On-vehicle control device

Abstract

An on-vehicle control device (10) has a measurement unit (e.g., a control unit (14)) that performs measurement processing, and a discharge control unit (e.g., said control unit (14)) that controls a discharge unit. The measurement processing is for causing a charging unit to perform a charging operation, and measuring internal resistance of a power storage unit (3) on the basis of a voltage change of the power storage unit (3) before and after the start of the charging operation. The measurement unit: performs the measurement processing when measurement conditions are satisfied during a measurement target period from when a vehicle enters the start state to when the vehicle enters the parking state; and omits the measurement processing when the measurement conditions are not satisfied during the measurement target period. The measurement conditions include a condition that the voltage of the power storage unit (3) is less than a determination value. When the number of times in which the measurement processing is omitted at the time when the vehicle enters the parking state is equal to or greater than an upper limit value, the discharge control unit causes the discharge unit to perform a discharge operation until the voltage of the power storage unit (3) becomes less than a first threshold value which is equal to or less than the determination value.

Description

In-vehicle control device

[0001] The present disclosure relates to an in-vehicle control device.

[0002] Conventionally, there are known techniques for measuring the internal resistance of a vehicle battery. For example, Patent Document 1 discloses a power storage system. This power storage system includes a battery, a voltage sensor that detects the voltage value of the battery, a current sensor that detects the current value of the battery, and a control device. The control device derives an estimate of the current internal resistance of the battery based on the voltage value detected by the voltage sensor and the current value detected by the current sensor.

[0003] Japanese Patent Application Laid-Open No. 2023-102052

[0004] When attempting to measure the internal resistance at the start of a vehicle, for example, one approach is to charge the battery at the start of the vehicle, flow a current, and measure the internal resistance based on the voltage change before and after the start of charging. However, this method has the risk of causing the battery voltage to exceed the rated voltage due to charging. To prevent this, it is possible to discharge the battery to a certain extent before parking the vehicle, anticipating the increase in voltage before and after the start of charging. However, the voltage increase before and after the start of charging varies depending on the internal resistance during charging, and the internal resistance varies depending on the temperature of the storage unit. When the vehicle is parked, the temperature of the storage unit at the next start cannot be determined, so it is impossible to determine how much to discharge. Discharging the battery so that the rated voltage is not exceeded at any temperature during charging is likely to result in unnecessary discharge. Conversely, there is a concern that the internal resistance cannot be measured for a long period of time if the battery is not fully discharged or if it is not discharged at all.

[0005] The present disclosure aims to provide a technology that can easily prevent the process of measuring the internal resistance of a storage unit from being performed for a long period of time, while suppressing unnecessary discharge and preventing the voltage of the storage unit from exceeding the rated voltage when a vehicle is started.

[0006] The in-vehicle control device disclosed herein is an in-vehicle control device included in an in-vehicle system including: a power supply unit; a storage unit; a charging unit that performs a charging operation to charge the storage unit based on power from the power supply unit; and a discharging unit that performs a discharging operation to discharge the storage unit, and includes: a measurement unit that performs a measurement process; and a discharge control unit that controls the discharge unit, wherein the measurement process is a process that causes the charging unit to perform the charging operation and measures an internal resistance of the storage unit based on a voltage change of the storage unit before and after the start of the charging operation, the measurement unit performs the measurement process if a measurement condition is met during a measurement period from when the vehicle is started to when the vehicle is parked, and omits the measurement process if the measurement condition is not met during the measurement period, the measurement condition includes a condition that the voltage of the storage unit is less than a judgment value, and the discharge control unit, when the number of times the measurement process has been skipped when the vehicle is parked is equal to or greater than an upper limit value, causes the discharge unit to perform the discharge operation until the voltage of the storage unit becomes less than a first threshold that is equal to or less than the judgment value.

[0007] The technology disclosed herein suppresses unnecessary discharge and makes it easy to prevent the process of measuring the internal resistance of the power storage unit from being performed for a long period of time so that the voltage of the power storage unit does not exceed the rated voltage when the vehicle is started.

[0008] FIG. 1 is a schematic diagram illustrating an in-vehicle system including an in-vehicle control device according to a first embodiment. FIG. 2 is an explanatory diagram illustrating a schematic configuration of a cell balance circuit and its surroundings. FIG. 3 is a part of a flowchart illustrating the flow of processing performed by a control unit. FIG. 4 is the remaining part of the flowchart illustrating the flow of processing performed by the control unit. FIG. 5 is an explanatory diagram conceptually illustrating the operation of the control unit.

[0009] [Description of Embodiments of the Present Disclosure] In the following, embodiments according to the present disclosure are listed and exemplified.

[0010] [1] An in-vehicle control device included in an in-vehicle system including a power supply unit, a power storage unit, a charging unit that performs a charging operation to charge the power storage unit based on power from the power supply unit, and a discharging unit that performs a discharging operation to discharge the power storage unit, the in-vehicle control device having: a measurement unit that performs a measurement process; and a discharge control unit that controls the discharge unit, wherein the measurement process is a process of causing the charging unit to perform the charging operation and measuring an internal resistance of the power storage unit based on a voltage change of the power storage unit before and after the start of the charging operation, the measurement unit performs the measurement process if a measurement condition is met during a measurement period from when the vehicle is started to when the vehicle is parked, and omits the measurement process if the measurement condition is not met during the measurement period, the measurement condition includes a condition that the voltage of the power storage unit is less than a determination value, and the discharge control unit, when the number of times the measurement process has been skipped when the vehicle is parked is equal to or greater than an upper limit value, causes the discharge unit to perform the discharge operation until the voltage of the power storage unit becomes less than a first threshold that is equal to or less than the determination value.

[0011] This in-vehicle control device can perform the measurement process when the measurement condition is met. The measurement condition includes a condition that the voltage of the power storage unit is less than a determination value. Therefore, this in-vehicle control device can perform the measurement process so that the voltage of the power storage unit does not exceed the rated voltage by setting the determination value so that the voltage of the power storage unit does not exceed the rated voltage even when the measurement process is performed. Furthermore, even if the measurement condition continues not to be met, if the number of skipped times reaches or exceeds an upper limit, this in-vehicle control device discharges the power storage unit until the voltage of the power storage unit becomes less than the first threshold when the vehicle is parked. This makes it easier for the measurement condition to be met the next time the vehicle is started, and makes it easier for the measurement process to be performed. In other words, this in-vehicle control device can easily prevent the measurement process from not being performed for a long period of time while suppressing unnecessary discharge.

[0012] [2] The in-vehicle control device according to [1], wherein the discharge control unit sets the first threshold value based on a measurement value measured in the most recent measurement process.

[0013] This on-board control device can set the first threshold value taking into account the measurement value measured in the most recent measurement process.

[0014] [3] The in-vehicle control device described in [1] or [2], wherein in the measurement process, the measurement unit causes the charging unit to perform the charging operation so that a constant current flows through the storage unit, and measures the internal resistance of the storage unit based on the constant current flowing through the storage unit and a change in voltage of the storage unit before and after the start of the charging operation.

[0015] This in-vehicle control device can measure the internal resistance of the power storage unit based on a constant current flowing through the power storage unit and a change in the voltage of the power storage unit before and after the start of a charging operation. When a constant current flows, the voltage of the power storage unit is likely to rise and exceed the rated voltage. In this regard, this in-vehicle control device performs the measurement process on the condition that the voltage of the power storage unit is less than a determination value, and therefore can easily prevent the voltage of the power storage unit from exceeding the rated voltage when the measurement process is performed.

[0016] [4] The vehicle-mounted control device described in any one of [1] to [3], wherein the discharge control unit causes the discharge unit to perform the discharge operation until the voltage of the storage unit becomes less than a second threshold value that is greater than the first threshold value when the number of times the measurement process is omitted when the vehicle is in the parked state is less than the upper limit value.

[0017] The in-vehicle control device can discharge the power storage unit until the voltage of the power storage unit becomes less than the second threshold, even if the number of times the measurement process has been skipped when the vehicle is parked is less than the upper limit. Therefore, the in-vehicle control device can increase the likelihood that the voltage of the power storage unit will be less than the determination value when the vehicle is started, compared to a case in which the power storage unit is not discharged. As a result, the in-vehicle control device can increase the likelihood that the measurement process will be performed.

[0018] [5] The vehicle-mounted control device according to [4], wherein the discharge control unit sets the second threshold value based on the ambient temperature of the power storage unit in the parked state or immediately after the vehicle is started.

[0019] This vehicle-mounted control device can set the second threshold value based on the temperature in an environment that is less affected by the vehicle's air conditioning.

[0020] [6] The vehicle-mounted control device according to any one of [1] to [5], wherein the measurement conditions include a condition that the voltage of the storage unit is less than the determination value and the temperature around the storage unit is equal to or higher than a threshold temperature.

[0021] This in-vehicle control device can perform measurement processing so that the voltage of the storage unit does not exceed the rated voltage by setting a judgment value so that the voltage of the storage unit does not exceed the rated voltage even when measurement processing is performed when the ambient temperature of the storage unit is above a threshold temperature.

[0022] [Details of the embodiment of the present disclosure] <First embodiment> 1. Configuration of in-vehicle system 1 Fig. 1 shows an in-vehicle system 1 including an in-vehicle control device 10. The in-vehicle system 1 is a system mounted on a vehicle. The in-vehicle system 1 includes a power supply unit 2, a power storage unit 3, and a voltage conversion unit 4.

[0023] The power supply unit 2 is, for example, a DC power supply that generates a DC voltage, such as a battery. The power supply unit 2 is, for example, a lithium ion battery, a sodium ion battery, etc. The power supply unit 2 is, for example, a high-voltage battery that has a higher output voltage than the power storage unit 3.

[0024] The power storage unit 3 is configured by a power storage element such as a lithium ion capacitor or a lithium ion battery. The power storage unit 3 is, for example, a low-voltage battery having a lower output voltage than the power supply unit 2. The internal resistance of the power storage unit 3 increases as the temperature decreases.

[0025] The voltage conversion unit 4 corresponds to an example of a charging unit and a discharging unit. The voltage conversion unit 4 is provided between the power supply unit 2 and the power storage unit 3. The voltage conversion unit 4 increases or decreases the voltage input from the first conduction path 81 on the power supply unit 2 side and outputs the voltage to the second conduction path 82 on the power storage unit 3 side. As a result, the power storage unit 3 is charged with power from the power supply unit 2. In other words, the voltage conversion unit 4 performs a charging operation to charge the power storage unit 3 based on the power from the power supply unit 2. Furthermore, the voltage conversion unit 4 increases or decreases the voltage input from the second conduction path 82 on the power storage unit 3 side and outputs the voltage to the first conduction path 81 on the power supply unit 2 side. As a result, power from the power storage unit 3 is supplied to the power supply unit 2, and the power storage unit 3 is discharged. In other words, the voltage conversion unit 4 performs a discharging operation to discharge the power storage unit 3.

[0026] The in-vehicle system 1 includes an in-vehicle control device 10. The in-vehicle control device 10 has a current detection unit 11, a voltage detection unit 12, a temperature detection unit 13, and a control unit 14.

[0027] The current detection unit 11 is configured by, for example, a known current sensor. The current detection unit 11 detects the current flowing through the second conductive path 82. The current detection unit 11 detects the current flowing through the power storage unit 3. The current detection unit 11 outputs a signal indicating the detected value to the control unit 14.

[0028] The voltage detection unit 12 is configured by, for example, a known current detection circuit. The voltage detection unit 12 detects the voltage of the second conductive path 82. The voltage detection unit 12 detects the voltage of the power storage unit 3. The voltage detection unit 12 outputs a signal indicating the detected value to the control unit 14.

[0029] The temperature detection unit 13 is configured by, for example, a known temperature sensor. The temperature detection unit 13 detects the temperature around the power storage unit 3. The temperature detection unit 13 outputs a signal indicating the detected value to the control unit 14.

[0030] The control unit 14 includes, for example, a microcomputer. The control unit 14 detects the current flowing through the power storage unit 3 based on the signal output from the current detection unit 11. The control unit 14 detects the voltage of the power storage unit 3 based on the signal output from the voltage detection unit 12. The control unit 14 detects the ambient temperature of the power storage unit 3 based on the signal output from the temperature detection unit 13. The control unit 14 controls the voltage conversion unit 4.

[0031] The control unit 14 corresponds to an example of a measurement unit. The control unit 14 performs a measurement process. The measurement process is a process of causing the voltage conversion unit 4 to perform a charging operation and measuring the internal resistance of the power storage unit 3 based on a voltage change in the power storage unit 3 before and after the start of the charging operation. When performing the measurement process, the control unit 14 causes the voltage conversion unit 4 to perform a charging operation so that a constant current flows through the power storage unit 3. The control unit 14 then measures the internal resistance of the power storage unit 3 based on the constant current I flowing through the power storage unit 3 and the voltage change ΔV in the power storage unit 3 before and after the start of the charging operation. For example, the control unit 14 measures the internal resistance of the power storage unit 3 using the following formula (A): Internal resistance of the power storage unit 3 = ΔV / I Formula (A) Note that "before the start of the charging operation" refers to a state in which no current flows through the power storage unit 3.

[0032] When a constant current is passed through the power storage unit 3 in the measurement process, the voltage of the power storage unit 3 is likely to rise and exceed the rated voltage of the power storage unit 3. For this reason, the in-vehicle control device 10 is configured as follows so that the voltage of the power storage unit 3 does not exceed the rated voltage of the power storage unit 3.

[0033] The control unit 14 performs the measurement process when a measurement condition is met during a measurement period from when the vehicle is in a start state to when it is in a parked state. The control unit 14 omits the measurement process when the measurement condition is not met during the measurement period. The start state is, for example, when the start switch of the vehicle is on. The parked state is, for example, when the start switch of the vehicle is off. The start switch is, for example, an ignition switch if the vehicle is an engine-equipped vehicle, or a power switch if the vehicle is an electric vehicle. The measurement condition includes a condition that the voltage of the power storage unit 3 is less than a predetermined judgment value. In this embodiment, the measurement condition includes a condition that the voltage of the power storage unit 3 is less than a predetermined judgment value and that the temperature around the power storage unit 3 is equal to or higher than a threshold temperature. The judgment value is set to a value that prevents the voltage of the power storage unit 3 from exceeding the rated voltage even when the measurement process is performed when the temperature around the power storage unit 3 is equal to or higher than the threshold temperature.

[0034] The control unit 14 corresponds to an example of a discharge control unit. When the number of times measurement processing has been skipped when the vehicle is parked is equal to or greater than an upper limit, the control unit 14 causes the voltage conversion unit 4 to perform a discharge operation until the voltage of the storage unit 3 becomes less than a first threshold. In this embodiment, the first threshold is the same value as the determination value, but may be a value smaller than the determination value.

[0035] The first threshold value may be a fixed value or a value that can be changed. If the first threshold value is a value that can be changed, the control unit 14 sets the first threshold value based on, for example, a measurement value measured in the most recent measurement process. For example, the control unit 14 sets the first threshold value to a smaller value as the measurement value increases. The control unit 14 stores correspondence data indicating the correspondence between the measurement value and the first threshold value in advance, and sets the first threshold value based on the measurement value and the correspondence data. The correspondence data may be function data or table data.

[0036] The function data may be, for example, the following formula (1): First threshold value=VR−(I×measured value+C1) formula (1) where I is a constant current flowing through the power storage unit 3 in the measurement process, VR is a rated voltage of the power storage unit 3, and C1 is a constant.

[0037] Furthermore, the control unit 14 may set the first threshold value based on the measurement value measured in the most recent measurement process and the temperature around the power storage unit 3 in a parked state or immediately after the vehicle is started. In this case, the function data may be, for example, the following formula (2): First threshold value = VR - (I × measurement value × temperature coefficient + C2) Formula (2) where I is the constant current flowing through the power storage unit 3 in the measurement process. VR is the rated voltage of the power storage unit 3. The temperature coefficient is a coefficient that is set based on the temperature around the power storage unit 3. The temperature coefficient is a value that increases as the temperature around the power storage unit 3 decreases. C2 is a constant.

[0038] If the number of times measurement processing has been omitted when the vehicle is parked is less than the upper limit value, the control unit 14 causes the voltage conversion unit 4 to perform a discharge operation until the voltage of the storage unit 3 becomes less than a second threshold value that is greater than the first threshold value.

[0039] The second threshold value may be a preset fixed value or a variable value. For example, the control unit 14 may set the second threshold value based on the ambient temperature of the power storage unit 3 while the vehicle is parked or immediately after the vehicle is started.

[0040] Furthermore, when the control unit 14 causes the voltage conversion unit 4 to perform a discharge operation when the vehicle is parked, the control unit 14 performs cell balance control to adjust the cell balance of the power storage unit 3 in parallel with the discharge operation.

[0041] As shown in FIG. 2 , the power storage unit 3 is composed of multiple battery cells 3A. The in-vehicle system 1 includes a cell balance circuit 21 and voltage signal lines 22. The cell balance circuit 21 performs cell balancing to correct imbalances in the amounts of stored electricity among the battery cells 3A, thereby equalizing the voltages or capacities of the individual battery cells 3A. The discharge operation for equalization can be performed using multiple cell discharge units 21A, each corresponding to the multiple battery cells 3A. The multiple voltage signal lines 22 are electrically connected to the inter-battery electrodes or end electrodes of the multiple battery cells 3A connected in series. Each voltage signal line 22 is electrically connected to the electrode to which it is connected and inputs a signal indicating the voltage of the electrode to which it is connected to the control unit 14. Note that each voltage signal line 22 includes a fuse and an inductor. The control unit 14 adjusts the cell balance of the power storage unit 3 by performing cell balancing control, which causes the cell balance circuit 21 to perform the cell balancing operation.

[0042] 2. Operation Example of the In-Vehicle Control Device 10 When a start condition is met, the control unit 14 performs the processing shown in Figures 3 and 4. The start condition is, for example, that the vehicle is in a start state, specifically, that the start switch is switched to the on state.

[0043] When the vehicle is in a start-up state, the control unit 14 acquires the voltage of the power storage unit 3 and the temperature around the power storage unit 3 in step S11. Then, the control unit 14 determines in step S12 whether the temperature around the power storage unit 3 is equal to or higher than a preset threshold temperature. If the control unit 14 determines that the temperature around the power storage unit 3 is not equal to or higher than the threshold temperature, the control unit 14 determines in step S13 whether a certain time has elapsed since it was determined that the temperature around the power storage unit 3 is not equal to or higher than the threshold temperature. The control unit 14 enters a standby state until the certain time has elapsed. If the control unit 14 determines that the certain time has elapsed, the control unit 14 determines in step S14 whether the vehicle is in a parked state. That is, the control unit 14 determines whether the start switch has been switched to an OFF state. If the control unit 14 determines that the vehicle is not in a parked state, the process returns to step S11. That is, the control unit 14 repeats the processes of steps S11 to S14 until the temperature around the power storage unit 3 is equal to or higher than the threshold temperature or until the vehicle is in a parked state.

[0044] If the control unit 14 determines in step S12 that the temperature around the power storage unit 3 is equal to or higher than the threshold temperature, the process proceeds to step S21 in FIG. 4 . In step S21, the control unit 14 determines whether the voltage of the power storage unit 3 is less than the determination value. If the control unit 14 determines that the voltage of the power storage unit 3 is less than the determination value, the control unit 14 performs a measurement process in step S22 and clears an omission counter in step S23. The omission counter is a counter that counts the number of times that a measurement process was not performed during the measurement period. If the control unit 14 determines in step S21 that the voltage of the power storage unit 3 is not less than the determination value, the control unit 14 increments the omission counter by 1 in step S24.

[0045] After step S23 or step S24, the control unit 14 proceeds to step S25. In step S25, the control unit 14 determines whether the vehicle is in a parked state. If the control unit 14 determines that the vehicle is not in a parked state, the control unit 14 repeats the process of step S25 until the vehicle is in a parked state. After step S23 or step S24, the control unit 14 repeatedly determines whether a charging condition is met during the period until the vehicle is in a parked state. The charging condition is, for example, that the voltage of the power storage unit 3 is equal to or lower than a predetermined charging start voltage. If the control unit 14 determines that the charging condition is met, the control unit 14 causes the voltage conversion unit 4 to perform a charging operation until the voltage of the power storage unit 3 reaches a full charge voltage VMAX. This charging operation is referred to as a normal charging operation to distinguish it from a charging operation during measurement processing. The full charge voltage VMAX is a value greater than the charging start voltage and less than the rated voltage. The full charge voltage VMAX may be fixed or may vary depending on the deterioration state of the power storage unit 3. When causing the voltage conversion unit 4 to perform a normal charging operation, if the voltage of the power storage unit 3 is equal to or higher than a reference value, the control unit 14 causes the voltage conversion unit 4 to perform the normal charging operation so that the output voltage becomes a target voltage. This allows the in-vehicle control device 10 to charge the power storage unit 3 while suppressing the output voltage. On the other hand, if the voltage of the power storage unit 3 is lower than the reference value, the control unit 14 causes the voltage conversion unit 4 to perform the normal charging operation so that the output current becomes the target current. This allows the power storage unit 3 to be rapidly charged. The reference value is a value equal to or lower than the charge start voltage.

[0046] If the control unit 14 determines in step S25 that the vehicle has entered a parked state, the process proceeds to step S16 in Fig. 3. If the control unit 14 determines in step S14 that the vehicle has entered a parked state, the control unit 14 increments the omission counter by 1 in step S15, and the process proceeds to step S16. In other words, if the control unit 14 does not perform measurement processing during the measurement target period, the control unit 14 increments the omission counter by 1.

[0047] In step S16, the control unit 14 determines whether the value of the skip counter is equal to or greater than the upper limit. If the control unit 14 determines that the value of the skip counter is equal to or greater than the upper limit, in step S18, the control unit 14 causes the voltage conversion unit 4 to perform a discharge operation until the voltage of the power storage unit 3 becomes less than the first threshold. Then, in step S19, the control unit 14 clears the skip counter and then ends the processing shown in Figures 3 and 4. On the other hand, if the control unit 14 determines that the value of the skip counter is not equal to or greater than the upper limit, in step S17, the control unit 14 causes the voltage conversion unit 4 to perform a discharge operation until the voltage of the power storage unit 3 becomes less than the second threshold. Then, the control unit 14 ends the processing shown in Figures 3 and 4.

[0048] 5 conceptually illustrates an example of the operation of the in-vehicle control device 10. When the vehicle starts, the control unit 14 of the in-vehicle control device 10 performs a measurement process if the voltage of the power storage unit 3 is less than the determination value VJ, provided that the temperature around the power storage unit 3 is equal to or higher than the threshold temperature. As a result, the voltage of the power storage unit 3 increases within a range that does not exceed the rated voltage VR. Thereafter, the control unit 14 clears the skip counter, and when the vehicle is parked, causes the voltage conversion unit 4 to perform a discharge operation until the voltage of the power storage unit 3 becomes less than the second threshold V2.

[0049] When the vehicle starts, if the voltage of the power storage unit 3 is equal to or greater than the determination value VJ, the control unit 14 skips the measurement process and increments the skip counter by 1. If the number in the skip counter is less than the upper limit when the vehicle is parked, the control unit 14 causes the voltage conversion unit 4 to perform a discharge operation until the voltage of the power storage unit 3 becomes less than the second threshold value V2. If the number in the skip counter is equal to or greater than the upper limit when the vehicle is parked, the control unit 14 causes the voltage conversion unit 4 to perform a discharge operation until the voltage of the power storage unit 3 becomes less than the first threshold value V1.

[0050] After the discharge operation is completed, the vehicle enters a standby state until it is started. During the standby state, natural discharge occurs.

[0051] 3. Examples of Functions and Effects of the In-Vehicle Control Device 10 The in-vehicle control device 10 of the first embodiment can perform a measurement process when a measurement condition is met. The measurement condition includes a condition that the voltage of the power storage unit 3 is less than a determination value and that the temperature around the power storage unit 3 is equal to or greater than a threshold temperature. The determination value is set so that the voltage of the power storage unit 3 does not exceed the rated voltage even when the measurement process is performed when the temperature around the power storage unit 3 is equal to or greater than the threshold temperature. Therefore, the in-vehicle control device 10 can perform a measurement process so that the voltage of the power storage unit 3 does not exceed the rated voltage. Furthermore, even if the measurement condition continues not to be met, if the number of skipped times reaches or exceeds an upper limit, the in-vehicle control device 10 discharges the power storage unit 3 when the vehicle is parked until the voltage of the power storage unit 3 becomes less than the first threshold. This makes it easier for the measurement condition to be met the next time the vehicle is started, and for the measurement process to be performed. In other words, the in-vehicle control device 10 can easily prevent a measurement process from being not performed for a long period of time while suppressing unnecessary discharge.

[0052] The on-board control device 10 can set the first threshold value taking into consideration the measurement value obtained in the most recent measurement process.

[0053] The in-vehicle control device 10 can measure the internal resistance of the power storage unit 3 based on the constant current flowing through the power storage unit 3 and the change in voltage of the power storage unit 3 before and after the start of the charging operation. When a constant current flows, the voltage of the power storage unit 3 is likely to rise and exceed the rated voltage. In this regard, the in-vehicle control device 10 performs the measurement process on the condition that the voltage of the power storage unit 3 is less than the determination value, and therefore can easily prevent the voltage of the power storage unit 3 from exceeding the rated voltage when the measurement process is performed.

[0054] Even if the number of times the measurement process has been skipped when the vehicle is parked is less than the upper limit, the in-vehicle control device 10 can discharge the power storage unit 3 until the voltage of the power storage unit 3 becomes less than the second threshold. Therefore, the in-vehicle control device 10 can increase the possibility that the voltage of the power storage unit 3 will be less than the determination value when the vehicle is started, compared to when no discharge is performed. As a result, the in-vehicle control device 10 can increase the possibility that the measurement process will be performed.

[0055] When the vehicle control device 10 sets the second threshold value based on the ambient temperature of the storage unit 3 when the vehicle is parked or immediately after starting, the vehicle control device 10 can set the second threshold value based on the temperature in an environment where the vehicle's air conditioning has little effect.

[0056] <Other Embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or below-described embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or below-described embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiments may be modified as follows.

[0057] In the first embodiment described above, if the number of times measurement processing has been skipped is less than the upper limit when the vehicle is parked, the control unit 14 always causes the voltage conversion unit 4 to discharge until the voltage of the power storage unit 3 becomes less than the second threshold, but this may not be the case. For example, the control unit 14 may cause the voltage conversion unit 4 to discharge until the voltage of the power storage unit 3 becomes less than the second threshold only when the vehicle is parked after performing the measurement processing.

[0058] In the first embodiment described above, the charging section and the discharging section are configured by the same circuit (specifically, a DCDC converter), but they may be configured by separate circuits.

[0059] In the first embodiment described above, the discharge unit is configured to discharge to the power supply unit 2, but the discharge unit may be configured to discharge to a load, a discharge resistor, or the like.

[0060] In the first embodiment described above, the measurement condition is "a condition that the voltage of the power storage unit 3 is less than a predetermined determination value and the temperature around the power storage unit 3 is equal to or greater than a threshold temperature," but is not limited to this condition. For example, the measurement condition may be a condition that includes another condition in addition to "a condition that the voltage of the power storage unit 3 is less than a predetermined determination value and the temperature around the power storage unit 3 is equal to or greater than a threshold temperature," or may be "a condition that the voltage of the power storage unit 3 is less than a predetermined determination value."

[0061] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims.

[0062] REFERENCE SIGNS LIST 1...In-vehicle system 2...Power supply unit 3...Electricity storage unit 3A...Battery cell 4...Voltage conversion unit (charging unit, discharging unit) 10...In-vehicle control device 11...Current detection unit 12...Voltage detection unit 13...Temperature detection unit 14...Control unit (measurement unit, discharging control unit) 21...Cell balance circuit 21A...Cell discharge unit 22...Voltage signal line 81...First conductive path 82...Second conductive path V1...First threshold V2...Second threshold VJ...Determination value VMAX...Fully charged voltage VR...Rated voltage

Claims

1. An in-vehicle control device included in an in-vehicle system including a power supply unit, a power storage unit, a charging unit that performs a charging operation to charge the power storage unit based on power from the power supply unit, and a discharging unit that performs a discharging operation to discharge the power storage unit, the in-vehicle control device having a measurement unit that performs a measurement process, and a discharge control unit that controls the discharge unit, wherein the measurement process is a process of causing the charging unit to perform the charging operation and measuring an internal resistance of the power storage unit based on a voltage change of the power storage unit before and after the start of the charging operation, the measurement unit performs the measurement process if a measurement condition is satisfied during a measurement period from when the vehicle is in a start state to when the vehicle is in a parked state, and omits the measurement process if the measurement condition is not satisfied during the measurement period, the measurement condition includes a condition that the voltage of the power storage unit is less than a determination value, and the discharge control unit causes the discharge unit to perform the discharge operation until the voltage of the power storage unit becomes less than a first threshold that is less than the determination value, when the number of times the measurement process has been omitted when the vehicle is in the parked state is equal to or greater than an upper limit value.

2. The in-vehicle control device according to claim 1, wherein the discharge control unit sets the first threshold value based on a measurement value measured in the most recent measurement process.

3. The in-vehicle control device according to claim 1 or 2, wherein, in the measurement process, the measurement unit causes the charging unit to perform the charging operation so that a constant current flows through the storage unit, and measures the internal resistance of the storage unit based on the constant current flowing through the storage unit and a change in voltage of the storage unit before and after the start of the charging operation.

4. The vehicle-mounted control device according to claim 1 or 2, wherein the discharge control unit causes the discharge unit to perform the discharge operation until the voltage of the storage unit becomes less than a second threshold value that is greater than the first threshold value when the number of times the measurement process has been omitted is less than the upper limit value when the vehicle is in the parked state.

5. The vehicle-mounted control device according to claim 4, wherein the discharge control unit sets the second threshold value based on the temperature around the power storage unit in the parked state or immediately after the vehicle is started.

6. The vehicle-mounted control device according to claim 1 or 2, wherein the measurement conditions include a condition that the voltage of the power storage unit is less than the determination value and the temperature around the power storage unit is equal to or higher than a threshold temperature.

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