Current sensor diagnostic method, current sensor diagnostic system and battery system providing the method

Abstract

The present invention relates to a current sensor diagnosis method, a current sensor diagnosis system and a battery system that provide the same. The current sensor diagnosis system of the present invention includes a first current sensor, a second current sensor connected in series with the first current sensor, a communication unit that receives a first current value measured by the first current sensor and a second current value measured by the second current sensor, and a control unit that selects a current section to which the first current value and the second current value belong from a plurality of current sections distinguished by current magnitude, calculates a difference value between the first current value and the second current value, and compares the difference value with a section reference value corresponding to the selected current section to diagnose a state of the first current sensor and the second current sensor.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0016120, dated February 8, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a current sensor diagnostic method, a current sensor diagnostic system that provides the method, and a battery system. [Background technology]

[0003] A current sensor is a sensor that detects DC or AC current using a Hall sensor or sense resistor. Recently, the use of secondary battery cells has expanded to include not only mobile devices such as mobile phones and tablet PCs, but also electrically driven vehicles (EV, HEV, PHEV) and large-capacity energy storage systems (ESS), resulting in a surge in interest and demand for technology that can accurately diagnose errors in current sensors that detect the charge / discharge current of secondary battery cells.

[0004] On the other hand, if the current sensor is faulty or not accurate, the measured current value cannot be trusted, and the data calculated based on the current value (e.g., voltage value) cannot be trusted either.

[0005] Conventionally, when two or more current sensors are used on the same current line in a system, a method of diagnosing errors in the current sensors has been widely used, in which the difference between two measured current values ​​is compared with a reference value.

[0006] However, if a preset (fixed) reference value is used regardless of the magnitude of the measured current, there is a problem that the current sensor error diagnosis is inaccurate. For example, if the reference value is calculated based on a large current amount, a current sensor that is outside the actual reference range may be erroneously diagnosed as normal if the measured current is small. Conversely, if the reference value is calculated based on a small current amount, a current sensor that is within the actual reference range may be erroneously diagnosed as defective if the measured current is large. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a current sensor diagnostic method for precisely diagnosing a current sensor failure using a reference value corresponding to the magnitude of the current measured by the current sensor, rather than a fixed reference value, and a current sensor diagnostic system and battery system that provide the method. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a current sensor diagnostic system including: a first current sensor; a second current sensor connected in series with the first current sensor; and a communication unit that receives a first current value measured by the first current sensor and a second current value measured by the second current sensor. and a control unit that selects a current section to which the first current value and the second current value belong from among a plurality of current sections distinguished by current magnitude, calculates a difference value between the first current value and the second current value, and compares the difference value with a section reference value corresponding to the selected current section to diagnose the state of the first current sensor and the second current sensor.

[0009] The section reference value may be determined by multiplying a predetermined current value among a plurality of current values ​​belonging to the current section by a preset error ratio.

[0010] The section reference value may be determined by multiplying the maximum current value of the current section by a preset error ratio.

[0011] The current sensor diagnosis system may further include a storage unit that stores a minimum current value, a maximum current value, and a section reference value for each of the plurality of current sections.

[0012] When the difference value is equal to or greater than the section reference value, the control unit may diagnose at least one of the first current sensor and the second current sensor as being in a faulty state.

[0013] A battery system according to another embodiment of the present invention includes a battery including a plurality of battery cells; a first current sensor connected in series to a current path between the battery and an external device and configured to measure a charging current or a discharging current of the battery; a second current sensor connected in series to the first current sensor and configured to measure the charging current or the discharging current; and a Battery Management System (BMS) configured to receive a first current value measured by the first current sensor and a second current value measured by the second current sensor, select a current section to which the first current value and the second current value belong from a plurality of current sections distinguished by current magnitude, calculate a difference between the first current value and the second current value, and compare the difference with a section reference value corresponding to the selected current section to diagnose a state of the first current sensor and the second current sensor.

[0014] The section reference value may be determined by multiplying a predetermined current value among a plurality of current values ​​belonging to the current section by a preset error ratio.

[0015] The section reference value may be determined by multiplying the maximum current value of the current section by a preset error ratio.

[0016] When the difference value is equal to or greater than the section reference value, the BMS may diagnose at least one of the first current sensor and the second current sensor as being in a fault state.

[0017] A current sensor diagnosis method according to another embodiment of the present invention includes the steps of receiving a first current value measured by a first current sensor and a second current value measured by a second current sensor connected in series with the first current sensor; selecting a current section to which the first current value and the second current value belong from a plurality of current sections distinguished by current magnitude, and determining a section reference value corresponding to the selected current section; comparing a difference between the first current value and the second current value with the section reference value; and diagnosing states of the first current sensor and the second current sensor based on the comparison result.

[0018] The determining of the section reference value may determine the section reference value by multiplying a predetermined current value among a plurality of current values ​​belonging to the current section by a preset error ratio.

[0019] The determining of the section reference value may determine the section reference value by multiplying a maximum current value of the current section by a preset error ratio.

[0020] The step of diagnosing the state may diagnose at least one of the first current sensor and the second current sensor as being in a fault state if the difference value is equal to or greater than the section reference value. [Effects of the Invention]

[0021] The present invention can reduce the possibility of misdiagnosis of the current sensor by using a reference value corresponding to the magnitude of the current measured by the current sensor, rather than a fixed reference value.

[0022] The present invention diagnoses current sensor errors using only the current values ​​of two current sensors, thereby enabling current sensor errors to be diagnosed in the same manner regardless of the type of system using the current sensor, the type of current source, or voltage characteristics, and can be easily applied to various systems including multiple current sensors.

[0023] The present invention compares current values ​​measured by two current sensors simultaneously to determine whether a current sensor error has occurred, thereby accurately diagnosing not only a fault condition in which the current sensor does not work at all, but also a fault case in which a measurement error occurs in the current value due to a slowdown in the response speed or phase delay of the current sensor. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a block diagram illustrating a current sensor diagnostic system that provides a current sensor diagnostic method according to one embodiment. [Figure 2] FIG. 2 is an exemplary diagram illustrating a method for setting a reference value according to an embodiment. [Figure 3] FIG. 3 is a diagram for explaining the fixed reference value. [Figure 4] FIG. 4 is a diagram for explaining the accuracy of fault diagnosis when a fixed reference value is applied. [Figure 5] FIG. 5 is a diagram illustrating the interval reference value according to an embodiment. [Figure 6] FIG. 6 is a diagram for explaining the accuracy of fault diagnosis when the interval reference value is applied. [Figure 7] FIG. 7 is a block diagram illustrating a battery system that provides a current sensor diagnostic method according to another embodiment. [Figure 8] FIG. 8 is a flowchart illustrating a current sensor diagnostic method according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. Identical or similar components will be designated by identical or similar drawing numbers, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "unit" for components used in the following description are given or used interchangeably solely for the convenience of writing the specification, and do not have any distinct meanings or roles. Furthermore, in describing the embodiments disclosed herein, if it is determined that a detailed description of related publicly known technology may obscure the gist of the embodiments disclosed herein, such a detailed description will be omitted. Furthermore, the accompanying drawings are intended only to facilitate understanding of the embodiments disclosed herein, and should not be construed as limiting the technical concepts disclosed herein, and should be understood to include all modifications, equivalents, or alternatives within the concept and technical scope of the present invention.

[0026] Terms including ordinal numbers such as "first," "second," etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0027] When a component is said to be "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is said to be "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0028] In this application, the use of terms such as "comprise" or "have" is intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof stated in the specification, but should be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0029] FIG. 1 is a block diagram illustrating a current sensor diagnostic system that provides a current sensor diagnostic method according to an embodiment, and FIG. 2 is an exemplary diagram illustrating a method for setting a reference value according to an embodiment.

[0030] Referring to FIG. 1, the current sensor diagnostic system includes a first current sensor 1, a second current sensor 3, and a diagnostic device 5.

[0031] The current sensor diagnostic system can diagnose an error that has occurred in at least one of a plurality of current sensors 1 and 3 configured to measure the same current. Although two current sensors 1 and 3 are shown in FIG. 1 and the following FIG. 7, the present invention is not limited to this. In other words, the current sensor diagnostic system includes two or more current sensors that sense the same current, and can diagnose a current sensor failure based on a first current value and a second current value sensed by two specific current sensors among the two current sensors.

[0032] The first current sensor 1 and the second current sensor 3 are configured to measure the same current.

[0033] For example, a series circuit in which the first current sensor 1 and the second current sensor 3 are connected in series may be configured to be connected in series on a current path through which a current flows. As another example, if the first current sensor 1 and the second current sensor 3 are designed to have the same equivalent resistance, a parallel circuit in which the first current sensor 1 and the second current sensor 3 are connected in parallel with each other may be configured to be connected in series on a line through which a current flows.

[0034] According to an embodiment, in a battery system as shown in FIG. 7 below, a first current sensor 1 and a second current sensor 3 may be connected in series to a current line through which a charging current or a discharging current of a battery 10 flows.

[0035] The first current sensor 1 and the second current sensor 3 can measure the same current at the same time and transmit the measured current value to the diagnostic device 5. For example, the first current sensor 1 and the second current sensor 3 can measure the same current at the same time in real time or at predetermined intervals and transmit the measurement result to the diagnostic device 5.

[0036] The first current sensor 1 and the second current sensor 3 may be configured as Hall sensors or sense resistors. The diagnostic device 5 receives the voltage signal output from the Hall sensor or the voltage applied across both terminals of the sense resistor and can determine the magnitude of the current using the voltage signal or the measured voltage. The diagnostic device 5 may include an analog-to-digital converter (ADC) to convert the voltage signal output from the Hall sensor or the voltage applied across both terminals of the sense resistor into a digital value.

[0037] The first current sensor 1 and the second current sensor 3 do not have to be configured with the same type of sensor. For example, the first current sensor 1 may be configured with a Hall sensor, and the second current sensor 3 may be configured with a sense resistor. As another example, the first current sensor 1 may be configured with a sense resistor, and the second current sensor 3 may be configured with a Hall sensor. Furthermore, the first current sensor 1 and the second current sensor 3 are not limited to the above examples, and may be configured with various current sensors.

[0038] The diagnostic device 5 may include a communication unit 51 , a control unit 53 , and a storage unit 55 .

[0039] The communication unit 51 receives the current measurement results transmitted by the first current sensor 1 and the second current sensor 3 , and transmits the received current measurement results to the control unit 53 .

[0040] The control unit 53 determines the difference between the first current value and the second current value, and compares the difference with a section reference value to diagnose a fault in at least one of the first current sensor 1 and the second current sensor 3.

[0041] First, the control unit 53 can determine a first current value measured by the first current sensor 1 and a second current value measured by the second current sensor 3. For example, if at least one of the first current sensor 1 and the second current sensor 3 is a Hall sensor, the control unit 53 can estimate the current value based on a voltage signal transmitted by the Hall sensor. As another example, if at least one of the first current sensor 1 and the second current sensor 3 is a sense resistor, the control unit 53 can estimate the current value based on a voltage value applied between both terminals of the sense resistor. The control unit 53 can determine the first current value of the first current sensor 1 and the second current value of the second current sensor 3 using a conventionally known method.

[0042] Next, the control unit 53 selects a current section to which the first current value and the second current value belong from among a plurality of current sections distinguished by the magnitude of the current.

[0043] The multiple current sections may be distinguished by a predetermined current magnitude.

[0044] For example, the current ranges may be distinguished by 50 A increments. Referring to FIG. 2, the first current range A may correspond to a current range from 0 A to 50 A, the second current range B may correspond to a current range from 50 A to 100 A, and the third current range C may correspond to a current range from 100 A to 150 A. While FIG. 2 shows only the first current range A to the third current range C, the current ranges are not limited to this. In addition to the ranges shown in FIG. 2, a fourth range (D: from 150 A to 200 A), a fifth range (D: from 200 A to 250 A), etc. may also be included.

[0045] Next, the control unit 53 determines a section reference value corresponding to the selected current section. According to one embodiment, the section reference value for diagnosing whether or not the first current sensor 1 and the second current sensor 3 are faulty is not a fixed value, but may be determined based on the current magnitude of the selected current section.

[0046] According to one embodiment, the section reference value may be determined by multiplying the maximum current value of each current section by a preset error ratio. Referring to FIG. 2, for example, assume that the preset error ratio is 10%. Since the minimum current value is 0 A and the maximum current value is 50 A in the first current section A, the control unit 53 may determine the section reference value TH_A corresponding to the first current section A as 5 A (50 A × 0.1 = 5 A). Similarly, the section reference value TH_B for the second current section B may be determined as 10 A (100 A × 0.1 = 10 A), and the section reference value TH_C for the third current section C may be determined as 1 A (150 A × 0.1 = 15 A).

[0047] In another embodiment, the section reference value may be determined by multiplying the minimum current value of each current section by a preset error ratio.In another embodiment, the section reference value may be determined by multiplying the median current value of each current section by a preset error ratio.

[0048] In summary, the section reference value may be determined by multiplying a predetermined current value included in a predetermined current section by a preset error ratio for each of a plurality of current sections. The preset error ratio reflects measurement errors such as structural problems in the current sensor itself or the circuit, and may be determined through experiments, etc. For example, the preset error ratio may be determined as a ratio between 10% and 15%, but is not limited thereto.

[0049] The control unit 53 may calculate the interval reference value each time a fault in the current sensor is diagnosed, or a plurality of interval reference values ​​corresponding to a plurality of current intervals may be calculated and stored in the storage unit 55, and the control unit 53 may extract the interval reference value from the storage unit 55 each time a fault in the current sensor is diagnosed.

[0050] Next, the control unit 53 can compare the difference between the first current value and the second current value with the interval reference value to diagnose a fault state in at least one of the first current sensor 1 and the second current sensor 3.

[0051] For example, if the difference value is equal to or greater than a reference value, the control unit 53 can diagnose at least one of the first current sensor 1 and the second current sensor 3 as being in a faulty state. Also, if the difference value is less than the reference value, the control unit 53 can diagnose both the first current sensor 1 and the second current sensor 3 as being in a normal state.

[0052] The storage unit 55 may store a minimum current value, a maximum current value, and a corresponding section reference value for each of a plurality of current sections. The storage unit 55 may also store current measurement result values ​​of the first current sensor 1 and the second current sensor 3 received through the communication unit 51.

[0053] FIG. 3 is a diagram for explaining the fixed reference value, and FIG. 4 is a diagram for explaining the accuracy of fault diagnosis when the fixed reference value is applied.

[0054] 3, the X-axis may be a first current value measured by the first current sensor 1, and the Y-axis may be a second current value measured by the second current sensor 3. Referring to FIGS. 3 and 7, in a battery system, a charging current may be measured as a positive (+) value, and a discharging current may be measured as a negative (-) value.

[0055] 3, it is assumed that the maximum current value (Max Current) that the first current sensor 1 and the second current sensor 3 can measure is 200A, the minimum current value (Min Current) is -200A, and the preset error ratio is 15%. For example, the fixed reference value can be determined by multiplying the maximum current value (Max Current, 200A) by the error ratio (15%). In other words, the fixed reference value is 30A (200A x 0.15 = 30A). In this case, the fixed reference value is constant regardless of the magnitude of the current measured by the first current sensor 1 and the second current sensor 3, as described below.

[0056] At a given current value, the normal range can be determined as the current value between a lower limit calculated by subtracting a fixed reference value and an upper limit calculated by adding the fixed reference value at the given current value.

[0057] By calculating a plurality of upper limit values ​​corresponding to a plurality of current values ​​in the entire current range and concatenating the calculated plurality of upper limit values, the upper limit line (C_max) of Fig. 3 can be determined. Also, by calculating a plurality of lower limit values ​​corresponding to a plurality of current values ​​and concatenating the calculated plurality of lower limit values, the lower limit line (C_min) of Fig. 3 can be determined.

[0058] 3, the upper limit values ​​(-170A, -120A, -70A, -20A, 30A, 80A, 130A, 180A, 230A) can be determined by adding a fixed reference value (30A) to each current value (e.g., -200A, -150A, -100A, -50A, 0A, 50A, 100A, 150A, 200A). In this case, the upper limit line (C_max) can be determined by concatenating the upper limit values ​​(I_max: -170A, -120A, -70A, -20A, 30A, 80A, 130A, 180A, 230A).

[0059] 3, multiple lower limit values ​​(-230A, -180A, -130A, -80A, -30A, 20A, 70A, 120A, 170A) can be determined by similarly subtracting a fixed reference value (30A) from each current value (e.g., -200A, -150A, -100A, -50A, 0A, 50A, 100A, 150A, 200A, etc.). In this case, the lower limit line (C_min) can be determined by concatenating multiple lower limit values ​​(I_min: -230A, -180A, -130A, -80A, -30A, 20A, 70A, 120A, 170A).

[0060] In Figure 3, the area D1 between the upper limit line (C_max) and the lower limit line (C_min) may be the normal range. The area outside the normal range D1 may be the fault range. From a theoretical perspective, since the first current sensor 1 and the second current sensor 3 measure the same current, the points representing the first and second current values ​​must lie on a line with a slope of 1 to be diagnosed as being in a normal state. However, taking into account the tolerance of the current sensors, if the points corresponding to the first and second current values ​​fall within the normal state area D, the current sensors 1 and 3 can be determined to be in a normal state.

[0061] When diagnosing the first current sensor 1 and the second current sensor 3 using the method shown in Figure 3, misdiagnosis can occur frequently in low current ranges. This is because the fixed reference value (30A) is calculated by multiplying the maximum current value (200A) by a preset error rate (15%), and the fixed reference value (30A) calculated in this manner is applied to all current ranges. For example, in a low current range (e.g., above 0A and below 50A), the difference between the first and second current values ​​may be significantly lower than the fixed reference value (30A). This may cause the control unit 53 to erroneously diagnose the first current sensor 1 and the second current sensor 3 as normal, even though they are actually in a faulty state.

[0062] Referring to FIG. 4, the X-axis represents the first and second current values, the Y1-axis represents the fixed reference value, and the Y2-axis represents the accuracy of fault diagnosis expressed in percentiles (%). It has been experimentally confirmed that when diagnosing a current sensor using fixed reference values ​​Th_1 and Th_2 in both positive and negative current value ranges, the accuracy of fault diagnosis fluctuates significantly. A current sensor diagnosis method (and a current sensor diagnosis system and battery system that implement the method) according to one embodiment can solve this problem, and a more detailed description thereof will be provided below with reference to FIGS. 5 and 6.

[0063] FIG. 5 is a diagram for explaining interval reference values ​​according to an embodiment, and FIG. 6 is a diagram for explaining the accuracy of fault diagnosis when the interval reference values ​​are applied.

[0064] 5, the X-axis may represent a first current value measured by the first current sensor 1, and the Y-axis may represent a second current value measured by the second current sensor 3. Referring to FIGS. 5 and 7, in a battery system, charging current may be measured as a positive (+) value, and discharging current may be measured as a negative (-) value.

[0065] 5, it is assumed that the maximum current value (Max Current) that can be measured by the first current sensor 1 and the second current sensor 3 is 200 A, the minimum current value (Min Current) is -200 A, the preset error rate is 15%, and multiple current ranges can be distinguished at intervals of 50 A. In addition, according to one embodiment, the range reference value can be determined by multiplying the maximum current value of each range by the error rate. In this case, the range reference value can be different for each current range, as described below.

[0066] The normal range corresponding to a given current value can be determined as a current value between a lower limit value calculated by subtracting a section reference value from the current value and an upper limit value calculated by adding the section reference value to the current value.

[0067] By calculating an upper limit value corresponding to a predetermined current value for each of a plurality of current sections and concatenating the plurality of upper limit values ​​corresponding to each of the entire current sections (hereinafter referred to as the first to fourth current sections), the upper limit line (C_max) shown by the solid line in Fig. 5 can be determined. Furthermore, by calculating a lower limit value corresponding to a predetermined current value for each of a plurality of current sections and concatenating the plurality of lower limit values ​​corresponding to each of the entire current sections (hereinafter referred to as the first to fourth current sections), the lower limit line (C_min) shown by the dotted line in Fig. 5 can be determined.

[0068] 5, the reference value is 7.5 A (50 A × 0.15 = 7.5 A). For example, the upper limit value corresponding to 50 A, which is the maximum current value (I_max) in the first current section (0 A to 50 A), is 57.5 A (50 A + 7.5 A = 47.5 A), and the lower limit value is 42.5 A (50 A − 7.5 A = 42.5 A).

[0069] 5 (over 50 A and under 100 A), the section reference value is 15 A (100 A x 0.15 = 15 A). For example, the upper limit value corresponding to 100 A, which is the maximum current value (I_max) in the second current section (over 50 A and under 100 A), is 115 A (100 A + 15 A = 115 A), and the lower limit value is 85 A (100 A - 15 A = 85 A).

[0070] 5 (over 100A and under 150A), the reference value is 22.5A (150A x 0.15 = 22.5A). For example, the upper limit value corresponding to 150A, which is the maximum current value (I_max) in the third current section (over 100A and under 150A), is 172.5A (150A + 22.5A = 172.5A), and the lower limit value is 127.5A (150A - 22.5A = 85A).

[0071] In addition, in the fourth current section (over 150 A and under 200 A) in FIG. 5, the section reference value is 30 A (200 A × 0.15 = 30 A). For example, the upper limit value corresponding to 200 A, which is the maximum current value (I_max) in the fourth current section (over 150 A and under 200 A), is 230 A (200 A + 30 A = 230 A), and the lower limit value is 170 A (200 A - 30 A = 170 A). Using the same method as above, the upper and lower limit values ​​can be calculated for each of the multiple positive current sections (first to fourth current sections) and multiple negative current sections with the same absolute value.

[0072] Referring to FIG. 5, the upper limit line (C_max) can be determined by concatenating the multiple upper limit values ​​(-170A, -127.5A, -85A, -42.5A, 0, 57.5A, 115A, 172.5A, 230A) described above. The lower limit line (C_min) can be determined by concatenating the multiple lower limit values ​​(-230A, -172.5A, -115A, -57.5A, 0, 42.5A, 85A, 127.5A, 170A) described above. In this case, the area D2 between the upper limit line (C_max) and the lower limit line (C_min) may be the normal range. The area outside the normal range D1 may be the fault range. In FIG. 5, it can be seen that the smaller the magnitude (absolute value) of the measured current is, the smaller the section reference value is, and the larger the magnitude (absolute value) of the measured current is, the larger the section reference value is.

[0073] Referring to Figure 6, the X axis represents the first and second current values, the Y axis represents the fixed reference value, and the Y axis represents the percentile (%) of the fault diagnosis accuracy. Experiments have confirmed that the accuracy of fault diagnosis remains consistent when diagnosing current sensors using the interval reference values ​​Th_1 and Th_2 in both positive and negative current ranges. In other words, compared to Figure 4, the accuracy of diagnosing current sensor faults using the interval reference values ​​is significantly improved compared to when using the fixed reference value.

[0074] FIG. 7 is a block diagram illustrating a battery system that provides a current sensor diagnostic method according to another embodiment.

[0075] The battery system of Figure 7 is an example of a system that provides a current sensor diagnostic method, and is not limited thereto. The current sensor diagnostic system of Figure 1 may be included in various systems that require fault diagnosis of a current sensor.

[0076] In FIG. 7, the battery system includes a battery 10, a relay 20, a current sensor 30, a memory 40, and a battery management system (hereinafter referred to as "BMS") 50.

[0077] The battery 10 may include a plurality of battery cells (Cell1-Celln) electrically connected in series and parallel. Each of the plurality of battery cells (Cell1-Celln) is electrically connected to the BMS 50 via wiring. The BMS 50 collects and analyzes various information related to the battery cells, including information about the plurality of battery cells (Cell1-Celln), to control charging, discharging, and protection operations of the battery cells, and to control the operation of the relay 20.

[0078] 1, a battery 10 is connected between two output terminals OUT1 and OUT2 of a battery system, a relay 20 is connected between the positive terminal of the battery system and the first output terminal OUT1, and a current sensor 30 is connected between the negative terminal of the battery system and the second output terminal OUT2. The configurations and connections between the configurations shown in FIG. 1 are merely examples, and the present invention is not limited thereto.

[0079] The relay 20 controls the electrical connection between the battery system and the external device. When the relay 20 is turned on, the battery system and the external device are electrically connected to perform charging or discharging, and when the relay 20 is turned off, the battery system and the external device are electrically disconnected. In this case, the external device may be a charger in a charging cycle that supplies power to the battery 10 to charge it, or a load in a discharging cycle that the battery 10 discharges power to the external device.

[0080] The current sensor 30 is connected in series to a current path between the battery 10 and an external device. The current sensor 30 measures the battery current, i.e., the charging current and discharging current, flowing through the battery 10 and transmits the measurement result to the BMS 50.

[0081] According to one embodiment, the current sensor 30 may include a plurality of current sensors connected in series. For example, the current sensor 30 may include at least two current sensors connected in series, i.e., a first current sensor 31 and a second current sensor 33. The first current sensor 31 and the second current sensor 33 are similar to the first current sensor 1 and the second current sensor 3 described above with reference to FIG. 1, and the description thereof is substituted for the description of FIG. 1.

[0082] The BMS 50 can determine a difference between the first current value and the second current value, and compare the difference with a section reference value to diagnose a fault in at least one of the first current sensor 31 and the second current sensor 33.

[0083] First, the BMS 50 can determine a first current value measured by the first current sensor 31 and a second current value measured by the second current sensor 33. For example, if at least one of the first current sensor 31 and the second current sensor 33 is a Hall sensor, the BMS 50 estimates the current value based on a voltage signal transmitted by the Hall sensor. As another example, if at least one of the first current sensor 31 and the second current sensor 33 is a sense resistor, the BMS 50 estimates the current value based on a voltage value applied between both terminals of the sense resistor. The BMS 50 can determine the first current value of the first current sensor 31 and the second current value of the second current sensor 33 using a conventionally known method.

[0084] Next, the BMS 50 selects a current section to which the first current value and the second current value belong from among a plurality of current sections distinguished by the magnitude of the current.

[0085] The current ranges may be differentiated by a predetermined current magnitude. For example, the current ranges may be differentiated in increments of 50 A. Referring to FIG. 2, the first current range A may correspond to a current range greater than 0 A and less than 50 A, the second current range B may correspond to a current range greater than 50 A and less than 100 A, and the third current range C may correspond to a current range greater than 100 A and less than 150 A. While FIG. 2 only shows the first current range A through the third current range C, the current ranges are not limited thereto. In addition to the ranges shown in FIG. 2, a fourth range (D: greater than 150 A and less than 200 A), a fifth range (D: greater than 200 A and less than 250 A), etc. may also be included.

[0086] Next, the BMS 50 determines a section reference value corresponding to the selected current section. According to one embodiment, the section reference value for diagnosing whether or not there is a failure in the first current sensor 31 and the second current sensor 33 is not a fixed value, but may be determined based on the current magnitude of the selected current section.

[0087] According to one embodiment, the section reference value may be determined by multiplying the maximum current value of each current section by a preset error ratio. Referring to FIG. 2, for example, assume that the preset error ratio is 10%. Since the minimum current value is 0 A and the maximum current value is 50 A in the first current section A, the BMS 50 may determine the section reference value TH_A corresponding to the first current section A as 5 A (50 A × 0.1 = 5 A). Similarly, the section reference value TH_B for the second current section B may be determined as 10 A (100 A × 0.1 = 10 A), and the section reference value TH_C for the third current section C may be determined as 1 A (150 A × 0.1 = 15 A).

[0088] In another embodiment, the section reference value may be determined by multiplying the minimum current value of each current section by a preset error ratio.In another embodiment, the section reference value may be determined by multiplying the median current value of each current section by a preset error ratio.

[0089] In summary, the section reference value may be determined by multiplying a predetermined current value included in a predetermined current section by a preset error ratio for each of a plurality of current sections. The preset error ratio reflects measurement errors such as structural problems in the current sensor itself or the circuit, and may be determined through experiments, etc. For example, the preset error ratio may be determined as a ratio between 10% and 15%, but is not limited thereto.

[0090] The BMS 50 can calculate the interval reference value each time a fault in the current sensor is diagnosed, or multiple interval reference values ​​corresponding to multiple current intervals can be calculated and stored in the memory 40, and the BMS 50 can retrieve the interval reference value from the memory 40 each time a fault in the current sensor is diagnosed.

[0091] Next, the BMS 50 can compare the difference between the first and second current values ​​with the interval reference value to diagnose a fault condition in at least one of the first current sensor 31 and the second current sensor 33.

[0092] For example, if the difference value is equal to or greater than a reference value, the BMS 50 can diagnose at least one of the first current sensor 31 and the second current sensor 33 as being in a faulty state. Alternatively, if the difference value is less than the reference value, the BMS 50 can diagnose both the first current sensor 31 and the second current sensor 33 as being in a normal state.

[0093] The memory 40 may store a minimum current value, a maximum current value, and a corresponding section reference value for each of a plurality of current sections. The memory 40 may also store current measurement results of the first current sensor 31 and the second current sensor 33.

[0094] FIG. 8 is a flowchart illustrating a current sensor diagnostic method according to another embodiment.

[0095] Hereinafter, a current sensor diagnostic method, a current sensor diagnostic system that provides the method, and a battery system will be described with reference to FIGS.

[0096] In the following description, the BMS 50 will be described as the entity that performs the current sensor diagnosis, but the current sensor diagnosis is the same as being performed by the control unit 53 of the current sensor diagnosis system 5. Differences between the current sensor diagnosis system and the battery system will be described separately below.

[0097] First, the BMS 50 receives the first current value measured by the first current sensor 31 and the second current value measured by the second current sensor 33 (S100).

[0098] For example, if at least one of the first current sensor 31 and the second current sensor 33 is configured with a Hall sensor, the BMS 50 estimates the current value based on a voltage signal transmitted by the Hall sensor. As another example, if at least one of the first current sensor 31 and the second current sensor 33 is configured with a sense resistor, the BMS 50 estimates the current value based on a voltage value applied between both terminals of the sense resistor. The BMS 50 can determine the first current value of the first current sensor 31 and the second current value of the second current sensor 33 using a conventionally known method.

[0099] Next, the BMS 50 determines section reference values ​​corresponding to the first current value and the second current value (S100).

[0100] In step S100, the BMS 50 may select a current section to which the first current value and the second current value belong from among a plurality of current sections distinguished by the magnitude of the current.

[0101] The current ranges may be differentiated by a predetermined current magnitude. For example, the current ranges may be differentiated in increments of 50 A. Referring to FIG. 2, the first current range A may correspond to a current range greater than 0 A and less than 50 A, the second current range B may correspond to a current range greater than 50 A and less than 100 A, and the third current range C may correspond to a current range greater than 100 A and less than 150 A. While FIG. 2 only shows the first current range A through the third current range C, the current ranges are not limited thereto. In addition to the ranges shown in FIG. 2, a fourth range (D: greater than 150 A and less than 200 A), a fifth range (D: greater than 200 A and less than 250 A), etc. may also be included.

[0102] In step S100, the BMS 50 can determine a section reference value corresponding to the selected current section.

[0103] According to one embodiment, the section reference value for diagnosing whether the first current sensor 31 and the second current sensor 33 are faulty is not a fixed value, but can be determined based on the current magnitude of the selected current section.

[0104] For example, the section reference value may be determined by multiplying the maximum current value of each current section by a preset error ratio. Referring to FIG. 2, for example, assume that the preset error ratio is 10%. Since the minimum current value is 0 A and the maximum current value is 50 A in the first current section A, the BMS 50 may determine the section reference value TH_A corresponding to the first current section A as 5 A (50 A × 0.1 = 5 A). In a similar manner, the section reference value TH_B for the second current section B may be determined as 10 A (100 A × 0.1 = 10 A), and the section reference value TH_C for the third current section C may be determined as 1 A (150 A × 0.1 = 15 A).

[0105] For example, the section reference value may be determined by multiplying the minimum current value of each current section by a preset error ratio. For example, the section reference value may be determined by multiplying the median current value of each current section by a preset error ratio.

[0106] In summary, the section reference value can be determined for each of a plurality of current sections by multiplying a predetermined current value included in the current section by a preset error ratio. The preset error ratio reflects measurement errors such as structural problems in the current sensor itself or the circuit, and can be determined through experiments, etc. For example, the preset error ratio can be determined as a ratio between 10% and 15%, but is not limited thereto.

[0107] The BMS 50 can calculate the interval reference value each time a fault in the current sensor is diagnosed, or multiple interval reference values ​​corresponding to multiple current intervals can be calculated and stored in the memory 40, and the BMS 50 can retrieve the interval reference value from the memory 40 each time a fault in the current sensor is diagnosed.

[0108] Next, the BMS 50 compares the difference between the first and second current values ​​with a section reference value, and diagnoses a fault state of at least one of the first current sensor 31 and the second current sensor 33 based on the comparison result (S300).

[0109] In step S300, the BMS 50 calculates the difference between the first current value and the second current value, and compares the difference with the interval reference value (S310).

[0110] In step S300, if the comparison result shows that the difference value is less than the interval reference value (S310, Yes), the BMS 50 diagnoses both the first current sensor 31 and the second current sensor 33 as normal (S330).

[0111] In step S300, if the comparison result shows that the difference value is equal to or greater than the section reference value (S310, No), the BMS 50 diagnoses at least one of the first current sensor 31 and the second current sensor 33 as being in a fault state (S350).

[0112] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these examples, and various modifications and improvements made by those skilled in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. A first current sensor; a second current sensor connected in series with the first current sensor; a communication unit that receives a first current value measured by the first current sensor and a second current value measured by the second current sensor; a control unit that selects a current section to which the first current value and the second current value belong from a plurality of current sections distinguished by current magnitude, calculates a difference value between the first current value and the second current value, and compares the difference value with a section reference value corresponding to the selected current section to diagnose the states of the first current sensor and the second current sensor; Including, The interval reference value is The current sensor diagnostic system determines the error ratio by multiplying a predetermined current value among a plurality of current values ​​belonging to the current range by a preset error ratio.

2. The interval reference value is The current sensor diagnostic system according to claim 1 , wherein the error rate is determined by multiplying a maximum current value of the current section by a preset error rate.

3. a storage unit for storing a minimum current value, a maximum current value, and a section reference value for each of the plurality of current sections; The current sensor diagnostic system of claim 1 further comprising:

4. The control unit If the difference value is equal to or greater than the interval reference value, The current sensor diagnostic system of claim 1 , wherein at least one of the first current sensor and the second current sensor is diagnosed as being in a fault condition.

5. A battery including a plurality of battery cells; a first current sensor connected in series to a current path between the battery and an external device, the first current sensor measuring a charging current or a discharging current of the battery; a second current sensor connected in series with the first current sensor to measure the charging current or the discharging current; a BMS that receives a first current value measured by the first current sensor and a second current value measured by the second current sensor, selects a current section to which the first current value and the second current value belong from a plurality of current sections distinguished by current magnitude, calculates a difference between the first current value and the second current value, and compares the difference with a section reference value corresponding to the selected current section to diagnose states of the first current sensor and the second current sensor; Including, The interval reference value is The battery system is configured such that the error ratio is determined by multiplying a predetermined current value among a plurality of current values ​​belonging to the current range by a preset error ratio.

6. The interval reference value is The battery system of claim 5 , wherein the error ratio is determined by multiplying a maximum current value of the current section by a preset error ratio.

7. The BMS includes: If the difference value is equal to or greater than the interval reference value, The battery system of claim 5 , wherein at least one of the first current sensor and the second current sensor is diagnosed as being in a fault condition.

8. A step of receiving a first current value measured by a first current sensor and a second current value measured by a second current sensor connected in series with the first current sensor; selecting a current section to which the first current value and the second current value belong from among a plurality of current sections distinguished by current magnitude, and determining a section reference value corresponding to the selected current section; comparing a difference between the first current value and the second current value with the section reference value; diagnosing the states of the first current sensor and the second current sensor based on the results of the comparison; The step of determining the interval reference value includes: The current sensor diagnosis method determines the section reference value by multiplying a predetermined current value among a plurality of current values ​​belonging to the current section by a preset error ratio.

9. The step of determining the interval reference value includes: The current sensor diagnosis method according to claim 8, wherein the section reference value is determined by multiplying a maximum current value of the current section by a preset error ratio.

10. The step of diagnosing the condition comprises: If the difference value is equal to or greater than the interval reference value, The method of diagnosing a current sensor according to claim 8 , further comprising diagnosing at least one of the first current sensor and the second current sensor in a fault condition.

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