control device

Abstract

The problem of this invention is to suppress the deviation between the SOC at the end of SOC control and the target value (target SOC) in SOC control that raises or lowers the SOC of a battery to a target SOC. The control device is configured to perform SOC control that raises or lowers the SOC, representing the battery's state of charge, to a target SOC. The control device is configured to, before starting SOC control, use the target SOC to obtain the voltage change caused by battery polarization during the execution of SOC control, and further obtain a termination voltage value using the obtained voltage change. The control device is configured to, after starting SOC control, end SOC control when a parameter related to the battery voltage reaches the termination voltage value.

Description

Technical Field

[0001] This invention relates to a control device. Background Technology

[0002] Japanese Patent Application Publication No. 2003-068370 (Patent Document 1) discloses a technique for obtaining the polarization (polarization electromotive force) of a battery based on its past charging and discharging history, and for calculating the state of charge (SOC) of the battery based on the obtained polarization.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2003-068370 Summary of the Invention

[0004] In the aforementioned techniques, the current polarization of the battery is calculated based on past charging and discharging history. However, the technique described in Patent Document 1 does not predict the future polarization of the battery. Therefore, if polarization occurs during battery charging, a deviation may occur between the SOC at the end of charging and the target value.

[0005] The present invention was made to solve the above-mentioned problems. Its purpose is to suppress the deviation between the SOC at the end of SOC control and the target value (target SOC) in SOC control that raises or lowers the SOC of the battery to a target SOC.

[0006] According to one aspect of the present invention, a control device is provided. The control device is configured to perform SOC control, which raises or lowers the State of Charge (SOC), representing the state of charge of a battery, to a target SOC. The control device is configured to, before initiating SOC control, use the target SOC to obtain the voltage change caused by battery polarization during the execution of SOC control, and further obtain a termination voltage value using the obtained voltage change. The control device is configured to, after initiating SOC control, terminate SOC control when a parameter related to the battery voltage reaches the termination voltage value.

[0007] Invention Effects

[0008] According to the present invention, in SOC control that raises or lowers the SOC of the battery to a target SOC, it is possible to suppress the deviation between the SOC at the end of SOC control and the target value (target SOC). Attached Figure Description

[0009] Figure 1 This is a diagram illustrating the configuration of a vehicle according to an embodiment of the present invention.

[0010] Figure 2 This is a flowchart illustrating the control during vehicle parking as described in this embodiment.

[0011] Figure 3 This is a diagram illustrating the method for obtaining the target SOC according to this embodiment.

[0012] Figure 4 This is a flowchart illustrating the control during driving as described in this embodiment.

[0013] Figure 5 It means Figure 2 The flowchart shows a variation of the processing flow. Detailed Implementation

[0014] The embodiments of the present invention will be described in detail with reference to the accompanying drawings. Identical or corresponding parts in the drawings are labeled with the same symbols, and their descriptions are not repeated.

[0015] Figure 1 This diagram illustrates the configuration of the vehicle 1000 according to this embodiment. The vehicle 1000 includes a battery pack 100 comprising one or more batteries. The battery pack 100 is, for example, fixed under the floor of the vehicle 1000. The mounting method of the battery pack 100 is arbitrary. For example, the battery pack 100 may be disposed on the floor of the vehicle 1000.

[0016] The vehicle 1000 also has an electronic control unit (ECU) 500 that controls the charging and discharging of the battery pack 100, and various sensors (position sensor, outside temperature sensor, vehicle speed sensor, odometer, etc., not shown) that monitor the status of the vehicle 1000 in real time. The detection results of various sensors are output to the ECU 500.

[0017] ECU 500 includes a processor 510 and a storage device 520. The storage device 520 is configured to store information. In ECU 500, the processor 510 executes a program stored in the storage device 520, thereby performing various controls. In addition to the program, the storage device 520 also stores various information used in the program. ECU 500 is an example of the "control device" according to the present invention.

[0018] The vehicle 1000 also includes a drive unit 20 for driving the vehicle 1000, a charging port 410, a charger 420, and a human machine interface (HMI) 600.

[0019] The HMI600 includes input devices and a display device. The HMI600 may include a touch panel display. The input devices output signals corresponding to user input to the ECU500. The display device may include an instrument panel and / or a central display.

[0020] The drive unit 20 includes a power control unit (PCU) 21, an electric generator (MG) 22, and an engine 23. The vehicle 1000 is configured to operate using electricity output from the battery pack 100. The vehicle 1000 is, for example, a plug-in hybrid electric vehicle (PHEV). Alternatively, the vehicle 1000 may also be, for example, a battery electric vehicle (BEV) or other electric vehicle (xEV).

[0021] The battery pack 100 includes multiple battery cells 10 (energy storage cells), each functioning as a secondary battery. The multiple battery cells 10 are stacked and constrained along a predetermined direction, thereby forming a battery stack. The battery stack is a modular energy storage module comprising multiple electrically connected battery cells 10. For example, all battery cells 10 included in the battery stack are constrained by a pair of end plates (constraint plates). In this embodiment, liquid lithium-ion batteries are used as battery cells 10. However, the battery cells 10 are not limited to lithium-ion batteries; for example, they can also be other secondary batteries such as nickel-metal hydride batteries or sodium-ion batteries. The type of secondary battery is not limited to liquid secondary batteries; all-solid-state secondary batteries can also be used.

[0022] The battery pack 100 includes a current sensor Sa, multiple voltage sensors Sb for each battery cell 10, and multiple temperature sensors Sc for each battery cell 10. The detection results from each sensor are output to an ECU 500. The ECU 500, together with these sensors, functions as a Battery Management System (BMS). In this embodiment, all cells 10 included in the battery pack 100 are connected in series, and the same current flows through all battery cells 10. Therefore, one current sensor Sa is shared by all battery cells 10. However, this is not a limitation; the battery pack 100 may also include multiple battery cells connected in parallel. A current sensor may also be provided for each battery cell.

[0023] Figure 1 The vehicle 1000 shown is configured to operate in one driving mode selected from multiple driving modes. For example, the vehicle 1000 is configured to operate in a first driving mode driven only by the MG22 (motor), a second driving mode driven by both the MG22 and the engine 23, and a third driving mode driven only by the engine 23. The ECU 500 can switch between the first to third driving modes according to the condition of the vehicle 1000.

[0024] Furthermore, the vehicle 1000 is configured to perform external charging of the battery pack 100 (charging of the onboard battery based on power supplied from outside the vehicle) while the vehicle is parked. The charging port 410 is configured to connect to an external power supply device (see below). Figure 3 The charging cable is connected. The charger 420 is an on-board charger that performs AC / DC conversion. The ECU 500 controls the charger 420 during external charging. The charger 420 converts AC power to DC power according to instructions from the ECU 500 and outputs the DC power to the battery pack 100. Thus, the individual batteries included in the battery pack 100 are charged.

[0025] PCU21 includes, for example, an inverter. MG22 functions as a drive motor, rotating the drive wheels 24 of vehicle 1000. MG22 uses electricity output from the batteries in battery pack 100 to drive vehicle 1000. Specifically, PCU21 uses electricity supplied from battery pack 100 to drive MG22. Thus, MG22 enters a powered operating state. In the powered operating state, MG22 converts electricity into torque. The torque is transmitted to drive wheels 24. Furthermore, when vehicle 1000 decelerates, MG22 enters a regenerative state, using the regenerated electricity generated to charge the batteries included in battery pack 100.

[0026] Engine 23 functions as an internal combustion engine, using the energy from the combustion of fuel to drive vehicle 1000. Specifically, engine 23 generates power using the energy from the combustion of fuel supplied from a fuel tank (not shown). The generated power is transmitted to drive wheels 24. Exhaust pipe 23a is connected to engine 23, discharging exhaust from engine 23 to the outside of the vehicle.

[0027] The vehicle 1000 also includes a system main relay (SMR) 100b. The SMR 100b is, for example, an electromagnetic mechanical relay. The SMR 100b is located between the battery pack 100 and the drive unit 20 and the charger 420. The SMR 100b remains connected while the vehicle 1000 is operating in the first or second driving mode.

[0028] Figure 2 This is a flowchart illustrating the control of a vehicle during parking based on ECU500. Figure 2 The processing flow F1 shown is repeatedly executed by ECU500 when vehicle 1000 is parked. "S" in the flowchart represents a step.

[0029] In processing flow F1, ECU 500 determines in S11 whether the prescribed charging start condition is met. The charging start condition is the condition for starting external charging. The charging start condition can be met when the charging cable of the power supply equipment is connected to the charging port 410. If a timed charging is scheduled with ECU 500, the charging start condition can be met when the set start time arrives. If the charging start condition is not met ("No" in S11), ECU 500 measures the vehicle parking time (the elapsed time since the vehicle 1000 entered the parking state) in S12 and saves it in storage device 520. Next, in S13, ECU 500 saves the detection value of current sensor Sa, the ambient temperature of current sensor Sa, and the current time in relation to each other in storage device 520. The ambient temperature of current sensor Sa can be detected by multiple temperature sensors Sc installed in battery pack 100, for example, it can be the average or median of multiple temperature data detected by these temperature sensors Sc.

[0030] The processes described in S12 and S13 are performed during vehicle parking. Specifically, the period during which "No" is determined in S11 is a period that is neither during driving nor during power transmission, i.e., the period during which the vehicle is parked. Power transmission in vehicle 1000 is the transmission of power from one of the external devices and the battery pack 100 (vehicle battery) to the other. External charging is an example of power transmission.

[0031] When the charging start condition is met ("Yes" in S11), ECU500 calculates the first polarization in S14. The first polarization represents the voltage change of battery cell 10 caused by the polarization at the start of external charging.

[0032] Specifically, in battery cell 10, the chemical reactions of the electrode active materials during charging and discharging readily occur on the electrode surface, while reactions occurring inside the electrode require time. In battery cell 10 where an imbalance of charge (polarization) occurs between the electrode surface and the electrode interior, a voltage change (polarization electromotive force) is generated in battery cell 10 due to polarization. The greater the polarization, the greater the polarization electromotive force. In S14, ECU 500 uses, for example, the total charge and discharge amounts accumulated during the immediately preceding driving period (see below). Figure 4 The first polarization is calculated based on the vehicle's parking time before external charging begins and the temperature of the battery cell 10, which are obtained in S12. The first polarization is obtained for each battery cell 10. In this embodiment, the total charge is represented as a positive value, and the total discharge is represented as a negative value. Furthermore, the first polarization represents the voltage change to the charging side as a positive value and the voltage change to the discharging side as a negative value.

[0033] The total charge and total discharge are respectively described in the processing flow F2 (described later). Figure 4 The data is obtained from the storage device 520 and stored separately for each driving period. A driving period refers to the time during which the vehicle 1000 is not parked, including not only the time the vehicle 1000 is in motion but also the time during which the vehicle 1000 is temporarily parked. The driving period ends when the vehicle 1000 becomes parked. During the driving period before the start of processing flow F1, the greater the difference between the total charge (absolute value) and the total discharge (absolute value), the more likely the first polarization (absolute value) will increase. Specifically, if the total charge is greater than the total discharge, polarization towards the charging side is more likely to occur. Conversely, if the total discharge is greater than the total charge, polarization towards the discharging side is more likely to occur.

[0034] If battery cell 10 is not charged or discharged, the polarization of battery cell 10 tends to decrease over time. During vehicle parking, SMR 100b remains disconnected, and battery cell 10 is not charged or discharged, resulting in zero current (0A) for each battery cell 10. Therefore, the longer the vehicle is parked before external charging begins, as measured in S12, the smaller the first polarization (absolute value) tends to be. Furthermore, the lower the temperature of battery cell 10, the slower the rate of polarization elimination during vehicle parking tends to be.

[0035] In S14, the processor 510 reads from the storage device 520 the recorded information related to the charging and discharging of the battery cell 10 and the vehicle parking time measured in S12 before the start of external charging. In this embodiment, the historical record information related to the charging and discharging of the battery cell 10 is taken from the immediately preceding driving period (see below). Figure 4 The ECU 500 calculates the sum of the total charge and discharge amounts accumulated in the battery cell 10. The total charge (positive) and total discharge (negative) amounts are calculated. If the total discharge (absolute value) is greater than the total charge (absolute value), the sum of the total charge and discharge amounts becomes negative. Furthermore, the ECU 500 obtains the temperature of the battery cell 10 via the temperature sensor Sc. The storage device 520 pre-stores first polarization information (e.g., a formula) representing the relationship between the sum of the total charge and discharge amounts related to the battery cell 10, vehicle parking time, battery cell temperature, and a first polarization. The ECU 500 can use this first polarization information to obtain the first polarization.

[0036] Furthermore, the method for obtaining the first polarization is not limited to the above and can be arbitrary. For example, the ECU500 can use a pre-trained model to calculate the first polarization. The pre-trained model can be generated through machine learning (AI). The pre-trained model can be trained to output the first polarization when given data representing the voltage shift of the battery cell 10 during vehicle placement and the temperature of the battery cell 10.

[0037] In subsequent step S15, ECU 500 uses the data related to current sensor Sa accumulated during vehicle placement in S13 to obtain temperature characteristic information of current sensor Sa (hereinafter referred to as "current sensor information"). Current sensor information represents the relationship between the offset value of current sensor Sa (the output value when no current flows) and the ambient temperature of current sensor Sa. The offset value of current sensor Sa can vary depending on the ambient temperature. ECU 500 can obtain a formula equivalent to the aforementioned current sensor information from the data related to current sensor Sa accumulated in S13 using the least squares method. ECU 500 performs offset correction of current sensor Sa based on the obtained current sensor information (specifically, correction of detection error caused by the offset value). The current sensor information obtained in S15 is stored in storage device 520. If current sensor information already exists in storage device 520, the current sensor information is updated through the processing in S15.

[0038] Next, in S16, ECU500 uses the voltage of the battery cell 10 in its current-free state and the first polarization to obtain the SOC (hereinafter referred to as "initial SOC") of the battery cell 10. State of charge (SOC) represents the state of charge (e.g., charge rate). The charge rate is, for example, the ratio of the current charge capacity to the charge capacity in a fully charged state, expressed as 0 to 100%. The initial SOC corresponds to the SOC of the battery cell 10 at the start of external charging.

[0039] In this embodiment, the ECU 500 acquires the voltage of the battery cell 10 (hereinafter referred to as "VB1") via the voltage sensor Sb when no current flows through the battery cell 10. VB1 is equivalent to the open circuit voltage (OCV). OCV represents the voltage of the battery cell 10 when no current flows through the battery cell 10. Next, the ECU 500 acquires the first battery voltage (VB1 corrected by the first polarization) by eliminating the influence (voltage change) caused by the first polarization from VB1. The first battery voltage can be the value obtained by subtracting the first polarization from VB1. The storage device 520 pre-stores SOC-OCV information representing the relationship between OCV and SOC related to the battery cell 10 (e.g., Figure 2(See diagram L1 in the figure). SOC-OCV information, for example, defines a relationship where a higher OCV corresponds to a higher SOC. The first battery voltage is equivalent to the OCV of battery cell 10 at the start of external charging. ECU 500 can use the aforementioned SOC-OCV information to obtain the initial SOC (the SOC corresponding to the corrected OCV) based on the first battery voltage (the corrected OCV). The initial SOC is obtained for each battery cell 10.

[0040] In the subsequent S17, ECU 500 acquires the target SOC for external charging. External charging, which begins in S21 (described later), is completed when the SOC of battery cell 10 rises to the target SOC. Processor 510 can read the target SOC, pre-set by the user, from storage device 520. The target SOC can be a fixed value (e.g., the SOC value representing a full charge). Alternatively, ECU 500 can request the target SOC from the user.

[0041] Figure 3 This diagram illustrates an example of a method for acquiring the target SOC. For instance, after the charging cable of the power supply equipment is connected to the charging port 410 of the vehicle 1000, in Figure 2 In the S17, the touch panel display included in the HMI600 shows... Figure 3 Image Sc1 is shown. The touch panel display can be located on an external surface of the vehicle body that can be operated from outside the vehicle (e.g., near the charging port 410). Image Sc1 includes an input section M that accepts numerical input from the user. The value that can be input to the input section M is higher than the initial SOC but less than 100%. Image Sc1 displays a message prompting the user to input the target SOC and the initial SOC. The ECU 500 sets the value input by the user into the input section M as the target SOC.

[0042] If in Figure 2 In S17, the target SOC is obtained. Then, in S18, the ECU 500 obtains a second polarization based on the target SOC. The second polarization represents the voltage change caused by the polarization of the battery cell 10 during external charging. The storage device 520 pre-stores second polarization information (e.g., as shown in the figure) representing the relationship between the target SOC and the second polarization associated with the battery cell 10. The second polarization information, for example, defines a relationship that the higher the target SOC, the larger the second polarization. The ECU 500 can use such second polarization information to predict the second polarization. Furthermore, the ECU 500 can correct the second polarization based on the temperature of the battery cell 10 (e.g., the average temperature of all battery cells 10). The target SOC and the second polarization are common to all battery cells 10.

[0043] Next, in S19, ECU500 uses the target SOC, the first polarization, and the second polarization to obtain the second battery voltage. Hereinafter, the second battery voltage will be labeled "VB2". VB2 represents the OCV of battery cell 10 at the end of external charging. VB2 is higher than the first battery voltage.

[0044] Specifically, ECU500 uses the aforementioned SOC-OCV information (e.g., Figure 2 The ECU 500 obtains the OCV corresponding to the target SOC (as shown in the diagram with line L1). Then, the ECU 500 obtains VB2 by excluding the effects (voltage changes) caused by the first and second polarizations from the obtained OCV. VB2 can be the value obtained by subtracting the sum of the first polarization (voltage change caused by polarization at the start of external charging) and the second polarization (voltage change caused by polarization during external charging) from the OCV corresponding to the target SOC. VB2 is obtained for each battery cell 10. The second polarization information and VB2 are respectively examples of the "polarization information" and "termination voltage value" involved in this invention.

[0045] If the process in S19 is executed, the ECU 500 sets the SMR 100b to the connected state and begins external charging control in S21. In S21, while AC power is being supplied to the charger 420 from an external power source via the charging port 410, the ECU 500 controls the charger 420. As a result, power supplied from outside the vehicle is input to each battery cell 10, and the state of charge (SOC) of each cell 10 increases. In S21, the ECU 500 performs SOC control to raise the SOC of at least one battery cell 10 to a target SOC.

[0046] In subsequent step S22, ECU 500 accumulates the charging power detected by current sensor Sa and voltage sensor Sb. At this time, ECU 500 obtains the corrected detection value of current sensor Sa based on current sensor information (S15) and the current ambient temperature of current sensor Sa. Through processing in S22, the total charging amount in external charging (the charging amount input to battery cell 10) is calculated. Then, ECU 500 stores the calculated total charging amount in external charging in storage device 520. Storage device 520 distinguishes between the total charging amount in external charging and the total charging amount during driving.

[0047] In subsequent step S23, ECU 500 determines whether the specified termination condition is met. For example, if the user requests ECU 500 to terminate external charging, the termination condition is met. If the termination condition is determined not to be met ("No" in S23), ECU 500 determines in S24 whether the OCV of at least one battery cell 10 is above VB2. In S24, since battery cell 10 is charging, a voltage drop caused by current occurs. ECU 500 obtains the OCV of battery cell 10 by excluding the voltage drop caused by battery current from the voltage of battery cell 10 (inter-terminal voltage of battery cell 10) detected by voltage sensor Sb. Specifically, the OCV of battery cell 10 can be obtained by subtracting the product of the current and internal resistance of battery cell 10 from the detected value of voltage sensor Sb. The current of battery cell 10 is detected by current sensor Sa. At this time, ECU 500 obtains the detected value of current sensor Sa after correction of offset based on current sensor information (S15) and the current ambient temperature of current sensor Sa. The internal resistance of battery cell 10 is pre-stored in storage device 520. ECU 500 can use the temperature of battery cell 10 detected by temperature sensor Sc to correct the internal resistance of battery cell 10. Through external charging (S21), the OCV of each battery cell 10 increases.

[0048] If the OCV of any battery cell 10 does not reach VB2 ("No" in S24), the process returns to S21. During the period when the termination condition is not met and the OCV of any battery cell 10 does not reach VB2 ("No" in both S23 and S24), S21 to S24 are repeated. Thus, the external charging of the battery pack 100 is continuously performed (S21), and the total charge amount in the external charging is updated (S22).

[0049] If the termination condition for external charging is met ("Yes" in S23), the ECU 500 terminates external charging by requesting the power supply to stop supplying power. In this case, after the ECU 500 sets SMR100b to the off state, process flow F1 ends, and the process returns to the initial step (S11). On the other hand, if the OCV of at least one battery cell 10 becomes VB2 or higher through external charging ("Yes" in S24), the ECU 500 determines that external charging is complete and requests the power supply to stop supplying power. In this case, after the ECU 500 sets SMR100b to the off state, the process proceeds to S31.

[0050] In S31, ECU500 calculates the capacity C (battery capacity) of battery cell 10 according to the formula shown below. Capacity C is equivalent to the amount of electricity stored in battery cell 10 when fully charged.

[0051] C = 100 × dST / |SOC1 - SOC2| In the above formula, "SOC1" represents the initial SOC, and "SOC2" represents the target SOC. |SOC1 - SOC2| is equivalent to the difference (absolute value) between the initial SOC and the target SOC. "dST" represents the total charge amount during the period from the start of external charging to the end (hereinafter referred to as the "charging period"). During the charging period, the total charge amount during the charging period is stored in the storage device 520 by repeatedly performing the process S22. The ECU 500 obtains the capacity C for each battery cell 10 according to the above formula and stores the capacity C of each battery cell 10 in the storage device 520. According to this method, the capacity of each battery cell 10 can be detected with high accuracy.

[0052] In subsequent S32, ECU 500 uses the total charge / discharge amount of battery cell 10 accumulated from its initial state (e.g., at the time of manufacture) to the present and the capacity of battery cell 10 obtained in S31 to calculate the expansion amount of battery cell 10. The total charge / discharge amount is, for example, the sum of the total charge amount (absolute value) during all driving periods, the total discharge amount (absolute value) during all driving periods, and the total charge amount (absolute value) during all charging periods. For example, storage device 520 pre-stores expansion information (e.g., figure) representing the relationship between total charge / discharge amount, capacity, and expansion amount related to battery cell 10. Battery cell 10 tends to expand with increasing total charge / discharge amount. The larger the capacity of battery cell 10, the greater the tendency for its expansion amount to increase. Moreover, the greater the expansion amount of battery cell 10, the greater the constraint load on battery cell 10. The expansion information is defined based on the characteristics of the battery cell 10, with the following relationships: the greater the total charge / discharge capacity of the battery cell 10, the greater the expansion of the battery cell 10; and the greater the capacity of the battery cell 10, the greater the expansion of the battery cell 10. The ECU 500 can use this expansion information to obtain the expansion amount of the battery cell 10. Furthermore, the ECU 500 can adjust the expansion amount based on the temperature of the battery cell 10. The expansion amount is obtained for each battery cell 10 and stored in the storage device 520.

[0053] In subsequent S33, ECU 500 sets the lower and upper limits of the State of Charge (SOC) of battery cell 10 based on the expansion amount of battery cell 10. During driving, ECU 500 controls the SOC of battery cell 10 within the SOC range from the lower limit to the upper limit (hereinafter referred to as the "practical SOC region"). In S33, the larger the expansion amount of battery cell 10 calculated by ECU 500 in S32, the narrower the practical SOC region. ECU 500 may also adjust the SOC range accordingly: the larger the expansion amount of battery cell 10, the lower the upper limit of SOC. ECU 500 may also adjust the SOC range accordingly: the larger the expansion amount of battery cell 10, the higher the lower limit of SOC. The practical SOC region corresponds to the amount of usable energy within the capacity C (battery capacity) of battery cell 10 obtained in S31. The narrower the practical SOC region, the less usable energy. On the other hand, a narrower practical SOC region further suppresses the expansion of battery cell 10. If the processing in S33 is executed, then the processing flow F1 ends and the processing returns to S11.

[0054] According to the above method, the expansion amount of each battery cell 10 can be detected with high precision. Furthermore, by controlling based on the detected expansion amount, the expansion of each battery cell 10 can be appropriately suppressed.

[0055] Figure 4 This is a flowchart representing the controls performed by the ECU500 during driving. Figure 4 The processing flow F2 shown is repeatedly executed by ECU500 during the driving of vehicle 1000.

[0056] In processing step F2, ECU 500 determines in step S51 whether battery pack 100 (including battery stack) is charging. Battery pack 100 can be charged by regenerative braking during driving.

[0057] When the battery pack 100 is charging ("Yes" in S51), the ECU 500 controls the input power to the battery pack 100 in S52 to ensure that the SOC of any battery cell 10 does not exceed the upper limit of SOC. The upper limit of SOC is, for example, at... Figure 2The settings are configured in S33. If the State of Charge (SOC) of any battery cell 10 is likely to exceed the SOC upper limit, the ECU 500 performs control to suppress the input power to the battery pack 100. This suppresses the rise in the SOC of each battery cell 10. Specifically, the ECU 500 can control the PCU 21 to suppress the input power to the battery pack 100. Furthermore, when the vehicle 1000 is driving in the third driving mode, the ECU 500 can switch to the first or second driving mode. If the SOC of any battery cell 10 reaches the SOC upper limit, the ECU 500 can set the SMR 100b to the off state, prohibiting power input to the battery pack 100. At this time, if the vehicle 1000 is driving in the first or second driving mode, the ECU 500 can switch to the third driving mode, allowing the engine 23 to continue driving the vehicle 1000.

[0058] In the subsequent S53, ECU500 and Figure 2 Similarly, S22 accumulates the charging power. Thus, the total charging amount during driving is calculated. Then, the ECU 500 stores the calculated total charging amount in the storage device 520. During the continuous charging of the battery pack 100 during driving, processes S52 and S53 are repeatedly executed. In S52, the aforementioned battery input suppression control is performed, and the total charging amount during driving is updated through the processing in S53.

[0059] If the battery pack 100 is not charging ("No" in S51), the process proceeds to S54. In S54, the ECU 500 determines whether the battery pack 100 (including the battery stack) is discharging. If the battery pack 100 is discharging ("Yes" in S54), the ECU 500 controls the power output from the battery pack 100 in S55 to ensure that the SOC of any battery cell 10 does not fall below the lower SOC limit. The lower SOC limit is, for example, at... Figure 2 The settings are configured in S33. If the State of Charge (SOC) of any battery cell 10 is likely to fall below the lower SOC limit, the ECU 500 performs control to suppress the output power from the battery pack 100. This suppresses the decrease in the SOC of each battery cell 10. Specifically, the ECU 500 can control the PCU 21 to suppress the output power from the battery pack 100. Furthermore, when the vehicle 1000 is traveling in the first driving mode, the ECU 500 can switch to the second or third driving mode. If the SOC of any battery cell 10 reaches the lower SOC limit, the ECU 500 can set the SMR 100b to the off state, prohibiting power output from the battery pack 100. At this time, if the vehicle 1000 is traveling in the first or second driving mode, the ECU 500 can switch to the third driving mode, allowing the engine 23 to continue driving the vehicle 1000.

[0060] In the subsequent S56, ECU500 accumulates the discharge power detected by current sensor Sa and voltage sensor Sb. At this time, ECU500 based on... Figure 2 The latest current sensor information and the ambient temperature of the current sensor Sa are obtained in S15 to obtain the corrected value of the current sensor Sa. Through processing in S56, the total discharge amount during driving (the discharge amount output from battery cell 10) is calculated. The ECU 500 stores the calculated total discharge amount in storage device 520. During the continuous discharge of battery pack 100 during driving, processes S55 and S56 are repeatedly executed. The aforementioned battery output suppression control is performed in S55, and the total discharge amount during driving is updated through processing in S56.

[0061] If the process in S56 is executed, the process proceeds to S57. Furthermore, if the process in S53 has been executed, and the subsequent S54 is deemed "no," the process proceeds to S57. In S57, the ECU 500 displays the capacity and expansion amount of the battery pack 100 on a display device (e.g., an instrument panel) included in the HMI 600. The capacity of the battery pack 100 is equivalent to the total capacity C of all battery cells 10 included in the battery pack 100. The ECU 500 is used in… Figure 2 The capacity of the battery pack 100 is calculated using the latest data (capacity C of each battery cell 10) calculated in S31. The capacity of the battery pack 100 can be expressed as battery capacity (kWh) or capacity retention rate (%). The expansion amount of the battery pack 100 is equivalent to the sum of the expansion amounts of all battery cells 10 included in the battery pack 100. ECU500 uses... Figure 2 The expansion amount of the battery pack 100 is calculated using the latest data (expansion amount of each battery cell 10) calculated in S32. The expansion amount of the battery pack 100 can be represented by a constraint load. The ECU 500 can display the capacity and expansion amount indicators (e.g., the lower limit of capacity and the upper limit of expansion amount) on the display device. These indicators serve as indicators of the replacement period of the battery pack 100 and are displayed together with the capacity and expansion amount of the battery pack 100. If the processing in S57 is executed, the processing returns to the initial step (S51).

[0062] As explained above, the control device (ECU500) involved in this embodiment is configured to perform SOC control that raises the SOC of the battery (battery cell 10) to a target SOC. Before starting SOC control, the control device uses the target SOC to obtain the voltage change caused by battery polarization that occurs during the execution of SOC control. Figure 2 (S18), and use the obtained voltage change to further obtain the termination voltage value (VB2) ( Figure 2(S19). After initiating SOC control, the control device terminates SOC control when the voltage-related parameter (OCV) of the battery reaches the termination voltage value. Figure 2 (S24). The aforementioned control device (ECU500) predicts the second polarization of the battery (voltage change caused by battery polarization during the execution of SOC control) that will occur in the future based on the target SOC. Therefore, the predicted second polarization can be used to suppress the deviation between the SOC at the end of SOC control and the target value (target SOC).

[0063] In the above embodiment, an example is shown of suppressing the deviation between the SOC at the end of SOC control and the target SOC in SOC control (S21) that raises the SOC of the battery (battery cell 10) to the target SOC. However, in SOC control that lowers the SOC of the battery (battery cell 10) to the target SOC, it is also possible to suppress the deviation between the SOC at the end of SOC control and the target SOC. For example, the vehicle 1000 may be configured to perform external power supply (power supply that outputs power from the vehicle battery to the outside of the vehicle) while the vehicle is parked. Then, the ECU 500 can execute... Figure 5 The processing flow shown is F3 instead. Figure 2 The processing flow shown is F1.

[0064] Figure 5 It means Figure 2 The flowchart shows a modified example of the processing flow. Figure 5 In the processing flow F3 shown, the process flow F1 described above is similar to that of the aforementioned processing flow F1. Figure 2 Similarly, processes S11 to S19 are executed. In S17, ECU 500 acquires a target SOC lower than the initial SOC. ECU 500 may also request input from the user for a target SOC lower than the initial SOC. In S19, VB2 is acquired and found to be lower than the voltage of the first battery (S16). If process S19 is executed, the process proceeds to S21A. In S21A, ECU 500 performs external power supply control. In S21A, ECU 500 performs SOC control to reduce the SOC of at least one battery cell 10 to the target SOC. Vehicle 1000 can be supplied with power from an external power source, such as an external electrical system or a stationary energy storage device. In S22A, ECU 500 accumulates the discharge power detected by current sensor Sa and voltage sensor Sb. In S23A, ECU 500 determines whether a predetermined termination condition is met. For example, if the user requests ECU 500 to terminate the external power supply, the termination condition is met. If the termination condition is not met ("No" in S23A), the ECU500 determines in S24A whether the OCV of at least one battery cell 10 is below VB2.

[0065] In S24A, since battery cell 10 is discharging, a voltage drop caused by current occurs. ECU 500 obtains the OCV of battery cell 10 by excluding the portion of the voltage drop caused by battery current from the voltage of battery cell 10 (the inter-terminal voltage of battery cell 10) detected by voltage sensor Sb. In at least one of S22A and S24A, ECU 500 can obtain the detected value of current sensor Sa after correction of offset based on current sensor information (S15) and the ambient temperature of current sensor Sa. With external power supply (S21A), the OCV of each battery cell 10 decreases. If the OCV of at least one battery cell 10 reaches VB2 when powered by external power supply ("Yes" in S24A), ECU 500 determines that external power supply is complete and ends external power supply. In this case, after ECU 500 sets SMR100b to the off state, it proceeds with the aforementioned processing flow F1 ( Figure 2 Similarly, the processes S31 to S33 are executed. In S31, the total discharge amount during the period from the start of external power supply to the end is substituted into "dST" in the aforementioned formula.

[0066] According to the aforementioned processing flow F3, in the SOC control that reduces the SOC of the battery (battery cell 10) to the target SOC, the deviation between the SOC at the end of the SOC control and the target SOC can be suppressed. The ECU 500 can be configured to execute both processing flows F1 and F3. The ECU 500 can select either processing flow F1 or F3 based on the condition of the vehicle 1000 or a request from the user, and execute the selected processing flow.

[0067] Figure 2 , Figure 4 , Figure 5 The illustrated processing flow can be modified as appropriate. For example, the order of processes can be changed depending on the purpose, or unnecessary steps can be omitted. Furthermore, the content of any process can be modified. For example, in a method using a current sensor that is less prone to detection errors caused by offset values, in... Figure 2 or Figure 5 In this process, the processing related to the offset correction of the current sensor (S13, S15) can be omitted.

[0068] Figure 1 The configuration of the vehicle shown can be modified as appropriate. The purpose of the control device is arbitrary. The control device can also be used with a stationary battery instead of an onboard battery.

[0069] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is set forth in the claims, not in the description of the above embodiments, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0070] Symbol Explanation

[0071] 10 - Battery cell, 100 - Battery pack, 500 - ECU, 520 - Storage device, 1000 - Vehicle, Sa - Current sensor, Sb - Voltage sensor.

Claims

1. A control device configured to perform SOC control, which causes the State of Charge (SOC) of a battery to rise or fall to a target SOC, characterized in that... The control device is configured as follows: Before initiating the SOC control, the voltage change caused by the polarization of the battery during the execution of the SOC control is obtained using the target SOC, and the obtained voltage change is further used to obtain the termination voltage value. After the SOC control is initiated, the SOC control is terminated when the parameters related to the battery voltage reach the termination voltage value.

2. The control device according to claim 1, characterized in that, The control device is configured as follows: When the battery is not being charged or discharged, the data collected includes the current sensor readings that detect the battery current and data related to the ambient temperature. The accumulated data is used to obtain temperature characteristic information representing the relationship between the offset value of the current sensor and the ambient temperature. During the execution of the SOC control, the open-circuit voltage of the battery is obtained as the parameter related to the battery voltage, using the voltage of the battery detected by the voltage sensor and the detection value of the current sensor after the offset is corrected by the temperature characteristic information.

3. The control device according to claim 1 or 2, characterized in that, The control device includes a storage device that stores SOC-OCV information representing the relationship between the battery's SOC and open-circuit voltage. The control device is configured as follows: Using historical charging and discharging information related to the battery, a first polarization amount is obtained, representing the voltage change caused by the polarization of the battery at the start of the SOC control. The termination voltage value is obtained using the first polarization, the second polarization representing the voltage change caused by the polarization of the battery during the execution of the SOC control, the SOC-OCV information, and the target SOC.

4. The control device according to claim 3, characterized in that, The control device is configured as follows: Using the open-circuit voltage of the battery, the first polarization, and the SOC-OCV information, the initial SOC of the battery at the start of the SOC control is obtained. During the execution of the SOC control, the charging power or discharging power of the battery is accumulated. After the SOC control ends, the battery capacity is calculated using the accumulated charge or discharge capacity of the battery during the execution of the SOC control, the initial SOC, and the target SOC.

5. The control device according to claim 4, characterized in that, The storage device also stores polarization information representing the relationship between the target SOC and the second polarization quantity. The control device is configured as follows: Based on user input, the target SOC is obtained. The second polarization quantity is obtained using the polarization information and the target SOC input by the user.

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