Busbar diagnostic device, battery pack, energy storage system, and busbar diagnostic method

Abstract

A busbar diagnostic apparatus according to an aspect of the disclosure includes a plurality of voltage sensing pins, a battery monitoring circuit, a voltage sensing channel, a bypass unit, and a control circuit that diagnoses a busbar. According to an embodiment of the disclosure, a voltage of each battery cell of a plurality of battery cells of a first battery module and a plurality of battery cells of a second battery module is detected using a potential difference of every two adjacent voltage sensing pins, and the busbar is diagnosed based on a voltage history of each battery cell of the plurality of battery cells.

Description

Technical Field

[0001] This application claims the benefit of Korean Patent Application No. 10-2021-0008928, filed with the Korean Intellectual Property Office on January 21, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to fault diagnosis of a busbar for connecting two battery modules in series. Background Technology

[0003] Recently, demand for portable electronic products such as laptops, video cameras and mobile phones has increased dramatically, and with the widespread development of electric vehicles, energy storage devices, robots and satellites, there is a great deal of research being conducted on high-performance batteries that can be repeatedly recharged.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have little to no memory effect, and therefore are gaining more attention than nickel-based batteries due to their advantages of easy recharging, very low self-discharge rate, and high energy density.

[0005] Recently, there has been a growing demand for battery packs that include two or more battery modules connected in series via busbars, each battery module comprising multiple battery cells connected in series, in order to provide high voltage.

[0006] However, busbars may fail due to external influences or aging of the busbars themselves. When a busbar fails, the safety of the battery pack decreases, thus necessitating a method for accurate busbar fault diagnosis.

[0007] Patent document 1 discloses a method for detecting busbar faults based on the voltage across the busbar itself or the voltage across the series-connected battery cells and the busbar assembly. However, busbar voltage measurement, which is independent of the voltage measurement of the battery cells, is inefficient.

[0008] (Patent Document 1) Korean Patent Publication No. 10-2012-0080315 (published on July 17, 2012). Summary of the Invention

[0009] Technical issues

[0010] This disclosure is designed to solve the above-mentioned problems, and therefore relates to providing a busbar diagnostic device, battery pack, energy storage system, and busbar diagnostic method for diagnosing busbar faults based on the voltage history of two battery cells, each connected to one of the two ends of the busbar, without the need for a process of measuring the voltage of the busbar.

[0011] These and other objectives and advantages of this disclosure will be understood from the following detailed description and will be apparent from embodiments of this disclosure. Furthermore, it will be readily understood that the objectives and advantages of this disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

[0012] Technical solution

[0013] A busbar diagnostic device according to an aspect of the present disclosure is provided for a battery pack including a busbar connected between a positive terminal of a first battery module comprising a plurality of battery cells connected in series and a negative terminal of a second battery module comprising a plurality of battery cells connected in series. The busbar diagnostic device includes: a battery monitoring circuit comprising a plurality of voltage sensing pins and configured to detect the voltage of each of a plurality of battery cells in a first battery module and a plurality of battery cells in a second battery module using the potential difference between every two adjacent voltage sensing pins; a voltage sensing channel comprising a plurality of voltage sensing lines connecting the positive and negative terminals of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module to the plurality of voltage sensing pins; a bypass unit connected to the busbar via a first voltage sensing pin and a second voltage sensing pin among the plurality of voltage sensing pins, wherein the first voltage sensing pin is connected to the positive terminal of the upstream battery cell in the first battery module via one of the plurality of voltage sensing lines, and the second voltage sensing pin is connected to the negative terminal of the downstream battery cell in the second battery module via another of the plurality of voltage sensing lines; and a control circuit configured to diagnose the busbar based on the voltage history of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module detected by the battery monitoring circuit.

[0014] The bypass unit may include a diode. The anode and cathode of the diode may be connected to a first voltage sensing pin and a second voltage sensing pin, respectively.

[0015] Each voltage sensing line may include a protective resistor with a predetermined resistance value.

[0016] The battery monitoring circuit may further include a pair of current sensing pins connected to the current path of the battery pack. The battery monitoring circuit can be configured to use the potential difference between the pair of current sensing pins to detect the current flowing through the current path.

[0017] The control circuit can be configured to: when it is determined that the battery pack is kept in discharge mode for a set time or more, at each predetermined diagnostic time, determine the average voltage of multiple battery cells of the first battery module and multiple battery cells of the second battery module; when both the difference between the voltage of the upstream battery cell of the first battery module and the average voltage and the difference between the voltage of the downstream battery cell of the second battery module and the average voltage are greater than a reference voltage difference, increment the diagnostic count by a predetermined value; and when the incremented diagnostic count is equal to or greater than the reference count, set a diagnostic flag indicating that the busbar is in a fault state.

[0018] The control circuit can be configured to set the diagnostic count to an initial value smaller than the reference count when at least one of the difference between the voltage of the upstream cell of the first battery module and the average voltage and the difference between the voltage of the downstream cell of the second battery module and the average voltage is equal to or less than the reference voltage difference.

[0019] The control circuit can be configured to: when it is determined that the battery pack switches from rest mode or charging mode to discharging mode, determine the voltage drop of the upstream battery cell in the first battery module, the voltage drop of the downstream battery cell in the second battery module, and the average voltage drop of multiple battery cells in the first battery module and the second battery module during the diagnostic time; and when both the difference between the voltage drop of the upstream battery cell in the first battery module and the average voltage drop and the difference between the voltage drop of the downstream battery cell in the second battery module and the average voltage drop are greater than a reference voltage drop, set a diagnostic flag indicating that the busbar is in a fault state.

[0020] The control circuit can be configured to determine a reference voltage drop by multiplying the change in current over the diagnostic time by a predetermined conversion factor when it is determined that the battery pack is switching from a rest mode or a charging mode to a discharging mode.

[0021] According to another aspect of this disclosure, a battery pack includes the busbar diagnostic device.

[0022] According to another aspect of this disclosure, an energy storage system includes the battery pack.

[0023] A busbar diagnostic method according to another aspect of this disclosure is provided, which can be performed by the busbar diagnostic device. The busbar diagnostic method includes: a battery monitoring circuit using the potential difference between every two adjacent voltage sensing pins of a plurality of voltage sensing pins to detect the voltage of each of a plurality of battery cells in a first battery module and a plurality of battery cells in a second battery module; and a control circuit diagnosing the busbar based on the voltage history of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module detected by the battery monitoring circuit.

[0024] Beneficial effects

[0025] According to at least one embodiment of this disclosure, fault diagnosis of the busbar can be achieved based on the voltage history of two battery cells, each connected to one of the two ends of the busbar, without the need for a process of measuring the voltage of the busbar.

[0026] According to at least one embodiment of this disclosure, more accurate fault diagnosis of the busbar can be achieved by adjusting a reference (e.g., a reference voltage drop as described below) based on the time-varying current of the battery pack to determine whether the busbar is faulty.

[0027] The effects of this disclosure are not limited to those described above, and these and other effects will be clearly understood by those skilled in the art from the appended claims. Attached Figure Description

[0028] The accompanying drawings illustrate preferred embodiments of the present disclosure and are used together with the detailed description of the present disclosure below to provide a further understanding of the technical aspects of the present disclosure; therefore, the present disclosure should not be construed as limited to the drawings.

[0029] Figure 1 This is an exemplary diagram illustrating the architecture of an energy storage system according to this disclosure.

[0030] Figure 2 It is used in describing Figure 1 The figure shown in the diagram illustrates the relationship between the fault status of the busbar and the voltage detection error of the battery cell.

[0031] Figure 3 This is an exemplary flowchart of a busbar diagnostic method according to the present disclosure.

[0032] Figure 4 It shows the method used for execution. Figure 3 A schematic flowchart of the fault detection process in the first embodiment of step S320.

[0033] Figure 5 It shows the method used for execution. Figure 3A schematic flowchart of the fault detection process in the second embodiment of step S320. Detailed Implementation

[0034] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in this specification and the appended claims should not be construed as limited to their general and dictionary meanings, but rather interpreted based on their meanings and concepts corresponding to the technical aspects of the present disclosure, while allowing the inventors to appropriately define the terms for the best illustration.

[0035] Therefore, the embodiments described herein and the illustrations shown in the accompanying drawings are merely the most preferred embodiments of this disclosure and are not intended to fully describe the technical aspects of this disclosure. It should be understood that various other equivalents and modifications can be made thereto when this application is filed.

[0036] Ordinal terms, such as “first” and “second”, are used to distinguish one element from another among various elements, rather than to limit these elements.

[0037] Unless the context clearly indicates otherwise, it will be understood that the term "comprising" as used in this specification specifies the presence of the stated element, but does not exclude the presence or addition of one or more other elements. Additionally, as used herein, the term "control circuitry" refers to a processing unit with at least one function or operation, and may be implemented by hardware and software, alone or in combination.

[0038] Furthermore, throughout this specification, when an element is referred to as being “connected” to another element, it can be directly connected to the other element or there may be an intermediary element.

[0039] Figure 1 This is an exemplary diagram illustrating the architecture of an energy storage system according to this disclosure.

[0040] refer to Figure 1 The energy storage system 1 includes a battery pack 10, a relay 20, and a power conversion system 30.

[0041] The battery pack 10 includes a first battery module 11, a second battery module 12, a busbar 13, and a busbar diagnostic device 100.

[0042] The series circuit of the first battery module 11, the busbar 13, and the second battery module 12 can be electrically connected to the power conversion system 30 via the relay 20.

[0043] The first battery module 11 includes multiple battery cells C1 to C2 connected in series. m , where m is a natural number of 2 or greater. The second battery module 12 includes multiple battery cells C connected in series. m+1~C m+n , where n is a natural number of 2 or greater.

[0044] Multiple battery cells C1~C m and multiple battery cells C m+1 ~C m+n They can be manufactured using the same electrochemical specifications. In the following description, the description refers to all battery cells C1 to C1 included in battery pack 10. m+n In the common theme, the reference symbol 'C' is used to refer to a single battery cell.

[0045] The battery cell C is not limited to a specific type and can include any type of battery cell that can be repeatedly recharged, such as a lithium-ion cell.

[0046] In the first battery module 11, multiple battery cells C1 to C2 are included. m Each battery cell in the system has a positive electrode lead and a negative electrode lead, and the positive electrode lead of one battery cell (e.g., C1) and the negative electrode lead of the other battery cell (e.g., C2) in two adjacent battery cells (e.g., C1, C2) can be joined together by welding. Therefore, from the negative electrode lead of battery cell C1 to the negative electrode lead of battery cell C2... m The series connection structure of the positive electrode lead is located in the first battery module 11.

[0047] In the second battery module 12, multiple battery cells C m+1 ~C m+n Each cell in the battery has a positive lead and a negative lead, and two adjacent cells (e.g., C) m+1 C m+2 One of the battery cells (e.g., C) m+1 The positive lead of ) and another battery cell (e.g., C) m+2 The negative electrode leads of the battery cell C can be joined together by soldering. m+1 The negative electrode lead to the battery cell C m+n The series connection structure of the positive electrode lead is located in the second battery module 12.

[0048] In the following text, it should be noted that the positive and negative leads of the battery cell C can also be referred to as the "positive electrode" and the "negative electrode," respectively.

[0049] The positive terminal of the first battery module 11 is connected to the negative terminal of the second battery module 12 via a busbar 13. For example, one end of the busbar 13 is fixed by a bolt and coupled to the positive terminal of the first battery module 11, and the other end of the busbar 13 is fixed by a bolt and coupled to the negative terminal of the second battery module 12.

[0050] In each battery module 11, 12, the electrical location at a lower potential can be referred to as "downstream" and the opposite location can be referred to as "upstream". For example, battery cell C m Arranged at the uppermost position of the first battery module 11, and the battery cell C m+1 It is positioned at the downstream end of the second battery module 12. The positive terminal of the first battery module 11 may have a connection with the battery cell C. m The positive terminal of the second battery module 12 has the same potential as the positive terminal of the battery cell C, and the negative terminal of the second battery module 12 can have the same potential as the negative terminal of the battery cell C. m+1 The negative electrode has the same potential. When x is a natural number of 2 or greater and m+n or less, it can be said that the cell C has the same potential. x Arranged in battery cell C x-1 Upstream of, and battery cell C x-1 Arranged in battery cell C x Downstream of.

[0051] Relay 20 is installed on a power line configured as a current path for charging / discharging the battery pack 10. When relay 20 is turned on, power can be transferred from either the battery pack 10 or the power conversion system 30 to the other. Relay 20 may include at least one of well-known switching devices, such as a mechanical contactor and a field-effect transistor (FET). Control circuitry 140 can perform on / off control of relay 20 based on diagnostic results from busbar 13 as described below.

[0052] The power conversion system 30 is operably coupled to the busbar diagnostic device 100 via the upper-level controller 2. The power conversion system 30 can generate DC power from AC power supplied by the power grid 40 for charging the battery pack 10. The power conversion system 30 can also generate AC power from DC power from the battery pack 10.

[0053] Busbar diagnostic device 100 is configured to monitor for faults in busbar 13. A fault in busbar 13 is defined as an increase in the total resistance across busbar 13 from a predetermined initial value to an allowable value due to at least one of the following: (i) a defect in busbar 13 itself (e.g., a break), (ii) failure to couple to the positive terminal of the first battery module 11, and (iii) failure to couple to the negative terminal of the second battery module 12.

[0054] Busbar diagnostic device 100 includes a voltage sensing channel 110, a battery monitoring circuit 120, a bypass device 130, and a control circuit 140. Busbar diagnostic device 100 may further include at least one of a shunt resistor 150 or a communication circuit 160.

[0055] The battery monitoring circuit 130 includes multiple voltage sensing pins P0 to P10. m+n+1Multiple voltage sensing pins P0 to P1 m+n+1 It is configured to be electrically connected to multiple battery cells C1 to C2 via voltage sensing channel 110. m+n The battery monitoring circuit 120 includes positive and negative leads for each individual battery cell. The battery monitoring circuit 120 can be implemented in hardware using an application-specific integrated circuit (ASIC). For example, a BQ76940 can be used for the battery monitoring circuit 120.

[0056] Voltage sensing channel 110 may include multiple voltage sensing lines L0 to L1 m+n+1 Multiple voltage sensing lines L0~L m+n+1 Each voltage sensing line may include a protective resistor R with a predetermined resistance. The protective resistor R is configured to prevent overcurrent from passing through the voltage sensing line in which the protective resistor R is included.

[0057] One end of the voltage sensing line L0 is connected to the negative terminal of the battery cell C1 and the voltage sensing pin P0 of the battery monitoring circuit 120, respectively.

[0058] When i is a natural number m or smaller, the voltage sensing line L i One end and the other end are respectively connected to the battery cell C i The positive terminal and the voltage sensing pin P of the battery monitoring circuit 120 i .

[0059] Voltage sensing line L m+1 One end and the other end are respectively connected to the battery cell C m+1 The negative terminal and the voltage sensing pin P of the battery monitoring circuit 120 m+1 .

[0060] When j is a natural number that is m+2 or greater and m+n+1 or smaller, the voltage sensing line L j One end and the other end are respectively connected to the battery cell C j The positive terminal and the voltage sensing pin P of the battery monitoring circuit 120 j .

[0061] The battery monitoring circuit 120 uses multiple voltage sensing pins P0 to P1. m+n+1 The potential difference between any two adjacent voltage sensing pins is used to detect voltage differences across multiple battery cells C1 to C2. m+n The voltage of each individual battery cell in the system.

[0062] That is, when i is a natural number of m or less and j is a natural number of m+2 or greater and m+n+1 or less, the two voltage sensing pins P i-1 P i The potential difference between them was detected as the C of the battery cell.i The voltage, and the two voltage sensing pins P j-1 P j The potential difference between them was detected as the C of the battery cell. j-1 The voltage. In the example, the battery monitoring circuit 120 can sense the voltage between two adjacent voltage sensing pins P. m-1 P m The potential difference between them is detected by the cell C. m The voltage. In another example, the battery monitoring circuit 120 can sense the voltage of two adjacent voltage sensing pins P. m+1 P m+2 The potential difference between them is detected by the cell C. m+1 The voltage.

[0063] The control circuit 140 can collect voltage signals from the battery monitoring circuit 120 at set time intervals (e.g., 0.001 seconds) and determine the indications of multiple battery cells C1 to C2 via analog-to-digital conversion. m+n The voltage value of each individual battery cell in the system.

[0064] Bypass device 130 via a pair of voltage sensing lines L m L m+1 It is connected in parallel to busbar 13. Specifically, one end of the bypass device 130 and the other end are respectively connected to a pair of voltage sensing pins P. m P m+1 Therefore, a bypass device 130 and a voltage sensing pin P are formed. m+1 Voltage sensing line L m+1 Busbar 13, Voltage Sensing Line L m and voltage sensing pin P m The closed loop. When predetermined conditions for the bypass device 130 (e.g., battery pack discharge mode) are met, the two voltage sensing pins P... m P m+1 Electrically connected via bypass device 130. Conversely, when predetermined conditions for bypass device 130 are not met, the bypass device 130 is used to connect to the two voltage sensing pins P. m P m+1 The current path between them is blocked.

[0065] although Figure 1 A bypass device 130 is shown located outside the battery monitoring circuit 120; however, alternatively, the bypass device 130 may be integrated into the battery monitoring circuit 120 as a component of the battery monitoring circuit 120.

[0066] When busbar 13 is in normal condition, the resistance ratio of busbar 13 includes that of the two voltage sensing lines L m Lm+1 The resistance of the protective resistor R in the battery pack 10 is much smaller, and therefore all or most of the current flowing through the battery pack 10 passes through the busbar 13 and only 0A or a very small amount of current flows through the bypass device 130.

[0067] Conversely, when busbar 13 is in a fault state, (i) the resistance of busbar 13 itself, (ii) the contact resistance between one end of busbar 13 and the positive terminal of the first battery module 11, and / or (iii) the contact resistance between the other end of busbar 13 and the negative terminal of the second battery module 12 increases from the normal level. Therefore, as the fault state of busbar 13 becomes more severe, there is a gradual increase in the amount of current flowing through the bypass device 130 in the total current flowing through the battery pack 10.

[0068] The control circuit 140 is operatively coupled to the relay 20, the battery monitoring circuit 120, the shunt resistor 150, and / or the communication circuit 160.

[0069] The control circuit 140 can be implemented in hardware using at least one of the following: a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions.

[0070] The control circuit 140 may have an embedded memory. The memory may pre-store programs and data required to execute the battery management method according to the embodiments described below. The memory may include at least one type of storage medium, such as flash memory, hard disk, solid-state drive (SSD), silicon disk drive (SDD), multimedia card micro, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or programmable read-only memory (PROM).

[0071] Shunt resistor 150 is connected in series via power lines to the series circuit of the first battery module 11, busbar 13, and second battery module 12. Battery monitoring circuit 120 is connected to one end of shunt resistor 150 and the other end of the shunt resistor 150 via a pair of current sensing pins. Battery monitoring circuit 120 is configured to detect the current flowing through battery pack 10 based on the potential difference between the pair of current sensing pins and output a current signal indicating the detected current to control circuit 140.

[0072] Communication circuit 160 can be coupled to the upper-level controller 2 of energy storage system 1 to enable communication between them. Communication circuit 160 can send messages from upper-level controller 2 to control circuit 140 and vice versa. Messages from control circuit 140 may include information for notifying faults in busbar 13 and / or the voltage of battery cell C. For communication between communication circuit 160 and upper-level controller 2, wired networks such as local area networks (LAN), controller area networks (CAN), and daisy-chaining, and / or near-field wireless networks such as Bluetooth, Zigbee, and WiFi, can be used. Communication circuit 160 may include output devices (e.g., displays, speakers) that provide information received from control circuit 140 and / or upper-level controller 2 in a recognizable format. Upper-level controller 2 can control power conversion system 30 based on information collected through communication with busbar diagnostic device 100.

[0073] Figure 2 It is used in describing Figure 1 The figure shown in the diagram illustrates the relationship between the fault status of the busbar and the voltage detection error of the battery cell.

[0074] exist Figure 2 In the diagram, a diode for bypass device 130 is shown by way of illustration. The anode and cathode of the diode can be connected to the voltage sensing pin P, respectively. m and voltage sensing pin P m+1 In this configuration, the voltage across busbar 13 is applied as a forward voltage to the diode during the discharge of battery pack 10, and the diode conducts (conducts current). That is, the diode allows current to flow when battery pack 10 is in discharge mode, and as the diode conducts current, a current path is formed in parallel with busbar 13. Discharge mode refers to a mode in which power is supplied from battery pack 10 to the power conversion system through the flow of discharge current through the first battery module 11 and the second battery module 12.

[0075] refer to Figure 2 When busbar 13 is in a faulty state for some reason, the total resistance of busbar 13 increases from the initial value to above the allowable value as described above. The total resistance of busbar 13 is (i) the resistance of busbar 13 itself, and (ii) the resistance of the connection portion Q between one end of busbar 13 and the positive terminal of the first battery module 11. A The contact resistance at (iii) and the connection portion Q between the other end of busbar 13 and the negative terminal of the second battery module 12. B The sum of the contact resistances at each point.

[0076] In this case, the current I of battery pack 10P Equal to the current I flowing through busbar 13 A and the current I flowing through the bypass device 130 B The sum of the currents. When the bypass device 130 is turned on (conducting current), because the total resistance of the busbar 13 is relatively large, the current I flowing through the bypass device 130 is... B With the current I flowing through busbar 13 A The ratio I B / I A The value is larger depending on the resistance ratio between busbar 13 and the bypass path. The bypass path is the voltage sensing line L. m Bypass device 130 and voltage sensing line L m+1 The series connection path. That is, the current I B The flow through the bypass device 130 refers to the current I. B Through a pair of voltage sensing lines L m L m+1 The flow.

[0077] When the current I B Voltage sensing line L m At that time, in the battery cell C m The positive terminal and voltage sensing pin P m Interchange with current I B Multiply by the voltage drop V corresponding to the resistance of the protection resistor R. D Additionally, when the current I... B Voltage sensing line L m+1 At that time, at the voltage sensing pin P m+1 With battery cell C m+1 A current I occurs between the negative terminals. B Multiply by the voltage drop V corresponding to the resistance of the protection resistor R. D .

[0078] Therefore, the battery cell C detected by the battery monitoring circuit 120 m The voltage from the battery cell C m The actual voltage is reduced by up to [amount] on the voltage sensing line L m Pressure drop V at point D Additionally, the battery cell C detected by the battery monitoring circuit 120... m+1 The voltage also changes from the battery cell C m+1 The actual voltage is reduced by up to [amount] on the voltage sensing line L m+1 Pressure drop V at point D That is, in the battery cell C arranged at the uppermost end of the first battery module 11 m The voltage and the battery cell C arranged at the downstream end of the second battery module 12 m+1 An error occurred in the voltage detection result.

[0079] Figure 3 This is an exemplary flowchart of a busbar diagnostic method according to the present disclosure. Figure 4 It is based on the execution Figure 3 A schematic flowchart of the fault detection process in the first embodiment of step S320, and Figure 5 It is based on the execution Figure 3 A schematic flowchart of the fault detection process in the second embodiment of step S320. Figures 3 to 5 The method can be repeatedly performed by the busbar diagnostic device 100 at predetermined diagnostic times in a periodic manner. The diagnostic time can be equal to the predetermined time or can be preset as an integer multiple of the predetermined time.

[0080] refer to Figures 1 to 3 In step S310, the battery monitoring circuit 120 uses multiple voltage sensing pins P0 to P10. m+n+1 The potential difference between any two adjacent voltage sensing pins (e.g., P0, P1) is used to detect the potential difference between multiple battery cells C1 to C2 of the first battery module 11. m Multiple battery cells C of the second battery module 12 m+1 ~C m+n The control circuit 140 can collect the voltage of each individual battery cell C1 to C2 detected by the battery monitoring circuit 120. m+n The analog signal of the voltage of each battery cell C is collected, the collected analog signal is converted into a digital signal, and it is recorded in the memory as the latest value in the time series indicating the voltage history. The time series indicating the voltage history of battery cell C includes the voltage value detected in the previous cycle and the voltage value detected in the current cycle. In step S310, the battery monitoring circuit 120 may further use a pair of current sensing pins to detect the current of the battery pack 10. That is, the control circuit 140 may collect the analog signal indicating the current of the battery pack 10, convert the collected analog signal into a digital signal, and record it in the memory as the latest value in the time series indicating the current history.

[0081] In step S320, the control circuit 140, based on the multiple battery cells C1 to C2 of the first battery module 11 detected by the battery monitoring circuit 120, performs the following steps: m Multiple battery cells C of the second battery module 12 m+1 ~C m+n The voltage history of each battery cell in the busbar 13 is used to diagnose the problem.

[0082] refer to Figure 4According to the first embodiment, step S320 includes steps S410 to S470. In step S410, the control circuit 140 determines whether the battery pack 10 is kept in a discharge mode for a set time (e.g., 1 second) or more based on the current detected by the battery monitoring circuit 120. That is, the control circuit 140 records a historical time series indicating changes in the current of the battery pack 10 in a memory, and determines whether the battery pack 10 is being continuously discharged for a set time or more based on the recorded current time series. For example, if it is programmed to record the charging current of the battery pack 10 as a positive value and the discharging current as a negative value in the memory, when the time series of the current recorded in the time range from a set time earlier than the current time to the current time is recorded as a negative value, the control circuit 140 determines that the value of step S410 is "yes"; otherwise, it determines that the value of step S410 is "no". When the value of step S410 is "yes", step S420 is executed. When the value of step S410 is "no", step S470 is executed.

[0083] In step S420, the control circuit 140 determines the multiple battery cells C1 to C2 of the first battery module 11. m Multiple battery cells C of the second battery module 12 m+1 ~C m+n The average voltage. The average voltage in step S420 can be determined by the following equation 1 or 2.

[0084] Equation 1

[0085]

[0086] Equation 2

[0087]

[0088] In equations 1 and 2, t is the current time, and V... y [t] is the battery cell C detected by the battery monitoring device at the current time. y The voltage, and V AV [t] is the average voltage at the current time. Equation 2 differs from Equation 1 because the average voltage is calculated for both cell Cs, excluding the state dependent on busbar 13. m C m+1 voltage V m [t]、V m+1 It is calculated in the case of [t].

[0089] In step S430, the control circuit 140 determines (i) the battery cell C arranged at the upstream end of the first battery module 11. m voltage drop V m [t] and average pressure drop VAV The difference V between [t] AV [t]-V m [t] and (ii) are battery cells C arranged at the downstream end of the second battery module 12. m+1 voltage V m+1 [t] and average pressure drop V AV The difference V between [t] AV [t]-V m+1 [t] Are both greater than the reference voltage difference? When busbar 13 and multiple battery cells C1~C m+n When all conditions are normal, considering the 120-degree voltage divider capability of the battery monitoring circuit, the reference voltage difference (e.g., 0.3V) is preset to be greater than V. AV [t]-V m [t] and V AV [t]-V m+1 [t]. A value of "Yes" in step S430 indicates that the probability of busbar 13 being in a fault state is equal to or greater than the reference value. When the value of step S430 is "Yes", step S440 is executed. When the value of step S430 is "No", step S470 is executed.

[0090] In step S440, control circuit 140 increments the diagnostic count by a predetermined value (e.g., 1). The diagnostic count indicates the number of times the value in step S430 has been continuously determined to be "yes".

[0091] In step S450, control circuit 140 determines whether the diagnostic count is equal to or greater than a reference count (e.g., 3). When the value of step S450 is "yes", step S460 is executed.

[0092] In step S460, control circuit 140 sets a diagnostic flag indicating that busbar 13 is in a fault state. Control circuit 140 can perform a predetermined protection operation in response to the setting of the diagnostic flag. In one example, control circuit 140 can send a fault message indicating that busbar 13 is in a fault state to the upper-level controller 2. The upper-level controller 2 can stop the power conversion system 30 in response to the fault message. In another example, control circuit 140 can turn off relay 20. In yet another example, control circuit 140 can disconnect battery cell C. m C m+1 The detected voltage value V m [t]、V m+1 Each voltage value in [t] is set to be equal to multiple battery cells C1~C m+n Average voltage V AV [t].

[0093] In step S470, the control circuit 140 sets the diagnostic count to an initial value (e.g., 0) that is smaller than the reference count.

[0094] refer to Figure 5 According to the second embodiment, step S320 includes steps S510 to S550. In step S510, the control circuit 140 determines whether the battery pack 10 switches from a charging mode or a rest mode to a discharging mode based on the current detected by the battery monitoring circuit 120. The rest mode refers to a mode in which the relay 20 is turned off or the power conversion system 30 is stopped, and therefore neither the charging current nor the discharging current flows through the first battery module 11 and the second battery module 12. The charging mode refers to a mode in which power is supplied to the battery pack 10 from the power conversion system and the charging current flows through the first battery module 11 and the second battery module 12.

[0095] For example, control circuit 140 records a historical time series indicating changes in the current of battery pack 10 in a memory, and when, based on the recorded current time series, the current was recorded as 0 or positive from a diagnostic time earlier than the current time and the current was recorded as negative at the current time, control circuit 140 can determine that the value of step S510 is "yes". If not, the value of step S510 can be determined as "no". When the value of step S510 is "yes", step S520 is executed.

[0096] In step S520, the control circuit 140 determines the battery cell C located at the upstream end of the first battery module 11 within the diagnostic time. m The voltage drop, the battery cell C located at the downstream end of the second battery module 12 m+1 The voltage drop, and the multiple battery cells C1 to C1 of the first battery module 11 m Multiple battery cells C of the second battery module 12 m+1 ~C m+n The average pressure drop in step S520 can be determined by the following equations 3 or 4.

[0097] Equation 3

[0098]

[0099] Equation 4

[0100]

[0101] In equations 3 and 4, t is the current time, and ΔV y [t] represents the cell C of the battery. y The voltage drop, and ΔV AV [t] is the average pressure drop. ΔV y [t] equals Vy [tt D ]-V y [t], and t D This refers to the diagnosis time. That is, V y [tt D [This can be a single cell C detected during operation of the battery pack 10 in either idle or charging mode.] y The voltage, and V y [t] can be the first cell C detected after battery pack 10 switches from idle mode or charging mode to discharge mode. y The voltage.

[0102] Equation 4 differs from Equation 3 because the average voltage drop is based on the two cell C values ​​excluding the state dependent on busbar 13. m C m+1 pressure drop ΔV m [t]、ΔV m+1 It is calculated in the case of [t].

[0103] In step S530, the control circuit 140 determines the reference voltage drop by multiplying the change in current during the diagnostic time by a predetermined conversion factor. The change in current can be equal to I... P [tt D ]-IP[t]. I P [tt D [I] can be the current of the battery pack 10 detected during operation of the battery pack 10 in either idle or charging mode, and I P [t] can be the first current detected in battery pack 10 after it switches from idle mode or charging mode to discharging mode. The conversion factor can be a preset value that takes into account the internal resistance range of the individual battery cell C when it is in normal condition.

[0104] In step S540, the control circuit 140 determines (i) the battery cell C arranged at the upstream end of the first battery module 11. m pressure drop ΔV m [t] and average pressure drop ΔV AV The difference ΔV between [t] m [t]-ΔV AV [t] and (ii) are battery cells C arranged at the downstream end of the second battery module 12. m+1 pressure drop ΔV m+1 [t] and average pressure drop ΔV AV The difference ΔV between [t] m+1 [t]-ΔV AV[t] Are both greater than the reference voltage drop? A value of "Yes" in step S540 indicates that busbar 13 is in a fault state. If a value of "Yes" in step S540 is "Yes", then step S550 is executed.

[0105] In step S550, control circuit 140 sets a diagnostic flag indicating that busbar 13 is in a fault state. Control circuit 140 can perform a predetermined protection operation in response to the setting of the diagnostic flag. In one example, control circuit 140 can send a fault message indicating that busbar 13 is in a fault state to the upper-level controller 2. The upper-level controller 2 can then stop the power conversion system 30 in response to the fault message. In another example, control circuit 140 can turn off relay 20.

[0106] The embodiments of the present disclosure described above can be implemented not only by apparatus and methods, but also by a program that performs functions corresponding to the configuration of the embodiments of the present disclosure or a recording medium on which the program is recorded, and such implementation can be readily implemented by those skilled in the art from the disclosure of the embodiments described above.

[0107] Although the present disclosure has been described above with reference to a limited number of embodiments and accompanying drawings, the present disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes can be made thereto in terms of the technical aspects of the present disclosure and within the equivalent scope of the appended claims.

[0108] Additionally, since many substitutions, modifications and alterations can be made to the above-described disclosure by those skilled in the art without departing from the technical aspects of this disclosure, this disclosure is not limited to the above embodiments and drawings, and all or some of the embodiments can be selectively combined to allow for various modifications.

[0109] (Description of reference numerals in the attached diagram)

[0110] 1: Energy storage system

[0111] 10: Battery pack; 11, 12: Battery module; C: Individual battery cell

[0112] 20: Relay

[0113] 30: Power conversion system

[0114] 100: Busbar Diagnostic Device

[0115] 110: Voltage sensing channel; L: Voltage sensing line

[0116] 120: Battery monitoring circuit; P: Voltage sensing pin

[0117] 130: Bypass device

[0118] 140: Control Circuit

[0119] 150: Communication circuit

Claims

1. A busbar diagnostic device for a battery pack, the battery pack including a busbar connected between a positive terminal of a first battery module comprising a plurality of battery cells connected in series and a negative terminal of a second battery module comprising a plurality of battery cells connected in series, the busbar diagnostic device comprising: A battery monitoring circuit, comprising a plurality of voltage sensing pins, and configured to use the potential difference between every two adjacent voltage sensing pins to detect the voltage of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module. A voltage sensing channel, the voltage sensing channel comprising a plurality of voltage sensing lines that connect the positive and negative terminals of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module to the plurality of voltage sensing pins. A bypass unit is connected to the busbar via a first voltage sensing pin and a second voltage sensing pin among the plurality of voltage sensing pins. The first voltage sensing pin is connected to the positive terminal of the upstream battery cell of the first battery module via one of the plurality of voltage sensing lines, and the second voltage sensing pin is connected to the negative terminal of the downstream battery cell of the second battery module via another of the plurality of voltage sensing lines. A control circuit configured to diagnose the busbar based on the voltage of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module. The control circuit is configured as follows: When it is determined that the battery pack has been kept in discharge mode for a set time or longer, at each predetermined diagnostic time... Determine the average voltage of multiple battery cells in the first battery module and multiple battery cells in the second battery module. When both the difference between the voltage of the upstream battery cell in the first battery module and the average voltage, and the difference between the voltage of the downstream battery cell in the second battery module and the average voltage, are greater than a reference voltage difference, the diagnostic count is increased by a predetermined value. When the increased diagnostic count is equal to or greater than the reference count, a diagnostic flag indicating that the busbar is in a faulty state is set.

2. The busbar diagnostic device according to claim 1, wherein, The bypass unit includes a diode, and The anode and cathode of the diode are respectively connected to the first voltage sensing pin and the second voltage sensing pin.

3. The busbar diagnostic device according to claim 1, wherein, Each voltage sensing line includes a protective resistor with a predetermined resistance value.

4. The busbar diagnostic device according to claim 1, wherein, The battery monitoring circuit further includes a pair of current sensing pins connected to the current path of the battery pack, and is configured to use the potential difference between the pair of current sensing pins to detect the current flowing through the current path.

5. The busbar diagnostic device according to claim 1, wherein, The control circuit is configured to set the diagnostic count to an initial value smaller than the reference count when at least one of the difference between the voltage of the upstream battery cell of the first battery module and the average voltage and the difference between the voltage of the downstream battery cell of the second battery module and the average voltage is equal to or less than the reference voltage difference.

6. A busbar diagnostic device for a battery pack, the battery pack including a busbar connected between a positive terminal of a first battery module comprising a plurality of battery cells connected in series and a negative terminal of a second battery module comprising a plurality of battery cells connected in series, the busbar diagnostic device comprising: A battery monitoring circuit, comprising a plurality of voltage sensing pins, and configured to use the potential difference between every two adjacent voltage sensing pins to detect the voltage of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module. A voltage sensing channel, the voltage sensing channel comprising a plurality of voltage sensing lines that connect the positive and negative terminals of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module to the plurality of voltage sensing pins. A bypass unit is connected to the busbar via a first voltage sensing pin and a second voltage sensing pin among the plurality of voltage sensing pins. The first voltage sensing pin is connected to the positive terminal of the upstream battery cell of the first battery module via one of the plurality of voltage sensing lines, and the second voltage sensing pin is connected to the negative terminal of the downstream battery cell of the second battery module via another of the plurality of voltage sensing lines. A control circuit configured to diagnose the busbar based on the voltage of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module. The control circuit is configured as follows: When it is determined that the battery pack has switched from rest mode or charging mode to discharging mode. Determine the voltage drop of the upstream battery cell in the first battery module, the voltage drop of the downstream battery cell in the second battery module, and the average voltage drop of multiple battery cells in the first battery module and the second battery module during the diagnostic time. When both the difference between the voltage drop of the upstream battery cell in the first battery module and the average voltage drop, and the difference between the voltage drop of the downstream battery cell in the second battery module and the average voltage drop, are greater than the reference voltage drop, a diagnostic flag indicating that the busbar is in a fault state is set.

7. The busbar diagnostic device according to claim 6, wherein, The control circuit is configured to determine the reference voltage drop by multiplying the change in current during the diagnostic time by a predetermined conversion factor when it is determined that the battery pack has switched from a rest mode or a charging mode to a discharging mode.

8. A battery pack comprising a busbar diagnostic device according to any one of claims 1 to 7.

9. An energy storage system comprising a battery pack according to claim 8.

10. A busbar diagnostic method, the busbar diagnostic method being executable by a busbar diagnostic device according to any one of claims 1 to 7, the busbar diagnostic method comprising: The battery monitoring circuit uses the potential difference between every two adjacent voltage sensing pins of the plurality of voltage sensing pins to detect the voltage of each of the plurality of battery cells in the first battery module and the plurality of battery cells in the second battery module. as well as The control circuit diagnoses the busbar based on the voltage of each of the multiple battery cells in the first battery module and the multiple battery cells in the second battery module, as detected by the battery monitoring circuit.

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