues to decrease from time t2 to time t3, reaching V3 at time t3. i This is the point at which the balancing process for

[0089] The control circuit 150 applies a capacity estimation function to the first balancing data of the balancing process to estimate the capacity of the battery B i The first balancing data includes a starting voltage value and a duration of the balancing process. The starting voltage value is the discharge capacity of battery B at the start time t2 of the balancing process. i The no-load voltage of the load is V2 in FIG. 4. The duration is the time interval from the start time t2 to the end time t3 of the balancing process, and is Δt BC =t3-t2.

[0090] The capacity estimation function defines the correlation between the starting voltage value, duration, and discharge capacity, and can be determined by experiments on a battery manufactured to have the same electrochemical performance as battery B. The following equation 1 is an example of the capacity estimation function.

[0091]

number

[0092] In equation 1, V start is the starting voltage value, Δt BC is the duration, R is the predetermined resistance of the discharge resistor 131, and Q dis is the discharge capacity per balancing process. V start / R denotes the balancing current that flows through the discharge resistor 131 at the start of the balancing process.

[0093] Equation 2 below is another example of a capacity estimation function.

number

[0094] In equation 2, V end is the end voltage value, and the remaining factors are the same as in equation 1.

[0095] Alternatively, the control circuit 150 may apply the SOC-OCV map to the second balancing data of the balancing process to calculate the SOC-OCV of the battery B i The second balancing data includes a start voltage value and an end voltage value of the balancing process. The end voltage value indicates the no-load voltage at the end time t3 of the balancing process, which is V3 in FIG. 4. FIG. 5 is an example of an SOC-OCV map. Referring to FIG. 5, Z2 is the SOC corresponding to the start voltage value V2, and Z3 is the SOC corresponding to the end voltage value V3. The control circuit 140 calculates the SOC of the battery B by subtracting Z2 from Z3, which is the difference between the two SOCs. i The full charge capacity (FCC) of battery B is multiplied by the full charge capacity (FCC) of battery B during the balancing process performed during the balancing period t2 to t3. i The discharge capacity of the battery can be determined. The method for estimating the full charge capacity is well known, so a detailed description thereof will be omitted.

[0096] Alternatively, the balancing capacity of battery B can be directly calculated by accumulating the balancing current, which is calculated periodically by applying Ohm's law to the voltage and resistance value of discharge resistor 131 from the start to the end of the balancing process.

[0097] The above-described determination of the balancing capacity can be performed each time the balancing process is performed.

[0098] During the period tA to tB, battery B iThe balancing process for battery B was performed twice. As a result, the control circuit 140 calculates the total discharge capacity of battery B during the period tA to tB by combining the discharge capacity during the balancing period t2 to t3 and the discharge capacity during the balancing period t6 to t7. i The total capacity consumed from battery B i The balancing capacity of the

[0099] Referring to FIG. 5, the control circuit 140 detects the voltages of the plurality of batteries B1 to B2 at the detection timing (time point tB). N An estimate of the SOC of each battery may be determined. i The no-load voltage is V i If so, the control circuit 140 adjusts the voltage value V i Apply the SOC-OCV map to the voltage value V i Z corresponding to i Battery B i can be determined as an estimate of the SOC.

[0100] The control circuit 140 calculates the most recent reference time Δt based on the detection timing (time point tB). REF Multiple batteries between B1 and B N A predetermined voltage compensation logic, which will be described later, is applied to each balancing capacity of the plurality of batteries B1 to B N Specifically, the control circuit 140 can compensate for the voltage value of the no-load voltage of each of the batteries B i The balancing capacity of battery B i Divide the full charge capacity of battery B i SOC change ΔZ i The control circuit 140 may determine the estimated SOC Z i SOC change amount ΔZ i and battery B i The estimated SOC value of Z i From Z i+ The control circuit 140 calculates the compensated SOC estimate Z i+ Apply the SOC-OCV map to Z i+ The voltage value V corresponding to i+ Determine the voltage value V i+Battery B i Using the balancing capacitance of i On the other hand, battery B j For battery B, no balancing process has been performed during the period tA to tB. j The compensated voltage value V j+ is the voltage value V detected at time tB j is the same as

[0101] 3, curve 311 corresponds to curve 310 plus battery B i The curve 311 is the result of applying the time-dependent change in the balancing capacity of the battery B during the period tA to tB to compensate the curve 310. i When no balancing process is performed on battery B, i 5 shows the change over time in the no-load voltage of battery B. Since no balancing process is performed during the charging period tA to t1, curves 310 and 320 are completely overlapped during the charging period tA to t1. Furthermore, since no balancing process is performed during the discharging period t4 to t5, the difference between curves 310 and 320 remains the same throughout the discharging period t4 to t5. As explained in FIG. 5, the no-load voltage of battery B at detection timing tB is i The voltage value is V i From V i+ By being compensated for by battery B j Voltage value V j It can be seen that the difference between

[0102] The above-mentioned series of processes (voltage compensation logic) is performed for multiple batteries B1 to B2 at each detection timing. N The control circuit 140 controls the plurality of batteries B1 to B2 at each detection timing. N The reference voltage value may be determined to be equal to the average or median of the compensated voltage values ​​of two or more batteries B1 to B2. That is, the reference voltage value may be updated at each detection timing. NThe voltage V may be (i) all of the plurality of compensated voltage values ​​or (ii) the average or median of a predetermined number of compensated voltage values ​​in descending order from the plurality of compensated voltage values. R is the reference voltage value at time tB. Alternatively, the reference voltage value is the value of each of the plurality of batteries B1 to B N can be a predetermined value regardless of voltage changes.

[0103] The control circuit 140 may determine a voltage difference, which is the difference between the reference voltage value and the compensated voltage value of the battery B, at each detection timing. The control circuit 140 may also determine a voltage difference, which is the difference between the reference voltage value and the compensated voltage value of the battery B, at the most recent reference time Δt REF A time series showing the time-dependent change in the voltage difference of battery B determined sequentially multiple times over the period tA to tB may be recorded in memory 141. If the voltage difference of battery B at some detection timings within the period tA to tB is missing, the missing voltage difference value may be added to the time series by applying interpolation to the remaining voltage difference values ​​in the time series. In FIG. 6, curves 610 and 620 are respectively the voltage difference of battery B. i and battery B j The graph shows the change in voltage difference over time.

[0104] The control circuit 140 calculates the most recent reference time Δt REF In FIG. 6, the amount of change in the voltage difference of battery B between ΔV iA and ΔV iB are the currents of battery B at time tA and tB, respectively. i is the voltage difference between battery B i The change in voltage difference is ΔV iA -ΔV iB Also, ΔV jA and ΔV jB are the currents of battery B at time tA and tB, respectively. j is the voltage difference between battery B j The change in voltage difference is ΔV jA -ΔV jB Incidentally, referring to Figure 3, ΔV iB =V i+ -V R and ΔV jB =Vj+ -V R is.

[0105] The control circuit 140 compares the change in the voltage difference of battery B with a critical value at each detection timing to determine whether battery B has an internal short circuit fault. iA -ΔV iB < Critical value ≦ ΔV jA -ΔV jB If so, battery B i is judged as a normal battery, and battery B j is determined to be a faulty battery.

[0106] The control circuit 140 compares the change in the voltage difference of battery B with a critical value at each detection timing, counts the number of consecutive times that the change in the voltage difference of battery B is equal to or greater than the critical value, and when the counted number reaches a predetermined number, it can determine that battery B has an internal short circuit fault.

[0107] 7 and 8 are flowcharts illustrating a battery management method according to a first embodiment of the present invention. The method of FIG. 7 may be repeatedly performed at predetermined time intervals. For ease of understanding, the method of FIG. 7 will be described assuming that it is performed at time tB.

[0108] 1 to 7, in step S700, the control circuit 140 determines a first voltage value representing the no-load voltage of the battery B. For example, V i and V j are battery B i and Battery B j 1 shows a first voltage value.

[0109] In step S710, the control circuit 140 compensates for the first voltage value of battery B using the balancing capacity of battery B. Step S710 may include steps S810, S820, S830, and S840 shown in FIG. 8 as subroutines.

[0110] In step S810, the control circuit 140 applies the SOC-OCV map to the first voltage value of battery B to determine an estimated value of the SOC of battery B. Referring to FIG. 5, Z i Battery B i The first voltage value V i Compatible battery B i This is an estimate of the SOC.

[0111] In step S820, the control circuit 140 determines the balancing capacity of battery B. The balancing capacity of battery B is calculated based on the most recent reference time Δt REF It may be the cumulative value of the discharge capacity due to the balancing process performed on battery B during

[0112] In step S830, the control circuit 140 compensates the estimated value of the SOC of the battery B by adjusting the SOC change amount corresponding to the balancing capacity to the estimated value of the SOC of the battery B. Referring to FIG. i to ΔZ i is added, and battery B i The compensated SOC estimate Z i+ is obtained.

[0113] In step S840, control circuit 140 applies the SOC-OCV map to the compensated SOC estimate of Battery B to determine a compensated first voltage value of Battery B. Referring to FIG. 5, the compensated first voltage value of Battery B is Z i+ V corresponding to i+ is determined identically to

[0114] In step S720, the control circuit 140 determines a reference voltage value. R is the reference voltage value at time tB.

[0115] In step S730, the control circuit 140 determines the voltage difference of battery B as the difference between the compensated first voltage value of battery B and the reference voltage value. Referring to FIG. 6, ΔV iB and ΔV jB are battery B i and battery Bj is the voltage difference.

[0116] In step S740, the control circuit 140 calculates the most recent reference time Δt REF Determine the change in the voltage difference of Battery B between ΔV iA -ΔV iB Battery B i is the change in the voltage difference between jA -ΔV jB Battery B j is the change in the voltage difference.

[0117] In step S750, the control circuit 140 determines whether the change in the voltage difference of battery B is equal to or greater than a critical value. If the value of step S750 is 'YES', the control circuit 140 proceeds to step S760.

[0118] In step S760, the control circuit 140 detects that Battery B has an internal short circuit fault. Furthermore, the control circuit 140 may perform a predetermined protective action. The protective action may be the output of a diagnostic message indicating that Battery B has an internal short circuit fault. The diagnostic message may be transmitted to the vehicle controller 2 by the communication circuit 150. Upon receiving the diagnostic message, the communication circuit 150 may output a warning signal to the user.

[0119] 9 is a flowchart illustrating a battery management method according to a second embodiment of the present invention. The method of FIG. 9 may be repeatedly performed at predetermined time intervals. For ease of understanding, the method of FIG. 9 will be described assuming that it is performed at time tB.

[0120] 9, steps S700 to S740 are the same as those in the first embodiment. After step S740 is performed, the process proceeds to step S910. In step S910, control circuit 140 determines whether the amount of change in the voltage difference of battery B is equal to or greater than a critical value. If the value of step S910 is "yes," the process proceeds to step S920. If the value of step S910 is "no," the process proceeds to step S922.

[0121] In step S920, the control circuit 140 increments the failure count of battery B by 1. In step S922, the control circuit 140 resets the failure count of battery B to the same as the initial value (eg, 0).

[0122] In step S930, control circuit 140 determines whether the failure count of battery B is equal to or greater than a predetermined value. That is, it determines whether the change in the voltage difference of battery B is equal to or greater than a critical value and has been counted a predetermined number of times in succession. If the value of step S930 is "YES," the process proceeds to step S940.

[0123] In step S940, the control circuit 140 detects an internal short circuit fault in the battery B. As in the first embodiment, the control circuit 140 can perform a predetermined protective operation.

[0124] The second embodiment is a modification of the first embodiment, which can prevent detection of a faulty battery.

[0125] The embodiments of the present invention described above are not necessarily embodied through devices and methods, but may be embodied through a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation should be easily embodied by a person skilled in the art to which the present invention pertains from the description of the above-mentioned embodiments.

[0126] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the scope of the claims.

[0127] Furthermore, since the above-mentioned present invention can be variously replaced, modified, and changed by a person having ordinary knowledge in the technical field to which the present invention belongs without departing from the technical concept of the present invention, it is not limited to the above-mentioned embodiments and the attached drawings, and can be configured by selectively combining all or part of each embodiment to make various modifications. [Item 1] a battery monitor that detects the voltage of each of the plurality of batteries connected in series; A balancer that performs balancing processing for each battery, a control circuit that controls the balancer based on the voltage of each battery detected by the battery monitor; The control circuit determining a first voltage value indicative of a no-load voltage of each of the batteries; Compensating the first voltage value of each battery using a balancing capacity of each battery according to the balancing process performed during a recent reference time; determining a voltage difference between the compensated first voltage value and a reference voltage value for each battery; a battery management system that detects an internal short circuit fault in each of the batteries by comparing a change in the voltage difference of each of the batteries during the reference time with a critical value; [Item 2] The control circuit If the change in the voltage difference of each battery is equal to or greater than the critical value, increasing a failure count of each battery by 1; Item 1. The battery management system according to item 1, wherein if the failure count of each battery is equal to or greater than a predetermined value, each battery is detected as having an internal short circuit failure. [Item 3] The control circuit Item 1. The battery management system according to item 1, wherein the reference voltage value is determined to be equal to an average or median value of the compensated first voltage values ​​of at least two or more batteries among the plurality of batteries. [Item 4] the balancer includes a plurality of balancing circuits connected in parallel to the plurality of batteries in a one-to-one relationship; Item 1. The battery management system of item 1, wherein each balancing circuit includes a discharge resistor and a discharge switch connected in series. [Item 5] The control circuit 2. The battery management system according to claim 1, wherein the balancing capacity of each battery cell is determined by accumulating the discharge capacity of each battery cell due to each balancing process performed within the reference time period. [Item 6] The control circuit applying a capacity estimation function to first balancing data associated with each balancing process to determine the discharge capacity of each battery associated with each balancing process; 6. The battery management system according to item 5, wherein the first balancing data includes a second voltage value indicating a no-load voltage of each of the batteries at the start of the balancing process and a duration of the balancing process. [Item 7] The control circuit applying a SOC-OCV map to the second balancing data for each balancing process to determine the discharge capacity of each battery for each balancing process; 6. The battery management system of claim 5, wherein the second balancing data includes a second voltage value indicating a no-load voltage of each of the batteries at the start of the balancing process and a third voltage value indicating a no-load voltage of each of the batteries at the end of the balancing process. [Item 8] The control circuit applying a SOC-OCV map to the first voltage value of each battery to determine an estimated SOC for each battery; Compensating the estimated value of the SOC of each battery by adjusting the SOC change amount corresponding to the balancing capacity to the estimated value of the SOC of each battery; 2. The battery management system of claim 1, wherein the compensated first voltage value is determined by applying the SOC-OCV map to the compensated SOC estimate of each battery. [Item 9] 9. A battery pack comprising the battery management system according to any one of items 1 to 8. [Item 10] 10. An electric vehicle including the battery pack according to item 9. [Item 11] determining a first voltage value indicative of a no-load voltage of each of the plurality of series connected batteries; compensating the first voltage value of each battery using a balancing capacity of each battery according to a balancing process performed during a recent reference time; determining a voltage difference between the compensated first voltage value and a reference voltage value for each battery; and comparing a change in the voltage difference of each of the batteries during the reference time with a critical value to detect an internal short circuit fault in each of the batteries. [Item 12] The step of detecting an internal short circuit fault of each battery comprises: increasing a failure count of each battery by 1 if the change in the voltage difference of each battery is equal to or greater than the critical value; 12. The battery management method according to item 11, further comprising: detecting each battery as having an internal short circuit fault if the fault count of each battery is equal to or greater than a predetermined value. [Item 13] 13. The battery management method according to claim 11 or 12, further comprising determining the reference voltage value to be equal to an average or median of the compensated first voltage values ​​of at least two or more batteries among the plurality of batteries. [Item 14] The step of compensating the first voltage value of each battery includes: applying a SOC-OCV map to the first voltage values ​​of each battery to determine an estimated SOC for each battery; Compensating the estimated SOC of each battery by adjusting the SOC change amount corresponding to the balancing capacity to the estimated SOC of each battery; and applying the SOC-OCV map to the compensated SOC estimate for each battery to determine the compensated first voltage value.

Claims

1. at least one processor; a memory storing at least one instruction executed by the at least one processor, The at least one instruction, when executed by the at least one processor, causes the at least one processor to: obtaining a no-load voltage value of each of a plurality of batteries; When a balancing process has not been performed on the plurality of batteries, the no-load voltage value of each battery is compensated for using the balancing capacity of each battery obtained by a balancing process performed in the past; determining a voltage difference between the compensated no-load voltage value and a reference voltage value of at least one battery among the plurality of batteries; a battery management system that detects whether or not there is an abnormality in the at least one battery based on the amount of change in the voltage difference of the at least one battery;

2. The at least one instruction, when executed by the at least one processor, causes the at least one processor to: If the change in the voltage difference of the at least one battery is equal to or greater than a critical value, increasing a failure count of the at least one battery by one; The battery management system of claim 1 , wherein when a failure count of the at least one battery is equal to or greater than a predetermined value, the at least one battery is detected as having an internal short circuit failure.

3. The reference voltage value is The battery management system of claim 1 , wherein the compensated no-load voltage value is an average or median value of the compensated no-load voltage values ​​of at least two or more batteries among the plurality of batteries.

4. The at least one instruction, when executed by the at least one processor, causes the at least one processor to: Compensating the no-load voltage value using a balancing capacitance obtained by a balancing process performed during a reference time; The reference time is The battery management system of claim 1 , wherein the time is longer than the time for performing the balancing process.

5. The at least one instruction, when executed by the at least one processor, causes the at least one processor to: The battery management system according to claim 1 , wherein the balancing capacity of each battery is determined by accumulating the discharge capacity of each battery due to each balancing process performed within a reference time period.

6. The at least one instruction, when executed by the at least one processor, causes the at least one processor to: applying a capacity estimation function to first balancing data associated with each balancing process to determine the discharge capacity of each of the batteries associated with each balancing process; The battery management system of claim 5 , wherein the first balancing data includes a no-load voltage value of each of the batteries at the start of the balancing process and a duration of the balancing process.

7. The at least one instruction, when executed by the at least one processor, causes the at least one processor to: applying an SOC-OCV map to the second balancing data of each balancing process to determine the discharge capacity of each battery for each balancing process; The battery management system of claim 5 , wherein the second balancing data includes a no-load voltage value of each of the batteries at the start of the balancing process and a no-load voltage value of each of the batteries at the end of the balancing process.

8. The at least one instruction, when executed by the at least one processor, causes the at least one processor to: determining an estimated value of SOC of each battery by applying an SOC-OCV map to the no-load voltage value of each battery; Compensating the estimated value of SOC of each battery by adjusting the SOC change amount corresponding to the balancing capacity to the estimated value of SOC of each battery; The battery management system of claim 1 , further comprising: applying the SOC-OCV map to the compensated SOC estimate of each battery to determine the compensated no-load voltage value.

9. A battery pack comprising the battery management system according to any one of claims 1 to 8.

10. An electric vehicle comprising the battery pack of claim 9.

11. obtaining a no-load voltage value for each of the plurality of batteries; compensating the no-load voltage value of each battery using a balancing capacity of each battery obtained by a previous balancing process when a balancing process has not been performed on the plurality of batteries; determining a voltage difference between the compensated no-load voltage value and a reference voltage value of at least one battery among the plurality of batteries; detecting whether or not there is an abnormality in the at least one battery based on a change in the voltage difference of the at least one battery.

12. The step of detecting whether or not there is an abnormality in the at least one battery comprises: increasing a failure count of the at least one battery by 1 if the change in the voltage difference of the at least one battery is equal to or greater than a critical value; 12. The battery management method of claim 11, further comprising: detecting the at least one battery as having an internal short circuit fault if the fault count of the at least one battery is equal to or greater than a predetermined value.

13. The reference voltage value is The battery management method according to claim 11 or 12, wherein the compensated no-load voltage values ​​of at least two or more batteries among the plurality of batteries are an average value or a median value.

14. The step of compensating the no-load voltage value of each battery includes: determining an estimated SOC value for each battery by applying an SOC-OCV map to the no-load voltage value for each battery; Compensating the estimated value of SOC of each battery by adjusting the SOC change amount corresponding to the balancing capacity to the estimated value of SOC of each battery; and applying the SOC-OCV map to the compensated SOC estimate of each battery to determine the compensated no-load voltage value.

15. A program that, when executed by at least one processor, causes the at least one processor to perform the battery management method according to claim 11 or 12.

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