Battery control device

Abstract

The power supply system includes a first current sensor (22) with a first range defined as its current detection range and a second current sensor (23) with a second range wider than the first range defined as its current detection range, serving as a current sensor for detecting the current flowing through the battery (21). The battery control device (70) includes: an anomaly determination unit that determines whether the first current sensor is malfunctioning; a first charging control unit that, when it is determined that the first current sensor is not malfunctioning, performs a charging completion determination based on the detected current of the first current sensor; and a second charging control unit that, when it is determined that the first current sensor is malfunctioning, uses the second current sensor instead of the first current sensor and performs the charging completion determination based on the detected current of the second current sensor. Furthermore, the determination criteria for performing the charging completion determination in the first charging control unit and the second charging control unit are different.

Description

[0001] Citation of relevant applications

[0002] This application is based on Japanese Patent Application No. 2020-119244, filed on July 10, 2020, the contents of which are incorporated herein by reference. Technical Field

[0003] The disclosure in this specification relates to a battery control device. Background Technology

[0004] In power systems with batteries, a known technology for charging the battery using an external charging device is, for example, the vehicle charging control device described in Patent Document 1. In this charging control device, the current detection unit is configured to have a current sensor that detects the current input to the battery, and outputs a first detection value with a first resolution and a second detection value with a second resolution higher than the first resolution. Furthermore, when the charging power calculated using the first detection value exceeds a predetermined limit, the charging control device controls the charger to reduce the charging power, and controls the charger to bring the battery to a predetermined fully charged state based on the charging power calculated using the second detection value.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-50175 Summary of the Invention

[0008] Furthermore, in power systems, it is believed that if the current sensor malfunctions, the current input to the battery cannot be detected, making it difficult to properly charge the battery. For example, Patent Document 1 lacks any description of how to handle malfunctions in the current sensor used for charging control, suggesting room for improvement.

[0009] This disclosure is made in view of the above circumstances, and its main objective is to provide a battery control device that can correctly implement charging control even when the current sensor for charging is malfunctioning.

[0010] Method 1 is a battery control device.

[0011] The aforementioned battery control device is applicable to a power supply system including a first current sensor and a second current sensor as current sensors for detecting the current flowing through the battery. When the battery is charged by a charging device, charging completion is determined based on the detected current of the first current sensor. The first current sensor has a first range defined as its current detection range, and the second current sensor has a second range wider than the first range defined as its current detection range. The battery control device includes:

[0012] Anomaly determination unit determines whether the first current sensor has malfunctioned.

[0013] The first charging control unit, when determining that the first current sensor is not malfunctioning, performs a charging completion determination based on the detected current of the first current sensor when charging is initiated by the charging device; and

[0014] The second charging control unit, when determining that the first current sensor has malfunctioned, uses a second current sensor instead of the first current sensor, and performs a charging completion determination based on the detected current of the second current sensor when charging is performed by the charging device.

[0015] The criteria for determining the completion of charging are different in the first charging control unit and the second charging control unit.

[0016] In the event of a malfunction in the first current sensor, a second current sensor is used instead of the first current sensor, and the charging completion determination is performed based on the current detected by the second current sensor. Furthermore, the criteria for determining charging completion differ between the charging control based on the current detected by the first current sensor and the charging control based on the current detected by the second current sensor.

[0017] Because the detection ranges of the first and second current sensors are different, their detection resolutions, i.e., the magnitudes of their errors, differ. In this situation, when the second current sensor is used instead of the first current sensor to determine battery charging completion, the accuracy of the determination may decrease due to the difference in the detection ranges (error magnitudes) of the current sensors. However, since the criteria for determining charging completion differ with the change of current sensors, the decrease in accuracy can be suppressed. As a result, charging control can be accurately implemented even when the charging current sensor malfunctions.

[0018] Method 2 is based on Method 1, where the first charging control unit determines that charging is complete when the detected current of the first current sensor is below a first threshold, and the second charging control unit determines that charging is complete when the detected current of the second current sensor is below a second threshold that is greater than the first threshold.

[0019] When the current detected by the second current sensor is used to determine charging completion, overcharging may occur because the detection resolution of the second current sensor is lower than that of the first current sensor, i.e., the error is larger. To address this, by using a second threshold, which is larger than the first threshold used as the reference value for determining charging completion when using the first current sensor, as the reference value for determining charging completion, it is possible to determine that charging is complete and stop charging earlier, thereby suppressing overcharging.

[0020] Method 3 is based on Method 2. When the battery is charged by the charging device, the battery control device performs constant current charging by setting the charging current of the charging device to a constant value to charge the battery. After the constant current charging, the battery is charged by setting the charging voltage of the charging device to a constant value to charge the battery. The second charging control unit sets the target voltage in the constant voltage charging to a lower voltage than when the first charging control unit performs the constant voltage charging.

[0021] When using a second current sensor with lower detection resolution, charging completion determination may be delayed during rapid charging at constant voltage, potentially leading to overcharging. To address this, in the event of a malfunction in the first current sensor, when using the second current sensor instead of the first for charging completion determination, the target voltage during constant voltage charging is set to a lower voltage than when constant voltage charging is performed by the first charging control unit. This effectively suppresses overcharging.

[0022] Method 4 is based on Method 1. When the battery is charged by the charging device, the battery control device performs constant current charging by setting the charging current of the charging device to a constant value to charge the battery. After the constant current charging, the battery control device performs constant voltage charging by setting the charging voltage of the charging device to a constant value to charge the battery. The first charging control unit determines that charging is complete based on the detection current of the first current sensor being below a first threshold. The second charging control unit determines that charging is complete based on either the earlier of the detection current of the second current sensor being below a second threshold that is greater than the first threshold or the start of constant voltage charging and the elapsed time.

[0023] When determining charging completion based on the detected current of the second current sensor, charging is considered complete if either the detected current of the second current sensor is below a second threshold (which is greater than a first threshold) or if constant voltage charging has started and a predetermined time has elapsed earlier. In this case, by determining charging completion early while taking into account that the detection resolution of the second current sensor is lower than that of the first current sensor (i.e., the error is larger), overcharging can be suppressed. Furthermore, if a predetermined time has elapsed since the start of constant voltage charging before the charging completion determination based on the second threshold is established, charging is determined to be complete at the point when that predetermined time has elapsed. Therefore, when using the second current sensor, even if it is assumed that charging completion determination cannot be accurately performed due to errors included in the detected current, the implementation of constant voltage charging can be limited based on the elapsed time since the start of constant voltage charging, thereby suppressing battery overcharging.

[0024] Method 5 is based on Method 1. When the battery is charged by the charging device, the battery control device performs constant current charging by setting the charging current of the charging device to a constant value to charge the battery. After the constant current charging, the battery performs constant voltage charging by setting the charging voltage of the charging device to a constant value to charge the battery. At the same time, as a charging mode, a normal charging mode and a fast charging mode can be selected. The first charging control unit determines that charging is complete when the current detected by the first current sensor is below a first threshold. If the charging mode is the normal charging mode, the second charging control unit determines that charging is complete when the current detected by the second current sensor is below a second threshold that is greater than the first threshold. If the charging mode is the fast charging mode, the second charging control unit determines that charging is complete when the constant current charging is completed.

[0025] When using a second current sensor with lower detection resolution, charging completion determination may be delayed during rapid charging at constant voltage, potentially leading to overcharging. This possibility increases in fast charging mode. To address this, in the event of a malfunction in the first current sensor, if the charging mode is normal, charging is determined to be complete when the detected current from the second current sensor falls below a second threshold (which is greater than a first threshold). If the charging mode is fast charging, charging is determined to be complete based on the completion of constant current charging. This allows the timing of charging completion determination in fast charging mode to be earlier than in normal charging mode, thus suppressing overcharging.

[0026] Method 6 is based on any one of Methods 2 to 5, wherein the battery control device includes a correction unit. When the second charging control unit determines that charging is complete using the second threshold, the correction unit acquires the terminal voltage of the battery after charging is complete and corrects the second threshold based on the terminal voltage.

[0027] Ideally, the magnitude of the error included in the detected current of the second current sensor should be considered when determining the second threshold for comparison with the detected current of the second current sensor. To suppress overcharging, a large margin is desirable. However, on the other hand, if the second threshold is too large, battery charging may be excessively restricted. To address this, the battery terminal voltage is acquired after charging is complete, and the second threshold is adjusted based on this terminal voltage. In this case, based on the battery terminal voltage, it is possible to determine whether the charging is excessive or insufficient relative to the battery's full charge state. Therefore, in addition to suppressing overcharging, undercharging can also be suppressed. Attached Figure Description

[0028] The above-mentioned objects, other objects, features, and advantages of this disclosure will become clearer with reference to the accompanying drawings and the following detailed description. The accompanying drawings are described below.

[0029] Figure 1 This is a structural diagram showing the vehicle's power system.

[0030] Figure 2 This is a timing diagram used to illustrate CC charging and CV charging.

[0031] Figure 3 This is a flowchart illustrating the processing steps of charging control.

[0032] Figure 4 This is a flowchart illustrating the charging control processing steps in the second embodiment.

[0033] Figure 5 This is a flowchart illustrating the charging control processing steps in the third embodiment.

[0034] Figure 6 This is a flowchart illustrating the charging control processing steps in the fourth embodiment.

[0035] Figure 7 This is a flowchart illustrating the correction process for the second threshold in the fifth embodiment.

[0036] Figure 8 This is a flowchart illustrating the setting process of the second threshold in other embodiments.

[0037] Figure 9This is a graph showing the relationship between the degree of battery degradation and the second threshold. Detailed Implementation

[0038] (First Implementation)

[0039] Hereinafter, the embodiment will be described with reference to the accompanying drawings. This embodiment is applicable to electric vehicles having an electric motor as a driving power source. First, by... Figure 1 An overview of the power system for electric vehicles is provided.

[0040] exist Figure 1 In this embodiment, vehicle 10 includes: a main battery 21; an inverter 30 that converts DC power from the main battery 21 into AC power; and an electric motor 40, driven by the AC power output from the inverter 30, serving as an electrical load. When vehicle 10 is in motion, power is supplied from the main battery 21 to the electric motor 40 via the inverter 30 according to the driver's throttle input. The electric motor 40, driven by the power supplied, provides driving power to vehicle 10. The electric motor 40 is a rotating electric machine (electric generator) that, in addition to its driving function, also has a power generation function. For example, when vehicle 10 decelerates, the generated electricity from regenerative braking is supplied to the main battery 21 via the inverter 30. In this case, the electric motor 40 functions as a generator, charging the main battery 21 with the generated electricity. Furthermore, in this embodiment, the main battery 21 is equivalent to a "storage battery".

[0041] The main battery 21 is a rechargeable and dischargeable battery, consisting of a battery pack composed of multiple battery cells connected in series. The main battery 21 is, for example, a lithium-ion battery with an output voltage of approximately 100V. The main battery 21, along with various sensors, is configured as a battery unit 20. The battery unit 20 includes: current sensors 22 and 23, which detect the current input to and output to the main battery 21; a voltage sensor 24, which detects the terminal voltage of the main battery 21; and a temperature sensor 25, which detects the temperature of the main battery 21.

[0042] Additionally, the auxiliary battery 60 is connected to the main battery 21 via a DC-DC converter 50, which acts as a power converter. The auxiliary battery 60 is a battery with a rated voltage lower than that of the main battery 21, such as a lead-acid battery with an output voltage of approximately 12V. The DC-DC converter 50 steps down the high voltage of the main battery 21 to the voltage level of the auxiliary battery 60 and supplies power to the auxiliary battery 60.

[0043] Furthermore, the main battery 21 can be charged using power supplied from an external charging device 100. The external charging device 100 is, for example, a charger installed at a charging station, connected to the vehicle 10 via a charging cable, and can charge the main battery 21 from the external charging device 100. The external charging device 100 is configured to output power at a constant current, at a constant voltage, or at a constant voltage and constant current.

[0044] In addition, the vehicle 10 includes a battery control unit 70 and an electric motor control unit 80, which are mainly microcomputers with CPUs or various types of memory. The battery control unit 70 and the electric motor control unit 80 are connected to each other via a communication network such as CAN and are able to communicate with each other. Furthermore, the battery control unit 70 and the external charging device 100 can communicate with each other via a charging cable used for external charging or via a communication unit such as a wireless LAN.

[0045] The aforementioned control devices 70 and 80 appropriately utilize the detection information obtained from various sensors in the battery cell 20 to implement control related to the charging and discharging of the main battery 21 or the driving of the motor 40. Here, the detection ranges of the current sensors 22 and 23 in the battery cell 20 are different from each other; one current sensor 22 defines its current detection range as a first range, while the other current sensor 23 defines its current detection range as a second range wider than the first range. In this case, the battery control device 70 implements charging control during battery charging by the external charging device 100 based on the current detected by the current sensor 22. Furthermore, the motor control device 80 implements driving control achieved by driving the motor 40 based on the current detected by the current sensor 23. In the following description, the current sensor 22 will be referred to as the first current sensor 22, and the current sensor 23 will be referred to as the second current sensor 23.

[0046] Further explanation is provided for each current sensor 22 and 23. Because the current detection range of the first current sensor 22 is narrower than that of the second current sensor 23, its detection resolution is higher and its error is smaller. Conversely, because the current detection range of the second current sensor 23 is wider than that of the first current sensor 22, its detection resolution is lower and its error is larger.

[0047] When the battery control device 70 performs external charging using the external charging device 100, it charges the main battery 21 using a CC-CV charging method. CC charging is a constant current charging method where the charging current of the external charging device 100 is set to a constant value and the main battery 21 is charged using a constant current method. CV charging is a constant voltage charging method where the charging voltage of the external charging device 100 is set to a constant value and the main battery 21 is charged using a constant voltage method. Figure 2 The CC-CV charging method will be explained. Figure 2 The diagram shows the shift in the terminal voltage of the main battery 21 and the shift in the charging current flowing through the main battery 21 after external charging begins.

[0048] exist Figure 2 During CC charging, from the start of charging until time t11, a constant charging current is maintained. During CC charging, the terminal voltage of the main battery 21 gradually increases over time. During CC charging, it is preferable to determine a predetermined target current in the battery control device 70 and to implement output current control of the external charging device 100 in a manner that makes the actual current flowing through the main battery 21 (the current detected by the first current sensor 22) consistent with the target current.

[0049] Then, at time t11, if the switching condition from CC charging to CV charging is met, the switching from CC charging to CV charging is performed. For example, it is preferable to use the terminal voltage of the main battery 21 as the parameter for charging switching, and to switch from CC charging to CV charging based on the terminal voltage reaching a predetermined voltage Vth. After time t11, the battery control device 70 indicates the target charging voltage to the external charging device 100. Alternatively, the switching from CC charging to CV charging can be performed at a predetermined time point after the start of CC charging.

[0050] After time t11, CV charging with a constant charging voltage is performed. During CV charging, the charging current of the main battery 21 gradually decreases over time. Then, at time t12, if the charging current of the main battery 21 decreases to a predetermined current threshold Ith (cutoff current), charging ends. At this time, the battery control device 70 determines that charging is complete based on the detection current of the first current sensor 22 decreasing to the current threshold Ith.

[0051] During external charging, it is preferable to send the output current detected by the external charging device 100 as output current information to the battery control device 70. For example, the external charging device 100 uses a current detection unit, such as a current sensor included in the external charging device 100, to detect the output current output from the external charging device 100 and sends this current information to the battery control device 70. The battery control device 70 compares the output current information from the external charging device 100 with the current detected by the first current sensor 22 during external charging. If there is a difference between them, it sends a correction instruction to the external charging device 100 for the output current. For example, based on the output current information sent from the external charging device 100, if the output current value is 100 amps and the current detected by the first current sensor 22 is 95 amps, the battery control device 70 instructs the external charging device 100 to increase the output current by 5 amps.

[0052] Furthermore, it is believed that if the first current sensor 22 used in the charging control during external charging malfunctions, the charging current cannot be detected, and the charging completion determination based on the detected current of the first current sensor 22 cannot be implemented. In this case, although it is possible to use the second current sensor 23 instead of the first current sensor 22 during charging, the detection resolution of the second current sensor 23 is lower than that of the first current sensor 22, and the error is larger. Therefore, the accuracy of the charging completion determination may be reduced.

[0053] Therefore, in this embodiment, the battery control device 70 includes: an anomaly determination unit that determines whether the first current sensor 22 is malfunctioning; a first charging control unit that, when determining that the first current sensor 22 is not malfunctioning, performs a charging completion determination based on the detected current of the first current sensor 22 when charging is performed by the external charging device 100; and a second charging control unit that, when determining that the first current sensor 22 is malfunctioning, uses a second current sensor 23 instead of the first current sensor 22, and performs a charging completion determination based on the detected current of the second current sensor 23 when charging is performed by the external charging device 100. The determination criteria for charging completion are different in the first charging control unit and the second charging control unit.

[0054] Figure 3 This is a flowchart illustrating the charging control process steps during battery charging by the external charging device 100. This process is performed by the battery control device 70 at predetermined cycles when the IG switch is off and a request for external charging by the main battery 21 is generated.

[0055] exist Figure 3 In step S11, it is determined whether the main battery 21 is being charged by the external charging device 100. For example, if a charging cable is connected, it is determined whether the battery control device 70 can communicate with the external charging device 100. Then, if step S11 is affirmative, the process proceeds to step S12.

[0056] In step S12, it is determined whether the terminal voltage Vb of the main battery 21 is lower than the specified voltage Vth. If step S12 is affirmative, proceed to step S13. In step S13, CC charging is performed, where the charging current of the external charging device 100 is set to a constant value. During CC charging, the terminal voltage of the main battery 21 gradually increases over time. Once the specified voltage Vth is reached, step S12 is negated, and proceed to step S14. In step S14, CV charging is performed, where the charging voltage of the external charging device 100 is set to a constant value.

[0057] In step S15, it is determined whether the first current sensor 22 is functioning properly. Furthermore, the method for determining whether the first current sensor 22 is malfunctioning can be arbitrary; for example, if the detected current of the first current sensor 22 remains at zero or at its maximum detected value, it is determined that an malfunction has occurred. The malfunction determination process for the first current sensor 22 is implemented during the IG switch switching and external charging, and the malfunction determination result is stored in backup memory such as backup RAM or EEPROM.

[0058] If the first current sensor 22 is functioning normally, proceed to step S16 to acquire the detection current Ia1 of the first current sensor 22. Next, in step S17, determine whether the detection current Ia1 of the first current sensor 22 is below a first threshold Ith1. Specifically, the first threshold Ith1 is a current value (cutoff current) used as a reference for determining charging completion; if the detection current Ia1 is below the first threshold Ith1, it is determined that charging is complete. If step S17 is negative, the process ends directly. In this case, CV charging continues. Alternatively, if step S17 is positive, proceed to step S18 and end external charging.

[0059] Additionally, if the first current sensor 22 is malfunctioning, proceed to step S19 to determine whether the second current sensor 23 is functioning correctly. Then, if the second current sensor 23 is functioning correctly, proceed to step S20. In step S20, the detection current Ia2 of the second current sensor 23 is acquired. Next, in step S21, it is determined whether the detection current Ia2 of the second current sensor 23 is below a second threshold Ith2. The second threshold Ith2 is a current value used as a reference for determining charging completion, replacing the first threshold Ith1, where Ith2 > Ith1. Then, if it is determined that the detection current Ia2 is below the second threshold Ith2, proceed to step S18 and end external charging. Furthermore, if both the first current sensor 22 and the second current sensor 23 are malfunctioning, proceed to step S18 and end external charging.

[0060] According to the above-described embodiment, the following excellent effects can be obtained.

[0061] In the event of a malfunction in the first current sensor 22, a second current sensor 23 is used instead of the first current sensor 22, and the charging completion determination during the charging of the main battery 21 is performed based on the detected current I a2 of the second current sensor 23. Furthermore, specifically, the criteria for determining charging completion are different in the charging control based on the detected current I a1 of the first current sensor 22 and the charging control based on the detected current I a2 of the second current sensor 23. In this case, when the second current sensor 23 is used instead of the first current sensor 22 in determining the charging completion of the main battery 21, the accuracy of the determination may decrease due to the difference in the detection range (error magnitude) of the current sensors 22 and 23. However, since the determination criteria for charging completion differ with the change of current sensor, the decrease in the accuracy of the charging completion determination can be suppressed.

[0062] More specifically, a second threshold Ith2, which is larger than the first threshold Ith1 used to determine charging completion when the first current sensor 22 is used, is used as the reference value for determining charging completion. This allows for earlier determination that charging is complete and the charging process can be stopped, thus suppressing overcharging.

[0063] Hereinafter, another embodiment that modifies a portion of the structure of the first embodiment will be described. Furthermore, in the following description, the differences from the first embodiment will be the focus, and the same symbols will be used to mark structures identical to those in the first embodiment, with their descriptions omitted as appropriate.

[0064] (Second Implementation)

[0065] In this embodiment, when the charging completion determination is made based on the detection current I a2 of the second current sensor 23, the target voltage in CV charging is set to a lower voltage than when the charging completion determination is made based on the detection current I a1 of the first current sensor 22.

[0066] Figure 4 This is a flowchart illustrating the charging control processing steps in this embodiment. This processing is implemented to replace the above-described steps. Figure 3 The processing. Additionally, in Figure 4 In China, for the sake of Figure 3 The same process is labeled with the same step number, and its description is omitted.

[0067] exist Figure 4In step S19, if the second current sensor 23 is determined to be normal, i.e., if the charging completion determination is based on the detection current Ia2 of the second current sensor 23, then in step S31, the target voltage for CV charging is set. In this case, the target voltage for CV charging is set to a voltage lower than the voltage used when the charging completion determination is based on the detection current Ia1 of the first current sensor 22. Then, the processing of determining whether the detection current Ia2 of the second current sensor 23 is below the second threshold Ith2 (steps S20 and S21) is as described above.

[0068] When using the second current sensor 23, which has a lower detection resolution, the completion determination during CV charging is delayed when charging is proceeding rapidly, potentially leading to overcharging. Furthermore, during CV charging, the slope of the current change gradually decreases as the main battery 21 charges. Therefore, it is hypothesized that by advancing the completion determination, the slope of the current change at the time of completion determination would become steeper. To address this, as described above, the target voltage during CV charging is set to a voltage lower than the voltage at which the completion determination is made based on the detected current Ia1 of the first current sensor 22. Therefore, overcharging suppression can be ideally achieved.

[0069] (Third Implementation)

[0070] In this embodiment, when determining that charging is complete based on the current I a2 detected by the second current sensor 23, the earlier of either the current I a2 detected by the second current sensor 23 being below the second threshold I th2 or the start of CV charging (constant voltage charging) and the elapsed time being specified, is determined to be charging complete.

[0071] Figure 5 This is a flowchart illustrating the charging control processing steps in this embodiment. This processing is implemented to replace the above-described steps. Figure 3 The processing. Additionally, in Figure 5 In China, for the sake of Figure 3 The same process is labeled with the same step number, and its description is omitted.

[0072] exist Figure 5 In step S21, it is determined whether the detected current Ia2 of the second current sensor 23 is below the second threshold Ith2. If step S21 is negative, proceed to step S41 to determine whether a predetermined time has elapsed since the start of CV charging. If step S41 is negative, the process ends directly. If step S41 is positive, proceed to step S18 and end external charging.

[0073] That is, according to steps S21 and S41, if the detected current I a2 of the second current sensor 23 becomes lower than the second threshold Ith2 or if the specified time has elapsed since the start of CV charging, it is determined that charging has been completed.

[0074] In this case, by considering that the detection resolution of the second current sensor 23 is lower than that of the first current sensor 22, i.e., the error is larger, early charging completion determination can suppress overcharging. Furthermore, before the charging completion determination based on the second threshold Ith2 is established, if a predetermined time has elapsed since the start of CV charging, charging is determined to be complete at the point when that predetermined time has elapsed. Therefore, when using the second current sensor 23, even if it is assumed that charging completion determination cannot be accurately performed due to errors included in the detected current, the implementation of CV charging can be limited based on the elapsed time since the start of CV charging, thereby suppressing overcharging of the main battery 21.

[0075] (Fourth Implementation)

[0076] In this embodiment, when external charging is performed by the external charging device 100, the charging mode can be selected as either a normal charging mode or a fast charging mode. In the fast charging mode, the charging current is increased to accelerate the charging speed compared to the normal charging mode. Furthermore, in the event of an malfunction of the first current sensor 22, if the charging mode is the normal charging mode, charging is determined to be complete when the detected current Ia2 of the second current sensor 23 falls below the second threshold Ith2; if the charging mode is the fast charging mode, charging is determined to be complete based on the completion of CC charging.

[0077] Figure 6 This is a flowchart illustrating the charging control processing steps in this embodiment. This processing is implemented to replace the above-described steps. Figure 3 The processing. Additionally, in Figure 6 In China, for the sake of Figure 3 The same process is labeled with the same step number, and its description is omitted.

[0078] exist Figure 6If the first current sensor 22 is determined to be malfunctioning in step S15, the process proceeds to step S51 to determine whether the charging mode is a normal charging mode. If it is a normal charging mode, the process proceeds to step S19, where a charging completion determination is made based on the detected current Ia2 of the second current sensor 23 (steps S19-S21). Alternatively, if it is a fast charging mode, the process proceeds to step S18, and external charging ends. That is, the determination in step S51 occurs after a negative result in step S12. Since CC charging has already been completed, external charging ends immediately if a negative result is found in step S51.

[0079] When using the second current sensor 23 with lower detection resolution, during CV charging, the charging completion determination may be delayed when charging is proceeding rapidly, potentially leading to overcharging. Furthermore, this possibility increases in fast charging mode. To address this, the above-described structure allows for earlier timing of the charging completion determination in fast charging mode compared to normal charging mode, thus suppressing overcharging.

[0080] (Fifth Implementation)

[0081] In this embodiment, the system includes a correction unit. When determining charging completion by comparing the detected current Ia2 from the second current sensor 23 with a second threshold Ith2, this correction unit acquires the terminal voltage of the main battery 21 after charging is complete and corrects the second threshold Ith2 based on this terminal voltage. Here, based on the terminal voltage (open-circuit voltage OCV) of the main battery 21, the SOC of the main battery 21, i.e., the amount of charge relative to a fully charged state, can be determined. In this case, the timing of charging completion determination using the second threshold Ith2 can be assessed to determine whether the timing of charging completion is appropriate.

[0082] Figure 7 This is a flowchart illustrating the correction process for the second threshold I th2. This process is described above. Figure 3 After the implementation of the charging control process, that is, after the external charging is performed by the external charging device 100, it is implemented by the battery control device 70.

[0083] exist Figure 7 In step S61, when external charging is performed by the external charging device 100, a determination is made as to whether charging is complete by comparing the detected current Ia2 of the second current sensor 23 with the second threshold Ith2. Then, if step S61 is negative, the process ends directly; if step S61 is positive, the process proceeds to step S62.

[0084] In step S62, the battery terminal voltage detected by voltage sensor 24 in the non-powered state of the main battery 21 is acquired. In the subsequent step S63, the second threshold Ith2 is corrected based on the battery terminal voltage. Specifically, it is determined whether the battery terminal voltage enters a predetermined voltage range. If the battery terminal voltage enters the voltage range, the second threshold Ith2 remains unchanged (no correction). Alternatively, if the battery terminal voltage is higher than the upper limit of the voltage range, the second threshold Ith2 is increased as overcharging; if the battery terminal voltage is lower than the lower limit of the voltage range, the second threshold Ith2 is decreased as undercharging. Additionally, in step S63, the SOC of the main battery 21 can also be calculated based on the battery terminal voltage (open circuit voltage OCV), and the second threshold Ith2 can be corrected based on whether the SOC enters a predetermined range.

[0085] Next, in step S64, the corrected second threshold I th2 is stored as a learning value in backup memory such as backup RAM or EEPROM. If the second threshold I th2 was previously stored, it is updated using the corrected value. Then, during the next external charging, the second threshold I th2 stored in the backup memory is appropriately used to determine charging completion.

[0086] Ideally, the magnitude of the error contained in the detection current Ia2 of the second current sensor 23 should be considered when determining the second threshold Ith2 for comparison with the detection current Ia2 of the second current sensor 23. To suppress overcharging, a large margin is desirable. However, on the other hand, if the second threshold Ith2 is too large, the charging of the main battery 21 may be excessively restricted. To address this, the above structure not only suppresses overcharging of the main battery 21 but also suppresses undercharging.

[0087] (Other implementation methods)

[0088] For example, the above implementation method can be modified as described below.

[0089] • It can also be configured to change the second threshold I th2 according to the aging degree of the main battery 21. Figure 8 This is a flowchart representing the setting process of the second threshold I th2, which is implemented by the battery control device 70.

[0090] exist Figure 8 In step S71, aging information representing the degree of aging of the main battery 21 is obtained. This aging information is, for example, the internal resistance of the main battery 21, and the degree of aging is represented by the difference from the initial value when the battery was new. In the subsequent step S72, a second threshold Ith2 is set based on the battery aging information. At this time, for example, using Figure 9 The greater the degree of battery aging, the larger the value of the second threshold Ith2 should be.

[0091] Next, in step S73, the second threshold Ith2 set in step S72 is stored as a learning value in the backup memory. If the second threshold Ith2 was previously stored, it is updated using the current setting value. Then, during the next external charging, the second threshold Ith2 stored in the backup memory is appropriately used to determine charging completion.

[0092] In the above embodiment, the first current sensor 22, whose first range is set as the current detection range, is used as the current sensor during battery charging, and the second current sensor 23, whose second range is wider than the first range, is used as the current sensor for motor control. However, this can be modified. For example, it is also possible to configure all of the above current sensors as current sensors used during battery charging, using the second current sensor 23 for charging control during the initial charging stage when the charging current is above a predetermined value, and using the first current sensor 22 for charging control after the charging current falls below the predetermined value.

[0093] • In the above embodiments, this disclosure is applied to the power supply system of a vehicle, but it can also be applied to power supply systems other than those used in vehicles.

[0094] The control unit and methods described in this disclosure can also be implemented using a dedicated computer, which is provided by comprising a processor and memory, the processor being programmed to perform one or more functions embodied in the computer program. Alternatively, the control unit and methods described in this disclosure can be implemented using a dedicated computer, which is provided by comprising a processor composed of one or more dedicated hardware logic circuits. Alternatively, the control unit and methods described in this disclosure can be implemented using one or more dedicated computers, which are constituted by a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. Furthermore, the computer program can also be stored on a computer-readable non-transitory tangible storage medium as instructions executable by a computer.

[0095] While this disclosure has been described based on embodiments, it should be understood that this disclosure is not limited to the above embodiments and structures. This disclosure also includes various modifications and equivalent variations. Furthermore, various combinations and arrangements, and consequently, combinations and arrangements containing only one element, or more than or less thereof, also fall within the scope and spirit of this disclosure.

Claims

1. A battery control device, The battery control device is applicable to power systems including a first current sensor and a second current sensor for detecting the current flowing through the battery. When the battery is charged by a charging device, charging completion is determined based on the detected current of the first current sensor (of the first and second current sensors). The first current sensor has a first range defined as its current detection range, and the second current sensor has a second range wider than the first range defined as its current detection range. The battery control device includes: An anomaly determination unit determines whether the first current sensor has malfunctioned. A first charging control unit, which, when determining that the first current sensor is not malfunctioning, performs a charging completion determination based on the detected current of the first current sensor when charging is initiated by the charging device; and The second charging control unit, when determining that the first current sensor has malfunctioned, uses the second current sensor instead of the first current sensor, and performs a charging completion determination based on the detected current of the second current sensor when charging is performed by the charging device. The criteria for determining the completion of charging are different in the first charging control unit and the second charging control unit.

2. The battery control device as described in claim 1, characterized in that, The first charging control unit determines that charging is complete when the detected current from the first current sensor falls below a first threshold. The second charging control unit determines that charging is complete when the detected current of the second current sensor is below a second threshold that is greater than the first threshold.

3. The battery control device as described in claim 2, characterized in that, When the battery is charged by the charging device, the battery control device performs constant current charging by setting the charging current of the charging device to a constant value to charge the battery, and after the constant current charging, performs constant voltage charging by setting the charging voltage of the charging device to a constant value to charge the battery, wherein... The second charging control unit sets the target voltage in the constant voltage charging to be lower than the voltage when the constant voltage charging is performed by the first charging control unit.

4. The battery control device as described in claim 1, characterized in that, When the battery is charged by the charging device, the battery control device performs constant current charging by setting the charging current of the charging device to a constant value to charge the battery, and after the constant current charging, performs constant voltage charging by setting the charging voltage of the charging device to a constant value to charge the battery, wherein... The first charging control unit determines that charging is complete when the detected current from the first current sensor falls below a first threshold. The second charging control unit determines that charging is complete based on either the earlier of the following: the current detected by the second current sensor is below a second threshold that is greater than the first threshold, or the constant voltage charging has started and a predetermined time has elapsed.

5. The battery control device as described in claim 1, characterized in that, When the battery is charged by the charging device, the battery control device performs constant current charging by setting the charging current of the charging device to a constant value to charge the battery. After constant current charging, it performs constant voltage charging by setting the charging voltage of the charging device to a constant value to charge the battery. Furthermore, as a charging mode, it can select between a normal charging mode and a fast charging mode. The first charging control unit determines that charging is complete when the detected current from the first current sensor falls below a first threshold. If the charging mode is the normal charging mode, the second charging control unit determines that charging is complete based on the second current sensor detecting that the current is below a second threshold that is greater than the first threshold. If the charging mode is the fast charging mode, the second charging control unit determines that charging is complete based on the completion of constant current charging.

6. The battery control device as described in any one of claims 2 to 5, characterized in that, The battery control device includes a correction unit. When the second charging control unit determines that charging is complete using the second threshold, the correction unit acquires the terminal voltage of the battery after charging is complete and corrects the second threshold based on the terminal voltage.

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