Method for detecting incorrect assembly of current sensors

Abstract

The system appropriately detects incorrect assembly of the first and second current sensors, which are used to detect the current flowing through the secondary battery. [Solution] The method for detecting misassembly of current sensors is a method in which a computer detects misassembly of first and second current sensors, which are used to detect the current flowing through a secondary battery mounted on a vehicle. The method includes calculating the slope Ka of the current detected using the first current sensor and the slope Kb of the current detected using the second current sensor during discharge or charging of the secondary battery, and determining that there is a possibility of misassembly of either the first or second current sensor if the calculated slopes Ka and Kb satisfy the relationship of the following formula. [Math 1] TIFF2026055676000005.tif6150

Description

Technical Field

[0001] This disclosure relates to detection of misassembly of first and second current sensors for respectively detecting currents flowing through a secondary battery.

Background Art

[0002] Patent Document 1 discloses an abnormality determination device applied to a power supply system having a first current sensor and a second current sensor that respectively detect currents flowing through a storage battery. The abnormality determination device determines the presence or absence of an abnormality in the first and second current sensors based on a comparison result between first and second change amounts of the remaining capacity of the storage battery calculated from the detected currents of the first and second current sensors and a third change amount calculated from the voltage of the storage battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, since abnormality determination of the current sensor is performed based on the comparison result of the change amount of the remaining capacity of the storage battery, it is difficult to appropriately detect misassembly of the current sensor, which is an initial abnormality with almost no change in the remaining capacity.

Means for Solving the Problems

[0005] The method for detecting misassembly of current sensors according to this disclosure is a method by which a computer detects misassembly of first and second current sensors, which are used to detect the current flowing through a secondary battery mounted in a vehicle. The method includes calculating the slope Ka of the current detected using the first current sensor and the slope Kb of the current detected using the second current sensor during the discharge or charging of the secondary battery, and determining that there is a possibility of misassembly of either the first or second current sensor if the calculated slopes Ka and Kb satisfy the relationship of the following formula.

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[0006] According to this disclosure, by utilizing the fact that the relationship between the slopes Ka and Kb in equation (1) is satisfied during charging or discharging of the secondary battery, it becomes possible to detect the possibility of misassembly of either the first or second current sensor. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram schematically shows an example of the functional configuration of a vehicle according to the embodiment. [Figure 2] (A) is a graph showing the relationship between the measured voltage V and the detected current I for the first and second current sensors, and (B) is a figure showing the characteristics used to detect incorrect assembly of the first and second current sensors. [Figure 3] This flowchart shows an example of the processing flow for detecting incorrect assembly of the first and second current sensors according to the embodiment. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described with reference to the attached drawings.

[0009] 1. Vehicle configuration Figure 1 is a schematic diagram showing an example of the functional configuration of a vehicle 10 according to this embodiment. The vehicle 10 is an electric vehicle such as a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), and a fuel cell electric vehicle (FCEV). The vehicle 10 is equipped with a battery 12, a high-voltage unit 14, first and second current sensors 16a and 16b, and an electronic control unit (ECU) 18.

[0010] Battery 12 is a secondary battery such as a lithium-ion battery. Battery 12 is connected to a high-voltage unit 14 via a high-potential power line 20 and a low-potential power line 22. Examples of high-voltage units 14 include electric motors for vehicle operation, DC / DC converters, air conditioning inverters, water heaters, AC chargers, solar chargers, etc.

[0011] During discharge, the battery 12 supplies power to devices such as electric motors included in the high-voltage unit 14. During charging, the battery 12 receives power, for example, via an AC charger or solar charger.

[0012] The first and second current sensors 16a and 16b are attached to the power line 20 to detect the current flowing through the battery 12, respectively. Hereinafter, the current detected using the first current sensor 16a will be referred to as "detected current Ia," and the current detected using the second current sensor 16b will be referred to as "detected current Ib." In the vehicle 10, the current flowing through the battery 12 is monitored by dual monitoring using the detected currents Ia and Ib of these two current sensors 16a and 16b.

[0013] The ECU18 is a computer that includes a processor and a memory device and performs various processes related to the "detection of incorrect assembly of the first and second current sensors 16a and 16b" described later. The memory device stores various information necessary for processing by the processor. The various processes performed by the ECU18 are realized when the processor executes the computer program stored in the memory device. Alternatively, the various processes may be realized by hardware processing using dedicated electronic circuits. In addition, the ECU18 is connected to other sensors (e.g., an accelerator position sensor) along with the current sensors 16a and 16b as various sensors used for the various processes.

[0014] 2. Method for detecting incorrect assembly of current sensors The first and second current sensors 16a and 16b have positive and negative polarities. Therefore, if either current sensor 16a or 16b is incorrectly assembled so that its polarity is reversed, the ECU 18 will detect a completely different current value.

[0015] More specifically, current sensors 16a and 16b are, for example, of the shunt resistor type. Figure 2(A) is a graph showing the relationship between the measured voltage V and the detected current I (Ia or Ib) for current sensors 16a or 16b. In Figure 2(A), the solid line shows the output relationship of current sensors 16a or 16b in a normal state (i.e., with the correct polarity), and the dashed line shows the output relationship of current sensors 16a or 16b when they are incorrectly assembled. From Figure 2(A), it can be seen that if the polarity is reversed from the normal state, the sign of the detected current I (Ia or Ib) value is reversed relative to the normal value when the measured voltage V is the same.

[0016] In this embodiment, the detected current I (Ia or Ib) takes a positive value when the battery 12 is discharging and a negative value when it is charging.

[0017] In the present embodiment, the following method is used to detect the misassembly of the current sensors 16a and 16b. That is, when the battery 12 is discharging or charging, the ECU 18 calculates the slope Ka of the detected current Ia of the first current sensor 16a and the slope Kb of the detected current Ib of the second current sensor 16b. Then, when the calculated slopes Ka and Kb satisfy the relationship of the following formula (1), the ECU 18 determines that there is a possibility of misassembly in either the current sensor 16a or 16b.

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[0018] FIG. 3 is a flowchart showing an example of the processing flow regarding the detection of misassembly of the first and second current sensors 16a and 16b according to the present embodiment. The processing of this flowchart is started, for example, when the system of the vehicle 10 is started (READY on).

[0019] In step S100, the ECU 18 determines whether the battery 12 is discharging or charging has arrived. More specifically, for example, the ECU 18 determines whether the driving mode M1 or the charging mode M2 is selected as the operation mode M of the vehicle 10. The driving mode M1 is the mode when the vehicle 10 is running. The charging mode M2 is the mode when the battery 12 is charged (e.g., charging using an external power source, charging using an in-vehicle solar panel). Whether the driving mode M1 or the charging mode M2 is selected can be determined based on, for example, the user's operation information regarding the selection of the operation mode M. When discharging or charging has arrived (step S100; Yes), the process proceeds to step S102.

[0020] In step S102, the ECU 18 acquires the detected currents Ia and Ib from the current sensors 16a and 16b during a predetermined period (e.g., several seconds) from the start of energizing (discharging or charging) the battery 12. Based on the acquired detected currents Ia and Ib, the ECU 18 calculates the slopes Ka and Kb of the detected currents Ia and Ib during that predetermined period. Here, "slope Ka and Kb" refers to the rate of change of the detected current I over time.

[0021] Figure 2(B) shows the characteristics used to detect misassembly of current sensors 16a and 16b while driving mode M1 is selected. Figure 2(B) is a time chart of the detected current I (Ia or Ib) immediately after the vehicle 10 starts driving. In Figure 2(B), the solid line shows the waveform of the detected current I of a normal (i.e., with the correct polarity) current sensor 16a or 16b, and the dashed line shows the waveform of the detected current I of a current sensor 16a or 16b when it is misassembly. After the current sensors 16a and 16b are assembled into the vehicle 10, the detected current I should behave as follows, regardless of whether it is at the time of shipment of the vehicle 10 or during repair (including when the current sensors 16a or 16b are replaced). In other words, if the current sensors 16a and 16b are assembled correctly, immediately after the vehicle 10 starts moving (for example, immediately after the accelerator pedal is pressed), the slope K (Ka or Kb) (rate of change over time) of the detected current I will be positive (solid line), as shown in Figure 2(B). On the other hand, if the sensors are assembled incorrectly, immediately after the vehicle starts moving, the slope K (rate of change over time) of the detected current I will be negative (dashed line).

[0022] Therefore, if the process proceeds to step S102 while driving mode M1 is being selected, the ECU 18 acquires the detected currents Ia and Ib from the current sensors 16a and 16b during a predetermined period (e.g., a few seconds) from the start of driving the vehicle 10 (e.g., the start of pressing the accelerator pedal). Then, based on the acquired detected currents Ia and Ib, the ECU 18 calculates the respective slopes Ka and Kb of the detected currents Ia and Ib during the predetermined period (in other words, the slopes Ka and Kb immediately after the start of driving the vehicle 10).

[0023] Furthermore, if the battery 12 is charged in charging mode M2 ​​immediately after the current sensors 16a and 16b are assembled, a charging current flows through the battery 12, but no discharge current flows. Therefore, if the assembly is correct, the slope K (Ka or Kb) will be negative, while if the assembly is incorrect, the slope K (Ka or Kb) will be positive.

[0024] Therefore, if the process proceeds to step S102 while charging mode M2 ​​is selected, the ECU 18 acquires the detected currents Ia and Ib for a predetermined period (e.g., a few seconds) from the start of charging. More specifically, this predetermined period is the period in which the charging current increases immediately after the start of charging. Then, based on the acquired detected currents Ia and Ib, the ECU 18 calculates the slopes Ka and Kb, respectively, of the detected currents Ia and Ib during this predetermined period.

[0025] In step S104, following step S102, the ECU18 determines whether the relationship in equation (1) above is satisfied. That is, the ECU18 determines whether the absolute value of the difference obtained by subtracting the slope Kb from the slope Ka, |Ka-Kb|, is substantially equal to the sum of the absolute value of the slope Ka |Ka| and the absolute value of the slope Kb |Kb|, |Ka|+|Kb|.

[0026] In principle, the detected currents Ia and Ib of current sensors 16a and 16b should show the same value. However, in reality, the detected currents Ia and Ib may differ by the amount of the normal error in the sensor output. Consequently, the values ​​of the slopes Ka and Kb may also differ due to the normal errors of current sensors 16a and 16b. In the following explanation, when we say that "the slopes Ka and Kb are equivalent values," we are focusing on the difference between the two due to the normal errors mentioned above.

[0027] When driving begins with current sensors 16a and 16b properly assembled, the slopes Ka and Kb will both be positive and of equivalent value. As a result, the left side of equation (1) will be virtually zero, clearly different from the value on the right side. Similarly, when charging begins with current sensors 16a and 16b properly assembled, the slopes Ka and Kb will both be negative and of equivalent value. In this case as well, the left side of equation (1) will be virtually zero, clearly different from the value on the right side.

[0028] On the other hand, if the vehicle is started to run with the first current sensor 16a incorrectly assembled, the slopes Ka and Kb will be negative and positive, respectively, and their absolute values ​​will be the same. As a result, the left and right sides of equation (1) will be substantially equal. Similarly, if the vehicle is started to run with the other second current sensor 16b incorrectly assembled, the slopes Ka and Kb will be positive and negative, respectively, and their absolute values ​​will be the same. In this case as well, the left and right sides of equation (1) will be substantially equal. Furthermore, although a detailed explanation is omitted here, if charging is started with either the current sensor 16a or 16b incorrectly assembled, the left and right sides of equation (1) will also be substantially equal.

[0029] Based on the above, in this embodiment, if the relationship in equation (1) is satisfied (step S104; Yes), the ECU 18 determines that there is a possibility that either the current sensor 16a or 16b has been incorrectly assembled (step S106). In this case, the ECU 18 may notify the HMI (Human Machine Interface) device such as an in-vehicle device that there is a possibility of incorrect assembly (i.e., an abnormality). On the other hand, if the relationship in equation (1) is not satisfied (step S104; No), the ECU 18 determines that the assembly of the current sensors 16a and 16b is normal (step S108).

[0030] As described above, according to this embodiment, by utilizing the fact that the relationship of equation (1) relating to the slopes Ka and Kb is satisfied during charging or discharging of the battery 12, it becomes possible to detect the possibility of misassembly of either the current sensor 16a or 16b (more specifically, misassembly in which the polarity direction of the current sensor 16a or 16b is reversed). [Explanation of Symbols]

[0031] 10 Vehicle, 12 Battery, 14 High-voltage unit, 16a, 16b Current sensor, 18 ECU, 20, 22 Power line

Claims

[Claim 1] A method by which a computer detects the incorrect assembly of first and second current sensors, which are used to detect the current flowing through a secondary battery mounted on a vehicle, During the discharge or charging of the secondary battery, the slope Ka of the current detected using the first current sensor and the slope Kb of the current detected using the second current sensor are calculated. If the calculated slopes Ka and Kb satisfy the relationship in the following equation, it is determined that there is a possibility of the first and second current sensors being incorrectly assembled. including A method for detecting incorrect assembly of a current sensor. [Math 1]

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