On-vehicle capacitor device

Abstract

An on-vehicle capacitor device (18) outputs the power of a capacitor (19) as a backup power supply for a main power supply (7) in an emergency of the main power supply (7). A capacitance computation unit (26) calculates or acquires a current that flows through the capacitor (19) during charging and a voltage change amount of the capacitor (19) that occurs during a current sampling period, and computes the capacitance of the capacitor (19) on the basis of the current and the voltage change amount. A deterioration determination unit (28) determines the deterioration of the capacitor (19) on the basis of the capacitance that has been computed by the capacitance computation unit (26). The deterioration determination unit (28) uses the computation result of the capacitance computation unit (26) in which the voltage change amount is greater than or equal to a threshold value to execute a deterioration determination.

Description

In-vehicle capacitor device

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

[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, which is determined 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.

[0003] Japanese Patent Application Laid-Open No. 2018-164323

[0004] However, in this type of in-vehicle power supply device, there is a need to more accurately determine the degradation state of the power storage unit of the backup power supply. An object of the present disclosure is to provide an in-vehicle capacitor device that can improve the accuracy of determining whether or not the capacitor has deteriorated.

[0005] The on-board capacitor device that solves the above problem 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 source for the main power supply in an emergency of the main power supply.The on-board capacitor device includes: a capacity calculation unit that calculates or acquires 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 degradation determination unit that determines degradation of the capacitor based on the capacity calculated by the capacity calculation unit, and the degradation determination unit performs degradation determination using the calculation result of the capacity calculation unit that satisfies that the amount of voltage change is equal to or higher than a threshold value.

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

[0007] Fig. 1 is a configuration diagram of an on-board capacitor device according to one embodiment. Fig. 2 is a waveform diagram of a capacitor current and a capacitor voltage. Fig. 3 is a waveform diagram of a main power supply voltage. Fig. 4 is a waveform diagram of a main power supply voltage, a capacitor voltage, and a capacitor current. Fig. 5 is a waveform diagram of a main power supply voltage, a capacitor voltage, and a capacitor current. Fig. 6 is a table showing the relationship between drive cycles and capacitance.

[0008] First, embodiments of the present disclosure will be described below. [1] An on-vehicle capacitor device according to the present disclosure includes a capacitor that is charged by an on-vehicle main power supply when the main power supply voltage supplied from the main power supply is equal to or greater than a specified value, and outputs the power of the capacitor as a backup power source for the main power supply in the event of an emergency, the on-vehicle capacitor device including: a capacitance calculation unit that calculates or acquires 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; and a degradation determination unit that determines degradation of the capacitor based on the capacitance calculated by the capacitance calculation unit, the degradation determination unit performing 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.

[0009] According to this configuration, the capacitor is charged only when the main power supply voltage is equal to or greater than a specified value. Therefore, if the main power supply voltage drops below the specified value, charging is forcibly stopped. In this case, charging is terminated prematurely, and a sufficient number of capacitor current samples cannot be obtained. This prevents accurate calculation or acquisition of the capacitor's capacitance, resulting in poor degradation assessment accuracy. However, if the capacitor charging is forcibly terminated, the amount of voltage change should be small because sufficient charging time was not provided. Focusing on this point, degradation assessment is performed using the calculation results of the capacitance calculation unit that satisfy the requirement that the amount of voltage change be equal to or greater than a threshold value. This improves the accuracy of capacitor degradation assessment.

[0010] [2] In the above [1], the degradation determination unit performs degradation determination using the calculation result of the capacitance calculation unit that satisfies that the current sampling time is equal to or greater than a threshold. With this configuration, if the sampling time required to sample the current is equal to or greater than a threshold, a sufficient number of current values ​​are obtained. This further contributes to accurate calculation of the capacitance of the capacitor. Therefore, it further contributes to improving the accuracy of determining whether or not 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 of the above [1] to [3], the degradation determination unit calculates or obtains an average value of the multiple capacitances calculated by the capacitance calculation unit each time charging is performed, and performs degradation determination using the average value. With this configuration, even if a single capacitance value of the capacitor suddenly fluctuates, taking the average of the capacitances makes it possible to minimize the influence of the sudden fluctuation in the single value. This further contributes to improving the accuracy of determining whether or not the capacitor has deteriorated.

[0013] [5] In any of the above [1] to [4], the capacity calculation unit acquires the current and the voltage change amount while avoiding the transient region at the start of charging. This configuration allows the voltage change amount to be calculated or acquired during a period when the voltage change is stable, contributing 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 or acquires a total amount of current flowing through the capacitor during the sampling period, and calculates the capacitance by dividing the total amount of current by the amount of voltage change. 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 [1] to [6] above, the capacitor supplies power to backup target devices, and the backup target devices include at least one of a driving system electrical component related to vehicle driving and a locking / unlocking system electrical component related to locking / unlocking the vehicle doors. This configuration enables the capacitor to stably supply backup power to electrical components related to stopping the vehicle or getting out of the vehicle, thereby contributing to ensuring safety during vehicle driving.

[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 when the engine is started. With this configuration, when the main power supply voltage fluctuates due to engine cranking, the main power supply voltage may fall below a specified value, causing capacitor charging to be forcibly terminated. However, when capacitor charging is forcibly terminated, sufficient information for determining deterioration cannot be obtained, and deterioration determination is not performed using the capacity calculated in this situation. Therefore, it is possible to accurately determine capacitor deterioration even in a vehicle in which capacitor charging is forcibly terminated due to cranking.

[0017] [Details of the Embodiments 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 defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In each drawing, for the convenience of explanation, some components may be exaggerated or simplified. Furthermore, the dimensional proportions 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 also be, for example, an electric vehicle, a fuel cell vehicle, or a hydrogen vehicle.

[0019] 1 , the vehicle 2 has a main power supply 7 that is used as the power supply for the vehicle system 1 under normal circumstances, and a backup power supply 8 that is used as the power supply for the vehicle system 1 in an emergency. The main power supply 7 is, for example, a vehicle battery. In an emergency, for example, when an abnormality occurs in the main power supply 7 and the main power supply 7 is no longer able to supply power to the on-board devices 5, the backup power supply 8 supplies power to specific on-board devices 5 (e.g., backup target devices 9), which may be a part of the on-board devices 5. Examples of abnormalities that may occur in the main power supply 7 include a failure of the main power supply 7 and a break in the wiring provided to the main power supply 7.

[0020] 1, the on-vehicle equipment 5 includes on-vehicle electrical equipment 10 provided for each of various functions of the vehicle 2. Examples of the on-vehicle electrical equipment 10 include an engine device, a transmission device, a power window device, a door mirror device, an air conditioning 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 power from the main power supply 7, and operate on power from 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, running system electrical components 11 related to the running of the vehicle 2, and locking / unlocking system electrical components 12 related to the locking / unlocking of the doors of the vehicle 2. The running system electrical components 11 are, for example, a brake device. The locking / unlocking system electrical components 12 are, for example, a keyless entry device, a door lock device, etc.

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

[0023] 1 , the backup power supply 8 has an on-board capacitor device 18 that charges and discharges a capacitor 19, which is a power storage element. The on-board capacitor device 18 has a power supply control unit 20 that controls the operation of the on-board capacitor device 18, and a charge / discharge circuit unit 21 that charges and discharges the capacitor 19. The on-board 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 also 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 obtained 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 to the backup target device 9 from the third port 16.

[0026] When the system control unit 3 receives a vehicle power-on signal (e.g., an ignition-on signal), it outputs a charging start request to the power supply control unit 20. When the power supply control unit 20 receives a charging start request from the system control unit 3, the charging / discharging control unit 22 causes the charging / discharging circuit unit 21 to charge the capacitor 19. In this manner, the charging / discharging circuit unit 21 starts charging when the vehicle 2 is turned on. In this example, when the vehicle 2 is turned on, the charging / discharging circuit unit 21 inputs power from the main power supply 7 through the second port 15 and sends this power to the capacitor 19, thereby charging the capacitor 19. It is preferable that the charging / discharging control unit 22 continue charging until the voltage of the capacitor 19 (hereinafter referred to as the capacitor voltage Vc) reaches or exceeds a predetermined value, or until the charging time reaches or exceeds 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 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 the 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 be discharged to a constant voltage 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 the power supply control unit 20. When the power supply control unit 20 receives the discharge start request from the system control unit 3, the charge / discharge control unit 22 causes the charge / discharge circuit unit 21 to discharge capacitor 19. Specifically, the charge / discharge circuit unit 21 discharges the power of capacitor 19 via the charge / discharge circuit unit 21, thereby reducing the voltage of capacitor 19 to a constant value. This makes it possible to maintain the voltage of capacitor 19 at a constant value.

[0029] 1, the in-vehicle capacitor device 18 has a function (capacitor degradation determination function) for determining degradation of the capacitor 19. The capacitor degradation determination function in 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 being charged. If 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 the current Ic flowing through the capacitor 19, and a voltage detection unit 25 that detects the 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, which is, 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 calculates or acquires current Ic flowing through capacitor 19 during charging and voltage change ΔV across capacitor 19 that occurs 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 degradation determination unit 28 that determines degradation of the capacitor 19 based on the capacitance C calculated by the capacitance calculation unit 26. The degradation determination unit 28 is provided in the power supply control unit 20. The degradation determination unit 28 compares the capacitance C calculated by the capacitance calculation unit 26 with a predetermined value, and determines that no degradation has occurred in the capacitor 19 if the capacitance C is equal to or greater than the predetermined value. On the other hand, the degradation 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 a previous calculation result.

[0036] Next, the operation of the on-board capacitor device 18 of this embodiment will be described. (Calculation of Capacitance of Capacitor 19) As shown in Fig. 2, charging of the capacitor 19 begins when the ignition of the vehicle power supply is turned on. In this example, the charge / discharge control unit 22 begins 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 begins, a current Ic flows from the main power supply 7 to the capacitor 19, and the capacitor voltage Vc increases. Note that, in order to avoid early deterioration, it is preferable to leave a certain amount of capacitance C in the capacitor 19 rather than completely emptying it before charging begins.

[0037] After the transient period 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 period Ta in which the capacitor voltage Vc is unstable. This is to acquire a stable value of the first voltage V1.

[0038] The capacitance calculation unit 26 samples the current Ic at sampling intervals ts during a predetermined sampling period. The sampling period refers to the period from the start to the end of sampling of the current Ic. The sampling time Tc of the current Ic is preferably, for example, a value obtained by multiplying the sampling interval 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 (herein 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 capacity calculation unit 26 calculates the capacity C according to Equation 1 using the current Ic (average value Ik in this example), the sampling time Tc, the first voltage V1, and the second voltage V2: C=(Ic×Tc) / (V2−V1) Equation 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 retained in the memory 27 even when the ignition of the vehicle power supply is turned off.

[0041] The deterioration determination unit 28 determines whether the capacitor 19 has deteriorated based on the capacitance C calculated by the capacitance calculation unit 26. If the capacitance C is less than a predetermined value, the deterioration determination unit 28 determines that the capacitor 19 has deteriorated. If the deterioration determination unit 28 determines that the capacitor 19 has deteriorated, the deterioration determination unit 28 may, for example, display a message on the instrument panel at the driver's seat or issue a warning using a speaker inside the vehicle, thereby notifying the user that the capacitor 19 is in a deteriorated state.

[0042] In this example, since the first voltage V1 is acquired while avoiding the transient region Ta, it is possible to acquire the voltage change ΔV with high accuracy. Also, since the current Ic is sampled a sufficient number of times, it is possible to calculate or acquire "Ic x Tc" in Equation 1 with high accuracy. Furthermore, since the second voltage V2 is acquired after a sufficient charging time, it further contributes to ensuring a high accuracy of the voltage change ΔV.

[0043] (Phenomenon at Engine Start) 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, and therefore 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 takes on a waveform that drops significantly due to cranking.

[0044] Incidentally, if 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 will 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 value sufficient to charge the capacitor 19. Therefore, the charging of the capacitor 19 that started when the ignition was turned on is not terminated midway but continues. In other words, the charging of the capacitor 19 that has started once is not forcibly terminated midway due to cranking.

[0045] (Issues in Capacitance Calculation) Fig. 4 shows the waveform of the main power supply voltage Vb (main power supply voltage waveform S1), the waveform of the capacitor voltage Vc (capacitor voltage waveform S2), and the 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 Figure 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 begins, the main power supply voltage Vb falls below the specified value Vb1, and charging immediately terminates. In this case, as shown by the capacitor voltage waveform S2 in Figure 4, the charging time is very short, and the voltage change ΔV is small. Therefore, the capacitance C cannot be calculated accurately.

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

[0048] When the amount of voltage change ΔV is not 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 the amount of voltage change ΔV is not 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. Therefore, it is possible to perform deterioration determination using a value of capacitance C that is 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, if 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 if 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 falls below the capacitance calculation end threshold Ic1. When the current Ic falls below the capacitance calculation end 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 Figure 5, when the main power supply voltage Vb drops due to cranking or the like, the capacity calculation is stopped if the current Ic drops below the capacity calculation end threshold Ic1, even if the main power supply voltage Vb does not fall below the specified value Vb1. Therefore, the capacity calculation is stopped even in an unstable state where the current Ic falls below the capacity calculation end threshold Ic1 even though there is no significant drop in the main power supply voltage Vb. This further contributes to ensuring the accuracy of the capacity calculation.

[0052] (Averaging Capacitance C) As shown in FIG. 6 , the degradation determination unit 28 may calculate or acquire the average value Cave of the multiple capacitances C calculated by the capacity calculation unit 26 each time charging is performed, and use the average value Cave to determine degradation. Specifically, the degradation determination unit 28 calculates the average value Cave of the capacitances C (C1, C2, ... Cn) calculated in each drive cycle. In this case, even if an abnormal value is suddenly calculated for capacitance C, averaging the capacitances C makes it possible to minimize the impact of this abnormal value. This further contributes to ensuring the accuracy of degradation determination for capacitor 19.

[0053] (Effects of the Embodiment) The configuration of the above embodiment provides the following effects. (1) The on-board capacitor device 18 has a capacitor 19 that is charged by the on-board main power supply 7 when the main power supply voltage Vb supplied from the main power supply 7 is equal to or greater than a specified value Vb1. The on-board capacitor device 18 outputs the power of the capacitor 19 as a backup power source for the main power supply 7 in an emergency. The capacitance calculation unit 26 included in the on-board capacitor device 18 calculates or acquires the current Ic flowing through the capacitor 19 during charging and the voltage change ΔV of the capacitor 19 that occurs 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 ΔV. The deterioration determination unit 28 included in the on-board capacitor device 18 determines deterioration of the capacitor 19 based on the capacitance C calculated by the capacitance calculation unit 26. The deterioration determination unit 28 performs deterioration determination using a calculation result of the capacitance calculation unit 26 that satisfies that the voltage change ΔV is equal to or greater than a threshold.

[0054] According to this configuration, charging of capacitor 19 is performed only when the main power supply voltage Vb is equal to or greater than a specified value Vb1. Therefore, if the main power supply voltage Vb falls below Vb1, charging is forcibly stopped. In this case, charging is terminated prematurely, and a sufficient number of samples of the current Ic of capacitor 19 cannot be obtained. This prevents accurate calculation or acquisition of the capacitance C of capacitor 19, resulting in poor degradation assessment accuracy. However, if charging of capacitor 19 is forcibly terminated, the voltage change ΔV should be small because sufficient charging time was not provided. Focusing on this point, degradation assessment is performed using the calculation results of capacitance calculation unit 26 that satisfy the condition that the voltage change ΔV is equal to or greater than a threshold. This improves the accuracy of determining whether capacitor 19 is degraded.

[0055] (2) The degradation determination unit 28 performs degradation 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. With 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 acquired. This further contributes to the accurate calculation of the capacitance C of the capacitor 19. Therefore, it further contributes 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 performs deterioration determination using a 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 or acquires 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 the single value of capacitance C of capacitor 19 suddenly fluctuates, the influence of the sudden fluctuation in single value can be minimized by taking the average of capacitance C. This further contributes to improving the accuracy of determining whether or not capacitor 19 has deteriorated.

[0058] (5) The capacitance calculation unit 26 acquires the current Ic and the voltage change ΔV while avoiding the transient region Ta at the start of charging. This configuration allows the voltage change ΔV to be calculated or acquired during a period in which the voltage change is stable, contributing to the acquisition of an appropriate voltage change 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 calculates or acquires the total current "Ic x Tc" flowing through the capacitor 19 during the sampling period, and divides the total current "Ic x Tc" by the 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 calculation formula.

[0060] (7) The capacitor 19 supplies power to the backup target devices 9. The backup target devices 9 include at least one of the traveling system electrical components 11 related to the traveling of the vehicle 2 and the locking / unlocking system electrical components 12 related to the locking / unlocking of the doors of the vehicle 2. This configuration allows the capacitor 19 to stably supply backup power to the electrical components related to stopping the traveling of the vehicle 2 or getting out of the vehicle. This contributes to ensuring safety when driving the vehicle.

[0061] (8) A vehicle 2 equipped with a capacitor 19 has an engine 4 as a driving source. The main power supply voltage Vb fluctuates due to cranking when the engine 4 is started. With this configuration, when the main power supply voltage Vb fluctuates due to cranking of the engine 4, the main power supply voltage Vb may fall below a specified value Vb1, causing charging of the capacitor 19 to be forcibly terminated. However, when charging of the capacitor 19 is forcibly terminated, sufficient information for determining deterioration cannot be obtained, and therefore deterioration determination is not performed using the capacitance C calculated in this situation. Therefore, deterioration of the capacitor 19 can be accurately determined even in a vehicle 2 in which charging of the capacitor 19 is forcibly terminated due to cranking.

[0062] [Other Embodiments] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0063] The conditions for calculating the capacitance 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 samplings 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 capacitance C are not satisfied is not limited to the method in which the capacitance calculation unit 26 discards the calculation result. For example, a method in which the degradation determination unit 28 does not acquire the calculation result, or a method in which the capacity calculation unit 26 terminates the calculation midway may be adopted.

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

[0066] The power supply control unit 20 in the illustrated non-limiting embodiment may be referred to as a controller, which may be configured as a computer. This controller may include, for example, at least one memory configured to store a program including computer-executable instructions and at least one processor configured to execute processing based on the program. The memory 27 in the illustrated non-limiting embodiment may be included in the at least one memory or may be the at least one memory itself. Data, including the specified value Vb1, used when executing processing based on the program may be stored in the at least one memory in advance and / or temporarily stored during the processing. The specified value Vb1 in the illustrated non-limiting embodiment may be referred to as a specified voltage value. The charge / discharge control unit 22, capacity calculation unit 26, and degradation determination unit 28 in the illustrated non-limiting embodiment may be included in the at least one processor or may be the at least one processor itself. The power supply control unit 20 may include an interface (I / F) configured to receive signals directly or indirectly from one or more electrical circuit elements and / or transmit signals directly or indirectly to the one or more electrical circuit elements. The one or more electric circuit elements may include a capacitor 19, a current detection unit 24, a voltage detection unit 25, a system control unit 3, and a main power supply 7. The interface of the power supply control unit 20 may be a wired and / or wireless communication interface.

[0067] [Supplementary Note 1] One example of the present disclosure is directed to a controller for use with a vehicle (2) having a main power supply (7) for supplying a main power supply voltage (Vb) to one or more on-board devices (5), and a capacitor (19) included in a backup power supply (8) that is charged by the main power supply (7). The controller may include: a memory (27) configured to store a program including computer-executable instructions and data including a specified voltage value (Vb1); processors (22, 26, 28) configured to execute processing based on the program; and an interface configured to be connected to at least the capacitor (19). the controller monitors the main power supply voltage (Vb); when the main power supply voltage (Vb) is equal to or greater than the specified voltage value (Vb1), supplies the main power supply voltage (Vb) to the one or more on-board devices (5), charges the capacitor (19) by supplying the main power supply voltage (Vb) to the capacitor (19), samples a capacitor current value (Ic) and a capacitor voltage value (Vc) over a sampling period that is included in the charging period of the capacitor (19) but excludes a rising transition period of the capacitor voltage (Vc), and stores a sampling start voltage value (V1) that is the capacitor voltage value (Vc) at the start of the sampling period; and in an emergency of the main power supply (7), including when the main power supply voltage (Vb) is less than the specified value (Vb1), supplies the voltage of the capacitor (19) to the one or more on-board devices (5) to back up the main power supply (7); The method may be configured to: calculate or acquire a capacitor voltage change (ΔV) occurring during the sampling period; calculate the capacitance of the capacitor (19) based on the capacitor voltage change (ΔV) and a plurality of capacitor current values ​​(Ic) sampled over the sampling period; and determine deterioration of the capacitor (19) not based on the calculated value of the capacitance of the capacitor (19) when the capacitor voltage change (ΔV) is less than a threshold value, but based on the calculated value of the capacitance of the capacitor (19) when the capacitor voltage change (ΔV) is equal to or greater than the threshold value.

[0068] While the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0069] REFERENCE SIGNS LIST 1 Vehicle system 2 Vehicle 3 System control unit 4 Engine 5 On-board equipment 7 Main power supply 8 Backup power supply 9 Backup target equipment 10 On-board electrical equipment 11 Traveling system electrical equipment 12 Locking / unlocking system electrical equipment 14 First port 15 Second port 16 Third port 18 On-board capacitor device 19 Capacitor 20 Power supply control unit 21 Charging / discharging circuit unit 22 Charging / discharging control unit 24 Current detection unit 25 Voltage detection unit 26 Capacity calculation unit 27 Memory 28 Deterioration determination unit C Capacitance ΔV Voltage change amount Ic Current Ik Average value S1 Main power supply voltage waveform S2 Capacitor voltage waveform S3 Capacitor current waveform Ta Transient region Tc Sampling time ts Sampling interval V1 First voltage V2 Second voltage Vb Main power supply voltage Vc Capacitor voltage Vb1 Specified value Ic1 Capacity calculation end determination threshold Cave Average value

Claims

1. An on-vehicle capacitor device having 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 that 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-vehicle capacitor device comprising: a capacity calculation unit that calculates or obtains 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, wherein 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.

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

3. The on-board capacitor device of claim 1, wherein the capacitance calculation unit discards the calculation result if the calculation does not satisfy a condition, and the deterioration determination unit performs deterioration determination using a past calculation result if the capacitance calculation unit discards the calculation result.

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

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

7. The on-board capacitor device according to claim 1, wherein the capacitor supplies power to equipment to be backed up, and the equipment to be backed up 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.

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

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