Power storage temperature system, power storage temperature system for energy storing system, and control method for temperature adjustment system

Abstract

A power storage temperature system (1A) comprises power storage units (2A)-(2C) and a temperature adjustment system (3) for adjusting the temperatures of the power storage units (2A)-(2C), and adjusts the temperature adjustment capability of the temperature adjustment system (3) in accordance with the states of charge of the battery storage units (2A)-(2C) or battery information from which the states of charge can be identified.

Description

Battery Temperature System, Battery Temperature System for Energy Storage System, and Control Method of Temperature Regulation System

[0001] The present invention relates to a technology for adjusting the temperature of a battery unit.

[0002] In recent years, the demand for energy storage systems (ESSs; also referred to as power storage stations) has been increasing. An ESS includes a battery bank in which a plurality of cells are connected in series. A large-capacity ESS is configured by connecting a plurality of battery banks (an example of a battery unit) in parallel.

[0003] An ESS is operated over a long period (e.g., 20 years). Along with the operation, the deterioration of the cells progresses, and it is known that the deterioration of the cells at high temperatures progresses particularly rapidly. Patent Document 1 discloses a technology for controlling the temperature of a battery unit.

[0004] Japanese Unexamined Patent Application Publication No. 2020-140955

[0005] In an energy storage system, energy saving is an issue. A battery unit may absorb heat or generate heat by a chemical reaction depending on the state of charge. By adjusting the temperature of the battery unit in consideration of the state of charge, reduction of power consumption can be expected compared to the case where the state of charge is not considered. Not only in an energy storage system, but also in a system having a battery unit, there is a similar issue. [[ID=I7]]

[0006] The battery temperature system includes a battery unit and a temperature regulation system that adjusts the temperature of the battery unit, and adjusts the temperature regulation ability of the temperature regulation system according to the state of charge of the battery unit or battery information that can specify the state of charge.

[0007] The present invention enables reduction of power consumption of the battery temperature system.

[0008] System configuration diagram plate of battery temperature unit, Plan view of battery unit, View of FIG. 2 from direction A, Diagram showing the relationship between SOC and heat absorption / generation during charging, Flowchart of cooling capacity adjustment process during charging, System configuration diagram of energy storage system, Block diagram of CMU, Block diagram of BMU, System configuration diagram of energy storage system, System configuration diagram of battery temperature unit

[0009] (Outline of this embodiment) An embodiment of the present invention of an energy storage temperature system will be described below. (1) The energy storage temperature system comprises an energy storage unit and a temperature control system for adjusting the temperature of the energy storage unit, and adjusts the temperature control capacity of the temperature control system according to the charge state of the energy storage unit or battery information that can identify the charge state. The temperature control capacity is a cooling capacity or a heating capacity.

[0010] According to the energy storage temperature system in (1), the temperature control capacity of the temperature control system is adjusted considering the charge state of the energy storage unit. Therefore, compared to cases where adjustment considering the charge state is not performed, a reduction in the power consumption of the energy storage temperature system can be expected. As a result, it can contribute to energy conservation.

[0011] (2) In the energy storage temperature system described in (1) above, the energy storage unit may have a first SOC range in which it undergoes an endothermic reaction by chemical reaction in a specific current direction. If the energy storage unit is in a specific current direction and is included in the first SOC range, the cooling capacity of the temperature control system may be stopped or reduced. According to (2), by refraining from cooling the energy storage unit during heat absorption, it is expected that the power consumption of the energy storage temperature system can be reduced.

[0012] (3) In the energy storage temperature system described in (1) or (2) above, the energy storage unit may have a second SOC range in which it undergoes an exothermic reaction by chemical reaction in a specific current direction. If the energy storage unit is in a specific current direction and is included in the second SOC range, the cooling capacity of the energy storage unit may be maintained or enhanced. According to (3), the temperature rise of the heat-generating energy storage unit can be suppressed.

[0013] (4) In the energy storage temperature system described in (1) above, the energy storage unit may have a first SOC range in which it undergoes an endothermic reaction by chemical reaction in a specific current direction. When the energy storage unit is in a specific current direction and is included in the first SOC range, the heating capacity of the temperature control system may be maintained or enhanced. According to (4), the temperature drop of the energy storage unit that absorbs heat can be suppressed.

[0014] (5) In the energy storage temperature system described in (1) or (4) above, the energy storage unit may have a second SOC range in which it generates heat through a chemical reaction in a specific current direction. If the energy storage unit is in a specific current direction and is included in the second SOC range, the heating capacity of the temperature control system may be stopped or reduced. According to (5), by refraining from heating the energy storage unit during heat generation, it is expected that the power consumption of the energy storage temperature system can be reduced.

[0015] This technology can be applied to control methods for energy storage temperature systems or temperature control systems for Energy Storage Systems (ESS). ESS require the installation of many energy storage units in a limited space (in other words, increased energy density). Energy storage temperature systems for ESS are generally expensive and operated over long periods. By applying this technology and adjusting the temperature control capacity of the temperature control system according to the charge state of the energy storage units or battery information that can identify the charge state, a high cost-effectiveness can be achieved.

[0016] <Embodiment 1> 1. System Configuration Diagram 1 of the Energy Storage Temperature System 1A is a system configuration diagram of the Energy Storage Temperature System 1A. The Energy Storage Temperature System 1A comprises a plurality of energy storage units 2A to 2C (collectively referred to as energy storage units 2) and a circulation system 3. The plurality of energy storage units 2A to 2C are collections of cells 12 connected in series or in series-parallel, and include energy storage packs and energy storage banks. The energy storage units 2A to 2C are equipped with sensors for acquiring the voltage V, current I, and temperature T of the energy storage units.

[0017] The circulation system 3 comprises a temperature control unit 4, circulation piping, a pump 8, and a control device 10. The circulation system 3 is an example of a temperature control system that adjusts the temperature of the energy storage units 2A to 2C.

[0018] The circulation piping consists of a supply pipe 5, multiple branch pipes 6A to 6C, and a return pipe 7. The multiple branch pipes 6A to 6C branch off from the supply pipe 5 at point X in Figure 1 and merge with the return pipe 7 at point Y in Figure 1. The circulating fluid circulates through the path of the temperature control unit 4, the supply pipe 5, the branch pipes 6A to 6C, and the return pipe 7.

[0019] Multiple branch pipes 6A to 6C correspond to multiple energy storage units 2A to 2C, and are connected to the multiple energy storage units 2A to 2C in a manner that allows for heat exchange. In this embodiment, as shown in Figures 2 and 3, the branch pipes 6 are built into the plate 14.

[0020] The plate 14 is a fixing member for the cell 12. The plate 14 is made of metal, and in this example, its top surface is the mounting surface for the cell 12. Each cell 12 of the energy storage unit 2 exchanges heat with the circulating fluid flowing through the branch pipe 6 via its bottom surface to regulate its temperature.

[0021] An insulating thermal conductive material (for example, a thermal interface material) may be interposed between the plate 14 and the cell 12. By interposing an insulating thermal conductive material, both insulation and thermal conductivity can be achieved between the plate 14 and the cell 12.

[0022] The temperature control unit 4 includes a tank for storing circulating fluid, a temperature control unit for adjusting the temperature of the circulating fluid, and a valve for adjusting the flow rate of the circulating fluid. The circulating fluid is a liquid that can adjust the temperature of the energy storage unit 2 by exchanging heat with it, and includes cooling water and hot water.

[0023] The temperature control unit 4 is typically a chiller, and may be a cooling unit that cools the energy storage unit 2 by circulating cooling water, or a heating unit that heats the energy storage unit 2 by circulating hot water. This embodiment describes an example in which a cooling unit is used for the temperature control unit 4.

[0024] The control device 10 includes a CPU 15 and a storage unit 16. The storage unit 16 stores a cooling capacity adjustment program that adjusts the cooling capacity of the circulation system 3 (see Figure 5).

[0025] The control device 10 is connected to each energy storage unit 2A to 2C via signal lines and acquires information on the voltage V, current I, and temperature T of each energy storage unit 2A to 2C. Based on the information on voltage V, current I, and temperature T, the control device 10 monitors the status of each energy storage unit 2A to 2C. The status of the energy storage unit 2 is, for example, SOH [%] or SOC [%]. SOH is an indicator of the degradation state of the energy storage unit 2, and SOC is an indicator of the charge state of the energy storage unit 2.

[0026] SOH can be calculated, for example, by actually measuring the battery capacity. It can also be calculated by methods that estimate capacity degradation based on temperature environment and elapsed time since manufacturing. SOC can be calculated, for example, by current integration or by the correlation between SOC and OCV.

[0027] SOH = Battery capacity / Initial battery capacity × 100 [%] SOC = Remaining capacity / Battery capacity × 100 [%]

[0028] 2. Adjusting the Cooling Capacity of the Circulation System Figure 4 shows the relationship between the State of Cooling (SOC) of the energy storage unit 2 and the heat absorption / exothermic reaction due to chemical changes during charging. During charging, the energy storage unit 2 undergoes an endothermic reaction due to chemical changes in SOC range A from SOC1 to SOC2 (endothermic region). Also, during charging, it undergoes an exothermic reaction due to chemical changes in SOC range B below SOC1 and SOC range C above SOC2 (exothermic region).

[0029] During discharge, the heat absorption and heat absorption characteristics are reversed, and the energy storage unit 2 undergoes an exothermic reaction in SOC range A and an endothermic reaction in SOC ranges B and C.

[0030] Thus, the energy storage unit 2 has a first SOC range that undergoes an endothermic reaction (SOC range A during charging, SOC ranges B and C during discharging) and a second SOC range that undergoes an exothermic reaction (SOC ranges B and C during charging, SOC range A during discharging) in a specific current direction (charging or discharging). Patent No. 6544489 discloses technology related to the chemical changes in the energy storage unit 2 that cause endothermic and exothermic reactions.

[0031] Figure 5 is a flowchart of the cooling capacity adjustment process of the circulation system 3 during charging. The cooling capacity adjustment process consists of five steps, S10 to S50. Note that the multiple energy storage units 2 are connected in parallel, and since their voltages match, the State of Charge (SOC) of each energy storage unit 2 is approximately the same.

[0032] When the energy storage temperature system 1 is put into operation, the control device 10 starts the circulation system 3 and begins temperature control of the energy storage units 2A to 2C (S10, S20). Specifically, it circulates cooling water to cool each of the energy storage units 2A to 2C and controls the temperature of the energy storage units 2A to 2C to a target temperature (for example, 20°C).

[0033] In parallel with temperature control of energy storage units 2A to 2C, the control device 10 monitors the direction of the current and the SOC of the energy storage units 2A to 2C, and determines whether the SOC is within the SOC range A while the energy storage units 2A to 2C are charging (S30). In this example, the determination of whether the SOC is within the SOC range A is made on behalf of energy storage unit 2A.

[0034] During charging, if the state of charge (SOC) of the energy storage unit 2A falls within the SOC range A (S30: YES), the energy storage units 2A and 2B and 2C are absorbing heat through a chemical reaction, so the control device 10 stops or reduces the cooling capacity (an example of temperature control capacity) of the circulation system 3. Specifically, it stops the circulation of the cooling water or reduces the flow rate (S40). Note that the circulation of the cooling water can be stopped with a pump, and the flow rate can be adjusted with a valve.

[0035] During charging, if the state of charge (SOC) of the energy storage unit 2A falls within the SOC range B or SOC range C (S30: NO), energy storage units 2A and 2B and 2C generate heat due to chemical reactions, so the control device 10 maintains or enhances the cooling capacity (an example of temperature control capacity) of the circulation system 3 (S50). By maintaining or enhancing the cooling capacity, the temperature rise of the heat-generating energy storage unit 2 can be suppressed.

[0036] During the charging of the energy storage unit 2, steps S30 to S50 are repeated, and when charging stops, the cooling capacity adjustment process is terminated.

[0037] Furthermore, during the discharge of the energy storage unit 2, the absorption and heating processes are reversed, with heat being generated in SOC range A and heat being absorbed in SOC ranges B and C. Therefore, in the cooling capacity adjustment process shown in Figure 5, it is possible to adjust the cooling capacity in the same way as during charging by maintaining or promoting the cooling capacity in S40 and stopping or reducing the cooling capacity in S50.

[0038] 3. Explanation of Effects According to this configuration, the cooling capacity of the circulation system 3 is adjusted considering the SOC of the energy storage units 2A to 2C, so a reduction in the power consumption of the circulation system 3 can be expected compared to the case where adjustment considering the SOC is not performed. In particular, it is expected to reduce the power consumption of the energy storage units 2A to 2C in the first SOC range (SOC range A during charging, SOC ranges B and C during discharging) where endothermic reactions occur due to chemical changes.

[0039] <Application Example> An example of applying this technology to an energy storage system S1 will be described. The energy storage system S is connected to the power grid G ​​and is a system that adjusts the supply and demand of electricity.

[0040] As shown in Figure 6, the energy storage system S1 includes a PCS 30 and an energy storage device 40. PCS 30 is an abbreviation for Power Conditioning System. The PCS 30 is a device that charges and discharges the energy storage device 40 and is installed on the power line L, which is the main circuit.

[0041] The PCS 30 comprises a power conversion unit 31 and a power control unit 33. The power conversion unit 31 is a bidirectional inverter, a bidirectional converter capable of both forward conversion (AC to DC) and reverse conversion (DC to AC). The power control unit 33 controls the power conversion unit 31 and adjusts the supply and demand of power.

[0042] The energy storage system 40 is composed of multiple energy storage banks 50. In this example, it is composed of five energy storage banks 50A to 50E connected in parallel. Energy storage banks 50A to 50E are connected to the PCS 30 via a power line L.

[0043] The power storage banks 50A to 50E are an assembly of a plurality of cells 61 and correspond to the power storage unit 2. The plurality of power storage banks 50A to 50E may be housed in a single housing such as a container, or may be housed in separate housings such as battery boards.

[0044] A branch pipe is connected to each of the power storage banks 50A to 50E in a heat-exchangeable manner, and temperature adjustment can be performed individually for each power storage bank by adjusting the flow rate of the cooling water.

[0045] As shown in FIG. 6, the power storage banks 50A to 50E are composed of a current sensor 51, a BMU 55, and a plurality of power storage modules 60 connected in series.

[0046] The power storage module 60 is composed of a plurality of cells 61 connected in series and a CMU 65. The plurality of cells 61 are fixed to a frame or a base and unitized. The cell 61 is a power storage element capable of charge and discharge, and various cells such as a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery can be applied.

[0047] As shown in FIG. 7A, the CMU (Cell Management Unit) 65 includes a CPU 66 and a storage unit 67, and monitors the temperature of the power storage module 60 and the cell voltage of each cell 61.

[0048] The BMU (Battery Management Unit) 55 is installed for each of the power storage banks 50A to 50E. As shown in FIG. 7B, the BMU 55 includes a CPU 56 and a storage unit 57, and monitors the state of each of the power storage banks 50A to 50E.

[0049] Specifically, the current of the power storage banks 50A to 50E is monitored based on the measurement result of the current sensor 51. Also, it is connected to each CMU 65 via a communication line, and information on the temperature of the power storage module 60 and the voltage of each cell 61 is acquired from the CMU 65. <000​​​​Multiple energy storage banks 50A to 50E are connected in parallel and have matching voltages, so their State of Charge (SOC) values ​​are nearly identical.

[0052] The circulation system 3 controls multiple energy storage banks 50A to 50E to a target temperature by circulating cooling water, while adjusting the cooling capacity according to the direction of the current and the state of temperature (SOC). For example, the system determines the direction of the current and the SOC based on energy storage bank 50A, and if the SOC falls within SOC range A during charging, it stops or reduces the cooling capacity. If the SOC falls within SOC range B or SOC range C during charging, it maintains or enhances the cooling capacity.

[0053] By adjusting the cooling capacity according to the direction of the current and SOC of the energy storage banks 50A to 50H, the power consumption of the circulation system 3 can be reduced, contributing to energy saving of the energy storage system S.

[0054] <Embodiment 2> Figure 8 is a block diagram of the energy storage system S2. The energy storage system S2 differs from the energy storage system S1 disclosed in Embodiment 1 in that a DC / DC converter 70 is provided for each energy storage bank 50A to 50E.

[0055] The DC / DC converter 70 performs the function of adjusting the voltage so that the voltages of the energy storage banks 50A to 50E match.

[0056] When a DC / DC converter 70 is provided, there is no crosscurrent (current) between banks due to voltage differences. Therefore, as shown in Figure 8, the State of Charge (SOC) may differ, and it is preferable to control the cooling capacity for each energy storage bank 50A to 50E.

[0057] Figure 9 is a system configuration diagram of the energy storage temperature system 1B. The difference between the energy storage temperature system 1B and the energy storage temperature system 1A of Embodiment 1 is that the branch pipes 6A to 6C are equipped with flow adjusters 9A to 9C.

[0058] Flow adjusters 9A to 9C adjust the flow rate of cooling water flowing through branch pipes 6A to 6C. Flow adjusters 9A to 9C may be electric valves that adjust the flow rate of cooling water by adjusting the opening degree of the valve, or solenoid valves that adjust the flow rate of cooling water by adjusting the duty cycle of valve opening and closing.

[0059] By providing flow adjusters 9A to 9C in each branch pipe 6A to 6C, the circulation and flow rate of the cooling water flowing through each branch pipe 6A to 6C can be adjusted. Therefore, the cooling capacity of the circulation system 3 can be individually adjusted according to the SOC of each energy storage bank 50A to 50H.

[0060] <Other Embodiments> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments are also included in the technical scope of the present invention.

[0061] (1) In the above embodiment, the energy storage temperature systems 1A and 1B were applied to the energy storage systems S1 and S2, but any system equipped with an energy storage unit 2 may be applied to other uses. For example, it may be applied to an in-vehicle power supply system such as an HEV or EV.

[0062] (2) In the above embodiment, as an example of the temperature control system 3, a circulation system 3 that uses a circulating fluid to adjust the temperature of the energy storage unit 2 was shown. The temperature control system 3 may be any other system that is capable of adjusting the temperature of the energy storage unit 2. For example, a system using a cooling element or a heating element may also be used.

[0063] (3) In the above embodiment, the energy storage unit 2 was cooled by circulating cooling water through the branch pipes 6A to 6C, but the energy storage unit 2 may also be heated by circulating hot water through the branch pipes 6A to 6C. When the energy storage unit 2 is heated by circulating hot water during charging, the heating capacity of the circulation unit 3 may be maintained or promoted in the first SOC range (specifically SOC range A) in which the energy storage unit 2 absorbs heat due to a chemical reaction, and the heating capacity of the circulation unit 3 may be stopped or reduced in the second SOC range (specifically SOC range B or SOC range C) in which the energy storage unit 2 generates heat due to a chemical reaction. When the energy storage unit 2 is heated by circulating hot water during discharge, the heating capacity of the circulation unit 3 may be maintained or promoted in the first SOC range (specifically SOC range B or SOC range C) in which the energy storage unit 2 absorbs heat due to a chemical reaction. Furthermore, the heating capacity of the circulation unit 3 may be stopped or reduced in the second SOC range (specifically SOC range A) in which the energy storage unit 2 generates heat due to a chemical reaction. The heating capacity is an example of the temperature control capacity of the present invention.

[0064] (4) In the above embodiment, the cooling capacity of the cooling unit was adjusted by focusing on the relationship between the heat absorption and heat generation due to the chemical change of the energy storage unit 2 and the SOC. Instead of SOC, battery information that can identify the SOC (for example, voltage information of the energy storage unit 2 such as OCV or CCV) may be used. In other words, the cooling capacity of the cooling unit may be adjusted by focusing on the relationship between the heat absorption and heat generation due to the chemical change of the energy storage unit 2 and battery information that can identify the SOC. The same applies when adjusting the heating capacity of the heating unit.

[0065] (5) In the above embodiment, the cooling capacity of the cooling unit was adjusted by focusing on the relationship between the heat absorption and heat generation due to the chemical change in the energy storage unit 2 and the state of charge (SOC). However, the heat absorption and heat generation do not necessarily have to be caused by a chemical change. Furthermore, the heat absorption and heat generation may be independent of the direction of the current. The same applies when adjusting the heating capacity of the heating unit.

[0066] 1A, 1B Energy storage temperature system 2A-2C Energy storage unit 3 Circulation system (temperature control system) 4 Temperature control unit 6A-6C Branch piping 10 Control device S1, S2

Claims

1. A storage temperature system comprising a storage unit and a temperature control system for adjusting the temperature of the storage unit, wherein the temperature control capability of the temperature control system is adjusted according to the charge state of the storage unit or battery information that can identify the charge state.

2. The energy storage temperature system according to claim 1, wherein the energy storage unit has a first SOC range in which it undergoes an endothermic reaction by chemical reaction in a specific current direction, and when the energy storage unit is in the specific current direction and is included in the first SOC range, the cooling capacity of the temperature control system is stopped or reduced.

3. An energy storage temperature system according to claim 1, wherein the energy storage unit has a second SOC range in which it undergoes an exothermic reaction by a chemical reaction in a specific current direction, and maintains or enhances the cooling capacity of the temperature control system when the energy storage unit is in a specific current direction and is included in the second SOC range.

4. An energy storage temperature system according to claim 1, wherein the energy storage unit has a first SOC range in which it undergoes an endothermic reaction by chemical reaction in a specific current direction, and maintains or enhances the heating capacity of the temperature control system when the energy storage unit is in the specific current direction and is included in the first SOC range.

5. The energy storage temperature system according to claim 1, wherein the energy storage unit has a second SOC range in which it undergoes an exothermic reaction by a chemical reaction in a specific current direction, and when the energy storage unit is in the specific current direction and is included in the second SOC range, the heating capacity of the temperature control system is stopped or reduced.

6. Energy storage temperature system for an energy storage system according to any one of claims 1 to 5.

7. A method for controlling a temperature control system, comprising adjusting the temperature control capability of the temperature control system according to the charge state of the energy storage unit or battery information that can identify the charge state.

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