Vehicle power supply system

Abstract

To provide a vehicle power supply system capable of increasing precision of data related to determination of a softening degradation state of a battery.SOLUTION: A vehicle power supply system including a battery supplying power to an on-vehicle load includes: an acquisition unit acquiring information regarding discharge of a battery; a derivation unit deriving a current life discharge amount of a battery on the basis of the information regarding discharge of the battery acquired by the acquisition unit and a correlation between a discharge depth and a life discharge amount that the battery has; and an arithmetic unit computing data regarding determination of a softening degradation state of the battery on the basis of the current life discharge amount of the battery derived by the derivation unit and the information regarding discharge of the battery acquired by the acquisition unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power supply system mounted on a vehicle.

Background Art

[0002] Patent Document 1 discloses a power supply system that can accurately determine the softening deterioration of a lead battery used to supply power to an electrical load of a vehicle. In this power supply system, the charge amount, discharge amount, and depth of discharge of the lead battery are respectively obtained, and the softening deterioration of the lead battery is determined based on the obtained charge amount, discharge amount, and depth of discharge of the lead battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The life discharge amount of the battery, which is a criterion for determining the softening deterioration of the battery, is estimated, for example, by a single-cell test of the battery. However, the discharge pattern used in this single-cell test of the battery is generally a pattern with a constant depth of discharge. For this reason, there is a problem that the life discharge amount estimated by the single-cell test of the battery deviates from the life discharge amount based on various patterns of the depth of discharge actually occurring in vehicles used in the market.

[0005] Therefore, there is room for further study on a method for accurately determining the softening deterioration of the battery.

[0006] The present disclosure has been made in view of the above problems, and an object thereof is to provide a vehicle power supply system capable of improving the accuracy of data related to the determination of the softening deterioration state of the battery.

Means for Solving the Problem

[0007] To solve the above problems, one aspect of the disclosed technology is a vehicle power supply system including a battery that supplies power to in-vehicle loads, the vehicle power supply system comprising: an acquisition unit that acquires information regarding the discharge of the battery; a derivation unit that derives the current remaining discharge capacity of the battery based on the information regarding the discharge of the battery acquired by the acquisition unit and the correlation between the depth of discharge and the remaining discharge capacity of the battery; and a calculation unit that calculates data related to the determination of the softening degradation state of the battery based on the current remaining discharge capacity of the battery derived by the derivation unit and the information regarding the discharge of the battery acquired by the acquisition unit.

Advantages of the Invention

[0008] According to the vehicle power supply system of the present disclosure, data related to the determination of the softening degradation state of the battery is calculated based on the information regarding the discharge of the battery and the correlation between the depth of discharge and the remaining discharge capacity of the battery. Thereby, the accuracy of the data related to the determination of the softening degradation state of the battery can be improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] The vehicle power supply system of the present disclosure derives the remaining discharge capacity of the current battery based on the history of the depth of discharge that has occurred in the current battery and the correlation between the depth of discharge and the remaining discharge capacity of the battery obtained in advance by simulation or the like. Then, from the derived remaining discharge capacity of the current battery and the cumulative discharge amount of the battery so far, the softening deterioration rate of the battery is calculated. Thereby, the accuracy of determining the softening deterioration state of the battery can be improved. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0011] <Embodiment> [Configuration] FIG. 1 is a schematic diagram for explaining a configuration example of a vehicle power supply system 100 according to an embodiment of the present disclosure. The vehicle power supply system 100 illustrated in FIG. 1 includes a battery 200 and a battery management device 300. This vehicle power supply system 100 is mounted on a vehicle, for example.

[0012] The battery 200 is a secondary battery configured to be chargeable and dischargeable, such as a lead-acid battery or a lithium-ion battery, for example. This battery 200 can supply power (discharge) required for auxiliary in-vehicle loads (not shown) other than driving the vehicle, or receive power supply from a main in-vehicle load (not shown) for driving the vehicle (charge). As the battery 200, a so-called auxiliary battery can be exemplified.

[0013] The battery management device 300 is a device that can perform management of the battery 200, including processing for determining the softening deterioration state of the battery 200. This battery management device 300 includes an acquisition unit 310, a derivation unit 320, and a calculation unit 330.

[0014] The acquisition unit 310 is configured to acquire information regarding the discharge of the battery 200. The information regarding the discharge of the battery 200 includes at least the "cumulative discharge amount", which is the amount of electric power discharged (supplied) by the battery 200 to auxiliary devices and the like so far, the "actual depth of discharge", which is the depth of discharge actually occurring in the battery 200 during the discharge, and the "number of occurrences (or occurrence frequency)" of each actual depth of discharge.

[0015] FIG. 2 is a diagram showing an example image in which the information on the actual depth of discharge and the number of occurrences of the battery 200 acquired by the acquisition unit 310 is represented in a correspondence table. In the example of FIG. 2, the depth of discharge actually occurring in the battery 200 is divided into a plurality of levels according to its magnitude, and the number of times (or frequency) the depth of discharge has occurred is recorded for each of these levels.

[0016] Note that information on the current and temperature of the battery 200 may be included in the information regarding the discharge of the battery 200. The acquisition unit 310 can acquire the above-described information regarding the discharge of the battery 200 via various sensors (not shown) capable of detecting physical quantities of the battery 200.

[0017] The derivation unit 320 is configured to derive the current remaining discharge capacity of the battery 200 based on the information regarding the discharge of the battery 200 acquired by the acquisition unit 310 and the correlation between the depth of discharge and the remaining discharge capacity of the battery 200. Specifically, the derivation unit 320 identifies the actual depth of discharge of the battery 200 that satisfies a predetermined condition from the information regarding the discharge of the battery 200, and derives the remaining discharge capacity correlated with the identified actual depth of discharge as the current remaining discharge capacity of the battery 200.

[0018] As an example of such predetermined conditions, it can be exemplified that the depth of discharge is such that the number of occurrences (or occurrence frequency) is equal to or greater than a predetermined value, and among them, the maximum depth of discharge is used. For example, when the total number of occurrences shown in FIG. 2 is 100 times, the condition is that the number of occurrences is 2 or more (or the occurrence frequency is 2% or more) as the predetermined value, and the depth of discharge "6 - 7%", which is the maximum among the actual depths of discharge of 2 - 3%, 3 - 4%, 4 - 5%, 5 - 6%, and 6 - 7% that meet this condition, is specified by the derivation unit 320.

[0019] Next, the derivation unit 320 applies this specified actual depth of discharge to the correlation between the depth of discharge (stress) and the life discharge amount (strength) of the battery 200. FIG. 3 is a semi-logarithmic graph showing an example of the correlation between the depth of discharge and the life discharge amount of the battery 200. Such a correlation is created in advance by a single-product test of the battery 200, and is defined by a relational expression (Y = a × X^b) in which the value obtained by multiplying the coefficient a by the value obtained by raising the coefficient b to the power of the depth of discharge X is taken as the life discharge amount Y. Note that the coefficient a and the coefficient b are appropriately determined based on the capacity and characteristics of the battery 200 and the performance required for the vehicle.

[0020] For example, when the actual depth of discharge "6 - 7%", which can be specified from FIG. 2 described above, is applied to the correlation shown in FIG. 3, a value of approximately 300 - 500 Ah (white circle marks in FIG. 3) can be derived as the life discharge amount of the battery 200 in the state of use from when it was new (at the time of replacement) until now.

[0021] The calculation unit 330 is configured to calculate data related to the determination of the softening degradation state of the battery 200 based on the current life discharge amount of the battery 200 derived by the derivation unit 320 and the information on discharge acquired by the acquisition unit 310. As data related to the determination of the softening degradation state of the battery 200, for example, a "softening degradation rate" indicating the rate at which the degradation due to the softening of the active material of the battery 200 is progressing can be exemplified. Specifically, the calculation unit 330 calculates the softening degradation rate of the battery 200 based on the ratio of the cumulative discharge amount of the battery 200 to the current life discharge amount of the battery 200 using the cumulative discharge amount of the battery 200 among the information on the discharge of the battery 200 (softening degradation rate = cumulative discharge amount / current life discharge amount).

[0022] For example, when the current life discharge amount of the battery 200 derived by the derivation unit 320 from the correlation is 500 Ah and the cumulative discharge amount of the battery 200 acquired by the acquisition unit 310 is 250 Ah, the softening degradation rate of the battery 200 is calculated as "0.5 (= 250 / 500)".

[0023] Note that a part of the vehicle power supply system 100 (battery management device 300) described above can typically be configured as an electronic control unit (ECU: Electronic Control Unit) including a processor such as a microcomputer, a memory, and an input / output interface. By the processor reading and executing the program stored in the memory, part or all of the functions of the acquisition unit 310, derivation unit 320, and calculation unit 330 described above can be realized.

[0024] [Control] Next, with further reference to FIG. 4, the control executed by the vehicle power supply system 100 according to the present embodiment will be described. FIG. 4 is a flowchart for explaining the processing procedure of calculating the softening degradation rate of the battery 200 executed by the vehicle power supply system 100 (battery management device 300). The softening degradation rate calculation process of the battery 200 illustrated in FIG. 4 is executed, for example, every time the ignition switch of the vehicle is turned on (IG-ON).

[0025] (Step S401) The acquisition unit 310 of the vehicle power supply system 100 acquires information regarding the discharge of the battery 200. The information regarding the discharge of the battery 200 acquired by the acquisition unit 310 includes at least the cumulative discharge amount of the battery 200, a plurality of actual discharge depths, and the number of occurrences (or occurrence frequency) of each actual discharge depth. When the information regarding the discharge of the battery 200 is acquired by the acquisition unit 310, the process proceeds to step S402.

[0026] (Step S402) Based on the information regarding the discharge of the battery 200 acquired by the acquisition unit 310, the derivation unit 320 of the vehicle power supply system 100 identifies the discharge depth that has the maximum number of occurrences (or occurrence frequency) among the plurality of actual discharge depths and that is greater than or equal to a predetermined value. When the derivation unit 320 identifies the maximum discharge depth for which the number of occurrences (or occurrence frequency) is greater than or equal to the predetermined value, the process proceeds to step S403.

[0027] (Step S403) Based on the maximum discharge depth for which the number of occurrences (or occurrence frequency) is greater than or equal to the predetermined value identified in step S402 above and the correlation between the discharge depth and the life discharge amount of the battery 200, the derivation unit 320 of the vehicle power supply system 100 derives the current life discharge amount of the battery 200, which is the life discharge amount of the battery 200 in the current usage state. When the derivation unit 320 derives the current life discharge amount of the battery 200, the process proceeds to step S404.

[0028] (Step S404) Based on the current life discharge amount of the battery 200 derived by the derivation unit 320 and the cumulative discharge amount of the battery 200 acquired by the acquisition unit 310 as information regarding the discharge of the battery 200, the calculation unit 330 of the vehicle power supply system 100 calculates the softening deterioration rate of the battery 200. When the calculation unit 330 calculates the softening deterioration rate of the battery 200, the process of calculating the softening deterioration rate of the battery 200 ends.

[0029] The softening deterioration rate of the battery 200 calculated by the above processing is used to determine the softening deterioration state of the battery 200.

[0030] <Function and Effect> As described above, according to the vehicle power supply system 100 according to an embodiment of the present disclosure, based on information regarding the discharge of the battery 200 (the actual depth of discharge of the battery 200 and the number of occurrences of the actual depth of discharge) and the correlation between the depth of discharge and the life discharge amount of the battery 200, the current life discharge amount of the battery 200 is derived, and based on this derived current life discharge amount of the battery 200 and information regarding discharge (the cumulative discharge amount of the battery 200), the softening deterioration rate of the battery 200 is calculated.

[0031] By this processing, the accuracy of the softening deterioration rate of the battery 200, which is one of the data related to the determination of the softening deterioration state of the battery 200, can be improved.

[0032] As described above, although one embodiment of the present disclosure has been described, the present disclosure can be regarded as a vehicle power supply system, a control method executed by a vehicle power supply system including a processor and a memory, a control program for executing this control method, a computer-readable non-transitory storage medium storing the control program, and a vehicle equipped with the vehicle power supply system, and the like.

Industrial Applicability

[0033] The vehicle power supply system of the present disclosure can be used when it is desired to improve the accuracy of data related to the determination of the softening deterioration state of a battery mounted on a vehicle.

Explanation of Reference Numerals

[0034] 100 Vehicle power supply system 200 Battery 300 Battery management device 310 Acquisition unit 320 Derivation unit 330 Calculation unit

Claims

1. A vehicle power supply system including a battery that supplies power to an in-vehicle load, an acquisition unit that acquires information regarding discharge of the battery, a derivation unit that derives the current life discharge amount of the battery based on the information regarding discharge of the battery acquired by the acquisition unit and the correlation between the depth of discharge and the life discharge amount of the battery, and a calculation unit that calculates data related to determination of a softening deterioration state of the battery based on the current life discharge amount of the battery derived by the derivation unit and the information regarding discharge of the battery acquired by the acquisition unit. The acquisition unit acquires, as information regarding discharge of the battery, the cumulative discharge amount of the battery, the actual depth of discharge performed by the battery, and the number of occurrences of the actual depth of discharge. The derivation unit derives the current life discharge amount of the battery based on the actual depth of discharge performed by the battery, the number of occurrences of the actual depth of discharge, and the correlation. The calculation unit calculates a softening deterioration rate of the battery based on the cumulative discharge amount of the battery and the current life discharge amount of the battery. A vehicle power supply system.

2. The derivation unit identifies the maximum depth of discharge among the actual depths of discharge performed by the plurality of batteries, where the number of occurrences of the actual depth of discharge is equal to or greater than a predetermined value, and applies the maximum depth of discharge to the correlation to derive the current life discharge amount of the battery. The vehicle power supply system according to Claim 1.

3. The calculation unit calculates the softening deterioration rate of the battery based on the ratio of the cumulative discharge amount of the battery to the current life discharge amount of the battery. The vehicle power supply system according to Claim 1.

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