Charging device

Abstract

To reduce an error of SOC during charging.SOLUTION: A control device for a charging device includes: one or more processors; and one or more memories connected to the processor(s). Each processor executes processing including: interrupting charging of an on-vehicle battery at a predetermined timing during charging of the on-vehicle battery; discharging at least part of power of the on-vehicle battery from the on-vehicle battery when the charging of the on-vehicle battery is interrupted; measuring a voltage of the on-vehicle battery after discharge of the on-vehicle battery; and deriving an SOC of the on-vehicle battery on the basis of the measured voltage of the on-vehicle battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charging device. [Background technology]

[0002] For example, Patent Document 1 discloses a technique relating to charging control of an in-vehicle battery. Patent Document 1 shows that polarization occurs in the in-vehicle battery when the in-vehicle battery is charged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-185259 Summary of the Invention [Problem to be solved by the invention]

[0004] The SOC (State of Charge) of an in-vehicle battery is calculated based on, for example, a measured voltage of the in-vehicle battery. However, if polarization occurs in the in-vehicle battery, an error may occur between the SOC calculated based on the measured voltage and the actual SOC.

[0005] Therefore, an object of the present invention is to provide a charging device that can reduce errors in SOC during charging. [Means for solving the problem]

[0006] In order to solve the above problem, a charging device according to one embodiment of the present invention comprises: a charging port electrically connectable to a power source external to the vehicle; an in-vehicle battery electrically connectable to the charging port; a control device that charges the vehicle battery with power supplied through the charging port; Equipped with The control device one or more processors; one or more memories coupled to said processor; and The processor: setting a predetermined timing for interrupting charging of the vehicle-mounted battery based on a temperature of the vehicle-mounted battery at the start of charging; The vehicle battery is charging , set Suspending charging of the vehicle battery at a predetermined timing; When charging of the vehicle battery is interrupted, at least a portion of the power of the vehicle battery is discharged from the vehicle battery. measuring the voltage of the vehicle battery after discharging the vehicle battery; Deriving a SOC of the vehicle battery based on the measured voltage of the vehicle battery; Execute the process including. In order to solve the above problem, a charging device according to one embodiment of the present invention comprises: a charging port electrically connectable to a power source external to the vehicle; an in-vehicle battery electrically connectable to the charging port; a control device that charges the vehicle battery with power supplied through the charging port; Equipped with The control device one or more processors; one or more memories coupled to said processor; and The processor: interrupting charging of the vehicle-mounted battery at a predetermined timing during charging of the vehicle-mounted battery; deriving a target value of an integrated discharge current amount obtained by integrating a discharge current of the vehicle-mounted battery over time based on an integrated charge current amount obtained by integrating a charge current of the vehicle-mounted battery over time and a temperature of the vehicle-mounted battery at the start of discharge; When charging of the vehicle battery is interrupted, so that the actual integrated amount of discharge current due to discharge is equal to or greater than the derived target value of the integrated amount of discharge current. Discharging at least a portion of the power of the vehicle battery from the vehicle battery; measuring the voltage of the vehicle battery after discharging the vehicle battery; Deriving a SOC of the vehicle battery based on the measured voltage of the vehicle battery; Execute the process including. In order to solve the above problem, a charging device according to one embodiment of the present invention comprises: a charging port electrically connectable to a power source external to the vehicle; an in-vehicle battery electrically connectable to the charging port; a control device that charges the vehicle battery with power supplied through the charging port; Equipped with The control device one or more processors; one or more memories coupled to said processor; and The processor: deriving a SOC of the vehicle-mounted battery based on an integrated charging current amount obtained by integrating a charging current of the vehicle-mounted battery over time while the vehicle-mounted battery is being charged; The vehicle battery is charging The conditions for interrupting charging at interrupting charging of the vehicle battery at a timing; If the SOC of the vehicle battery is equal to or greater than a predetermined threshold when the condition for interrupting charging is met, When charging of the vehicle battery is interrupted, at least a part of the power of the vehicle battery is discharged from the vehicle battery. 、 measuring the voltage of the vehicle battery after discharging the vehicle battery; If the SOC of the vehicle battery is less than a predetermined threshold when the condition for interrupting charging is met, the vehicle battery is not discharged, but is brought into a non-powered state, and a voltage of the vehicle battery is measured; Deriving a SOC of the vehicle battery based on the measured voltage of the vehicle battery; Execute the process including. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce errors in SOC during charging. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a charging system according to this embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the behavior of an in-vehicle battery immediately after the start of charging. [Figure 3] FIG. 3 is a diagram showing an example of the behavior of an in-vehicle battery during charging. [Figure 4]FIG. 4 is a diagram showing an example of the time change of current and the time change of measured voltage during charging. [Figure 5] FIG. 5 is a diagram illustrating an example of deriving the SOC from the measured voltage. [Figure 6] FIG. 6 is a diagram illustrating forced charging. [Figure 7] FIG. 7 is a time chart illustrating an example of the operation of the control device from the start to the end of charging. [Figure 8] FIG. 8 is a functional block diagram of the control device. [Figure 9] FIG. 9 is a flowchart illustrating the flow of the operation of the charging control unit. [Figure 10] FIG. 10 is a flowchart illustrating the flow of the high SOC region processing. [Figure 11] FIG. 11 is a flowchart illustrating the flow of the low SOC region processing. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0010] 1 is a schematic diagram showing the configuration of a charging system 1 according to this embodiment. The charging system 1 includes a power supply facility 10 and a vehicle 12. The vehicle 12 is an electric vehicle or a hybrid vehicle. A charging device 14 according to this embodiment is applied to the vehicle 12 and charges an on-board battery 40, which will be described later.

[0011] The power supply equipment 10 includes a power conversion device 20, a charging cable 22, and a charging connector 24. The power conversion device 20 is electrically connected to an electric power system 26. The electric power system 26 is an example of a power source external to the vehicle 12. A first end of the two ends of the charging cable 22 is connected to the power conversion device 20. The charging connector 24 is provided at a second end of the two ends of the charging cable 22. The charging connector 24 is connectable to a charging port 44 of the vehicle 12, as will be described later.

[0012] The power conversion device 20 converts power supplied from the power grid 26 and supplies the converted power to the charging connector 24. When the charging connector 24 is connected to the charging port 44, the power conversion device 20 can supply power to the vehicle 12 through the charging connector 24. For example, the power conversion device 20 converts commercial AC power from the power grid 26 into DC power and supplies the DC power to the vehicle 12. The power conversion device 20 may also convert the commercial AC power from the power grid into AC power of a predetermined frequency and supply the AC power to the vehicle 12. In this case, the vehicle 12 may be provided with a device that converts the supplied AC power into DC power. When the charging connector 24 is connected to the charging port 44, the power conversion device 20 can receive power from the vehicle 12 through the charging connector 24. The power conversion device 20 can convert the power received from the vehicle 12 and supply the converted power to the power grid 26.

[0013] The power supply equipment 10 includes a control device 30. The control device 30 includes one or more processors 32 and one or more memories 34 connected to the processor 32. The memory 34 includes a ROM in which programs and the like are stored and a RAM as a work area. The processor 32 of the control device 30 controls the entire power supply equipment 10 in cooperation with the programs stored in the memory 34. For example, the processor 32 executes processing to control the power conversion device 20. The control device 30 can also communicate with the vehicle 12 via the charging cable 22 and the charging connector 24. The control device 30 can control the power conversion device 20 in accordance with various information received from the vehicle 12.

[0014] The vehicle 12 is equipped with an on-board battery 40. The on-board battery 40 is, for example, a secondary battery such as a lithium-ion battery. The on-board battery 40 supplies power to a motor generator, which is a drive source for the vehicle 12. The motor generator drives the wheels of the vehicle 12. The motor generator also generates power when the vehicle 12 decelerates. The on-board battery 40 is charged with the power generated by the motor generator.

[0015] The vehicle 12 includes a control box 42 and a charging port 44. The charging port 44 is connectable to the charging connector 24. The control box 42 has a first switch 50 and a second switch 52. The first switch 50 and the second switch 52 are switches that can turn an electrical connection on and off, such as a circuit breaker, a relay, or a semiconductor switch.

[0016] A first contact of the first switch 50 is connected to the input / output terminal of the vehicle battery 40. A second contact of the first switch 50 is connected to the charging port 44. The first switch 50 turns the electrical connection between the charging port 44 and the vehicle battery 40 on and off.

[0017] When charging connector 24 is connected to charging port 44, vehicle 12 can receive power from power grid 26 through power supply equipment 10. In this state, when first switch 50 is turned on, the received power is supplied to on-board battery 40 through charging port 44 and first switch 50, and on-board battery 40 is charged.

[0018] A first contact of the second switch 52 is connected to an input / output terminal of the vehicle battery 40 and a first contact of the first switch 50 connected to the vehicle battery 40. A second contact of the second switch 52 is connected to an electrical load 60 mounted on the vehicle 12. The electrical load 60 is, for example, various electrical equipment such as an in-vehicle air conditioner or a DC-DC converter. Note that the electrical load 60 is not limited to the electrical equipment exemplified above, but may be any electrical equipment mounted on the vehicle 12. Furthermore, the number of electrical loads 60 is not limited to one, and there may be multiple electrical loads 60. The second switch 52 turns on and off the electrical connection between the vehicle battery 40 and the electrical load 60.

[0019] When the first switch 50 is turned off and the second switch 52 is turned on, the vehicle battery 40 supplies power to the electric load 60 through the second switch 52. That is, the electric load 60 consumes the power discharged from the vehicle battery 40.

[0020] When both the first switch 50 and the second switch 52 are turned off, the vehicle battery 40 enters a non-powered state. The non-powered state is a state in which the current at the input / output terminals of the vehicle battery 40 is zero, and no current flows out of or into the vehicle battery 40.

[0021] The vehicle 12 includes a control device 70. The control device 70 includes one or more processors 72 and one or more memories 74 connected to the processor 72. The memory 74 includes a ROM storing programs and the like and a RAM serving as a work area. The processor 72 of the control device 70 controls the entire vehicle 12 in cooperation with the programs stored in the memory 74. For example, the processor 72 executes processing related to charging the on-board battery 40 with power received from the power supply equipment 10. The control device 70 can communicate with the power supply equipment 10 through the charging port 44. The control device 70 can indirectly control the power conversion device 20 via the control device 30 by communicating with the control device 30 of the power supply equipment 10. In other words, the control device 70 can substantially control charging of the on-board battery 40 by the power supply equipment 10. The control device 70 can also control the on / off of the first switch 50 and the second switch 52. The processing executed by the processor 72 of the control device 70 will be described in detail later.

[0022] The vehicle 12 is equipped with a voltage sensor 80, a current sensor 82, and a temperature sensor 84. The voltage sensor 80 detects the voltage at the input / output terminals of the vehicle battery 40. The current sensor 82 detects the current at the input / output terminals of the vehicle battery 40. The temperature sensor 84 detects the temperature of the vehicle battery 40.

[0023] 2 is a diagram showing an example of the behavior of the vehicle-mounted battery 40 immediately after the start of charging. The vehicle-mounted battery 40 has a housing 90, a positive electrode member 92, and a negative electrode member 94. The positive electrode member 92 and the negative electrode member 94 are housed in the housing 90. The housing 90 also contains an electrolyte.

[0024] The positive electrode member 92 is electrically connected to the positive terminal of the charging port 44 through the input / output terminals of the vehicle battery 40. The negative electrode member 94 is electrically connected to the negative terminal of the charging port 44 through the input / output terminals of the vehicle battery 40. Note that the first switch 50 is omitted in FIG. 2. When the charging port 44 is connected to the charging connector 24, the positive and negative terminals of the charging port 44 are each connected to the power grid 26, which is a power source, through the power feeding equipment 10. That is, a charging current for charging the vehicle battery 40 flows through the charging port 44 to the positive electrode member 92 and negative electrode member 94 of the vehicle battery 40.

[0025] A circle 96 in FIG. 2 illustrates electrons in the vehicle-mounted battery 40, and an arrow 98 in FIG. 2 illustrates the direction of electron movement. When a charging current flows through the vehicle-mounted battery 40, electrons in the positive electrode member 92 flow out into the electrolyte. Electrons in the electrolyte move toward the negative electrode member 94. Electrons that reach the negative electrode member 94 enter the negative electrode member 94. Electrons in the negative electrode member 94 move to the positive electrode member 92 through the negative electrode input / output terminal of the vehicle-mounted battery 40, the charging port 44 connected to the power source, and the positive electrode input / output terminal of the vehicle-mounted battery 40. The vehicle-mounted battery 40 is charged by this movement of electrons.

[0026] The voltage sensor 80 is connected between the negative input / output terminal of the vehicle battery 40 and the positive input / output terminal of the vehicle battery 40. The voltage sensor 80 measures the voltage between the negative input / output terminal and the positive input / output terminal. Hereinafter, the voltage measured by the voltage sensor 80 may be referred to as the measured voltage.

[0027] Immediately after charging begins, electrons in the vehicle battery 40 move smoothly without any hindrance, as shown in Figure 2. When electrons in the vehicle battery 40 are moving smoothly in this manner, the voltage between the negative electrode member 94 and the positive electrode member 92 of the vehicle battery 40 can be measured properly by the voltage sensor 80.

[0028] FIG. 3 is a diagram illustrating an example of the behavior of the in-vehicle battery 40 during charging. As time passes from the start of charging, as shown in FIG. 3, an electron imbalance occurs, in which electrons do not all enter the negative electrode member 94 and instead accumulate in the surface layer of the negative electrode member 94. When such an electron imbalance occurs, the potential of the surface layer of the negative electrode member 94 decreases due to the electrons accumulated in the surface layer of the negative electrode member 94. This causes a pseudo-potential difference to occur between the surface layer of the positive electrode member 92 and the surface layer of the negative electrode member 94. Hereinafter, this pseudo-potential difference caused by such an electron imbalance may be referred to as a pseudo-potential difference. The phenomenon in which such a pseudo-potential difference occurs may be referred to as polarization. For this reason, the pseudo-potential difference may be referred to as a polarization voltage. The pseudo-potential difference becomes more pronounced as the charging current increases during charging.

[0029] Taking the above polarization into consideration, the theoretical formula for the measured voltage of the vehicle battery 40 is given by the following formula (1). V = OCV - I × R + Vy (1)

[0030] In equation (1), "V" is the measured voltage, "OCV" is the base voltage, "I" is the current at the input / output terminals of the vehicle battery 40, "R" is the internal resistance of the vehicle battery 40, and "Vy" is the voltage due to polarization, i.e., the pseudo-potential difference. The base voltage is the original voltage between the negative electrode member 94 and the positive electrode member 92 when the vehicle battery 40 is in a non-energized state. As shown in equation (1) above, the measured voltage is the base voltage plus the pseudo-potential difference.

[0031] Figure 4 is a diagram showing an example of the change in current and the change in measured voltage over time during charging. For example, assume that charging starts at time T1 in Figure 4 and ends at time T2. Note that the discharge current flowing out of the vehicle battery 40 is shown as a positive value, and the charge current flowing into the vehicle battery 40 is shown as a negative value.

[0032] The dashed-dotted line A1 in Figure 4 is an example of "-I x R" in the above formula (1). Note that since the charging current is shown as a negative value, "-I x R" is a positive value. The dashed-two-dotted line A2 in Figure 4 is an example of "OCV - I x R" in the above formula (1). The solid line A3 in Figure 4 is an example of "OCV - I x R + Vy" in the above formula (1), i.e., the measured voltage "V." Furthermore, the arrow A4 indicating the difference between the dashed-two-dotted line A2 and the dashed-two-dotted line A1 corresponds to the base voltage "OCV." The arrow A5 indicating the difference between the solid line A3 and the dashed-two-dotted line A2 corresponds to the pseudo-potential difference "Vy."

[0033] When charging is performed at a constant current, the measured voltage includes a constant voltage according to the charging current, as shown by the dashed line A1. Because the charging current and internal resistance are known values, it is easy to derive the voltage by subtracting the value of "-I x R" shown by the dashed line A1 from the measured voltage.

[0034] As shown by the two-dot chain line A2, the base voltage gradually increases as charging continues. This increase in the base voltage corresponds to the actual increase in voltage of the vehicle battery 40 due to charging.

[0035] Furthermore, as shown by the solid line A3, the pseudo potential difference also increases as charging continues. The measured voltage is the sum of the increase in the base voltage and the increase in the pseudo potential difference. For example, suppose charging is terminated when the measured voltage reaches a predetermined upper limit voltage shown by the dashed line A6. As described above, since the increase in the pseudo potential difference is also added to the measured voltage, even if the measured voltage reaches the upper limit voltage, the actual voltage due to charging has not reached the upper limit voltage.

[0036] Furthermore, when charging is terminated at timing T2, the vehicle battery 40 is placed in a non-powered state. When the vehicle battery 40 is placed in a non-powered state, "-I×R" becomes zero. Furthermore, as the non-powered state continues, the imbalance of electrons in the vehicle battery 40, i.e., polarization, gradually disappears. This causes the pseudo-potential difference to decrease, and the measured voltage gradually decreases, as indicated by the solid line A3 in FIG. 4. Then, as the non-powered state continues for a long time, the polarization is completely eliminated, and the measured voltage settles to a constant value. As indicated by the arrow A7 in FIG. 4, the measured voltage when it settles to a constant value corresponds to the base voltage that increased from the start of charging to the end of charging. The time it takes for the measured voltage to settle to a constant value is, for example, 20 minutes, but depends on the specifications of the vehicle battery 40, the charging current during charging, the temperature of the vehicle battery 40, and other factors.

[0037] The control device 70 sequentially acquires the measured voltage from the voltage sensor 80 during charging, and derives the SOC based on the acquired measured voltage. The SOC is an index that indicates the state of charge of the vehicle battery 40, and is expressed, for example, as a percentage of the current charge capacity relative to the charge capacity when fully charged.

[0038] However, since the measured voltage includes a pseudo-potential difference due to polarization, the derived SOC includes an error from the actual SOC. Furthermore, since the pseudo-potential difference varies depending on the state of the vehicle battery 40, such as the charging current or the temperature of the vehicle battery 40, it is difficult to derive the pseudo-potential difference itself.

[0039] FIG. 5 illustrates an example of deriving the SOC from the measured voltage. In FIG. 5, the solid line A10 represents the relationship between the measured voltage and the SOC when a relatively large current is flowing through the vehicle battery 40 and significant polarization is occurring. The dashed-dotted line A11 represents the relationship between the measured voltage and the SOC when a small current is flowing through the vehicle battery 40. That is, the dashed-dotted line A11 corresponds to a case where the vehicle battery 40 is energized but not polarized, or where polarization is present but only a small pseudo-potential difference is generated that is deemed to be non-existent. The dashed-dotted line A12 represents the relationship between the measured voltage and the SOC when the vehicle battery 40 is not polarized and is not energized. The solid line A10, the dashed-dotted line A11, and the dashed-dotted line A12 generally indicate that the SOC increases as the measured voltage increases.

[0040] At least the curve of the two-dot chain line A12 is pre-stored in the memory 74 of the control device 70. The curve of the one-dot chain line A11 is higher in measured voltage than the curve of the two-dot chain line A12 by "-I x R" in the above formula (1). Therefore, the curve of the one-dot chain line A11 can be derived based on the curve of the two-dot chain line A12 that is pre-stored. Note that the curve of the one-dot chain line A11 may also be stored in the memory 74.

[0041] The solid line A10 corresponds to an example of an actual measured voltage during charging. However, since the measured voltage includes a pseudo-potential difference, it is difficult to prepare the curve of the solid line A10 in advance.

[0042] Furthermore, SOC "C10" in FIG. 5 indicates a predetermined threshold value for SOC. This threshold value separates a low SOC region where the SOC is below the threshold value from a high SOC region where the SOC is equal to or greater than the threshold value. In the low SOC region, the solid line A10 and the dashed-dotted line A11 are close to each other. That is, in the low SOC region, the influence of polarization is small and the pseudo-potential difference is relatively small. On the other hand, in the high SOC region, the difference between the solid line A10 and the dashed-dotted line A11 is relatively large, and the difference between the solid line A10 and the dashed-dotted line A11 increases as the SOC increases. In this way, this threshold value separates a low SOC region where the influence of polarization is relatively small from a high SOC region where the influence of polarization is relatively large. The threshold value is, for example, 50%, but varies depending on the state of the vehicle battery 40, such as the charging current or the temperature of the vehicle battery 40.

[0043] As described above, the control device 70 can determine the curve of the dashed-dotted line A11 based on the previously stored two-dot-dotted line A12, but cannot determine the curve of the solid line A10. Assume that the current measured voltage during charging is, for example, measured voltage V11. In this case, the control device 70 derives, as the current SOC, the SOC "C11" corresponding to point P11 where the measured voltage becomes measured voltage V11 on the determined curve of the dashed-dotted line A11.

[0044] However, the measured voltage V11 actually contains a pseudo-potential difference. Therefore, the actual SOC is only charged to the SOC "C12" corresponding to point P12 on the curve of the solid line A10 where the measured voltage becomes the measured voltage V11. As such, an error occurs in the derived SOC due to the influence of polarization, and even though the actual SOC is only "C12," it is erroneously determined that the battery is charged to the higher SOC "C11." Therefore, if charging were to be terminated at this point, the battery would only be charged to the actual SOC "C12."

[0045] Furthermore, in the high SOC region, the influence of polarization is large, so the error in the derived SOC becomes larger than in the low SOC region. If the error in the SOC is large, charging may end at an SOC lower than the target SOC.

[0046] For example, suppose the control device 70 terminates charging when the measured voltage reaches a predetermined upper limit voltage, V13. In this case, the control device 70 derives the current SOC as SOC "C13," which corresponds to point P13 on the curve indicated by the dashed-dotted line A11, where the measured voltage reaches V13. However, in reality, the battery has only been charged up to SOC "C14," which corresponds to point P14 on the curve indicated by the solid line A10, where the measured voltage reaches V13. Thus, although the intention is to terminate charging at SOC "C13," charging actually terminates at SOC "C14," which is lower than SOC "C13."

[0047] The control device 70 may perform forced charging after the end of charging to prevent the actual SOC from decreasing after the end of charging. Here, for the sake of convenience, to distinguish between forced charging and charging before forced charging, the general charging before forced charging may be referred to as main charging. Forced charging has a smaller absolute value of the charging current than main charging.

[0048] FIG. 6 is a diagram illustrating forced charging. In the example of FIG. 6, main charging begins at time T20 and ends at time T21 when the measured voltage reaches a predetermined upper limit voltage, measured voltage V20. When main charging ends, the vehicle battery 40 is placed in a non-powered state from time T21 until time T22, a predetermined time later. When placed in a non-powered state, polarization gradually disappears, and the measured voltage gradually decreases as polarization disappears. For example, at time T22, the measured voltage decreases to measured voltage V21, which is lower than measured voltage V20. The predetermined time for which the non-powered state is maintained is set arbitrarily, taking into account the time it takes for polarization to disappear and the final termination timing of charging after forced charging.

[0049] Also, the actual SOC at timing T21 when the main charging is completed is, for example, SOC “C20.” While the no-power state is maintained, the actual SOC is maintained at approximately SOC “C20.”

[0050] At time T22, a predetermined time after the power-off state, the control device 70 starts forced charging. Like main charging, polarization can occur during forced charging. When forced charging starts, the measured voltage rises in accordance with the forced charging current. Consequently, the actual SOC also rises in accordance with the rise in measured voltage.

[0051] At timing T23 when the measured voltage reaches measured voltage V20 again, the control device 70 ends the forced charging and puts the vehicle battery 40 into a non-powered state. This gradually eliminates the polarization caused by the forced charging, and the measured voltage gradually decreases as the polarization is eliminated, and once the polarization is eliminated, the measured voltage stabilizes.

[0052] Due to the forced charging, the actual SOC at time T23 when the forced charging ends becomes, for example, SOC "C21" which is higher than SOC "C20." In this way, by performing forced charging, it is possible to prevent the SOC after the end of the entire charging process, including main charging and forced charging, from decreasing from the target SOC.

[0053] However, even if forced charging is performed, the measured voltage increases due to polarization during main charging, and the measured voltage reaches measured voltage V20 early. This increases the error between the SOC based on the measured voltage and the actual SOC, and main charging may be terminated before the actual SOC becomes sufficiently high.

[0054] Furthermore, setting the non-powered period between main charging and forced charging long enough to completely eliminate the polarization during main charging can delay the timing of the overall charging termination. Therefore, if the non-powered period is set too short, forced charging may be performed before the polarization during main charging is completely eliminated. This can cause the measured voltage V20 to be reached prematurely during forced charging due to the effects of polarization. This can result in forced charging being terminated before the SOC has sufficiently increased, potentially resulting in insufficient suppression of SOC decline at the end of charging. For example, as shown by arrow A20 in Figure 6, the difference between the target SOC "C22" at the end of overall charging and the actual SOC "C21" may not be sufficiently narrow.

[0055] In consideration of these, the control device 70 of this embodiment forcibly eliminates polarization during main charging, and calibrates the measured voltage to a measured voltage in which the pseudo potential difference has been eliminated.

[0056] More specifically, the control device 70 interrupts the main charging at a predetermined timing, and during the interruption, discharges at least a portion of the power of the vehicle battery 40. When the vehicle battery 40 is discharged, the electrons in the vehicle battery 40 move in the opposite direction to that during charging, thereby eliminating the imbalance of electrons in the vehicle battery 40. As a result, polarization is quickly eliminated, and the pseudo-potential difference can be quickly reduced.

[0057] After discharging, the control device 70 de-energizes the vehicle battery 40 and measures the voltage in this de-energized state. Because the voltage is measured in a de-polarized state, it is calibrated to an appropriate measured voltage with substantially no pseudo-potential difference. Note that "substantially no pseudo-potential difference" may also include a case where a pseudo-potential difference is small enough to be considered non-existent.

[0058] The control device 70 then derives the SOC based on the calibrated measured voltage. Because the calibrated measured voltage is substantially free of pseudo-potential differences, the SOC derived based on the measured voltage is substantially equal to the actual SOC. For example, in the example of FIG. 5, the measured voltage immediately before discharge is V11. In this example, when discharge is performed and the voltage is measured in the power-off state after discharge, a measured voltage V15 lower than V11 is obtained. The control device 70 derives the SOC corresponding to point P15 on the curve of the two-dot chain line A12 for the power-off state, where the measured voltage becomes V15, as the current SOC. In this way, the control device 70 can derive an SOC "C12" substantially equal to the actual SOC "C12" immediately before discharge. Therefore, the control device 70 can suppress SOC errors during charging.

[0059] Furthermore, because the control device 70 calibrates the measured voltage during main charging, it is possible to prevent the measured voltage from becoming excessively high and to prevent the measured voltage from reaching a predetermined upper limit voltage too quickly, thereby enabling the control device 70 to reduce the difference between the target SOC and the actual SOC at the end of main charging.

[0060] Furthermore, the control device 70 can further reduce the difference between the target SOC and the actual SOC at the end of the entire charging by performing forced charging after the main charging in addition to calibrating the measured voltage by discharging.

[0061] 7 is a time chart illustrating an example of the operation of the control device 70 from the start to the end of charging. In the example of FIG. 7, main charging starts at timing T30. The SOC at the start of main charging is lower than SOC "C30," which is a threshold that separates the low SOC region from the high SOC region, and belongs to the low SOC region.

[0062] At time T31 after time T30, a predetermined interruption condition is met. The interruption condition is, for example, when the integrated amount of charging current, calculated by integrating the charging current over time from time T30 to time T31 when the interruption condition is met, reaches a predetermined value. At time T31 when this interruption condition is met, the control device 70 temporarily interrupts main charging.

[0063] Assume that the SOC at time T31 when the interruption condition is met is less than the threshold SOC "C30." In this case, the control device 70 puts the vehicle battery 40 into a non-powered state and maintains this non-powered state for a predetermined time. This reduces the pseudo-potential difference that occurs during the period from time T30 to time T31. The predetermined time can be set arbitrarily, taking into account factors such as the amount of accumulated charging current from time T30 to time T31.

[0064] At timing T32 when the power-off state has been maintained for a predetermined time, the control device 70 measures the voltage of the vehicle battery 40 and derives the SOC based on the measured voltage. The control device 70 then resumes main charging. When main charging is resumed, the measured voltage and SOC increase.

[0065] At time T34 after time T32, a predetermined interruption condition is met. For example, the interruption condition is met when the integrated amount of charging current from time T32 to time T34 reaches a predetermined value. At time T34 when this interruption condition is met, the control device 70 temporarily interrupts main charging.

[0066] Here, timing T33 between timing T32 and timing T34 is the timing when the SOC reaches SOC "C30." Therefore, the SOC at timing T34 is equal to or higher than SOC "C30." In this case, the control device 70 discharges at least a portion of the power of the vehicle battery 40 at timing T34. When the discharge occurs, a discharge current flows through the vehicle battery 40 in the opposite direction to the charging current, causing the measured voltage to drop sharply. Then, the polarization is eliminated quickly, for example, within a few seconds, and the measured voltage stabilizes.

[0067] The control device 70 terminates discharging when the integrated discharge current, which is the amount of discharge current integrated over time, reaches a predetermined target value. The discharge time required for the integrated discharge current to reach the target value can be significantly shorter than in a mode in which the battery is placed in a non-powered state after charging. Furthermore, when the vehicle battery 40 is discharged, the SOC gradually decreases. However, because the discharge time is short, the amount of decrease in SOC can be made much smaller than the increase in SOC due to the main charge.

[0068] At time T35, when the integrated discharge current reaches the target value, the control device 70 terminates the discharge and places the vehicle battery 40 in a non-powered state. The control device 70 then measures the voltage of the vehicle battery 40 in this non-powered state. Because polarization was eliminated during the discharge immediately before the voltage measurement, the control device 70 can obtain a calibrated measured voltage that is substantially free of pseudo-potential differences. The control device 70 derives the SOC based on the calibrated measured voltage. As a result, the calibrated measured voltage and SOC are obtained in the non-powered state between time T35 and time T36. At time T36 after deriving the SOC, the control device 70 resumes primary charging.

[0069] At time T37 after time T36, a predetermined interruption condition is met. For example, the interruption condition is met when the integrated amount of charging current during the period from time T36 to time T37 reaches a predetermined value. When this charging condition is met, the control device 70 temporarily interrupts the main charging.

[0070] The SOC at timing T37 is equal to or greater than the SOC “C30.” Therefore, the control device 70 causes at least a portion of the power of the in-vehicle battery 40 to be discharged at timing T37, similar to timing T34.

[0071] At time T38 when the integrated discharge current reaches the target value, the control device 70 terminates discharging and places the vehicle battery 40 in a non-powered state. Then, the control device 70 measures the voltage of the vehicle battery 40 in this non-powered state. The control device 70 derives the SOC based on the acquired measured voltage. As a result, the calibrated measured voltage and SOC are obtained in the non-powered state between time T38 and time T39. At time T39 after deriving the SOC, the control device 70 resumes main charging.

[0072] At time T40 after time T39, the measured voltage reaches a predetermined upper limit voltage V30, which causes the control device 70 to terminate main charging and put the vehicle battery 40 into a non-energized state.

[0073] Because the measured voltage is calibrated to an appropriate value by discharging during main charging, the error between the SOC based on the measured voltage and the actual SOC can be reduced. Furthermore, the measured voltage is prevented from increasing, which prevents the measured voltage from reaching the measured voltage V30 too early. This prevents the entire charge from being terminated before the actual SOC becomes sufficiently high. For example, as shown by arrow A40 in FIG. 7, the difference between the target SOC "C40" and the actual SOC "C41" at the end of main charging can be reduced.

[0074] At time T41 when the non-energized state has been maintained for a predetermined time, the control device 70 starts forced charging. At time T42 when the measured voltage reaches measured voltage V30 again, the control device 70 ends forced charging. This ends the entire charging process. By performing forced charging, it is possible to further prevent the entire charging process from ending before the actual SOC becomes sufficiently high. For example, as shown by arrow A41 in FIG. 7, it is possible to reduce the difference between the target SOC "C40" and the actual SOC "C42" at the end of forced charging. Note that forced charging may be omitted.

[0075] The following describes the processes of the control device 70 for realizing the above-described charging and discharging operations, and the functional units that perform these processes. Note that the following describes the processes related to charging and discharging in particular, and omits descriptions of other processes.

[0076] 8 is a functional block diagram of the control device 70. The processor 72 of the control device 70 works in cooperation with a program stored in the memory 74 to function as a charging control unit 100. For ease of explanation, the above-mentioned main charging may be simply referred to as charging.

[0077] With the charging connector 24 connected to the charging port 44, the charging control unit 100 charges the vehicle battery 40 with power supplied through the charging port 44. Specifically, the charging control unit 100 turns the second switch 52 off and the first switch 50 on, and supplies the power received from the power supply equipment 10 to the vehicle battery 40.

[0078] The charging control unit 100 interrupts charging of the vehicle battery 40 at a predetermined timing during charging of the vehicle battery 40. Specifically, the charging control unit 100 turns the first switch 50 off. When the charging of the vehicle battery 40 is interrupted, the charging control unit 100 discharges at least a portion of the power of the vehicle battery 40 from the vehicle battery 40. Specifically, the charging control unit 100 turns the second switch 52 on while the first switch 50 is off. A current flows from the vehicle battery 40 to the electrical load 60 through the second switch 52, thereby discharging the vehicle battery 40. Note that the amount of discharged power is assumed to be less than the amount of charged power.

[0079] After discharging the vehicle battery 40, the charging control unit 100 places the vehicle battery 40 in a non-energized state and measures the voltage at the input / output terminals of the vehicle battery 40 using the voltage sensor 80. The charging control unit 100 derives the SOC of the vehicle battery 40 based on the measured voltage of the vehicle battery 40. After measuring the voltage of the vehicle battery 40, more specifically, after deriving the SOC based on the measured voltage, the charging control unit 100 resumes charging the vehicle battery 40.

[0080] Here, the index obtained by integrating the charging current of the vehicle battery 40 over time may be referred to as the integrated charging current. Furthermore, the integrated charging current during the period from the start of charging current flow to its end when charging current is continuously supplied may be referred to as the integrated section charging current. The integrated section charging current indicates, for example, the integrated charging current during the period from the start of charging to the start of a charging interruption. Furthermore, when charging is interrupted multiple times, the integrated section charging current indicates, for example, the integrated charging current during the period from the end of one interruption to the start of the next interruption.

[0081] The charging control unit 100 sets the timing to interrupt charging, i.e., the charging interruption condition, based on the temperature of the in-vehicle battery 40 at the start of charging. The timing to interrupt charging, i.e., the charging interruption condition, is, for example, when the integrated amount of section charging current reaches a predetermined value. The temperature of the in-vehicle battery 40 may also be referred to as the battery temperature.

[0082] For example, the lower the temperature of the in-vehicle battery 40 at the start of charging, the earlier the timing to interrupt charging is set by the charge control unit 100. Because the lower the battery temperature, the greater the effect of polarization, the lower the battery temperature, the earlier the charge control unit 100 interrupts charging and discharges. This allows the measured voltage to be calibrated before the error in the measured voltage becomes excessive, and prevents a decrease in SOC accuracy.

[0083] The charge control unit 100 repeats such interruption of charging and discharging every time the condition for interrupting charging is satisfied. Since the measured voltage is calibrated every time charging is interrupted, it is possible to suppress a decrease in the accuracy of the SOC.

[0084] Here, the index obtained by integrating the discharge current of the in-vehicle battery 40 over time may be referred to as the integrated discharge current amount. The charge control unit 100 executes the discharge so that the actual integrated discharge current amount due to the discharge is equal to or greater than the target value of the integrated discharge current amount.

[0085] The charging control unit 100 derives a target value for the integrated discharge current of the in-vehicle battery 40 based on the integrated section charge current immediately before the start of discharge and the temperature of the in-vehicle battery 40 at the start of discharge. Because the larger the integrated section charge current immediately before the start of discharge, the greater the effect of polarization. Therefore, the charging control unit 100 sets a target value such that the integrated discharge current increases as the integrated section charge current immediately before the start of discharge increases. Furthermore, as described above, because the lower the battery temperature, the greater the effect of polarization. Therefore, the charging control unit 100 sets a target value such that the lower the temperature of the in-vehicle battery 40 at the start of discharge, the greater the integrated discharge current. For example, a discharge current integration setting map that associates the integrated section charge current, battery temperature, and integrated discharge current is stored in advance in the memory 74 of the control device 70. The charge control unit 100 refers to this accumulated discharge current setting map, derives the accumulated discharge current from the accumulated charge current in the section immediately before the start of discharge and the temperature of the in-vehicle battery at the start of discharge, and sets the derived accumulated discharge current to a target value. This allows discharge to be performed with an appropriate accumulated discharge current. Furthermore, by discharging until the actual accumulated discharge current reaches the target value, the discharge time can be optimized.

[0086] During charging, the charging control unit 100 successively derives the SOC of the in-vehicle battery 40 based on the integrated amount of charging current, and calibrates the SOC based on the SOC derived when charging is interrupted.

[0087] When the condition for interrupting charging is met, the charging control unit 100 determines whether the current SOC of the in-vehicle battery 40, i.e., the SOC before calibration immediately before interruption, is equal to or greater than a predetermined value. Here, the influence of polarization is large in a relatively high SOC range, and the influence of polarization is small in a relatively low SOC range. The predetermined value is set taking into consideration the degree of influence of polarization. The predetermined value corresponds to a threshold that distinguishes between a high SOC range where the influence of polarization is large and a low SOC range where the influence of polarization is small. The predetermined value is set to, for example, 50%, but can be set to any value taking into consideration the degree of influence of polarization.

[0088] If the SOC of the in-vehicle battery 40 is equal to or greater than a predetermined value when the condition for interrupting charging is met, the charging control unit 100 executes discharging and, after discharging, measures the voltage of the in-vehicle battery 40. In this way, in a high SOC region where the influence of polarization is large, discharging when charging is interrupted can reliably calibrate the measured voltage and accurately calibrate the SOC.

[0089] On the other hand, if the SOC of the vehicle battery 40 is below a predetermined value when the condition for interrupting charging is met, the charging control unit 100 does not discharge the battery, but puts the battery 40 into a non-powered state and measures the voltage of the battery 40. In the low SOC range where the influence of polarization is small, the SOC error is relatively small, so discharging when charging is interrupted is not necessary. Furthermore, by not discharging the battery, it is possible to suppress the loss of power in the battery 40.

[0090] 9 is a flowchart illustrating the flow of operations of the charging control unit 100. When the charging connector 24 is connected to the charging port 44 and an instruction to start charging is received, the charging control unit 100 executes a series of processes shown in FIG.

[0091] First, the charging control unit 100 acquires the battery temperature at the start of charging from the temperature sensor 84 (S10). Next, the charging control unit 100 sets a condition for interrupting charging based on the battery temperature (S11). For example, because the effect of polarization is greater as the battery temperature decreases, the charging control unit 100 sets a target value for the sectional charging current integrated amount so that the lower the battery temperature, the smaller the target value for the sectional charging current integrated amount. As the target value for the sectional charging current integrated amount decreases, the number of interruptions increases relatively, and the measured voltage is calibrated more frequently. In this way, even if the effect of polarization is significant, an excessive increase in the measured voltage can be appropriately suppressed by calibrating the measured voltage early. For example, when the battery temperature is relatively high, the interruption condition is set to a target value for the sectional charging current integrated amount equivalent to 20% SOC, and when the battery temperature is relatively low, the interruption condition is set to a target value for the sectional charging current integrated amount equivalent to 10% SOC. Note that the SOC values ​​shown are merely examples and can be any value.

[0092] After setting the interruption condition (S11), the charging control unit 100 turns the second switch 52 to the OFF state and turns the first switch 50 to the ON state, and starts charging (S12).

[0093] Next, the charge control unit 100 determines whether a charge termination condition is met (S13). The charge termination condition may be, for example, that the voltage measured by the voltage sensor 80 is equal to or greater than a predetermined voltage, and that forced charging has been completed via step S16, which will be described later. Note that the charge termination condition is not limited to this example and can be set arbitrarily.

[0094] If the charging termination condition is not met (NO in S13), the charging control unit 100 determines whether the forced charging condition is met (S15). The forced charging condition may be, for example, that the forced charging in step S16 described below has not yet been performed and that the voltage measured by the voltage sensor 80 has reached a predetermined voltage. The forced charging condition is not limited to this example and can be set arbitrarily. If the forced charging condition is met (YES in S15), the charging control unit 100 performs forced charging after placing the battery in a non-powered state for a predetermined time (S16). The charging control unit 100 completes forced charging when the voltage measured by the voltage sensor 80 reaches or exceeds the predetermined voltage. The predetermined voltage in the forced charging condition may be set to the same voltage as the predetermined voltage in the charging termination condition. Once forced charging is completed, the charging control unit 100 returns to determining whether the charging termination condition is met (S13). Since the forced charging has been completed via step S16 and the charging end condition is met (YES in S13), the charging control unit 100 ends the charging (S14).

[0095] If the forced charging condition is not met (NO in S15), main charging before forced charging is being performed, and the charging control unit 100 determines whether the interruption condition set in step S11 is met (S17). If the interruption condition is not met (NO in S17), the charging control unit 100 derives the integrated charging current amount based on the current measured by the current sensor 82 (S18). The charging control unit 100 derives the SOC based on the derived integrated charging current amount (S19). The charging control unit 100 returns to step S13 and repeats the processes from step S13 onwards.

[0096] If the interruption condition is met (YES in S17), the charging control unit 100 determines whether the current SOC, i.e., the SOC when the interruption condition is met, is equal to or greater than a predetermined SOC (S20). The predetermined SOC is, for example, 50%, but is not limited to this example.

[0097] If the current SOC is equal to or higher than the predetermined SOC (YES in S20), the charging control unit 100 executes high SOC region processing (S21). The high SOC region processing is processing related to the interruption of charging in a region where the SOC is relatively high. The high SOC region processing will be described in detail later. After executing the high SOC region processing, the charging control unit 100 returns to the processing of step S13 and repeats the processing from step S13 onwards.

[0098] If the current SOC is lower than the predetermined SOC (NO in S20), the charging control unit 100 executes low SOC region processing (S22). The low SOC region processing is processing related to interrupting charging in a region where the SOC is relatively low. The low SOC region processing will be described in detail later. After executing the low SOC region processing, the charging control unit 100 returns to the processing of step S13 and repeats the processing from step S13 onwards.

[0099] 10 is a flowchart illustrating the flow of the high SOC range process (S21). When the high SOC range process (S21) starts, the charge control unit turns off the first switch 50 to suspend charging (S30).

[0100] Next, the charging control unit 100 derives a target value for the accumulated discharge current amount based on the accumulated section charge current amount immediately before the interruption and the battery temperature at the start of the interruption (S31). For example, the charging control unit 100 stores in the memory 74 the accumulated charge current amount at the start of a period during which a charging current is continuously supplied and the accumulated charge current amount at the end of that period. The charging control unit 100 derives the accumulated section charge current amount immediately before the current interruption by subtracting the accumulated charge current amount at the start of the period immediately before the current interruption from the accumulated charge current amount at the end of that period immediately before the current interruption. The charging control unit 100 also acquires the current battery temperature measured by the temperature sensor 84 as the battery temperature at the start of the interruption. The charging control unit 100 applies the derived accumulated section charge current amount and the acquired battery temperature to a discharge current accumulation amount setting map to derive a target value for the accumulated discharge current amount.

[0101] Next, the charge control unit 100 turns on the second switch 52 to start discharging (S32). As a result, at least a portion of the power of the in-vehicle battery 40 is discharged, and the discharged power is consumed by the electric load 60. The charge control unit 100 derives the current integrated amount of discharge current due to the discharge (S33).

[0102] Next, the charge control unit 100 determines whether the current integrated discharge current amount is equal to or greater than the target value for the integrated discharge current amount (S34). If the current integrated discharge current amount is less than the target value for the integrated discharge current amount (NO in S34), the charge control unit 100 repeats the processes from step S32 onwards. That is, discharging continues until the current integrated discharge current amount reaches the target value for the integrated discharge current amount.

[0103] If the current integrated discharge current amount is equal to or greater than the target integrated discharge amount (YES in S34), the charge control unit 100 turns off the second switch 52 while the first switch 50 is in the off state, thereby bringing the in-vehicle battery 40 into a non-energized state (S35), thereby ending the discharge.

[0104] In the power-off state, the charging control unit 100 measures the voltage of the in-vehicle battery 40 using the voltage sensor 80 (S36). By measuring the voltage after discharging, the voltage measured is measured in a state where polarization has been eliminated, and the measured voltage is calibrated. The charging control unit 100 derives the SOC based on the calibrated measured voltage (S37). This also calibrates the SOC. After deriving the SOC, the charging control unit 100 resumes charging (S38).

[0105] 11 is a flowchart illustrating the flow of the low SOC region processing (S22). When the low SOC region processing is started, the charging control unit 100 turns off the first switch 50 and the second switch 52 to put the in-vehicle battery 40 into a non-powered state (S40). The charging control unit 100 determines whether a predetermined time has elapsed since the charging state was changed to a non-powered state (S41). The charging control unit 100 maintains the non-powered state (S40) until the predetermined time has elapsed (NO in S41). By maintaining the non-powered state for the predetermined time, polarization is gradually eliminated.

[0106] If the predetermined time has elapsed (YES in S41), the charging control unit 100 measures the voltage of the in-vehicle battery 40 using the voltage sensor 80 (S42). Because the voltage measurement is performed in a state where polarization is reduced, the error in the measured voltage is reduced. The charging control unit 100 derives the SOC based on the measured voltage (S43). Because the SOC is derived based on the measured voltage with the error reduced, the error in the SOC is also reduced. After deriving the SOC, the charging control unit 100 resumes charging (S44).

[0107] As described above, in the charging device 14 of this embodiment, charging of the vehicle battery 40 is interrupted at a predetermined timing, and at least a portion of the power of the vehicle battery 40 is discharged when the charging device 14 of this embodiment is stopped. As a result, polarization of the vehicle battery 40 is quickly eliminated in the charging device 14 of this embodiment. After the discharge, the charging device 14 of this embodiment measures the voltage of the vehicle battery 40 by putting the vehicle battery 40 into a non-powered state, and derives the SOC based on the measured voltage. As a result, the charging device 14 of this embodiment obtains a measured voltage that is calibrated in a state where polarization is eliminated, and as a result, a calibrated SOC is derived.

[0108] Therefore, according to the charging device 14 of this embodiment, it is possible to reduce errors in the SOC during charging.

[0109] While the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

[0110] For example, in the above embodiment, the power discharged from the vehicle battery 40 is consumed by the electrical load 60 in the vehicle 12. However, during discharging, the voltage on the power supply equipment 10 side may be made lower than the voltage of the vehicle battery 40, and the power discharged from the vehicle battery 40 may be supplied to the power supply equipment 10 side. In this case, the power supplied to the power supply equipment 10 side may be consumed by an electrical device in the power supply equipment 10, or may be supplied to the power grid 26.

[0111] Furthermore, in the above embodiment, the charge control unit 100 places the vehicle battery 40 in an unloaded state after discharging and measures the voltage of the vehicle battery 40 in the unloaded state. However, the charge control unit 100 may resume charging without placing the vehicle battery 40 in an unloaded state after discharging and measure the voltage of the vehicle battery 40 while the vehicle battery 40 is in a powered state. For example, since almost no pseudo-potential difference occurs immediately after resuming charging, the measured voltage in the powered state immediately after resuming charging is calibrated with respect to the voltage measured immediately before discharging. However, the influence of polarization increases as time passes after resuming charging. For this reason, it is more preferable to place the vehicle battery 40 in an unloaded state after discharging and measure the voltage of the vehicle battery 40 in the unloaded state than to resume charging and then measure the voltage of the vehicle battery 40. [Explanation of symbols]

[0112] 12 vehicles 44 Charging port 40 Car Battery 70 Control device 72 processors 74 memory

Claims

1. a charging port electrically connectable to a power source external to the vehicle; an in-vehicle battery electrically connectable to the charging port; a control device that charges the vehicle battery with power supplied through the charging port; Equipped with The control device one or more processors; one or more memories coupled to the processor; and The processor: setting a predetermined timing for interrupting charging of the vehicle-mounted battery based on a temperature of the vehicle-mounted battery at the start of charging; interrupting charging of the vehicle-mounted battery at the set predetermined timing during charging of the vehicle-mounted battery; When charging of the vehicle battery is interrupted, at least a portion of the power of the vehicle battery is discharged from the vehicle battery. measuring the voltage of the vehicle battery after discharging the vehicle battery; Deriving an SOC of the vehicle battery based on the measured voltage of the vehicle battery; A charging device that performs a process including:

2. a charging port electrically connectable to a power source external to the vehicle; an in-vehicle battery electrically connectable to the charging port; a control device that charges the vehicle battery with power supplied through the charging port; Equipped with The control device one or more processors; one or more memories coupled to the processor; and The processor: interrupting charging of the vehicle-mounted battery at a predetermined timing during charging of the vehicle-mounted battery; deriving a target value of an integrated discharge current amount obtained by integrating a discharge current of the vehicle-mounted battery over time based on an integrated charge current amount obtained by integrating a charge current of the vehicle-mounted battery over time and a temperature of the vehicle-mounted battery at the start of discharge; When charging of the vehicle-mounted battery is interrupted, at least a part of the power of the vehicle-mounted battery is discharged from the vehicle-mounted battery so that the actual integrated amount of discharge current due to discharge becomes equal to or greater than the derived target value of the integrated amount of discharge current. measuring the voltage of the vehicle battery after discharging the vehicle battery; Deriving an SOC of the vehicle battery based on the measured voltage of the vehicle battery; A charging device that performs a process including:

3. a charging port electrically connectable to a power source external to the vehicle; an in-vehicle battery electrically connectable to the charging port; a control device that charges the vehicle battery with power supplied through the charging port; Equipped with The control device one or more processors; one or more memories coupled to the processor; and The processor: deriving an SOC of the vehicle-mounted battery based on an integrated charging current amount obtained by integrating a charging current of the vehicle-mounted battery over time while the vehicle-mounted battery is being charged; Suspending charging of the vehicle-mounted battery when a condition for suspending charging is met during charging of the vehicle-mounted battery; If the SOC of the vehicle battery is equal to or higher than a predetermined threshold when a condition for interrupting charging is met, discharging at least a portion of the power of the vehicle battery from the vehicle battery when interrupting charging of the vehicle battery, and measuring the voltage of the vehicle battery after discharging the vehicle battery; If the SOC of the vehicle battery is less than a predetermined threshold when the condition for interrupting charging is met, the vehicle battery is not discharged, but is brought into a non-powered state, and a voltage of the vehicle battery is measured; Deriving an SOC of the vehicle battery based on the measured voltage of the vehicle battery; A charging device that performs a process including:

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