On-vehicle capacitor device

Abstract

To provide an on-vehicle capacitor device capable of enhancing accuracy of determining whether or not a capacitor has deteriorated.SOLUTION: An on-vehicle capacitor device 18 outputs power of a capacitor 19 in emergency of a main power supply 7 as backup power supply for the main power supply 7. A capacitance calculation unit 26 obtains a current flowing to the capacitor 19 during charging and an amount of voltage change of the capacitor 19 that generates in a sampling period of the current, and calculates a capacitance of the capacitor 19 on the basis of the current and the amount of voltage change. A deterioration determination unit 28 determines deterioration of the capacitor 19 on the basis of the capacitance calculated in the capacitance calculation unit 26. The deterioration determination unit 28 executes deterioration determination using a calculation result of the capacitance calculation unit 26, that satisfies the amount of voltage change is a threshold value or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an on-vehicle capacitor device. [Background technology]

[0002] Conventionally, there is known an in-vehicle power supply device capable of detecting deterioration of a power storage unit of a backup power supply in a vehicle, as disclosed in Patent Document 1. In Patent Document 1, when the capacity of the power storage unit specified based on the output voltage value detected by a voltage detection unit and the resistance value of a constant load unit is equal to or less than a certain value, the power storage unit is determined to be in a deteriorated state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-164323 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in this type of vehicle-mounted power supply device, there has been a need to determine the deterioration state of the power storage unit of the backup power supply with greater accuracy. An object of the present disclosure is to provide an in-vehicle capacitor device capable of improving the accuracy of determining whether or not a capacitor has deteriorated. [Means for solving the problem]

[0005] The on-board capacitor device that solves the above problem has a capacitor that is charged by a main power supply mounted on the vehicle when the main power supply voltage supplied from the main power supply is equal to or higher than a specified value, and outputs the power of the capacitor as a backup power supply for the main power supply in the event of an emergency with the main power supply.The device is equipped with a capacity calculation unit that calculates the current flowing through the capacitor during charging and the amount of voltage change in the capacitor that occurs during a sampling period of the current, and calculates the capacitance of the capacitor based on the current and the amount of voltage change, and a deterioration determination unit that determines deterioration of the capacitor based on the capacity calculated by the capacity calculation unit, and the deterioration determination unit performs deterioration determination using a calculation result of the capacity calculation unit that satisfies that the amount of voltage change is equal to or higher than a threshold value. Effect of the Invention

[0006] The present disclosure can improve the accuracy of determining whether or not a capacitor has deteriorated. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a configuration diagram of an on-vehicle capacitor device according to an embodiment. [Diagram 2] FIG. 2 is a waveform diagram of the capacitor current and the capacitor voltage. [Diagram 3] FIG. 3 is a waveform diagram of the main power supply voltage. [Figure 4] FIG. 4 is a waveform diagram of the main power supply voltage, the capacitor voltage, and the capacitor current. [Diagram 5] FIG. 5 is a waveform diagram of the main power supply voltage, the capacitor voltage, and the capacitor current. [Figure 6] FIG. 6 is a table showing the relationship between drive cycles and capacity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] First, the embodiments of the present disclosure will be listed and described. [1] The on-board capacitor device of the present disclosure has a capacitor that is charged by a main power supply mounted on a vehicle when the main power supply voltage supplied from the main power supply is equal to or higher than a specified value, and outputs the power of the capacitor as a backup power supply for the main power supply in the event of an emergency with the main power supply. The on-board capacitor device includes a capacity calculation unit that calculates a current flowing through the capacitor during charging and an amount of voltage change in the capacitor that occurs during a sampling period of the current, and calculates a capacity of the capacitor based on the current and the amount of voltage change, and a deterioration determination unit that determines deterioration of the capacitor based on the capacity calculated by the capacity calculation unit, and the deterioration determination unit performs deterioration determination using a calculation result of the capacity calculation unit that satisfies that the amount of voltage change is equal to or higher than a threshold value.

[0009] According to this configuration, since the charging of the capacitor is performed under the condition that the main power supply voltage is equal to or greater than a specified value, when the main power supply voltage falls below the specified value, the charging is forcibly stopped. In this case, the charging ends midway, and a sufficient number of samplings of the capacitor current cannot be secured. Therefore, the capacitance of the capacitor cannot be obtained with high accuracy, and the accuracy of the deterioration determination is low. However, when the charging of the capacitor is forcibly ended, the charging time is not sufficient, so the voltage change amount should be small. In view of this point, the deterioration determination is performed using the calculation result of the capacitance calculation unit that satisfies that the voltage change amount is equal to or greater than a threshold value. Therefore, it is possible to improve the accuracy of the determination of the deterioration of the capacitor.

[0010] [2] In the above [1], the degradation determination unit executes degradation determination using the calculation result of the capacitance calculation unit that satisfies that the sampling time of the current is equal to or longer than a threshold. According to this configuration, if the sampling time required to sample the current is equal to or longer than a threshold, a sufficient number of current values ​​are obtained. This further contributes to correctly calculating the capacitance of the capacitor. Therefore, it further contributes to improving the accuracy of determining whether the capacitor has deteriorated.

[0011] [3] In the above [1] or [2], the capacity calculation unit discards the calculation result if the calculation does not satisfy the condition, and the deterioration determination unit performs deterioration determination using a previous calculation result if the capacity calculation unit discards the calculation result. With this configuration, even if the calculation result by the capacity calculation unit is discarded, it is possible to continue the deterioration determination process using the calculation result that is assumed to be closest at that time.

[0012] [4] In any one of [1] to [3] above, the deterioration determination unit calculates an average value of the multiple capacitances calculated by the capacitance calculation unit each time charging is performed, and performs deterioration determination using the average value. With this configuration, even if one capacitance value of the capacitor fluctuates suddenly, the effect of the one value that fluctuates suddenly can be reduced by taking the average of the capacitances. This further contributes to improving the accuracy of determining whether or not the capacitor has deteriorated.

[0013] [5] In any one of [1] to [4] above, the capacity calculation unit obtains the current and the voltage change amount while avoiding the transient region at the start of charging. This configuration makes it possible to obtain the voltage change amount during a period in which the voltage change is stable, which contributes to obtaining an appropriate voltage change amount. This further contributes to improving the accuracy of determining whether or not the capacitor has deteriorated.

[0014] [6] In any one of the above [1] to [5], the capacitance calculation unit calculates the capacitance by calculating a total amount of current flowing through the capacitor during the sampling period and dividing the total amount of current by the amount of change in voltage. With this configuration, it is possible to accurately calculate the capacitance of the capacitor using a simple calculation formula.

[0015] [7] In any one of the above [1] to [6], the capacitor supplies power to the backup target device, and the backup target device includes at least one of a driving system electrical component related to the driving of the vehicle and a locking / unlocking system electrical component related to the locking / unlocking of the doors of the vehicle. With this configuration, it is possible to stably supply backup power from the capacitor to the electrical components related to stopping the vehicle or getting off. This contributes to ensuring safety when driving the vehicle.

[0016] [8] In any one of [1] to [7] above, the vehicle equipped with the capacitor has an engine as a driving source, and the main power supply voltage fluctuates due to cranking at the start of the engine. According to this configuration, when the main power supply voltage fluctuates due to engine cranking, the main power supply voltage may fall below a specified value and charging of the capacitor may be forcibly terminated. However, when charging of the capacitor is forcibly terminated, sufficient parameters for deterioration determination cannot be obtained, and deterioration determination is not performed with the capacity calculated at that time. Therefore, it is possible to accurately determine the deterioration of the capacitor even in a vehicle in which charging of the capacitor is forcibly terminated by cranking.

[0017] [Details of the embodiment of the present disclosure] Specific examples of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope of the claims. In each drawing, for convenience of explanation, some of the configurations may be exaggerated or simplified. In addition, the dimensional ratios of each part may differ from the actual ones.

[0018] (Vehicle System 1) As shown in Fig. 1, the vehicle 2 includes a vehicle system 1 that controls the operation of the vehicle 2. The vehicle system 1 includes, for example, a system control unit 3, an engine 4, and on-board equipment 5. The system control unit 3 controls the engine 4 and on-board equipment 5 based on signals input from sensors and switches (not shown) mounted on the vehicle 2. Examples of the vehicle 2 include an engine vehicle, a hybrid vehicle, and a plug-in hybrid vehicle. Note that the vehicle 2 is not limited to one having the engine 4, and may be, for example, an electric vehicle, a fuel cell vehicle, or a hydrogen vehicle.

[0019] (Power supply for vehicle system 1) As shown in Fig. 1, a vehicle 2 has a main power supply 7 used as a power supply for a vehicle system 1 in normal times, and a backup power supply 8 used as a power supply for the vehicle system 1 in an emergency. The main power supply 7 is, for example, a vehicle battery. The backup power supply 8 supplies power to a specific in-vehicle device 5 (backup target device 9 in this example) in an emergency, for example, when an abnormality occurs in the main power supply 7 and it becomes impossible to supply power to the in-vehicle device 5. Examples of abnormalities occurring in the main power supply 7 include a breakdown of the main power supply 7 and a break in the wiring provided in the main power supply 7.

[0020] (In-vehicle equipment 5) 1, the in-vehicle equipment 5 has in-vehicle electrical equipment 10 provided for each of various functions of the vehicle 2. Examples of the in-vehicle electrical equipment 10 include an engine device, a transmission device, a power window device, a door mirror device, an air conditioner device, a power steering device, a meter device, an ETC device, a seat device, a lighting device, a navigation device, an audio device, and a wiper device.

[0021] The backup target devices 9 normally operate on the power of the main power supply 7, but operate on the power of the backup power supply 8 in the event of an emergency with the main power supply 7. The backup target devices 9 include, for example, a driving system electrical component 11 related to the driving of the vehicle 2, and a locking / unlocking system electrical component 12 related to the locking / unlocking of the doors of the vehicle 2. The driving system electrical component 11 is, for example, a brake device. The locking / unlocking system electrical component 12 is, for example, a keyless entry device, a door lock device, etc.

[0022] (Backup power supply 8) 1, backup power supply 8 has a first port 14 connected to system control unit 3, a second port 15 connected to main power supply 7, and a third port 16 connected to backup target device 9. Backup power supply 8 is charged by power from main power supply 7, for example, when the power state of vehicle 2 is turned on (e.g., ignition on). Backup power supply 8 supplies power to backup target device 9, for example, when vehicle system 1 detects an abnormality in main power supply 7.

[0023] (In-vehicle capacitor device 18) 1, the backup power supply 8 has an in-vehicle capacitor device 18 that performs charging and discharging using a capacitor 19 as a medium. The in-vehicle capacitor device 18 has a power supply control unit 20 that controls the operation of the in-vehicle capacitor device 18, and a charge / discharge circuit unit 21 that charges and discharges the capacitor 19. The in-vehicle capacitor device 18 may be configured independently of the vehicle system 1, or may be configured as a part of the vehicle system 1.

[0024] The power supply control unit 20 includes a charge / discharge control unit 22 that controls the charging and discharging operations of the capacitor 19. The charge / discharge control unit 22 receives, for example, a command related to the operation of the backup power supply 8 from the system control unit 3 via the first port 14, and controls the charge / discharge circuit unit 21 based on the received command.

[0025] The charge / discharge circuit unit 21 is connected to the main power supply 7 via the second port 15, and is connected to the backup target device 9 via the third port 16. When charging the capacitor 19, the charge / discharge circuit unit 21 outputs the power acquired from the main power supply 7 via the second port 15 to the capacitor 19. When the capacitor 19 operates as a backup power supply, the charge / discharge circuit unit 21 outputs the power of the capacitor 19 from the third port 16 to the backup target device 9.

[0026] When the system control unit 3 receives a power-on signal (e.g., an ignition-on signal) of the vehicle power supply, the system control unit 3 outputs a charge start request to the power control unit 20. When the power control unit 20 receives a charge start request from the system control unit 3, the charge / discharge control unit 22 causes the charge / discharge circuit unit 21 to charge the capacitor 19. In this manner, the charge / discharge circuit unit 21 executes charging when the vehicle 2 is in a power-on state. In this example, when the vehicle 2 is in a power-on state, the charge / discharge circuit unit 21 inputs power from the main power supply 7 from the second port 15 and sends this power to the capacitor 19, thereby charging the capacitor 19. It is preferable that the charge / discharge control unit 22 continues charging until the voltage of the capacitor 19 (hereinafter referred to as the capacitor voltage Vc) becomes equal to or greater than a predetermined value or until the charging time becomes equal to or greater than a predetermined time.

[0027] The system control unit 3 constantly monitors the voltage of the main power supply 7 while the vehicle power supply is turned on (for example, the ignition is on). When the system control unit 3 detects that an abnormality has occurred in the main power supply 7, it outputs a backup start request to the power supply control unit 20. When the power supply control unit 20 receives a backup start request from the system control unit 3, the charge / discharge control unit 22 outputs the power of the capacitor 19 to the backup target device 9 via the charge / discharge circuit unit 21. Therefore, even if an abnormality occurs in the main power supply 7, it is possible to continue operating the backup target device 9 using the power of the capacitor 19.

[0028] It is preferable that capacitor 19 is discharged until a constant voltage is reached when the vehicle power supply is turned off. For example, when the system control unit 3 receives a vehicle power supply off signal (e.g., an ignition off signal), it outputs a discharge start request to power supply control unit 20. When power supply control unit 20 receives a discharge start request from system control unit 3, charge / discharge control unit 22 causes charge / discharge circuit unit 21 to discharge capacitor 19. Specifically, charge / discharge circuit unit 21 discharges the power of capacitor 19 via charge / discharge circuit unit 21, thereby lowering the voltage of capacitor 19 to a constant value. This makes it possible to keep the voltage of capacitor 19 at a constant value.

[0029] (Deterioration determination of capacitor 19) 1, the in-vehicle capacitor device 18 has a function (capacitor deterioration determination function) for executing deterioration determination of the capacitor 19. The capacitor deterioration determination function of this example calculates the capacitance C of the capacitor 19 based on, for example, the current Ic flowing through the capacitor 19 and the capacitor voltage Vc when the capacitor 19 is charged. Then, when the capacitance C is less than a predetermined value, it is determined that the capacitor 19 has deteriorated.

[0030] The charge / discharge circuit unit 21 has a current detection unit 24 that detects a current Ic flowing through the capacitor 19, and a voltage detection unit 25 that detects a capacitor voltage Vc. The current detection unit 24 outputs the detected value of the current Ic to the power supply control unit 20. The voltage detection unit 25 outputs the detected value of the capacitor voltage Vc to the power supply control unit 20.

[0031] The in-vehicle capacitor device 18 includes a capacitance calculation unit 26 that calculates the capacitance C of the capacitor 19. The capacitance calculation unit 26 is provided in the power supply control unit 20. The capacitance calculation unit 26 calculates the capacitance C of the capacitor 19 based on the current Ic detected by the current detection unit 24 and the capacitor voltage Vc detected by the voltage detection unit 25. It is preferable that the capacitance calculation unit 26 writes and stores the calculated value of the capacitance C in a memory 27 of the backup power supply 8. The memory 27 is provided in, for example, the power supply control unit 20.

[0032] It is preferable that the capacity calculation unit 26 executes the capacity calculation once in one drive cycle. A drive cycle refers to, for example, one cycle from when the vehicle power supply is turned on to when it is turned off again.

[0033] 2, capacitance calculation unit 26 obtains current Ic flowing through capacitor 19 during charging and voltage change ΔV of capacitor 19 occurring during a sampling period of current Ic, and calculates capacitance C of capacitor 19 based on current Ic and voltage change ΔV. In this example, voltage change ΔV is the difference between a first voltage V1, which is the value when the voltage stabilizes after charging begins, and a second voltage V2, which is the value when current Ic has been sufficiently sampled.

[0034] 1, the in-vehicle capacitor device 18 includes a deterioration determination unit 28 that determines deterioration of the capacitor 19 based on the capacitance C calculated by the capacitance calculation unit 26. The deterioration determination unit 28 is provided in the power supply control unit 20. The deterioration determination unit 28 compares the capacitance C calculated by the capacitance calculation unit 26 with a predetermined value, and determines that no deterioration has occurred in the capacitor 19 if the capacitance C is equal to or greater than the predetermined value. On the other hand, the deterioration determination unit 28 determines that the capacitor 19 has deteriorated if the capacitance C of the capacitor 19 is less than the predetermined value.

[0035] 2, when the voltage change amount ΔV is less than the threshold, the capacity calculation unit 26 discards the calculation result performed at that time. In this way, the deterioration determination unit 28 performs deterioration determination using the calculation result of the capacity calculation unit 26 that satisfies that the voltage change amount ΔV is equal to or greater than the threshold. The threshold value of the voltage change amount ΔV is preferably a value that ensures a sufficient number of samplings of the current Ic, for example. When the capacity calculation unit 26 discards the calculation result, the deterioration determination unit 28 preferably performs deterioration determination using the past calculation result.

[0036] Next, the operation of the on-vehicle capacitor device 18 of this embodiment will be described. (Calculating the capacitance of capacitor 19) As shown in Fig. 2, when the ignition of the vehicle power supply is turned on, charging of the capacitor 19 is started. In this example, the charge / discharge control unit 22 starts charging the capacitor 19 with the voltage of the main power supply 7 when, for example, an ignition-on signal (not shown) is input from the vehicle system 1 (specifically, the engine switch of the vehicle 2). When charging is started, a current Ic flows from the main power supply 7 to the capacitor 19, and the capacitor voltage Vc rises. Note that, in order to avoid early deterioration, it is preferable to leave a certain amount of capacitance C of the capacitor 19 rather than completely emptying it before charging starts.

[0037] After the transient region Ta has elapsed since the start of charging, the capacitance calculation unit 26 starts sampling the current Ic and acquires the capacitor voltage Vc (herein referred to as the first voltage V1) at the start of sampling. That is, the capacitance calculation unit 26 acquires the current Ic and the capacitor voltage Vc while avoiding the transient region Ta in which the capacitor voltage Vc is not stable. This is to acquire the first voltage V1 of a stable value.

[0038] The capacitance calculation unit 26 samples the current Ic at intervals of time ts during a predetermined sampling period. The sampling period refers to the period from the start of sampling the current Ic to the end of sampling. The sampling time Tc of the current Ic is preferably a value obtained by multiplying the sampling interval time ts by the number of times the current Ic is sampled. In this example, the capacitance calculation unit 26 increments the sampled current Ic and divides the incremented value by the number of times the current Ic is sampled to calculate the average value Ik of the current Ic.

[0039] Furthermore, the capacitance calculation unit 26 obtains the capacitor voltage Vc (here, referred to as the second voltage V2) at the point in time when a sufficient number of samples of the current Ic have been obtained. The second voltage V2 is, for example, the capacitor voltage Vc at the point in time when a sufficient number of samples of the current Ic have been obtained.

[0040] The capacitance calculation unit 26 uses the current Ic (average value Ik in this example), the sampling time Tc, the first voltage V1, and the second voltage V2 to calculate the capacitance C according to the following formula (1). C = (Ic × Tc) / (V2 - V1) … (1) The capacity calculation unit 26 writes the calculated value of the capacity C to the memory 27. The capacity C written to the memory 27 is held in the memory 27 even when the vehicle power supply is turned off with the ignition turned off.

[0041] Deterioration determination unit 28 determines whether capacitor 19 has deteriorated based on capacitance C calculated by capacitance calculation unit 26. Deterioration determination unit 28 determines that capacitor 19 has deteriorated when capacitance C is less than a predetermined value. When deterioration determination unit 28 determines that capacitor 19 has deteriorated, it notifies the user by, for example, displaying a message on the instrument panel at the driver's seat or using a speaker in the vehicle. This notifies the user that capacitor 19 is in a deteriorated state.

[0042] In this example, the first voltage V1 is acquired while avoiding the transient region Ta, so that it is possible to acquire an accurate voltage change amount ΔV. In addition, the number of times the current Ic is sampled is sufficient, so that it is possible to accurately calculate "Ic×Tc" in equation (1). Furthermore, the second voltage V2 is acquired after a sufficient charging time, which further contributes to ensuring an accurate voltage change amount ΔV.

[0043] (Phenomenon when starting the engine) As shown in Fig. 3, when an ignition-on operation is performed, starting of the engine 4 is initiated. Starting of the engine 4 is initiated, for example, by cranking which rotates a crankshaft (not shown). During cranking, the voltage of the main power supply 7 is supplied to the engine 4, so that the main power supply voltage Vb supplied from the main power supply 7 to the capacitor 19 fluctuates. Specifically, the main power supply voltage Vb has a waveform which is significantly reduced by cranking.

[0044] Incidentally, when the voltage of the main power supply 7 is sufficiently high, even if a voltage drop occurs due to cranking, the main power supply voltage Vb supplied from the main power supply 7 to the capacitor 19 does not fall below a specified value Vb1. The specified value Vb1 is a main power supply failure determination threshold that serves as a criterion for determining whether the main power supply voltage Vb is a sufficient value for charging the capacitor 19. Therefore, the charging of the capacitor 19 that started when the ignition was turned on is not terminated midway but is continued. In other words, the charging of the capacitor 19 that has started once is not forcibly terminated midway by cranking.

[0045] (Capacity calculation issues) Fig. 4 shows a waveform of the main power supply voltage Vb (main power supply voltage waveform S1), a waveform of the capacitor voltage Vc (capacitor voltage waveform S2), and a waveform of the current Ic of the capacitor 19 (capacitor current waveform S3) when the main power supply voltage Vb drops significantly due to cranking, etc. In Fig. 4, the main power supply voltage waveform S1 is shown in the upper part, the capacitor voltage waveform S2 is shown in the middle part, and the capacitor current waveform S3 is shown in the lower part.

[0046] As shown by the main power supply voltage waveform S1 in FIG. 4, if the battery is used in a low-temperature environment or if the main power supply 7 is deteriorated, the main power supply voltage Vb drops significantly during cranking. Therefore, even if charging starts once, the main power supply voltage Vb falls below the specified value Vb1, and charging ends immediately. In this case, as shown by the capacitor voltage waveform S2 in FIG. 4, the charging time is very short, and the voltage change amount ΔV is small. Therefore, the capacitance C cannot be calculated accurately.

[0047] (Advantages of the in-vehicle capacitor device 18 of this embodiment) In this example, as shown in Fig. 4, if the amount of voltage change ΔV is not equal to or greater than the threshold, the calculation result at that time does not determine whether or not the capacitor 19 has deteriorated. Therefore, if charging of the capacitor 19 is started once but then immediately stopped, the amount of voltage change ΔV is not equal to or greater than the threshold, and therefore the deterioration determination is not performed based on the capacitance C calculated at that time. Therefore, the deterioration determination is not performed based on the capacitance C that is assumed to have a large calculation error.

[0048] When it is not satisfied that the voltage change amount ΔV is equal to or greater than the threshold, deterioration determination unit 28 performs deterioration determination using the value of capacitance C calculated in the past as the current capacitance C of capacitor 19. Specifically, when it is not satisfied that the voltage change amount ΔV is equal to or greater than the threshold, deterioration determination unit 28 performs deterioration determination using the most recent data of capacitance C stored in memory 27 as the current capacitance C of capacitor 19. Thus, it becomes possible to perform deterioration determination using a capacitance C value close to the current value.

[0049] Furthermore, it is preferable that the deterioration determination unit 28 performs the deterioration determination using the calculation result of the capacity calculation unit 26 that satisfies that the sampling time Tc of the current Ic is equal to or greater than the threshold value. That is, when the sampling time Tc of the current Ic is insufficient, it is preferable that the deterioration determination unit 28 does not perform the deterioration determination using the calculation result calculated at that time. Specifically, it is preferable that the capacity calculation unit 26 checks whether the sampling time Tc of the current Ic is equal to or greater than the threshold value, and when the sampling time Tc is not equal to or greater than the threshold value, it discards the calculation result performed at that time. This also contributes to ensuring the accuracy of the deterioration determination of the capacitor 19.

[0050] 4, the capacitance calculation unit 26 may stop the capacitance calculation when the current Ic flowing through the capacitor 19 becomes less than the capacitance calculation end determination threshold Ic1. When the current Ic becomes less than the capacitance calculation end determination threshold Ic1 and the capacitance calculation is stopped, the capacitance C is not recalculated in that drive cycle. This also contributes to ensuring the accuracy of the deterioration determination of the capacitor 19.

[0051] Furthermore, as shown in Fig. 5, when the main power supply voltage Vb drops due to cranking or the like, even if the main power supply voltage Vb does not fall below the specified value Vb1, if the current Ic falls below the capacity calculation end determination threshold Ic1, the capacity calculation is stopped. Therefore, even in an unstable state where the main power supply voltage Vb has not dropped significantly but the current Ic falls below the capacity calculation end determination threshold Ic1, the capacity calculation is stopped. This further contributes to ensuring the accuracy of the capacity calculation.

[0052] (Averaging of capacitance C) As shown in Fig. 6, the deterioration determination unit 28 may obtain an average value Cave of the multiple capacities C calculated by the capacity calculation unit 26 each time charging is performed, and perform deterioration determination using the average value Cave. Specifically, the average value Cave of the capacities C (C1, C2, ... Cn) calculated in each drive cycle is calculated. In this case, even if the capacitance C is suddenly calculated as an abnormal value, it is possible to reduce the influence of this abnormal value by taking the average of the capacitances C. This further contributes to ensuring the accuracy of the deterioration determination of the capacitor 19.

[0053] (Effects of the embodiment) According to the configuration of the above embodiment, the following effects can be obtained. (1) The in-vehicle capacitor device 18 has a capacitor 19 that is charged by the in-vehicle main power supply 7 when the main power supply voltage Vb supplied from the in-vehicle main power supply 7 is equal to or higher than a specified value Vb1. The in-vehicle capacitor device 18 outputs the power of the capacitor 19 as a backup power supply for the main power supply 7 in the event of an emergency of the main power supply 7. The capacitance calculation unit 26 included in the in-vehicle capacitor device 18 obtains the current Ic flowing through the capacitor 19 during charging and the voltage change amount ΔV of the capacitor 19 occurring during a sampling period of the current Ic, and calculates the capacitance C of the capacitor 19 based on the current Ic and the voltage change amount ΔV. The deterioration determination unit 28 included in the in-vehicle capacitor device 18 determines the deterioration of the capacitor 19 based on the capacitance C calculated by the capacitance calculation unit 26. The deterioration determination unit 28 executes the deterioration determination using the calculation result of the capacitance calculation unit 26 that satisfies that the voltage change amount ΔV is equal to or higher than a threshold value.

[0054] According to this configuration, since the charging of the capacitor 19 is performed under the condition that the main power supply voltage Vb is equal to or greater than the specified value Vb1, when the main power supply voltage Vb falls below the specified value Vb1, the charging is forcibly stopped. In this case, the charging ends midway, and a sufficient number of samples of the current Ic of the capacitor 19 cannot be secured. Therefore, the capacitance C of the capacitor 19 cannot be obtained with high accuracy, and the accuracy of the deterioration determination is low. However, when the charging of the capacitor 19 is forcibly ended, the charging time is not sufficient, so the voltage change amount ΔV should be small. In view of this point, the deterioration determination is performed using the calculation result of the capacitance calculation unit 26 that satisfies that the voltage change amount ΔV is equal to or greater than the threshold value. Therefore, the accuracy of the determination of the deterioration of the capacitor 19 can be improved.

[0055] (2) The deterioration determination unit 28 performs deterioration determination using the calculation result of the capacitance calculation unit 26 that satisfies that the sampling time Tc of the current Ic is equal to or greater than the threshold value. According to this configuration, if the sampling time Tc required to sample the current Ic is equal to or greater than the threshold value, a sufficient number of values ​​of the current Ic are obtained. This contributes further to correctly calculating the capacitance C of the capacitor 19. Therefore, it contributes further to improving the accuracy of determining whether or not the capacitor 19 has deteriorated.

[0056] (3) If the capacity calculation unit 26 does not satisfy the conditions, it discards the calculation result. If the capacity calculation unit 26 discards the calculation result, the deterioration determination unit 28 executes the deterioration determination using the past calculation result. With this configuration, even if the calculation result by the capacity calculation unit 26 is discarded, it is possible to continue the deterioration determination process using the calculation result that is assumed to be closest at that time.

[0057] (4) The deterioration determination unit 28 calculates the average value Cave of the multiple capacitances C calculated by the capacitance calculation unit 26 each time charging is performed, and performs deterioration determination using the average value Cave. With this configuration, even if one value of the capacitance C of the capacitor 19 suddenly changes, it is possible to reduce the influence of the one value that suddenly changes by taking the average of the capacitances C. This further contributes to improving the accuracy of determining whether or not the capacitor 19 has deteriorated.

[0058] (5) The capacity calculation unit 26 acquires the current Ic and the voltage change amount ΔV while avoiding the transient region Ta at the start of charging. This configuration makes it possible to obtain the voltage change amount ΔV during a period in which the voltage change is stable, which contributes to acquiring an appropriate voltage change amount ΔV. This further contributes to improving the accuracy of determining whether or not the capacitor 19 has deteriorated.

[0059] (6) The capacitance calculation unit 26 obtains the total amount of current "Ic×Tc" flowing through the capacitor 19 during the sampling period, and divides the total amount of current "Ic×Tc" by the amount of voltage change ΔV to calculate the capacitance C. With this configuration, the capacitance C of the capacitor 19 can be calculated with high accuracy using a simple formula.

[0060] (7) Capacitor 19 supplies power to backup target device 9. Backup target device 9 includes at least one of driving system electrical equipment 11 related to driving of vehicle 2 and locking / unlocking system electrical equipment 12 related to locking / unlocking the doors of vehicle 2. This configuration enables stable supply of backup power from capacitor 19 to electrical equipment related to stopping driving of vehicle 2 and disembarking from the vehicle. This contributes to ensuring safety when driving the vehicle.

[0061] (8) The vehicle 2 equipped with the capacitor 19 has the engine 4 as a drive source for traveling. The main power supply voltage Vb fluctuates due to cranking at the start of the engine 4. According to this configuration, when the main power supply voltage Vb fluctuates due to cranking of the engine 4, the main power supply voltage Vb may become less than the specified value Vb1, and the charging of the capacitor 19 may be forcibly terminated. However, when the charging of the capacitor 19 is forcibly terminated, sufficient parameters for deterioration determination cannot be obtained, and therefore the deterioration determination is not performed with the capacitance C calculated at that time. Therefore, even in the vehicle 2 in which the charging of the capacitor 19 is forcibly terminated by cranking, the deterioration of the capacitor 19 can be accurately determined.

[0062] [Other embodiments] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0063] The conditions for calculating the capacity C are not limited to the voltage change ΔV being equal to or greater than a threshold, the sampling time Tc of the current Ic being equal to or greater than a threshold, etc. For example, the conditions may include the number of samples of the current Ic being equal to or greater than a threshold, the first voltage V1 being equal to or greater than a threshold, the second voltage V2 being equal to or greater than a threshold, etc.

[0064] The method of not accepting the calculation result when the conditions for calculating the capacity C are not satisfied is not limited to the method in which the capacity calculation unit 26 discards the calculation result. For example, a method in which the degradation determination unit 28 does not obtain the calculation result, or a method in which the capacity calculation unit 26 ends the calculation midway may be adopted.

[0065] The power supply control unit 20 may be included in the system control unit 3. The backup target device 9 may be changed to a device other than that in the embodiment. The on-vehicle capacitor device 18 is not limited to being mounted on a vehicle 2 that uses an engine 4 as a drive source, and may be used in a vehicle 2 that uses a drive source other than the engine 4.

[0066] Although the present disclosure has been described with reference to the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure. [Explanation of symbols]

[0067] 1 Vehicle Systems 2 Vehicles 3 System Control Unit 4 Engine 5 In-vehicle equipment 7 Main power 8. Backup Power 9 Backup target devices 10. Automotive electrical equipment 11. Electrical equipment for driving 12 Electrical equipment for locking and unlocking 14 First Port 15 Second Port 16 Third Port 18. Capacitor device for automobiles 19 Capacitor 20 Power supply control unit 21 Charge / discharge circuit section 22 Charge / discharge control unit 24 Current detection section 25 Voltage detection section 26 Capacity calculation section 27 Memory 28 Deterioration determination section C capacity ΔV Voltage change amount IC current Ik Average S1 Mains voltage waveform S2 Capacitor voltage waveform S3 Capacitor current waveform Ta transient region Tc Sampling Time ts Time V1 First voltage V2 Second voltage Vb Main power supply voltage Vc Capacitor voltage Vb1 Default value Ic1 Capacity calculation end determination threshold Cave average value

Claims

1. 1. An on-vehicle capacitor device comprising: a capacitor that is charged by a main power supply mounted on a vehicle when a main power supply voltage supplied from the main power supply is equal to or higher than a specified value; and in the event of an emergency with the main power supply, the on-vehicle capacitor device outputs electric power of the capacitor as a backup power supply for the main power supply, a capacitance calculation unit that calculates a current flowing through the capacitor during charging and a voltage change amount of the capacitor that occurs during a sampling period of the current, and calculates a capacitance of the capacitor based on the current and the voltage change amount; a degradation determination unit that determines degradation of the capacitor based on the capacitance calculated by the capacitance calculation unit, The degradation determination unit performs degradation determination using a calculation result of the capacitance calculation unit that satisfies that the voltage change amount is equal to or greater than a threshold value.

2. 2. The on-board capacitor device according to claim 1, wherein the deterioration determining unit performs the deterioration determination using a calculation result of the capacitance calculating unit that satisfies that the current sampling time is equal to or longer than a threshold value.

3. The capacity calculation unit discards the calculation result when the condition is not satisfied, 2. The on-board capacitor device according to claim 1, wherein the deterioration determining unit performs the deterioration determination using a past calculation result when the capacitance calculating unit discards the calculation result.

4. 2. The on-board capacitor device according to claim 1, wherein the deterioration determining unit calculates an average value of the plurality of capacitances calculated by the capacitance calculating unit each time charging is performed, and performs the deterioration determination using the average value.

5. The in-vehicle capacitor device according to claim 1 , wherein the capacitance calculation unit acquires the current and the voltage change amount while avoiding a transient region at the start of charging.

6. 2. The on-vehicle capacitor device according to claim 1, wherein the capacitance calculation unit calculates the capacitance by determining a total amount of current flowing through the capacitor during the sampling period and dividing the total amount of current by the amount of voltage change.

7. The capacitor supplies power to a device to be backed up; 2. The on-vehicle capacitor device according to claim 1, wherein the backup target device includes at least one of a driving system electrical component related to driving of the vehicle and a locking / unlocking system electrical component related to locking / unlocking of doors of the vehicle.

8. The vehicle on which the capacitor is mounted has an engine as a driving source, 2. The in-vehicle capacitor device according to claim 1, wherein the main power supply voltage fluctuates due to cranking at the time of starting the engine.

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