Method for detecting incorrect assembly of current sensors

Abstract

This system properly detects incorrect assembly of current sensors used to detect the current flowing through a secondary battery. [Solution] The method for detecting incorrect assembly of a current sensor is a method in which a computer detects incorrect assembly of a current sensor used to detect the current flowing through a secondary battery mounted on a vehicle. The method includes detecting the current using the current sensor when the vehicle's operating mode is either a driving mode in which the vehicle is driven or a charging mode in which the secondary battery is charged, and determining whether or not there is a possibility of incorrect assembly based on the slope of the detected current.

Description

Technical Field

[0001] The present disclosure relates to detection of misassembly of a current sensor for detecting a current 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

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, since the 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 the 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 a current sensor according to this disclosure is a method by which a computer detects misassembly of a current sensor used to detect the current flowing through a secondary battery mounted in a vehicle. The method includes detecting a current using the current sensor when the vehicle's operating mode is either a driving mode in which the vehicle is driven or a charging mode in which the secondary battery is charged, and determining whether or not there is a possibility of misassembly based on the slope of the detected current. [Effects of the Invention]

[0006] According to this disclosure, it is possible to detect the possibility of a current sensor being misassembled by utilizing the gradient of the current detected using the current sensor when the vehicle's operating mode is either driving mode or charging mode. [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 a current sensor, and (B) is a diagram showing the characteristics used to detect incorrect assembly of the current sensor. [Figure 3] This flowchart shows an example of the processing flow for detecting incorrect assembly of a current sensor 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, a current sensor 16, 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. The current sensor 16 is attached to the power line 20 to detect the current flowing through the battery 12. Hereinafter, the current detected using the current sensor 16 will be referred to as the "detected current I".

[0012] 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 current sensor 16" 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, these 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 sensor 16 as various sensors used for the various processes.

[0013] 2. Method for detecting incorrect assembly of current sensors The current sensor 16 has positive and negative polarity. Therefore, if the current sensor 16 is incorrectly assembled so that its polarity is reversed, the ECU 18 will detect a completely different current value.

[0014] More specifically, the current sensor 16 is, for example, a shunt resistor type. Figure 2(A) is a graph showing the relationship between the measured voltage V and the detected current I for the current sensor 16. In Figure 2(A), the solid line shows the output relationship of the current sensor 16 when it is functioning correctly (i.e., with the correct polarity), and the dashed line shows the output relationship of the current sensor 16 when it is incorrectly assembled. From Figure 2(A), it can be seen that if the polarity is reversed from the correct direction, the sign of the detected current I will be reversed relative to the correct value when the measured voltage V is the same.

[0015] In this embodiment, the detected current I takes a positive value when the battery 12 is discharging and a negative value when it is charging.

[0016] In this embodiment, the following method is used to detect incorrect assembly of the current sensor 16. Specifically, when the operating mode M of the vehicle 10 is driving mode M1 or charging mode M2, the ECU 18 uses the current sensor 16 to detect the current (in other words, it obtains the detected current I). Then, the ECU 18 determines whether or not there is a possibility of incorrect assembly based on the slope of the detected current I (slopes K1 and K2 described later).

[0017] Figure 3 is a flowchart showing an example of the processing flow for detecting incorrect assembly of the current sensor 16 according to this embodiment. The processing in this flowchart starts, for example, when the vehicle 10 system is started (READY ON).

[0018] In step S100, the ECU 18 determines whether the operating mode M of the vehicle 10 is driving mode M1 or charging mode M2. Driving mode M1 is the mode in which the vehicle 10 is driven. Charging mode M2 ​​is the mode in which the battery 12 is charged (e.g., charging using an external power source, charging using an on-board solar panel). For example, the selection of the operating mode M is made by the user of the vehicle 10. The ECU 18 can then make the determination in step S100 based on, for example, the user's operation information regarding the selection of the operating mode M.

[0019] When it is determined in step S100 that the driving mode M1 is selected, the ECU 18 determines whether the accelerator opening is greater than 0 (that is, whether the accelerator pedal has been depressed), for example, using an accelerator position sensor (step S102). If the depression of the accelerator pedal is not detected (step S102; No), that is, if the running of the vehicle 10 has not started, the process returns to the start. As a result, the determinations in steps S100 and S102 are repeatedly executed. On the other hand, if the depression of the accelerator pedal is detected (step S102; Yes), the process proceeds to step S104. In the example of the vehicle 10 having an automatic start function, in step S102, the ECU 18 may determine whether the vehicle 10 has started running by the automatic start function.

[0020] In step S104, the ECU 18 acquires the detected current I of the current sensor 16 during a predetermined period (e.g., several seconds) from the start of the depression of the accelerator pedal. Then, based on the acquired detected current I, the ECU 18 calculates the slope K1 of the detected current I during the predetermined period (in other words, the slope K1 immediately after the start of the running of the vehicle 10). The "slope K1" here is the time change rate of the detected current I during the driving mode M1, as supplemented by referring to FIG. 2(B).

[0021] FIG. 2(B) is a diagram showing the characteristics used to detect a misassembly of the current sensor 16. FIG. 2(B) is a time chart of the detected current I immediately after the start of travel of the vehicle 10. In FIG. 2(B), the solid line indicates the waveform of the detected current I of the normal (i.e., the polarity direction is normal) current sensor 16, and the broken line indicates the waveform of the detected current I of the current sensor 16 when a misassembly has occurred. After the current sensor 16 is assembled to the vehicle 10, regardless of whether it is at the time of shipment of the vehicle 10 or at the time of repair (including when the current sensor 16 is replaced), the detected current I should exhibit the following behavior. That is, if the assembly of the current sensor 16 is normal, immediately after the start of travel of the vehicle 10 (for example, immediately after the accelerator pedal is depressed), the slope K1 (rate of change with time) of the detected current I becomes positive as shown in FIG. 2(B) (solid line). On the other hand, when a misassembly has occurred, immediately after the start of travel, the slope K1 (rate of change with time) of the detected current I becomes negative (broken line).

[0022] In step S106 following step S104, the ECU 18 determines whether the calculated slope K1 is smaller than a predetermined threshold value Z. Here, the threshold value Z is set to a value smaller than 0. The reason for this is that if the threshold value Z is set to 0, when a negative slope K1 due to the normal error of the output of the current sensor 16 is calculated, it will be determined that the slope K1 is smaller than the threshold value Z even if the assembly is normal. More specifically, in view of this point, the threshold value Z may be set to a value larger on the negative side by a predetermined amount (e.g., a value corresponding to -5 LSB) than the maximum value of the negative slope K1 that can occur due to the normal error.

[0023] When the slope K1 in the travel mode M1 is greater than or equal to the threshold value Z (step S106; No), the process proceeds to step S108. In step S108, the ECU 18 determines that the assembly of the current sensor 16 is normal.

[0024] On the other hand, if the slope K1 is less than the threshold Z (step S106; Yes), the process proceeds to step S110. In step S110, the ECU 18 determines that there is a possibility that the current sensor 16 has been incorrectly assembled. 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).

[0025] On the other hand, if it is determined in step S100 that charging mode M2 ​​is selected, the ECU 18 acquires the detected current I 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. Based on the acquired detected current I, the ECU 18 calculates the slope K2 (rate of change over time) of the detected current I during this predetermined period. Here, if the battery 12 is charged immediately after the current sensor 16 is assembled, a charging current flows through the battery 12, and no discharge current flows. Therefore, if the assembly is normal, the slope K2 will be negative, while if the assembly is incorrect, the slope K2 will be positive.

[0026] In step S114, following step S112, the ECU 18 determines whether the calculated slope K2 is greater than a predetermined threshold Y. Here, the threshold Y is set to a value greater than 0. The reason for this is that if the threshold Z is set to 0, and a positive slope K2 is calculated due to the normal error of the output of the current sensor 16, the slope K2 will be determined to be greater than the threshold Y even if the assembly is normal. More specifically, in light of this point, the threshold Y may be set to a value that is a predetermined amount greater in the positive direction than the maximum value of the positive slope K2 that can occur due to the normal error (e.g., a value equivalent to 5 LSB).

[0027] If the tilt K2 in charging mode M2 ​​is less than or equal to the threshold Y (step S114; No), the ECU 18 determines that the assembly of the current sensor 16 is normal (step S108). On the other hand, if the tilt K2 is greater than the threshold Y (step S114; Yes), the ECU 18 determines that there is a possibility that the current sensor 16 has been incorrectly assembled (step S110). In this case as well, the ECU 18 may also notify the HMI device such as the in-vehicle equipment that there is a possibility of incorrect assembly (i.e., an abnormality).

[0028] As described above, according to this embodiment, it is possible to detect the possibility of incorrect assembly of the current sensor 16 (more specifically, incorrect assembly with the polarity of the current sensor 16 reversed) by utilizing the slope K1 or K2 of the detected current I of the current sensor 16 when the operating mode M of the vehicle 10 is driving mode M1 or charging mode M2. [Explanation of Symbols]

[0029] 10 Vehicle, 12 Battery, 14 High-voltage unit, 16 Current sensor, 18 ECU, 20, 22 Power lines

Claims

[Claim 1] A method by which a computer detects the incorrect installation of a current sensor used to detect the current flowing through a secondary battery installed in a vehicle, When the operating mode of the vehicle is either a driving mode in which the vehicle is driven or a charging mode in which the secondary battery is charged, the current is detected using the current sensor. Based on the detected slope of the current, it is determined whether or not there is a possibility of the incorrect assembly, including A method for detecting incorrect assembly of a current sensor.

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