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

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 powered vehicles (EV, HEV, PHEV) and large-capacity energy storage systems (ESS), and interest and demand for technology to accurately diagnose errors in current sensors that detect the charge / discharge current of secondary battery cells is increasing rapidly.

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

[0005] Conventionally, when two or more current sensors are used on the same current line in a system, a method has been widely used to diagnose errors in the current sensors by comparing a difference between two measured current values ​​with a reference value.

[0006] However, when a preset (fixed) reference value is used regardless of the magnitude of the measured current, there is a problem in that the current sensor error diagnosis is not precise. For example, when a reference value is calculated based on a large amount of current, a problem may occur in which a current sensor that is out of the actual reference range is erroneously diagnosed as normal when the measured current is small. Conversely, when a reference value is calculated based on a small amount of current, a problem may occur in which a current sensor that is within the actual reference range is erroneously diagnosed as defective when the measured current is large. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a current sensor diagnosis method for precisely diagnosing a current sensor failure by using a reference value corresponding to the magnitude of a current measured by the current sensor, rather than a fixed reference value, and a current sensor diagnosis 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 diagnosis system, comprising: 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 a 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 a maximum current value of the current section by a preset error ratio.

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

[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 magnitudes, calculate a difference value between the first current value and the second current value, and compare the difference value with a section reference value corresponding to the selected current section to diagnose states 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 a 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 diagnosing 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 to 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 value between the first current value and the second current value with the section reference value, and diagnosing a state of the first current sensor and the second current sensor based on a result of the comparison.

[0018] The step of determining 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 step of determining 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 condition may diagnose at least one of the first current sensor and the second current sensor as being in a faulty state if the difference value is equal to or greater than the section reference value. Effect of the Invention

[0021] The present invention can reduce the possibility of misdiagnosis of a current sensor by using a reference value that corresponds 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, and therefore can diagnose current sensor errors in the same manner regardless of the type of system in which the current sensor is used, 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 or not an error has occurred in the current sensors, thereby making it possible to accurately diagnose 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 decrease in the response speed or phase delay of the current sensor. [Brief description 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 an embodiment. [Diagram 2] FIG. 2 is an exemplary diagram illustrating a method for setting a reference value according to an embodiment. [Diagram 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. [Diagram 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 providing a current sensor diagnostic method according to another embodiment. [Figure 8] FIG. 8 is a flowchart illustrating a method for diagnosing a current sensor according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings, and the same or similar components will be given the same or similar drawing numbers, and duplicated descriptions thereof will be omitted. The suffixes "module" and / or "part" for components used in the following description are given or mixed for the sake of ease of specification writing only, and do not have any meaning or role that is different from each other. In addition, 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, the detailed description will be omitted. In addition, the accompanying drawings are only for making the embodiments disclosed herein easy to understand, and the technical ideas disclosed herein are not limited by the accompanying drawings, and should be understood to include all modifications, equivalents, or alternatives included in the ideas 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 referred to as being "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. In contrast, when a component is referred to as being "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0028] In this application, terms such as "comprise" or "have" are intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof set forth 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 diagnosis system for providing a current sensor diagnosis method according to an embodiment, and FIG. 2 is an example 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 occurs 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 failure of the current sensor based on a first current value and a second current value sensed by two specific current sensors among the plurality of 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 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 timing 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 timing 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 constituted by a Hall sensor or a sense resistor. The diagnostic device 5 receives the voltage signal output from the Hall sensor or the voltage applied between 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 between 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. In addition, each of the first current sensor 1 and the second current sensor 3 is 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 can determine a difference value between the first current value and the second current value, and compare the difference value with a section reference value to diagnose a malfunction of 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, when at least one of the first current sensor 1 and the second current sensor 3 is configured with a Hall sensor, the control unit 53 estimates the current value based on a voltage signal transmitted by the Hall sensor. As another example, when at least one of the first current sensor 1 and the second current sensor 3 is configured with a sense resistor, the control unit 53 estimates 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 50A. Referring to FIG. 2, the first current range A may correspond to an interval of current magnitude between 0A and 50A, the second current range B may correspond to an interval of current magnitude between 50A and 100A, and the third current range C may correspond to an interval of current magnitude between 100A and 150A. In FIG. 2, only the first current range A to the third current range C are shown, but the current range is not limited thereto. In addition to the ranges shown in FIG. 2, a fourth range (D: between 150A and 200A), a fifth range (D: between 200A and 250A), etc. may be further included.

[0045] Next, the control unit 53 determines a section reference value corresponding to the selected current section. According to an embodiment, the section reference value for diagnosing whether the first current sensor 1 and the second current sensor 3 are faulty is not a fixed value, but may be determined according to 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, it is assumed that the preset error ratio is 10%. Since the minimum current value is 0A and the maximum current value is 50A 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 5A (50A×0.1=5A). In a similar manner, the section reference value TH_B of the second current section B may be determined as 10A (100A×0.1=10A), and the section reference value TH_C of the third current section C may be determined as 1A (150A×0.1=15A).

[0047] According to another embodiment, the section reference value may be determined by multiplying the minimum current value of each current section by a preset error ratio. According to 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 previously set error ratio in each of a plurality of current sections. The previously set error ratio reflects a measurement error such as a structural problem in the current sensor itself or in the circuit, and may be determined by an experiment or the like. For example, the previously set error ratio may be determined as a ratio belonging to 10% or more and 15% or less, but is not limited thereto.

[0049] The control unit 53 may calculate the interval reference value every 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 every time a fault in the current sensor is diagnosed.

[0050] Next, the control unit 53 can compare the difference value between the first current value and the second current value with a section reference value to diagnose a fault state of 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 the 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 a 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 the battery system, the charging current may be measured as a positive (+) value, and the discharging current may be measured as a negative (-) value.

[0055] In Fig. 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 previously set 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%). That is, 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, according to the method 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] A plurality of upper limit values ​​corresponding to a plurality of current values ​​in the entire current section are calculated, and the calculated plurality of upper limit values ​​are linked to determine the upper limit line (C_max) of Fig. 3. Also, a plurality of lower limit values ​​corresponding to a plurality of current values ​​are calculated, and the calculated plurality of lower limit values ​​are linked to determine the lower limit line (C_min) of Fig. 3.

[0058] 3, the multiple upper limit values ​​can be determined (-170A, -120A, -70A, -20A, 30A, 80A, 130A, 180A, 230A) 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 multiple upper limit values ​​(I_max: -170A, -120A, -70A, -20A, 30A, 80A, 130A, 180A, 230A).

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

[0060] In FIG. 3, an area D1 between an upper limit line (C_max) and a lower limit line (C_min) may be a normal range. An area outside the normal range D1 may be a fault range. From a theoretical point of view, since the first current sensor 1 and the second current sensor 3 measure the same current, the points indicating the first current value and the second current value can be diagnosed as being in a normal state only if they are located on a line with a slope of 1. However, taking into account the tolerance of the current sensors, if the points corresponding to the first current value and the second current value belong to the normal state area D, the current sensors 1 and 3 can be determined to be in a normal state.

[0061] When the first current sensor 1 and the second current sensor 3 are diagnosed in the manner shown in Fig. 3, many erroneous diagnoses may occur in the low current range. This is because the fixed reference value (30A) is calculated by multiplying the maximum current value (Max Current, 200A) by a preset error ratio (15%), and the fixed reference value (30A) calculated in this manner is applied to all current ranges in the same way. For example, in a range where the current magnitude is small (e.g., over 0A to 50A or less), the difference value between the first current value and the second current value may be significantly lower than the fixed reference value (30A). In this case, the control unit 53 may erroneously diagnose the first current sensor 1 and the second current sensor 3 as being in a normal state, even though they are actually in a fault 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 the fixed reference values ​​Th_1 and Th_2 in both positive and negative current value ranges, the accuracy of fault diagnosis varies significantly. In the case of a current sensor diagnosis method according to an embodiment (and a current sensor diagnosis system and a battery system providing the method), such a problem can be solved, and a more detailed description will be given below with reference to FIGS. 5 and 6.

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

[0064] 5, 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. 5 and 7, in the battery system, the charging current may be measured as a positive (+) value, and the discharging current may be measured as a negative (-) value.

[0065] 5, 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 200 A, the minimum current value (Min Current) is -200 A, the preset error ratio is 15%, and a plurality of current sections can be distinguished at intervals of 50 A. In addition, according to one embodiment, the section reference value can be determined by multiplying the maximum current value of each section by the error ratio. In this case, the section reference value can be different for each current section according to the method 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 in each of a plurality of current sections and concatenating the plurality of upper limit values ​​corresponding to each of the entire current sections (hereinafter, the first to fourth current sections), it is possible to determine the upper limit line (C_max) shown by the solid line in Fig. 5. Furthermore, by calculating a lower limit value corresponding to a predetermined current value in each of a plurality of current sections and concatenating the plurality of lower limit values ​​corresponding to each of the entire current sections (hereinafter, the first to fourth current sections), it is possible to determine the lower limit line (C_min) shown by the dotted line in Fig. 5.

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

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

[0070] 5 (over 100A and under 150A), the section 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 (more than 150A and less than 200A) in FIG. 5, the section reference value is 30A (200A x 0.15 = 30A). For example, the upper limit value corresponding to 200A, which is the maximum current value (I_max) in the fourth current section (more than 150A and less than 200A), is 230A (200A + 30A = 230A), and the lower limit value is 170A (200A - 30A = 170A). In a similar manner to the above, the upper limit value and the lower limit value can be calculated for each of the multiple positive current sections (first to fourth current sections) and multiple negative current sections having 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 outer area outside the normal range D1 may be the failure range. In the case of 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 FIG. 6, the X-axis is the first current value and the second current value, the Y1-axis is the fixed reference value, and the Y2-axis is the accuracy of fault diagnosis shown in percentiles (%). It was experimentally confirmed that the accuracy of fault diagnosis is maintained constant when diagnosing a current sensor using the interval reference values ​​Th_1 and Th_2 in both positive and negative current value ranges. In other words, compared to the case of FIG. 4, it can be seen that the accuracy is significantly improved when diagnosing a fault in a current sensor using the interval reference values ​​compared to when a fixed reference value is used.

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

[0075] The battery system of FIG. 7 is an example of a system for providing a current sensor diagnosis method, and is not limited thereto. The current sensor diagnosis system of FIG. 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 through wiring. The BMS 50 collects and analyzes various information on the battery cells, including information on the plurality of battery cells (Cell1-Celln), to control charging, discharging, protection operations, etc. of the battery cells, and to control the operation of the relay 20.

[0078] In Fig. 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 the connections between the configurations shown in Fig. 1 are merely examples, and the present invention is not limited thereto.

[0079] The relay 20 controls an electrical connection between the battery system and an 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 separated. In this case, the external device may be a charger in a charging cycle in which the battery 10 is charged by supplying power to the battery 10, and may be a load in a discharging cycle in which 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 can measure a battery current, i.e., a charging current and a discharging current, flowing through the battery 10 and transmit the measurement result to the BMS 50.

[0081] According to an 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 in FIG 1, and the description thereof is replaced with the description of FIG 1.

[0082] The BMS 50 can determine a difference value between the first current value and the second current value, and compare the difference value 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, when 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 a current value based on a voltage signal transmitted by the Hall sensor. As another example, when 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 a 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 distinguished by a predetermined current magnitude. For example, the current ranges may be distinguished by 50A magnitude. Referring to FIG. 2, the first current range A may correspond to a current magnitude interval between 0A and 50A, the second current range B may correspond to a current magnitude interval between 50A and 100A, and the third current range C may correspond to a current magnitude interval between 100A and 150A. In FIG. 2, only the first current range A to the third current range C are shown, but the current ranges are not limited thereto. In addition to the ranges shown in FIG. 2, a fourth range (D: between 150A and 200A), a fifth range (D: between 200A and 250A), etc. may be further 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 the presence or absence of a malfunction of the first current sensor 31 and the second current sensor 33 is not a fixed value, but may be determined according to 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, it is assumed that the preset error ratio is 10%. Since the minimum current value is 0A and the maximum current value is 50A 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 5A (50A×0.1=5A). In a similar manner, the section reference value TH_B of the second current section B may be determined as 10A (100A×0.1=10A), and the section reference value TH_C of the third current section C may be determined as 1A (150A×0.1=15A).

[0088] According to another embodiment, the section reference value may be determined by multiplying the minimum current value of each current section by a preset error ratio. According to 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 previously set error ratio in each of a plurality of current sections. The previously set error ratio reflects a measurement error such as a structural problem in the current sensor itself or in the circuit, and may be determined by an experiment or the like. For example, the previously set error ratio may be determined as a ratio belonging to 10% or more and 15% or less, but is not limited thereto.

[0090] The BMS 50 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 already be calculated and stored in the memory 40, and the BMS 50 may extract the interval reference value from the memory 40 each time a fault in the current sensor is diagnosed.

[0091] The BMS 50 can then compare the difference value between the first and second current values ​​with a section 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. Also, 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 result values ​​of the first current sensor 31 and the second current sensor 3.

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

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

[0096] In the following description, the current sensor diagnosis is performed by the BMS 50, but the current sensor diagnosis is 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, when 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, when 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 distinguished by a predetermined current magnitude. For example, the current ranges may be distinguished by 50A magnitude. Referring to FIG. 2, the first current range A may correspond to a current magnitude interval between 0A and 50A, the second current range B may correspond to a current magnitude interval between 50A and 100A, and the third current range C may correspond to a current magnitude interval between 100A and 150A. In FIG. 2, only the first current range A to the third current range C are shown, but the current ranges are not limited thereto. In addition to the ranges shown in FIG. 2, a fourth range (D: between 150A and 200A), a fifth range (D: between 200A and 250A), etc. may be further 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 may be determined according to the current magnitude of a 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, it is assumed that the preset error ratio is 10%. Since the minimum current value is 0A and the maximum current value is 50A in the first current section A, the BMS 50 may determine the section reference value TH_A corresponding to the first current section A to be 5A (50A×0.1=5A). In a similar manner, the section reference value TH_B of the second current section B may be determined to be 10A (100A×0.1=10A), and the section reference value TH_C of the third current section C may be determined to be 1A (150A×0.1=15A).

[0105] As another example, the section reference value may be determined by multiplying the minimum current value of each current section by a preset error ratio.As another 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 may be determined by multiplying a predetermined current value included in each of a plurality of current sections by a preset error ratio. The preset error ratio reflects measurement errors such as structural problems in the current sensor itself or in the circuit, and may be determined by experiments, etc. For example, the preset error ratio may be determined as a ratio between 10% and 15%, but is not limited thereto.

[0107] The BMS 50 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 already be calculated and stored in the memory 40, and the BMS 50 may extract 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 a difference between the first current value and the second current value, and compares the difference with a section reference value (S310).

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

[0111] In step S300, if the comparison result indicates 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 faulty 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 thereto, and various modifications and improvements made by a person having ordinary skill in the field to which the present invention belongs 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 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 states of the first current sensor and the second current sensor; 1. A current sensor diagnostic system comprising:

2. The interval reference value is 2. The current sensor diagnosis system of claim 1, wherein the error ratio is determined by multiplying a predetermined current value among a plurality of current values ​​belonging to the current section by a preset error ratio.

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

4. 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:

5. The control unit is If the difference value is equal to or greater than the section reference value, The current sensor diagnostic system of claim 1 , further comprising: a first current sensor configured to diagnose at least one of the first current sensor and the second current sensor as having a fault condition.

6. 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 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 states of the first current sensor and the second current sensor; Including the battery system.

7. The interval reference value is The battery system of claim 6, wherein 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.

8. The interval reference value is The battery system of claim 7 , wherein the error ratio is determined by multiplying a maximum current value of the current section by a preset error ratio.

9. The BMS includes: If the difference value is equal to or greater than the section reference value, The battery system of claim 6 , further comprising: diagnosing at least one of the first current sensor and the second current sensor as being in a fault condition.

10. 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 value between the first current value and the second current value with the section reference value; and diagnosing conditions of the first current sensor and the second current sensor based on a result of the comparison.

11. The step of determining the interval reference value includes: The current sensor diagnosis method according to claim 10, wherein the section reference value is determined by multiplying a predetermined current value among a plurality of current values ​​belonging to the current section by a preset error ratio.

12. The step of determining the interval reference value includes: The current sensor diagnosis method according to claim 11, wherein the section reference value is determined by multiplying a maximum current value of the current section by a preset error ratio.

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

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