Energy storage system, temperature control method, and computer program

Abstract

This invention provides an energy storage system, a temperature control method, and a computer program for adjusting the temperature of an energy storage element while minimizing the space required for airflow. [Solution] The energy storage system comprises an energy storage device including a plurality of energy storage elements connected to each other, a flow space provided in the energy storage device through which a fluid heat transfer medium that exchanges heat with the plurality of energy storage elements flows, and a flow path adjustment mechanism connected to the flow space that changes the direction in which the heat transfer medium flows through the flow space.

Description

Technical Field

[0001] The present disclosure relates to a power storage system, a temperature adjustment method, and a computer program.

Background Art

[0002] Power storage elements, which are secondary batteries capable of charging and discharging, are used in many fields such as electric vehicles and systems that store electric power generated by power plants. Generally, a power storage device including a plurality of power storage elements connected to each other in series or parallel is used. Power storage elements generate heat when charged and discharged. When the temperature of the power storage element becomes excessively high, deterioration of the power storage element is accelerated. Therefore, it has been practiced to cool the power storage elements by causing a cooling liquid for cooling the power storage elements to flow through the power storage device. Patent Document 1 discloses an example of a system for cooling power storage elements.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] If the power storage device is provided with a large number of flow pipes through which the cooling liquid flows in parallel, the power storage elements can be cooled effectively. However, as the number of flow pipes increases, the cost increases. Depending on the structure of the power storage device or the location where the power storage device is arranged, there may be insufficient space for arranging a plurality of flow pipes. Further, as the number of flow pipes increases, the number of connection portions increases, and the frequency of failures increases. For this reason, a technique for effectively cooling power storage elements is desired.

[0005] An object of the present disclosure is to provide a power storage system, a temperature adjustment method, and a computer program for effectively adjusting the temperature of a power storage element. [Means for solving the problem]

[0006] The energy storage system in this disclosure includes an energy storage device that includes a plurality of energy storage elements connected to each other, a flow space provided in the energy storage device through which a fluid heat transfer medium that exchanges heat with the plurality of energy storage elements flows, and a flow path adjustment mechanism connected to the flow space that changes the direction in which the heat transfer medium flows through the flow space. [Effects of the Invention]

[0007] According to the above embodiment, the temperatures of multiple energy storage elements included in the energy storage device are effectively regulated. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing an example configuration of an energy storage system. [Figure 2] This is a schematic diagram showing an example of the external appearance of an energy storage device. [Figure 3] This is a schematic diagram showing the flow path adjustment mechanism when the direction of flow of the heat transfer medium through the flow pipe is set to the positive direction. [Figure 4] This is a schematic diagram showing a flow path adjustment mechanism when the direction of flow of the heat transfer medium through the flow pipe is reversed. [Figure 5] This is a block diagram showing an example of the functional configuration of a control device. [Figure 6] This flowchart shows a first example of the procedure for temperature control processing performed by the control device. [Figure 7] This flowchart shows a second example of the procedure for temperature control processing performed by the control device. [Figure 8] This flowchart shows a third example of the procedure for temperature control processing performed by the control device. [Figure 9] This flowchart shows a fourth example of the procedure for temperature control processing performed by the control device. [Figure 10] This flowchart shows a fifth example of the procedure for temperature control processing performed by the control device. [Figure 11] This is a schematic cross-sectional view showing an energy storage device in which the space for current flow is hollow. [Modes for carrying out the invention]

[0009] (1) The energy storage system of the present disclosure comprises an energy storage device including a plurality of energy storage elements connected to each other, a flow space provided in the energy storage device through which a fluid heat transfer medium that exchanges heat with the plurality of energy storage elements flows, and a flow path adjustment mechanism connected to the flow space that changes the direction in which the heat transfer medium flows through the flow space.

[0010] In the energy storage system described in (1) above, the energy storage system comprises an energy storage device containing multiple energy storage elements, a flow space through which a heat transfer medium that exchanges heat with the multiple energy storage elements flows, and a flow path adjustment mechanism. The flow path adjustment mechanism changes the direction in which the heat transfer medium flows through the flow space. Near the point where the heat transfer medium flows out of the flow space, the temperature of the heat transfer medium is higher than near the point where the heat transfer medium flows into the flow space, making it difficult to cool the energy storage elements. By changing the direction in which the heat transfer medium flows, the temperature distribution of the heat transfer medium is changed, making it easier to cool energy storage elements that were previously difficult to cool, and thus multiple energy storage elements are effectively cooled. Similarly, multiple energy storage cells can also be effectively heated. In this way, the temperatures of multiple energy storage elements are effectively adjusted.

[0011] (2) The energy storage system described in (1) above further comprises a temperature control device that adjusts the temperature of the incoming heat transfer medium and discharges the heat transfer medium whose temperature has been adjusted, wherein the temperature control device is connected to the flow path adjustment mechanism, the heat transfer medium discharged from the flow space flows into the temperature control device through the flow path adjustment mechanism, and the heat transfer medium discharged from the temperature control device flows into the flow space through the flow path adjustment mechanism.

[0012] In the energy storage system described in (2) above, the energy storage system is equipped with a temperature control device. The heat transfer fluid that flows out from the flow space flows into the temperature control device through the flow path adjustment mechanism, where its temperature is adjusted. The temperature-adjusted heat transfer fluid flows out from the temperature control device and flows back into the flow space through the flow path adjustment mechanism. As the temperature-adjusted heat transfer fluid flows through the flow space, the temperature of the energy storage elements that exchange heat with the heat transfer fluid is adjusted.

[0013] (3) In the energy storage system described in (1) or (2) above, the flow space has a first flow port and a second flow port into which the heat medium flows in and out from the other, the flow path adjustment mechanism has an inlet into which the heat medium flows in, an outlet out which the heat medium flows out, a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve, the first three-way valve is connected to the first flow port, the second three-way valve and the fourth three-way valve, the second three-way valve is connected to the first three-way valve, the third three-way valve and the inlet, the third three-way valve is connected to the second flow port, the second three-way valve and the fourth three-way valve, and the fourth three-way valve is connected to the first three-way valve, the third three-way valve and the outlet, and the flow path adjustment The mechanism may change the direction in which the heat transfer medium flows by switching between a state in which the flow path between the inlet, the second three-way valve, the first three-way valve, and the first passage port is open, the flow path between the second passage port, the third three-way valve, the fourth three-way valve, and the outlet is open, the flow path between the first three-way valve and the fourth three-way valve is closed, and the flow path between the second three-way valve and the third three-way valve is closed, and a state in which the flow path between the inlet, the second three-way valve, the third three-way valve, and the second passage port is open, the flow path between the first passage port, the first three-way valve, the fourth three-way valve, and the outlet is open, the flow path between the first three-way valve and the second three-way valve is closed, and the flow path between the third three-way valve and the fourth three-way valve is closed.

[0014] In the power storage system of (3) above, the flow passage space has a first flow port and a second flow port, and the flow path adjustment mechanism has an inflow port and an outflow port through which the heat medium flows, and a first three-way valve, a second three-way valve, a third three-way valve, and a fourth three-way valve. When the flow path between the inflow port, the second three-way valve, the first three-way valve, and the first flow port is open, the flow path between the second flow port, the third three-way valve, the fourth three-way valve, and the outflow port is open, the flow path between the first three-way valve and the fourth three-way valve is closed, and the flow path between the second three-way valve and the third three-way valve is closed, the heat medium flows in one direction. When the flow path between the inflow port, the second three-way valve, the third three-way valve, and the second flow port is open, the flow path between the first flow port, the first three-way valve, the fourth three-way valve, and the outflow port is open, the flow path between the first three-way valve and the second three-way valve is closed, and the flow path between the third three-way valve and the fourth three-way valve is closed, the heat medium flows in the reverse direction. The flow path adjustment mechanism can change the flow direction of the heat medium by operating the plurality of three-way valves.

[0015] (4) In the power storage system according to any one of (1) to (3) above, the power storage system further comprises a control device that controls the flow path adjustment mechanism, wherein the control device acquires the temperature of the power storage element, and may cause the flow path adjustment mechanism to change the flow direction of the heat medium according to the acquired temperature.

[0016] The power storage system of (4) above comprises a control device that controls the flow path adjustment mechanism. The control device causes the flow path adjustment mechanism to change the flow direction of the heat medium in the flow passage space according to the temperature of the power storage element. Thereby, when the temperature of the power storage element is abnormal, the temperature distribution of the heat medium flowing through the flow passage space is changed, and the overall temperature is appropriately adjusted.

[0017] (5) In the power storage system according to (4) above, the flow passage space has two flow ports, wherein the heat medium flows in from one port and flows out from the other port, and when the difference between the temperature of the power storage element located at a position close to one of the two flow ports and the temperature of the power storage element located at a position close to the other flow port is equal to or greater than a predetermined value, the control device may cause the flow path adjustment mechanism to change the flow direction of the heat medium.

[0018] In the energy storage system described in (5) above, if the temperature difference between an energy storage element near one of the two flow ports in the flow space and an energy storage element near the other flow port exceeds a predetermined value, the direction in which the heat transfer medium flows through the flow space is changed. The temperature distribution of the heat transfer medium is changed, and the positions of energy storage elements that are easily cooled and those that are difficult to cool are swapped. As this process is repeated, the temperatures of multiple energy storage elements are adjusted overall, and the temperature difference between multiple energy storage elements becomes smaller.

[0019] (6) In the energy storage system described in (4) or (5) above, the flow space has two flow ports into which the heat transfer medium flows and out from which it flows, and the control device may cause the flow path adjustment mechanism to change the direction in which the heat transfer medium flows when the temperature of the energy storage element located near the flow port from which the heat transfer medium flows out of the two flow ports is above a predetermined upper limit temperature.

[0020] In the energy storage system described in (6) above, if the temperature of the energy storage element located closer to the outlet from which the heat transfer medium is flowing out of the two outlets in the flow space exceeds the upper limit temperature, the direction in which the heat transfer medium flows through the flow space is changed. The temperature distribution of the heat transfer medium is changed, and the positions of energy storage elements that are easily cooled and those that are difficult to cool are swapped. Energy storage elements that were difficult to cool and whose temperature was above the upper limit temperature become easier to cool, and the temperature of the energy storage elements decreases. As this process is repeated, it is suppressed that the temperature of the energy storage elements will not exceed the upper limit temperature by a large amount.

[0021] (7) In the energy storage system described in any one of (4) to (6) above, the flow space has two flow ports into which the heat transfer medium flows and out from which the heat transfer medium flows, and the control device may cause the flow path adjustment mechanism to change the direction in which the heat transfer medium flows when the temperature of the energy storage element located near the flow port into which the heat transfer medium flows exceeds a predetermined lower limit, and the temperature of the energy storage element located near the flow port out which the heat transfer medium flows is below the lower limit.

[0022] In the energy storage system described in (7) above, the direction in which the heat transfer fluid flows through the space is changed when the temperature of the energy storage element located near the outlet from which the heat transfer fluid flows exceeds the lower limit, and the temperature of the energy storage element located near the outlet from which the heat transfer fluid flows is below the lower limit. The direction in which the heat transfer fluid flows is changed when the energy storage elements near the outlet from which the heat transfer fluid flows are sufficiently heated, but the energy storage elements near the outlet from which the heat transfer fluid flows are not sufficiently heated. The energy storage elements that were not sufficiently heated are heated, and the temperature of the energy storage elements rises to a temperature at which charging and discharging is possible. By repeating this process, it becomes possible for multiple energy storage elements to perform charging and discharging as a whole. Alternatively, by changing the direction in which the heat transfer fluid flows, it is possible to perform charging and discharging of the energy storage elements when it is detected that the temperature of all energy storage elements has temporarily exceeded the lower limit. In this way, by utilizing the heat generated by the energy storage elements and causing the temperature of all energy storage elements to exceed the lower limit, continuous charging and discharging becomes possible.

[0023] (8) In the energy storage system described in any one of (4) to (7) above, the control device may calculate the current value that can be charged and discharged by the energy storage device based on the temperature of the energy storage element, and if the calculated current value is less than a predetermined value, the flow path adjustment mechanism may change the direction in which the heat transfer medium flows.

[0024] In the energy storage system described in (8) above, if the current value that can be charged and discharged by the energy storage device, which is calculated based on temperature, falls below a predetermined value, the direction in which the heat transfer medium flows through the passage space is changed. If the temperature of the energy storage elements is too low, the current that the energy storage elements can supply during charging and discharging decreases, and the current value that can be charged and discharged by the energy storage device decreases. As the process is repeated, the temperatures of the multiple energy storage elements contained in the energy storage device are adjusted to be nearly uniform, and the current value that can be charged and discharged by the energy storage device is kept high.

[0025] (9) In the energy storage system described in any one of (1) to (8) above, a control device is further provided, wherein the flow space has two flow ports into which the heat transfer medium flows and out from which the heat transfer medium flows, and the control device identifies a degree of deterioration representing the degree of deterioration of the energy storage element located closer to one of the two flow ports and a degree of deterioration of the energy storage element located closer to the other flow port, and if the difference between the degree of deterioration of the energy storage element located closer to the one flow port and the degree of deterioration of the energy storage element located closer to the other flow port is greater than or equal to a predetermined value, the flow path adjustment mechanism may be instructed to change the direction in which the heat transfer medium flows.

[0026] In the energy storage system described in (9) above, if the difference between the degree of degradation of an energy storage element located near one of the flow ports in the flow space and the degree of degradation of an energy storage element located near the other flow port exceeds a predetermined value, the direction in which the heat transfer medium flows through the flow space is changed. Energy storage elements that are difficult to cool will experience a temperature increase and degrade more rapidly. By changing the direction in which the heat transfer medium flows, the temperature distribution of the heat transfer medium is altered, swapping the positions of energy storage elements that are easily cooled and those that are difficult to cool. As a result, energy storage elements that were degrading become easier to cool, and the progression of degradation is suppressed.

[0027] (10) The temperature adjustment method of the present disclosure relates to an energy storage device including a plurality of energy storage elements connected to each other, and is a temperature adjustment method that adjusts the temperature of the energy storage elements using a flow space provided in the energy storage device through which a fluid heat transfer medium that exchanges heat with the plurality of energy storage elements flows, wherein the temperature of the energy storage elements is obtained, and the direction in which the heat transfer medium flows through the flow space is changed according to the obtained temperature.

[0028] The temperature adjustment method described in (10) above adjusts the temperature of the energy storage elements using a passage space through which a heat transfer medium that exchanges heat with multiple energy storage elements in the energy storage device flows. In this temperature adjustment method, the direction in which the heat transfer medium flows through the passage space is changed according to the temperature of the energy storage elements. As a result, if the temperature of the energy storage elements is abnormal, the temperature distribution of the heat transfer medium flowing through the passage space is changed, and the overall temperature is adjusted appropriately.

[0029] (11) The computer program of the present disclosure is a computer program that causes a computer that controls an energy storage system comprising an energy storage device including a plurality of energy storage elements connected to each other, a flow space provided in the energy storage device through which a fluid heat transfer medium that exchanges heat with the plurality of energy storage elements flows, and a flow path adjustment mechanism connected to the flow space that changes the direction in which the heat transfer medium flows through the flow space to execute a process, the computer program to acquire the temperature of the energy storage elements and, according to the acquired temperature, causes the flow path adjustment mechanism to change the direction in which the heat transfer medium flows through the flow space.

[0030] By executing the processing according to the computer program described in (11) above, the computer controls an energy storage system comprising an energy storage device containing multiple energy storage elements, a flow space through which a heat transfer medium flows, and a flow path adjustment mechanism that changes the direction in which the heat transfer medium flows through the flow space. According to the computer program, the computer controls the flow path adjustment mechanism according to the temperature of the energy storage elements to change the direction in which the heat transfer medium flows through the flow space. Through the computer's processing, if the temperature of the energy storage elements is abnormal, the temperature distribution of the heat transfer medium flowing through the flow space is changed, and the overall temperature is adjusted appropriately.

[0031] The present invention will be described in detail below with reference to the drawings illustrating its embodiments. Figure 1 shows an example configuration of an energy storage system 100. The energy storage system 100 includes an energy storage device 1 that includes a plurality of energy storage cells 11. Each energy storage cell 11 corresponds to an energy storage element. Each energy storage cell 11 is a secondary battery. For example, each energy storage cell 11 is a lithium-ion secondary battery. The plurality of energy storage cells 11 included in the energy storage system 100 are connected to each other. In the energy storage device 1, a bank is configured in which a plurality of energy storage cells 11 are connected in series, and multiple banks are connected to each other in parallel. The connection configuration of the plurality of energy storage cells 11 shown in Figure 1 is just one example, and the plurality of energy storage cells 11 may be configured in other ways. Note that a bank may correspond to an energy storage element. A module containing a plurality of energy storage cells 11 is configured, and multiple modules are included in a bank, and a module may correspond to an energy storage element.

[0032] The energy storage system 100 is equipped with a PCS (Power Conditioning System) 6, and the energy storage device 1 is connected to the PCS 6. Multiple energy storage cells 11 included in the energy storage device 1 are connected to the PCS 6. The PCS 21 performs power control such as conversion between AC and DC or voltage conversion. The energy storage device 1 performs charging and discharging as each energy storage cell 11 performs charging and discharging. The energy storage device 1 performs charging and discharging via the PCS 6.

[0033] The energy storage system 100 is installed in vehicles such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). The energy storage device 1 is charged by receiving power from a power generation facility such as an alternator, or power supplied from outside the vehicle, through the PCS 6. The energy storage device 1 also discharges and supplies power to loads such as electric motors inside the vehicle through the PCS 6.

[0034] Alternatively, the energy storage system 100 may be an ESS (Energy Storage System). The PCS 6 is connected to the power grid. Power generation facilities such as solar power generation facilities or wind power generation facilities are connected to the power grid, and power is supplied from the power generation facilities to the energy storage system 100 through the power grid, and power is supplied to the energy storage device 1 through the PCS 6, where the energy storage device 1 is charged. Also, discharge occurs in the energy storage device 1, and power is supplied to the outside of the energy storage system 100. Loads are connected to the power grid, and power is supplied from the PCS 6 to the loads through the power grid. For example, loads are power-consuming facilities such as factories, office buildings, schools, hospitals, restaurants, and airports.

[0035] The energy storage device 1 includes an ammeter 13 for measuring the current flowing through each energy storage cell 11, a voltmeter 14 for measuring the voltage across each energy storage cell 11, and a temperature sensor 15 for measuring the temperature of each energy storage cell 11. Figure 1 shows one ammeter 13, one voltmeter 14, and one temperature sensor 15, but in reality, the energy storage device 1 includes multiple ammeters 13, voltmeters 14, and temperature sensors 15.

[0036] The energy storage device 1 includes a Battery Management Unit (BMU) 12. The Battery Management Unit 12 consists of a processor and a communication unit. An ammeter 13, a voltmeter 14, and a temperature sensor 15 are connected to the Battery Management Unit 12. The Battery Management Unit 12 receives data from the ammeter 13, voltmeter 14, and temperature sensor 15 according to the measurement results. By receiving data from the voltmeter 14 and temperature sensor 15, the Battery Management Unit 12 obtains the current flowing through each energy storage cell 11, the voltage of each energy storage cell 11, and the temperature of each energy storage cell 11. The energy storage device 1 may have multiple Battery Management Units 12.

[0037] The energy storage system 100 includes a flow pipe 2 through which a fluid heat transfer medium flows to regulate the temperature of multiple energy storage cells 11 contained in the energy storage device 1. The flow pipe 2 corresponds to a flow space. The heat transfer medium is, for example, a coolant, more specifically, water. The heat transfer medium may be a fluid other than water. The flow pipe 2 is provided in the energy storage device 1. In Figure 1, the flow pipe 2 is shown as a dashed line. Part of the flow pipe 2 is located close to each energy storage cell 11, and is arranged so that heat exchange can occur between the heat transfer medium flowing through the flow pipe 2 and the energy storage cells 11. Each energy storage cell 11 exchanges heat with the heat transfer medium flowing nearby. The flow pipe 2 may include branches.

[0038] The flow pipe 2 has a first flow port 21 and a second flow port 22. The first flow port 21 and the second flow port 22 are open. One of the first flow port 21 and the second flow port 22 is an inlet for the heat transfer medium to flow in, and the other is an outlet for the heat transfer medium to flow out. The flow pipe 2 is structured to connect the first flow port 21 and the second flow port 22.

[0039] Figure 2 is a schematic diagram showing an example of the external appearance of the energy storage device 1. In Figure 2, only some of the multiple energy storage cells 11 are labeled with reference numerals. The shape of the energy storage cells 11 is a rectangular parallelepiped. Multiple energy storage cells 11 are stacked on top of each other to form a bank, and multiple banks are arranged in a row. The energy storage device 1 is provided with a first flow port 21 and a second flow port 22. As shown in Figure 2, the energy storage cells 11 are configured, for example, in a pack-like shape.

[0040] The energy storage system 100 includes a flow path adjustment mechanism 3 that adjusts the direction in which the heat transfer medium flows through the flow pipe 2, and a temperature control device 4 that adjusts the temperature of the heat transfer medium. The flow path adjustment mechanism 3 is connected to the energy storage device 1, and the temperature control device 4 is connected to the flow path adjustment mechanism 3. The temperature control device 4 is, for example, a chiller and has a pump that brings the heat transfer medium in and out, and a heat radiator that releases heat from the heat transfer medium. The temperature control device 4 adjusts the temperature of the incoming heat transfer medium and discharges the heat transfer medium after its temperature has been adjusted. As the heat transfer medium whose temperature has been adjusted by the temperature control device 4 flows through the flow pipe 2, the temperature of the energy storage cell 11 that exchanges heat with the heat transfer medium is adjusted.

[0041] The flow path adjustment mechanism 3 includes an inlet 35 through which the heat transfer medium flows in and an outlet 36 through which the heat transfer medium flows out. The inlet 35 and outlet 36 are connected to the temperature control device 4. The heat transfer medium that flows out from the temperature control device 4 flows in through the inlet 35, and the heat transfer medium that flows out from the outlet 36 flows into the temperature control device 4. The flow path adjustment mechanism 3 also has a first three-way valve 31, a second three-way valve 32, a third three-way valve 33, and a fourth three-way valve 34. A three-way valve has connection ports to the piping in three directions, and is a valve that can open two of the three connection ports and close the remaining one. In a three-way valve, fluid flows between the two open connection ports, fluid flows into one of the two connection ports and fluid flows out from the other, and no fluid flows in or out through the closed connection port.

[0042] The first three-way valve 31 is connected by piping to the first outlet 21 of the flow pipe 2, the second three-way valve 32, and the fourth three-way valve 34. The second three-way valve 32 is connected by piping to the first three-way valve 31, the third three-way valve 33, and the inlet 35. The third three-way valve 33 is connected by piping to the second outlet 22 of the flow pipe 2, the second three-way valve 32, and the fourth three-way valve 34. The fourth three-way valve 34 is connected by piping to the first three-way valve 31, the third three-way valve 33, and the outlet 36. The flow path adjustment mechanism 3 adjusts the direction in which the heat transfer medium flows through the flow pipe 2 through the operation of the first three-way valve 31, the second three-way valve 32, the third three-way valve 33, and the fourth three-way valve 34.

[0043] The flow path adjustment mechanism 3 adjusts the direction in which the heat transfer medium flows through the flow pipe 2 to either the direction in which the heat transfer medium flows into the first flow port 21 and out of the second flow port 22, or the direction in which the heat transfer medium flows into the second flow port 22 and out of the first flow port 21. The direction in which the heat transfer medium flows into the first flow port 21 and out of the second flow port 22 is defined as the positive direction. When the heat transfer medium flows in the positive direction, the heat transfer medium flows into the flow pipe 2 at the first flow port 21 and out of the flow pipe 2 at the second flow port 22. The direction in which the heat transfer medium flows into the second flow port 22 and out of the first flow port 21 is defined as the reverse direction. If the heat transfer medium is flowing in the reverse direction, it flows into the flow pipe 2 at the second flow port 22 and out of the flow pipe 2 at the first flow port 21.

[0044] Figure 3 is a schematic diagram showing the flow path adjustment mechanism 3 when the direction in which the heat transfer medium flows through the flow pipe 2 is in the positive direction. The first three-way valve 31 opens the connection port connected to the first flow port 21 and the connection port connected to the second three-way valve 32, and closes the connection port connected to the fourth three-way valve 34. The second three-way valve 32 opens the connection port connected to the first three-way valve 31 and the connection port connected to the inlet 35, and closes the connection port connected to the third three-way valve 33. The third three-way valve 33 opens the connection port connected to the second flow port 22 and the connection port connected to the fourth three-way valve 34, and closes the connection port connected to the second three-way valve 32. The fourth three-way valve 34 opens the connection port connected to the third three-way valve 33 and the connection port connected to the outlet 36, while closing the connection port connected to the first three-way valve 31.

[0045] As a result, the flow path between the inlet 35, the second three-way valve 32, the first three-way valve 31, and the first passage port 21 is opened, and the flow path between the second passage port 22, the third three-way valve 33, the fourth three-way valve 34, and the outlet 36 is opened. In addition, the flow path between the first three-way valve 31 and the fourth three-way valve 34 is closed, and the flow path between the second three-way valve 32 and the third three-way valve 33 is closed. The heat transfer medium flows out of the temperature control device 4, flows into the inlet 35, passes through the second three-way valve 32 and the first three-way valve 31, and flows into the passage pipe 2 from the first passage port 21. The heat transfer medium flows through the passage pipe 2, flows out of the passage pipe 2 at the second passage port 22, passes through the third three-way valve 33 and the fourth three-way valve 34, flows out from the outlet 36, and flows into the temperature control device 4. In Figure 3, the direction of flow of the heat transfer medium is indicated by arrows.

[0046] The temperature control device 4 cools the incoming heat transfer medium and discharges the cooled heat transfer medium. The heat transfer medium flowing through the flow pipe 2 exchanges heat with each of the energy storage cells 11. Normally, the energy storage cells 11 generate heat during charging and discharging, the generated heat is absorbed by the heat transfer medium, and the heat-absorbing heat transfer medium is cooled by the temperature control device 4. In this way, the multiple energy storage cells 11 included in the energy storage device 1 are cooled.

[0047] Figure 4 is a schematic diagram showing the flow path adjustment mechanism 3 when the direction of flow of the heat transfer medium through the flow pipe 2 is reversed. The first three-way valve 31 opens the connection port connected to the first flow port 21 and the connection port connected to the fourth three-way valve 34, and closes the connection port connected to the second three-way valve 32. The second three-way valve 32 opens the connection port connected to the third three-way valve 33 and the connection port connected to the inlet 35, and closes the connection port connected to the first three-way valve 31. The third three-way valve 33 opens the connection port connected to the second flow port 22 and the connection port connected to the second three-way valve 32, and closes the connection port connected to the fourth three-way valve 34. The fourth three-way valve 34 opens the connection port connected to the third three-way valve 33 and the connection port connected to the outlet 36, while closing the connection port connected to the first three-way valve 31.

[0048] As a result, the flow path between the inlet 35, the second three-way valve 32, the third three-way valve 33, and the second passage port 22 is opened, and the flow path between the first passage port 21, the first three-way valve 31, the fourth three-way valve 34, and the outlet port 36 is opened. In addition, the flow path between the first three-way valve 31 and the second three-way valve 32 is closed, and the flow path between the third three-way valve 33 and the fourth three-way valve 34 is closed. The heat transfer fluid flows out of the temperature control device 4, flows into the inlet 35, passes through the second three-way valve 32 and the third three-way valve 33, and flows into the passage pipe 2 from the second passage port 22. The heat transfer fluid flows through the passage pipe 2, flows out of the passage pipe 2 at the first passage port 21, passes through the first three-way valve 31 and the fourth three-way valve 34, flows out from the outlet port 36, and flows into the temperature control device 4. In Figure 4, the direction of flow of the heat transfer fluid is indicated by arrows. Similar to the case where a heat transfer medium flows in the forward direction, the multiple energy storage cells 11 included in the energy storage device 1 are cooled.

[0049] The flow path adjustment mechanism 3 may include a check valve. However, using a check valve can increase pressure loss and lead to insufficient flow rate of the heat transfer medium. Furthermore, using a check valve can make the size of the flow path adjustment mechanism 3 excessively large. Therefore, it is preferable that the flow path adjustment mechanism 3 does not include a check valve.

[0050] In this embodiment, although the flow path adjustment mechanism 3 includes four three-way valves, it is also possible to reduce the number of three-way valves to two. For example, the first three-way valve 31 and the third three-way valve 33 may be eliminated, and the second three-way valve 32 may be connected to the first and second flow ports 21 and 22 by piping, and the fourth three-way valve 34 may be connected to the first and second flow ports 21 and 22 by piping. However, in this configuration, even when the flow of the heat transfer medium is stopped, input pressure and return pressure are applied to the three-way valves, which may make switching the three-way valves difficult, and there is a possibility that the heat transfer medium may leak from the closed three-way valves. In the configuration in which the flow path adjustment mechanism 3 includes four three-way valves, the pressure applied to the three-way valves is distributed, allowing for smooth switching, and the possibility of heat transfer medium leaking from the three-way valves is low.

[0051] As shown in Figure 1, the energy storage system 100 is equipped with a control device 5. A flow path adjustment mechanism 3 is connected to the control device 5, and the control device 5 controls the operation of the flow path adjustment mechanism 3. A battery management device 12 is also connected to the control device 5. The first three-way valve 31, second three-way valve 32, third three-way valve 33, and fourth three-way valve 34 included in the flow path adjustment mechanism 3 are solenoid valves. The control device 5 controls the first three-way valve 31, second three-way valve 32, third three-way valve 33, and fourth three-way valve 34 by transmitting control signals to them. The first three-way valve 31, second three-way valve 32, third three-way valve 33, and fourth three-way valve 34 receive control signals from the control device 5 and operate according to the control signals.

[0052] Figure 5 is a block diagram showing an example of the functional configuration of the control device 5. The control device 5 performs a temperature control method. The control device 5 is configured using a computer such as a server device. The control device 5 comprises an arithmetic unit 51, a memory 52, a storage unit 53, a read unit 54, and a communication unit 55. The arithmetic unit 51 is a processor and is configured using, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a multi-core CPU. The arithmetic unit 51 may also be configured using a quantum computer. The memory 52 stores temporary data generated in connection with calculations. The memory 52 is, for example, RAM (Random Access Memory). The read unit 54 reads information from a recording medium 50 such as an optical disc or portable memory. The storage unit 53 is non-volatile and is, for example, a hard disk or a non-volatile semiconductor memory.

[0053] The communication unit 55 is connected to the battery management device 12 and the flow path adjustment mechanism 3 of the energy storage device 1. The communication unit 55 communicates with the battery management device 12 and the flow path adjustment mechanism 3. The battery management device 12 transmits data indicating the current, voltage, and temperature of each energy storage cell 11 to the control device 5, and the communication unit 55 receives the data transmitted from the battery management device 12. The control device 5 transmits control signals from the communication unit 55 to the flow path adjustment mechanism 3 to operate the first three-way valve 31, the second three-way valve 32, the third three-way valve 33, and the fourth three-way valve 34.

[0054] The arithmetic unit 51 causes the reading unit 54 to read the computer program (program product) 531 recorded on the recording medium 50, and stores the read computer program 531 in the storage unit 53. The computer program 531 may be stored in the storage unit 53 in advance, or it may be downloaded from outside the control device 5. In this case, the control device 5 does not need to have a reading unit 54. The arithmetic unit 51 executes processing to realize the functions of the control device 5 according to the computer program 531. The arithmetic unit 51 executes information processing to execute the temperature adjustment method according to the computer program 531.

[0055] The computer program 531 can be deployed on a single computer, at a single site, or distributed across multiple sites and run on multiple computers interconnected by a communication network. That is, the control unit 5 may consist of multiple computers, and the computer program 531 may run on multiple computers connected via a communication network. The control unit 5 may also be configured using a cloud server.

[0056] The processing steps described below for implementing the temperature control method can be performed on multiple computers. Each step can also be performed on different computers. The data used during processing may be stored on multiple computers. Each step can also be performed using a virtual machine. Each step may be executed by multiple processing units. Each step may be executed by different processing units. For example, part of the processing may be performed on one computer, and other parts on other computers.

[0057] The control device 5 controls the flow path adjustment mechanism 3 to perform a temperature adjustment method that adjusts the temperature of the multiple energy storage cells 11 included in the energy storage device 1. The heat transfer medium flows through the flow pipe 2 while cooling each of the energy storage cells 11. When cooling the energy storage cells 11, the heat transfer medium absorbs heat from the energy storage cells 11. As the heat transfer medium flows through the flow pipe 2, its temperature gradually rises, making it more difficult for the heat transfer medium to cool the energy storage cells 11. Near the flow ports 21 and 22 into which the heat transfer medium flows, the temperature of the heat transfer medium is low, so the energy storage cells 11 are easily cooled, and their temperature is kept low. In contrast, near the flow ports out which the heat transfer medium flows out, the temperature of the heat transfer medium is high, making it more difficult for the energy storage cells 11 to cool, and their temperature rises.

[0058] The control device 5 controls the flow path adjustment mechanism 3 to appropriately change the direction in which the heat transfer medium flows through the flow pipe 2 between the forward and reverse directions. The flow path adjustment mechanism 3 changes the state of the first three-way valve 31, the second three-way valve 32, the third three-way valve 33, and the fourth three-way valve 34 in accordance with the control from the control device 5, between a state in which the heat transfer medium flows in the forward direction and a state in which the heat transfer medium flows in the reverse direction. When the direction in which the heat transfer medium flows is changed, the position of the inlet into which the heat transfer medium flows into the flow pipe 2 is reversed, and the temperature distribution of the heat transfer medium flowing through the flow pipe 2 is changed. At the inlet where the heat transfer medium previously flowed out, the heat transfer medium now flows in, and the temperature of the heat transfer medium flowing near the energy storage cell 11 decreases in the vicinity of this inlet, making it easier to cool the energy storage cell 11, and thus lowering the temperature of the energy storage cell 11. By repeatedly changing the direction in which the heat transfer medium flows, the temperature difference between the multiple energy storage cells 11 is reduced, and the temperature of the multiple energy storage cells 11 is made uniform overall.

[0059] Figure 6 is a flowchart showing a first example of the procedure for temperature adjustment processing performed by the control device 5. Hereinafter, steps will be abbreviated as S. The control device 5 performs the following processing by having the calculation unit 51 perform information processing according to the computer program 531. The control device 5 acquires the temperature of each energy storage cell 11 contained in the energy storage device 1 (S11). The temperature sensor 15 measures the temperature of the energy storage cell 11, and the battery management device 12 acquires the temperature measured by the temperature sensor 15 and transmits the temperature data to the control device 5. The control device 5 acquires the temperature of each energy storage cell 11 by receiving the data from the battery management device 12 with the communication unit 55.

[0060] The control device 5 then calculates the difference between the temperature of the energy storage cell 11 located near the first flow port 21 and the temperature of the energy storage cell 11 located near the second flow port 22 (S12). The energy storage cell 11 located near the first flow port 21 is the energy storage cell 11 located closer to the first flow port 21 than to the second flow port 22, for example, the energy storage cell 11 located closest to the first flow port 21. The energy storage cell 11 located near the second flow port 22 is the energy storage cell 11 located closer to the second flow port 22 than to the first flow port 21, for example, the energy storage cell 11 located closest to the second flow port 22. In S12, the calculation unit 51 calculates the absolute value of the difference between the temperature of the energy storage cell 11 located near the first flow port 21 and the temperature of the energy storage cell 11 located near the second flow port 22 as the temperature difference. At this time, the calculation unit 51 may calculate the difference between the average or median temperature of the multiple energy storage cells 11 near the first flow port 21 and the average or median temperature of the multiple energy storage cells 11 near the second flow port 22.

[0061] Next, the control device 5 determines whether the temperature difference between the energy storage cell 11 located near the first flow port 21 and the energy storage cell 11 located near the second flow port 22 is greater than or equal to a predetermined reference temperature difference (S13). The value of the reference temperature difference is stored in the storage unit 53 in advance. In S13, the calculation unit 51 determines whether the temperature difference calculated in S12 is greater than or equal to the reference temperature difference. If the temperature difference is less than the reference temperature difference (S13: NO), the control device 5 terminates the process.

[0062] If the temperature difference is greater than or equal to the reference temperature difference (S13: YES), the control device 5 changes the direction in which the heat transfer medium flows (S14). In S14, the calculation unit 51 transmits a control signal from the communication unit 55 to the flow path adjustment mechanism 3 in order to change the direction in which the heat transfer medium flows. If the direction in which the heat transfer medium has been flowing up to that point has been the forward direction, the calculation unit 51 transmits a control signal to reverse the direction in which the heat transfer medium flows. That is, the calculation unit 51 transmits a control signal to the flow path adjustment mechanism 3 to change the state of the flow path adjustment mechanism 3 from a state in which the heat transfer medium flows in the forward direction to a state in which the heat transfer medium flows in the reverse direction. In response to the control signal, the first three-way valve 31, the second three-way valve 32, the third three-way valve 33, and the fourth three-way valve 34 operate, and the heat transfer medium flows in the reverse direction.

[0063] If the direction in which the heat transfer medium is flowing is reversed, the calculation unit 51 sends a control signal to change the direction in which the heat transfer medium flows to the forward direction. That is, the calculation unit 51 sends a control signal to the flow path adjustment mechanism 3 to change the state of the flow path adjustment mechanism 3 from a state in which the heat transfer medium flows in reverse to a state in which the heat transfer medium flows in the forward direction. In response to the control signal, the first three-way valve 31, the second three-way valve 32, the third three-way valve 33, and the fourth three-way valve 34 operate, and the heat transfer medium flows in the forward direction. After S14 is completed, the control device 5 terminates processing.

[0064] The control device 5 repeats the processes S11 to S14. The processes S11 to S14 change the direction of the heat transfer medium flow when there is a large difference between the temperature of the easily cooled energy storage cells 11 and the difficult-to-cool energy storage cells 11. The temperature distribution of the heat transfer medium changes, and the positions of the easily cooled energy storage cells 11 and the difficult-to-cool energy storage cells 11 are swapped. Even after the processes S11 to S14 are performed, it takes time for the direction of the heat transfer medium flow to actually change and for the temperature of the energy storage cells 11 to change. The reference temperature difference may be determined considering the time it takes for the temperature of the energy storage cells 11 to actually change.

[0065] As processes S11 to S14 are repeated, the temperature difference between the multiple energy storage cells 11 decreases, and the temperature of the multiple energy storage cells 11 becomes uniform overall. The higher the temperature of an energy storage cell 11, the more it deteriorates. By reducing the temperature difference between the multiple energy storage cells 11, rapid deterioration of some energy storage cells 11 is prevented, and the progression of deterioration of the multiple energy storage cells 11 is leveled out.

[0066] Figure 7 is a flowchart showing a second example of the procedure for temperature adjustment performed by the control device 5. The control device 5 obtains the temperature of each energy storage cell 11 included in the energy storage device 1 (S21). The control device 5 then determines whether the temperature of the energy storage cell 11 is above a predetermined upper limit temperature (S22). The upper limit temperature is the design upper limit temperature at which the energy storage cell 11 can be charged and discharged, or a preset upper limit temperature. The value of the upper limit temperature is stored in the storage unit 53 in advance.

[0067] In S22, the calculation unit 51 determines whether the temperature of the energy storage cells 11 located near the outlet from which the heat transfer medium is flowing out among the first outlet 21 and the second outlet 22 is above the upper limit temperature. For example, the calculation unit 51 determines whether the temperature of the energy storage cell 11 located closest to the outlet from which the heat transfer medium is flowing out is above the upper limit temperature. The calculation unit 51 may also determine whether the average or median temperature of multiple energy storage cells 11 located near the outlet from which the heat transfer medium is flowing is above the upper limit temperature. The calculation unit 51 may also determine whether the temperature of any of the multiple energy storage cells 11 included in the energy storage device 1 is above the upper limit temperature.

[0068] If the temperature of the energy storage cell 11 is below the upper limit temperature (S22: NO), the control device 5 terminates the process. If the temperature of the energy storage cell 11 is above the upper limit temperature (S22: YES), the control device 5 changes the direction in which the heat transfer medium flows (S23). After S23 is completed, the control device 5 terminates the process.

[0069] The control device 5 repeats the processes S21 to S23. The processes S21 to S23 change the direction of the heat transfer medium flow if the temperature of the energy storage cells 11 is above the upper limit temperature. The temperature distribution of the heat transfer medium is altered, swapping the positions of energy storage cells 11 that are easily cooled with those that are difficult to cool. Energy storage cells 11 that were difficult to cool and whose temperature was above the upper limit temperature become easier to cool, causing their temperature to decrease and fall below the upper limit temperature. By repeating the processes S21 to S23, the temperature of the energy storage cells 11 is prevented from significantly exceeding the upper limit temperature, thus preventing the energy storage cells 11 from becoming unable to charge or discharge due to high temperature, and preventing the energy storage cells 11 from rapidly degrading.

[0070] If the temperature of the energy storage cell 11 is too low, its charge and discharge performance will deteriorate. The energy storage device 1 can heat the energy storage cell 11 by maintaining the temperature of the heat transfer medium at a certain temperature using the temperature control device 4. Figure 8 is a flowchart showing a third example of the procedure for temperature adjustment performed by the control device 5. The control device 5 obtains the temperature of each energy storage cell 11 included in the energy storage device 1 (S31). The control device 5 then determines whether the temperature of the first energy storage cell located near the outlet into which the heat transfer medium flows, among the first and second outlets 21 and 22, exceeds a predetermined lower limit temperature (S32). The lower limit temperature is the design lower limit temperature at which the energy storage cell 11 can be charged and discharged. The value of the lower limit temperature is stored in advance in the storage unit 53.

[0071] In S32, the calculation unit 51 determines whether the temperature of the first energy storage cell exceeds the lower limit temperature, for example, by designating the energy storage cell 11 closest to the inlet into which the heat transfer medium flows as the first energy storage cell. The calculation unit 51 may also use the average or median temperature of multiple energy storage cells 11 located near the inlet into which the heat transfer medium flows as the temperature of the first energy storage cell. If the temperature of the first energy storage cell does not exceed the lower limit temperature (S32: NO), the control device 5 terminates the process.

[0072] If the temperature of the first energy storage cell exceeds the lower limit temperature (S32: YES), the control device 5 determines whether the temperature of the second energy storage cell located near the outlet from which the heat transfer medium is flowing out among the first and second outlets 21 and 22 is below the lower limit temperature (S33). In S33, the calculation unit 51 determines whether the temperature of the second energy storage cell is below the lower limit temperature, for example, by designating the energy storage cell 11 located closest to the outlet from which the heat transfer medium is flowing as the second energy storage cell. The calculation unit 51 may also use the average or median temperature of the temperatures of multiple energy storage cells 11 located near the outlet from which the heat transfer medium is flowing as the temperature of the second energy storage cell.

[0073] If the temperature of the second energy storage cell is not below the lower limit temperature (S33: NO), the control device 5 terminates the process. If the temperature of the second energy storage cell is below the lower limit temperature (S33: YES), the control device 5 changes the direction in which the heat transfer medium flows (S34). S32 and S33 may be executed in the reverse order. After S34 is completed, the control device 5 terminates the process.

[0074] The control device 5 repeats the processes from S31 to S34. If the temperature of the first energy storage cell exceeds the lower limit temperature, the energy storage cell 11 is sufficiently heated to a chargeable and dischargeable temperature near the inlet through which the heat transfer medium flows. If the temperature of the second energy storage cell is below the lower limit temperature, the energy storage cell 11 is not sufficiently heated near the inlet through which the heat transfer medium flows out, and the temperature of the energy storage cell 11 is not at a chargeable and dischargeable temperature. By changing the direction in which the heat transfer medium flows in this state, the energy storage cell 11 that was not sufficiently heated is heated, and the temperature of the energy storage cell 11 rises to a chargeable and dischargeable temperature. In this way, in S31 to S34, when the temperature of some of the energy storage cells 11 falls below the chargeable and dischargeable temperature, the temperature of the energy storage cells 11 is raised to a chargeable and dischargeable temperature by changing the direction in which the heat transfer medium flows, making it possible for multiple energy storage cells 11 to perform charging and discharging as a whole. Therefore, even when the temperature is too low, the energy storage system 100 can effectively heat the multiple energy storage cells 11 and perform its charging and discharging performance.

[0075] The control device 5 can also change the direction of the flow of the heat transfer medium and, when it detects that the temperature of all energy storage elements has temporarily exceeded the lower limit temperature, it can perform charging and discharging of the energy storage cells 11. In this process, the control device 5 can continuously perform charging and discharging by utilizing the heat generated by the energy storage cells 11, so that the temperature of all energy storage cells 11 exceeds the lower limit temperature.

[0076] Figure 9 is a flowchart showing a fourth example of the procedure for temperature adjustment performed by the control device 5. The control device 5 obtains the temperature of each energy storage cell 11 contained in the energy storage device 1 (S41). The control device 5 then calculates the current value that can be charged and discharged in the energy storage device 1 (S42). The chargeable current value is the value of the current that the energy storage device 1 can supply when charging and discharging. The current that an energy storage cell 11 can supply when charging and discharging is determined by the temperature of the energy storage cell 11. In S42, the calculation unit 51 calculates the current that each energy storage cell 11 can supply when charging and discharging based on the temperature of each energy storage cell 11, and calculates the chargeable current value in the energy storage device 1 based on the current that each energy storage cell 11 can supply. For example, a table recording the relationship between the temperature of an energy storage cell 11 and the current that an energy storage cell 11 can supply is stored in the storage unit 53, and the calculation unit 51 refers to the table to calculate the current that an energy storage cell 11 can supply.

[0077] The control device 5 then determines whether the current value that can be charged and discharged by the energy storage device 1 is less than a predetermined lower limit current value (S43). The lower limit current value is a preset current value and is stored in the storage unit 53 in advance. If the current value that can be charged and discharged by the energy storage device 1 is not less than the lower limit current value (S43: NO), the control device 5 terminates the process. If the current value that can be charged and discharged by the energy storage device 1 is less than the lower limit current value (S43: YES), the control device 5 changes the direction in which the heat transfer medium flows (S44). After S44 is completed, the control device 5 terminates the process.

[0078] The control device 5 repeats the processes from S41 to S44. If the temperature of the energy storage cell 11 is too low, the current that the energy storage cell 11 can supply during charging and discharging decreases, and the current value that can be charged and discharged by the energy storage device 1 decreases. By repeating the processes from S41 to S44, the temperatures of the multiple energy storage cells 11 included in the energy storage device 1 are adjusted to be nearly uniform, and the current value that can be charged and discharged by the energy storage device 1 can be kept high.

[0079] Figure 10 is a flowchart showing a fifth example of the procedure for temperature control processing performed by the control device 5. The control device 5 acquires the data necessary to calculate the degree of degradation of each energy storage cell 11 (S51). The degree of degradation is information that represents the degree of degradation of the energy storage cell 11. The degree of degradation is, for example, the remaining capacity or internal resistance of the energy storage cell 11. The data necessary to calculate the degree of degradation is, for example, the current flowing through the energy storage cell 11 and the voltage across the energy storage cell 11. The ammeter 13 measures the current of the energy storage cell 11, the voltmeter 14 measures the voltage of the energy storage cell 11, and the battery management device 12 acquires the measured current and voltage and transmits the current and voltage data to the control device 5. The control device 5 acquires the current and voltage of each energy storage cell 11 by receiving the data from the battery management device 12 with the communication unit 55.

[0080] The control device 5 then calculates the degree of degradation of each energy storage cell 11 (S52). In S52, for example, the calculation unit 51 calculates the remaining capacity of the energy storage cell 11 as the degree of degradation based on the history of the current and voltage of the energy storage cell 11. The smaller the remaining capacity, the higher the degree of degradation of the energy storage cell 11. For example, the calculation unit 51 calculates the internal resistance of the energy storage cell 11 as the degree of degradation based on the current and voltage of the energy storage cell 11. The larger the internal resistance, the higher the degree of degradation of the energy storage cell 11. In S52, the control device 5 may calculate a quantity other than remaining capacity or internal resistance as the degree of degradation of the energy storage cell 11. For example, the control device 5 may calculate SOH (State of Health) as the degree of degradation. In addition, the control device 5 may acquire data other than the current and voltage of the energy storage cell 11 as data necessary for calculating the degree of degradation in S51.

[0081] The control device 5 then calculates the difference between the degradation degree of the energy storage cells 11 located near the first flow port 21 and the degradation degree of the energy storage cells 11 located near the second flow port 22 (S53). In S53, the calculation unit 51 calculates, for example, the absolute value of the difference between the degradation degree of the energy storage cell 11 located closest to the first flow port 21 and the degradation degree of the energy storage cell 11 located closest to the second flow port 22 as the difference in degradation degrees. The calculation unit 51 may also calculate the difference between the average or median degradation degree of multiple energy storage cells 11 located near the first flow port 21 and the average or median degradation degree of multiple energy storage cells 11 located near the second flow port 22. In S52, the control device 5 may calculate only the degradation degrees of the energy storage cells 11 to be used in the calculation in S53.

[0082] The control device 5 then determines whether the difference between the degradation level of the energy storage cell 11 located near the first flow port 21 and the degradation level of the energy storage cell 11 located near the second flow port 22 is greater than or equal to a predetermined threshold (S54). The threshold is stored in advance in the storage unit 53. In S54, the calculation unit 51 determines whether the difference in degradation levels calculated in S53 is greater than or equal to the threshold.

[0083] If the difference in the degree of degradation is less than the threshold (S54: NO), the control device 5 terminates the process. If the difference in the degree of degradation is greater than or equal to the threshold (S54: YES), the control device 5 changes the direction in which the heat transfer medium flows (S55). After S55 is completed, the control device 5 terminates the process.

[0084] The control device 5 repeats the processes from S51 to S55. During the processes from S51 to S55, if the difference in the degree of degradation of the energy storage cells 11 exceeds a threshold, the direction of the flow of the heat transfer medium is changed. The temperature distribution of the heat transfer medium is altered, and the positions of energy storage cells 11 that are easily cooled and those that are difficult to cool are swapped. The temperature of the energy storage cells 11 that are difficult to cool rises, and degradation progresses more rapidly. When the difference in the degree of degradation is large, the direction of the flow of the heat transfer medium is changed, making it easier to cool the energy storage cells 11 that were degrading, and thus suppressing the progression of degradation. In this way, the degree of degradation of the multiple energy storage cells 11 included in the energy storage device 1 is adjusted to be nearly uniform.

[0085] Since it takes a longer time for the difference in degradation to exceed a threshold compared to the time it takes for a temperature difference to occur, changing the direction of flow of the heat transfer medium based on the degradation level reduces the frequency of direction changes compared to changing the direction based on temperature. As a result, the frequency of operation of the first three-way valve 31, second three-way valve 32, third three-way valve 33, and fourth three-way valve 34 decreases. This makes it possible to use valves with reduced durability and lower costs as the first three-way valve 31, second three-way valve 32, third three-way valve 33, and fourth three-way valve 34.

[0086] The control device 5 may execute multiple processes from S11 to S14, S21 to S23, S31 to S34, S41 to S44, and S51 to S55 in parallel, or it may execute only one of these processes. The control device 5 may also control the flow path adjustment mechanism 3 by processes other than S11 to S14, S21 to S23, S31 to S34, S41 to S44, or S51 to S55. For example, the control device 5 may perform a process to periodically change the direction in which the heat transfer medium flows through the flow pipe 2 to the flow path adjustment mechanism 3, or it may perform a process to change the direction in which the heat transfer medium flows through the flow path adjustment mechanism 3 at a specific time.

[0087] As described in detail above, in this embodiment, the energy storage system 100 comprises an energy storage device 1, a flow pipe 2 through which a heat transfer medium that exchanges heat with a plurality of energy storage cells 11 contained in the energy storage device 1 flows, and a flow path adjustment mechanism 3. The flow path adjustment mechanism 3 changes the direction in which the heat transfer medium flows through the flow pipe 2. Energy storage cells 11 located near the point where the heat transfer medium flows out of the flow pipe 2 are less easily cooled than energy storage cells 11 located near the point where the heat transfer medium flows into the flow pipe 2. By appropriately changing the direction in which the heat transfer medium flows, the temperature distribution of the heat transfer medium is changed, and the plurality of energy storage cells 11 contained in the energy storage device 1 are effectively cooled. The temperature difference between the plurality of energy storage cells 11 is reduced, and the temperature of the plurality of energy storage cells 11 is made uniform overall. Similarly, the energy storage system 100 can also effectively heat the plurality of energy storage cells 11. In this case as well, the temperature difference between the plurality of energy storage cells 11 is reduced, and the temperature of the plurality of energy storage cells 11 is made uniform overall.

[0088] Thus, the energy storage system 100 can effectively regulate multiple energy storage cells 11 without requiring numerous parallel flow pipes 2. In other words, the energy storage system 100 can regulate the temperature of multiple energy storage cells 11 to the same extent as conventional systems, but with fewer flow pipes 2. Reducing the number of flow pipes 2 lowers the cost of the energy storage system 100, and also reduces the likelihood of insufficient space for the flow pipes 2 in the structure. The reduction in the number of flow pipes 2 also reduces the number of connection points, thus lowering the frequency of failures in the energy storage system 100.

[0089] In this embodiment, the energy storage system 100 is shown to have a single energy storage device 1 and a flow pipe 2. Alternatively, the energy storage system 100 may have multiple energy storage devices 1 and flow pipes 2. Multiple flow pipes 2 may be connected to the same flow path adjustment mechanism 3. The energy storage system 100 may have multiple flow path adjustment mechanisms 3, with each flow path adjustment mechanism 3 connected to a flow pipe 2, and each flow path adjustment mechanism 3 may individually adjust the direction in which the heat transfer medium flows through the flow pipe 2. If the thermal environment differs among the multiple energy storage devices 1, such as when some of the energy storage devices 1 are affected by heat caused by sunlight, the temperature of the energy storage cells 11 can be effectively adjusted according to the thermal environment by having each flow path adjustment mechanism 3 make individual adjustments.

[0090] In this embodiment, the flow space is shown as a flow pipe 2, but the flow space may take a form other than a flow pipe 2. Figure 11 is a schematic cross-sectional view showing an energy storage device 1 in which the flow space is a cavity. The energy storage device 1 includes a housing 16 that houses a plurality of energy storage cells 11 inside, and the inside of the housing 16 is a cavity 23. A first flow port 21 and a second flow port 22 are formed in the housing 16, and the area is sealed except for the first flow port 21 and the second flow port 22. A plurality of energy storage cells 11 are arranged in the cavity 23, and a fluid heat transfer medium 24 is also filled inside. The heat transfer medium 24 flows into the cavity 23 from one of the first flow port 21 and the second flow port 22, flows through the cavity 23, and flows out from one of the first flow port 21 and the second flow port 22. Figure 11 shows an example where the first outlet 21 is the outlet and the second outlet 22 is the inlet, with arrows indicating the direction of flow of the heat transfer medium 24. Although Figure 11 shows an example where there are gaps in the cavity 23 where the heat transfer medium 24 is not filled, the heat transfer medium 24 may be filled without any gaps in the cavity 23. The configuration of the other parts of the energy storage system 100 is similar.

[0091] Each energy storage cell 11 is immersed in the heat transfer medium 24 within the cavity 23 and exchanges heat with the heat transfer medium 24. Compared to the configuration in which the heat transfer medium flows through the flow pipe 2, the energy storage cells 11 exchange heat with the heat transfer medium 24 more directly over a wider area, and the temperature of the energy storage cells 11 is efficiently regulated. Even in this configuration, there is a temperature difference in the heat transfer medium 24 near the inlet and near the outlet. The energy storage system 100 performs a process to change the direction in which the heat transfer medium 24 flows within the cavity 23. By changing the direction in which the heat transfer medium 24 flows, the temperature distribution of the heat transfer medium is changed, and the temperatures of the multiple energy storage cells 11 are effectively regulated. The temperature difference between the multiple energy storage cells 11 is reduced, and the temperatures of the multiple energy storage cells 11 are made more uniform overall.

[0092] In this embodiment, the energy storage system 100 is shown to be equipped with a temperature control device 4. Alternatively, the energy storage system 100 may be in a configuration that does not include a temperature control device 4. For example, the energy storage system 100 may be in a configuration in which a heat transfer medium is supplied to the inlet 35 of the flow path adjustment mechanism 3, and the heat transfer medium that flows out from the outlet 36 is discarded.

[0093] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. That is, embodiments obtained by combining technical means that have been appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

[0094] The matters described in each embodiment can be combined with each other. Furthermore, the independent and dependent claims described in the claims can be combined with each other in any combination, regardless of the form of reference. Moreover, although the claims use a form in which claims referencing two or more other claims (multi-claim form), it is not limited to this. A form in which multi-claims referencing at least one multi-claim (multi-multi-claim) may also be used. [Explanation of symbols]

[0095] 100 Energy Storage Systems 1. Energy storage device 11 energy storage cells 2 Flow pipe (flow space) 21 1st flow pipe 22 2nd flow pipe 23 Cavity (flow space) 24 Heat medium 3. Flow path adjustment mechanism 31. First tricuspid valve 32. Second tricuspid valve 33. Third tricuspid valve 34. Fourth tricuspid valve 35 Inlet 36 week exit 4 Temperature adjustment device 5 Control device 50 Recording media 51 Arithmetic section 53 Storage section 531 Computer Programs

Claims

1. A power storage device including multiple interconnected energy storage elements, The aforementioned energy storage device is provided with a passage space through which a fluid heat transfer medium that exchanges heat with a plurality of the aforementioned energy storage elements flows, A flow path adjustment mechanism is connected to the aforementioned flow space and changes the direction in which the heat transfer medium flows through the flow space. A battery storage system equipped with the following features.

2. The system further includes a temperature control device that adjusts the temperature of the incoming heat transfer medium and discharges the heat transfer medium with its temperature adjusted. The temperature control device is connected to the flow path adjustment mechanism, The heat transfer fluid that flows out of the flow space flows into the temperature control device through the flow path adjustment mechanism, and the heat transfer fluid that flows out of the temperature control device flows back into the flow space through the flow path adjustment mechanism. The energy storage system according to claim 1.

3. The flow space has a first flow port and a second flow port through which the heat transfer medium flows in and out from the other side. The flow path adjustment mechanism includes an inlet through which the heat transfer medium flows in, an outlet through which the heat transfer medium flows out, a first three-way valve, a second three-way valve, a third three-way valve, and a fourth three-way valve. The first three-way valve is connected to the first flow port, the second three-way valve, and the fourth three-way valve. The second three-way valve is connected to the first three-way valve, the third three-way valve, and the inlet. The third three-way valve is connected to the second flow port, the second three-way valve, and the fourth three-way valve. The fourth three-way valve is connected to the first three-way valve, the third three-way valve and the outlet, The aforementioned flow path adjustment mechanism is By switching between a state in which the flow path between the inlet, the second three-way valve, the first three-way valve, and the first passage port is open, the flow path between the second passage port, the third three-way valve, the fourth three-way valve, and the outlet is open, the flow path between the first three-way valve and the fourth three-way valve is closed, and the flow path between the second three-way valve and the third three-way valve is closed, the direction in which the heat transfer medium flows can be changed. The energy storage system according to claim 1.

4. The control device further comprises a control device for controlling the flow path adjustment mechanism, The control device is The temperature of the energy storage element is obtained, Depending on the acquired temperature, the flow path adjustment mechanism is instructed to change the direction in which the heat transfer medium flows. The energy storage system according to any one of claims 1 to 3.

5. The aforementioned flow space has two flow ports through which the heat transfer medium flows in and out from the other, The control device is If the temperature difference between the energy storage element located near one of the two flow ports and the energy storage element located near the other flow port exceeds a predetermined value, the flow path adjustment mechanism is instructed to change the direction in which the heat transfer medium flows. The energy storage system according to claim 4.

6. The aforementioned flow space has two flow ports through which the heat transfer medium flows in and out from the other, The control device is If the temperature of the energy storage element located near the outlet from which the heat transfer medium is flowing out of the two outlets exceeds a predetermined upper limit temperature, the flow path adjustment mechanism will change the direction in which the heat transfer medium flows. The energy storage system according to claim 4.

7. The aforementioned flow space has two flow ports through which the heat transfer medium flows in and out from the other, The control device is If the temperature of the energy storage element located near the outlet into which the heat transfer medium flows exceeds a predetermined lower limit, and the temperature of the energy storage element located near the outlet out which the heat transfer medium flows is below the lower limit, the flow path adjustment mechanism is instructed to change the direction in which the heat transfer medium flows. The energy storage system according to claim 4.

8. The control device is Based on the temperature of the energy storage element, the current value that can be charged and discharged by the energy storage device is calculated. If the calculated current value is less than a predetermined value, the flow path adjustment mechanism is instructed to change the direction in which the heat transfer medium flows. The energy storage system according to claim 4.

9. Further equipped with a control device, The aforementioned flow space has two flow ports through which the heat transfer medium flows in and out from the other, The control device is The degree of deterioration of the energy storage element located closer to one of the two flow ports is identified, and the degree of deterioration of the energy storage element located closer to the other flow port is identified. If the difference between the degree of deterioration of the energy storage element located near one of the aforementioned flow inlets and the degree of deterioration of the energy storage element located near the other flow inlet exceeds a predetermined value, the flow path adjustment mechanism will cause the direction in which the heat transfer medium flows to change. The energy storage system according to any one of claims 1 to 3.

10. In a power storage device including a plurality of interconnected energy storage elements, a temperature control method is provided in the power storage device and uses a flow space through which a fluid heat transfer medium that exchanges heat with the plurality of energy storage elements flows to adjust the temperature of the energy storage elements, The temperature of the energy storage element is obtained, Depending on the acquired temperature, the direction in which the heat transfer medium flows through the passage space is changed. Temperature adjustment method.

11. A computer program that causes a computer to execute a process for controlling a power storage system comprising: a power storage device including a plurality of interconnected power storage elements; a flow space provided in the power storage device through which a fluid heat transfer medium that exchanges heat with the plurality of power storage elements flows; and a flow path adjustment mechanism connected to the flow space that changes the direction in which the heat transfer medium flows through the flow space; The temperature of the energy storage element is obtained, Depending on the acquired temperature, the flow path adjustment mechanism causes the direction in which the heat transfer medium flows through the flow space to change. A computer program that instructs a computer to perform a process.

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