Power supply control device and power storage system
The power supply control device manages the state of charge of a secondary power supply with higher output but lower capacity to extend its lifespan by adjusting input/output operations based on usage frequency, addressing the issue of shortened lifespan in existing power supply systems.
Patent Information
- Application Number
- JP2022075316
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-04-28
- Publication Date
- 2025-08-07
- Estimated Expiration
- 2042-04-28
AI Technical Summary
The distribution method in existing power supply systems, such as those described in Patent Document 1, leads to a shortened lifespan of power supplies, resulting in high replacement costs, which is not limited to vehicle-mounted systems but also applies to power storage systems connected to power grids.
A power supply control device that includes a determination unit to manage the state of charge (SOC) of a second power supply with a larger output but smaller capacity, adjusting input/output instructions based on the frequency of use to reduce the frequency of charge and discharge, thereby reducing temperature rises and extending the lifespan of the power supply.
The solution effectively extends the life of the power supply by controlling input/output operations based on the frequency of use, reducing charge/discharge amounts and temperature increases, thus enhancing the durability of the power supply.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a power supply control device and a power storage system. [Background technology]
[0002] In the power supply system described in Patent Document 1, due to the demand for high capacity and high output, a high-capacity power supply and a high-output power supply are connected in parallel via a power conversion circuit, etc. This power supply system is installed in a vehicle, and the method of distributing power between the two types of power supplies is changed depending on the driving mode. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-187756 Summary of the Invention [Problem to be solved by the invention]
[0004] However, in the power supply system described in Patent Document 1, the distribution method shortens the lifespan of the power supply, which can lead to high power supply replacement costs. For this reason, there is a demand for extending the lifespan of the power supply. Note that this issue is not limited to power supply systems installed in vehicles, but also applies to power storage systems that input and output power to and from a power grid. [Means for solving the problem]
[0005] A power supply control device that solves the above problem is a power supply control device that controls a power storage system including a first power supply and a second power supply that has a smaller capacity but a larger output than the first power supply, and is equipped with a determination unit that determines an input / output instruction value for returning the SOC to a center SOC that serves as the control center when the second power supply performs input / output control, based on an SOC usage frequency, which is the frequency of the SOC that indicates the state of charge of the second power supply after repeated input and output of power, and the determination unit reduces the SOC as the SOC usage frequency increases.
[0006] According to the above configuration, the input / output instruction value is reduced as the SOC frequency of the second power source increases based on the frequency of use of the SOC. This allows the second power source to be controlled according to the frequency of use of the SOC, suppressing a temperature rise due to an increase in the current value of the second power source while reducing the amount of electricity charged and discharged (Ah / day). This allows the life of the power source to be extended.
[0007] In the power supply control device, it is preferable that the input / output command value of an SOC whose frequency of use of SOC is higher than a predetermined value is set to be smaller than the input / output command value of an SOC whose frequency of use of SOC is equal to or lower than the predetermined value.
[0008] According to the above configuration, by dividing the frequency of SOC use by a predetermined value, the input / output command value of the SOC when the frequency of SOC use is higher than the predetermined value can be particularly reduced, thereby further reducing the amount of electricity (Ah / day) charged / discharged and the current value of the second power source.
[0009] It is preferable that the power supply control device further comprises an acquisition unit that acquires the SOC usage frequency, and the determination unit determines an input / output instruction value for returning the SOC to the center SOC based on the SOC usage frequency acquired by the acquisition unit.
[0010] According to the above configuration, the input / output instruction value can be determined based on the actual usage frequency of the second power source acquired by the acquisition unit, and therefore can be adapted to the usage state of the second power source, and the charge / discharge electricity amount (Ah / day) can be further reduced while suppressing a temperature increase due to an increase in the current value of the second power source.
[0011] In the power supply control device, it is preferable that the determining unit increases the input / output command value as the SOC is used less frequently. According to the above configuration, the input / output command value is increased as the SOC is used less frequently, which reduces the fluctuation range of the SOC of the second power supply, thereby extending the life of the power supply.
[0012] In the above power supply control device, since the second power supply functions to back up the first power supply, it is preferable that when there is no output request, the second power supply inputs the SOC from the first power supply so that the SOC is returned to the central SOC and waits there.
[0013] According to the above configuration, the second power source receives power from the first power source to back up the first power source by providing high output when there is an output request. The input / output instruction value is determined based on the frequency of use of the SOC for inputting and outputting this power. At this time, the second power source is on standby at the center SOC, allowing the second power source to respond appropriately to the output request.
[0014] The power storage system that solves the above problem includes a first power source, a second power source that has a smaller capacity but a larger output than the first power source, and the power source control device. According to the above configuration, the input / output instruction value is reduced as the SOC frequency of the second power source increases based on the frequency of use of the SOC. This allows the power source to be controlled according to the frequency of use of the SOC, suppressing a temperature rise due to an increase in the current value of the second power source while reducing the amount of electricity charged and discharged (Ah / day). This allows the life of the power source to be extended. [Effects of the Invention]
[0015] According to the present invention, the life of the power supply can be extended. [Brief explanation of the drawings]
[0016] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a power storage system. [Figure 2] 3 is a diagram showing a calculation process of an output value performed by the power supply control device of the embodiment. [Figure 3] 4 is a flowchart showing an input / output instruction value update process of the power supply control device of the embodiment. [Figure 4] 6 is a graph showing the frequency of use of the SOC of the second power source of the power storage system according to the embodiment. [Figure 5]6 is a graph showing input and output values of a second power source of the power storage system of the embodiment. [Figure 6] 10 shows an upper and lower limit map and a reduction rate map of a second power source of the power storage system of the embodiment. [Figure 7] 6 is a graph showing the frequency of use of the SOC of the second power source of the power storage system according to the embodiment. [Figure 8] 6 is a graph showing input and output values of a second power source of the power storage system of the embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0017] An embodiment of a power supply control device and a power storage system will be described below with reference to Figures 1 to 8. In the power storage system, the power supply control device controls the output from and input to the power supply.
[0018] (Energy Storage System 10) As shown in FIG. 1, a power storage system 10 is connected to a commercial power grid 1 and inputs and outputs power to and from the commercial power grid 1. The power storage system 10 includes a capacity battery 11, an output battery 12, and a power supply control device 20. The capacity battery 11 corresponds to a first power source and has a larger capacity than the output battery 12. The capacity battery 11 is, for example, a lithium-ion secondary battery. The output battery 12 corresponds to a second power source and has a larger output than the capacity battery 11. The output battery 12 is, for example, a nickel-metal hydride secondary battery. The output battery 12 functions to back up the capacity battery 11 when output is required. For this reason, the power supply control device 20 waits, returning the SOC indicating the state of charge to a center SOC, in order to respond to sudden requests. When there is no output request, the power supply control device 20 inputs power from the capacity battery 11 to the output battery 12. For this reason, the output battery 12 inputs and outputs power so as to return its SOC to the center SOC. The central SOC is the SOC that serves as the control center when controlling input and output. The central SOC can be set arbitrarily.
[0019] A first measuring instrument 11A that measures the voltage, current, etc. of the capacitive battery 11 is provided on the connection line between the capacitive battery 11 and the commercial power grid 1. The first measuring instrument 11A outputs the measurement results to the power supply control device 20. A second measuring instrument 12A that measures the voltage, current, etc. of the output-type battery 12 is provided on the connection line between the output-type battery 12 and the commercial power grid 1. The second measuring instrument 12A outputs the measurement results to the power supply control device 20. The power supply control device 20 calculates the SOC of the capacitive battery 11 from the measurement results of the first measuring instrument 11A. The power supply control device 20 also calculates the SOC of the output-type battery 12 from the measurement results of the second measuring instrument 12A.
[0020] (Power supply control device 20) The Power Control Unit 20 may be configured as one or more processors that execute various processes according to a computer program (software). The processes executed by the Power Control Unit 20, i.e., the processor, include a power control method. The power control method includes an acquisition step and a determination step, which will be described later. The Power Control Unit 20 may also be configured as a circuit including one or more dedicated hardware circuits, such as an application-specific integrated circuit (ASIC), or a combination thereof, that execute at least some of the various processes. The processor includes a CPU and memory, such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute the processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer. The program stored on the computer-readable medium includes a power control program. The power control program causes the Power Control Unit 20 to execute the acquisition step and the determination step.
[0021] The power supply control device 20 includes an acquisition unit 21 and a determination unit 22. The acquisition unit 21 acquires the usage SOC frequency of the output-type battery 12. The usage SOC frequency is the frequency of the SOC of the output-type battery 12 after repeated input and output of power over a predetermined period. The predetermined period may be any period such as one month or one week. The determination unit 22 determines the input / output instruction value for returning the SOC of the output-type battery 12 to the center SOC based on the usage SOC frequency.
[0022] (Output value calculation process) Next, the calculation process of the output value of the power supply control device 20 will be described with reference to Fig. 2. When there is an output request from the commercial power grid 1, the power supply control device 20 calculates the output value according to the requested power.
[0023] First, the power supply control device 20 acquires the SOC of the output-type battery 12 and calculates the input / output instruction values of the output-type battery 12 (step S1). That is, the power supply control device 20 calculates the input / output instruction values of the output-type battery 12 so that the SOC of the output-type battery 12 returns to the center SOC.
[0024] Next, the power supply control device 20 calculates the power required by the capacity battery 11 (step S2). That is, the power required by the capacity battery 11 is calculated by subtracting the input / output instruction value of the output battery 12 calculated in step S1 from the output request of the commercial power grid 1.
[0025] Next, the power supply control device 20 calculates the power requirement of the output-type battery 12 (step S3). That is, the power requirement of the output-type battery 12 is calculated by subtracting the power requirement of the capacity-type battery 11 calculated in step S2 from the output requirement of the commercial power grid 1.
[0026] Next, the power supply control device 20 can obtain the output of the capacity type battery 11 calculated in step S1 and the output of the output type battery 12 calculated in step S2 as output values.
[0027] (Input / output indication value update processing) Next, the process of updating the input / output instruction values of the output-type battery 12 performed by the power supply control device 20 in step S1 of Fig. 2 will be described with reference to Fig. 3. Note that the power supply control device 20 performs input / output control using initially set input / output instruction values during initial operation. The power supply control device 20 also performs the process of updating the input / output instruction values of the output-type battery 12 at predetermined intervals.
[0028] 3, the power supply control device 20 first acquires a log of the SOC used by the output battery 12 during operation for a predetermined period (step S11). That is, the power supply control device 20 acquires the log of the SOC used by the output battery 12 in order to calculate the frequency of the SOC used by the output battery 12.
[0029] Next, the power supply control device 20 calculates the usage SOC frequency from the acquired usage SOC log (step S12). That is, as shown in FIG. 4, the acquisition unit 21 acquires the usage SOC frequency by calculating the number of times for each SOC in a predetermined period. In this embodiment, the central SOC is set to 60%, but other values may be used. Step S12 corresponds to the acquisition step.
[0030] Next, the power supply control device 20 calculates the input / output command values (step S13). That is, the determination unit 22 calculates the input / output command values when the SOC of the output-type battery 12 is returned to the center SOC based on the frequency of use of the SOC.
[0031] Next, the power supply control device 20 updates the calculated input / output instruction value (step S14). That is, the determination unit 22 rewrites the calculated input / output instruction value as a new input / output instruction value. The determination unit 22 determines the calculated input / output instruction value as the new input / output instruction value. Steps S13 and S14 correspond to the determination step.
[0032] (Calculation of input / output indication values) Next, calculation of the input / output instruction values of the output-type battery 12 by the power supply control device 20 in step S13 of Fig. 3 will be described with reference to Fig. 4 to Fig. 6. The center SOC of the output-type battery 12 is 60%.
[0033] As shown in Fig. 4, the frequency of SOC usage of the output-type battery 12 occurs between approximately 50% and 70%, with a peak SOC of 60%. The determining unit 22 reduces the input / output instruction value as the SOC usage frequency increases. In other words, the determining unit 22 increases the input / output instruction value as the SOC usage frequency decreases. The determining unit 22 may also reduce the input / output instruction value for an SOC whose SOC usage frequency is higher than a predetermined value compared to the input / output instruction value for an SOC whose SOC usage frequency is equal to or less than the predetermined value. In this case, the predetermined value is set to be at or near the inflection point of the SOC usage frequency.
[0034] The determination unit 22 determines the input / output command value by multiplying the preset upper and lower limit values by a reduction rate selected based on the frequency of use of the SOC (Equation (1)). Input / output indicated value = upper and lower limit values × reduction rate (1)
[0035] As shown by the dashed lines in Figure 5, upper and lower limits for the power-supply battery 12 are set in advance. The upper and lower limits for the power-supply battery 12 are indicated by straight lines that are zero when the SOC is 60%. The upper and lower limits can be set arbitrarily.
[0036] As shown in FIG. 6, the power supply control device 20 stores in advance an upper and lower limit map M1 and a reduction rate map M2. The upper and lower limit map M1 is a map that indicates upper and lower limit values for each SOC. The reduction rate map M2 is a map that indicates a reduction rate for the frequency of use of the SOC. The reduction rate decreases as the frequency increases. The reduction rate can be set arbitrarily. The determination unit 22 then selects a reduction rate for the frequency of use of the SOC for each SOC from the reduction rate map M2. The determination unit 22 then determines the input / output command value for each SOC by multiplying the upper and lower limit values in the upper and lower limit map M1 by the reduction rate.
[0037] Furthermore, the determination unit 22 may set the input / output command values for SOCs whose SOC usage frequency is higher than a predetermined value to zero. For example, when the SOC usage frequency is only near 60% as shown in Fig. 7, the determination unit 22 may set the input / output command values to zero for SOCs whose SOC usage frequency is not zero, in other words, for SOCs whose SOC usage frequency is certain, as shown in Fig. 8.
[0038] According to the above, at an SOC near the center SOC where the SOC is used frequently, the current value of the output-type battery 12 can be reduced by decreasing the input / output command value. Therefore, the amount of charge and discharge electricity (Ah / day) can be reduced while suppressing the temperature rise caused by the increase in current value. Furthermore, at an SOC far from the center SOC where the SOC is not used frequently or is low, the SOC can be quickly returned to the center SOC by increasing the input / output command value. Therefore, the fluctuation range of the SOC of the output-type battery 12 can be reduced.
[0039] Next, the effects of this embodiment will be described. (1) The input / output instruction value is reduced as the SOC frequency of the output-type battery 12 increases. This reduces the input / output control of the output-type battery 12 according to the SOC frequency, suppressing the temperature rise caused by the increase in the current value of the output-type battery 12 and reducing the charge / discharge electricity amount (Ah / day). This extends the life of the output-type battery 12.
[0040] (2) By dividing the SOC frequency of the power-type battery 12 by a predetermined value, the input / output command value of the SOC when the SOC frequency is higher than the predetermined value can be reduced. This allows the power-type battery 12 to further reduce its charge / discharge electricity amount (Ah / day) while suppressing temperature rise due to an increase in current.
[0041] (3) The input / output instruction value can be determined based on the actual usage SOC frequency of the output-type battery 12 acquired by the acquisition unit 21. Therefore, it can be adapted to the usage state of the output-type battery 12.
[0042] (4) The input / output instruction value is increased as the SOC is used less frequently. This reduces the fluctuation range of the SOC of the output-type battery 12. This extends the life of the output-type battery 12.
[0043] (5) The output-type battery 12 has a high output during use, and power is frequently input from the capacity-type battery 11 to back up the capacity-type battery 11. Therefore, the input / output instruction value can be determined based on the frequency of use of the SOC in this power input / output. This can extend the life of the output-type battery 12.
[0044] (Other embodiments) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.
[0045] In the above embodiment, the determiner 22 determines the input / output command values for the SOC when the SOC frequency is higher than the predetermined value to be smaller than the input / output command values for the SOC when the SOC frequency is equal to or lower than the predetermined value. However, the determiner 22 may determine the input / output command values according to the SOC frequency, regardless of the predetermined value.
[0046] In the above embodiment, the determiner 22 determines the input / output command values when returning the SOC to the center SOC based on the SOC usage frequency acquired by the acquirer 21. However, the determiner 22 may determine the input / output command values when returning the SOC to the center SOC based on a pre-created SOC usage frequency instead of the SOC usage frequency acquired by the acquirer 21.
[0047] In the above embodiment, the input / output command values are determined by multiplying predetermined upper and lower limit values by a reduction rate determined based on the frequency of use of the SOC. However, if the input / output command values for SOCs whose SOC frequency is higher than a predetermined value are determined smaller than the input / output command values for SOCs whose SOC frequency is equal to or lower than the predetermined value, and the input / output command values are determined larger for SOCs whose SOC frequency is lower, the upper and lower limit values may not be used.
[0048] In the above embodiment, the capacity battery 11, which is the first power source, is a lithium ion secondary battery, and the output battery 12, which is the second power source, is a nickel-metal hydride secondary battery. However, the first power source and the second power source may be combined in other ways as long as the second power source has a smaller capacity but a larger output than the first power source.
[0049] In the above embodiment, the power storage system 10 is connected to the commercial power grid 1. However, the power storage system 10 is not limited to being connected to the commercial power grid 1, and may be connected to other devices that require a power source. [Explanation of symbols]
[0050] 1…Commercial power grid 10...Energy storage system 11...Capacitive battery as the first power source 11A...First measuring instrument 12...Output battery as second power source 12A...Second measuring instrument 20...Power supply control device 21…Acquisition part 22...Decision Section
Claims
1. A power supply control device that controls a power storage system including a first power supply and a second power supply that has a smaller capacity but a larger output than the first power supply, a determination unit that determines an input / output instruction value for returning the SOC to a center SOC that serves as a control center when the second power source performs input / output control, based on a usage SOC frequency that is a frequency of an SOC that indicates a state of charge of the second power source after repeated input / output of electric power, The determination unit reduces the input / output command value as the frequency of use of the SOC increases. Power control device.
2. The determination unit sets the input / output command value of an SOC in which the frequency of use of the SOC is higher than a predetermined value to be smaller than the input / output command value of an SOC in which the frequency of use of the SOC is equal to or smaller than the predetermined value. The power supply control device according to claim 1 .
3. an acquisition unit that acquires the used SOC frequency, The determination unit determines an input / output command value for returning the SOC to the center SOC based on the frequency of use of the SOC acquired by the acquisition unit. The power supply control device according to claim 1 .
4. The determination unit increases the input / output command value as the SOC is used less frequently. The power supply control device according to claim 1 .
5. The second power supply functions to back up the first power supply, and when there is no output request, the second power supply inputs the SOC from the first power supply so as to return the SOC to the central SOC and waits while returning the SOC to the central SOC. The power supply control device according to claim 1 .
6. a first power source; a second power source having a smaller capacity but a larger output than the first power source; The power supply control device according to any one of claims 1 to 5 is provided. Energy storage system.
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