Diagnostic method for battery management systems, battery devices, and cell voltage measurement lines

Abstract

In a battery management system, a battery monitoring circuit is connected to the battery cell via a cell voltage measurement line. With cell balancing disabled, the battery cell voltage is measured as a first voltage via the cell voltage measurement line, and with cell balancing enabled, the battery cell voltage is measured as a second voltage via the cell voltage measurement line. The processor diagnoses the cell voltage measurement line based on the difference between the first and second voltages, and the first voltage.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority under Republic of Korea Patent Application No. 10-2024-0054637 dated April 24, 2024, and all content disclosed in the said Republic of Korea Patent Application is incorporated herein by reference.

[0002] The disclosure concerns battery management systems, battery devices, and diagnostic methods for cell voltage measurement lines. [Background technology]

[0003] Electric vehicles or hybrid vehicles are vehicles that obtain power by driving an electric motor, primarily using a battery as a power source. They are being actively researched as an alternative that can solve the pollution and energy problems associated with internal combustion engine vehicles. Furthermore, batteries are used in a variety of external devices other than vehicles.

[0004] As the maximum output required by external devices increases, more battery cells are used, requiring accurate measurement of the battery cell voltage ("cell voltage") for accurate diagnosis or control of the battery cells. A cell voltage measurement line is used to measure the cell voltage, but if a problem occurs in the cell voltage measurement line, accurate measurement of the cell voltage becomes impossible.

[0005] If the difference between the cell voltage measured without balancing current flowing and the cell voltage measured with balancing current flowing is greater than a predetermined voltage, it can be determined that there is a problem with the cell voltage measurement line. However, when the cell voltage is low, the balancing current is small and the difference between the two voltages is small, so this method can only diagnose the cell voltage measurement line when the cell voltage is high, and it is impossible to diagnose the cell voltage measurement line when the cell voltage is low. [Overview of the project] [Problems that the invention aims to solve]

[0006] In one embodiment, it is possible to provide a battery management system, a battery device, and a method for diagnosing a cell voltage measurement line that can accurately diagnose the cell voltage measurement line.

Means for Solving the Problem

[0007] According to one embodiment, a battery management system for managing battery cells can be provided. The battery management system is connected to the battery cells via a cell voltage measurement line, measures the voltage of the battery cells as a first voltage via the cell voltage measurement line in a state where the cell balancing of the battery cells is disabled, and measures the voltage of the battery cells as a second voltage via the cell voltage measurement line in a state where the cell balancing of the battery cells is enabled. The battery management system can include a battery monitoring circuit and a processor that diagnoses the cell voltage measurement line based on the difference between the first voltage and the second voltage and the first voltage.

[0008] A battery device according to one embodiment includes battery cells, a first cell voltage measurement line connected to the positive electrode of the battery cells, a second cell voltage measurement line connected to the negative electrode of the battery cells, a first resistor connected between the first cell voltage measurement line and a first cell balancing terminal, a switch connected between the first cell balancing terminal and a second cell balancing terminal to which the second cell voltage measurement line is connected, a first voltage between the first cell voltage measurement line and the second cell voltage measurement line measured in a state where the switch is off, a difference between a second voltage between the first cell voltage measurement line and the second cell voltage measurement line measured in a state where the switch is on, and a processor that diagnoses the first cell voltage measurement line or the second cell voltage measurement line based on the difference and the first voltage.

[0009] According to one embodiment, a method can be provided for diagnosing a cell voltage measurement line connected to a battery cell in a battery management system. The method may include the steps of: measuring the voltage of the battery cell as a first voltage via the cell voltage measurement line with cell balancing of the battery cell disabled; measuring the voltage of the battery cell as a second voltage via the cell voltage measurement line with cell balancing of the battery cell enabled; and diagnosing the cell voltage measurement line based on the difference between the first voltage and the second voltage, and the first voltage. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows a battery device according to one embodiment. [Figure 2] This diagram illustrates a diagnostic method for a cell voltage measurement line according to one embodiment. [Figure 3] This diagram illustrates a diagnostic method for a cell voltage measurement line according to one embodiment. [Figure 4] This flowchart shows a diagnostic method for a cell voltage measurement line according to one embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly illustrate the present invention, unnecessary parts have been omitted from the drawings, and similar parts throughout the specification are denoted by similar reference numerals.

[0012] When it is mentioned that one component is "connected" to another, it must be understood that this connection may be direct, or other components may exist in between. Conversely, when it is mentioned that one component is "directly connected" to another, it must be understood that there are no other components in between.

[0013] In the following explanation, expressions written in the singular may be interpreted as singular or plural unless explicitly stated as "one" or "single."

[0014] In the flowchart explained with reference to the diagram, the order of operations can be changed, multiple operations may be merged, certain operations may be split, and certain operations may not be performed.

[0015] Figure 1 shows a battery device according to one embodiment.

[0016] Referring to Figure 1, the battery device 100 can be electrically connected to an external device. In one embodiment, when the external device is a load, the battery device 100 can operate as a power source supplying power to the load and discharge. When the external device is a charger, the battery device 100 can be charged by receiving external power through the charger. In one embodiment, the external device operating as a load may be, for example, an electronic device, a means of transport, or an energy storage system (ESS), and the means of transport may be, for example, a vehicle such as an electric vehicle, a hybrid vehicle, or a smart mobility device.

[0017] The battery device 100 may include a battery module 110 and a battery management system (BMS) 120.

[0018] The battery module 110 may include a plurality of battery cells (not shown). In one embodiment, the plurality of battery cells can be connected in series. In one embodiment, a predetermined number of battery modules 110 can be connected in series or in parallel to supply a desired power. Each of the plurality of battery cells in the battery module 110 can be connected to the battery management system 120 via wiring (cell voltage measurement lines). The battery management system 120 can collect and analyze information about the battery cells to control charging and discharging of the battery cells, cell balancing, protection operations, etc. The battery management system 120 may include a battery monitoring circuit 121 and a processor 122.

[0019] The battery monitoring circuit 121 is connected to each of the multiple battery cells contained in the battery module 110 via cell voltage measurement lines, allowing for monitoring of the state of the battery cells (e.g., cell voltage). In one embodiment, the battery monitoring circuit 121 may include multiple battery monitoring circuits 121, each corresponding to a multiple battery module 110. In one embodiment, one battery monitoring circuit 121 may correspond to two or more battery modules 110, or two or more battery monitoring circuits 121 may correspond to one battery module 110. In one embodiment, the battery monitoring circuit 121 may include a battery monitoring IC (BMIC) provided as an integrated circuit (IC).

[0020] The battery monitoring circuit 121 may include multiple cell balancing circuits (not shown) corresponding to multiple battery cells. Each cell balancing circuit can perform cell balancing for its corresponding battery cell. The battery monitoring circuit 121 can measure (or detect) the cell voltage of each of the multiple battery cells. The processor 122 can transmit a control signal to the battery monitoring circuit 121 to control the cell balancing corresponding to each battery cell, according to the cell voltage of that battery cell.

[0021] The processor 122 can diagnose the cell voltage measurement line by controlling cell balancing. With the processor 122 disabled, the battery monitoring circuit 121 can measure the cell voltage of the battery cell via the cell voltage measurement line. Also, with the processor 122 enabled, the battery monitoring circuit 121 can measure the cell voltage of the battery cell via the cell voltage measurement line. The processor 122 can diagnose the cell voltage measurement line connected to the battery cell based on the cell voltage measured with cell balancing disabled and the cell voltage measured with cell balancing enabled. The processor 122 can diagnose an abnormality in the cell voltage measurement line if the ratio of the difference between the cell voltage with cell balancing disabled and the cell voltage with cell balancing enabled to the cell voltage (for example, the cell voltage with cell balancing disabled) is higher than a threshold ratio.

[0022] In one embodiment, the processor 122 may be a processing circuitry, for example, a microcontroller unit (MCU).

[0023] FIG. 2 and FIG. 3 are diagrams for explaining a method for diagnosing a cell voltage measurement line according to an embodiment. In FIGS. 2 and 3, for convenience of explanation, one battery cell is shown.

[0024] Referring to FIGS. 2 and 3, for voltage measurement of the battery cell CV N cell voltage measurement lines 211 and 212 can be respectively connected to the positive electrode and the negative electrode. The cell voltage measurement line 211 N may be a cell voltage measurement line connected to the negative electrode of the battery cell CV N+1 adjacent to the battery cell CV N or the cell voltage measurement line 212 may be a cell voltage measurement line connected to the positive electrode of the battery cell CV N-1 adjacent to the battery cell CV

[0025] The battery management system can include a resistor 221 connected between the cell voltage measurement line 211 and the cell terminal CT N and a resistor 222 connected between the cell voltage measurement line 212 and the cell terminal CT N-1 For example, one end of the cell voltage measurement line 211 may be connected to the positive electrode of the battery cell CV N the other end (node) N1 of the cell voltage measurement line 211 may be connected to the first terminal of the resistor 221, and the second terminal of the resistor 221 may be connected to the cell terminal CT N Similarly, one end of the cell voltage measurement line 212 may be connected to the negative electrode of the battery cell CV N the other end (node) N2 of the cell voltage measurement line 212 may be connected to the first terminal of the resistor 222, and the second terminal of the resistor 222 may be connected to the cell terminal CT N-1

[0026] The battery management system can include a balancing resistor 231 and a balancing switch 240. The balancing resistor 231 N can be connected between the cell voltage measurement line 211 and the cell balancing terminal CB N ​It can be connected between them. The balancing switch 240 has a cell balancing terminal CB N and cell balancing terminal CB N-1 It can be connected between them. Cell balancing terminal CB N-1 It can be connected to the cell voltage measurement line 212. For example, the cell balancing terminal CB N-1 It can be connected to the second end N2 of the cell voltage measurement line 212. In one embodiment, the cell voltage measurement line 212 and the cell balancing terminal CB N-1 A balancing resistor 232 can be connected between them. In this case, the balancing resistor 232 is connected to the battery cell CV N-1 It may be used for cell balancing.

[0027] In one embodiment, cell terminals CTN, CT N-1 A capacitor 260 can be connected between them.

[0028] In one embodiment, cell terminals CTN, CT N-1 and cell balancing terminal CB N , CB N-1 These may be pins of the BMIC250. In this case, the BMIC250 may include the balancing switch 240, as shown in Figures 2 and 3.

[0029] In one embodiment, the cell terminal CT N CT N-1 This is a pin of the BMIC250, and is the cell balancing terminal CB. N , CB N-1 This may be provided separately from the BMIC250.

[0030] Referring again to Figure 2, the battery management system is turned off when the balancing switch 240 is turned off, and the battery cell CV N Voltage V CVN It is possible to measure the following. With the balancing switch 240 turned off, no current flows to the cell voltage measurement lines 211 and 212, so the measured voltage is the battery cell CV. N This can be approximated to the actual voltage.

[0031] Referring to Figure 3, the battery management system has the balancing switch 240 turned on and the battery cell CV N Voltage V CVN It is possible to measure the battery cell CV by turning on the balancing switch 240. N Current can flow from the battery cell CV through the path of the cell voltage measurement line 211, balancing resistor 231, balancing switch 240, balancing resistor 232, and cell voltage measurement line 212. Therefore, the battery management system can control the battery cell CV N Voltage V CVN When measuring the battery cell CV, a voltage drop may occur due to line resistance 213 or 214 present in the cell voltage measurement line 211 or 212. If there is an abnormality in the cell voltage measurement line 211 or 212, the resistance value of line resistance 213 or 214 will increase, so the battery cell CV N Voltage V CVN It can be measured at a low level.

[0032] Therefore, in one embodiment, the battery management system measures the voltage V when the balancing switch 240 is turned off (i.e., cell balancing disabled). CVN (balancing off) and the measured voltage V with the balancing switch 240 turned ON (i.e., cell balancing enabled). CVN Based on the difference with (balancing on), it is possible to diagnose whether there is an abnormality in the cell voltage measurement line 211 or 212.

[0033] On the other hand, battery cell CV N When the voltage is low, the current flowing through balancing resistors 231 and 232 is small, so the voltage drop across line resistors 213 and 214 is small. In this case, the measured voltage V with balancing switch 240 turned off is CVN (balancing off) and the measured voltage V with the balancing switch 240 turned on. CVNIf the abnormality of cell voltage measurement line 211 or 212 is diagnosed solely by the difference with (balancing on), the difference between the two voltages may be small, and cell voltage measurement line 211 or 212 may not be diagnosed correctly. Therefore, in one embodiment, the battery management system measures the measured voltage V with the balancing switch 240 turned off. CVN (balancing off) and the measured voltage V with the balancing switch 240 turned on. CVN The difference with (balancing on), and battery cell CV N Based on the voltage, an abnormality in the cell voltage measurement line 211 or 212 can be diagnosed. In one embodiment, battery cell CV N The measured voltage V with the balancing switch 240 turned off is the voltage. CVN (balancing off) may be used.

[0034] In one embodiment, the battery management system is defined as shown in Equation 1, battery cell CV N The measured voltage V with the balancing switch 240 turned off, relative to the voltage. CVN (balancing off) and the measured voltage V with the balancing switch 240 turned on. CVN The ratio of the difference with (balancing on) is the threshold ratio V ratio When it is greater than this, it can be diagnosed that there is an abnormality in the cell voltage measurement line 211 or 212. In one embodiment, the threshold ratio V ratio This can be set experimentally and may be set to, for example, 0.02. That is, battery cell CV N The measured voltage V with the balancing switch 240 turned off, relative to the voltage. CVN (balancing off) and the measured voltage V with the balancing switch 240 turned on. CVN If the ratio of the difference with (balancing on) exceeds 0.02, it can be diagnosed that there is an abnormality in the cell voltage measurement line 211 or 212 (for example, an abnormality in the line resistance 213 or 214 of the cell voltage measurement line 211 or 212). [Formula 1]

number

[0035] Thus, battery cell CV N Voltage V CVN (balancing off) The relative difference in measured voltage (|V CVN (balancing off)-V CVN (balancing on)|) is used to diagnose the cell voltage measurement line, so battery cell CV N Even with low voltage, it is possible to accurately diagnose abnormalities in the cell voltage measurement line.

[0036] In one embodiment, the battery management system can diagnose abnormalities in the cell voltage measurement line for each of the multiple battery cells.

[0037] In one embodiment, the battery monitoring circuit of the battery management system (e.g., 121 in Figure 1) is connected to the battery cell CV N The voltage is measured (i.e., detected), and the battery management system processor (e.g., 122 in Figure 1) can diagnose the cell voltage measurement line based on the measured voltage.

[0038] Figure 4 is a flowchart showing a diagnostic method for a cell voltage measurement line according to one embodiment.

[0039] Referring to Figure 4, the battery management system can measure the voltage of the battery cells (first voltage) via the cell voltage measurement line with cell balancing disabled (S410). The battery management system can also measure the voltage of the battery cells (second voltage) via the cell voltage measurement line with cell balancing enabled (S420).

[0040] The battery management system can calculate the ratio of the difference between the battery cell voltage measured with cell balancing disabled (first voltage) and the battery cell voltage measured with cell balancing enabled (second voltage) to the battery cell voltage measured with cell balancing disabled (first voltage) (S430). The battery management system compares the calculated ratio with a threshold ratio (S440), and if the calculated ratio is greater than the threshold ratio, it can diagnose that there is an abnormality in the cell voltage measurement line (S450). In one embodiment, if an abnormality in the cell voltage measurement line is diagnosed, the battery management system can generate an error flag indicating the abnormality in the cell voltage measurement line (S460). In one embodiment, the battery management system can provide the error flag to an external device. This allows the external device (or the user of the external device) to take action regarding the cell voltage measurement line. In one embodiment, if an abnormality in the cell voltage measurement line is diagnosed, the battery management system can shut down the battery management system to prevent the battery device from catching fire. If the calculated ratio is not greater than the threshold ratio, the battery management system can diagnose that there is no abnormality in the cell voltage measurement line (S470).

[0041] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art, utilizing the basic concepts of the present invention as defined in the following claims, also fall within the scope of the present invention.

Claims

1. A battery management system for managing battery cells, A battery monitoring circuit is connected to the battery cell via a cell voltage measurement line, and measures the voltage of the battery cell as a first voltage via the cell voltage measurement line when the cell balancing of the battery cell is disabled, and measures the voltage of the battery cell as a second voltage via the cell voltage measurement line when the cell balancing of the battery cell is enabled. A processor that diagnoses the cell voltage measurement line based on the difference between the first voltage and the second voltage, and the first voltage. A battery management system including...

2. The battery management system according to claim 1, wherein the processor diagnoses that there is an abnormality in the cell voltage measurement line when the ratio of the difference between the first voltage and the second voltage with respect to the first voltage exceeds a threshold ratio.

3. The battery management system according to claim 2, wherein the processor provides an error flag indicating an abnormality in the cell voltage measurement line to an external device to which the battery device including the battery management system is connected.

4. The cell voltage measurement line includes a first cell voltage measurement line connected between the positive electrode of the battery cell and a first node, and a second cell voltage measurement line connected between the negative electrode of the battery cell and a second node. The battery management system further includes a first resistor connected between the first node and the first cell balancing terminal, The battery monitoring circuit includes a switch connected between the first cell balancing terminal and the second cell balancing terminal, which disables the cell balancing when the switch is turned off and enables the cell balancing when the switch is turned on. A battery management system according to any one of claims 1 to 3.

5. The battery management system according to claim 4, further comprising a second resistor connected between the second node and the second cell balancing terminal.

6. Battery cells and A first cell voltage measurement line connected to the positive electrode of the battery cell, A second cell voltage measurement line connected to the negative electrode of the aforementioned battery cell, A first resistor connected between the first cell voltage measurement line and the first cell balancing terminal, A switch is connected between the first cell balancing terminal and the second cell balancing terminal to which the second cell voltage measurement line is connected, A processor that diagnoses the first cell voltage measurement line or the second cell voltage measurement line based on the difference between a first voltage measured between the first cell voltage measurement line and the second cell voltage measurement line with the switch turned off and a second voltage measured between the first cell voltage measurement line and the second cell voltage measurement line with the switch turned on, and the first voltage. A battery device including a battery.

7. The battery device according to claim 6, wherein the processor diagnoses that there is an abnormality in the first cell voltage measurement line or the second cell voltage measurement line if the ratio of the difference between the first voltage and the second voltage with respect to the first voltage exceeds a threshold ratio.

8. The battery device according to claim 7, wherein the processor provides an error flag indicating an abnormality in the first cell voltage measurement line or the second cell voltage measurement line to an external device to which the battery device is connected.

9. The battery device according to claim 7 or 8, further comprising a second resistor connected between the second cell voltage measurement line and the second cell balancing terminal.

10. A method for diagnosing a cell voltage measurement line connected to a battery cell in a battery management system, The steps include: measuring the voltage of the battery cell as a first voltage via the cell voltage measurement line with the cell balancing of the battery cell disabled; The steps include: measuring the voltage of the battery cell as a second voltage via the cell voltage measurement line while cell balancing of the battery cell is enabled; The difference between the first voltage and the second voltage, and the step of diagnosing the cell voltage measurement line based on the first voltage. A method that includes this.

11. The method according to claim 10, wherein the diagnostic step includes diagnosing that there is an abnormality in the cell voltage measurement line if the ratio of the difference between the first voltage and the second voltage with respect to the first voltage exceeds a threshold ratio.

Images