Charging control device, charging control method, and charging control program

Abstract

The purpose of the present invention is to easily suppress deterioration of battery performance during charging. A charging control device for controlling the charging of a secondary battery (1) by supplying power from a power source (3) is provided with: a control unit (18) for controlling the power supplied from the power source (3); and a resistance acquisition unit (17) that determines the internal resistance (5) of the secondary battery (1), in which the power source (3) supplies power to the secondary battery (1) so as to be able to change the charging current (6), and the control unit (18) performs suppression control of the power source (3) so that the product of the charging current (6) and the internal resistance (5) becomes a predetermined threshold value (8) or less.

Description

Technical Field

[0001] The present invention relates to a charging control device, a charging control method, and a charging control program for controlling charging of a secondary battery. Background Art

[0002] The performance of secondary batteries deteriorates due to various factors during charging. Therefore, charging control is performed by various methods. For example, for lithium-ion batteries, lithium (Li) is precipitated from the negative electrode during low-temperature charging, thereby reducing battery performance. In order to suppress this phenomenon, in the invention disclosed in Patent Document 1, the potential of the negative electrode is obtained, and the input allowable power is adjusted so that the potential does not drop to the lithium reference potential.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2010 / 5079 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, it is not easy to determine the potential of the negative electrode with high accuracy, and it is not easy to suppress the degradation of battery performance.

[0008] An object of the present invention is to easily suppress degradation of battery performance during charging.

[0009] Solutions for solving problems

[0010] In order to achieve the above-mentioned purpose, a characteristic structure of a charging control device involved in one embodiment of the present invention is that, a charging control device is used to control the charging of a secondary battery by supplying electric power from a power supply, and the charging control device comprises: a control unit, which controls the electric power supplied from the power supply; and a resistance acquisition unit, which calculates the internal resistance of the secondary battery, wherein the power supply can supply the electric power to the secondary battery with a changed charging current, and the control unit performs suppression control of the power supply so that the product of the charging current and the internal resistance becomes below a predetermined threshold value.

[0011] In addition, a characteristic structure of a charging control method involved in one embodiment of the present invention is that, a charging control method is used to control the charging of a secondary battery by supplying electric power from a power source, and the charging control method comprises the following steps: calculating the internal resistance of the secondary battery; and performing suppression control of the power source so that the product of the charging current of the electric power and the internal resistance becomes below a predetermined threshold value.

[0012] In addition, a characteristic structure of a charging control program involved in one embodiment of the present invention is that it is a charging control program for controlling the charging of a secondary battery by supplying electric power from a power source, and the charging control program enables a computer to execute the following functions: calculating the internal resistance of the secondary battery; and performing suppression control of the power source so that the product of the charging current of the electric power and the internal resistance becomes below a predetermined threshold value.

[0013] The product of charging current and internal resistance is a standard for the influence of battery performance degradation. Therefore, according to the above-mentioned structures, charging control (suppression control) can be performed using the product of charging current and internal resistance as a standard for battery performance degradation, and the degradation of battery performance during charging can be easily suppressed.

[0014] Furthermore, the threshold value may be set in consideration of an overvoltage that can be allowed when charging the secondary battery.

[0015] The inventors have conducted extensive research and found that the relationship between overvoltage and the product of charging current and internal resistance affects the degradation of battery performance. According to the above structure, the threshold value can be set based on the overvoltage in consideration of this relationship, and the degradation of battery performance during charging can be easily suppressed.

[0016] Alternatively, the product of the charging current and the internal resistance may be varied experimentally and charging and discharging may be repeated, wherein the charging efficiency or the rate of decrease in full charge capacity may be measured each time charging and discharging is performed, and the product of the charging current and the internal resistance when the rate of decrease in the charging efficiency or the rate of decrease in the full charge capacity is less than a specified value may be determined as the threshold value.

[0017] With such a configuration, the threshold value can be generated with high accuracy, and degradation of battery performance during charging can be easily and accurately suppressed.

[0018] In addition, it is also possible that there is a temperature control unit, which controls the temperature of the secondary battery during charging, and the control unit controls the temperature of the secondary battery to control the internal resistance in a manner such that the product of the charging current and the internal resistance becomes below the threshold value during the suppression control.

[0019] The internal resistance depends on the temperature of the secondary battery. Therefore, the internal resistance can be changed by changing the temperature of the secondary battery. According to the above structure, by changing the temperature of the secondary battery, the product of the charging current and the internal resistance can be easily controlled, and the degradation of the battery performance during charging can be easily suppressed.

[0020] In addition, it may also be provided with: a storage unit which stores the initial full charge capacity of the secondary battery; and a capacity maintenance rate acquisition unit which calculates the capacity maintenance rate of the secondary battery based on the initial full charge capacity, and the control unit performs the suppression control so as to be less than the product of the threshold value and the capacity maintenance rate.

[0021] The situation in which the full charge capacity is reduced can be estimated as a situation in which the deterioration of the secondary battery is progressing.

[0022] According to the above configuration, the threshold value can be corrected according to the capacity maintenance rate indicating a decrease in the full charge capacity, and degradation of battery performance during charging can be suppressed more easily and accurately.

[0023] Furthermore, the device may further include a voltage measuring unit that measures a charging voltage during charging, and the control unit may perform the suppression control when the charging voltage is a predetermined upper limit voltage.

[0024] Suppression control can also be performed during charging, but the influence of suppression control is small when the charging voltage is low. According to the above structure, suppression control is performed only when the charging voltage is above the specified upper limit voltage, when the influence of suppression control becomes large, so that the degradation of battery performance during charging can be effectively suppressed.

[0025] In addition, it is also possible to further include a voltage measuring unit, which measures the charging voltage during charging, sets a different threshold value for each of a plurality of charging voltage segments, and the control unit performs the suppression control using the threshold value corresponding to each of the charging voltage segments.

[0026] The higher the charging voltage, the greater the effect of battery degradation on the product of charging current and internal resistance. Therefore, it is useful to change the threshold value according to the charging voltage. According to the above structure, the charging voltage during charging can be divided into a plurality of charging voltage segments, and a different threshold value can be set for each charging voltage segment, so that the degradation of battery performance during charging can be suppressed with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a diagram for explaining a configuration example of a charging control device.

[0028] Figure 2 It is a diagram illustrating the flow of charging control.

[0029] Figure 3 This is a diagram illustrating a method of setting a threshold value.

[0030] Figure 4 This is a diagram for explaining the effect of suppressing degradation obtained by performing charging control.

[0031] Figure 5 This is a diagram for explaining charging control performed during all charging periods.

[0032] Figure 6 It is a diagram for explaining the charging control performed in the charging voltage range.

[0033] Figure 7 It is a diagram for explaining charging control performed in a plurality of charging voltage stages. DETAILED DESCRIPTION

[0034] like Figure 1 As shown, a secondary battery 1 such as a lithium-ion battery receives power from a power source 3 to be charged. The battery voltage (CCV: Closed Circuit Voltage) during charging is represented by the sum of the terminal voltage (OCV: Open Circuit Voltage) when the secondary battery 1 is not connected and the charging current 6×internal resistance 5. When the product (IR) of the charging current 6 and the internal resistance 5 is too large, the secondary battery 1 during charging becomes an overvoltage state. Therefore, the product (IR) of the charging current 6 and the internal resistance 5 becomes an indicator of a factor of performance reduction (deterioration) of the secondary battery 1.

[0035] Therefore, the inventors have conducted intensive research and found that by controlling the product of the charging current 6 and the internal resistance 5 (IR) based on the voltage corresponding to the overvoltage, the degradation of the secondary battery 1 can be suppressed. Furthermore, the inventors have experimentally found a voltage value for controlling the overvoltage corresponding to the product of the charging current 6 and the internal resistance 5 (IR).

[0036] Therefore, the charging control device of the present embodiment performs the following control (suppression control of the power source 3): the power related to charging is suppressed in the power source 3 during charging so that the product (IR) of the charging current 6 and the internal resistance 5 becomes less than a predetermined threshold value 8. The threshold value 8 in this case is set in consideration of the allowable overvoltage when charging the secondary battery 1.

[0037] In this way, by controlling charging (performing suppression control on power source 3) using threshold value 8 obtained in consideration of overvoltage as one of the causes of degradation, it is possible to appropriately perform charging and easily suppress degradation of secondary battery 1. In addition, by performing suppression control on charging so that the product (IR) of charging current 6 and internal resistance 5 becomes equal to or less than threshold value 8, charging is suppressed by controlling only at least one of charging current 6 and internal resistance 5, so that it is possible to easily suppress degradation of secondary battery 1 while easily performing suppression control on charging.

[0038] [Charging control device]

[0039] Next, use Figure 1 , Figure 2 A configuration example for suppression control and a configuration example of a charging control device will be described.

[0040] As described above, the secondary battery 1 is charged by receiving power from the power source 3. At this time, an ammeter 11 for measuring the charging current 6 of the charged power is provided in the power supply path. The secondary battery 1 is connected to a measuring unit 12 for measuring various information such as internal current and voltage.

[0041] The charging control device for controlling charging while performing suppression control during charging includes a communication unit 15, a resistance acquisition unit 17, a control unit 18, and a storage unit 19. The charging control device includes a processor such as a CPU, and each functional block of the charging control device is controlled by the processor. When the charging control device starts charging the secondary battery 1, the charging control including suppression control is started ( Figure 2 Step #1).

[0042] The communication unit 15 acquires information from the outside. For example, the communication unit 15 acquires the charging current 6 from the ammeter 11 over time, and stores each charging current 6 in association with the acquisition time in the storage unit 19 ( Figure 2 Step #2). In addition, the communication unit 15 acquires information such as the current and voltage of the secondary battery 1 measured by the measurement unit 12 over time, and stores each battery information 21 in the storage unit 19 as battery information 21 associated with the acquisition time.

[0043] The resistance acquisition unit 17 obtains the internal resistance 5 ( Figure 2 The resistance acquisition unit 17 stores the obtained internal resistance 5 in the storage unit 19 in association with the time when the battery information 21 is acquired.

[0044] The resistance acquisition unit 17 may also obtain the internal resistance 5 by any method, for example, the internal resistance 5 may be calculated based on the current and voltage of the secondary battery 1 obtained as the battery information 21. In addition, a table that specifies the relationship between any battery information 21 and the internal resistance 5 may be prepared in advance, and the resistance acquisition unit 17 may obtain the internal resistance 5 based on the table according to the battery information 21. In addition, the internal resistance 5 of the secondary battery 1 may be directly measured by the measuring unit 12, and the resistance acquisition unit 17 may obtain the internal resistance 5 measured by the measuring unit 12 over time via the communication unit 15.

[0045] The control unit 18 controls the electric power supplied from the power source 3 to the secondary battery 1. Specifically, the control unit 18 performs suppression control for controlling the electric power supplied from the power source 3 during charging based on the charging current 6, the internal resistance 5, and the threshold value 8.

[0046] Specifically, first, the control unit 18 obtains the charging current 6 and the internal resistance 5 stored in the storage unit 19, and calculates the product (IR) of the charging current 6 and the internal resistance 5 at a certain time during the charging period ( Figure 2 Step #4).

[0047] Next, the control unit 18 obtains the threshold value 8 stored in advance in the storage unit 19, and determines whether the product (IR) of the charging current 6 and the internal resistance 5 is greater than the threshold value 8 ( Figure 2 Step #5).

[0048] When IR is greater than the threshold value 8 ( Figure 2 Step #5: Yes), the control unit 18 performs suppression control ( Figure 2 The suppression control is a control for suppressing at least one of the charging current 6 and the internal resistance 5 so that the IR becomes less than the threshold value 8.

[0049] When IR is below the threshold value of 8 ( Figure 2 Step #5: No), or when performing inhibitory control ( Figure 2 In step #6), the control unit 18 determines whether the charging (charging control) is completed ( Figure 2 Step #7). When charging (charging control) is completed ( Figure 2 Step #7: Yes), end the process, if charging is not completed ( Figure 2 Step #7: No), the process returns to the calculation of the IR at the next specified time ( Figure 2 4) and continue charging.

[0050] As described above, the value of the product (IR) of the charging current 6 and the internal resistance 5 of the secondary battery 1 during charging is controlled using the threshold value 8 obtained by taking into account the allowable overvoltage when charging the secondary battery 1. As a result, it is possible to directly control the IR, which is mainly the battery voltage (CCV) during charging, so as not to exceed the allowable overvoltage. As a result, it is possible to easily suppress charging, thereby suppressing the degradation of the secondary battery 1.

[0051] [Inhibitory Control]

[0052] Next, use Figure 1 , Figure 2 A specific configuration example of the suppression control will be described. As described above, the suppression control is a control for suppressing at least one of the charging current 6 and the internal resistance 5 .

[0053] When controlling the charging current 6, the control unit 18 controls the power source 3 so that the value of the product of the charging current 6 and the internal resistance 5 (IR) becomes less than the threshold value 8, that is, so that the charging current 6 ≤ the threshold value 8 / the internal resistance 5 ( Figure 2 Step #6-1).

[0054] When controlling the internal resistance 5, the internal resistance 5 may be controlled by any method. For example, the internal resistance 5 of the secondary battery 1 depends on the temperature of the secondary battery 1. Therefore, the control unit 18 may also control (suppress) the internal resistance 5 and perform charging control by controlling the temperature of the secondary battery 1 during charging (charging temperature 28). Figure 2 Step #6-2).

[0055] In order to control the internal resistance 5 by controlling the temperature of the secondary battery 1, a temperature adjustment unit 24 is provided for the secondary battery 1. The temperature adjustment unit 24 controls the temperature (charging temperature 28) of the secondary battery 1. In addition, the charging control device includes a temperature control unit 26. Furthermore, the measuring unit 12 continuously measures the temperature of the secondary battery 1 during charging as the battery information 21, and the communication unit 15 acquires the temperature of the secondary battery 1 measured by the measuring unit 12, and stores the temperature as the charging temperature 28 in the storage unit 19.

[0056] In such a configuration, when controlling the internal resistance 5, the control unit 18 controls (changes) the charging temperature 28 so that the value of the product (IR) of the charging current 6 and the internal resistance 5 becomes less than the threshold value 8, that is, so that the internal resistance 5 ≤ threshold value 8 / charging current 6. Specifically, the control unit 18 controls the temperature adjustment unit 24 via the temperature control unit 26 to increase the charging temperature 28 of the secondary battery 1 to reduce the internal resistance 5. The control of the charging temperature 28 is performed by any method. For example, when the IR exceeds the threshold value 8, the control unit 18 (temperature control unit 26) may increase the charging temperature 28 by a predetermined temperature or a predetermined ratio relative to the current charging temperature 28. Alternatively, a table indicating the relationship between the internal resistance 5 and the charging temperature 28 may be prepared in advance, and the control unit 18 (temperature control unit 26) may control the secondary battery 1 to a charging temperature 28 corresponding to the internal resistance 5 so that the IR becomes less than the threshold value 8.

[0057] [Threshold]

[0058] Next, use Figure 1 , Figure 3 Next, a configuration example for setting (determining) the threshold value 8 will be described. However, the threshold value 8 is not limited to being set by the following method, and can be set by any method.

[0059] When the charge control device sets the threshold 8, the charge control device includes a threshold setting unit 31. The threshold setting unit 31 determines (sets) the threshold 8 by changing the conditions of the power to be charged, such as IR, and the conditions of discharge, and checking the tendency of the battery performance of the secondary battery 1 to decrease while repeating charge and discharge.

[0060] In addition, the threshold value 8 is usually set when the secondary battery 1 is not in use.

[0061] Specifically, first, the threshold setting unit 31 receives the setting input of the charge and discharge conditions consisting of the upper and lower limit voltages and the discharge current during charge and discharge ( Figure 3 The threshold setting unit 31 repeats charging and discharging under the charging and discharging condition, and the charging and discharging condition is not changed.

[0062] Next, the threshold setting unit 31 sets the initial charging current 6 and the internal resistance 5 (the product of the charging current 6 and the internal resistance 5) during charging as the IR condition ( Figure 3 Step #2 of ). Here, as the IR condition when n=0, the threshold setting unit 31 sets the initial charging current 6 to the charging current I(0) and the initial internal resistance 5 to the internal resistance R(0). Then, under the charging and discharging condition and the IR condition, the secondary battery 1 is repeatedly charged and discharged a predetermined number of times. The predetermined number of times is one or more times predetermined.

[0063] Next, the threshold setting unit 31 obtains the charging efficiency 33 based on the battery information 21 measured by the measuring unit 12 and stored in the storage unit 19 every time charging and discharging is performed, and stores the charging efficiency 33 in the storage unit 19 ( Figure 3 Here, the threshold setting unit 31 can obtain one or more indicators represented by the AH efficiency which is the difference (ratio) between the amount of charged power and the amount of dischargeable power, the difference (ratio) between the charge capacity and the discharge capacity, etc. as the charging efficiency 33.

[0064] Next, the threshold setting unit 31 determines whether the charging efficiency 33 has a decreasing trend of more than a predetermined value, that is, whether the charging efficiency 33 has decreased by a predetermined value (predetermined value) or a predetermined ratio (decreasing rate first reference value) or more ( Figure 3 Step #4).

[0065] Next, when the charging efficiency 33 has no tendency to decrease ( Figure 3 Step #4: No), the threshold setting unit 31 changes the IR condition, repeats the charge and discharge again, and repeats the process of obtaining the charging efficiency 33 ( Figure 3 Step #3) and subsequent steps ( Figure 3 Step #5 of ). Specifically, the threshold setting unit 31 increases the value of at least one of the charging current 6 and the internal resistance 5. That is, the threshold setting unit 31 increases n by 1 and sets the charging current I(n) and the internal resistance R(n) so that I(n)×R(n)>I(n-1)×R(n-1). For example, when charging and discharging are performed under the initial IR condition and the charging efficiency 33 has no tendency to decrease, the threshold setting unit 31 sets the charging current I1 and the internal resistance R1 so that I1×R1>I0×R0.

[0066] In addition, one of the charging current I(n) and the internal resistance R(n) may be increased compared to the charging current I(n-1) or the internal resistance R(n-1), or both the charging current I(n) and the internal resistance R(n) may be increased compared to the charging current I(n-1) and the internal resistance R(n-1), and it is sufficient to increase the product of the charging current 6 and the internal resistance 5. In order to avoid unbalanced increase of only one side when only one side is increased, the threshold setting unit 31 preferably increases the charging current 6 and the internal resistance 5 in an appropriately distributed manner, such as by alternately increasing the charging current 6 and the internal resistance 5 each time the IR condition is changed.

[0067] In addition, the value to be increased may be always fixed, or the increase range may be gradually reduced, or the increase range may be changed according to the degree of reduction in the charging efficiency 33. For example, the threshold setting unit 31 may initially increase at least one of the charging current 6 and the internal resistance 5 at a fixed ratio (value), and when the charging efficiency 33 decreases to a predetermined ratio or value (second reference value) greater than the first reference value, the value to be increased may be reduced.

[0068] Then, when the charging efficiency 33 tends to decrease ( Figure 3 Step #4: Yes), the threshold setting unit 31 sets the product of the charging current 6 and the internal resistance 5 at this time as the threshold 8 ( Figure 3 Step #6 of ). Thus, the state where the charging efficiency 33 deteriorates beyond the allowable range due to overvoltage can be set as the threshold 8 corresponding to the reduction (deterioration) of the battery performance of the secondary battery 1, and the degradation of the secondary battery 1 can be easily and accurately determined.

[0069] [Other embodiments]

[0070] (1) In the above embodiment, the suppression control is not limited to the structure based on the threshold value 8, and the suppression control may also be performed in consideration of the capacity maintenance rate 35 of the secondary battery 1. For example, since the overvoltage allowed for the secondary battery 1 depends on the capacity of the secondary battery 1, the overvoltage allowed for the secondary battery 1 changes in proportion to the capacity degradation of the secondary battery 1. Therefore, the control unit 18 controls the power supply 3 in such a way that the value of the product (IR) of the charging current 6 and the internal resistance 5 becomes less than the product of the threshold value 8 and the capacity maintenance rate 35 (suppression control).

[0071] In order to obtain the capacity maintenance rate 35, the charging control device includes a capacity maintenance rate acquisition unit 36. In addition, the charging capacity of the secondary battery 1 in an unused state is stored in advance in the storage unit 19 as the initial full charge capacity 38. The capacity maintenance rate acquisition unit 36 ​​acquires the full charge capacity 39 of the secondary battery 1, and obtains the capacity maintenance rate 35 by dividing the initial full charge capacity 38 by the full charge capacity 39. In addition, the capacity maintenance rate acquisition unit 36 ​​may obtain the capacity maintenance rate 35 obtained in another way from the outside via the communication unit 15.

[0072] With such a configuration, the threshold value 8 is corrected based on the capacity maintenance rate 35 according to the degradation of the secondary battery 1 , and the suppression control is performed based on the corrected threshold value 8 , so that the degradation of the battery performance during charging can be suppressed with higher accuracy.

[0073] Here, using the graph, Figure 4 To illustrate the effect of inhibitory control. Figure 4 The data are experimental data showing the degree of degradation of the secondary battery 1 when charge and discharge are repeated.

[0074] exist Figure 4 In the figure, the horizontal axis represents the total discharge capacity, which corresponds to the number of charge and discharge times (the amount of the secondary battery 1 used). The vertical axis represents the capacity maintenance rate 35 of the secondary battery 1. In addition, the triangular mark represents the data when charging without suppressing control, the square mark represents the data when charging while suppressing control is performed, and the circular mark represents the data when charging while suppressing control is performed in consideration of the capacity maintenance rate 35.

[0075] As from Figure 4 It can be seen that when the suppression control is not performed, the capacity maintenance rate 35 decreases from an early stage and decreases significantly. In contrast, by performing the suppression control, the decrease in the capacity maintenance rate 35, that is, the degradation of the secondary battery 1 is suppressed. In addition, it can be seen that by performing the suppression control in consideration of the capacity maintenance rate 35, the degradation of the secondary battery 1 is further suppressed.

[0076] (2) In each of the above embodiments, the internal resistance 5 changes according to the temperature, so the resistance acquisition unit 17 can perform temperature correction on the obtained (acquired) internal resistance 5. Specifically, the resistance acquisition unit 17 prepares a table showing the relationship between the charging temperature 28 and the temperature variation coefficient of the internal resistance 5 in advance, acquires the coefficient from the table based on the charging temperature 28, and corrects the internal resistance 5 using the acquired coefficient.

[0077] Alternatively, a table in which the relationship between the charging temperature 28 and the internal resistance 5 is obtained in advance through experiments may be prepared, and the resistance acquisition unit 17 may acquire the internal resistance 5 from the table based on the charging temperature 28 .

[0078] By determining the internal resistance 5 in consideration of the charging temperature 28 in this manner, the internal resistance 5 can be determined with higher accuracy, and degradation of battery performance during charging can be suppressed with higher accuracy.

[0079] (3) In each of the above embodiments, suppression control may be performed all the time while the secondary battery 1 is being charged, but suppression control may be performed only during a specified period during charging, for example, during the second half of charging. Specifically, during charging, when the charging voltage 41 or the charging capacity exceeds a specified value (upper limit voltage or upper limit capacity), the control unit 18 performs suppression control as follows: at least one of the charging current 6 and the internal resistance 5 is controlled so that the product (IR) of the charging current 6 and the internal resistance 5 does not exceed the threshold value 8 (or the product of the threshold value 8 and the capacity maintenance rate 35). In this case, the charging voltage 41 is measured by the measuring unit 12 (equivalent to the voltage measuring unit), and the charging voltage 41 is obtained via the communication unit 15 and stored in the storage unit 19. In addition, the control unit 18 may perform suppression control based on the threshold value 8 determined for each range when the charging voltage 41 or the charging capacity is within one or more specified ranges. For example, a plurality of charging voltage segments 42 are determined according to the value of the charging voltage 41, and a unique threshold value 8 is set for each charging voltage segment 42. Then, when the charging voltage 41 reaches the voltage corresponding to the charging voltage range 42 , the control unit 18 performs suppression control using the threshold value 8 corresponding to the charging voltage range 42 .

[0080] like Figure 5 As shown in FIG. 4 , when charging is performed with a fixed charging current 6, the charging voltage 41 increases as charging proceeds. Figure 5 In the example shown, suppression control is performed from the initial stage of charging by suppressing the charging current 6. At this time, CC (Constant Current) charging is performed at the beginning of charging, and when the charging voltage 41 reaches the upper limit voltage of the secondary battery 1 at time t0, the charging method is changed to CV (Constant Voltage) charging, and then charging is terminated.

[0081] Charging can also be terminated after reaching the upper limit voltage without CV charging. Figure 5 and the following Figure 6 , Figure 7 4 is a diagram showing changes in the charging current 6 and the charging voltage 41 during the charging period.

[0082] exist Figure 5 to Figure 7 In FIG. 4 , the horizontal axis represents the elapsed time of charging, and the vertical axis represents the charging current 6 and the charging voltage 41. Figure 6 , Figure 7 In the example shown, Figure 5Similarly to the example shown, CC charging may be performed at the beginning of charging, and after the charging voltage 41 reaches the charging upper limit voltage, the charging may be switched to CV charging, or only CC charging may be performed.

[0083] like Figure 6 As shown, the control unit 18 can set the range for suppression control by the switching voltage VR of the charging voltage 41. That is, the control unit 18 performs suppression control in the range (charging voltage section 42) where the charging voltage 41 is greater than the switching voltage VR during charging. Here, the switching voltage VR is the upper limit charging voltage or a voltage that is smaller than the upper limit charging voltage by a predetermined margin.

[0084] exist Figure 6 In the above, at time t1, the charging voltage 41 exceeds the switching voltage VR. Therefore, after time t1, the charging voltage section 42 is formed, and the control unit 18 performs suppression control by suppressing the charging current 6 using the threshold value 8 obtained by taking the switching voltage VR into consideration in the charging voltage section 42. When the charging voltage 41 reaches the charging upper limit voltage at time t2 in the charging voltage section 42, the charging is switched to CV charging, and when IR exceeds the threshold value 8, the suppression control is performed by suppressing the charging current 6.

[0085] The plurality of charging voltage segments 42 are set by using a plurality of switching voltages VR. Figure 7 In the example, the charging voltage 41 exceeds the switching voltage VA at time t3. Therefore, after time t3, the charging voltage segment 42A is formed, and the control unit 18 performs suppression control by using a predetermined threshold value 8A in the charging voltage segment 42A to suppress the charging current 6. Furthermore, the charging voltage 41 exceeds the switching voltage VB at time t4. Therefore, after time t4, the charging voltage segment 42B is formed, and the control unit 18 performs suppression control by using a threshold value 8B different from the threshold value 8A in the charging voltage segment 42B to suppress the charging current 6. At this time, when the charging voltage 41 exceeds the upper limit charging voltage (time t5), it is converted to CV charging, and when IR exceeds the threshold value 8, suppression control is performed by suppressing the charging current 6. In addition, the margins of the threshold values ​​8A and 8B relative to the upper limit charging voltage are different.

[0086] (4) In the above-mentioned embodiments, the charging control device is not limited to Figure 1The device composed of the functional blocks shown may also be composed of arbitrary functional blocks. For example, the functional blocks of the charging control device may be further subdivided, and conversely, part or all of the functional blocks may be combined. In addition, the functions of the charging control device are not limited to the above-mentioned functional blocks, and may also be implemented by a method executed by an arbitrary functional block. In addition, part or all of the functions of the charging control device may also be composed of software. Programs related to the software are stored in an arbitrary storage device such as the storage unit 19, and are executed by a processor (computer) such as a CPU of the charging control device or a separately arranged processor (computer). For example, part or all of the processing of the program may also be executed by a processor mounted on a device such as a server that is separately arranged from the charging control device.

[0087] In addition, the structure disclosed in the above-mentioned embodiment (including other embodiments, the same below) can be combined and applied with the structure disclosed in other embodiments as long as no contradiction occurs. In addition, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these and can be appropriately changed within the scope of the purpose of the present invention.

[0088] Industrial Applicability

[0089] The present invention can be applied to a charging control device that controls charging of a secondary battery.

[0090] Description of Reference Numerals

[0091] 1: Secondary battery; 3: Power supply; 5: Internal resistance; 6: Charging current; 8: Threshold value; 12: Measuring unit (voltage measuring unit); 17: Resistance acquisition unit; 18: Control unit; 19: Storage unit; 21: Battery information; 26: Temperature control unit; 35: Capacity maintenance rate; 36: Capacity maintenance rate acquisition unit; 38: Initial full charge capacity; 41: Charging voltage; 42: Charging voltage range.

Claims

1. A charging control device for controlling charging of a secondary battery by supplying electric power from a power source, the charging control device comprising: a control unit that controls the electric power supplied from the power source; and a resistance acquisition unit for obtaining an internal resistance of the secondary battery, in, The power source can supply the electric power to the secondary battery in a manner capable of changing the charging current. The control unit performs suppression control of the power supply so that a product of the charging current and the internal resistance becomes equal to or less than a predetermined threshold value.

2. The charging control device according to claim 1, wherein: The threshold value is set in consideration of an overvoltage that can be allowed when charging the secondary battery.

3. The charging control device according to claim 2, wherein: The product of the charging current and the internal resistance is varied through experiments and charging and discharging are repeated. The charging efficiency or the rate of decrease in full charge capacity is measured each time charging and discharging is performed. The product of the charging current and the internal resistance when the rate of decrease in the charging efficiency or the full charge capacity is less than a specified value is determined as the threshold value.

4. The charging control device according to claim 1, wherein: further comprising a temperature control unit for controlling the temperature of the secondary battery during charging, The control unit controls the internal resistance by controlling the temperature of the secondary battery by the temperature control unit so that the product of the charging current and the internal resistance becomes equal to or less than the threshold value during the suppression control.

5. The charging control device according to claim 1, wherein: Also available: a storage unit that stores an initial full charge capacity of the secondary battery; and a capacity maintenance rate acquisition unit for obtaining a capacity maintenance rate of the secondary battery based on the initial full charge capacity, The control unit performs the suppression control so as to be equal to or less than a product of the threshold value and the capacity maintenance rate.

6. The charging control device according to any one of claims 1 to 5, wherein: further comprising a voltage measuring unit for measuring a charging voltage during charging, The control unit performs the suppression control when the charging voltage is a predetermined upper limit voltage.

7. The charging control device according to any one of claims 1 to 5, wherein: further comprising a voltage measuring unit for measuring a charging voltage during charging, Setting a different threshold for each of a plurality of charging voltage segments, The control section performs the suppression control using the threshold value corresponding to each of the charging voltage steps.

8. A charging control method for controlling charging of a secondary battery by supplying electric power from a power source, the charging control method comprising the following steps: Calculating the internal resistance of the secondary battery; and The power supply is controlled so that the product of the charging current of the power and the internal resistance becomes equal to or less than a predetermined threshold value.

9. A charging control program for controlling charging of a secondary battery by supplying electric power from a power source, the charging control program causing a computer to execute the following functions: Calculating the internal resistance of the secondary battery; and The power supply is controlled so that the product of the charging current of the power and the internal resistance becomes equal to or less than a predetermined threshold value.

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