Vehicle and vehicle charging method

Abstract

To improve an accuracy of estimating a full charge capacity of a battery.SOLUTION: An ECU 90 estimates a full charge capacity of a battery 10 based on a first OCV determined from a voltage detected by a voltage sensor 21 before a start of an external charging and a second OCV determined from a voltage detected by the voltage sensor 21 after an end of the external charging. The ECU 90 predicts whether the external charging is completed by a departure time, when assuming that the external charging is started after waiting for a polarization elimination time required for eliminating polarization of the battery 10. When the external charging is predicted to be completed by the departure time, the ECU 90 starts the external charging after waiting for the polarization elimination time, and uses a voltage detected by the voltage sensor 21 after waiting for the polarization elimination time and before starting the external charging as the first OCV, and when the external charging is predicted not to be completed by the departure time, the ECU 90 starts the external charging without waiting for the polarization elimination time.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a vehicle and a charging method for a vehicle, and more particularly to a vehicle configured to be chargeable with electric power supplied from a charging facility and a charging method therefor.

Background Art

[0002] In recent years, the popularity of vehicles such as plug-in hybrid vehicles and electric vehicles has been increasing. These vehicles are configured to be able to charge the battery with electric power supplied from a charging facility. This charging mode is hereinafter also referred to as "external charging".

[0003] As the fully charged capacity of the battery gradually decreases with the use of the vehicle, the driving range of the vehicle (so-called EV range) becomes shorter. Therefore, the fully charged capacity of the battery is an important index for both vehicle manufacturers and users. Thus, a technique for estimating the fully charged capacity of the battery by utilizing an opportunity for external charging has been proposed (see, for example, Japanese Unexamined Patent Application Publication No. 2020-106316 (Patent Document 1)).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The current integration method is widely used to estimate the full charge capacity of a battery. In the current integration method, the OCV (Open Circuit Voltage) determined from the voltage detected by a voltage sensor before the start of battery charging and the OCV determined from the voltage detected by the voltage sensor after the end of battery charging are used. When adopting the current integration method, there is always a requirement to estimate the full charge capacity of the battery with as high an accuracy as possible.

[0006] The present disclosure has been made to solve the above problems, and an object of the present disclosure is to improve the estimation accuracy of the full charge capacity of a battery.

Means for Solving the Problems

[0007] (1) A vehicle according to an aspect of the present disclosure is configured to be capable of external charging by electric power supplied from a charging facility. The vehicle includes a battery, a voltage sensor that detects the voltage of the battery, a first OCV (Open Circuit Voltage) determined from the voltage detected by the voltage sensor before the start of external charging, and a control device that estimates the full charge capacity of the battery based on a second OCV determined from the voltage detected by the voltage sensor after the end of external charging. The control device predicts whether external charging will be completed by the departure time of the vehicle, assuming that external charging starts after waiting for a first polarization elimination time required to eliminate the polarization of the battery that occurred before the start of external charging. When it is predicted that external charging will be completed by the departure time, the control device waits for the first polarization elimination time and then starts external charging, and uses the voltage detected by the voltage sensor after waiting for the first polarization elimination time and before the start of external charging as the first OCV. On the other hand, when it is predicted that external charging will not be completed by the departure time, the control device starts external charging without waiting for the first polarization elimination time.

[0008] (2) Assuming that the control device waits for the first depolarization elimination time and then starts external charging, and waits for the second depolarization elimination time required to eliminate the polarization of the battery caused by the external charging after the external charging ends, the control device predicts whether the external charging will be completed by the departure time. When it is predicted that the external charging will be completed by the departure time, the control device uses the voltage detected by the voltage sensor after waiting for the second depolarization elimination time as the second OCV.

[0009] (3) When the estimated time obtained by subtracting the first and second depolarization elimination times from the time until the departure time is shorter than the charging required time of the battery, the control device predicts that the external charging will be completed by the departure time. When the estimated time is longer than the charging required time, the control device predicts that the external charging will not be completed by the departure time.

[0010] (4) When the estimated time at which the first depolarization elimination time, the charging required time of the battery, and the second depolarization elimination time have elapsed is earlier than the departure time, the control device predicts that the external charging will be completed by the departure time. When the estimated time is later than the departure time, the control device predicts that the external charging will not be completed by the departure time.

[0011] In the configuration of (1) above, the polarization generated before the start of the external charging is eliminated by waiting for the first depolarization elimination time before the start of the external charging. Thereby, the first OCV before the start of the external charging can be obtained with high accuracy. In the configuration of (2) above, furthermore, the polarization generated by the external charging is eliminated by waiting for the second depolarization elimination time after the end of the external charging. Thereby, the second OCV after the end of the external charging can be obtained with high accuracy. However, waiting as described above is the case where it is predicted that the external charging of the battery will be completed even if waiting. When it is predicted that the external charging of the battery will not be completed by waiting, the external charging is started without waiting, so that the shortening of the EV distance of the vehicle is suppressed. Therefore, according to the configurations of (1) to (4) above, the estimation accuracy of the full charge capacity of the battery can be improved without impairing the convenience of the user.

[0012] (5) The control device estimates the departure time based on the learning results regarding the past departure times of the vehicle.

[0013] (6) The control device acquires the departure time determined by the operation of the user of the vehicle.

[0014] In the configurations of (5) and (6) above, a departure time with high accuracy can be acquired. As a result, it becomes possible to accurately predict whether external charging will be completed by the departure time.

[0015] (7) In the charging method for a vehicle according to another aspect of the present disclosure, the vehicle is configured to be capable of external charging of the battery with the electric power supplied from the charging facility. Further, the vehicle is configured to estimate the full charge capacity of the battery based on a first OCV determined from the voltage detected by the voltage sensor before the start of external charging and a second OCV determined from the voltage detected by the voltage sensor after the end of external charging. The charging method includes first to third steps. The first step is a step of predicting whether external charging will be completed by the departure time of the vehicle assuming that external charging starts after waiting for a depolarization elimination time required to eliminate the polarization of the battery that occurred before the start of external charging. The second step is a step of starting external charging after waiting for the depolarization elimination time when it is predicted that external charging will be completed by the departure time, and using the voltage detected by the voltage sensor after waiting for the depolarization elimination time and before the start of external charging as the first OCV. The third step is a step of starting external charging without waiting for the depolarization elimination time when it is predicted that external charging will not be completed by the departure time.

[0016] According to the method of (7) above, similar to the configuration of (1) above, the estimation accuracy of the full charge capacity of the battery can be improved.

Advantages of the Invention

[0017] According to the present disclosure, in a vehicle configured to be capable of external charging, the estimation accuracy of the full charge capacity of the battery can be improved.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

[0020] [Embodiment] [System Configuration] FIG. 1 is a diagram schematically showing the overall configuration of a vehicle according to an embodiment of the present disclosure. The vehicle 1 is configured to enable "plug-in charging" with electric power supplied from a charging facility (not shown). The vehicle 1 is, for example, an electric vehicle (EV: Electric Vehicle), but its type is not particularly limited. The vehicle 1 may be a plug-in hybrid vehicle (PHV: Plug-in Hybrid Vehicle).

[0021] Vehicle 1 includes a battery 10, a monitoring unit 20, a system main relay (SMR) 30, an inlet 40, an AC / DC converter 50, a charge relay (CHR) 60, a power control unit (PCU) 71, a motor generator (MG) 72, a power transmission gear 73, drive wheels 74, a data communication module (DCM) 80, and an electronic control unit (ECU) 90.

[0022] The battery 10 is a battery pack including a plurality of cells. Each cell is a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The battery 10 stores electric power for driving the motor generator 72 and supplies the electric power to the motor generator 72 through the PCU 71. Further, the battery 10 is charged by receiving the generated electric power through the PCU 71 when the motor generator 72 generates power.

[0023] The monitoring unit 20 includes various sensors for monitoring the state of the battery 10. Specifically, the monitoring unit 20 includes a voltage sensor 21, a current sensor 22, and a temperature sensor 23. The voltage sensor 21 detects the voltage VB of the battery 10. The current sensor 22 detects the current IB input to and output from the battery 10. The temperature sensor 23 detects the temperature TB of the battery 10. Each sensor outputs its detected value to the ECU 90.

[0024] The SMR 30 is provided on the power line connecting the battery 10, the PCU 71, and the AC / DC converter 50. The SMR 30 is opened and closed according to a command from the ECU 90. When the SMR 30 is opened (turned off), the battery 10 is electrically disconnected from the PCU 71 and the AC / DC converter 50.

[0025] The inlet 40 is configured such that a connector (not shown) provided at the tip of the charging cable is connected with mechanical connection. When the inlet 40 and the connector are connected, an electrical connection between the charging facility and the vehicle 1 is ensured. Also, the ECU 90 of the vehicle 1 and a control device (not shown) of the charging facility can mutually transmit and receive various commands and data according to a predetermined communication standard.

[0026] The AC / DC converter 50 converts the AC power supplied from the charging facility via the charging cable into DC power for charging the battery 10. When the vehicle 1 supports rapid charging, the vehicle 1 may include a DC / DC converter 50 instead of or in addition to the AC / DC converter 50.

[0027] The CHR 60 is connected in series with the SMR 30 to the power line connecting the battery 10 and the AC / DC converter 50. The CHR 60 is opened and closed, for example, according to a command from the ECU 90. When the CHR 60 is closed (on) and the SMR 30 is closed, the battery 10 can be charged by the power from the inlet 40.

[0028] The PCU 71 is electrically connected between the SMR 30 and the motor generator 72. The PCU 71 includes a converter and an inverter (both not shown) and drives the motor generator 72 according to a command from the ECU 90.

[0029] The motor generator 72 is an AC rotating electric machine, for example, a permanent magnet type synchronous motor having a rotor in which permanent magnets are embedded. The output torque of the motor generator 72 is transmitted to the drive wheels 74 through the power transmission gear 73 to drive the vehicle 1. Also, the motor generator 72 can generate electricity by the rotational force of the drive wheels 74 during the braking operation of the vehicle 1. The generated power by the motor generator 72 is converted into charging power for the battery 10 by the PCU 71.

[0030] The DCM80 is configured to enable two-way communication with a user terminal U (e.g., a smartphone) outside the vehicle 1. Thereby, the vehicle 1 can receive user operations related to plug-in charging (such as the operation of setting the departure time described later).

[0031] The ECU 90 includes a processor 91 such as a CPU (Central Processing Unit), a memory 92 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input / output port (not shown) through which various signals are input and output. The ECU 90 executes various controls for controlling the vehicle 1 to a desired state based on the signals received from each sensor and the programs and maps stored in the memory 92. For example, the ECU 90 controls the plug-in charging of the vehicle 1 by communicating with the charging facility and controlling the SMR 30, the AC / DC converter 50, and the CHR 60. Further, the ECU 90 manages the state of the battery 10 using the monitoring unit 20. As a main process executed by the ECU 90 in the present embodiment, there is a process of estimating the full charge capacity of the battery 10 by using the opportunity of plug-in charging of the vehicle 1. This process is referred to as a "capacity estimation process" and will be described in detail.

[0032] Note that the ECU 90 may be configured to be divided into a plurality of ECUs for each function. For example, the ECU 90 may be divided into an ECU that manages the state of the battery 10, an ECU that controls the AC / DC converter 50, and an ECU that controls the PCU 71. The ECU 90 corresponds to the "control device" according to the present disclosure.

[0033] <Capacity Estimation Process> In the capacity estimation process, the ECU 90 estimates the full charge capacity of the battery 10 by using the voltage of the battery 10 before the start of plug-in charging, the voltage of the battery 10 after the end of plug-in charging, and the integrated value of the current charged to the battery 10 during plug-in charging (current integration method). Here, it is necessary that both the voltage before the start of plug-in charging and the voltage after the end of plug-in charging are open circuit voltages (OCV: Open Circuit Voltage).

[0034] However, immediately after the user returns home, which is one of the main assumed scenarios of plug-in charging, the user who has driven the vehicle 1 back home connects the charging cable to the inlet 40 before getting out of the vehicle 1 and entering indoors. Then, charging of the battery 10 starts immediately thereafter. In such a charging scenario, since discharge due to the running of the vehicle 1 has just ended, polarization has occurred in the battery 10. Therefore, the voltage VB detected by the voltage sensor 21 deviates from the OCV by the amount of the influence of polarization. Then, the estimation accuracy of the full charge capacity of the battery 10 may decrease.

[0035] Therefore, in the present embodiment, a configuration is adopted in which the estimation accuracy of the full charge capacity is improved by using the voltage VB detected after waiting until the polarization is eliminated. However, if waiting uniformly until the polarization is eliminated, the completion time of plug-in charging will be delayed accordingly, and there is a possibility that the plug-in charging will not be completed by the user's next departure time. As a result, the EV distance of the vehicle 1 becomes short, and the convenience of the user may be impaired. Therefore, in the present embodiment, whether to wait until the polarization is eliminated is determined in consideration of whether there is a time margin until the user's departure time arrives. More specifically, if it is predicted that the plug-in charging will be completed by the user's departure time even if waiting until the polarization is eliminated, it is determined to wait until the polarization is eliminated. On the other hand, if there is a possibility that the plug-in charging will not be completed by the user's departure time if waiting until the polarization is eliminated, it is determined to start the plug-in charging without waiting until the polarization is eliminated.

[0036] FIG. 2 is a time chart for explaining the capacity estimation process when there is a time margin until the departure time. In FIG. 2 and FIG. 3 described later, the horizontal axis represents the elapsed time. The vertical axis represents the voltage of the battery 10 (more specifically, the total voltage of the OCV and the polarization voltage).

[0037] The vehicle 1 that is initially traveling arrives at the installation location of the charging facility (for example, the user's home) at time ta. When the user gets out of the vehicle 1, the user connects the charging cable to the inlet 40. The ECU 90 calculates the charging required time Tch (the time required to fully charge the battery 10 in this example) and acquires the user's next departure time tb. Details of the method for acquiring the departure time tb will be described later.

[0038] Furthermore, the ECU 90 calculates the standby time before the start of plug-in charging. This standby time is the time required until the polarization generated in the battery 10 discharged as the vehicle 1 travels is eliminated (sufficiently relaxed). This time is hereinafter referred to as the "first polarization elimination time T1".

[0039] In addition, the ECU 90 calculates the standby time after the end of plug-in charging. This standby time is the time required until the polarization generated in the battery 10 by plug-in charging is eliminated (sufficiently relaxed). This time is hereinafter referred to as the "second polarization elimination time T2".

[0040] The ECU 90 determines whether the plug-in charging of the vehicle 1 is completed by the departure time tb assuming that it waits for the first polarization elimination time T1 before the start of plug-in charging and also waits for the second polarization elimination time T2 after the end of plug-in charging. For example, the ECU 90 calculates the time obtained by subtracting the first polarization elimination time T1 and the second polarization elimination time T2 from the period from the current time ta to the departure time tb. This time is referred to as the "assignable time ΔT for charging the battery 10" (corresponding to the "estimated time" according to the present disclosure).

[0041] Then, the ECU 90 compares the allocable time ΔT with the charging required time Tch. In the example shown in FIG. 2, the allocable time ΔT is longer than the charging required time Tch. In this case, the ECU 90 can determine that the plug-in charging of the vehicle 1 will be completed by the departure time tb even if it waits before and after the start of the plug-in charging. Therefore, the ECU 90 decides to wait until the polarization is eliminated both before and after the start of the plug-in charging as assumed above.

[0042] FIG. 3 is a time chart for explaining the capacity estimation process when there is no time margin until the departure time. In FIG. 3, the assumed control is shown above, and the actually executed control is shown below.

[0043] In the example shown in FIG. 3, compared with the example shown in FIG. 2, the SOC of the battery 10 when the vehicle 1 arrives at the user's home (refer to the time ta) is low, so the charging required time Tch is long. Therefore, when comparing the allocable time ΔT with the charging required time Tch, the allocable time ΔT is shorter than the charging required time Tch. In this case, if it waits before and after the start of the plug-in charging, the departure time tb will arrive before the plug-in charging of the vehicle 1 is completed. Therefore, the ECU 90 starts the plug-in charging of the vehicle 1 without waiting until the polarization is eliminated before the start of the plug-in charging.

[0044] Thus, prior to the start of the plug-in charging, when it is predicted that the plug-in charging will be completed by the arrival of the user's departure time tb even if waiting until the polarization is eliminated, the ECU 90 decides to wait for the polarization to be eliminated. Thereby, the full charge capacity of the battery 10 can be estimated with high accuracy. On the other hand, when it is predicted that the plug-in charging will not be completed by the arrival of the departure time tb if waiting until the polarization is eliminated, the ECU 90 decides to start the plug-in charging without waiting until the polarization is eliminated. In other words, the ECU 90 prioritizes ensuring the convenience of the user over accurately estimating the full charge capacity.

[0045] <Processing Flow> Figure 4 is a flowchart showing the processing procedure of the capacity estimation process in the present embodiment. This flowchart is executed, for example, when the connector of the charging cable extending from the charging facility is connected to the inlet 40. Each step included in the flowchart shown in FIG. 2 and other flowcharts described later is basically realized by software processing by the ECU 90, but may also be realized by hardware (electrical circuit) arranged in the ECU 90. Hereinafter, steps are abbreviated as S.

[0046] At the start of execution of the flowchart shown in FIG. 2, CHR60 is open. Therefore, the battery 10 is electrically disconnected from the AC / DC converter 50.

[0047] In S1, the ECU 90 determines whether the condition for updating the full charge capacity C of the battery 10 is satisfied. For example, when a predetermined period has elapsed since the previous estimation of the full charge capacity C of the battery 10, it is determined that the update condition is satisfied. When the update condition is satisfied (YES in S1), the ECU 90 acquires the current time ta (S2).

[0048] In S3, the ECU 90 calculates the charging time Tch of the battery 10. More specifically, the ECU 90 can calculate the charging time Tch by dividing the amount of electric power charged to the battery 10 by the charging power per unit time to the battery 10. The amount of electric power charged to the battery 10 is calculated by multiplying the full charge capacity C of the battery 10 (for example, the previous estimated value) by the difference (ΔSOC) between the target SOC and the current SOC. Regarding the charging power per unit time, the power supply capacity of the charging facility can be acquired by communication between the vehicle 1 and the charging facility. Note that the current amount (unit: Ah) may be used instead of the electric power amount (unit: Wh).

[0049] In S4, the ECU 90 calculates a first polarization elimination time T1 required to eliminate the polarization generated in the battery 10 due to the discharge before the plug-in charging. The polarization voltage generated in the battery 10 depends on the charge / discharge current IB of the battery 10 and the temperature TB of the battery 10. Therefore, for example, a map in which the relationship between the current IB discharged from the battery 10 within a recent predetermined time, the temperature TB of the battery 10, and the first polarization elimination time T1 is experimentally obtained is created and stored in the memory 92 of the ECU 90. By referring to this map, the ECU 90 can calculate the first polarization elimination time T1 from the discharge current IB (measured value) and the temperature TB (measured value) within a recent predetermined time. However, the calculation method of the first polarization elimination time T1 is not limited to this. For example, the time required to eliminate the maximum polarization that can occur under normal use conditions of the vehicle 1 may be obtained through a preliminary experiment, and that time (i.e., a fixed value) may be used as the first polarization elimination time T1.

[0050] In S5, the ECU 90 calculates a second polarization elimination time T2 required to eliminate the polarization generated in the battery 10 due to the plug-in charging. The second polarization elimination time T2 can also be calculated using a map in the same manner as the first polarization elimination time T1. In this map, the relationship between the current IB charged to the battery 10 within a recent predetermined time, the temperature TB of the battery 10, and the second polarization elimination time T2 is defined. By referring to this map, the ECU 90 can calculate the second polarization elimination time T2 from the charging current IB (planned value of the plug-in charging) and the temperature TB (predicted value at the time of completion of charging) within a recent predetermined time. Note that the second polarization elimination time T2 may also be a fixed value obtained experimentally in advance.

[0051] In S6, the ECU 90 acquires the departure time tb of the user. For example, the ECU 90 can acquire the departure time tb set by the user operating the user terminal U via the DCM 80. Alternatively, the ECU 90 may use the average departure time as the departure time tb based on the learning result regarding the usage history (user behavior history) of the vehicle 1. This learning method will be described later (see FIGS. 8 and 9).

[0052] In S7, the ECU 90 calculates an allocable time ΔT by subtracting a first depolarization elimination time T1 and a second depolarization elimination time T2 from the period from the current time ta to the departure time tb (see the following formula (1)). ΔT = (tb - ta) - T1 - T2 ···(1)

[0053] In S8, the ECU 90 predicts whether the plug-in charging will be completed by the user's departure time tb. More specifically, the ECU 90 compares the charging required time Tch calculated in S3 with the allocable time ΔT calculated in S7. When the allocable time ΔT is greater than or equal to the charging required time Tch (YES in S8), the ECU 90 predicts that the plug-in charging will be completed by the user's departure time, and executes a "standby estimation process" of waiting for depolarization elimination (S9). On the other hand, when the allocable time ΔT is shorter than the charging required time Tch (NO in S8), the ECU 90 predicts that the plug-in charging will not be completed by the user's departure time, and executes a "non-standby estimation process" that does not wait for depolarization elimination (S10). Thereby, a series of processes are completed.

[0054] In FIG. 4, an example of predicting whether the plug-in charging will be completed by the user's departure time tb by comparing the charging required time Tch and the allocable time ΔT has been described. However, the method of predicting whether the plug-in charging can be completed is not limited to this. For example, the ECU 90 can calculate the time (the completion time of the plug-in charging including the standby before and after the plug-in charging) when the first depolarization elimination time T1, the charging required time Tch, and the second depolarization elimination time T2 have elapsed starting from the current time ta, and compare that time with the departure time tb. The ECU 90 can predict that the plug-in charging will be completed by the user's departure time tb when the time is earlier than the departure time tb, while predicting that the plug-in charging will not be completed by the user's departure time tb when the time is later than the departure time tb.

[0055] FIG. 5 is a flowchart showing the processing procedure of the standby estimation process. In S101, the ECU 90 determines whether the first polarization elimination time T1 has elapsed from the current time ta. The ECU 90 waits until the first polarization elimination time T1 elapses (NO in S101). When the first polarization elimination time T1 elapses (YES in S101), the ECU 90 acquires the voltage VB of the battery 10 from the voltage sensor 21 (S102). At this point, the polarization has been eliminated, and the charge and discharge of the battery 10 have not been performed (IR drop amount = 0), so the voltage VB can be approximated to be equal to the OCV of the battery 10. Therefore, the voltage VB at this time is described as "OCV1" (corresponding to the first OCV).

[0056] In S103, after closing (turning on) the CHR60, the ECU 90 controls the AC / DC converter 50 so that charging of the battery 10 is started. Also, when charging of the battery 10 is started, the ECU 90 starts sequential integration (current integration) of the detection value of the current sensor 22.

[0057] In S104, the ECU 90 determines whether the end condition of the plug-in charging is satisfied. For example, the end condition of the plug-in charging is satisfied when the SOC of the battery 10 reaches the target SOC or a predetermined amount of electric power is charged to the battery 10. When the end condition of the plug-in charging is satisfied (YES in S104), the ECU 90 controls the AC / DC converter 50 so that charging of the battery 10 is terminated and also terminates the current integration (S105). Also, the ECU 90 opens (turns off) the CHR60.

[0058] In S106, the ECU 90 determines whether the second polarization elimination time T2 has elapsed from the end time of charging of the battery 10. The ECU 90 waits until the second polarization elimination time T2 elapses (NO in S106). When the second polarization elimination time T2 elapses (YES in S106), the ECU 90 acquires the voltage VB of the battery 10 from the voltage sensor 21 (S107). Since the voltage VB at this time can also be approximated to be equal to the OCV, it is described as "OCV2" (corresponding to the second OCV).

[0059] In S108, the ECU 90 calculates the change amount ΔSOC of the SOC of the battery 10 during current integration based on the OCV1 of the battery 10 at the start of current integration and the OCV2 of the battery 10 at the end of current integration. Specifically, in the memory 92 of the ECU 90, a curve (SOC-OCV curve) showing the correspondence between the SOC and the OCV of the battery 10 is stored. The ECU 90 can calculate the difference between the SOC (denoted as SOC2) corresponding to OCV2 and the SOC (denoted as SOC1) corresponding to OCV1 on the SOC-OCV curve as ΔSOC (see the following formula (2)). ΔSOC = SOC2 - SOC1 ···(2)

[0060] In S109, the ECU 90 calculates the current integration amount ΔAh (unit: Ah) from the start of current integration to the end of current integration.

[0061] In S110, the ECU 90 estimates the full charge capacity C of the battery 10 based on the ΔSOC calculated in S108 and the current integration value ΔAh calculated in S109. Specifically, the full charge capacity C of the battery 10 can be calculated according to the following formula (3) assuming that the ratio of the charge current value ΔAh to ΔSOC and the ratio of the full charge capacity C to ΔSOC = 100% are equal. Since the full charge capacity C0 in the initial state is known from the specifications of the battery 10, the ECU 90 may further calculate the capacity retention rate Q from the full charge capacity C (Q = C / C0). C = ΔAh / ΔSOC × 100 ···(3)

[0062] FIG. 6 is a flowchart showing another example of the processing procedure of the standby estimation process. This flowchart is different from the flowchart of the standby estimation process described in FIG. 5 in that it includes a process of waiting for the first polarization dissipation time T1 (S201) while not including a process of waiting for the second polarization dissipation time T2 (see S106 in FIG. 5). Thus, it is not essential to set both the first polarization dissipation time T1 and the second polarization dissipation time T2, and only the first polarization dissipation time T1 for waiting for the polarization generated by the discharge of the battery 10 to be dissipated before the start of the plug-in charging may be set. In this case, the process of S5 (see FIG. 4) for calculating the second polarization dissipation time T2 in the capacity estimation process is omitted. Also, the available time ΔT is calculated by ΔT = (tb - ta) - T1.

[0063] The processes of S201 to S204 until the end condition of the current integration is satisfied in FIG. 6 are the same as the processes of S101 to S104 described in FIG. 5. When the end condition of the current integration is satisfied (YES in S204), the ECU 90 acquires the voltage VB of the battery 10 from the voltage sensor 21 (S205). This voltage VB is denoted as "VB2".

[0064] In S206, the ECU 90 calculates the polarization voltage Vp2 generated in the battery 10 after the charging is completed. The polarization voltage Vp2 can be calculated, for example, by using a map in which the relationship between the current IB charged in the battery 10 within a predetermined time immediately before the end of the current integration, the temperature TB of the battery 10, and the polarization voltage Vp2 has been experimentally obtained.

[0065] In S207, the ECU 90 calculates the OCV (denoted as "OCV2") of the battery 10 after the current integration is completed. OCV2 is calculated by subtracting the polarization voltage Vp2 calculated in S207 from the voltage VB2 acquired in S206 and the IR drop amount (= IB × R) (see the following formula (4)). Note that as the internal resistance R, a known fixed value may be used, or a value considering the temperature dependence (a variable value according to the temperature TB) may be used. OCV2 = VB2 - Vp2 - IB × R ···(4)

[0066] Then, the ECU 90 controls the AC / DC converter 50 so that the charging of the battery 10 is completed, and ends the current integration (S208). Since the processes of S209 to S211 hereafter are the same as the processes of S108 to S110 in FIG. 5 (see FIG. 5), the description will not be repeated.

[0067] FIG. 7 is a flowchart showing the processing procedure of the non-standby estimation process. In S301, the ECU 90 acquires the voltage VB of the battery 10 from the voltage sensor 21 before the start of current integration. This voltage VB is denoted as "VB1".

[0068] In S302, the ECU 90 calculates the polarization voltage Vp1 generated in the battery 10 after the end of discharge accompanying the running of the vehicle 1. The polarization voltage Vp1 can be calculated by using a map in which the relationship between the current IB discharged from the battery 10, the temperature TB of the battery 10, and the polarization voltage Vp1 within a recent predetermined time has been experimentally obtained.

[0069] In S303, the ECU 90 calculates the OCV of the battery 10 before the start of current integration. This OCV is denoted as "OCV1". OCV1 is calculated by adding the polarization voltage Vp1 calculated in S302 to the voltage VB1 acquired in S301 (see the following formula (5)). OCV1 = VB1 + Vp1 ···(5)

[0070] Since the processes of S304 to S312 hereafter are the same as the corresponding processes among S103 to S110 and S203 to S211 in the standby estimation process (see FIG. 5 or FIG. 6), detailed description will not be repeated.

[0071] Note that in FIG. 7, an example of estimating the full charge capacity C has been described even when there is no time margin for waiting until depolarization is completed (when it is predicted that the plug-in charging will not be completed by the departure time tb). However, estimating the full charge capacity C may be limited to the case where there is a time margin for waiting for depolarization, and when there is no time margin, the estimation of the full charge capacity C may not be performed.

[0072] <Learning of departure time> As described above, the ECU 90 can learn the departure time tb of the vehicle 1 based on the user's behavior history. As an example, the ECU 90 can learn the average departure time of the vehicle 1 and use the learned value as the departure time tb.

[0073] FIG. 8 is a flowchart showing an example of a processing procedure related to the learning of the departure time. In S401, the ECU 90 records the departure time of the vehicle 1. For example, the ignition-on (IG-ON) time of the vehicle 1 can be used as the departure time.

[0074] In S402, the ECU 90 determines whether the number of records of the departure time exceeds a predetermined number. If the number of records of the departure time exceeds the predetermined number (YES in S402), the ECU 90 determines whether the departure time recorded in S401 is included in the learning section (S403).

[0075] FIG. 9 is a diagram showing an example of the variation in the departure time. In FIG. 9, the horizontal axis represents the number of records of the departure time, and the vertical axis represents the departure time. Referring to FIGS. 8 and 9, in this example, the learning section is set based on the past departure times of the vehicle 1. For example, a section having a predetermined time width (for example, 40 minutes) before and after the average departure time of the vehicle 1 can be set as the learning section. Also, the learning section may be set in consideration of the section where the departure time varies before and after the average departure time. For example, a section of the average departure time ± 2σ (σ: standard deviation of the departure time) can be set as the learning section.

[0076] If the departure time is within the learning section (YES in S403), the ECU 90 learns the departure time recorded in S401 (S404). That is, the ECU 90 updates the average departure time and the learning section using the departure time recorded in S401. On the other hand, if the departure time is outside the learning range (NO in S403), the ECU 90 discards the departure time recorded in S401 without learning it (S405).

[0077] In addition, when the number of times the departure time is recorded does not exceed a predetermined number (NO in S402), the ECU 90 skips the process of S403. That is, the ECU 90 learns without discarding the recorded departure time.

[0078] As described above, in the present embodiment, the polarization generated in the battery 10 as the vehicle 1 travels is eliminated by waiting for the first polarization elimination time T1 before the start of plug-in charging. Thereby, the voltage (OCV1) before the start of charging can be acquired with high accuracy. Also, the polarization generated in the battery 10 due to the plug-in charging of the vehicle 1 is eliminated by waiting for the second polarization elimination time T2 after the end of the plug-in charging. Thereby, the voltage (OCV2) after the end of charging can be acquired with high accuracy. Therefore, the estimation accuracy of the full charge capacity C calculated using OCV1 and OCV2 can be improved.

[0079] However, waiting before (and after) the start of charging is the case where it is predicted that the plug-in charging will be completed even if waiting for only the first polarization elimination time T1 (and the second polarization elimination time T2). When it is predicted that the plug-in charging will not be completed by waiting for only the first polarization elimination time T1 (and the second polarization elimination time T2), ensuring the power of the battery 10 is prioritized over improving the estimation accuracy of the full charge capacity C. Thereby, it is possible to suppress a decrease in user convenience due to a shortening of the EV distance of the vehicle 1. Therefore, according to the present embodiment, it is possible to improve the estimation accuracy of the full charge capacity C of the battery 10 without impairing the user convenience.

[0080] In the present embodiment, the configuration in which the vehicle 1 is plug-in charged has been described as an example. However, the mode of external charging of the vehicle 1 is not limited to plug-in charging. The vehicle 1 may be configured to enable "contactless charging" in which power is transmitted non-contact from a power transmission device buried in the ground to an in-vehicle power reception device.

[0081] The embodiments disclosed herein should be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of the claims rather than the description of the above embodiments, and it is intended that all modifications within the meaning and scope equivalent to the scope of the claims be included.

Explanation of Reference Numerals

[0082] 1 Vehicle, 10 Battery, 20 Monitoring Unit, 21 Voltage Sensor, 22 Current Sensor, 23 Temperature Sensor, 30 SMR, 40 Inlet, 50 AC / DC Converter, 60 CHR, 71 PCU, 72 Motor Generator, 73 Power Transmission Gear, 74 Drive Wheel, 80 DCM, 90 ECU, 91 Processor, 92 Memory, U User Terminal.

Claims

1. A vehicle configured to be externally chargeable by electric power supplied from a charging device, a battery, a voltage sensor for detecting the voltage of the battery, and a control device for estimating the full charge capacity of the battery based on a first OCV determined from the voltage detected by the voltage sensor before the start of the external charge and a second OCV determined from the voltage detected by the voltage sensor after the end of the external charge. The control device, calculates the first polarization relaxation time from the current and the temperature by referring to a map in which the relationship between the current discharged from the battery within a first time prior to the external charge, the temperature of the battery, and the first polarization relaxation time required to eliminate the polarization of the battery generated before the start of the external charge is obtained, calculates the second polarization relaxation time from the current and the temperature by referring to a map in which the relationship between the current charged to the battery within a second time prior to the external charge, the temperature of the battery, and the second polarization relaxation time required to eliminate the polarization of the battery generated by the external charge is obtained, predicts whether the external charge will be completed by the departure time of the vehicle assuming that the external charge is started after waiting for the first polarization relaxation time and that the external charge is waited for the second polarization relaxation time after the end of the external charge, when it is predicted that the external charge will be completed by the departure time, the external charge is started after waiting for the first polarization relaxation time, and the voltage detected by the voltage sensor after waiting for the first polarization relaxation time and before the start of the external charge is used as the first OCV, and the voltage detected by the voltage sensor after waiting for the second polarization relaxation time is used as the second OCV to estimate the full charge capacity of the battery, while when it is predicted that the external charge will not be completed by the departure time, the vehicle starts the external charge without waiting for the first polarization relaxation time.

2. The control device predicts that the external charging will be completed by the departure time when the estimated time obtained by subtracting the first and second depolarization elimination times from the time until the departure time is longer than the charging required time of the battery, and predicts that the external charging will not be completed by the departure time when the estimated time is shorter than the charging required time. The vehicle according to claim 1.

3. The control device predicts that the external charging will be completed by the departure time when the estimated time at which the first depolarization elimination time, the charging required time of the battery, and the second depolarization elimination time have elapsed is earlier than the departure time, and predicts that the external charging will not be completed by the departure time when the estimated time is later than the departure time. The vehicle according to claim 1.

4. The control device estimates the departure time based on a learning result regarding a past departure time of the vehicle. The vehicle according to any one of claims 1 to 3.

5. The control device acquires the departure time determined by an operation of a user of the vehicle. The vehicle according to any one of claims 1 to 3.

6. A charging method for a vehicle configured to enable external charging of a battery with electric power supplied from a charging facility, wherein the vehicle is configured to estimate a full charge capacity of the battery based on a first OCV determined from a voltage detected by a voltage sensor before the start of the external charging and a second OCV determined from a voltage detected by the voltage sensor after the end of the external charging, and the charging method Wait for the first depolarization elimination time required to eliminate the polarization of the battery that occurred before the start of the external charging, and then start the external charging. Assume that when waiting for the second depolarization elimination time required to eliminate the polarization of the battery caused by the external charging after the end of the external charging, predict whether the external charging will be completed by the departure time of the vehicle. When it is predicted that the external charging will be completed by the departure time, wait for the depolarization elimination time and then start the external charging. Use the voltage detected by the voltage sensor after waiting for the first depolarization elimination time and before the start of the external charging as the first OCV, and use the voltage detected by the voltage sensor after waiting for the second depolarization elimination time as the second OCV to estimate the full charge capacity of the battery. When it is predicted that the external charging will not be completed by the departure time, start the external charging without waiting for the first depolarization elimination time. The predicting step includes: By referring to a map in which the relationship between the current discharged from the battery within the first time before the external charging, the temperature of the battery, and the first depolarization elimination time is obtained, calculate the first depolarization elimination time from the current and the temperature. By referring to a map in which the relationship between the current charged into the battery within the second time before the external charging, the temperature of the battery, and the second depolarization elimination time is obtained, calculate the second depolarization elimination time from the current and the temperature. A charging method for a vehicle.

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