Charging method for an energy storage unit consisting of a capacitor secondary battery

Abstract

To provide a charging method capable of sufficiently exhibiting each power storage capacity even if there is difference in power storage capacity of a power storage unit on the premise that a capacitor is used as a power storage element and there are variations in the power storage elements constituting the power storage unit and a combination thereof.SOLUTION: A charging method of a power storage unit is configured by connecting a power storage element group composed of capacitors in series, parallel, or series-parallel. After a voltage between terminals of constituting power storage element groups of the power storage unit is measured, and after a known charge Q is supplied to all the power storage element groups, a voltage between terminals of each power storage element group is measured, the power storage element group having the largest voltage change amount is specified, a charge amount until the power storage element group having the lowest power storage capability is fully charged is calculated, and after the power storage unit is charged up to the charge amount, charging operation is completed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , , , ,

[0001] The present invention relates to a charging method for a charging system using a storage element.

Background Art

[0002] Rechargeable storage elements such as lithium-ion batteries have rapidly spread in recent years and are used in various fields. For example, in mobile phones, notebook computers, electric vehicles (EVs), electric assist bicycles, etc., they have become an essential device without which people can no longer do without in their daily and social lives.

[0003] In the future, not only ground mobility but also the development of various forms of mobility fields such as air mobility is expected. Also, as a countermeasure against global warming caused by carbon dioxide emissions, a power storage device is required to stabilize power supply by charging with power from natural energy such as solar power generation and wind power generation with low stability during surplus times and discharging during deficit times. Furthermore, in order to expand the application to various robots and humanoid working robots that can realize the automation of factories and production lines to improve the quality of life (QOL) for people to live comfortably while preparing for the rapid aging and population decline in the future, the storage element and the power storage unit using it are required to realize further miniaturization, higher capacity, rapid and high-current charge and discharge, longer life, and ease of handling. As a result, it is clear that they will be used in a wider range of fields than before. Based on these considerations, various forms have been proposed for the charging equipment of the above-mentioned EV power storage elements to enable faster charge and discharge than before (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] The aforementioned energy storage unit is generally composed of a group of energy storage elements formed by connecting multiple energy storage elements in series, parallel, or series-parallel, and further connecting these combinations in series, parallel, or series-parallel as needed. The energy storage device is configured by further connecting these energy storage units in series, parallel, or series-parallel as needed.

[0006] In the case of energy storage elements, primarily secondary batteries, that are currently in practical use, there are two major problems: firstly, problems related to charging and discharging, mainly due to variations in the storage capacity, internal resistance, leakage current, and allowable output current of each energy storage element; and secondly, constraints related to handling the energy storage elements in actual use, such as the operating temperature range, output response time, number of charge / discharge cycles and lifespan, degradation of element characteristics, and limitations on the maximum and minimum voltages during use.

[0007] The first problem here is that it is virtually impossible for the individual energy storage elements, which are the smallest units that make up an energy storage unit, to have the same values ​​for output voltage, storage capacity, etc. This is because the amount of energy stored by each individual energy storage element generally varies within a certain range, and the distribution of this variation is due to the accumulation of differences in the materials and components that make up the energy storage element, the environment of each manufacturing process, the equipment group, the manufacturing line, etc. As a result, each energy storage unit generally has slightly different characteristics. Therefore, it is quite difficult to minimize the deviation in the rechargeable storage capacity and output voltage values ​​of the energy storage elements of the finished energy storage unit and its individual components.

[0008] Therefore, the current practice involves measuring the finished energy storage elements to determine their variability, dividing them into multiple groups to ensure they fall within a predetermined range, and then combining them in a way that minimizes deviations in variability. This requires extra effort and man-hours to ensure that the variability within a series-or series-parallel connected group of energy storage elements falls within a predetermined range. As a result, it is difficult to improve the production efficiency of energy storage units and to reduce costs.

[0009] Thus, in addition to the considerable effort required to eliminate variations in the finished product, there is an inherent problem in that it is extremely difficult to predict phenomena such as aging and degradation associated with the type and specifications of the energy storage elements.

[0010] Next, regarding the second issue, most of the energy storage devices currently in widespread use are rechargeable secondary batteries, and all of these secondary batteries utilize chemical reactions.

[0011] Therefore, it is an energy storage element that inherently has problems such as: (1) there are upper and lower limits to the operating temperature range; if the temperature is too high the reaction proceeds too quickly and is damaged by overheating, and if the temperature is too low the reaction does not proceed and it does not function as a battery; (2) because electricity is generated by a chemical reaction there is a limit to the response time and it is difficult to respond to sudden increases or decreases in current; (3) because extra products are produced during the chemical reaction, the performance gradually deteriorates with repeated charging and discharging, so there is a limit to the number of charge and discharge cycles; (4) there is a lower limit to the output voltage of the battery, and if the voltage drops below that, it will cease to function as a battery, that is, it will lose its function as a battery; therefore, it is necessary to perform regular inspections and charge it when necessary.

[0012] Furthermore, while the performance of secondary batteries gradually deteriorates with repeated charging and discharging, it is difficult to predict the extent of this deterioration in advance. Moreover, as they are used, the characteristics of each energy storage element also deteriorate, and the deviations between them increase. From the perspective of future applications of energy storage elements in various fields, current secondary batteries still have problems that need to be solved, but are difficult to solve.

[0013] The objective of the present invention is to provide a charging method for a capacitor secondary battery that uses a large-capacity capacitor (hereinafter referred to as a capacitor), which now has capacitive capacitances exceeding tens of thousands of F, as an energy storage element to provide a function similar to that of a secondary battery (hereinafter referred to as a capacitor secondary battery), and also to enable the energy storage capacity of each energy storage unit to be fully utilized even if there are individual differences in the energy storage capacity of the energy storage unit and the individual energy storage elements, given that there are individual differences in the energy storage capacity of the energy storage unit and the individual energy storage elements that make up the energy storage unit.

[0014] Furthermore, the charging method of the present invention can also be applied to conventional secondary battery charging methods. [Means for solving the problem]

[0015] To solve the above-mentioned problems, the present invention proposes a new charging method that treats large-capacity capacitors (hereinafter referred to as capacitors), some of which have capacities exceeding tens of thousands of F, as energy storage elements with the same functionality as secondary batteries (hereinafter referred to as capacitor secondary batteries), and that tolerates variations in the various characteristics of so-called energy storage elements, including capacitors and conventional secondary batteries.

[0016] A method for charging an energy storage unit comprising a capacitor secondary battery according to claim 1 of the present invention is: A method for charging a capacitor secondary battery, which consists of a single energy storage element made of a capacitor, or a group of multiple energy storage elements, m sets (where m is a natural number), connected in series, parallel, or series-parallel, wherein the unit is configured by further connecting these m sets in series, parallel, or series-parallel, Step S1 involves measuring the terminal voltages for each of the first to n (where n is a natural number greater than or equal to 2) groups of energy storage elements that constitute the energy storage unit. Step S2 involves accumulating charge δQ for each group of energy storage elements by flowing a predetermined charge δQ through the first to nth groups of energy storage elements connected in series in order to identify the group of energy storage elements with the smallest energy storage capacity among the aforementioned groups of energy storage elements. Step S3 involves measuring the terminal voltage of each energy storage element group after the charge δQ has been applied to each energy storage element group in accordance with step S2. Step S4 calculates the change in the terminal voltage measured in step S3 at the time of charge capacity determination for each group of energy storage elements, and the change in the terminal voltage measured in step S1. In step S4, among the terminal voltages calculated for each group of energy storage elements, the group with the largest change, that is, the group of energy storage elements with the lowest energy storage capacity, is identified. If, under these conditions, it is determined that the group of energy storage elements with the lowest energy storage capacity cannot be identified, and the number of repetitions of steps S2 to S5 is less than a predetermined number, step S5 involves storing the terminal voltage information of the group of energy storage elements, adding 1 to the number of repetitions, and then returning to step S2. If the number of repetitions exceeds a predetermined number, step S5 terminates the charging operation according to this procedure. Step S6 involves estimating and calculating the amount of charge required for that group of energy storage elements to reach full charge, based on the aforementioned information identifying the group of energy storage elements with the lowest energy storage capacity. The present invention is characterized by having step S7, in which the amount of charge calculated in step S6 is applied to the energy storage unit, and once that is complete, the charging operation of the energy storage unit is completed.

[0017] Furthermore, the method for charging a power storage unit consisting of a capacitor secondary battery according to claim 2 of the present invention is: A method for charging an energy storage unit consisting of a capacitor secondary battery as described in claim 1, A charging method for a capacitor secondary battery, comprising performing a basic charge as described in claim 1 followed by a further first supplemental charge, wherein after the basic charge is completed, the group of energy storage elements that are not yet fully charged are identified by measuring the voltage between their terminals, and these identified energy storage elements requiring the first supplemental charge are fully charged until all of them are fully charged, at which point the first supplemental charge is completed. It is characterized by this fact.

[0018] Furthermore, the method for charging a power storage unit consisting of a capacitor secondary battery according to claim 3 of the present invention is: A method for charging an energy storage unit consisting of a capacitor secondary battery as described in claim 1, A charging method for a capacitor secondary battery energy storage unit, wherein, after performing the basic charge described in claim 1, a second supplementary charge is performed to fully charge the group of energy storage elements when the charge amount of the group of energy storage elements decreases due to self-discharge or leakage current, and this second supplementary charge is performed by identifying the group of energy storage elements with the least amount of charge by measuring the voltage between each terminal and individually charging them as a priority, or by individually charging the groups of energy storage elements in order of decreasing remaining charge. It is characterized by this fact.

[0019] Furthermore, the method for charging a power storage unit according to claim 4 of the present invention is: This system is characterized in that each energy storage element constituting the aforementioned energy storage element group is a chemical secondary battery instead of a capacitor. [Effects of the Invention]

[0020] According to the present invention, even if there are variations in each of the power storage elements that are components of the power storage unit and the groups of power storage elements combined therefrom, resulting in individual differences in the power storage capacity of the power storage unit, it is possible to provide a charging method for a power storage unit composed of a capacitor secondary battery that can fully exhibit the power storage capacity possessed by each power storage unit.

Brief Description of the Drawings

[0021] [Figure 1] It is an explanatory diagram showing a schematic configuration of a power storage unit according to an embodiment of the present invention. [Figure 2] It is a flowchart for explaining a basic charging method of a power storage unit according to an embodiment of the present invention shown in FIG. 1. [Figure 3] It is a flowchart for explaining Supplementary Charging 1 for individually charging each power storage element group constituting the power storage unit following FIG. 2. [Figure 4] It is a flowchart for explaining Supplementary Charging Method 2 for individually charging some or all of the power storage element groups constituting the power storage unit following FIG. 2, which is different from the flowchart shown in FIG. 3. [Figure 5] It is a characteristic diagram (FIG. 5(a)) showing the relationship between the voltage and the charge amount of each power storage element group constituting the power storage unit when the power storage element of the present invention is a capacitor, and a characteristic diagram (FIG. 5(b)) showing the relationship between the voltage and the charge amount of each power storage element group constituting the power storage unit when the power storage element of the present invention is a power storage element composed of a secondary battery.

Modes for Carrying Out the Invention

[0022] The following describes a charging method for a power storage unit consisting of a capacitor secondary battery according to one embodiment of the present invention, based on the drawings. Although the power storage element used in the power storage unit according to this embodiment (hereinafter simply referred to as "power storage unit" as appropriate) is a large-capacity capacitor, in the following description, in order to unify terminology, facilitate understanding of the explanation, and emphasize the advantages of the present invention, the term "capacitor" will be used consistently instead of "condenser". In addition, the term "power storage element group" will be used as the basis, but in some cases the term "capacitor group" will be used. Furthermore, the power storage unit may also be referred to as a "capacitor power storage unit".

[0023] Figure 1 is an explanatory diagram showing the schematic configuration of an energy storage unit according to one embodiment of the present invention. As is clear from Figure 1, this energy storage unit comprises multiple capacitor groups, each consisting of capacitors connected in parallel, and these capacitor groups are connected in series. More specifically, as shown at the top of this drawing, the first capacitor group C1 comprises capacitors C1-1, C1-2, C1-3, ... C1-a (where a is a natural number of 2 or more and may differ for each stage) connected in parallel. Although a is specified as a natural number of 2 or more, it should be noted that the effects of the present invention can be achieved even if a=1 in some cases, and this is included within the scope of the present invention.

[0024] Similarly, the second capacitor group C2 is comprised of capacitors C2-1, C2-2, C2-3, ..., C2-b (where b is a natural number greater than or equal to 2) connected in parallel.

[0025] Similarly, as shown at the bottom of this diagram, the nth capacitor group Cn (where n is a natural number greater than or equal to 2) is configured by connecting capacitors Cn-1, Cn-2, Cn-3, ..., Cn-x (where x is a natural number greater than or equal to 2) in parallel. The first to the nth capacitor group are then connected in series to form a capacitor unit (energy storage unit) 100.

[0026] Furthermore, the fact that there are individual differences in the energy storage capacity of the energy storage unit 100 due to variations in each energy storage element, which is a component of the energy storage unit 100, and in groups of energy storage elements combined therefrom, is the same as what was explained in the section on the problems to be solved by the invention above.

[0027] In addition to the above, the energy storage unit 100 includes a centralized charging power supply unit 210, individual charging power supply units 220, and a voltage detection unit 250. Furthermore, it includes switches SWU, SWC, and SWD for opening and closing the circuit, placed in appropriate locations in the circuit, and a switch switching control unit 260 for controlling the opening and closing (continuity / disconnection, or on / off) of each of these switches. Here, SWU-1 and SWU-2 are referred to as SWU, SWD-1 and SWD-2 as SWD, SWD(y-1) and SWD(y-2) as SWD(y), and SWC(x-1) and SWC(x-2) as SWC(x), where x and y are natural numbers. In addition to these, it also includes a control unit that controls all of these, namely an energy storage unit control unit 200 for charging the energy storage unit 100 using the charging method unique to the present invention. Furthermore, the energy storage unit control unit 200 includes a switch switching control unit 260 and a charging mode selection unit 270 for selecting the optimal charging mode for the charging method unique to the present invention.

[0028] Furthermore, depending on the configuration of the energy storage unit 100, if the application target of the energy storage unit 100 is a vehicle or the like and requires the supply of a considerably large amount of power, then in addition to the above, a centralized charging power supply unit 210 or individual charging power supply units 220 may be provided separately from the energy storage unit 100. On the other hand, if the application target of the energy storage unit 100 is a household appliance or the like and does not require the supply of such a large amount of power, then all of the above-mentioned components may be integrated into the energy storage unit 100.

[0029] In other words, the aforementioned centralized charging power supply unit 210, individual charging power supply units 220, voltage detection unit 250, switch switching control unit 260, and the energy storage unit control unit 200 as a control unit for these may be provided in the energy storage unit 100 itself or configured as a separate unit, depending on the type of application of the energy storage unit 100.

[0030] The switch SW consists of multiple switches. Specifically, it includes a switch SWU (SWU-1, SWU-2) for supplying current from the central charging power supply unit 210 to the entire energy storage unit 100 for charging, a switch SWC(z) (where z is an integer from 1 to n) for switching the target of charging in order to supply current from the individual charging power supply unit 220 to only the terminal groups of each energy storage terminal group Cz selected from the energy storage element groups C1-1~a, C2-1~b, C3-1~c, ... Cn-1~x, and a switch for each energy storage element group C1-1~C1-a (hereinafter referred to as C1) It consists of a switch SWD (SWD-1 and SWD-2) for measuring the voltage when the capacitor group C1, C2, C3, ..., Cn-1, Cn-x (hereinafter referred to as Cn) is connected in series, or a switch SWD(y) (i.e., SWD(y-1) and SWD(y-2)) for selecting one of the energy storage element groups C1, C2, C3, ..., Cn-1, Cn (where y is an integer from 1 to n) and measuring the terminal voltage of the energy storage element group Cy with the voltage detection unit 250.

[0031] Furthermore, the circuits opened and closed by switches SWD and SWD(y) have a higher input resistance than circuits opened and closed by other switches, and care has been taken to reduce the effects during charging and other processes, so that the switches SWD can perform their intended function of voltage measurement.

[0032] Regarding the SWU switch, it functions as a switch to supply current from the centralized charging power supply unit 210 to each of the energy storage element groups C1, C2, C3, ..., Cn-1, Cn that make up the energy storage unit 100, while they are connected in series. As previously explained, it consists of SWU-1 and SWU-2. By closing (conducting) the SWU and SWD switches and opening (disconnecting) all the other switches (SWC(x) and SWD(x)), each of the energy storage element groups can be charged by the centralized charging power supply unit 210 while simultaneously measuring the terminal voltage. In other words, by supplying current from the centralized charging power supply unit 210 in this state, each of the energy storage element groups C1, C2, C3, ..., Cn-1, Cn can be charged at once, and their terminal voltages can also be measured.

[0033] Furthermore, the energy storage element group C1 is equipped with a switch SWC(1), i.e., SWC(1-1) and SWC(1-2), which supplies current from the individual charging power supply unit 220 only to this energy storage element group C-1. Similarly, the energy storage element group C2 is equipped with a switch SWC(2) which supplies current from the individual charging power supply unit 220 only to this energy storage element group, and the energy storage element group C3 is equipped with a switch SWC(3) which supplies current from the individual charging power supply unit 220 only to this energy storage element group.

[0034] Similarly, each energy storage element group Cn is equipped with a switch SWC(n) that supplies current only to this energy storage element group. In this way, each energy storage element group Cx (where x is an integer from 1 to n) is equipped with a pair of switches SWC(x), namely SWC(x-1) and SWC(x-2), that supply current between the terminals of the energy storage element group selected from the individual charging power supply unit 220.

[0035] Furthermore, each energy storage element group Cx (where x is an integer from 1 to n, and so on) is provided with a connection switch SWC(x) for connecting the energy storage element group Cx to the individual charging power supply unit 220 for charging, as well as connection switches SWD(x), i.e., SWD(x-1) and SWD(x-2), for connecting the terminal voltage of the same energy storage element group Cx to the voltage detection unit 250 for measuring the terminal voltage. The opening and closing control of these switches is performed by the switch switching control unit 260 within the energy storage unit control unit 200.

[0036] Then, by closing (opening) the switch SWC(x) corresponding to each energy storage element group Cx and charging the energy storage element group Cx with the individual charging power supply unit 220, while closing (opening) the voltage detection switch SWD(x) and opening (disabling) the switches other than SWC(x) and SWD(x), it is possible to charge only the energy storage element group Cx from the individual charging power supply unit 220 while simultaneously measuring the voltage between terminals.

[0037] Furthermore, the energy storage unit control unit 200, via the switch switching control unit 260, closes (connects) only the switches SWU, i.e., SWU-1 and SWU-2, and the switches SWD, i.e., SWD-1 and SWD-2, thereby charging the group of energy storage elements connected in series from the centralized charging power supply unit 210 via the switches SWU, and simultaneously connects the terminal voltage of the group of energy storage elements connected in series to the voltage detection unit 250, enabling the terminal voltage of the group of energy storage elements connected in series.

[0038] More specifically, the switch SWD used to measure the voltage when the energy storage elements are connected in series consists of SWD-1 and SWD-2, as previously explained. The switch SWD(x) used to measure the voltage of each energy storage element Cx individually consists of n sets of SWD(x-1) and SWD(x-2) (where x is a natural number from 1 to n), as previously explained.

[0039] When measuring the voltage of the energy storage element group Cx, the two switches SWD(x), namely SWD(x-1) and SWD(x-2), are closed to conduct electricity across both ends of the switches, while all other switches used for voltage detection, namely SWD(y) (where y is an integer from 1 to n other than x), are opened (disconnected). This allows the energy storage unit control unit 200 to measure the voltage value of the energy storage element group Cx using the voltage detection unit 250 when necessary.

[0040] Furthermore, when measuring the voltage with all the energy storage elements connected in series, the voltage can be measured using the voltage detection unit 250 by closing the switch SWD, i.e., SWD-1 and SWD-2, to conduct electricity across both ends of the switch and connect to the voltage detection unit 250, and by opening (disconnecting) another switch SWD(x) (where x is an integer from 1 to n) used for voltage detection.

[0041] As described above, by appropriately selecting the open (cut) and closed (conduct) states of multiple switches SWU, SWD, SWC(x), and SWD(x) (where x is an integer from 1 to n), when charging the selected group of energy storage elements Cx using the individual charging power supply unit 220, switches SWC(x) and SWD(x) are closed and all other switches are opened in order to simultaneously charge and measure the terminal voltage. Similarly, when charging the group of energy storage elements connected in series using the batch charging power supply unit 210, switches SWU and SWD are closed and all other switches are opened (released) in order to simultaneously charge the group of energy storage elements connected in series and measure the voltage. This makes it possible to accurately measure the voltage value by the voltage detection unit 250 while charging the selected group of energy storage elements.

[0042] Next, we will specifically explain the basic charging method of the energy storage unit according to the present invention shown in Figure 1. The charging method of the energy storage unit consisting of a capacitor secondary battery according to the present invention, which will be described below, has the advantage that even if there are variations in the characteristics of each group of energy storage elements (capacitor group) connected in parallel according to the present invention, or changes over time, the energy storage unit can be charged without overcharging even with the group of energy storage elements with the smallest storage capacity in the energy storage unit, by knowing the amount of energy that each group of energy storage elements can store in advance.

[0043] Figure 2 is a flowchart illustrating the basic charging method of an energy storage unit according to one embodiment of the present invention. Note that the energy storage element is a capacitor as shown in Figure 1, and the group of energy storage elements constitutes a capacitor unit; however, in the following explanation, these terms will be referred to as "energy storage element" and "group of energy storage elements," respectively. Specifically, the following procedure is followed to charge the energy storage unit.

[0044] First, the terminal voltage of each group of energy storage elements constituting the energy storage unit is measured (step S1). More specifically, when starting the routine for the basic charging method of the energy storage unit, for the switches shown in Figure 1, only switch SWD(1) (i.e., SWD(1-1) and switch SWD(1-2)) is closed (conductive state), and all other switches (SWD, SWU, SWC(x), SWD(x) (where x is an integer from 2 to n)) are opened (disconnected), and the terminal voltage V1 of the energy storage element group C1 is measured by the voltage detection unit 250.

[0045] Next, switch SWD(1) is opened and SWD(2) is closed, and the terminal voltage V2 of the energy storage element group C2 is measured by the voltage detection unit 250.

[0046] In this manner, the voltage of each energy storage element group at that time is measured for all energy storage element groups up to Cn. Note that the order in which the voltages of the energy storage element groups are measured does not have to be in the order from C1 to Cn as described above; they can be measured in any order.

[0047] Next, in order to estimate the storage capacity of each group of energy storage elements and identify the group of energy storage elements with the minimum storage capacity, a charge of δQ is introduced between the two electrodes of the energy storage module, which consists of a group of energy storage elements connected in series. As a result, the charge in each group of energy storage elements from C1 to Cn increases by δQ (Step S2).

[0048] Then, after the charge δQ in step S2 is applied to each group of energy storage elements, the terminal voltage of all the energy storage elements constituting the energy storage unit is measured again. In this voltage measurement, the terminal voltage of each group of energy storage elements after the charge δQ has been applied to each group of energy storage elements is measured using the same measurement method as in step S1, and the value is recorded in a memory element (not shown) provided in the energy storage unit control unit 200 (step S3).

[0049] The switch switching control unit 260 controls the combination of switching the aforementioned switches on and off to measure the voltage of each energy storage element group at this time.

[0050] Specifically, in step S3, the change in terminal voltage at the time of charge capacity determination is calculated in step S3 from the terminal voltage (before charge application) measured in step S1, and the change in ΔV1, ΔV2, ΔV3, ... ΔVn (where n is a natural number of 2 or more) is calculated in the energy storage unit control unit 200 for each group of energy storage elements (step S4).

[0051] Then, the group of energy storage elements with the smallest storage capacity (maximum voltage change) is identified based on the fluctuation of the terminal voltage of each energy storage element. If the voltage fluctuation value is too small to perform the above, or if it is determined that there is insufficient information because multiple pieces of information are needed to make the determination, the following processing is performed. Specifically, if the number of times δQ is assigned is within a preset upper limit, 1 is added to the number assigned and the process returns to step S2. If the number of times δQ is assigned exceeds the preset upper limit, this process is completed. Note that, as this is an abnormal processing, displaying information such as exceeding the numerical limit or recording information is optional (step S5).

[0052] Here, the change in the terminal voltage of each energy storage element group in this embodiment is a linear function of the voltage of the parallel-connected energy storage element group and the amount of charge possessed by each energy storage element group, as shown in the characteristic diagram of Figure 5(a).

[0053] In other words, when the energy storage element is a capacitor, the relationship Q = C·V holds between the amount of charge Q, the increased terminal voltage V, and the capacitance C of the connected group of energy storage elements. Therefore, the capacitance and the amount of charge or energy that can be charged for each group of energy storage elements connected in parallel can be easily calculated. Furthermore, the maximum and minimum capacitance of each group of energy storage elements can also be easily calculated. As a result, the allowable charge capacity of the entire energy storage unit can also be calculated.

[0054] Next, in order to calculate the amount of charge required to fully charge the group of energy storage elements with the smallest storage capacity, the amount of charge to be obtained is calculated as δQ × Vx ÷ ΔVi from the difference Vx between the maximum applied voltage of the capacitors constituting the group of energy storage elements and the maximum terminal voltage of each group of energy storage elements measured in step S4, and the voltage change value ΔVi of the group of energy storage elements with the smallest capacity (this value is also the largest value among the groups of energy storage elements). This is then calculated by the energy storage unit control unit 200. Note that the amount of charge is obtained by the product of the current value and the energizing time, so once the required amount of charge is determined and the current value to be supplied is determined, the energizing time can be obtained as required amount of charge ÷ current value (in seconds) (step S6).

[0055] Next, the charge calculated in the previous step is applied to the power terminals of the energy storage module, which consists of energy storage elements connected in series. The series-connected energy storage elements constituting the energy storage unit are given a charge of δQ × Vx ÷ ΔVi = Qmin, which was calculated earlier. Since the charge is the time integral of the current, if the current is constant, the charge is applied for a time calculated by Qmin ÷ current (A), and if the current fluctuates, the charge is applied until the time integral of the current equals Qmin. In this way, the basic charging shown in Figure 2 is completed via step S7. Once the charge has been applied to the energy storage module, charging is complete (step S7). In this way, the routine for basic charging is completed.

[0056] Next, a first supplementary charging method will be described, which, after completing the charging of the energy storage unit by steps S1 to S7 described above, further charges each of the energy storage elements constituting the energy storage unit individually to fully charge each energy storage unit.

[0057] The reason for introducing this supplemental charging method for the energy storage unit in this invention is as follows: Generally, even when fully charged, the charge stored in an energy storage element gradually decreases over time due to self-discharge and leakage current, and this value differs from component to component. Therefore, it is necessary to periodically fully charge the energy storage elements of the energy storage unit, either individually or in parallel connection units, or to a charge level predetermined by the energy storage unit, in order to reduce deviations in the energy storage element group caused by self-discharge and leakage current.

[0058] For the reasons stated above, the present invention provides a first supplementary charging method for the energy storage unit, which is a further energy storage process for the energy storage unit that takes these points into consideration, namely a charging method for the energy storage unit based on steps S10 to S13 to fully charge all energy storage elements. It also provides a second supplementary charging method for the energy storage unit based on steps S20 to S26, in which the group of energy storage elements with the lowest amount of stored energy is individually charged first, based on the self-discharge and leakage current described above, and then the groups of energy storage elements with the lowest amount of stored energy are individually charged in the order in which their remaining stored energy is decreasing. The invention makes it possible to selectively implement the first supplementary charging method and the second supplementary charging method depending on the charging time at the time and the intended use of the energy storage unit after charging.

[0059] Furthermore, the second replenishment charging method for the energy storage unit allows for the selection of an individual charging method for the energy storage elements, a so-called shortcut method, which shortens the charging time. This can be done by, for example, fully charging the energy storage elements in order from the lowest voltage side, or individually charging only the required number of energy storage elements in order from the energy storage elements with the least remaining charge.

[0060] Figure 3 is a flowchart of the first replenishment charging method for a power storage unit, which involves individually charging all the energy storage elements constituting the power storage unit shown in Figure 2. Note that, as with the explanation based on Figure 2 above, the explanation will assume the configuration of the power storage unit shown in Figure 1, where capacitors are used as the energy storage elements and a group of capacitors are used as the group of energy storage elements.

[0061] To initiate the first supplemental charging routine of this energy storage unit, if specified, one energy storage element Cx (where x is an integer from 1 to n) is selected from the specified group of energy storage elements, or arbitrarily (for example, in numerical order of the energy storage element group) if no specification is given, and at the same time, only the switches necessary to simultaneously measure the terminal voltage of the said energy storage element group Cx are closed (step S10).

[0062] Specifically, only the switches SWC(x) and SWD(x) corresponding to a particular group of energy storage elements Cx are closed, while the other switches, SWU, SWD, SWC(y), and SWD(y) (where y is an integer from 1 to n excluding x), are left open. In other words, all switches except those corresponding to the group of energy storage elements Cx are left open.

[0063] Next, current is passed through the selected group of energy storage elements Cx to charge them, and the terminal voltage is measured. Charging continues until the group of energy storage elements is fully charged. Once fully charged, charging is terminated, and the switches that were simultaneously measuring the terminal voltage are opened to disconnect the group of energy storage elements (step S11).

[0064] The system records that the charging of the selected group of energy storage elements is complete (step S12).

[0065] Next, select another group of energy storage elements and follow the same procedure as above (by switching the switch SW on and off) to fully charge this group of energy storage elements.

[0066] The above procedure is repeated, and if a storage module is specified, the specified module is charged. If no module is specified, it is determined whether the charging of all storage elements is complete. If the charging of the storage elements to be charged is not yet complete, the next group of storage elements to be charged is selected and specified, and the process returns to step S11 to continue charging the uncharged storage elements. On the other hand, if the charging of all storage elements to be charged is complete, the charging operation of the first supplemental charging method of the storage unit is terminated (step S13). The display and other elements are optional.

[0067] The first supplemental charging method for this energy storage unit is implemented based on the same principles as the basic charging method for the energy storage unit described above. Specifically, the change in terminal voltage is a function of the voltage of the parallel-connected energy storage element group and the amount of charge each energy storage element group possesses. When the energy storage element is a capacitor, the relationship Q = C·V holds between the amount of charge Q, the increased terminal voltage V, and the capacity C of the parallel-connected energy storage element group. Therefore, the capacity and the amount of charge or energy that can be charged for each parallel-connected energy storage element group can be easily calculated. The maximum and minimum capacities of the energy storage element groups can also be calculated. As a result, it is natural that the allowable charge amount for each energy storage element group can be calculated individually.

[0068] Next, we will explain a second supplemental charging method for the energy storage unit, which is a supplemental charging method different from the first supplemental charging method. Figure 4 is a flowchart of the second supplemental charging method for the energy storage unit, which, following Figures 2 and 3, individually charges a specific group of energy storage elements or all of the energy storage elements that make up the energy storage unit. In this explanation based on the flowchart, as with the explanations based on Figures 2 and 3 above, we will assume that the energy storage unit is configured using capacitors as the energy storage elements and a group of capacitors as the group of energy storage elements, as shown in Figure 1.

[0069] This charging routine assumes that charging has been completed according to the basic charging routine, that is, after the energy storage unit described above has been charged according to steps S1 to S7, or that charging is performed using this charging routine alone. First, the charging unit control unit 260 checks the instructions from the energy storage mode selection unit 270. If there is an instruction to measure the terminal voltage of the energy storage element group, the voltage measurement switch group SWD(x) (x is an integer from 1 to n) is operated to measure the terminal voltage of all energy storage element groups constituting the energy storage module and record them along with the energy storage element group number in descending order of terminal voltage. If there is no instruction, this step is terminated without taking any action (step S20).

[0070] Next, the group of energy storage elements to be charged is selected. Whether to charge a specific group of energy storage elements or the entire group of energy storage elements, and whether to charge them in order of lowest terminal voltage (i.e., lowest amount of stored energy) or in order of energy storage element number, etc., is determined by the information received from the charging mode selection unit 270 via the charging unit control unit 260, and the group of energy storage elements to be charged first is determined (step S21).

[0071] First, the switches necessary for charging the designated group of energy storage elements and measuring the terminal voltage are closed, and then the charging operation is started. The charging operation and terminal voltage measurement are continued, and when the group of energy storage elements is fully charged, the contacts of all switches related to the charging of the group of energy storage elements are opened, and the fact that the charging of the group of energy storage elements is complete is recorded, and the charging operation is terminated (step S22).

[0072] First, the system checks whether the charging of all designated energy storage elements has been completed using the charging completion information for the energy storage elements. If the charging of the target energy storage elements has not yet been completed, the system specifies the next target energy storage elements according to conditions such as the instruction information from the energy storage mode selection unit 270, the charging completion information for the energy storage elements, the charging necessity information for the energy storage elements, and the terminal voltage information for the energy storage elements, and then returns to the beginning of step S22. If it is determined that the charging of all target energy storage elements constituting the energy storage unit has been completed, the system completes all of the second supplementary charging operations (step S23).

[0073] Furthermore, it should be noted that the handling of energy storage elements other than the designated group that have not yet been fully charged will be in accordance with the operating principles of the device.

[0074] By following the routine described above, the basic charge of the energy storage unit can be performed, and then supplemental charge 1 or supplemental charge 2 can be selectively performed depending on the conditions and environment required for the supplemental charge. This makes it possible to solve all of the various problems described in the section on problems to be solved by the present invention at once.

[0075] As mentioned above, the energy storage unit uses a capacitor as an energy storage element and a group of capacitors as an energy storage element, as explained in the text and drawings. More specifically, it can be said that so-called electric double-layer capacitors, which are all capable of discharge, are most suitable for application to this invention. By applying electric double-layer capacitors as capacitors to this invention, it is possible to configure an energy storage unit with capacitors ranging from several thousand F (farads) to tens of thousands of F (farads).

[0076] Furthermore, the characteristics of energy storage units that use capacitors as energy storage elements include, in addition to the large energy storage capacity mentioned above, the ability to rapidly charge in an extremely short time, virtually no performance degradation even after repeated charge and discharge cycles, resulting in a cycle life of several million cycles, high power density, no limitations on the depth of discharge (i.e., complete discharge is possible), and a wide operating temperature range, among many other features.

[0077] Therefore, it excels in its role as an emergency power source (backup power source) in situations where the power supply momentarily fails, such as a so-called momentary power outage under relatively heavy load conditions in a poor surrounding environment.

[0078] However, the present invention can also be applied to energy storage units that utilize lithium-ion secondary batteries as energy storage elements, where it is functionally necessary to retain a certain amount of charge during use. This is because, apart from the need to retain a certain amount of charge, they basically have the same properties as capacitors.

[0079] Furthermore, the energy storage element used in the charging method for the energy storage element according to the present invention is not limited to capacitors. That is, although the charging method for an energy storage unit consisting of a capacitor secondary battery according to the present invention constitutes an energy storage unit by connecting multiple groups of capacitors, each consisting of capacitors connected in parallel, in series with each other, the energy storage element is not particularly limited to capacitors and can be applied to other energy storage elements, such as lithium-ion secondary batteries, lead-acid batteries, nickel-metal hydride secondary batteries, and other chemical secondary batteries.

[0080] Here, if the energy storage elements are chemical secondary batteries such as lithium-ion secondary batteries, lead-acid batteries, or nickel-metal hydride secondary batteries, it is necessary to understand the various charge and discharge characteristics of the constituent batteries in advance (see the voltage-charge characteristic diagram in Figure 5(b)). Then, by calculating the change in voltage from the individual voltage values ​​of each group of energy storage elements connected in parallel before and after the charge Q is applied, the current allowable charge amount for each group of energy storage elements is calculated, and the allowable charge amount for the energy storage unit is determined. Charging is then performed by sending this charge amount to the energy storage unit connected in series.

[0081] If the energy storage element is, for example, a lithium-ion battery, then if any one of the energy storage elements or groups of energy storage elements is completely discharged or discharged above a specified lower limit voltage, it will no longer be usable as an energy storage unit. Therefore, by combining the basic charging method according to the present invention with the first supplementary charging method or the second supplementary charging method, the present invention ensures that any of the energy storage elements or groups of energy storage elements constituting the energy storage unit are not completely discharged or discharged above a specified lower limit voltage, thereby providing the advantage of being able to use the energy storage unit for a long period of time. In other words, as described above, even if the energy storage element is a chemical secondary battery, the effects of the present invention can be sufficiently demonstrated if it is used in a way that does not adversely affect it. Therefore, even if each energy storage element constituting the group of energy storage elements in the present invention is replaced with a chemical secondary battery, the effects of the present invention can still be sufficiently demonstrated, and we would like to emphasize that the scope of the rights of the present invention is also included when each energy storage element is replaced with a chemical secondary battery.

[0082] It should be noted that the circuit block diagrams, flowcharts, and other explanatory drawings shown in each of the embodiments described above are merely examples, and it goes without saying that the structure, materials, circuit configuration, etc., can be appropriately modified within the scope that allows the effects of the present invention to be realized.

[0083] For example, the energy storage unit according to the present invention generally includes all units composed of a group of energy storage elements formed by connecting multiple energy storage elements in series, parallel, or series-parallel, and further connecting these combinations in series, parallel, or series-parallel as needed, and the energy storage unit includes all units composed by further connecting each group of energy storage elements in series, parallel, or series-parallel as needed.

[0084] The following explains the major differences between energy storage devices that use capacitors as the energy storage element, where the energy storage unit itself is a capacitor, and energy storage devices that use large-capacity secondary batteries, where the energy storage element is a chemical secondary battery such as a lithium-ion battery. First, we will explain the advantages of energy storage devices using capacitors compared to energy storage devices using chemical secondary batteries.

[0085] Since a capacitor stores electric charge between its electrodes in principle, it has the following advantages (1) to (4) compared to energy storage elements using chemical secondary batteries. (1) In the case of an energy storage device using a capacitor, since the charge only moves between electrodes, the internal resistance is small and the delay in operation is inevitably much less compared to an energy storage device using a chemical secondary battery. (2) In the case of an energy storage device using a capacitor, since the current is simply fed into the device, the allowable current value when flowing out is much larger compared to an energy storage device using a chemical secondary battery, because it only involves the exchange of charge between electrodes. Here, the main constraint is the resistance value of the current path of the capacitor, and this value is largely determined by the physical structure of the product. (3) In the case of an energy storage device using a capacitor, because the charge is stored between the electrodes, the limitations on the number of charge / discharge cycles and operating life are significantly fewer compared to an energy storage device using a chemical secondary battery. (4) In the case of an energy storage device using a capacitor, the operating temperature range is overwhelmingly wider than that of an energy storage device using a chemical secondary battery, as it operates as long as the movement of charge between electrodes is not hindered.

[0086] On the other hand, in the case of energy storage devices using capacitors, the energy density is still lower than that of chemical secondary batteries such as lithium-ion batteries. This is because chemical secondary batteries generate electricity through chemical reactions. As a result, secondary batteries have high resistance between electrodes and high internal resistance. Furthermore, because they generate charge through chemical reactions, there is a delay in operation. In addition, secondary batteries are subject to current limitations in order to keep the reaction rate of the chemical reaction within an appropriate range when supplying / discharging current.

[0087] Specifically, because it utilizes chemical reactions within the electrodes, it requires ion movement time and reaction time, and the resistance due to the chemical reaction is also large, which creates a fundamental difference from capacitor-based energy storage devices in that it limits the current that can be passed. In addition, it is greatly constrained by the heat generated by the current. In other words, if the temperature rises too high, the chemical reaction proceeds too quickly, leading to increased heat generation, creating a vicious cycle. Therefore, it is necessary to strictly control the heat generation within an acceptable range to avoid this situation. Furthermore, the current values ​​when injecting / discharging current in a chemical secondary battery are orders of magnitude smaller than those in a capacitor secondary battery. On the other hand, in the case of a capacitor secondary battery, since the current is simply physically added and removed, the current values ​​when injecting / discharging current are much larger than those in a chemical secondary battery.

[0088] As explained above, because chemical secondary batteries utilize chemical reactions, the simultaneous generation of unwanted reaction products during these reactions inevitably limits the number of charge / discharge cycles and operating life. Furthermore, as mentioned above, the operating temperature range of chemical secondary batteries is limited to the temperature range within which the chemical reaction is permissible. Consequently, it is naturally inappropriate to use chemical secondary batteries in low-temperature or high-temperature operating environments. However, lithium-ion batteries have a higher energy density than capacitors.

[0089] Therefore, in large-scale energy storage systems, the following essential differences arise between energy storage devices using capacitors and energy storage devices using large-capacity secondary batteries such as lithium-ion batteries. (a) Although the energy density of a capacitor is moderate, its power density is much higher than that of a chemical secondary battery because its maximum current is very large. (b) In order to handle high power in a chemical secondary battery, a corresponding amount of stored energy is required. (c) In the case of a capacitor, there is no relationship between the amount of stored energy and the amount of electrical energy, so there is no constraint in this respect. (d) In a power storage device with a storage capacity of 1 kW / h (1 hour), a lithium-ion battery can handle power up to 1 kW / h in any way, but it cannot handle anything above that, even if the power source is able to do so. On the other hand, in the case of a capacitor, even with a 1 kW / h power storage device, the power can be increased up to the capacitor's maximum allowable current value for a short period of time, depending on the power source's response.

[0090] In other words, a power storage device consisting of a 1kW / h (1 hour) capacitor can handle 2kW / 30 minutes, 4kW / 15 minutes, and 12kW / 5 minutes. If the power supply is sufficient, it is theoretically possible to dramatically shorten the charging time of a power storage device using a capacitor compared to one using a secondary battery such as a lithium-ion battery, and in reality, a correspondingly significant reduction in charging time is naturally possible.

[0091] Finally, in order to facilitate understanding of the advantages of the present invention, we will introduce some specific examples. For example, in cases where the load is large and the power supplied to the load occasionally experiences momentary power outages (interruptions), the first supplementary charging method is performed after the basic charging method to fully charge all the energy storage elements individually.

[0092] In other words, if the energy storage element is, for example, an electric double-layer capacitor, and a momentary power outage occurs, supplying a considerable amount of power to the load as emergency power from the energy storage unit, then by performing the first supplementary charging method following the basic charging method described above, all the energy storage elements can be fully charged and reused as a backup power source any number of times (unlike chemical secondary batteries, which are limited by the number of uses).

[0093] Separately, if a momentary power outage occurs, but the timing of the next one is far off, and the energy storage unit has consumed a considerable amount of charge stored as emergency power, it is reasonable to assume that there will not be an immediate need to supply further emergency power. In such a case, it is advisable to fully charge all the energy storage elements of the energy storage unit using the first supplementary charging method with a certain amount of buffer time in preparation for the next power outage.

[0094] Furthermore, in cases where the load is not as large as described above, but power outages occur frequently, when charging the energy storage unit, either first charge the unit to the minimum necessary level using the basic charging method, or, in addition to this, fully charge all the energy storage elements using the first supplementary charging method and prepare this energy storage unit as a backup power source.

[0095] Furthermore, if a power outage occurs after the energy storage unit has been installed as a backup power source, it will temporarily supply the necessary and sufficient amount of power to the load in order to quickly return to a state where it can function as the next backup power source.

[0096] Then, after the energy storage unit has been configured to function as a backup power source, in preparation for the next momentary power outage that may occur again in a short period of time, the energy storage unit is charged using a second charging method, starting with the group of energy storage elements with the least amount of charge, and rapidly charging the required number of elements in sequence as time permits.

[0097] In this way, a second supplemental charging method is implemented to quickly and adequately charge the energy storage unit, enabling it to function as a backup power source again in preparation for the next momentary power outage, which may occur at any time. This ensures that even if such power outages occur frequently after the initial outage, the system can adequately respond and supply the necessary power to the load during the outage.

[0098] Furthermore, by charging the capacitor-based energy storage unit in a short time using the basic charging method, the present invention allows for easy and quick repeated charging multiple times a day in daily life, such as when running various errands in an area not far from home using an electric vehicle, electric assist bicycle, electric motorcycle, or electric moped, making it extremely convenient. In addition, the basic charging of the energy storage unit according to the present invention enables rapid charging and can supply a large current sufficient to handle the large torque required when starting a mobility device.

[0099] Furthermore, even if the energy storage unit has not been used for a certain period of time, the first or second supplemental charging method can be used to fully charge all of the energy storage elements of the energy storage unit, and then supply a large current that is sufficient to rapidly charge a means of transportation such as the electric vehicle mentioned above, and that can adequately handle the large torque required when starting the mobility device.

[0100] The reason for appropriately selecting either the first or second supplemental charging method based on the usage pattern of the energy storage unit is that, as mentioned above, even if a sufficient basic charge is performed, if the energy storage unit is not used for a long period of time, the amount of charge inside the unit will gradually decrease due to natural discharge, etc. This method was conceived as a countermeasure against this.

[0101] For example, if a situation arises where it is necessary to move quickly using mobility within a short distance, the individual energy storage elements are charged using a second supplemental charging method for this emergency, short-distance mobility.

[0102] In this process, as described above, the group of energy storage elements with the smallest amount of charge stored at that time is first fully charged, and then the group of energy storage elements with the next smallest amount of charge is individually charged. This individual charging of each group of energy storage elements is carried out according to the procedure of the second supplementary charging method, and the minimum number of energy storage elements necessary for the time being are charged from the group of energy storage elements that make up the energy storage unit.

[0103] Specifically, a second individual charge is performed by determining, using a control means (not shown here), the amount of charge appropriate to the power to be supplied from the group of energy storage elements for each of the multiple energy storage elements capable of storing energy.

[0104] On the other hand, if there is some time to spare before the energy storage unit is used again to supply power from it, and if, in addition to this, the mobility powered by the energy storage unit must travel long distances, then it is best to fully charge all the energy storage elements using the first supplemental charging method.

[0105] This makes it possible to fully charge the energy storage unit itself by first charging the charging unit using the basic charging method, and then completely replenishing the amount of charge lost due to self-discharge and leakage current.

[0106] Furthermore, if the time until the energy storage unit is actually used afterward is unpredictable, a second supplemental charge is performed to fully charge as many energy storage elements as possible, starting with the group with the least amount of charge and progressing through groups with the least amount of charge.

[0107] This allows the energy storage unit to be charged with an appropriate amount of charge depending on the time remaining until it is actually used. In other words, if there is not enough time, the minimum number of energy storage elements will be fully charged, and if there is ample time, all energy storage elements will be fully charged to improve usability.

[0108] The above is an example of a charging method for the energy storage unit consisting of a capacitor secondary battery of this embodiment. However, in addition to this, for example, when the engine, which is the main power source of construction machinery used in harsh environments, makes an emergency stop for some reason, the energy storage unit can be effectively utilized by using the above-described basic charging method, the first supplementary charging method, and the second supplementary charging method individually or in appropriate combinations, depending on the magnitude of the load required to drive the safety actuator and the frequency of engine troubles.

[0109] Furthermore, in the case of supplying electricity to power generation facilities that utilize natural energy sources such as wind power and solar power, the amount of electricity generated by power generation facilities that utilize natural phenomena depends on the natural environment, and therefore inevitably fluctuates considerably based on the weather conditions at the time. In other words, there is an inherent problem in that power generation facilities using natural energy sources cannot always generate electricity stably with a constant inertia.

[0110] Due to these unique circumstances, if the amount of electricity generated by renewable energy power generation facilities is large, the amount of electricity generated will significantly exceed the amount of electricity that needs to be supplied at that time. Therefore, the surplus is stored in a capacitor energy storage device.

[0111] Furthermore, if the amount of electricity generated decreases due to the operating status of power generation facilities that also use renewable energy, it will fall considerably below the amount of electricity that needs to be supplied at that time. By supplying the deficit from the capacitor storage device that has been charged as described above, it becomes possible to supply a stable amount of electricity, similar to hydroelectric or thermal power generation.

[0112] In such cases, by implementing the charging method for a power storage unit consisting of a capacitor secondary battery according to the present invention, the most preferable charging method based on the individual type of power generation equipment utilizing natural energy under various natural conditions, namely the basic charging method, the first supplementary charging method, and the second supplementary charging method according to the present invention, can be implemented by combining a capacitor storage battery and the charging method for a power storage unit consisting of a capacitor secondary battery according to the present invention, taking into account the individual generation conditions of power generation based on weather conditions and the type of power generation equipment, thereby realizing a stable power supply tailored to each power generation equipment.

[0113] However, as stated above, even if each energy storage element constituting the energy storage element group in this invention uses a chemical secondary battery instead of a capacitor, the present invention can still exert sufficient effects. Therefore, we would like to emphasize that even when each energy storage element is replaced with a chemical secondary battery, the scope of the present invention remains within reach. [Explanation of Symbols]

[0114] 100 Energy Storage Units 200 Energy Storage Unit Control Unit 210 All-in-one charging power unit 220 Individual charging power supply section 250 Voltage detection unit 260 Switch switching control unit 270 Charging mode selection section Switches SWU-1, SWU-2 Switch SWC(1-1), SWC(1-2) Switch SWC(2-1), SWC(2-2) Switch SWC(3-1), SWC(3-2) Switches SWC(n-1), SWC(n-2) Switch SWD-1, SWD-2 Switch SWD(1-1), SWD(1-2) Switch SWD(2-1), SWD(2-2) Switch SWD(3-1), SWD(3-2) Switch SWD(n-1), SWD(n-2) Capacitors C1-1, C1-2, C1-3, C1-(a-1), C1-a Capacitors C2-1, C2-2, C2-3, C2-(b-1), C2-b Capacitors C3-1, C3-2, C3-3, C3-(c-1), C3-c Capacitors Cn-1, Cn-2, Cn-3, Cn-(x-1), Cn-x

Claims

1. A method for charging a capacitor secondary battery, which consists of a single energy storage element made of a capacitor, or a group of multiple energy storage elements, m sets (where m is a natural number), connected in parallel, in series, parallel, or series-parallel, Step S1 involves measuring the terminal voltages for each of the first to n (where n is a natural number of 2 or more) groups of energy storage elements that constitute the energy storage unit. Step S2 involves accumulating charge δQ for each group of energy storage elements by flowing a predetermined charge δQ through the first to nth groups of energy storage elements connected in series in order to identify the group of energy storage elements with the smallest energy storage capacity among the aforementioned groups of energy storage elements. Step S3 involves measuring the terminal voltage of each energy storage element group after the charge δQ has been applied to each energy storage element group in accordance with step S2. Step S4 involves calculating the change in the terminal voltage measured in step S3 at the time of charge capacity determination for each group of energy storage elements, and the change in the terminal voltage measured in step S1. In step S4, we attempt to identify the group of energy storage elements that has the largest change in terminal voltage among the calculated terminal voltages for each group of energy storage elements, that is, the group of energy storage elements with the lowest energy storage capacity. If, under these conditions, it is determined that the group of energy storage elements with the lowest energy storage capacity cannot be identified, and the number of repetitions of steps S2 to S5 is less than a predetermined number, step 5 involves storing the terminal voltage information of the group of energy storage elements, adding 1 to the number of repetitions, and then returning to step S2; if the number of repetitions exceeds a predetermined number, the charging operation according to this procedure is terminated. Step 6 involves estimating and calculating the amount of charge required for the group of energy storage elements with the lowest energy storage capacity to reach full charge, based on the aforementioned information identifying the group of energy storage elements with the lowest energy storage capacity. A method for charging a power storage unit consisting of a capacitor secondary battery, characterized by having step S7, which involves applying the amount of charge calculated in step S6 to the power storage unit, and then completing the charging operation of the power storage unit.

2. A charging method for a storage unit consisting of a capacitor secondary battery, wherein a first supplementary charge is performed after the basic charge described in Claim 1, characterized in that after the basic charge is completed, a group of storage elements that have not yet been fully charged is identified by measuring the voltage between their terminals, and each of the identified group of storage elements that require the first supplementary charge is fully charged, and the first supplementary charge is completed when all of the group of storage elements are fully charged.

3. A charging method for a capacitor secondary battery energy storage unit, wherein, after performing the basic charging described in Claim 1, a second supplementary charge is performed to fully charge the group of energy storage elements when the amount of charge of the group of energy storage elements decreases based on self-discharge or leakage current, characterized in that the second supplementary charge is performed by identifying the group of energy storage elements with the least amount of charge by measuring the voltage between each terminal of the group of energy storage elements and prioritizing individual charging of that group, or sequentially individual charging of the groups of energy storage elements whose remaining charge is low.

4. A method for charging an energy storage unit according to any one of claims 1 to 3, characterized in that each energy storage element constituting the group of energy storage elements is a chemical secondary battery instead of a capacitor.

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