Battery system and battery pack diagnosis method by supplementing cell voltage and cell temperature data

Abstract

The present invention relates to a battery system and a battery pack diagnosis method by supplementing cell voltage and cell temperature data. The battery system comprises: a battery pack including a plurality of battery cells; a cell monitoring controller (CMC) for monitoring a plurality of first cell voltages and a plurality of first cell temperatures of the plurality of battery cells; and a battery management system (BMS) which determines a wireless communication status with the CMC, and diagnoses the battery pack on the basis of the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC according to the wireless communication status with the CMC or diagnoses the battery pack by estimating a plurality of second cell voltages and a plurality of second cell temperatures of the plurality of battery cells.

Description

How to diagnose a battery pack by supplementing battery system and cell voltage and cell temperature data.

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0188920, filed December 21, 2023, and Korean Patent Application No. 10-2024-0052995, filed April 19, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present disclosure relates to a method for diagnosing a battery pack by supplementing battery system and cell voltage and cell temperature data.

[0004] The Battery Management System (BMS) can receive cell voltage and temperature values ​​from the Cell Monitoring Controller (CMC), which monitors the cell voltage and temperature of each of the multiple battery cells. The BMS and CMC can communicate wirelessly. However, if the wireless connection to the CMC is poor, the BMS cannot accurately determine the cell voltage and temperature, potentially causing the battery pack to shut down.

[0005] However, since battery utilization becomes unstable whenever communication with the CMC is unstable and power supply to the battery pack is interrupted, there is a need to supplement cell voltage and cell temperature data due to poor communication with the CMC to ensure stable power supply.

[0006] The present invention aims to provide a battery system capable of supplementing cell voltage and cell temperature data and a method for diagnosing a battery pack by supplementing cell voltage and cell temperature data when a BMS wirelessly connected to a CMC is unstable in the wireless connection with the CMC.

[0007] According to one aspect of the invention, a battery system includes a battery pack including a plurality of battery cells, a cell monitoring controller (CMC) that monitors a plurality of first cell voltages and a plurality of first cell temperatures of the plurality of battery cells, and a battery management system (BMS) that determines a wireless communication status with the CMC and diagnoses the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC, or estimates a plurality of second cell voltages and a plurality of second cell temperatures of the plurality of battery cells to diagnose the battery pack.

[0008] The BMS may include a main control unit (MCU) that derives a cell voltage deviation of each of the plurality of battery cells based on the pack voltage of the battery pack and stores the derived cell voltage deviation in a memory when wireless communication with the CMC is normal, and a diagnostic unit that diagnoses the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC when wireless communication with the CMC is normal.

[0009] The BMS further includes at least one input terminal electrically connected to at least one of the two terminals of the battery pack, and the MCU can determine a cell voltage deviation of each of the plurality of battery cells by subtracting each of the plurality of first cell voltages from a value obtained by dividing a pack voltage of the battery pack derived based on a pack voltage signal received from at least one of the two terminals of the battery pack by the number of the plurality of battery cells.

[0010] The BMS may further include a cell voltage estimation unit that determines, as the plurality of second cell voltages, a value obtained by dividing a pack voltage of the battery pack derived based on a pack voltage signal received from at least one of both ends of the battery pack by the number of the plurality of battery cells, and subtracting a cell voltage deviation stored in a normal state before the abnormal state of wireless communication with the CMC, when the wireless communication with the CMC is in an abnormal state.

[0011] The BMS may further include a cooling unit including an inlet into which the coolant is introduced and an outlet through which the coolant is discharged to cool the battery pack by heat exchange with the battery pack through coolant, a first temperature sensor for measuring the temperature of the inlet of the cooling unit, a second temperature sensor for measuring the temperature of the outlet of the cooling unit, and a current sensor for measuring the pack current of the battery pack, and the BMS may further include a first input terminal electrically connected to the first temperature sensor, a second input terminal electrically connected to the second temperature sensor, a third input terminal electrically connected to the current sensor, and a communication unit for receiving the plurality of first cell voltages and the plurality of first cell temperatures from the CMC through wireless communication.

[0012] The memory has a lookup table pre-stored to indicate cell temperature values ​​according to the range of each pack current and coolant temperature through a pack test for the battery pack, and the BMS further includes a cell temperature estimation unit that calculates the temperature of the coolant from the temperature of the inlet and the temperature of the outlet when the wireless communication with the CMC is in an abnormal state, and derives the plurality of second cell temperatures based on the temperature of the coolant, the pack current, and the lookup table, and the diagnostic unit can diagnose the battery pack based on the plurality of second cell voltages and the plurality of second cell temperatures when the wireless communication with the CMC is in an abnormal state.

[0013] According to another aspect of the invention, a method is provided for diagnosing a battery pack, wherein a battery system includes a battery pack including a plurality of battery cells, a cell monitoring controller (CMC) for monitoring a plurality of first cell voltages and a plurality of first cell temperatures of the plurality of battery cells, and a battery management system (BMS) for diagnosing the battery pack, the method comprising: a step of determining a wireless communication status with the CMC; and a step of diagnosing the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC, or estimating a plurality of second cell voltages and a plurality of second cell temperatures of the plurality of battery cells, according to the wireless communication status with the CMC.

[0014] The method may further include a step of deriving a cell voltage deviation of each of the plurality of battery cells based on the pack voltage of the battery pack and storing the same in a memory when the wireless communication with the CMC is normal, and a step of diagnosing the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC when the wireless communication with the CMC is normal.

[0015] The BMS may further include at least one input terminal electrically connected to at least one of the two terminals of the battery pack, and may further include a step of determining a cell voltage deviation of each of the plurality of battery cells by subtracting each of the plurality of first cell voltages from a value obtained by dividing a pack voltage of the battery pack derived based on a pack voltage signal received from at least one of the two terminals of the battery pack by the number of the plurality of battery cells.

[0016] In a case where the wireless communication with the CMC is in an abnormal state, the method may further include a step of deriving a pack voltage of the battery pack based on a pack voltage signal received from at least one of the two ends of the battery pack, and a step of determining a value obtained by dividing the pack voltage of the battery pack by the number of the plurality of battery cells and subtracting a cell voltage deviation stored in a normal state before the abnormal state of the wireless communication with the CMC as the plurality of second cell voltages.

[0017] The method may further include a step of receiving a signal indicating the temperature of an inlet of a cooling unit including an inlet into which the coolant is introduced and an outlet through which the coolant is discharged, by a first input terminal electrically connected to a first temperature sensor for measuring the temperature of the inlet of the cooling unit to cool the battery pack by heat exchange with the battery pack through coolant, a step of receiving a signal indicating the temperature of the inlet, a step of receiving a signal indicating the temperature of the outlet, by a second input terminal electrically connected to a second temperature sensor for measuring the temperature of the outlet of the cooling unit, a step of receiving a signal indicating the temperature of the outlet, by a third input terminal electrically connected to a current sensor for measuring pack current of the battery pack, and a step of receiving the plurality of first cell voltages and the plurality of first cell temperatures from the CMC through wireless communication.

[0018] The memory may further include a step of pre-stored a lookup table indicating cell temperature values ​​according to the range of each pack current and coolant temperature through a pack test for the battery pack, a step of calculating the temperature of the coolant from the temperature of the inlet and the temperature of the outlet when the wireless communication with the CMC is in an abnormal state, a step of deriving the plurality of second cell temperatures based on the temperature of the coolant, the pack current, and the lookup table, and a step of diagnosing the battery pack based on the plurality of second cell voltages and the plurality of second cell temperatures when the wireless communication with the CMC is in an abnormal state.

[0019] According to the present invention, the BMS receives cell temperature and cell voltage information of the battery from the CMC, but even if the wireless connection with the CMC is unstable, the BMS continuously monitors the cell voltage and cell temperature so that the power supply of the battery pack is not immediately interrupted due to the instability of the wireless connection, and the battery power can be stably supplied to a vehicle, etc.

[0020] According to the present invention, it is possible to design a battery system that is more robust in terms of safety by continuously monitoring cell voltage and cell temperature.

[0021] Coolant, which cools a battery pack comprising multiple battery cells, cools the temperature of the battery through heat exchange with the battery, so there can be a correlation between the temperature of the coolant and the cell temperatures of the battery cells. According to the present invention, the accuracy of cell temperature estimation can be improved by utilizing a lookup table indicating the correlation between the temperature of the coolant and the cell temperatures of the battery cells.

[0022] FIG. 1 is a block diagram schematically illustrating a battery system according to one embodiment.

[0023] Figure 2 is a block diagram schematically illustrating the configuration of the battery pack illustrated in Figure 1.

[0024] Figure 3 is a flowchart of a battery pack diagnosis method according to one embodiment.

[0025] FIG. 4 is a table showing an example for explaining an operation of a BMS estimating the cell voltage of each of a plurality of battery cells according to one embodiment.

[0026] Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the attached drawings. The same or similar components will be given the same or similar drawing reference numerals, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "part" used for components in the following description are given or used interchangeably only for the convenience of writing the specification, and do not in themselves have distinct meanings or roles. In addition, when describing the embodiments disclosed in this specification, if it is determined that a specific description of a related known technology may obscure the gist of the embodiments disclosed in this specification, a detailed description thereof will be omitted. In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention.

[0027] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0028] In this application, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0029] Among the configurations according to one embodiment, a configuration that controls another configuration under specific control conditions may be installed with a program implemented as a set of commands that embody the control algorithms necessary to control the other configuration. The control configuration may process input data and stored data according to the installed program to generate output data. The control configuration may include non-volatile memory for storing the program and memory for storing data.

[0030] FIG. 1 is a block diagram schematically illustrating a battery system according to one embodiment.

[0031] Referring to FIG. 1, the battery system (1) may include a battery pack (10), a cooling unit (20), two temperature sensors (30, 31), a current sensor (40), a cell monitoring controller (CMC) (50), a battery management system (BMS) (60), and a relay (70, 71).

[0032] One end of the relay (70, 71) is connected to the battery pack (10), and the other end of the relay (70, 71) is connected to at least one component in an external device (2). Closing and opening of the relay (70, 71) can be controlled according to a relay control signal (RCS1, RCS2) supplied from the BMS (60).

[0033] The battery system (1) can be connected to an external device (2). The external device (2) can include a load and a charging device such as an inverter or a converter. If the external device (2) is a charger, both ends (P+, P-) of the battery system (1) are connected to the charger so that power can be supplied from the charger and charged. If the external device (2) is a load, both ends (P+, P-) of the battery system (1) are connected to the load so that power supplied by the battery pack (10) can be discharged through the load.

[0034] The battery pack (10) may include a plurality of battery cells.

[0035] The cooling unit (20) can cool the battery pack (10) by heat exchange with the battery pack (10) through coolant. The cooling unit (20) can include an inlet (201) and an outlet (202). The inlet (201) can be an area where coolant is introduced into the cooling unit (20). The outlet (202) can be an area where coolant is discharged from the cooling unit (20). The cooling unit (20) can prevent performance degradation of the battery pack (10) by cooling the battery pack (10) to a predetermined degree through heat exchange with the battery pack (10).

[0036] The temperature sensor (30) can measure the temperature of the inlet (201). The temperature sensor (30) can generate a signal indicating the temperature of the inlet (201) and transmit it to the BMS (60). The temperature sensor (31) can measure the temperature of the outlet (202). The temperature sensor (31) can generate a signal indicating the temperature of the outlet (202) and transmit it to the BMS (60).

[0037] The current sensor (40) is connected to one end of the battery pack (10) and can measure the current flowing in one end of the battery pack (10). The current sensor (40) can generate a signal indicating the pack current of the battery pack (10) and transmit it to the BMS (60). The current sensor (40) can be located on a high voltage line connected from the battery pack (10) to both ends (P+, P-) of the battery system (1). The current sensor (40) can be implemented as a resistance detection type that detects current using resistance or a magnetic field detection type that detects a magnetic field.

[0038] The CMC (50) can monitor multiple cell voltages and multiple cell temperatures of multiple battery cells (hereinafter referred to as “multiple battery cells”) included in the battery pack (10). For example, the CMC (50) can derive the cell voltage of each of the multiple battery cells based on a signal representing the voltage across each of the multiple battery cells.

[0039] Figure 2 is a block diagram schematically illustrating the configuration of the battery pack illustrated in Figure 1.

[0040] Referring to FIG. 2, the battery pack (10) may include a plurality of battery modules (110, 120, 130) and a plurality of temperature sensors (111, 112, 121, 122, 131, 132).

[0041] A plurality of battery modules (110, 120, 130) may be connected in series. Each of the plurality of battery modules (110, 120, 130) (e.g., 110) may include a corresponding battery cell (1101_1-1101_n) among the plurality of battery cells (1101_1-1101_n, 1201_1-1201_n, 1301_1-1301_n). The plurality of battery cells (1101_1-1101_n, 1201_1-1201_n, 1301_1-1301_n) may be connected in series. Here, n is a natural number greater than or equal to 3.

[0042] In Fig. 2, the battery pack (10) includes a plurality of battery cells (1101_1-1101_n, 1201_1-1201_n, 1301_1-1301_n) connected in series, and the number of the plurality of battery modules (110, 120, 130) is illustrated as three, but this is for convenience of explanation and the invention is not limited thereto. The battery pack (10) may include two or more battery modules, and each battery module may include two or more battery cells connected in series, two or more battery cells connected in parallel, a plurality of battery cells connected in series, or two or more battery cells connected in parallel.

[0043] Two temperature sensors (111, 112) may be positioned adjacent to the battery module (110), two temperature sensors (121, 122) may be positioned adjacent to the battery module (120), and two temperature sensors (131, 132) may be positioned adjacent to the battery module (130).

[0044] In FIG. 2, two (e.g., 111, 112) of the plurality of temperature sensors (111, 112, 121, 122, 131, 132) are positioned adjacent to each of the plurality of battery modules (110, 120, 130) (e.g., 110), but this is for convenience of explanation and the invention is not limited thereto. One or more temperature sensors may be positioned adjacent to each of the plurality of battery modules (110, 120, 130).

[0045] Each of the plurality of temperature sensors (111, 112, 121, 122, 131, 132) (e.g., 111) can measure the temperature of a point where each temperature sensor (e.g., 111) is located and generate a corresponding temperature measurement signal (e.g., TS1) among the plurality of temperature measurement signals (TS1-TS6). The plurality of temperature sensors (111, 112, 121, 122, 131, 132) can transmit the plurality of temperature measurement signals (TS1-TS6) to the CMC (50).

[0046] Since each temperature sensor is located adjacent to the battery module, each temperature sensor can be located adjacent to each of the multiple battery cells constituting the battery module. In other words, the temperature measured by each temperature sensor can be similar to the temperature of each of the multiple battery cells.

[0047] The CMC (50) can receive a plurality of temperature measurement signals (TS1-TS6) from a plurality of temperature sensors (111, 112, 121, 122, 131, 132) provided in the battery pack (10). Based on the measurement values ​​of the plurality of temperature measurement signals (TS1-TS6) received from the plurality of temperature sensors (111, 112, 121, 122, 131, 132), the CMC (50) can determine a representative value for at least one battery cell (e.g., 1101_1-1101_n) corresponding to each of the plurality of temperature sensors (TS1-TS6) (e.g., TS1) among the plurality of battery cells (1101_1-1101_n, 1201_1-1201_n, 1301_1-1301_n).

[0048] In the example of FIG. 2, the CMC (50) can determine two representative values ​​representing the cell temperature of each of the plurality of battery cells (1101_1-1101_n) using the measurement values ​​of two temperature measurement signals (TS1, TS2) received from two temperature sensors (111, 112) positioned adjacent to the battery module (110). The CMC (50) can determine two representative values ​​representing the cell temperature of each of the plurality of battery cells (1201_1-1201_n) using the measurement values ​​of two temperature measurement signals (TS3, TS4) received from two temperature sensors (121, 122) positioned adjacent to the battery module (120). The CMC (50) can determine two representative values ​​representing the cell temperature of each of the plurality of battery cells (1301_1-1301_n) by using the measurement values ​​of two temperature measurement signals (TS5, TS6) received from two temperature sensors (131, 132) located adjacent to the battery module (130).

[0049] For example, when n is 10 in FIG. 2, the CMC (50) can use the measurement value of the temperature measurement signal (TS1) to determine a representative value representing the cell temperature of each of the battery cells (e.g., 1101-1105) corresponding to the temperature sensor (111) among the plurality of battery cells (1101_1-1101_10). In addition, the CMC (50) can use the measurement value of the temperature measurement signal (TS2) to determine a representative value representing the cell temperature of each of the battery cells (e.g., 1106-1110) corresponding to the temperature sensor (112) among the plurality of battery cells (1101_1-1101_10).

[0050] Hereinafter, for convenience of explanation, each representative value of the cell temperature of each of the plurality of battery cells is referred to as a “cell temperature.” The CMC (50) can transmit representative values ​​(hereinafter, “multiple cell temperatures”) corresponding to the plurality of temperature sensors (111, 112, 121, 122, 131, 132) determined using the plurality of temperature measurement signals (TS1-TS6) to the BMS (60).

[0051] Referring back to FIG. 1, in FIG. 1, the CMC (50) is illustrated as monitoring multiple cell voltages and multiple cell temperatures of multiple battery cells, but this is for convenience of explanation and the invention is not limited thereto. In some embodiments, the battery system (1) includes a battery monitoring integrated circuit (BMIC), and the description of the CMC (50) described below can be equally applied to the BMIC.

[0052] The CMC (50) can generate signals indicating multiple cell voltages and multiple cell temperatures of multiple battery cells and transmit them to the BMS (60). In FIG. 1, the number of CMCs (50) is illustrated as one, but this is only for convenience of explanation, and the invention is not limited thereto. In some embodiments, the battery system (1) may include two or more CMCs.

[0053] The BMS (60) can receive signals indicating multiple cell voltages and multiple cell temperatures of multiple battery cells from the CMC (50) via wireless communication. The BMS (60) determines the wireless communication status with the CMC (50), and diagnoses the battery pack (10) based on the multiple first cell voltages and multiple first cell temperatures received from the CMC (50) according to the wireless communication status with the CMC (50), or can diagnose the battery pack (10) by estimating multiple second cell voltages and multiple second cell temperatures of the multiple battery cells. The BMS (60) can determine a power limit of the battery pack (10) based on the multiple first cell voltages and multiple first cell temperatures, or based on the multiple second cell voltages and multiple second cell temperatures.

[0054] The plurality of first cell voltages may represent a plurality of cell voltages received by the BMS (60) from the CMC (50), and the plurality of second cell voltages may represent cell voltage information estimated by the BMS (60) corresponding to the plurality of first cell voltages. The plurality of first cell temperatures may represent a plurality of cell temperatures received by the BMS (60) from the CMC (50), and the plurality of second cell temperatures may represent cell temperature information estimated by the BMS (60) corresponding to the plurality of first cell temperatures.

[0055] The power limit of the battery pack (10) may include a discharge power limit of the battery pack (10) and / or a charge power limit of the battery pack (10). The discharge power limit may be an amount of power that can be continuously expected from the battery pack (10) without exceeding the maximum allowable discharge current of the battery pack (10) for a predetermined period of time. The charge power limit may be an amount of power that can be continuously supplied to the battery pack (10) without exceeding the maximum allowable charge current of the battery pack (10) for a predetermined period of time.

[0056] The BMS (60) may include a plurality of input terminals (P1-P4). The input terminal (P1) may be electrically connected to a temperature sensor (30) and may receive a signal indicating the temperature of the inlet (201) from the temperature sensor (30). The input terminal (P2) may be electrically connected to a temperature sensor (31) and may receive a signal indicating the temperature of the outlet (202) from the temperature sensor (31). The input terminal (P3) may be electrically connected to at least one of the opposite terminals of the battery pack (10) and may receive a signal indicating the voltage of at least one of the opposite terminals of the battery pack (10). The input terminal (P3) may be implemented as at least one input terminal that receives each signal indicating the voltage of at least one of the opposite terminals of the battery pack (10). The MCU (630) may derive the pack voltage of the battery pack (10) based on the signal indicating the voltage of at least one of the opposite terminals of the battery pack (10). The input terminal (P4) is electrically connected to a current sensor (40) and can receive a signal indicating the pack current of the battery pack (10).

[0057] The BMS (60) may include a communication unit (610), a memory (620), a main control unit (MCU, Main Control Unit) (630), a cell voltage estimation unit (640), a cell temperature estimation unit (650), and a diagnostic unit (660).

[0058] The communication unit (610) can wirelessly communicate with the CMC (50) and receive signals indicating multiple cell voltages and multiple cell temperatures of multiple battery cells from the CMC (50). The communication unit (610) can transmit the signals indicating multiple cell voltages and multiple cell temperatures of multiple battery cells received from the CMC (50) to the MCU (630).

[0059] The MCU (630) can determine whether the wireless communication with the CMC (50) is normal. For example, if there is an error in the data received by the communication unit (610), if there is an error in the communication status check bit included in the data received by the communication unit (610), or if the IP, time, etc. of each frame received by the communication unit (610) are not updated, the MCU (630) can determine that the wireless communication with the CMC (50) is not normal but is in an abnormal state.

[0060] When the wireless communication with the CMC (50) is judged to be normal, the MCU (630) can derive the cell voltage deviation (621) of each of the plurality of battery cells based on the signal received from the CMC (50) by the communication unit (610) and the pack voltage of the battery pack (10), store the derived cell voltage deviation (621) in the memory (620), and transmit signals indicating the plurality of cell voltages and the plurality of cell temperatures of the plurality of battery cells indicated by the signal received from the CMC (50) to the diagnosis unit (660).

[0061] The MCU (630) may determine the cell voltage deviation (621) of each of the plurality of battery cells by subtracting the value obtained by dividing the pack voltage of the battery pack (10) derived by the MCU (630) by the number of battery cells based on the signal received from the input terminal (P3) by the value of each of the plurality of cell voltages of the plurality of battery cells received from the CMC (50). Hereinafter, the number of the plurality of battery cells may be stored in advance in the memory (620).

[0062] If the wireless communication with the CMC (50) is determined to be normal, the diagnostic unit (660) can diagnose the battery pack (10) based on the plurality of cell voltages and the plurality of cell temperatures of the plurality of battery cells received from the CMC (50). For example, the diagnostic unit (660) can diagnose the battery pack (10) as being in an abnormal state if at least one of the plurality of cell voltages is outside the normal operating range of the battery cell, and / or at least one of the plurality of cell temperatures exceeds the normal temperature threshold value of the battery cell.

[0063] For example, if it is determined that the plurality of cell voltages and the plurality of cell temperatures of the plurality of battery cells are within the normal operating range of the battery pack (10), the diagnostic unit (660) can maintain the power of the battery pack (10) as before. If it is determined that the plurality of cell voltages and the plurality of cell temperatures of the plurality of battery cells are outside the normal operating range of the battery pack (10), the diagnostic unit (660) can calculate the power limit value of the battery pack (10) according to the plurality of cell voltages and the plurality of cell temperatures of the plurality of battery cells.

[0064] The diagnostic unit (660) can transmit cell information on multiple battery cells to the electronic control unit (ECU) of the vehicle. The diagnostic unit (660) can transmit the cell information to the ECU of the vehicle, for example, via CAN communication. The cell information may be multiple cell voltages and multiple cell temperatures of multiple battery cells based on signals received from the CMC (50), or may be estimated cell voltages and estimated cell temperatures of each of the multiple battery cells received from the cell voltage estimation unit (640) and the cell temperature estimation unit (650).

[0065] When the wireless communication with the CMC (50) is determined to be normal, the MCU (630) can derive the cell voltage deviation (621) and store it in the memory (620). For example, the MCU (630) can derive the cell voltage deviation (621) at a predetermined cycle and store it in the memory (620). Here, the predetermined cycle may be a cycle according to a cycle in which the communication unit (610) receives signals indicating multiple cell voltages and multiple cell temperatures of multiple battery cells from the CMC (50). The cell voltage deviation (621) stored in the memory (620) may be updated with the latest cell voltage deviation among the multiple cell voltage deviations derived from the MCU (630). The memory (620) may store the cell voltage deviation (621) derived from the MCU (630).

[0066] A lookup table (622) may be stored in the memory (620). The lookup table (622) may indicate cell temperature values ​​according to the ranges of pack current and coolant temperature of the cooling unit (20) through a pack test for the battery pack (10). Here, the coolant temperature may be the difference between the temperature of the inlet (201) and the temperature of the outlet (202). Here, the cell temperature values ​​may be temperature values ​​corresponding to a plurality of temperature sensors (111, 112, 121, 122, 131, 132) illustrated in FIG. 2. The MCU (630) may calculate the coolant temperature based on the temperature of the inlet (201) received through the input terminal (P1) and the temperature of the outlet (202) received through the input terminal (P2).

[0067] The lookup table may be generated through a pack test for the battery pack (10). Here, the pack test may be a test that flows a predetermined pack current to the battery pack (10) and measures each of the cell temperatures of the plurality of battery cells according to each coolant temperature. For example, according to a first pack test, a first lookup table between the pack current and the cell temperature is generated, and according to a second pack test, a second lookup table between the pack current and the coolant temperature (e.g., the difference between the temperature of the inlet (201) and the temperature of the outlet (202)) is generated, and a final lookup table indicating cell temperature data according to each range of the pack current and the coolant temperature may be generated based on the first lookup table and the second lookup table. In one embodiment, the lookup table (622) may be the final lookup table here.

[0068] For example, each row of the lookup table may correspond to a current range in which the pack current is divided into a predetermined number of sections, and each column of the lookup table may correspond to a temperature range in which the temperature of the coolant, which represents the difference between the temperature of the inlet (201) and the temperature of the outlet (202), is divided into a predetermined number of sections. The data included in the lookup table may include cell temperature values ​​corresponding to each row and each column.

[0069] If the wireless communication with the CMC (50) is determined to be in an abnormal state, the MCU (630) can transmit the pack voltage of the battery pack (10) derived from the signal received through the input terminal (P3) to the cell voltage estimation unit (640). The cell voltage estimation unit (640) can determine the estimated cell voltage of each of the plurality of battery cells by subtracting the cell voltage deviation (621) of each of the plurality of battery cells from the value obtained by dividing the pack voltage of the battery pack (10) by the number of the plurality of battery cells. Here, the cell voltage deviation (621) of each of the plurality of battery cells may be the cell voltage deviation stored in the memory (620) in the normal state before the abnormal state of the wireless communication with the CMC (50). The cell voltage estimation unit (640) can transmit the estimated cell voltage of each of the plurality of battery cells to the diagnosis unit (660).

[0070] When the wireless communication with the CMC (50) is judged to be abnormal, the MCU (630) calculates the coolant temperature of the cooling unit (20) based on the temperature of the inlet (201) and the temperature of the outlet (202) derived from the signal received through the input terminals (P1, P2), derives the pack current of the battery pack (10) based on the pack current of the battery pack (10) received through the input terminal (P4), and transmits the coolant temperature and the pack current to the cell temperature estimation unit (650). The cell temperature estimation unit (650) can extract a target cell temperature value corresponding to the coolant temperature and the pack current received from the MCU (630) from the lookup table (622). The cell temperature estimation unit (650) can determine the extracted target cell temperature value as an estimated cell temperature and transmit it to the diagnosis unit (660).

[0071] If wireless communication with the CMC (50) is determined to be abnormal, the diagnostic unit (660) can diagnose the battery pack (10) based on the estimated cell voltage received from the cell voltage estimation unit (640) and the estimated cell temperature received from the cell temperature estimation unit (650).

[0072] Figure 3 is a flowchart of a battery pack diagnosis method according to one embodiment.

[0073] Hereinafter, descriptions of each component of the battery system (1) that overlap with the descriptions above may be omitted.

[0074] Referring to FIG. 3, a lookup table (622) may be stored in memory (620) (S100).

[0075] The BMS (60) can receive multiple cell voltages and multiple cell temperatures of multiple battery cells from the CMC (50) (S101).

[0076] BMS (60) can determine whether wireless communication with CMC (50) is normal (S102).

[0077] If the wireless communication with the CMC (50) is normal at step S102, the BMS (60) can calculate the cell voltage deviation of each of the plurality of battery cells by subtracting each of the plurality of cell voltages of each of the plurality of battery cells received from the CMC (50) from the value obtained by dividing the pack voltage of the battery pack (10) derived from the voltage measurement signal received from both ends of the battery pack (10) through the input terminal (P3) by the number of battery cells, and store the calculated cell voltage deviation of each of the plurality of battery cells in the memory (620) (S103).

[0078] Following step S103, the BMS (60) can diagnose the battery pack (10) based on multiple cell voltages and multiple cell temperatures of multiple battery cells received from the CMC (50) (S104).

[0079] If the wireless communication with the CMC (50) is abnormal at step S102, the BMS (60) can derive the pack voltage of the battery pack (10) from the voltage measurement signal received from both ends of the battery pack (10) through the input terminal (P3) (S105).

[0080] Following step S105, the BMS (60) can determine a plurality of estimated cell voltages of the plurality of battery cells based on the derived pack voltage and the cell voltage deviation (621) of each of the plurality of battery cells stored in the memory (620) (S106). Here, the cell voltage deviation (621) stored in the memory (620) may be a value stored in a normal state before an abnormal state of wireless communication with the CMC (50). The BMS (60) can determine a value obtained by subtracting the cell voltage deviation (621) of each of the plurality of battery cells stored in the memory (620) from a value obtained by dividing the pack voltage derived in step S105 by the number of the plurality of battery cells as the estimated cell voltage of each of the plurality of battery packs.

[0081] In addition, if the wireless communication with the CMC (50) is abnormal at step S102, the BMS (60) can receive signals indicating the pack current of the battery pack (10) from the current sensor (40), the temperature of the inlet (201) from the temperature sensor (30), and the temperature of the outlet (202) from the temperature sensor (31) (S107).

[0082] Following step S107, the BMS (60) can determine multiple estimated cell temperatures of multiple battery cells based on the pack current, the temperature difference between the inlet and outlet, and the lookup table (S108).

[0083] Following steps S106 and S108, the BMS (60) can diagnose the battery pack (10) based on a plurality of estimated cell voltages and a plurality of estimated cell temperatures of a plurality of estimated battery cells (S109).

[0084] Following step S109, the BMS (60) can calculate the power limit value of the battery pack (10) based on the cell voltage and cell temperature derived from the signal received from the CMC (50) in step S104, or based on the cell voltage and cell temperature estimated in step S109 (S110).

[0085] FIG. 4 is a table showing an example for explaining an operation of a BMS estimating the cell voltage of each of a plurality of battery cells according to one embodiment.

[0086] Referring to FIG. 4, steps S201 to S203 can explain the operation of the BMS (60) when the BMS (60) determines that wireless communication with the CMC (50) is normal.

[0087] Hereinafter, referring to FIG. 4, the plurality of battery cells included in the battery pack (10) are described as first to sixth battery cells (C1-C6).

[0088] If the communication with the CMC (50) is judged to be normal, the BMS (60) can derive the cell voltage (V1) by dividing the pack voltage (V_pack1) of the battery pack (10) derived from the voltage measurement signal received from both ends of the battery pack (10) through the input terminal (P3) by the number of battery cells (S201). Here, the pack voltage (V_pack1) of the battery pack (10) may be 24 V, and the number of battery cells may be 6. Each of the cell voltages (V1) derived by the BMS (60) for the first to sixth battery cells (C1-C6) in step S201 is 24 / 6=4 (V).

[0089] The BMS (60) can derive the cell voltage (V_cell) of each of the first to sixth battery cells (C1-C6) from the signal representing the cell voltage of each of the plurality of battery cells received from the CMC (50) (S202). In step S202, the cell voltages (V_cell) derived from the signal representing the cell voltage received by the BMS (60) from the CMC (50) for the first to sixth battery cells (C1-C6) are, in order from the first battery cell (C1), 3.998 V, 4 V, 3.997 V, 4.002 V, 4.003 V, and 4 V.

[0090] The BMS (60) can derive the cell voltage deviation (V_delta) by subtracting the corresponding cell voltage among the cell voltages (V_cell) derived in step S202 from each cell voltage (V1) derived in step S201 (S203). The cell voltage deviation (V_delta) obtained by subtracting V_cell from V1 by the BMS (60) for the first battery cell (C1) in step S203 is 4-3.998=0.002 (V). The cell voltage deviation (V_delta) obtained by subtracting V_cell from V1 by the BMS (60) for the second battery cell (C2) in step S203 is 4-4=0 (V). The cell voltage deviation (V_delta) obtained by subtracting V_cell from V1 by the BMS (60) for the third battery cell (C3) in step S203 is 4-3.997=0.003 (V). At step S203, the cell voltage deviation (V_delta) obtained by subtracting V_cell from V1 for the fourth battery cell (C4) by the BMS (60) is 4-4.002=-0.002 (V). At step S203, the cell voltage deviation (V_delta) obtained by subtracting V_cell from V1 for the fifth battery cell (C5) by the BMS (60) is 4-4.003=-0.003 (V). At step S203, the cell voltage deviation (V_delta) obtained by subtracting V_cell from V1 for the sixth battery cell (C6) by the BMS (60) is 4-4=0 (V).

[0091] In step S203, the BMS (60) can store the cell voltage deviation (V_delta) derived for each of the first to sixth battery cells (C1-C6) in the memory (620).

[0092] In step S204, the BMS (60) may determine that wireless communication with the CMC (50) is in an abnormal state. Referring to FIG. 4, steps S205 and S206 may explain the operation of the BMS (60) when the BMS (60) determines that wireless communication with the CMC (50) is in an abnormal state.

[0093] If the communication with the CMC (50) is judged to be abnormal, the BMS (60) can derive the cell voltage (V2) by dividing the pack voltage (V_pack2) of the battery pack (10) derived from the voltage measurement signal received from both ends of the battery pack (10) through the input terminal (P3) by the number of battery cells (S205). Here, the pack voltage (V_pack2) of the battery pack (10) may be 23.4 V, and the number of battery cells may be 6. In step S206, each of the cell voltages (V2) derived by the BMS (60) for the first to sixth battery cells (C1-C6) is 23.4 / 6=3.9 (V).

[0094] Since the communication with the CMC (50) is in an abnormal state, the BMS (60) can derive the estimated cell voltage (V_cell_EST) by subtracting the cell voltage deviation (V_delta) of the corresponding battery cell from the cell voltage deviation (V_delta) stored in the memory (620) from each cell voltage (V2) derived in step S205 (S206). The estimated cell voltage (V_cell_EST) obtained by subtracting the cell voltage deviation (V_delta) from V2 for the first battery cell (C1) in step S206 by the BMS (60) is 3.9-0.002=3.898 (V). The estimated cell voltage (V_cell_EST) obtained by subtracting the cell voltage deviation (V_delta) from V2 for the second battery cell (C2) in step S206 by the BMS (60) is 3.9-0=3.9 (V). At step S206, the estimated cell voltage (V_cell_EST) obtained by subtracting the cell voltage deviation (V_delta) from V2 for the third battery cell (C3) by the BMS (60) is 3.9-0.003=3.897(V). At step S207, the estimated cell voltage (V_cell_EST) obtained by subtracting the cell voltage deviation (V_delta) from V2 for the fourth battery cell (C4) by the BMS (60) is 3.9-(-0.002)=3.902(V). At step S207, the estimated cell voltage (V_cell_EST) obtained by subtracting the cell voltage deviation (V_delta) from V2 for the fifth battery cell (C5) by the BMS (60) is 3.9-(-0.003)=3.903(V). At step S207, the estimated cell voltage (V_cell_EST) obtained by subtracting the cell voltage deviation (V_delta) from V2 by the BMS (60) for the sixth battery cell (C6) is 3.9-0=3.9 (V).

[0095] In this way, the BMS (60) determines whether wireless communication with the CMC (50) is normal, and in the case of a normal state, diagnoses the battery pack (10) based on multiple cell voltages and multiple cell temperatures of multiple battery cells received from the CMC (50), and in the case of an abnormal state, estimates the cell voltage based on the pack voltage and the cell voltage deviation (621) stored in the memory (620) in the normal state, and estimates the cell temperature based on the pack current, coolant temperature, and a lookup table (622) previously stored in the memory (620), and diagnoses the battery pack (10) based on the estimated cell voltage and cell temperature.

[0096] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by a person having ordinary skill in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. A battery pack comprising a plurality of battery cells; A cell monitoring controller (CMC) that monitors a plurality of first cell voltages and a plurality of first cell temperatures of the plurality of battery cells; and A battery management system (BMS) that determines a wireless communication status with the CMC, and diagnoses the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC, or diagnoses the battery pack by estimating the plurality of second cell voltages and the plurality of second cell temperatures of the plurality of battery cells, depending on the wireless communication status with the CMC. A battery system comprising:

2. In paragraph 1, The above BMS, A main control unit (MCU) that derives the cell voltage deviation of each of the plurality of battery cells based on the pack voltage of the battery pack and stores it in memory when the wireless communication with the CMC is normal; and Including a diagnostic unit that diagnoses the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC when the wireless communication with the CMC is normal. Battery system.

3. In paragraph 2, The above BMS further comprising at least one input terminal electrically connected to at least one of the terminals of the battery pack; The above MCU, A value obtained by subtracting each of the plurality of first cell voltages from a value obtained by dividing the pack voltage of the battery pack derived based on a pack voltage signal received from at least one of the two ends of the battery pack by the number of the plurality of battery cells, is determined as the cell voltage deviation of each of the plurality of battery cells. Battery system.

4. In paragraph 1, The above BMS, In case the wireless communication with the CMC is in an abnormal state, the cell voltage estimation unit further includes a value obtained by dividing the pack voltage of the battery pack derived from a pack voltage signal received from at least one of the two ends of the battery pack by the number of the plurality of battery cells, and subtracting the cell voltage deviation stored in the normal state before the abnormal state of the wireless communication with the CMC, as the plurality of second cell voltages. Battery system.

5. In paragraph 1, A cooling unit including an inlet into which the cooling water is introduced and an outlet through which the cooling water is discharged, so as to cool the battery pack by heat exchange with the battery pack through the cooling water; A first temperature sensor for measuring the temperature of the inlet of the above cooling unit; a second temperature sensor for measuring the temperature of the outlet of the above cooling unit; and Further comprising a current sensor for measuring pack current of the battery pack; The above BMS, A first input terminal electrically connected to the first temperature sensor; A second input terminal electrically connected to the second temperature sensor; a third input terminal electrically connected to the above current sensor; and Further comprising a communication unit that receives the plurality of first cell voltages and the plurality of first cell temperatures via wireless communication from the CMC. Battery system.

6. In paragraph 5, In the memory, a lookup table is stored that indicates cell temperature values ​​according to the range of each pack current and coolant temperature through pack tests for the battery pack. The above BMS, If the wireless communication with the CMC is abnormal, the temperature of the coolant is calculated from the temperature of the inlet and the temperature of the outlet, and a cell temperature estimation unit is further included for deriving the plurality of second cell temperatures based on the temperature of the coolant, the pack current, and the lookup table. The above diagnostic section, If the wireless communication with the CMC is abnormal, the battery pack is diagnosed based on the plurality of second cell voltages and the plurality of second cell temperatures. Battery system.

7. A battery system including a battery pack including a plurality of battery cells, a cell monitoring controller (CMC) for monitoring a plurality of first cell voltages and a plurality of first cell temperatures of the plurality of battery cells, and a battery management system (BMS) for diagnosing the battery pack, in a method for diagnosing the battery pack, A step of determining the wireless communication status with the above CMC; and A step of diagnosing the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC, or diagnosing the battery pack by estimating the plurality of second cell voltages and the plurality of second cell temperatures of the plurality of battery cells, according to a wireless communication status with the CMC. method.

8. In paragraph 7, A step of deriving a cell voltage deviation of each of the plurality of battery cells based on the pack voltage of the battery pack and storing the same in memory when the wireless communication with the CMC is normal; and Further comprising a step of diagnosing the battery pack based on the plurality of first cell voltages and the plurality of first cell temperatures received from the CMC when the wireless communication with the CMC is normal. method.

9. In paragraph 8, The above BMS further comprising at least one input terminal electrically connected to at least one of the terminals of the battery pack; A step of further comprising determining a cell voltage deviation of each of the plurality of battery cells by subtracting each of the plurality of first cell voltages from a value obtained by dividing a pack voltage of the battery pack derived based on a pack voltage signal received from at least one of the two ends of the battery pack by the number of the plurality of battery cells, method.

10. In paragraph 7, If wireless communication with the above CMC is abnormal, A step of deriving a pack voltage of the battery pack based on a pack voltage signal received from at least one of the two terminals of the battery pack; and Further comprising a step of determining the plurality of second cell voltages as a value obtained by dividing the pack voltage of the battery pack by the number of the plurality of battery cells and subtracting the stored cell voltage deviation in the normal state before the abnormal state of wireless communication with the CMC. method.

11. In paragraph 7, A step for receiving a signal indicating the temperature of an inlet of a cooling unit including an inlet into which the coolant is introduced and an outlet through which the coolant is discharged, by a first temperature sensor electrically connected to a first input terminal, so as to cool the battery pack by heat exchange with the battery pack through coolant; A step for receiving a signal indicating the temperature of the outlet by a second input terminal electrically connected to a second temperature sensor measuring the temperature of the outlet of the cooling unit; A step for receiving a signal indicating the pack current from a third input terminal electrically connected to a current sensor measuring the pack current of the battery pack; and Further comprising a step of receiving said plurality of first cell voltages and said plurality of first cell temperatures via wireless communication from said CMC. method.

12. In paragraph 11, In the memory, a lookup table is stored that indicates cell temperature values ​​according to the range of each pack current and coolant temperature through pack tests for the battery pack. If wireless communication with the above CMC is abnormal, A step of calculating the temperature of the cooling water from the temperature of the inlet and the temperature of the outlet; A step of deriving the plurality of second cell temperatures based on the temperature of the coolant, the pack current, and the lookup table; and If the wireless communication with the CMC is abnormal, further comprising a step of diagnosing the battery pack based on the plurality of second cell voltages and the plurality of second cell temperatures. method.

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