Secondary battery charging system

Abstract

To provide a charging system capable of appropriately limiting charging control by calculating to make damage large in the high SOC region on the basis of negative electrode potential and deposition potential.SOLUTION: A secondary battery charging system is configured to acquire negative electrode potential and deposition potential during rapid charging, calculate cumulative damage value to a battery, and restrict the rapid charging when the cumulative damage value is equal to or more than a threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charging system for a secondary battery. [Background technology]

[0002] Patent Document 1 discloses a battery charging method in which the charging current is controlled depending on the SOC (State Of Charge) region of the negative electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-82426 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, there was a problem that charging at a low current for a long time in a high SOC range would cause significant damage to the battery, making it necessary to limit charging. Specifically, to suppress high-rate degradation during rapid charging, the current is controlled according to the SOC range, but damage calculations for limiting the number of charges per day in the vehicle system depend only on the charging time. In this case, in the high SOC range, which is frequently used for charging in the market, damage may be underestimated despite the actual damage being large, which could delay reaching the limit threshold and prevent the limit from being applied, resulting in inappropriate charging limits. [Means for solving the problem]

[0005] In one embodiment, the secondary battery charging system is an invention related to battery protection control during rapid charging. When calculating damage, which is the basis for control, the system does not use the conventional time-dependent damage calculation, but instead calculates damage based on the cell negative electrode potential and deposition potential at the current value under each SOC-temperature condition. [Effects of the Invention]

[0006] According to the charging system for a secondary battery of the present disclosure, damage can be calculated to be greater in a high SOC region based on the negative electrode potential and the deposition potential, and charging control can be appropriately limited. [Brief explanation of the drawings]

[0007] [Figure 1] 3 is a flowchart showing an example of the operation of the charging system for a secondary battery according to the present embodiment. [Figure 2] 4 is a graph showing the relationship between the amount of damage and the elapsed time in the charging system for a secondary battery according to the present embodiment. [Figure 3] 4 is a graph showing current and charging cumulative damage relative to charging time in the charging system for a secondary battery according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] This embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Fig. 1 is a flowchart showing an example of the operation of a charging system for a secondary battery according to the present embodiment.

[0009] First, in step S101, the charging system starts rapid charging, and then the process proceeds to step S102.

[0010] In step S102, the charging system calculates damage caused by fast charging. For example, the amount of damage is set assuming a secondary battery temperature of 25°C / SOC of 15% is charged to 78%. An example of damage calculation during charging is shown below. Tables 1 and 2 below are examples of fast charging maps / battery limit current maps. [Table 1] [Table 2] Tables 1 and 2 are shown in graph form in Figure 2. Figure 2 is a graph showing the relationship between the amount of damage and the elapsed time in the charging system for a secondary battery according to this embodiment.

[0011] Here, the section damage in Tables 1 and 2 can be calculated using the following method. - Damage over a certain period (previously 1 damage / sec) is applied, so 1525 damage over 1525sec. Section damage (new) is damage / sec=1 / (negative electrode potential-deposition potential*) *This must be set for each cell, but is temporarily set to 0. · Section Damage (New_Converted) is converted so that the total damage is the same as Section Damage (Previous) (=1525), since the total of Section Damage (New) is 38850. [Table 3] [Table 4] A graph based on Tables 3 and 4 is shown in Fig. 3. Fig. 3 is a graph showing current and charging cumulative damage relative to charging time in a charging system for a secondary battery according to this embodiment. Then, the process proceeds to step S103.

[0012] In step S103, the charging system calculates an integrated damage value by integrating the damage calculated in step S102 and the charging history over time. It then determines whether the integrated damage value is equal to or greater than a predetermined control threshold. If the integrated damage value is equal to or greater than the predetermined control threshold, the process proceeds to step S104. If the integrated damage value is less than the predetermined control threshold, the process proceeds to step S107.

[0013] In step S104, the rapid charging is restricted, and the process then proceeds to step S105.

[0014] In step S105, the charging system reduces damage to the secondary battery being charged. Specifically, after charging starts, the charging system adds damage during charging, and after charging ends, it subtracts damage while not charging. Then, the process proceeds to step S106.

[0015] In step S106, the charging system determines whether the damage accumulation value is equal to or greater than a predetermined control threshold. If the damage accumulation value is equal to or greater than the predetermined control threshold, the process returns to step S101. If the damage accumulation value is less than the predetermined control threshold, the charging process ends.

[0016] In step S107, the charging system charges the secondary battery without restricting rapid charging, and then the process returns to step S101.

[0017] As described above, according to the charging system for a secondary battery of this embodiment, damage is significantly increased in the intermediate to high SOC range where the difference between the negative electrode potential and deposition potential, which is a weak point for Li deposition in BEV (Battery Electric Vehicle) cells, becomes small, and appropriate number of times limiting protection is applied when the battery is used in that range, thereby improving safety protection for customers.

[0018] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention. For example, a control with higher protection against Li deposition may be performed based on the principle of Li deposition (when the potential of the negative electrode surface is lower than the deposition potential, deposition occurs).

[0019] Each element shown in the drawings as a flowchart performing various processes can be configured in hardware by a CPU, memory, and other circuits, and in software by a program loaded into memory, etc. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various forms by hardware alone, software alone, or a combination thereof, and is not limited to any one of them.

[0020] The above-described program can be stored in and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible recording media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory)). The program can also be supplied to a computer by various types of temporary computer-readable media. Examples of temporary computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable media can be supplied to a computer via a wired communication path such as an electric wire or optical fiber, or via a wireless communication path.

Claims

[Claim 1] A charging system for a secondary battery that acquires the negative electrode potential and the precipitated battery during rapid charging, calculates the cumulative damage to the battery, and limits rapid charging if the cumulative damage value exceeds a threshold value.

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