Electric vehicles

Abstract

This invention provides an electric vehicle that can suppress the deterioration of the accuracy of estimating the full charge capacity by estimating the full charge capacity based on the OCV (Operating Temperature) before and after vehicle operation. [Solution] The electric vehicle 1 comprises a power storage device 40, a drive device 10, a relay 14, a voltage sensor 51 for measuring the voltage of the power storage device 40, a current sensor 52 for measuring the charge and discharge current of the power storage device 40, and a control unit 20. The control unit 20 acquires a first OCV when the relay 14 is OFF. The control unit 20 acquires a second OCV when the relay is turned OFF after being turned ON at least once. Based on the measurement values ​​from the current sensor 52, the control unit 20 calculates the integrated current value of the power storage device 40 from the time the first OCV is acquired until the second OCV is acquired. Based on the integrated current value, the first OCV, and the second OCV, the control unit 20 calculates the full charge capacity of the power storage device 40.

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle.

Background Art

[0002] Conventionally, various methods have been proposed for estimating the full charge capacity of a battery mounted on a vehicle. Japanese Patent Application Laid-Open No. 2008-261669 (Patent Document 1) discloses a method of calculating the full charge capacity of a battery from a first open circuit voltage (hereinafter referred to as the first OCV) before the start of plug-in charging, a second open circuit voltage (hereinafter referred to as the second OCV) after the end of plug-in charging, and a current integration value that is the difference in battery capacity between the first OCV and the second OCV.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when the user starts plug-in charging immediately after the vehicle has traveled, the full charge capacity is calculated based on the first OCV including the influence of voltage drop due to polarization. As a result, the estimation accuracy of the full charge capacity calculated based on the first OCV including the influence of voltage drop due to polarization is inferior to the estimation accuracy of the full charge capacity calculated based on the first OCV from which the influence of voltage drop due to polarization has been removed. A method of estimating the first OCV considering polarization immediately after traveling is disclosed, for example, in Japanese Patent Application Laid-Open No. 2022-150523 (Patent Document 2). However, when the waiting time from immediately after traveling to plug-in charging is short, the estimation accuracy of the first OCV considering polarization is poor, and an accurate estimation of the full charge capacity cannot be performed.

[0005] The inventors confirmed that there are electric vehicles that remain parked without being plugged in and charged after driving, such as when going out. The inventors then considered calculating the full charge capacity based on the OCV (Overcurrent Value) acquired before and after the vehicle's operation.

[0006] This disclosure is made to solve the above problems, and its purpose is to provide an electric vehicle that can suppress deterioration in the accuracy of estimating the full charge capacity by estimating the full charge capacity based on the OCV before and after vehicle operation. [Means for solving the problem]

[0007] The electric vehicle relating to the first aspect of this disclosure comprises an electric energy storage device mounted on the electric vehicle, a drive device that generates driving force using power supplied from the electric energy storage device, a relay provided between the electric energy storage device and the drive device, a voltage sensor that measures the voltage of the electric energy storage device, a current sensor that measures the charging and discharging current of the electric energy storage device, and a control unit. The control unit acquires a first OCV when the relay is OFF. The control unit acquires a second OCV when the relay is OFF after being turned ON at least once. Based on the measurements from the current sensor, the control unit calculates the integrated current value of the electric energy storage device from the time the first OCV was acquired until the second OCV was acquired. Based on the integrated current value, the first OCV, and the second OCV, the control unit calculates the full charge capacity of the electric energy storage device.

[0008] The control unit of the electric vehicle relating to the first aspect of this disclosure may acquire the second OCV after the relay is turned OFF and after the first period has elapsed.

[0009] The control unit of the electric vehicle relating to the first aspect of this disclosure may acquire the first OCV again after a second period has elapsed since acquiring the first OCV.

[0010] The control unit of the electric vehicle relating to the first aspect of this disclosure may acquire a first OCV after the electric vehicle has finished plug-in charging.

[0011] The control unit of the electric vehicle relating to the first aspect of this disclosure may acquire the first OCV after the electric vehicle has finished plugging in and after the third period has elapsed.

[0012] The electric vehicle according to the second aspect of this disclosure may have a current sensor located outside the energy storage device. The energy storage device may include an energy storage module. The control unit may store information about the internal current flowing within the energy storage module. The control unit may calculate the full charge capacity of the energy storage device based on the internal current, the integrated current value, the first OCV, and the second OCV. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of an electric vehicle according to an embodiment of the present disclosure. [Figure 2] This is a control flow diagram of an electric vehicle according to an embodiment of the present disclosure. [Figure 3] This is an example of a method for estimating the full charge capacity performed by an electric vehicle according to the embodiments of this disclosure. [Figure 4] This is a schematic diagram of an electric vehicle according to an embodiment of the present disclosure. [Figure 5] This is a control flow diagram of an electric vehicle according to Embodiment 2. [Figure 6] In Embodiment 2, the OCV and current values ​​of the energy storage device 40 and the open / closed state of the SMR14 are shown for each time point. [Modes for carrying out the invention]

[0014] Embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions will not be repeated. <Outline configuration of electric vehicles> Figure 1 is a diagram showing a schematic configuration of an electric vehicle according to an embodiment of the present disclosure.

[0015] The electric vehicle 1 is, for example, an electric car. The electric vehicle 1 includes a drive device 10, a system main relay (SMR) 14, an ECU 20, a power storage device 40, a voltage sensor 51, a current sensor 52, and a temperature sensor 53. The ECU 20 is communicatively formed with a PCU 13, the SMR 14, the voltage sensor 51, the current sensor 52, the temperature sensor 53, which will be described later.

[0016] The drive device 10 is configured to generate a running driving force by the electric power supplied from the power storage device 40. The drive device 10 includes a motor generator (MG) 11 which is a rotary electric machine, drive wheels 12, and a power control unit (PCU) 13.

[0017] The MG 11 is, for example, an embedded structure permanent magnet synchronous motor (IPM motor), and has functions as an electric motor (motor) and a generator (generator). The output torque of the MG 11 is transmitted to the drive wheels 12 via a power transmission device including a reduction gear, a differential device, and the like.

[0018] During braking of the electric vehicle 1, the MG 11 is driven by the drive wheels 12, and the MG 11 operates as a generator. Thereby, the MG 11 also functions as a braking device that performs regenerative braking to convert the kinetic energy of the electric vehicle 1 into electric power. The regenerative electric power generated by the regenerative braking force in the MG 11 is stored in the power storage device 40.

[0019] The PCU 13 is a power conversion device that converts electric power bidirectionally between the MG 11 and the power storage device 40. The PCU 13 includes, for example, an inverter and a converter that operate based on a control signal from the ECU 20. The converter boosts the voltage supplied from the power storage device 40 during discharge of the power storage device 40 and supplies it to the inverter. The inverter converts the DC power supplied from the converter into AC power and drives the MG 11. Note that the PCU 13 may have a configuration in which the converter is omitted.

[0020] SMR14 is provided between the power storage device 40 and the drive device 10. SMR14 is electrically connected to the power line connecting the power storage device 40 and the drive device 10. When SMR14 is closed (ON) according to the control signal from the ECU20 (i.e., in a conductive state), power can be exchanged between the power storage device 40 and the PCU13. On the other hand, when SMR14 is opened (OFF) according to the control signal from the ECU20 (i.e., in a cut-off state), the electrical connection between the power storage device 40 and the PCU13 is cut off. SMR14 closes (turns ON), for example, when the ignition power supply of the electric vehicle 1 is turned ON. SMR14 functions as a protection device during the driving of the electric vehicle 1. Note that SMR14 is an example of the "relay" of the present disclosure.

[0021] ECU20 includes a processor 21, a memory 22, and a storage 23. The processor 21 is an arithmetic device such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The memory 22 is a volatile memory (working memory) such as a RAM (Random Access Memory). The storage 23 is a rewritable non-volatile memory such as a flash memory. The storage 23 stores a system program including an OS (Operating System) and a control program including computer-readable code necessary for control operations. The processor 21 reads out the system program and the control program, expands them in the memory 22, and executes them to realize various processes. ECU20 stores the voltage information acquired from the voltage sensor 51 and the current information acquired from the current sensor 52, which will be described later, together with the time information. ECU20 may be divided into a plurality of ECUs for each function. Note that ECU20 is an example of the "control unit" of the present disclosure.

[0022] The energy storage device 40 is mounted on the electric vehicle 1. The energy storage device 40 has a battery pack 41. The battery pack 41 has a plurality of energy storage modules 42. The plurality of energy storage modules 42 are electrically connected in series. The energy storage modules 42 have a plurality of energy storage cells 43. The plurality of energy storage cells 43 are electrically connected in series. The energy storage cells 43 are secondary batteries such as nickel-metal hydride batteries or lithium-ion batteries. A secondary battery is, for example, a battery that has a liquid electrolyte between a positive electrode and a negative electrode. The energy storage device 40 has an equalization circuit 44 provided in each of the plurality of energy storage cells 43 and a monitoring IC 45 provided in each of the plurality of energy storage cells 43. The equalization circuit 44 has a discharge resistor. The equalization circuit 44 is used, for example, to equalize the energy storage capacity of each of the plurality of energy storage cells 43. The monitoring IC 45 has a voltage sensor 51 and a temperature sensor 53. The monitoring IC 45 is connected in parallel to each of the multiple energy storage cells 43, and is configured to measure the voltage and temperature of each energy storage cell 43 and output the measurement results to the ECU 20.

[0023] The voltage sensor 51 is configured to measure the voltage between the terminals of the battery pack 41 and output the measurement result to the ECU 20. Furthermore, the voltage sensor 51 is configured to measure the voltage of each of the multiple energy storage cells 43 and output the measurement result to the ECU 20.

[0024] The current sensor 52 is located outside the energy storage device 40. The current sensor 52 is configured to measure the charge and discharge current of the battery pack 41 and output the measurement result to the ECU 20. For example, when the battery pack 41 is discharging, the current sensor 52 can use a positive value as the current value measured by the current sensor 52. Also, for example, when the battery pack 41 is charging, the current sensor 52 can use a negative value as the current value measured by the current sensor 52.

[0025] The temperature sensor 53 is configured to measure the temperature of multiple energy storage cells 43 and output the measurement results to the ECU 20. <Control flow of electric vehicles> Next, with reference to Figure 2, the control flow for calculating the full charge capacity performed by the electric vehicle 1 will be explained.

[0026] In step S10 shown in Figure 2, the ECU20 checks whether the SMR14 is open (OFF). If the SMR14 is OFF (Yes in step S10), the ECU20 proceeds to step S15. If it is not OFF (No in step S10), the ECU20 processes step S10 again.

[0027] In step S15, the ECU20 acquires the first OCV. More specifically, the ECU20 stores the voltage information acquired from the voltage sensor 51 as the first OCV. After that, the ECU20 proceeds to step S20.

[0028] In step S20, ECU20 checks whether SMR14 is closed (ON). If SMR14 is ON (Yes in step S20), ECU20 proceeds to step S25. If SMR14 is not ON (No in step S20), ECU20 proceeds to step S45.

[0029] In step S25, ECU20 checks if SMR14 is OFF. If SMR14 is OFF (Yes in step S25), ECU20 proceeds to step S30. If SMR14 is not OFF (No in step S25), ECU20 processes step S25 again.

[0030] In step S30, ECU20 checks if the first period P1 has elapsed. Here, the first period P1 is the period from step S25, when ECU20 confirmed that SMR14 is OFF. If the first period P1 has elapsed after the processing in step S25 (Yes in step S30), ECU20 proceeds to step S35. If the first period P1 has not elapsed after the processing in step S25 (No in step S30), ECU20 processes step S30 again.

[0031] In step S35, the ECU20 acquires the second OCV. More specifically, the ECU20 stores the voltage information acquired from the voltage sensor 51 as the second OCV. After that, the ECU20 proceeds to step S40.

[0032] In step S40, the ECU20 calculates the full charge capacity. More specifically, the ECU20 calculates the full charge capacity of the battery pack 41 based on the first OCV, the second OCV, and the integrated current value. Here, the integrated current value is the integrated value of the charge and discharge currents of the battery pack 41 from the time the first OCV is acquired until the time the second OCV is acquired. The ECU20 calculates the integrated current value based on the measurement value output from the current sensor 52. After that, the ECU20 proceeds to step S20.

[0033] In step S45, ECU20 checks whether the second period P2 has elapsed. Here, the second period P2 is the period since ECU20 acquired the first OCV in step S15. The second period P2 is, for example, a period of 2 days to 1 week. If the second period P2 has elapsed since acquiring the first OCV in step S45 (Yes in step S45), ECU20 proceeds to step S50. If the second period P2 has not elapsed since acquiring the first OCV in step S45 (No in step S45), ECU20 proceeds to step S60.

[0034] In step S50, ECU20 checks if SMR14 is OFF. If SMR14 is OFF (Yes in step S50), ECU20 proceeds to step S55. If SMR14 is not OFF (No in step S50), ECU20 processes step S50 again.

[0035] In step S55, the ECU20 checks if the first period P1 has elapsed. Here, the first period P1 is the period from step S50, when the ECU20 confirmed that the SMR14 is OFF. If the first period P1 has elapsed after the processing in step S50 (Yes in step S55), the ECU20 proceeds to step S80. If the first period P1 has not elapsed after the processing in step S50 (No in step S55), the ECU20 processes step S55 again.

[0036] In step S60, the ECU20 checks whether the electric vehicle 1 has started plug-in charging. If the electric vehicle 1 has started plug-in charging (Yes in step S60), the ECU20 proceeds to step S65. If the electric vehicle 1 has not started plug-in charging (No in step S60), the ECU20 processes step S20 again.

[0037] In step S65, the ECU20 checks whether plug-in charging of electric vehicle 1 is complete. If plug-in charging of electric vehicle 1 is complete (No in step S65), the ECU20 proceeds to step S70. If plug-in charging of electric vehicle 1 is not complete (No in step S65), the ECU20 processes step S65 again.

[0038] In step S70, the ECU20 checks whether the third period P3 has elapsed. Here, the third period P3 is the period from step S65, when it is confirmed that plug-in charging of the electric vehicle 1 has finished. If the third period P3 has elapsed since step S65, when it is confirmed that plug-in charging of the electric vehicle 1 has finished (Yes in step S70), the ECU20 proceeds to step S75. If the third period P3 has not elapsed since step S70, when it is confirmed that plug-in charging of the electric vehicle 1 has finished (No in step S70), the ECU20 processes step S70 again.

[0039] In step S75, ECU20 checks if SMR14 is OFF. If SMR14 is OFF (Yes in step S75), ECU20 proceeds to step S80. If SMR14 is not OFF (No in step S75), ECU20 processes step S75 again.

[0040] In step S80, the ECU20 acquires the first OCV. More specifically, the ECU20 stores the voltage information acquired from the voltage sensor 51 as the first OCV. If the ECU20 already has the first OCV stored, the ECU20 overwrites the existing first OCV information with the first OCV information acquired in step S80. After that, the ECU20 proceeds to step S20.

[0041] According to the control flow shown in Figure 2, the ECU 20 of the electric vehicle 1 according to the embodiment of this disclosure estimates the full charge capacity of the battery pack 41. More specifically, in step S15, the ECU 20 acquires a first OCV when the SMR 14 is OFF. Thereafter, after the SMR 14 has been turned ON and OFF at least once, that is, after the ECU 20 has processed steps S20 and S25, it acquires a second OCV. Then, the ECU 20 estimates the full charge capacity of the battery pack 41 based on the first OCV, the second OCV, and the integrated current value. With this estimation method, the electric vehicle 1 can estimate the full charge capacity of the battery pack 41 based on the OCV acquired before and after vehicle operation.

[0042] In this method for estimating full charge capacity, the ECU 20 acquires a second OCV after the SMR14 is turned OFF and after the first period P1 has elapsed (after step S30 processing). This allows the ECU 20 to acquire the OCV after the polarization generated by the discharge current due to driving has been resolved. As a result, the full charge capacity can be estimated based on the OCV with the effect of polarization eliminated, thus suppressing a deterioration in the accuracy of the full charge capacity estimation.

[0043] Here, the first period P1 is, for example, 30 minutes or 1 hour. The ECU 20 stores a map showing the relationship between the temperature of the energy storage cell 43 and the depolarization time, and may select the first period P1 based on the temperature information of the energy storage cell 43 measured by the temperature sensor 53.

[0044] The battery pack 41 consumes power through self-discharge and dark current even when in standby mode. As time passes since the first OCV acquisition, the amount of power consumed due to self-discharge and dark current increases. This power consumption cannot be calculated from the voltage sensor 51 and the current sensor 52. As a result, the accuracy of estimating the full charge capacity deteriorates as time passes since the first OCV acquisition. In the control flow shown in Figure 2, the ECU 20 acquires the first OCV again after the second period P2 has elapsed since the first OCV acquisition. This makes it possible to suppress the deterioration of estimation accuracy due to the increase in power consumption due to self-discharge and dark current each time the second period P2 has elapsed. The second period P2 is, for example, a period from 2 to 10 days.

[0045] Conventionally, the full charge capacity was estimated from the OCV and charging current before and after plug-in charging. However, if plug-in charging is started immediately after driving, the OCV at the start of plug-in charging has not yet been cleared of the polarization that occurred during driving, making it difficult to estimate the full charge capacity with high accuracy. Therefore, in the control flow shown in Figure 2, when the electric vehicle 1 starts plug-in charging, the ECU 20 acquires the first OCV again after plug-in charging is completed (step S80), and then acquires the second OCV (step S35). This makes it possible to suppress the deterioration of the accuracy of the full charge capacity estimation even when plug-in charging is started immediately after driving.

[0046] In addition, the ECU20 acquires the first OCV after plug-in charging is complete and the third period P3 has elapsed (after step S70 processing). This allows the ECU20 to acquire the OCV after the polarization generated by the charging current during plug-in charging has been resolved. As a result, the full charge capacity can be estimated based on the OCV excluding the effect of polarization, thus suppressing a deterioration in the accuracy of the full charge capacity estimation.

[0047] Here, the third period P3 is, for example, 30 minutes or 1 hour. The ECU 20 has a map showing the relationship between the temperature of the energy storage cell 43 and the depolarization time, and may select the third period P3 based on the temperature information of the energy storage cell 43 measured by the temperature sensor 53.

[0048] The estimation of full charge capacity in this disclosure is calculated based on the first OCV, the second OCV, and the integrated current value, but this disclosure is not limited thereto. The estimation of full charge capacity may be calculated, for example, based on the first OCV, the second OCV, the integrated current value, and the internal current. The internal current is the internal current flowing within the energy storage module 42. More specifically, the internal current includes the self-discharge current of the multiple energy storage cells 43, the discharge current flowing through the discharge resistors of the equalization circuit 44 for equalizing the multiple energy storage cells 43, and the current supplied from each of the multiple energy storage cells 42 to the monitoring IC 45. The ECU 20 may store information on the internal current in advance and calculate the amount of power consumed based on the internal current between the first OCV and the second OCV. The ECU20 can suppress deterioration in the accuracy of estimating the full charge capacity by estimating the full charge capacity based on the first OCV, the second OCV, and the total power consumption, which is the sum of the power consumption amount based on the internal current and the integrated current value.

[0049] Information based on internal current refers to the power consumption of the battery pack 41 consumed by the internal current. The power consumption of the battery pack 41 consumed by the internal current includes, for example, information on power consumption based on the relationship between the State of Charge (SOC) and self-discharge current of each of the multiple energy storage cells 43, information on power consumption based on the relationship between the State of Health (SOH) and self-discharge current of each of the multiple energy storage cells 43, and information on power consumption based on the relationship between the temperature and self-discharge current of each of the multiple energy storage cells 43. Furthermore, it also includes information on the power consumption consumed by the monitoring IC 45 in the energy storage device 40, and information on power consumption based on the relationship between the variation in the SOC of each of the multiple energy storage cells 43 and the discharge current flowing through the discharge resistor to equalize the SOC of each of the multiple energy storage cells 43. <Example of Estimating Full Charge Capacity> Figure 3 shows the OCV and current values ​​of the energy storage device 40, and the open / closed state of the SMR14 at each time point. Based on the example shown in Figure 3, a specific example of how the electric vehicle 1 calculates its full charge capacity is shown.

[0050] At time t1, electric vehicle 1 finished plug-in charging. ECU 20 acquired the first OCVa after the third period P3 had elapsed from time t1. At time t2, electric vehicle 1 turned on SMR14 and started driving. At time t3, electric vehicle 1 turned off SMR14 and ended driving. ECU 20 acquired the second OCVa after the first period P1 had elapsed from time t3. Then, ECU 20 calculated the full charge capacity of the battery pack 41 based on the first OCVa, the second OCVa, and the accumulated current value from the acquisition of the first OCVa to the acquisition of the second OCVa.

[0051] At time t4, electric vehicle 1 turned SMR14 ON again and started running. At time t5, electric vehicle 1 turned SMR14 OFF and stopped running. ECU20 acquired the second OCVb at the end of the first period P1 from time t5. ECU20 then calculated the full charge capacity of the battery pack 41 based on the first OCVa, the second OCVb, and the cumulative current value from the acquisition of the first OCVa to the acquisition of the second OCVb.

[0052] At time t6, electric vehicle 1 turned SMR14 ON again and started running. At time t8, electric vehicle 1 turned SMR14 OFF and stopped running. ECU20 acquired the second OCVc at the time P1 of the first period from time t8. ECU20 then calculated the full charge capacity of the battery pack 41 based on the first OCVa, the second OCVc, and the cumulative current value from the acquisition of the first OCVa to the acquisition of the second OCVc.

[0053] At time t9, immediately after calculating the full charge capacity, ECU20 confirmed that the second period P2 had elapsed since the acquisition of the first OCVa. ECU20 confirmed that SMR14 was OFF and that the first period P1 had elapsed since time t8 at time t9, and stored the OCV at the time of the elapsed period P1 from time t8 as the first OCVb.

[0054] At time t10, electric vehicle 1 turned on the SMR14 again and started moving. Subsequently, as electric vehicle 1 finished moving, ECU20 acquired the second OCV again. ECU20 calculates the full charge capacity of the battery pack 41 based on the first OCVb, the second OCV acquired again, and the cumulative current value from the time the first OCVb was acquired until the second OCV was acquired again.

[0055] In the embodiment of this disclosure, the ECU 20 acquires a second OCV each time the electric vehicle 1 finishes driving. This increases the difference between the first OCV and the second OCV, which are the basis for calculating the full charge capacity, thereby suppressing the influence of polarization and other factors on the estimation accuracy. As a result, deterioration in the estimation accuracy of the full charge capacity can be suppressed. (Embodiment 2) The electric vehicle 1A according to Embodiment 2 will be described using Figure 4 and other figures. In Figure 4 and other figures, components that are the same or substantially the same as those shown in Figures 1 to 3 are denoted by the same reference numerals, and detailed descriptions may be omitted.

[0056] The electric vehicle 1A further comprises a power receiving unit 30 and an IG button 35. The IG button 35 is a button that the user uses to start the electric vehicle 1A. When the user turns on the IG button 35, the SMR 14 and the PCU 13 are also turned on. This makes the electric vehicle 1A ready to run. When the IG button 35 is turned off, the SMR 14 and PCU 13 are turned off.

[0057] The power receiving unit 30 includes an inlet 31, a charging device 32, and a charging relay 33. The inlet 31 is formed to be connectable to a charging inlet of a charging station located outside the electric vehicle 1A.

[0058] When the charging connector is connected to the inlet 31, the ECU 20 detects the connection of the charging connector and turns on the charging relay 33 and the SMR 14. Meanwhile, while the charging connector is connected to the inlet 31, the PCU 13 remains in the OFF state.

[0059] The charging device 32 converts the power supplied from the inlet 31 and supplies power to the energy storage device 40. The charging device 32 may be, for example, an AC / DC converter that converts the AC power supplied to the inlet 31 to DC power, or a converter that adjusts the voltage of the DC power supplied to the inlet 31 and supplies it to the power receiving unit 30. In other words, in this embodiment, the charging method for the electric vehicle 1A may be either an AC charging method or a DC charging method. Furthermore, the charging device 32 is not an essential component.

[0060] Furthermore, when the user presses the IG button 35 and the IG button 35 turns ON, the charging relay 33 remains in the OFF state.

[0061] In the example shown in Figure 4, the charging device 32 is connected between the PCU 13 and the SMR 14. Note that the configuration of electric vehicle 1A is substantially the same as that of electric vehicle 1, except for the power receiving unit 30.

[0062] This section describes the case in which a charging plug is connected to the power receiving unit 30 of the electric vehicle 1A to charge the energy storage device 40.

[0063] When charging the energy storage device 40, the charging plug is connected to the power receiving unit 30. When the charging plug is connected to the power receiving unit 30, the PCU 13 turns OFF, and the SMR 14 and charging relay 33 turn ON. Power is then supplied to the energy storage device 40 through the charging plug, the inlet 31, the charging device 32, the charging relay 33, and the SMR 14.

[0064] For example, when the State of Charge (SOC) of the energy storage device 40 reaches a target SOC set within the range of 80% to 100%, charging stops and the SMR 14 and charging relay 33 are turned OFF.

[0065] After charging is complete, when the electric vehicle 1A is to run, the charging plug is removed from the power receiving unit 30, and then the user turns on the IG button 35, which turns on the SMR14 and makes the electric vehicle 1A ready to run.

[0066] Figure 5 is a control flow diagram of an electric vehicle according to Embodiment 2. ECU20 determines whether SMR14 is ON (step S100). Before SMR14 is turned ON, the IG button 35 is turned ON by the user.

[0067] If ECU20 determines that SMR14 is OFF (NO in step S100), it waits until SMR14 is turned ON. If ECU20 determines that SMR14 is ON (YES in ST100), ECU20 determines whether the State of Charge (SOC) of the energy storage device 40 is greater than the threshold TH1 (step S110). The threshold TH1 can be set to various thresholds, for example, from 70% to 90%. Generally, once charging by the power receiving unit 30 is complete, the SOC of the energy storage device 40 is 80% or more. Therefore, the threshold TH1 may be set to 80%.

[0068] If ECU20 determines that SOC is greater than threshold TH1 (YES in step S110), ECU20 determines whether it has already stored the first OCV (step S120). If ECU20 determines that it has not stored the first OCV (NO in step S120), ECU20 acquires the first OCV and stores the acquired first OCV (step S130).

[0069] For example, when a charging plug is connected to the power receiving unit 30, and the energy storage device 40 is charged by the power supplied from the power receiving unit 30, and the SOC of the energy storage device 40 is greater than the threshold TH1, the ECU 20 acquires the first OCV.

[0070] ECU20 determines whether SMR14 is OFF (S140). Note that in step S100 above, SMR14 was ON, and then SMR14 is OFF. Therefore, in step S140, for SMR14 to be OFF, the user must press the IG button 35 to turn it OFF.

[0071] If ECU20 determines that SMR14 is not OFF (NO in S140), ECU20 will wait until SMR14 is turned OFF.

[0072] If ECU20 determines that SMR14 is OFF (YES in step S140), ECU20 waits until the first period has elapsed since SMR14 was turned OFF (step S150).

[0073] When ECU20 determines that the first period has elapsed (YES in step S150), ECU20 acquires the OCV (step S160).

[0074] If an OCV is obtained in step S160 for the first time after obtaining the first OCV in step S130, then that OCV is the "second OCV".

[0075] The ECU20 waits until the SMR14 is turned ON (step S170). When the ECU20 determines that the SMR14 is ON (YES in step S170), it calculates the full charge capacity based on the first OCV, the OCV acquired in step S160, and the cumulative current of the energy storage device 40 from the time the first OCV was acquired until the time the OCV was acquired in step S160 (step S180). The ECU20 then stores the calculated full charge capacity.

[0076] ECU20 determines whether the difference between the first OCV and the OCV obtained in step S160 is greater than the threshold TH2 (step S200).

[0077] If the ECU20 determines that the difference between the first OCV and the OCV obtained in step S160 is greater than the threshold TH2, it updates the full charge capacity (step S210).

[0078] Then, ECU20 determines whether electric vehicle 1A has performed plug-in charging (ST210). Furthermore, if ECU20 determines that the difference between the first OCV and the OCV obtained in step S160 is less than or equal to the threshold TH2 (NO in step S200), ECU20 determines whether electric vehicle 1A has performed plug-in charging.

[0079] If ECU20 determines that electric vehicle 1A is not performing plug-in charging (NO in step S220), ECU20 returns to step S140. Furthermore, if ECU20 determines in step S110 that the SOC is below the threshold TH1 (NO in step S110), ECU20 processes step S140.

[0080] When ECU20 determines that electric vehicle 1A has performed plug-in charging (YES in step S210), ECU20 deletes the first OCV from memory (step S220). Then, in step S300, ECU20's processing returns to step S100.

[0081] Next, I will briefly explain what happens when the ECU20 process returns to step S100.

[0082] If ECU20 determines in step ST110 that the SOC is greater than the threshold TH1 (YES in step S110), ECU20 determines whether it has acquired the first OCV. In this case, if it determines in step S210 of the first processing that plug-in charging has not been performed, the first OCV is not deleted in step S220, and ECU20 retains the first OCV.

[0083] Therefore, ECU20 determines "NO" in step S120, and the processing of ECU20 proceeds to step S140.

[0084] Subsequently, if SMR14 is OFF (YES in step S140) and ECU20 determines that the first period has elapsed (YES in step S150), ECU20 acquires the OCV (step S160). In this second process, the acquired OCV is the "third OCV".

[0085] In step S180, the ECU20 calculates the full charge capacity based on the first OCV, the third OCV acquired in step S160, and the integrated current value of the energy storage device 40 from the time the first OCV was acquired until the third OCV was acquired.

[0086] Then, in step S200, ECU20 determines whether the difference between the first OCV and the OCV (third OCV) obtained in step S160 is greater than the threshold TH2.

[0087] If ECU20 determines that the difference between the first OCV and the second OCV is greater than the threshold TH2 (YES in step S200), ECU20 updates the full charge capacity.

[0088] In this way, by repeatedly performing the process shown in Figure 5, it is possible to obtain the full charge capacity when the difference between the first OCV and the OCV obtained in step S160 is large. <Example of Estimating Full Charge Capacity> Figure 6 shows the OCV and current value of the energy storage device 40 and the open / closed state of the SMR14 at each time point in Embodiment 2. In the graph shown in Figure 6, the vertical axis represents OCV and the horizontal axis represents time. In Figure 6, "ON" indicates that the SMR14 is ON and "OFF" indicates that the SMR14 is OFF.

[0089] At time t1, electric vehicle 1 finished plugging in and charging. Between time t1 and time t2, electric vehicle 1 was stopped with SMR14 in the OFF state.

[0090] At time t2, SMR14 is turned ON. Then, ECU20 acquires the first OCV (step S130).

[0091] Between time t2 and time t3, electric vehicle 1A is running, and the OCV basically decreases as time progresses.

[0092] At time t3, SMR14 is turned OFF. ECU20 acquires the OCV after the first period has elapsed from time t3 (step S160).

[0093] At time t4, when SMR14 is turned ON, ECU20 calculates the full charge capacity (step S180).

[0094] From time t4 to time t5, electric vehicle 1A is running, and at time t5, electric vehicle 1A is stopped and SMR14 is OFF.

[0095] At time t6, SMR14 is turned ON. Then, in step S160, ECU20 acquires the OCV and calculates the full charge capacity.

[0096] At time t7, SMR14 is turned OFF, and at time t8, SMR14 is turned ON. Then, ECU20 acquires the OCV in step S160 and calculates the full charge capacity in step S180.

[0097] Here, the difference between the first OCV and the OCV obtained in step S160 at time t8 is greater than the threshold TH2. Therefore, in step S180, the ECU20 updates the full charge capacity.

[0098] In the example shown in Figure 6, the electric vehicle 1A repeatedly moves and stops, and the ECU 20 repeatedly calculates and updates the full charge capacity.

[0099] At time t13, SMR14 is OFF, and at time t14, SMR14 is ON. Then, plug-in charging is performed between time t14 and time t15.

[0100] Between time t13 and time t14, the ECU20 does not update the first OCV, but instead acquires the OCV in step S160, calculates the full charge capacity in step S180, and updates the full charge capacity.

[0101] Between time t14 and time t15, electric vehicle 1A is being plugged in and charging, and the OCV is increasing.

[0102] During plug-in charging, the SMR14 is ON, and once plug-in charging is complete, the SMR14 turns OFF.

[0103] At time t15, SMR14 is OFF. Therefore, ECU20 determines that plug-in charging has occurred (YES in S210), and then, upon determining that SMR14 is OFF at time t15 (YES in S140), deletes the first OCV (step S220).

[0104] Then, after time t15, when the user presses the IG button 35 and the SMR14 turns ON, the ECU20 sequentially performs each process from step S100. For example, when the SOC is greater than the threshold TH1, a new first OCV is acquired and stored.

[0105] According to the electric vehicle 1A of the above embodiment 2, by using the first OCV when the SOC is high, it becomes easier to secure the difference between the OCV obtained after the acquisition of the first OCV and the OCV obtained after the acquisition of the first OCV. This makes it easier to accurately calculate the full charge capacity.

[0106] Furthermore, after a plug-in charge has been performed, the OCV with the largest difference from the first OCV during the period until the next plug-in charge can be used to calculate the full charge capacity. This makes it easier to calculate the accurate full charge capacity.

[0107] In the second embodiment, the ECU 20 acquires the first OCV after the user presses the IG button 35, which turns the IG button 35 ON and the SMR 14 ON. Thus, the timing for acquiring the first OCV is when the IG_ON state is reached.

[0108] In step S100, for example, it is assumed that plug-in charging is complete at time t15, and then the IG button 35 is pressed by the user.

[0109] Generally, a considerable amount of time is expected to pass between the completion of plug-in charging and the pressing of the IG button 35. During this time, the polarization caused by charging can be resolved, and an accurate first OCV can be obtained.

[0110] In the above embodiment 2, the acquisition of OCV in step S160 occurs after the SMR14 is turned OFF. In particular, the OCV is acquired after the SMR14 is turned OFF and after the first period has elapsed. This allows for the elimination of polarization generated in the energy storage device 40, for example, when the electric vehicle 1A is running, and enables the acquisition of an accurate OCV.

[0111] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0112] 1 Electric vehicle, 10 Drive unit, 11 Motor generator (MG), 12 Drive wheels, 14 SMR, 20 ECU, 21 Processor, 22 Memory, 23 Storage, 40 Energy storage device, 41 Battery pack, 42 ​​Energy storage module, 43 Energy storage cell, 44 Equalization circuit, 45 Monitoring IC, 51 Voltage sensor, 52 Current sensor, 53 Temperature sensor, P1 First period, P2 Second period, P3 Third period.

Claims

1. The power storage device installed in the electric vehicle, A drive unit that generates driving force using electricity supplied from the aforementioned energy storage device, A relay provided between the energy storage device and the drive device, A voltage sensor for measuring the voltage of the aforementioned energy storage device, A current sensor for measuring the charge and discharge current of the aforementioned energy storage device, It includes a control unit, The control unit, The first OCV is obtained when the relay is OFF. After the control unit turns the relay ON at least once, when the relay turns OFF, the second OCV is acquired. Based on the measurement values ​​from the current sensor, the integrated current value of the energy storage device during the period from the acquisition of the first OCV to the acquisition of the second OCV is calculated. An electric vehicle that calculates the full charge capacity of the energy storage device based on the current integrated value, the first OCV, and the second OCV.

2. The electric vehicle according to claim 1, wherein the control unit acquires the second OCV after the relay is turned OFF and after the first period has elapsed.

3. The electric vehicle according to claim 1, wherein the control unit acquires the first OCV again if a second period has elapsed since the acquisition of the first OCV.

4. The electric vehicle according to claim 1, wherein the control unit acquires the first OCV after the electric vehicle has finished plug-in charging.

5. The electric vehicle according to claim 4, wherein the control unit acquires the first OCV after the electric vehicle has finished plugging in and after the third period has elapsed.

6. The current sensor is located outside the energy storage device. The aforementioned energy storage device includes an energy storage module, The control unit, The information of the internal current flowing within the aforementioned energy storage module is stored, The electric vehicle according to claim 1, wherein the full charge capacity of the energy storage device is calculated based on the internal current, the integrated current value, the first OCV, and the second OCV.

7. The power storage device installed in the electric vehicle, A drive unit that generates driving force using electricity supplied from the aforementioned energy storage device, A voltage sensor for measuring the voltage of the aforementioned energy storage device, A current sensor for measuring the charge and discharge current of the aforementioned energy storage device, It includes a control unit, The control unit, The first OCV is obtained when the State of Control (SOC) of the aforementioned energy storage device is high. After acquiring the first OCV and after the electric vehicle has been running, acquire the second OCV of the energy storage device. The integrated current value of the energy storage device during the period from obtaining the first OCV to obtaining the second OCV is calculated. An electric vehicle that calculates the full charge capacity of the energy storage device based on the current integrated value, the first OCV, and the second OCV.

8. When the control unit determines that the difference between the first OCV and the second OCV is smaller than a predetermined value, it acquires the second OCV, and after the electric vehicle has traveled at least once, it acquires the third OCV of the energy storage device. The electric vehicle according to claim 7, wherein if the difference between the first OCV and the third OCV is greater than the predetermined value, the full charge capacity of the energy storage device is calculated based on the integrated current value at the time of acquisition of the first OCV and the time of acquisition of the third OCV, the first OCV, and the third OCV.

9. The system further includes a relay provided between the energy storage device and the drive device, The electric vehicle according to claim 7, wherein the control unit acquires the second OCV after the relay is turned OFF.

10. The system further includes a relay provided between the energy storage device and the drive device, The electric vehicle according to claim 7, wherein the control unit acquires the first OCV after the relay is turned ON.

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