Charging device, charging control method, and control program

Abstract

To provide a charging device capable of effectively charging a secondary battery, a charge control method, and a control program.SOLUTION: A charging device comprises: a calculation section for calculating a deterioration integrated value representing a deterioration state of a secondary battery; a first determination section for determining whether or not the deterioration integrated value is equal to or more than a first threshold; a second determination section for determining, in a case where the deterioration integrated value is equal to or more than the first threshold, whether or not a value of current flowing through the secondary battery being charged is equal to or more than a second threshold; a third determination section for determining, in a case where the deterioration integrated value is less than the first threshold, whether or not a value of voltage applied to the secondary battery being charged is equal to or more than a third threshold; and a charge restriction section for performing the restriction of charging to the secondary battery, if it is determined that the value of the current flowing through the secondary battery being charged is equal to or more than the second threshold in the case where the deterioration integrated value is equal to or more than the first threshold or if it is determined that the value of the voltage applied to the secondary battery being charged is equal to or more than the third threshold in the case where the deterioration integrated value is less than the first threshold.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a charging device, a charging control method, and a control program.

Background Art

[0002] Patent Document 1 discloses a power supply system including a secondary battery and a control unit. When the temperature of the secondary battery is less than a predetermined temperature, the control unit controls the voltage of the secondary battery to fall between an upper limit voltage and a lower limit voltage. When the temperature of the secondary battery is greater than or equal to the predetermined temperature, the control unit controls the charge / discharge current of the secondary battery to be less than or equal to an upper limit current.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The power supply system disclosed in Patent Document 1 merely controls the voltage of the secondary battery or the charge / discharge current of the secondary battery according to the temperature of the secondary battery, and does not perform charge limitation considering the deterioration state of the secondary battery (i.e., the internal resistance of the secondary battery). Therefore, even when the resistance value of the secondary battery increases significantly due to high-rate deterioration or the like caused by high-current charge / discharge, the power supply system disclosed in Patent Document 1 may perform charge limitation on the secondary battery being charged based on the voltage state applied to the secondary battery being charged. In that case, since the current flowing through the secondary battery being charged is excessively limited, the actual charge amount becomes less than the chargeable amount at which Li (lithium) does not precipitate on the negative electrode of the secondary battery. Therefore, the power supply system disclosed in Patent Document 1 has a problem that the secondary battery cannot be effectively charged.

[0005] This disclosure is made in view of the above background and aims to provide a charging device, a charging control method, and a control program that can effectively charge a secondary battery. [Means for solving the problem]

[0006] The charging device according to this disclosure is a charging device for charging a secondary battery and comprises: a calculation unit that calculates a cumulative degradation value representing the degradation state of the secondary battery; a first determination unit that determines whether the cumulative degradation value is equal to or greater than a first threshold; a second determination unit that determines whether the value of the current flowing through the secondary battery during charging is equal to or greater than a second threshold if the cumulative degradation value is equal to or greater than the first threshold; a third determination unit that determines whether the value of the voltage applied to the secondary battery during charging is equal to or greater than a third threshold if the cumulative degradation value is less than the first threshold; and a charging limiting unit that limits charging to the secondary battery when the cumulative degradation value is equal to or greater than the first threshold and the value of the current flowing through the secondary battery during charging is determined to be equal to or greater than the second threshold, or when the cumulative degradation value is less than the first threshold and the value of the voltage applied to the secondary battery during charging is determined to be equal to or greater than the third threshold. This charging device can prevent excessive charging of a secondary battery by limiting charging to the secondary battery based on the value of the current flowing through the secondary battery during charging, for example, when the resistance value of the secondary battery increases due to high-rate degradation caused by high-current charging and discharging. In other words, this charging device can effectively charge rechargeable batteries.

[0007] The charging control method according to this disclosure is a charging control method by a charging device that charges a secondary battery, and includes calculating an integrated degradation value representing the degradation state of the secondary battery, determining whether the integrated degradation value is equal to or greater than a first threshold, determining whether the value of the current flowing through the secondary battery during charging is equal to or greater than a second threshold if the integrated degradation value is equal to or greater than the first threshold, determining whether the value of the voltage applied to the secondary battery during charging is equal to or greater than a third threshold if the integrated degradation value is less than the first threshold, and restricting charging to the secondary battery if the value of the current flowing through the secondary battery during charging is determined to be equal to or greater than the second threshold when the integrated degradation value is equal to or greater than the first threshold, or if the value of the voltage applied to the secondary battery during charging is determined to be equal to or greater than the third threshold when the integrated degradation value is less than the first threshold. This charging control method can prevent excessive charging of a secondary battery by restricting charging to the secondary battery based on the value of the current flowing through the secondary battery during charging, for example, when the resistance value of the secondary battery increases due to high-rate degradation caused by high-current charging and discharging. In other words, this charging control method allows for effective charging of secondary batteries.

[0008] The control program according to this disclosure is a control program that causes a computer to execute a charge control process in a charging device that charges a secondary battery, and causes the computer to execute the following: a process of calculating an accumulated degradation value representing the degradation state of the secondary battery; a process of determining whether the accumulated degradation value is equal to or greater than a first threshold; if the accumulated degradation value is equal to or greater than the first threshold, a process of determining whether the value of the current flowing through the secondary battery during charging is equal to or greater than a second threshold; if the accumulated degradation value is less than the first threshold, a process of determining whether the value of the voltage applied to the secondary battery during charging is equal to or greater than a third threshold; and if the accumulated degradation value is equal to or greater than the first threshold and the value of the current flowing through the secondary battery during charging is determined to be equal to or greater than the second threshold, or if the accumulated degradation value is less than the first threshold and the value of the voltage applied to the secondary battery during charging is determined to be equal to or greater than the third threshold, a process of restricting charging to the secondary battery. This control program prevents excessive charging of the secondary battery by limiting the charging of the secondary battery based on the value of the current flowing through the secondary battery during charging, for example, when the resistance of the secondary battery increases due to high-rate degradation caused by high-current charging and discharging. In other words, this control program can effectively charge the secondary battery. [Effects of the Invention]

[0009] This disclosure provides a charging device, a charging control method, and a control program that can effectively charge a secondary battery. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing an example configuration of a charging system equipped with the charging device described herein. [Figure 2] This is a flowchart showing the operation of the charging device related to this disclosure. [Modes for carrying out the invention]

[0011] The present invention will be described below through embodiments, but the claims are not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential for solving the problem. For clarity of explanation, the following descriptions and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations have been omitted where necessary.

[0012] Figure 1 is a block diagram showing an example configuration of a charging system 1 equipped with the charging device according to this disclosure. The charging device according to this disclosure can prevent excessive charging of a secondary battery when the resistance value of the secondary battery increases due to high-rate degradation caused by high-current charging and discharging, for example. In other words, the charging device according to this disclosure can effectively charge a secondary battery. A detailed explanation follows below.

[0013] As shown in Figure 1, the charging system 1 comprises a charging device 10 and a secondary battery 20 to be charged. The secondary battery 20 is a rechargeable battery such as a lithium-ion battery.

[0014] The charging device 10 is a device for charging the secondary battery 20. Specifically, the charging device 10 includes a calculation unit 11, a first determination unit 12, a second determination unit 13, a third determination unit 14, and a charging limiting unit 15.

[0015] The calculation unit 11 calculates a cumulative degradation value (ΣD) that represents the degradation state of the secondary battery 20. Here, the degradation state of the secondary battery 20 refers to the degree of increase in the internal resistance value of the secondary battery 20. Generally, the more the secondary battery 20 degrades over time, the higher its resistance value becomes. In particular, high-rate degradation caused by high-current charging and discharging further increases the resistance value of the secondary battery 20. Note that a larger cumulative degradation value indicates a higher resistance value of the secondary battery 20, and a smaller cumulative degradation value indicates a lower resistance value of the secondary battery 20.

[0016] The first determination unit 12 determines whether or not the degradation integrated value is greater than or equal to a first threshold value (threshold value of the degradation integrated value). In other words, the first determination unit 12 determines whether or not the resistance value of the secondary battery 20 is greater than or equal to a predetermined value.

[0017] The second determination unit 13 monitors the current flowing through the secondary battery 20 during charging. Specifically, when it is determined by the first determination unit 12 that the degradation integrated value is greater than or equal to the first threshold value, the second determination unit 13 determines (monitors) whether or not the value of the current flowing through the secondary battery 20 during charging is greater than or equal to a second threshold value (lower limit value of the unacceptable current).

[0018] The third determination unit 14 monitors the voltage applied to the secondary battery 20 during charging. Specifically, when it is determined by the first determination unit 12 that the degradation integrated value is less than the first threshold value, the third determination unit 14 determines (monitors) whether or not the value of the voltage applied to the secondary battery 20 during charging current is greater than or equal to a third threshold value (lower limit value of the unacceptable voltage).

[0019] The charge limiting unit 15 restricts the charging of the secondary battery 20 based on the determination results of the second determination unit 13 and the third determination unit 14.

[0020] For example, when it is determined that the value of the current flowing through the secondary battery 20 during charging is greater than or equal to the second threshold value when the degradation integrated value is greater than or equal to the first threshold value, the charge limiting unit 15 restricts the charging of the secondary battery 20 so that the value of the current flowing through the secondary battery 20 during charging becomes less than the second threshold value.

[0021] Also, when it is determined that the value of the voltage applied to the secondary battery 20 during charging is greater than or equal to the third threshold value when the degradation integrated value is less than the first threshold value, the charge limiting unit 15 restricts the charging of the secondary battery 20 so that the value of the voltage applied to the secondary battery 20 during charging becomes less than the third threshold value.

[0022] Here, when the resistance value of the secondary battery 20 increases significantly due to high-rate degradation or the like caused by charging and discharging with a large current, in the charge limit based on the voltage applied to the secondary battery 20 during charging, the current flowing through the secondary battery 20 during charging is excessively limited, so that the actual charge amount becomes less than the chargeable amount in which Li does not precipitate on the negative electrode of the secondary battery 20.

[0023] Therefore, when the resistance value of the secondary battery 20 increases significantly due to high-rate degradation or the like caused by charging and discharging with a large current (specifically, when the degradation integrated value is equal to or greater than the first threshold value), the charge limiting unit 15 does not limit the charge of the secondary battery 20 based on the voltage applied to the secondary battery 20 during charging, but based on the current flowing through the secondary battery 20 during charging. Thereby, the charging device 10 can prevent the current flowing through the secondary battery 20 during charging from being excessively limited, so that the secondary battery 20 can be effectively charged.

[0024] Subsequently, the operation of the charging device 10 will be described with reference to FIG. 2. FIG. 2 is a flowchart showing the operation of the charging device 10.

[0025] First, the charging device 10 calculates a degradation integrated value (ΣD) representing the degradation state of the secondary battery 20 to be charged (step S101). Specifically, the charging device 10 calculates the resistance value of the secondary battery 20 to be charged.

[0026] Thereafter, the charging device 10 determines whether the degradation integrated value is equal to or greater than the first threshold value (step S102).

[0027] For example, when the degradation integrated value is less than the first threshold value (NO in step S102), that is, when the resistance value of the secondary battery 20 is relatively small, the charging device 10 monitors the voltage applied to the secondary battery 20 during charging (step S103).

[0028] Specifically, the charging device 10 determines (monitors) whether the voltage applied to the secondary battery 20 during charging is equal to or greater than the third threshold (step S104). For example, if the voltage applied to the secondary battery 20 during charging is less than the third threshold (YES in step S104), that is, if the voltage applied to the secondary battery 20 during charging is within the acceptable range, the charging device 10 does not restrict charging of the secondary battery 20. On the other hand, if the voltage applied to the secondary battery 20 during charging is equal to or greater than the third threshold (YES in step S104), that is, if the voltage applied to the secondary battery 20 during charging is outside the acceptable range, the charging device 10 restricts charging of the secondary battery 20 so that the voltage applied to the secondary battery 20 during charging falls within the acceptable range (step S105).

[0029] Furthermore, if the cumulative degradation value is greater than or equal to the first threshold (YES in step S102), that is, if the resistance value of the secondary battery 20 is relatively high due to high-rate degradation or the like, the charging device 10 monitors the current flowing through the secondary battery 20 during charging (step S106).

[0030] Specifically, the charging device 10 determines (monitors) whether the value of the current flowing through the secondary battery 20 during charging is equal to or greater than the second threshold (step S107). For example, if the value of the current flowing through the secondary battery 20 during charging is less than the second threshold (NO in step S107), that is, if the value of the current flowing through the secondary battery during charging is within the acceptable range, the charging device 10 does not restrict charging to the secondary battery 20. On the other hand, if the value of the current flowing through the secondary battery 20 during charging is equal to or greater than the second threshold (YES in step S107), that is, if the value of the current flowing through the secondary battery 20 during charging is outside the acceptable range, the charging device 10 restricts charging to the secondary battery 20 so that the value of the current flowing through the secondary battery 20 during charging falls within the acceptable range (step S108).

[0031] Subsequently, if the secondary battery 20 is not fully charged (NO in step S109), the charging device 10 repeats the processes in steps S101 to S109. If the secondary battery 20 is fully charged (YES in step S109), the charging process is terminated.

[0032] Thus, the charging device 10 according to this disclosure limits the charging of the secondary battery 20 based on the current flowing through the secondary battery 20 during charging, for example, when the internal resistance of the secondary battery 20 increases significantly due to high-rate degradation caused by high-current charging and discharging. As a result, the charging device 10 according to this disclosure can prevent excessively limiting the current flowing through the secondary battery 20 during charging, and can effectively charge the secondary battery.

[0033] Furthermore, this disclosure can be realized by having a CPU (Central Processing Unit) execute a computer program to perform some or all of the processing of the charging device 10.

[0034] The program described above includes, when loaded into a computer, a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include RAM (Random-Access Memory), ROM (Read-Only Memory), flash memory, SSD (Solid-State Drive), or other memory technologies, CD-ROM, DVD (Digital Versatile Disc), Blu-ray® disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically, or otherwise propagating signals. [Explanation of symbols]

[0035] 1 Charging System 10 Charging device 11 Calculation Section 12 1st Judgment Section 13 Second Judgment Section 14 Third Judgment Section 15. Charging limiting section 20 Secondary battery

Claims

1. A charging device for charging secondary batteries, A first determination unit that determines whether the resistance value of the secondary battery is equal to or greater than a first threshold, If the resistance value of the secondary battery is equal to or greater than a first threshold, a second determination unit determines whether the value of the current flowing through the secondary battery during charging is equal to or greater than a second threshold, If the resistance value of the secondary battery is less than a first threshold, a third determination unit determines whether the voltage applied to the secondary battery during charging is greater than or equal to a third threshold, A charging limiting unit is provided that, when the resistance value of the secondary battery is equal to or greater than a first threshold and the value of the current flowing through the secondary battery during charging is determined to be equal to or greater than a second threshold, or when the resistance value of the secondary battery is less than a first threshold and the value of the voltage applied to the secondary battery during charging is determined to be equal to or greater than a third threshold, the charging limiting unit restricts the charging of the secondary battery. A charging device equipped with this.

2. The charging limiting unit, when it is determined that the value of the current flowing through the secondary battery during charging is greater than or equal to a second threshold when the resistance value of the secondary battery is greater than or equal to a first threshold, limits the charging of the secondary battery so that the value of the current flowing through the secondary battery during charging is less than the second threshold; and when it is determined that the value of the voltage applied to the secondary battery during charging is greater than or equal to a third threshold when the resistance value of the secondary battery is less than the first threshold, it limits the charging of the secondary battery so that the value of the voltage applied to the secondary battery during charging is less than the third threshold. The charging device according to claim 1.

3. A charging control method for a charging device that charges a secondary battery, Determine whether the resistance value of the secondary battery is equal to or greater than a first threshold. If the resistance value of the secondary battery is equal to or greater than the first threshold, it is determined whether the value of the current flowing through the secondary battery during charging is equal to or greater than the second threshold. If the resistance value of the secondary battery is less than the first threshold, it is determined whether the voltage applied to the secondary battery during charging is equal to or greater than the third threshold. If the resistance of the secondary battery is equal to or greater than a first threshold and the current flowing through the secondary battery during charging is determined to be equal to or greater than a second threshold, or if the resistance of the secondary battery is less than a first threshold and the voltage applied to the secondary battery during charging is determined to be equal to or greater than a third threshold, then charging of the secondary battery is restricted. Charging control method.

4. A control program that causes a computer to execute a charge control process in a charging device that charges a secondary battery, A process for determining whether the resistance value of the secondary battery is equal to or greater than a first threshold, If the resistance value of the secondary battery is equal to or greater than a first threshold, the process of determining whether the value of the current flowing through the secondary battery during charging is equal to or greater than a second threshold is performed. If the resistance value of the secondary battery is less than a first threshold, a process is performed to determine whether the voltage applied to the secondary battery during charging is equal to or greater than a third threshold. If the resistance value of the secondary battery is equal to or greater than a first threshold and the value of the current flowing through the secondary battery during charging is determined to be equal to or greater than a second threshold, or if the resistance value of the secondary battery is less than a first threshold and the value of the voltage applied to the secondary battery during charging is determined to be equal to or greater than a third threshold, a process is performed to restrict charging of the secondary battery. A control program that instructs a computer to execute a command.

Images