JP7694065B2 - Vehicle and method for charging the vehicle - Google Patents

Description

This disclosure relates to a vehicle and a method for charging the vehicle, and more specifically to a vehicle configured to be charged using power supplied from a charging facility, and a method for charging the vehicle.

In recent years, vehicles such as plug-in hybrid vehicles and electric vehicles have become increasingly popular. These vehicles are configured so that their batteries can be charged using power supplied from a charging facility. Hereinafter, this form of charging will also be referred to as "external charging."

When the battery's full charge capacity gradually decreases with vehicle use, the vehicle's drivable distance (so-called EV distance) becomes shorter. Therefore, the battery's full charge capacity is an important indicator for both vehicle manufacturers and users. Therefore, technology has been proposed that estimates the battery's full charge capacity by taking advantage of external charging opportunities (see, for example, JP 2020-106316 A (Patent Document 1)).

JP 2020-106316 A JP 2014-241656 A

The current integration method is widely used to estimate the full charge capacity of a battery. In the current integration method, an OCV (Open Circuit Voltage) is used, which is determined from the voltage detected by a voltage sensor before the battery starts charging, and an OCV is used, which is determined from the voltage detected by a voltage sensor after the battery is fully charged. When using the current integration method, there is always a demand to estimate the full charge capacity of the battery as accurately as possible.

This disclosure has been made to solve the above problems, and the purpose of this disclosure is to improve the accuracy of estimating the full charge capacity of a battery.

(1) A vehicle according to an aspect of the present disclosure is configured to be capable of external charging with power supplied from a charging facility. The vehicle includes a battery, a voltage sensor that detects the voltage of the battery, and a control device that estimates a full charge capacity of the battery based on a first OCV (Open Circuit Voltage) determined from a voltage detected by the voltage sensor before the start of external charging, and a second OCV determined from a 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 will be started after waiting for a first polarization elimination time required to eliminate polarization of the battery that occurred before the start of external charging. When external charging is predicted to be completed by the departure time, the control device waits for the first polarization elimination time before starting 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, while when external charging is predicted not to be completed by the departure time, starts external charging without waiting for the first polarization elimination time.

(2) The control device predicts whether external charging will be completed by the departure time, assuming that external charging is started after waiting for a first depolarization time, and that external charging is then waited for a second depolarization time required to depolarize the battery caused by external charging, after the end of external charging. When external charging is predicted to be completed by the departure time, the control device uses the voltage detected by the voltage sensor after waiting for the second depolarization time as the second OCV.

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

(4) The control device predicts that external charging will be completed by the departure time if the estimated time at which the first polarization elimination time, the battery charging time, and the second polarization elimination time have elapsed is earlier than the departure time, and predicts that external charging will not be completed by the departure time if the estimated time is later than the departure time.

In the above configuration (1), the polarization that occurs before the start of external charging is eliminated by waiting for a first polarization elimination time before the start of external charging. This makes it possible to obtain the first OCV before the start of external charging with high accuracy. In the above configuration (2), the polarization that occurs due to external charging is further eliminated by waiting for a second polarization elimination time after the end of external charging. This makes it possible to obtain the second OCV after the end of external charging with high accuracy. However, waiting as described above is only when it is predicted that external charging of the battery will be completed even if there is waiting. If it is predicted that external charging of the battery will not be completed if there is waiting, external charging is started without waiting, and the reduction in the EV distance of the vehicle is suppressed. Therefore, according to the above configurations (1) to (4), it is possible to improve the estimation accuracy of the full charge capacity of the battery without impairing the convenience of the user.

(5) The control device estimates the departure time based on the learning results regarding the vehicle's past departure times.

(6) The control device obtains the departure time determined by the vehicle user's operation.

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

(7) In a vehicle charging method according to another aspect of the present disclosure, the vehicle is configured to enable external charging of the battery with power supplied from a charging facility. The vehicle is also 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 external charging and a second OCV determined from a 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 will be started after waiting for a polarization 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 waiting for the polarization elimination time before starting external charging 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 polarization 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 polarization elimination time when it is predicted that external charging will not be completed by the departure time.

According to the method (7) above, as with the configuration (1) above, it is possible to improve the accuracy of estimating the full charge capacity of the battery.

The present disclosure makes it possible to improve the accuracy of estimating the full charge capacity of a battery in a vehicle that is configured to allow external charging.

1 is a diagram illustrating a schematic overall configuration of a vehicle according to an embodiment of the present disclosure. 13 is a time chart for explaining a capacity estimation process when there is time to spare before the departure time. 11 is a time chart for explaining a capacity estimation process when there is not much time left until the departure time. 13 is a flowchart showing a processing procedure of a capacity estimation process in the present embodiment. 13 is a flowchart showing a processing procedure of a standby estimation process. 13 is a flowchart showing another example of the processing procedure of the standby estimation process. 13 is a flowchart showing a processing procedure of a non-standby estimation process. 13 is a flowchart showing an example of a processing procedure related to learning of a departure time. FIG. 13 is a diagram illustrating an example of the variation in departure times.

The following describes in detail the embodiments of the present disclosure with reference to the drawings. Note that the same or corresponding parts in the drawings are given the same reference numerals and their description will not be repeated.

[Embodiment]
<System Configuration>
1 is a diagram that illustrates a schematic overall configuration of a vehicle according to an embodiment of the present disclosure. Vehicle 1 is configured to be capable of "plug-in charging" using power supplied from a charging facility (not shown). Vehicle 1 is, for example, an electric vehicle (EV), but the type of vehicle is not particularly limited. Vehicle 1 may also be a plug-in hybrid vehicle (PHV).

The 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 communication device (DCM) 80, and an ECU (Electronic Control Unit) 90.

The battery 10 is a battery pack including multiple cells. Each cell is a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The battery 10 stores power for driving the motor generator 72 and supplies power to the motor generator 72 via the PCU 71. The battery 10 is also charged by receiving the generated power via the PCU 71 when the motor generator 72 is generating power.

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 detection value to the ECU 90.

The SMR 30 is provided on the power line connecting the battery 10 to the PCU 71 and the AC/DC converter 50. The SMR 30 is opened and closed according to commands 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.

The inlet 40 is configured to be connected to a connector (not shown) provided at the end of the charging cable via a mechanical connection. By connecting the inlet 40 to the connector, an electrical connection between the charging equipment and the vehicle 1 is ensured. In addition, the ECU 90 of the vehicle 1 and a control device (not shown) of the charging equipment can transmit and receive various commands and data to and from each other in accordance with a specified communication standard.

The AC/DC converter 50 converts AC power supplied from the charging facility via a charging cable into DC power for charging the battery 10. If 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.

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 is in a state where it can be charged by power from the inlet 40.

The PCU 71 is electrically connected between the SMR 30 and the motor generator 72. The PCU 71 includes a converter and an inverter (neither shown), and drives the motor generator 72 according to commands from the ECU 90.

The motor generator 72 is an AC rotating electric machine, for example a permanent magnet type synchronous motor with a rotor in which a permanent magnet is embedded. The output torque of the motor generator 72 is transmitted to the drive wheels 74 through the power transmission gear 73, causing the vehicle 1 to move. In addition, the motor generator 72 can generate electricity using the rotational force of the drive wheels 74 when the vehicle 1 is braking. The power generated by the motor generator 72 is converted by the PCU 71 into charging power for the battery 10.

The DCM 80 is configured to be capable of two-way communication with a user terminal U (e.g., a smartphone) outside the vehicle 1. This allows the vehicle 1 to accept user operations related to plug-in charging (such as setting the departure time, which will be described later).

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 signals received from each sensor and programs and maps stored in the memory 92. For example, the ECU 90 communicates with a charging facility and controls the SMR 30, the AC/DC converter 50, and the CHR 60 to control plug-in charging of the vehicle 1. The ECU 90 also manages the state of the battery 10 using the monitoring unit 20. In this embodiment, a major process executed by the ECU 90 is a process for estimating the full charge capacity of the battery 10 by utilizing an opportunity for plug-in charging of the vehicle 1. This process is referred to as a "capacity estimation process" and will be described in detail.

The ECU 90 may be divided into multiple 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.

<Capacity Estimation Process>
In the capacity estimation process, the ECU 90 estimates the full charge capacity of the battery 10 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 an integrated value of the current charged to the battery 10 during plug-in charging (current integration method). Here, both the voltage before the start of plug-in charging and the voltage after the end of plug-in charging must be open circuit voltages (OCVs).

However, one of the main anticipated scenarios for plug-in charging is immediately after the user returns home, in which the user drives the vehicle 1 and returns home, and connects the charging cable to the inlet 40 before getting out of the vehicle 1 and going indoors. Then, charging of the battery 10 starts immediately after that. In such a charging scenario, polarization occurs in the battery 10 because discharging associated with the running of the vehicle 1 has just ended. Therefore, the voltage VB detected by the voltage sensor 21 deviates from the OCV by an amount corresponding to the effect of polarization. This can reduce the accuracy of estimating the full charge capacity of the battery 10.

Therefore, in this embodiment, a configuration is adopted in which the accuracy of estimating the full charge capacity is improved by using the voltage VB detected after waiting until the polarization is eliminated. However, if the polarization is uniformly waited until elimination, the completion time of plug-in charging will be delayed accordingly, and there is a possibility that plug-in charging will not be completed by the user's next departure time. As a result, the EV distance of the vehicle 1 will be shortened, and the user's convenience may be impaired. Therefore, in this embodiment, whether to wait until polarization is eliminated is determined taking into consideration whether there is enough time until the user's departure time. More specifically, if it is predicted that plug-in charging will be completed by the user's departure time even if it waits until polarization is eliminated, it is decided to wait until polarization is eliminated. On the other hand, if there is a possibility that plug-in charging will not be completed by the user's departure time if it waits until polarization is eliminated, it is decided to start plug-in charging without waiting for polarization to be eliminated.

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

The vehicle 1, which is initially traveling, arrives at a location where charging equipment is installed (e.g., the user's home) at time ta. The user gets out of the vehicle 1 and connects the charging cable to the inlet 40. The ECU 90 calculates the charging time Tch (in this example, the time required to charge the battery 10 to a fully charged state) and obtains the user's next departure time tb. The method for obtaining the departure time tb will be described in detail later.

Furthermore, the ECU 90 calculates a waiting time before plug-in charging begins. This waiting time is the time required for the polarization that occurs in the battery 10, which has been discharged as the vehicle 1 is traveling, to be eliminated (sufficiently alleviated). Hereinafter, this time will be referred to as the "first polarization elimination time T1."

The ECU 90 also calculates the waiting time after plug-in charging is completed. This waiting time is the time required for the polarization caused in the battery 10 by plug-in charging to be eliminated (sufficiently alleviated). Hereinafter, this time is referred to as the "second polarization elimination time T2."

Assuming that the ECU 90 waits the first polarization elimination time T1 before the start of plug-in charging and waits the second polarization elimination time T2 after plug-in charging is completed, the ECU 90 determines whether plug-in charging of the vehicle 1 will be completed by the departure time tb. 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 "allocable time ΔT" for charging the battery 10 (corresponding to the "estimated time" according to the present disclosure).

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

Figure 3 is a time chart to explain the capacity estimation process when there is not much time left before the departure time. In Figure 3, the assumed control is shown at the top, and the control that is actually executed is shown at the bottom.

In the example shown in FIG. 3, the SOC of the battery 10 is low when the vehicle 1 arrives at the user's home (see time ta) compared to the example shown in FIG. 2, so the required charging time Tch is long. Therefore, when comparing the allocable time ΔT and the required charging time Tch, the allocable time ΔT is shorter than the required charging time Tch. In this case, if there is waiting both before the start of plug-in charging and after the end of plug-in charging, the departure time tb arrives before the plug-in charging of the vehicle 1 is completed. Therefore, the ECU 90 starts plug-in charging of the vehicle 1 without waiting for polarization to be eliminated before starting plug-in charging.

In this way, if it is predicted that plug-in charging will be completed by the time the user's departure time tb arrives even if the ECU 90 waits until the polarization is eliminated prior to the start of plug-in charging, the ECU 90 decides to wait for the polarization to be eliminated. This allows the full charge capacity of the battery 10 to be estimated with high accuracy. In contrast, if it is predicted that plug-in charging will not be completed by the time the departure time tb arrives if the ECU 90 waits until the polarization is eliminated, the ECU 90 decides to start plug-in charging without waiting for the polarization to be eliminated. In other words, the ECU 90 prioritizes ensuring user convenience over highly accurate estimation of the full charge capacity.

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

When the flow chart shown in FIG. 2 starts to be executed, the CHR 60 is open. Therefore, the battery 10 is electrically disconnected from the AC/DC converter 50.

In S1, the ECU 90 determines whether the conditions for updating the full charge capacity C of the battery 10 are met. For example, if a predetermined period of time has passed since the previous estimation of the full charge capacity C of the battery 10, it is determined that the update conditions are met. If the update conditions are met (YES in S1), the ECU 90 acquires the current time ta (S2).

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

In S4, the ECU 90 calculates a first polarization elimination time T1 required to eliminate the polarization caused in the battery 10 due to discharging before 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 is created in which the relationship between the current IB discharged from the battery 10 within the most recent specified time, the temperature TB of the battery 10, and the first polarization elimination time T1 is experimentally obtained 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 temperature TB (measured value) within the most recent specified 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 by a prior experiment, and the time (i.e., a fixed value) may be used as the first polarization elimination time T1.

In S5, the ECU 90 calculates a second polarization elimination time T2 required to eliminate the polarization caused in the battery 10 by plug-in charging. The second polarization elimination time T2 can be calculated using a map, similar to the first polarization elimination time T1. The map defines the relationship between the current IB charged to the battery 10 within the most recent specified time, the temperature TB of the battery 10, and the second polarization elimination time T2. By referring to this map, the ECU 90 can calculate the second polarization elimination time T2 from the charging current IB (planned value for plug-in charging) and temperature TB (predicted value at the time of completion of charging) within the most recent specified time. The second polarization elimination time T2 may also be a fixed value obtained in advance through experiments.

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

In S7, the ECU 90 calculates the allocable time ΔT 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 (see the following formula (1)).
ΔT=(tb-ta)-T1-T2...(1)

In S8, the ECU 90 predicts whether plug-in charging will be completed by the user's departure time tb. More specifically, the ECU 90 compares the required charging time Tch calculated in S3 with the allocable time ΔT calculated in S7. If the allocable time ΔT is equal to or greater than the required charging time Tch (YES in S8), the ECU 90 predicts that plug-in charging will be completed by the user's departure time, and executes a "standby estimation process" that waits for polarization elimination (S9). On the other hand, if the allocable time ΔT is shorter than the required charging time Tch (NO in S8), the ECU 90 predicts that 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 polarization elimination (S10). This ends the series of processes.

In FIG. 4, an example is described in which the required charging time Tch is compared with the allocable time ΔT to predict whether plug-in charging will be completed by the user's departure time tb. However, the method of predicting whether plug-in charging will be completed is not limited to this. For example, the ECU 90 may calculate the time when the first polarization elimination time T1, the required charging time Tch, and the second polarization elimination time T2 have elapsed from the current time ta (the completion time of plug-in charging including waiting before and after plug-in charging), and compare this time with the departure time tb. If the time is earlier than the departure time tb, the ECU 90 predicts that plug-in charging will be completed by the user's departure time tb, whereas if the time is later than the departure time tb, the ECU 90 can predict that plug-in charging will not be completed by the user's departure time tb.

Figure 5 is a flowchart showing the procedure of the standby estimation process. In S101, the ECU 90 determines whether the first polarization elimination time T1 has elapsed since the current time ta. The ECU 90 waits until the first polarization elimination time T1 has elapsed (NO in S101). When the first polarization elimination time T1 has elapsed (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 battery 10 is not being charged or discharged (IR drop amount = 0), so the voltage VB can be approximated as being equal to the OCV of the battery 10. Therefore, the voltage VB at this time is described as "OCV1" (corresponding to the first OCV).

In S103, the ECU 90 closes (ON) the CHR 60 and controls the AC/DC converter 50 to start charging the battery 10. In addition, the ECU 90 starts sequentially accumulating the detection value of the current sensor 22 (current accumulation) as charging of the battery 10 starts.

In S104, the ECU 90 determines whether the end condition for plug-in charging is met. For example, the end condition for plug-in charging is met when the SOC of the battery 10 reaches a target SOC or a predetermined amount of power is charged to the battery 10. When the end condition for plug-in charging is met (YES in S104), the ECU 90 controls the AC/DC converter 50 to end charging of the battery 10 and ends current integration (S105). The ECU 90 also opens (turns off) the CHR 60.

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

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

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

In S110, the ECU 90 estimates the full charge capacity C of the battery 10 based on ΔSOC calculated in S108 and the current integrated value ΔAh calculated in S109. In detail, the full charge capacity C of the battery 10 can be calculated according to the following formula (3) in which the ratio of the charging current value ΔAh to ΔSOC is equal to the ratio of the full charge capacity C to ΔSOC=100%. 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 a capacity maintenance rate Q from the full charge capacity C (Q=C/C0).
C=ΔAh/ΔSOC×100...(3)

Figure 6 is a flowchart showing another example of the processing procedure of the standby estimation process. This flowchart differs from the flowchart of the standby estimation process described in Figure 5 in that it includes a process (S201) of waiting for the first polarization elimination time T1, but does not include a process of waiting for the second polarization elimination time T2 (see S106 in Figure 5). In this way, it is not necessary to set both the first polarization elimination time T1 and the second polarization elimination time T2, and it is possible to set only the first polarization elimination time T1 for waiting for the polarization caused by the discharge of the battery 10 to be eliminated before the start of plug-in charging. In this case, the process of S5 (see Figure 4) for calculating the second polarization elimination time T2 in the capacity estimation process is omitted. In addition, the allocable time ΔT is calculated by ΔT = (tb - ta) - T1.

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

In S206, the ECU 90 calculates the polarization voltage Vp2 occurring in the battery 10 after charging is completed. The polarization voltage Vp2 can be calculated, for example, by using a map that experimentally determines the relationship between the current IB charged into the battery 10 within a specified period of time immediately prior to the end of current integration, the temperature TB of the battery 10, and the polarization voltage Vp2.

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

Then, the ECU 90 controls the AC/DC converter 50 so that charging of the battery 10 is terminated, and terminates current integration (S208). The subsequent processing of S209 to S211 is similar to the processing of S108 to S110 in FIG. 5 (see FIG. 5), and therefore will not be described again.

Figure 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 before the start of current integration from the voltage sensor 21. This voltage VB is referred to as "VB1."

In S302, the ECU 90 calculates the polarization voltage Vp1 occurring in the battery 10 after the end of discharging associated with the running of the vehicle 1. The polarization voltage Vp1 can be calculated using a map that experimentally determines the relationship between the current IB discharged from the battery 10 within the most recent specified time period, the temperature TB of the battery 10, and the polarization voltage Vp1.

In S303, the ECU 90 calculates the OCV of the battery 10 before the start of current integration. This OCV is referred to as "OCV1." The 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)

The subsequent steps S304 to S312 are similar to the corresponding steps S103 to S110 and S203 to S211 in the standby estimation process (see FIG. 5 or FIG. 6), so detailed description will not be repeated.

Note that FIG. 7 describes an example in which the full charge capacity C is estimated even when there is no time to wait until polarization is eliminated (when plug-in charging is predicted not to be completed by departure time tb). However, estimating the full charge capacity C may be limited to cases where there is time to wait for polarization to be eliminated, and estimation of the full charge capacity C may not be performed when there is no time to spare.

<Learning departure times>
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.

Figure 8 is a flowchart showing an example of a processing procedure for learning 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 set as the departure time.

In S402, the ECU 90 determines whether the number of times the departure time has been recorded exceeds a predetermined number. If the number of times the departure time has been recorded 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).

Figure 9 is a diagram showing an example of the variability in departure times. In Figure 9, the horizontal axis represents the number of times the departure time was recorded, and the vertical axis represents the departure time. With reference to Figures 8 and 9, in this example, a learning section is set based on the past departure times of vehicle 1. For example, a section with a predetermined time width (e.g., 40 minutes) before and after the average departure time of vehicle 1 can be set as the learning section. Also, the learning section may be set taking into account sections where the departure times vary before and after the average departure time. For example, a section of the average departure time ±2σ (σ: standard deviation of departure time) can be set as the learning section.

If the departure time is within the learning interval (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 interval 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).

If the number of times the departure time has been recorded does not exceed the predetermined number (NO in S402), the ECU 90 skips the process of S403. In other words, the ECU 90 learns the recorded departure time without discarding it.

As described above, in this embodiment, the polarization that occurs in the battery 10 as the vehicle 1 travels is eliminated by waiting for the first polarization elimination time T1 before plug-in charging begins. This makes it possible to obtain the voltage before charging begins (OCV1) with high accuracy. In addition, the polarization that occurs in the battery 10 as the vehicle 1 plug-in charges the vehicle 1, is eliminated by waiting for the second polarization elimination time T2 after plug-in charging ends. This makes it possible to obtain the voltage after charging ends (OCV2) with high accuracy. Therefore, it is possible to improve the estimation accuracy of the full charge capacity C calculated using OCV1 and OCV2.

However, waiting before starting charging (and after charging is completed) is the case where plug-in charging is predicted to be completed even if waiting for the first polarization elimination time T1 (and the second polarization elimination time T2). If it is predicted that plug-in charging will not be completed if waiting for the first polarization elimination time T1 (and the second polarization elimination time T2), securing power for battery 10 is prioritized over improving the estimation accuracy of full charge capacity C. This makes it possible to suppress a decrease in user convenience due to a shortened EV distance of vehicle 1. Therefore, according to this embodiment, it is possible to improve the estimation accuracy of full charge capacity C of battery 10 without compromising user convenience.

In this embodiment, the vehicle 1 is described as being plugged in for charging. However, the manner of external charging of the vehicle 1 is not limited to plugging in. The vehicle 1 may be configured to be capable of "contactless charging," in which power is transmitted contactlessly from a power transmitting device buried in the ground to an on-board power receiving device.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is indicated by the claims rather than the description of the embodiments above, and is intended to include all modifications within the meaning and scope of the claims.

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 (6)

A vehicle configured to be externally charged using power supplied from a charging facility,
A battery;
a voltage sensor for detecting a voltage of the battery;
a control device that estimates a full charge capacity of the battery based on a first OCV determined from a voltage detected by the 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,
The control device includes:
calculating the first polarization elimination time from a current discharged from the battery within a first time period prior to the external charging, the temperature of the battery, and a first polarization elimination time required to eliminate polarization of the battery that occurred before the start of the external charging, by referring to a map in which the relationship is obtained between the current and the temperature;
calculating the second polarization elimination time from the current and the temperature by referring to a map in which a relationship is obtained between a current charged into the battery within a second time period prior to the external charging, a temperature of the battery, and a second polarization elimination time required to eliminate the polarization of the battery caused by the external charging;
predicting whether the external charging will be completed by a departure time of the vehicle , assuming that the external charging is started after waiting for the first polarization elimination time and that the external charging is terminated after waiting for the second polarization elimination time;
when it is predicted that the external charging will be completed by the departure time, waiting for the first polarization elimination time and then starting the external charging, and estimating a full charge capacity of the battery by using a voltage detected by the voltage sensor after waiting for the first polarization elimination time and before starting the external charging as the first OCV and using a voltage detected by the voltage sensor after waiting for the second polarization elimination time as the second OCV ;
When it is predicted that the external charging will not be completed by the departure time, the external charging is started without waiting for the first depolarization time. The control device includes:
predicting that the external charging will be completed by the departure time when an estimated time obtained by subtracting the first and second polarization elimination times from the time until the departure time is longer than a required charging time for the battery;
The vehicle according to claim 1 , wherein a prediction is made that the external charging will not be completed by the departure time when the estimated time is shorter than the required charging time. The control device includes:
predicting that the external charging will be completed by the departure time when an estimated time at which the first polarization elimination time, the charging time required for the battery, and the second polarization elimination time have elapsed is earlier than the departure time;
The vehicle according to claim 1 , wherein, when the estimated time is later than the departure time, it is predicted that the external charging will not be completed by the departure time. The vehicle according to any one of claims 1 to 3 , wherein the control device estimates the departure time based on a learning result regarding past departure times of the vehicle. The vehicle according to claim 1 , wherein the control device acquires the departure time determined by an operation of a user of the vehicle. A charging method for a vehicle configured to enable external charging of a battery by power supplied from a charging facility, comprising:
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,
The charging method includes:
predicting whether the external charging will be completed by a departure time of the vehicle, assuming that the external charging is started after waiting for a first polarization elimination time required to eliminate polarization of the battery that occurred before the start of the external charging, and that the external charging is started after waiting for a second polarization elimination time required to eliminate polarization of the battery that occurred by the external charging;
when the external charging is predicted to be completed by the departure time, waiting for the polarization elimination time and then starting the external charging, and estimating a full charge capacity of the battery by using a voltage detected by the voltage sensor after waiting for the first polarization elimination time and before the start of the external charging as the first OCV and using a voltage detected by the voltage sensor after waiting for the second polarization elimination time as the second OCV;
when it is predicted that the external charging will not be completed by the departure time, starting the external charging without waiting for the first polarization depolarization time ;
The predicting step includes:
calculating the first polarization elimination time from a current discharged from the battery within a first time period prior to the external charging, the temperature of the battery, and the first polarization elimination time by referring to a map in which a relationship between the current and the temperature is obtained;
and calculating the second polarization elimination time from the current charged to the battery within a second time period prior to the external charging, the temperature of the battery, and the second polarization elimination time by referring to a map in which a relationship is obtained between the current and the temperature .

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