Storage battery system

Abstract

The present invention comprises: a power storage unit (10) having a plurality of storage battery modules (12) that are connected in parallel and a BMS (15) that controls input / output amounts of each of the plurality of storage battery modules (12) and measures the internal resistance thereof; and a control determination unit (21) that, on the basis of the amounts of heat generated by each of the plurality of storage battery modules (12) calculated from the internal resistance of each of the plurality of storage battery modules (12) relative to the input / output amounts of power required for the power storage unit (10), controls the BMS (15) to adjust the distribution of the input / output amounts to / from each of the plurality of storage battery modules (12).

Description

Battery storage system

[0001] The present disclosure relates to a battery storage system.

[0002] In a storage battery system, a technology has been proposed to suppress deterioration of the storage battery by managing the temperature of the storage battery using a temperature control device such as an air conditioner based on the temperature or charging rate (SOC: State Of Charge) of the storage battery (see, for example, Patent Document 1).

[0003] JP 2019-9960 A (paragraphs 0025 to 0040, FIG. 1, paragraphs 0044 to 0055, FIG. 2, FIG. 3)

[0004] On the other hand, while a large number of storage battery modules are often installed in a storage battery system, Patent Document 1 does not take into consideration the temperature distribution among the modules, which makes it difficult to properly manage the temperature of some modules and to sufficiently suppress deterioration.

[0005] The present disclosure discloses a technique for solving the above-mentioned problems, and aims to suppress the temperature distribution that occurs between modules and extend the life of the system.

[0006] The storage battery system of the present disclosure is characterized by comprising: a storage unit having a plurality of storage battery modules each composed of a plurality of storage battery cells and connected in parallel to each other; an input / output control unit that controls the input / output amount of each of the plurality of storage battery modules and measures the internal resistance; and a distribution adjustment unit that controls the input / output control unit based on the heat generation amount of each of the plurality of storage battery modules calculated from the internal resistance of each of the plurality of storage battery modules in relation to the input / output amount of power required for the storage unit, and adjusts the distribution of the input / output amount to each of the plurality of storage battery modules.

[0007] According to the storage battery system of the present disclosure, control is performed based on the characteristics of each module, so the degree of deterioration between modules can be equalized, thereby extending the life of the storage battery system.

[0008] FIG. 1 is a block diagram for explaining the configuration of a storage battery system according to a first embodiment. FIG. 2 is a block diagram for explaining the configuration of a control determination unit of the storage battery system according to the first embodiment. FIG. 3 is a flowchart for explaining a process of setting a control mode among the operations of the storage battery system according to the first embodiment. FIG. 4 is a flowchart for explaining the operation of a normal control mode among the operations of the storage battery system according to the first embodiment. FIG. 5 is a flowchart for explaining the operation of a low temperature control mode among the operations of the storage battery system according to the first embodiment. FIG. 6 is a flowchart for explaining the operation when transitioning to an internal input / output mode in the low temperature control mode among the operations of the storage battery system according to the first embodiment. FIG. 7 is a flowchart for explaining the operation of a normal control mode among the operations of the storage battery system according to the second embodiment. FIG. 8 is a block diagram showing an example of a hardware configuration of a part that executes arithmetic processing in a storage battery system of the present disclosure.

[0009] 1 to 6 are diagrams illustrating the configuration and operation of a battery system according to a first embodiment. Fig. 1 is a block diagram showing the battery system together with a load and a power grid to which it is connected, and Fig. 2 is a block diagram of a control determination unit that controls the input and output of power from each of a plurality of battery modules that make up the battery system.

[0010] Fig. 3 is a flowchart illustrating the process of setting the control mode in the operation of the battery storage system, Fig. 4 is a flowchart illustrating the operation of the normal control mode out of the two main control modes, Fig. 5 is a flowchart illustrating the operation of the low temperature control mode, and Fig. 6 is a flowchart illustrating the operation when the low temperature control mode is switched to the internal input / output mode.

[0011] 1 , the storage battery system 1 of the present disclosure is connected to a power grid 91 and an external load (load 92) via a power converter 93, receives power from the power grid 91 during charging, and outputs power to the load 92 during discharging. Broadly speaking, the system is comprised of a power storage unit 10 that stores DC power and a control unit 20 that controls the operation of the power storage unit 10.

[0012] The power storage unit 10 is configured by connecting n (n≧2) storage battery racks 11 in parallel, each of which has m (m≧1) storage battery cells 13 connected in series and a BMS (Battery Management System) 15. When distinguishing between the individual storage battery modules 12, they are represented by adding a hyphen and a symbol, such as module 12-1, ..., module 12-n.

[0013] The control unit 20 includes a control determination unit 21 that determines the control content based on the state of each storage battery module 12. The control unit 20 also includes a temperature adjustment device 22 that adjusts the temperature of the storage battery module 12, and a system distributor 23 that distributes power between two connection systems provided between the power storage unit 10 and the power converter 93.

[0014] Each storage battery module 12 is provided with a temperature measurement sensor 14 that measures the temperature (module temperature) of the storage battery module 12. The storage battery module 12 also includes a positive wiring 16P for electrical connection to the BMS 15 and a negative wiring 17N for connection to a grounded reference wiring 18N.

[0015] The temperature measurement sensor 14 measures the module temperature and outputs a temperature measurement signal to the control determination unit 21. At least one temperature measurement sensor 14 is provided at any position within the storage battery module 12.

[0016] Each BMS 15 has one end connected to the positive wiring 16P of the storage battery module 12 and the other end connected to the power line 18P via the positive wiring 17P. Each BMS 15 includes a unit for measuring the voltage, current, or internal resistance of the storage battery module 12 or the storage battery cell 13. The BMS 15 receives a command value for the amount of power input / output to / from the storage battery module 12 to which it is connected from the control determination unit 21, and controls the power input / output to / from the storage battery module 12. The BMS 15 also measures the voltage, current, or internal resistance of the storage battery module 12, and outputs a measurement signal to the control determination unit 21.

[0017] The storage battery cells 13 are power storage devices that can be repeatedly charged and discharged, such as lithium ion batteries, electric double layer capacitors, lead storage batteries, etc. The number of storage battery cells 13 that make up the storage battery modules 12, or the number of storage battery modules 12, is set to an optimal number in series or parallel depending on the purpose of using the storage battery system 1.

[0018] The battery rack 11 is, for example, a metal outer box, and is connected to a power converter 93 via a power line 10p connected to a positive terminal 15p of the BMS 15. The power converter 93 is connected to a power system 91, such as a commercial power system, or a load 92. When the power converter 93 is connected to the power system 91, power is input from the power system 91 via the power line to the power converter 93 during charging, and power is output to the power system 91 via the power line during discharging. When the power converter 93 is connected to a load 92 that can generate and drive electricity, power is input from the load 92 during charging, for example, and power is output to the load during discharging.

[0019] As shown in FIG. 2 , the control determination unit 21 includes a signal processing unit 211, a communication unit 212, and a memory 213. The signal processing unit 211 determines each step of a control process (described later) based on output signals from the temperature measurement sensor 14, which measures the temperature of the storage battery module 12, and the BMS 15. The communication unit 212 receives the output signal from the temperature measurement sensor 14, and outputs a control determination signal to the EMS 94. The communication unit 212 also outputs a command value for the amount of power input / output to / from the storage battery module 12 to the BMS 15. The memory 213 stores values ​​calculated by the signal processing unit 211, as well as previously input setting values ​​and thresholds (such as a first threshold, second threshold, third threshold, module control reference number, and tolerance value, which will be described later).

[0020] The EMS 94 outputs an output control signal for the temperature adjustment device 22 or an input / output control signal for the power converter 93 based on the control determination signal output from the control determination unit 21. The temperature adjustment device 22 is installed to cool the space within the storage battery system 1 and the plurality of storage battery modules 12, and is, for example, an air conditioning device such as a fan or an air conditioner.

[0021] The power converter 93 may be, for example, an inverter that converts AC power to DC power, a DC-DC converter that converts DC power of a given voltage value to DC power of another voltage value, or an electric circuit device that combines these. For example, for a load 92 that operates on AC and an AC power system 91, the DC power of the storage battery system 1 is converted into AC power by the power converter 93, which is an inverter, and then supplied to the load 92 that operates on DC. Alternatively, for a load 92 that operates on DC, the DC power of the storage battery system 1 is converted into DC power of a desired voltage value by the power converter 93, which is a DC-DC converter, and then supplied to the load 92.

[0022] 1 illustrates a case in which the storage battery system 1 outputs to the load 92 via a power converter 93, but this is not limiting. For example, if the voltage of the DC output of the storage battery system 1 is the same as the operating voltage of the load 92, which is a DC motor, the storage battery system 1 may be directly connected to the load 92. Furthermore, if the power grid 91 is DC and voltage conversion is required, the DC-DC converter power converter 93 may convert the voltage to the desired voltage and input and output DC power. If voltage conversion is not required, DC power may be input and output directly between the power converter 93 and the storage battery system 1.

[0023] Next, based on the above-described configuration, the operation of the storage battery system 1 according to the first embodiment will be described. First, the determination of the control mode, mainly performed by the control determination unit 21, will be described with reference to the flowchart of FIG.

[0024] The control determination unit 21 first receives a temperature measurement signal indicating the module temperature of each of the plurality of storage battery modules 12 output from the temperature measurement sensor 14 (step S100). Next, the control determination unit 21 compares the module temperature of each of the plurality of storage battery modules 12 with a first threshold value (step S110). For example, if the standard operating temperature of the storage battery module 12 or storage battery cell 13 is 25°C, the first threshold value is set to a value lower than this.

[0025] Then, it is determined whether the number of storage battery modules 12 whose module temperatures are lower than the first threshold is equal to or less than the module control reference number (step S120). The module control reference number is set taking into consideration the fact that the storage battery modules 12 or storage battery cells 13 have a characteristic that the amount of power that can be input or output during low-temperature operation is reduced compared to normal-temperature operation due to an increase in internal resistance.

[0026] If the number of storage battery modules 12 whose module temperatures are below the first threshold is equal to or less than the module control reference number ("Yes" in step S120), the control determination unit 21 sets the control mode to the normal control mode, proceeds to step S200, and performs control to suppress variation in the heat generation amount of the storage battery modules 12.

[0027] On the other hand, if the number of storage battery modules 12 whose module temperatures are below the first threshold exceeds the module control reference number ("No" in step S120), the control determination unit 21 sets the control mode to low temperature control mode, proceeds to step S300, and performs low temperature control of the storage battery system 1.

[0028] <Normal Control Mode> The variation suppression control operation in the normal control mode will be described with reference to the flowchart in Figure 4. First, the control determination unit 21 calculates the heat generation amount of each of the multiple storage battery modules 12 and the average heat generation amount of all the modules (step S200). The heat generation amount of the storage battery module 12 is calculated by receiving measurement signals of the current value I and internal resistance R of each storage battery module 12 or storage battery cell 13 output from the BMS 15, for example, and calculating RI 2 Then, based on these calculation results, the average value of the calorific value is calculated.

[0029] Next, the control determination unit 21 outputs a control signal to the BMS 15 to decrease the amount of power input / output (power input / output amount) for the storage battery module 12 whose heat generation amount is higher than the average value, and outputs a control signal to the BMS 15 to increase the amount of power input / output for the storage battery module 12 whose heat generation amount is lower than the average value (step S210).

[0030] By implementing such control, it is possible to reduce the variation in the amount of heat generated among the multiple storage battery modules 12, i.e., the temperature variation, and to equalize the degree of deterioration of each of the multiple storage battery modules 12. Here, it is desirable that the decrease in the power input / output of a storage battery module 12 whose heat generation amount is higher than the average value and the increase in the power input / output of a storage battery module 12 whose heat generation amount is lower than the average value are equal when the amount of power input / output required to the storage battery system 1 via the power converter 93 is constant, and this control is used to minimize fluctuations in the amount of power input / output of the storage battery system 1.

[0031] Next, the control determination unit 21 recalculates the heat generation amount of each storage battery module 12 after adjusting the amount of power input / output in step S210 and the average value of all modules, and also calculates the difference between the heat generation amount of each storage battery module 12 and the average heat generation amount of all modules (step S220). As in step S200, the heat generation amount of each storage battery module 12 is calculated by receiving measurement signals of the current value I and internal resistance R of each storage battery module 12 or storage battery cell 13 output from the BMS 15, for example, and calculating RI 2 It can be calculated as:

[0032] Next, the control determination unit 21 determines whether the difference between the heat generation amount of each of the plurality of storage battery modules 12 and the average value obtained in step S220 is within a tolerance (step S230). In other words, the control determination unit 21 determines whether the temperature variation of the plurality of storage battery modules 12 is sufficiently suppressed as a result of performing the output adjustment control in step S210. It is desirable to set the tolerance for the difference between the heat generation amount of each of the plurality of storage battery modules 12 and the average value of the heat generation amount of all modules to a value as close to zero as possible in order to maximize the effect of this embodiment of suppressing deterioration variation among the plurality of storage battery modules 12.

[0033] If the difference between the heat generation amount of each of the plurality of storage battery modules 12 and the average heat generation amount of all the modules is not within the tolerance ("No" in step S230), the control determination unit 21 proceeds to step S210 again. On the other hand, if the difference between the heat generation amount of each of the plurality of storage battery modules 12 and the average heat generation amount of all the modules is within the tolerance ("Yes" in step S230), the control determination unit 21 receives a temperature measurement signal from the temperature measurement sensor 14 and measures the temperature of the power storage unit 10 or the storage battery module 12 (step S240).

[0034] Then, it is determined whether the measured temperature is higher than a second threshold value (step S250). If the standard operating temperature of the power storage unit 10 or the storage battery module 12 is 25°C, the second threshold value is set to a value higher than this.

[0035] If the measured temperature is higher than the second threshold value ('Yes' in step S250), the control determination unit 21 outputs a control determination signal to the EMS 94 to increase the amount of cooling output by the temperature adjustment device 22 to the storage unit 10 or multiple storage battery modules 12 (step S260).

[0036] At this time, even though cooling is not targeted at a specific storage battery module 12, the temperature variation among the multiple storage battery modules 12 can be reduced simply by adjusting the amount of power input and output in step S210. Therefore, the EMS 94 does not need to, for example, identify a storage battery module 12 (e.g., a specific module 12-H) that is hotter than the surrounding area and control the temperature adjustment device 22 to output an output that is tailored to the specific module 12-H. As a result, the storage battery system 1 of the present disclosure can achieve cooling of the storage battery system 1 or multiple storage battery modules 12 with simpler control than conventional methods.

[0037] After performing the above-described control in step S260, the control determination unit 21 proceeds to step S220 again. This is repeated until the measured temperature becomes equal to or less than the second threshold value ("No" in step S250). When the measured temperature becomes equal to or less than the second threshold value ("No" in step S250), the control determination unit 21 determines that the power storage unit 10 or the plurality of storage battery modules 12 is operating within an appropriate temperature range with temperature variation suppressed, and ends the control operation.

[0038] After the control operation is completed, the process may return to step S100 to continue the control determination sequence continuously, or may return to step S100 after an arbitrary interruption time has elapsed after one control determination sequence has been completed, and then the process may restart the control determination sequence. The arbitrary interruption time is set taking into consideration, for example, the operation frequency of the battery storage system 1, the power input / output conditions, etc.

[0039] <Low Temperature Control Mode> When a storage battery operates in a low temperature environment, its output decreases due to an increase in internal resistance, or its lifespan shortens due to deterioration. However, for example, Patent Document 1 does not take such a situation into consideration. Therefore, in the storage battery system 1 disclosed herein, when the number of modules whose module temperature is below the first threshold exceeds the module control reference number ("No" in step S120), the low temperature control mode is executed as a low temperature countermeasure. The operation of the low temperature control mode will be described with reference to the flowchart of FIG. 5.

[0040] In the battery storage system 1, if the number of modules at low temperatures (module temperature<first threshold) exceeds the module control reference number, it is determined that the power storage unit 10 cannot operate at the standard operating temperature and needs to be heated. This is because, when the determination in step S120 is "No," low-temperature control from step S300 onward is performed to operate the battery storage system 1 at the standard operating temperature and suppress deterioration due to low-temperature operation.

[0041] In the low-temperature control mode, the control determination unit 21 checks whether a power input / output control signal has been received from the EMS 94 via the power converter 93 to the power grid 91 or the load 92, that is, whether there is a power input / output request to the battery system 1 from outside the system (step S300). If the battery system 1 has received a power input / output control signal ("Yes" in step S300), this means that the battery system 1 must input / output power to the power grid 91 or the load 92 via the power converter 93 even in the low-temperature control mode.

[0042] In this case, the control determination unit 21 reduces the number of storage battery modules 12 operating below the standard operating temperature, and performs heating control to suppress deterioration of the storage battery modules 12 due to low-temperature operation. At the same time, the control flow proceeds to respond to a power input / output request from the power grid 91 or the load 92 via the power converter 93.

[0043] On the other hand, if the storage battery system 1 has not received the power input / output control signal ("No" in step S300), the storage battery system 1 does not need to input or output power to the power grid 91 or the load 92 via the power converter 93. In this case, the storage battery system 1 transitions to another low-temperature control mode called an internal input / output mode (step S400), which will be described in detail later.

[0044] In the normal low-temperature control mode (step S300: Yes), the control determination unit 21 determines whether any of the storage battery modules 12 has a module temperature equal to or higher than the first threshold value measured in step S100 of FIG. 3 (step S310). If at least one storage battery module 12 has a module temperature equal to or higher than the first threshold value (step S310: Yes), the control determination unit 21 selects a module whose module temperature is equal to or higher than the first threshold value (step S320). The control determination unit 21 then outputs a control determination signal to the EMS 94 to change the output direction of the temperature adjustment device 22 to the position of the selected module, thereby limiting the cooling target to the selected module (step S330).

[0045] By implementing the above-described control, in the battery storage system 1, even if the number of modules whose module temperatures are below the first threshold exceeds the module control reference number, the heat generated by the relatively high-temperature modules can be used to heat the low-temperature modules, which has the effect of eliminating the need for auxiliary equipment such as heaters that were previously required to heat the low-temperature modules and reducing the power consumption of auxiliary equipment such as heaters used for heating.

[0046] After performing the above-described control, the control determination unit 21 returns to step S100 shown in Fig. 3 to check whether the storage battery system 1 has been sufficiently heated. If the storage battery system 1 has not been sufficiently heated, the control determination unit 21 proceeds to the low-temperature control step again and repeats the same control. If the storage battery system 1 has been sufficiently heated, the control determination unit 21 returns to control that suppresses temperature variations using the normal control mode described in Fig. 4.

[0047] On the other hand, if there is no storage battery module 12 whose module temperature is equal to or higher than the first threshold in step S310 ("No" in step S310), the control determination unit 21 extracts modules whose module temperature is equal to or higher than a third threshold, which is lower than the first threshold. Furthermore, the control determination unit 21 calculates the difference between the module temperature of each of the multiple storage battery modules 12 and the third threshold (step S340). The third threshold is set to a temperature lower than the first threshold, at which module degradation will not occur even if input / output is increased. However, the average temperature of all modules may be used unless the temperature is extremely low.

[0048] Next, the control determination unit 21 performs at least one of the following (step S350): outputs a control signal to the BMS 15 to increase the amount of power input / output for modules whose module temperature is greater than or equal to the third threshold value, the greater the difference between the module temperature and the third threshold value, and decreases the amount of power input / output for modules whose module temperature is less than the third threshold value; and outputs a control determination signal to the EMS 94 to change the output direction of the temperature adjustment device 22 to the position of the module extracted in step S340, i.e., to limit the cooling target to the extracted module.

[0049] By performing the above-described control, the amount of power input / output of a module with a relatively high temperature (above the third threshold) among the plurality of storage battery modules 12 is increased to increase the amount of heat generated and attempt to return the module temperature to above the first threshold. Furthermore, storage batteries generally have a characteristic that the lower the operating temperature, the higher the internal resistance and the lower the amount of power that can be input / output. Therefore, by adjusting the amount of input / output according to temperature in the low-temperature control process, the amount of power that can be supplied / received from the power converter 93 can be increased compared to when the same amount of power is input / output to / from all of the plurality of storage battery modules 12 regardless of module temperature.

[0050] Therefore, similarly to steps S320 to S330, by using a module whose module temperature is equal to or higher than the third threshold as a heat source, it is possible to use it to heat a low-temperature module, which has the effect of eliminating the need for auxiliary equipment such as heaters that were previously required to heat low-temperature modules, and reducing the power consumption of auxiliary equipment such as heaters used for heating.

[0051] After performing the above-described control, the control determination unit 21 returns to step S100 shown in Fig. 3 to check whether the storage battery system 1 has been sufficiently heated. If the storage battery system 1 has not been sufficiently heated, the control determination unit 21 proceeds to the low-temperature control step again and repeats the same control. If the storage battery system 1 has been sufficiently heated, the control determination unit 21 returns to control that suppresses temperature variations using the normal control mode described in Fig. 4.

[0052] <Internal Input / Output Mode> If the storage battery system 1 has not received a power input / output control signal in step S300 ("No"), power input / output is not required between the storage battery system 1 and the power grid 91 or the load 92. The internal input / output mode, which is the operation in this case, will be described with reference to the flowchart in FIG.

[0053] Basically, in modes other than this internal input / output mode, power converter 93 performs power conversion to input / output power between load 92 or power grid 91 and power storage unit 10. However, even when converting from DC to AC, in order to convert power efficiently, the DC power is first boosted to a predetermined voltage and then converted into AC power. In other words, a converter circuit that converts DC power into desired power is formed within power converter 93.

[0054] 1 , the power converter 93 and the power storage unit 10 are connected via the system distributor 23, but in modes other than the internal input / output mode, all of the storage battery modules 12 are connected to the load 92 or the power system 91 by a main system Lm, which can be regarded as a simple power line for inputting and outputting power between the storage battery modules 12 and the load 92 or the power system 91. On the other hand, in the storage battery system 1 of the present disclosure, a sub-system Ls is provided that connects the storage battery modules 12 to the output terminal of the converter circuit in the power converter 93, and the connection of each module is allocated according to the situation.

[0055] In the internal input / output mode, the system distributor 23 has a function of distributing (switching) the systems so that a selected module of the power storage unit 10 is connected to the main system Lm and another selected module is connected to the sub system Ls. The operation will be described assuming this configuration.

[0056] If the control determination unit 21 determines that the storage battery system 1 has not received a control signal, that is, that there is no need for power input / output between the storage battery system 1 and the power grid 91 or the load 92, it transitions to internal input / output mode ('No' in step S300: Figure 5).

[0057] The control determination unit 21 first checks whether the SOC of each storage battery module 12 is within a predetermined range (e.g., higher than 0% and lower than 100%, indicating a state in which charging and discharging are possible) (step S400). If the SOC is within the range in which charging and discharging are possible ("Yes" in step S400), the control determination unit 21 determines whether there is at least one storage battery module 12 whose module temperature measured in step S100 ( FIG. 3 ) is equal to or higher than the first threshold value (step S410).

[0058] If there is at least one storage battery module 12 whose module temperature is equal to or higher than the first threshold ("Yes" in step S410), the control determination unit 21 extracts the storage battery module 12 whose module temperature is equal to or higher than the first threshold (step S420), selects the extracted storage battery module 12 as an output (discharge) target, and selects all the remaining modules or a selected module from among them as an input (charge) target (step S430).

[0059] The system controller 21 then commands the system divider 23 and the BMS 15 to connect the output target module to the main system Lm and the input target module to the sub-system Ls. The system controller 21 also commands the power converter 93 to boost the power input from the output target module to the power required to charge the input target module. In other words, power is exchanged between the selected modules via the boost converter (part of the power converter 93) (step S440). This allows power to be exchanged between the modules, and heating is performed using the heat generated by charging and discharging.

[0060] After completing input / output operations between modules via the boost converter, the BMS 15 may disconnect the storage battery module 12 from the boost converter. Furthermore, the system distributor 23 may disconnect the secondary system Ls and resume normal connection, connecting all modules to the main system Lm. At this time, there is a difference in power capacity between the storage battery modules 12, but due to the temperature rise, all modules are able to output. Therefore, input / output may be performed by swapping the input and output targets to cancel out the capacity difference. Heating can also be achieved using heat generated by the current circulating in a closed circuit in which multiple storage battery modules 12 are connected in parallel, i.e., by cross current.

[0061] Next, the control determination unit 21 outputs a control determination signal to the EMS 94 to change the output direction of the temperature adjustment device 22 to the position of the output target module, thereby limiting the cooling target to the output target module (step S480).

[0062] The control signal output by the control determination unit 21 to the BMS 15 to input and output power between modules includes information on the input and output modules and command values ​​for the amounts of power input and output. The absolute values ​​of the total amount of power input and output are set to be equal.

[0063] In the low-temperature control mode, the number of storage battery modules 12 whose module temperatures are equal to or higher than the first threshold is smaller than the module control reference number (step S120). Therefore, the number of output target modules is smaller than the total number of modules in the power storage unit 10, and the load of storage battery modules 12 with relatively high temperatures is preferentially increased.

[0064] The amount of power input to a storage battery module 12 whose module temperature is below the first threshold value only needs to correspond to the amount of power input / output to / from a storage battery module 12 whose module temperature is equal to or higher than the first threshold value, and some of the storage battery modules 12 whose temperature is below the first threshold value may be in a dormant state without receiving power input.

[0065] By implementing the above-described control, the battery system 1 can increase the heat generation amount by discharging the battery module 12, which has a relatively high temperature among the power storage units 10, and dissipate the heat as a heat source, thereby raising the temperature of the surrounding modules. Furthermore, by implementing the above-described control, when the battery system 1 is operating at a temperature lower than the standard temperature and the battery module 12 needs to be heated, auxiliary equipment such as a heater that was previously required becomes unnecessary, and power consumption of the auxiliary equipment such as a heater for heating can be reduced.

[0066] Furthermore, by selecting a storage battery module 12 with a relatively high temperature as an output target and a storage battery module 12 with a low temperature as an input target, power loss can be reduced compared to reverse selection or random selection. This is because, for example, assuming that the absolute values ​​of the increase in input voltage and the decrease in output voltage due to a temperature drop are the same, the ratio of power loss when the input voltage increases is smaller than when the output voltage decreases.

[0067] On the other hand, if there is no storage battery module 12 whose module temperature is equal to or higher than the first threshold ("No" in step S420), the control determination unit 21 extracts modules whose module temperature is equal to or higher than a third threshold that is lower than the first threshold, and further calculates the difference between the module temperature of each of the storage battery modules 12 and the third threshold (step S450).

[0068] Next, the control determination unit 21 selects the storage battery modules 12 whose module temperatures are equal to or higher than the third threshold as output (discharge) targets, and selects all of the remaining modules or selected modules from among them as input (charge) targets. Furthermore, for the output targets, the distribution amount is determined so that the output increases as the difference between the module temperature and the third threshold increases (step S460).

[0069] The system distributor 23 and the BMS 15 are then instructed to connect the output target module to the main system Lm and the input target module to the sub-system Ls. The system distributor 23 is also instructed to connect the power converter 93 to boost the power input from the output target module to the power required to charge the input target module. In particular, the system distributor 23 is instructed to adjust the output amount according to the distribution amount. In other words, weighted power input and output is realized between the selected modules via the boost converter (part of the power converter 93) (step S470). This allows power to be exchanged between the modules, and heating is performed using the heat generated by charging and discharging.

[0070] In this case, the temperature of the entire power storage unit 10 is lower than when there is a storage battery module 12 whose temperature is equal to or higher than the first threshold ("Yes" in step S410). Therefore, a third threshold is set to prevent input / output from being concentrated in only some storage battery modules 12, and a command value is determined so that the output of storage battery modules 12 whose temperatures are higher than the third threshold increases. Then, the control determination unit 21 outputs a control determination signal to the EMS 94 to change the output direction of the temperature adjustment device 22 to the position of the output target module, thereby limiting the cooling target to the output target module (step S480).

[0071] By implementing the above-described control, the battery system 1 can increase the heat generation amount by discharging the battery module 12, which has a relatively high temperature among the power storage units 10, and dissipate the heat as a heat source, thereby raising the temperature of the surrounding modules. Furthermore, by implementing the above-described control, when the battery system 1 is operating at a temperature lower than the standard temperature and the battery module 12 needs to be heated, auxiliary equipment such as a heater that was previously required becomes unnecessary, and power consumption of the auxiliary equipment such as a heater for heating can be reduced.

[0072] If the SOC of the battery module 12 is not within a predetermined range ("No" in step S400), the control determination unit 21 determines that the internal input / output described above cannot be realized. If the SOC is lower than the predetermined range, it determines that there is no remaining capacity for output, and selects the power grid 91 as the power source. On the other hand, if the SOC is higher than the predetermined range, a battery module 12 whose module temperature is equal to or higher than a first threshold is selected as the power source. If there is no battery module 12 whose module temperature is equal to or higher than the first threshold, the power grid 91 is selected as the power source (step S500). Then, the selected power source is connected to an auxiliary device such as a heater, and a control signal is output to heat the battery module 12 (step S510).

[0073] After performing the above-described control, the control determination unit 21 returns to step S100 shown in FIG. 3 to check whether the storage battery system 1 has been sufficiently heated. If the storage battery system 1 has not been sufficiently heated, the control determination unit 21 proceeds again to the low-temperature control step and repeats the same control. If the storage battery system 1 has been sufficiently heated, the control determination unit 21 returns to the control step of suppressing the temperature variation described above.

[0074] If the internal input / output mode is not used in the battery system 1, step S300 may be omitted and operation may begin from step S310 in the low-temperature control mode. In this case, the system distributor 23 and the sub-system Ls shown in FIG. 1 may also be omitted. While the present example illustrates an example in which a separate system distributor 23 is provided for internal input / output, this is not limiting. The BMS 15 of each of the multiple battery modules 12 may be provided with a function for switching between connection to the main system Lm and connection to the sub-system Ls, and may function as a system distributor.

[0075] In addition, although an example has been shown in which, if there is no power input / output request from outside the system ("Yes" in step S300), the system immediately transitions to the internal input / output mode to heat the power storage unit 10, the present invention is not limited to this. For example, if the start time of a power input / output request from outside the system is determined by a time setting function such as a scheduler or timer, the internal input / output mode may be started by waiting a predetermined time earlier than the start time.

[0076] In the first embodiment, the control for suppressing the temperature variation between modules based on the heat generation amount of each module in the normal control mode has been described. In the second embodiment, the control for suppressing the temperature variation between modules based on the heat generation parameter of each module will be described.

[0077] Fig. 7 is a flowchart for explaining the operation of the battery storage system according to the second embodiment, and is for explaining the operation of the normal control mode out of the two main control modes. Note that the configuration is the same as that of the first embodiment except for the use of a heat quantity parameter instead of the heat generation amount as an index for suppressing temperature variation, and Figs. 1 to 3, 5, and 6 used in the first embodiment are also used.

[0078] The configuration of the storage battery system 1 according to the second embodiment will be described below in terms of differences from the first embodiment. In the second embodiment, each of the plurality of storage battery modules 12 constituting the storage battery system 1 is provided at an arbitrary position with a temperature measurement sensor 14 that measures the module temperature and the environmental temperature (ambient temperature) around the storage battery module 12 and outputs a temperature measurement signal to the control determination unit 21. A plurality of temperature measurement sensors 14 may be provided for each module to measure the respective temperatures.

[0079] The control method of the control determination unit 21 in the battery temperature control system of the second embodiment will be described with reference to the flowchart of Fig. 7. As described in the first embodiment, when the number of modules whose module temperatures are below the first threshold in Fig. 3 is equal to or less than the module control reference number ("Yes" in step S120), the control determination unit 21 transitions to a normal control mode in which temperature variation suppression control of the storage battery modules 12 is performed.

[0080] At this time, in the storage battery system 1 according to the second embodiment, the control determination unit 21 calculates the heat quantity parameter of each of the plurality of storage battery modules 12 and the average value thereof (step S200V).

[0081] The heat quantity parameter of each storage battery module 12 is, for example, RI described in the first embodiment. 2 The heat dissipation amount of the storage battery module 12 is expressed as the difference between the heat generation amount of the storage battery module 12 calculated as follows: and the heat dissipation amount of the storage battery module 12. In calculating the heat dissipation amount of the storage battery module 12, for example, the surface temperature of the storage battery module 12 or the storage battery cell 13 is Ts (K), the ambient temperature around the storage battery module 12 or the storage battery cell 13 is Ta (K), and the surface area of ​​the storage battery module 12 or the storage battery cell 13 is S (m 2 ) far away.

[0082] And, εσ(Ts 4 -Ta 4)S, or the amount of heat loss due to convection calculated by h(Ts-Ta)S, or the sum of these. Here, ε represents the emissivity determined by the surface material of the storage battery module 12 or storage battery cell 13, and σ represents the Stefan-Boltzmann constant, both of which are input as constants to the memory 213 of the control determination unit 21. h represents the heat transfer coefficient (W / mK) and is calculated using the convection wind speed (m / s).

[0083] Next, the control determination unit 21 outputs a control signal to the BMS 15 to decrease the amount of power input / output for the storage battery module 12 whose heat quantity parameter is higher than the average value, and outputs a control signal to the BMS 15 to increase the amount of power input / output for the storage battery module 12 whose heat quantity parameter is lower than the average value (step S210V).

[0084] By implementing such control, it is possible to reduce the variation in the heat quantity parameter, i.e., the temperature variation, occurring among the plurality of storage battery modules 12, and to equalize the degree of deterioration of each of the plurality of storage battery modules 12. Here, it is desirable that the amount of decrease in power input / output of a storage battery module 12 whose heat quantity parameter is higher than the average value and the amount of increase in power input / output of a storage battery module 12 whose heat quantity parameter is lower than the average value are equal when the amount of power input / output required to the storage battery system 1 via the power converter 93 is constant, and this control is used to minimize fluctuations in the amount of power input / output of the storage battery system 1.

[0085] Next, the control determination unit 21 recalculates the heat quantity parameter of each storage battery module 12 after adjusting the amount of power input / output in step S210V and the average value of all modules, and also calculates the difference between the heat quantity parameter of each of the multiple storage battery modules 12 and the average value of all modules (step S220V). The heat quantity parameter of each storage battery module 12 is calculated in the same way as in step S200V.

[0086] Next, the control determination unit 21 determines, for each of the plurality of storage battery modules 12, whether the difference between the heat quantity parameter for each module obtained in step S220V and the average value of the heat quantity parameters falls within a tolerance (step S230V). That is, the control determination unit 21 determines whether the temperature variation of the plurality of storage battery modules 12 is sufficiently suppressed as a result of performing the output adjustment control in step S210V. It is desirable to set the tolerance for the difference between the heat quantity parameter of each of the plurality of storage battery modules 12 and the average value of the heat quantity parameters of all modules to a value as close to zero as possible in order to maximize the effect of this embodiment of suppressing deterioration variation among the plurality of storage battery modules 12.

[0087] If the difference between the heat generation amount of each of the plurality of storage battery modules 12 and the average value of the heat parameter of all the modules is not within the allowable value ("No" in step S230V), the control determination unit 21 proceeds to step S210V again. On the other hand, if the difference between each heat parameter and the average value of the heat parameter of all the modules is within the allowable value ("Yes" in step S230V), the control determination unit 21 receives a temperature measurement signal from the temperature measurement sensor 14 and measures the temperature of the power storage unit 10 or the storage battery module 12 (step S240).

[0088] Thereafter, it is determined whether the measured temperature is higher than the second threshold value (step S250), as in the first embodiment. If the measured temperature is higher than the second threshold value ("Yes" in step S250), the control determination unit 21 outputs a control determination signal to the EMS 94 to increase the amount of cooling output by the temperature adjustment device 22 to the power storage unit 10 or the plurality of storage battery modules 12 (step S260).

[0089] At this time, even though cooling is not targeted at a specific storage battery module 12, the temperature variation among the multiple storage battery modules 12 can be reduced simply by adjusting the amount of power input and output in step S210V. Therefore, the EMS 94 does not need to perform control such as, for example, targeting output to a specific module 12-H that is hotter than its surroundings. As a result, the storage battery system 1 of the present disclosure can achieve cooling of the storage battery system 1 or multiple storage battery modules 12 with simpler control than conventional methods.

[0090] After performing the above-described control in step S260, the control determination unit 21 proceeds to step S220V again. This is repeated until the measured temperature becomes equal to or less than the second threshold value ("No" in step S250). When the measured temperature becomes equal to or less than the second threshold value ("No" in step S250), the control determination unit 21 determines that the power storage unit 10 or the plurality of storage battery modules 12 is operating within an appropriate temperature range with temperature variation suppressed, and ends the control operation.

[0091] After the control operation is completed, the process may return to step S100 to continue the control determination sequence continuously, or may return to step S100 after an arbitrary interruption time has elapsed after one control determination sequence has been completed, and then the process may restart the control determination sequence. The arbitrary interruption time is set taking into consideration, for example, the operation frequency of the battery storage system 1, the power input / output conditions, etc.

[0092] In the storage battery system 1 of the present disclosure, controllers such as the control determination unit 21, the BMS 15, and the temperature adjustment device 22 that perform control operations can be configured with a processor 300 and a storage device 301, as shown in FIG. 8 , which is an example of hardware 30. Although not shown, the storage device may include a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. Alternatively, a hard disk auxiliary storage device may be used instead of the flash memory. The processor 300 executes a program input from the storage device 301. In this case, the program is input from the auxiliary storage device to the processor 300 via the volatile storage device. The processor 300 may output data such as calculation results to the volatile storage device of the storage device 301, or may store the data in the auxiliary storage device via the volatile storage device. The processor 300 may have a communication function, or may include a communication unit (not shown).

[0093] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, and even cases where at least one component is extracted and combined with components of another embodiment.

[0094] As described above, the storage battery system 1 of the present disclosure includes the power storage unit 10 having the plurality of storage battery modules 12, each of which is configured with a plurality of storage battery cells 13 and connected in parallel with one another, the input / output control unit (BMS 15) that controls the input / output amount of each of the plurality of storage battery modules 12 and measures the internal resistance, and the distribution adjustment unit (control determination unit 21) that controls the input / output control unit (BMS 15) to adjust the distribution of the input / output amount to each of the plurality of storage battery modules 12 based on the heat generation amount of each of the plurality of storage battery modules 12 calculated from the internal resistance of each of the plurality of storage battery modules 12, in relation to the input / output amount of power required for the power storage unit 10. This makes it possible to suppress the spread of temperature distribution between the modules and extend the life of the system.

[0095] In particular, the distribution adjustment unit (control determination unit 21) adjusts the distribution so as to reduce the variation in the heat generation amount calculated for each of the multiple storage battery modules 12, thereby homogenizing the heat generation between the modules and further suppressing the spread of the temperature distribution.

[0096] The system also includes a temperature sensor 14 that measures the temperature of each of the multiple storage battery modules 12, and a temperature adjustment device 22 that provides cooling output to the multiple storage battery modules 12 to adjust the temperature, and when the variation in heat generation is below a set value and the temperature of the storage unit 10 is higher than an upper limit temperature, the distribution adjustment unit (control determination unit 21) controls the temperature adjustment device 22 to adjust at least one of the magnitude of the cooling output and the distribution of the cooling output to each of the multiple storage battery modules 12 so that the temperature of the storage unit 10 is below the upper limit temperature.This makes it possible to compensate for variations in heat generation and equalize the temperature.

[0097] Alternatively, a temperature sensor 14 may be provided to measure the temperature of each of the plurality of storage battery modules 12, and the distribution adjustment unit (control determination unit 21) may adjust the distribution so as to reduce the variation in the heat parameter of each of the plurality of storage battery modules calculated from the difference between the amount of heat dissipation and the amount of heat generation calculated from the difference between the temperature of each of the plurality of storage battery modules 12 and the ambient temperature. This makes it possible to homogenize the heat parameter between the modules and further suppress the spread of the temperature distribution.

[0098] In this case, a temperature adjustment device 22 is provided that provides cooling output to the multiple storage battery modules 12 to adjust the temperature, and if the variation in the heat quantity parameter is below a set value and the temperature of the storage unit 10 is higher than an upper limit temperature, the distribution adjustment unit (control determination unit 21) controls the temperature adjustment device 22 to adjust at least one of the magnitude of the cooling output and the distribution of the cooling output to each of the multiple storage battery modules 12 so that the temperature of the storage unit 10 is below the upper limit temperature.This makes it possible to compensate for variation in the heat quantity parameter and make the temperature uniform.

[0099] The plurality of storage battery modules 12 each have a temperature sensor 13 for measuring the temperature thereof. Between each of the plurality of storage battery modules 12 and the power converter 93, in addition to a main system Lm for inputting and outputting power to and from an external load 92 or a power source (power system 91) via the power converter 93, a sub-system Lm for receiving an output from a converter circuit that boosts DC power input from the main system Lm of the power converter 93 to a predetermined voltage, and a system distributor 23 (or BMS 15) for distributing the connection destination of each of the plurality of storage battery modules 12 to either the main system Lm or the sub-system Ls are provided. The system distributor 23 When input / output of the above is not required and the number of modules among the multiple storage battery modules 12 whose temperature is lower than the lower limit temperature (first threshold) exceeds the control reference number (module control reference number), a storage battery module 12 with a relatively higher temperature among the multiple storage battery modules 12 is selected as the output target module, and one of the remaining storage battery modules 12 is selected as the input target module. If the system is configured to allocate the output target module so that it is connected to the main system Lm and the input target module is connected to the sub-system Ls, the temperature can be raised efficiently through internal power input / output.

[0100] 1: Battery system, 10: Power storage unit, 11: Battery rack, 12: Battery module, 13: Battery cell, 14: Temperature measurement sensor, 15: BMS (input / output control unit), 20: Control unit, 21: Control determination unit (distribution adjustment unit), 211: Signal processing unit, 212: Communication unit, 213: Memory, 22: Temperature adjustment device (temperature adjustment unit), 23: System distributor, 91: Power system, 92: Load, 93: Power converter, 94: EMS (distribution adjustment unit).

Claims

1. A storage battery system comprising: a power storage unit having a plurality of storage battery modules, each of which is composed of a plurality of storage battery cells and connected in parallel with each other; an input / output control unit that controls the input / output amount of each of the plurality of storage battery modules and measures their internal resistance; and a distribution adjustment unit that controls the input / output control unit based on the amount of heat generated by each of the plurality of storage battery modules calculated from the internal resistance of each of the plurality of storage battery modules in relation to the input / output amount of power required for the power storage unit, and adjusts the distribution of the input / output amount to each of the plurality of storage battery modules.

2. The storage battery system according to claim 1, characterized in that the distribution adjustment unit adjusts the distribution so as to reduce the variation in the heat generation amount calculated for each of the multiple storage battery modules.

3. A storage battery system as described in claim 2, further comprising: a temperature sensor that measures the temperature of each of the plurality of storage battery modules; and a temperature adjustment unit that provides cooling output to the plurality of storage battery modules for temperature adjustment, wherein when the variation in the amount of heat generated is below a set value and the temperature of the storage unit is higher than an upper limit temperature, the distribution adjustment unit controls the temperature adjustment unit to adjust at least one of the magnitude of the cooling output and the distribution of the cooling output to each of the plurality of storage battery modules so that the temperature of the storage unit is below the upper limit temperature.

4. The storage battery system of claim 1, further comprising a temperature sensor for measuring the temperature of each of the plurality of storage battery modules, and the distribution adjustment unit adjusts the distribution so as to reduce variation in the heat parameter of each of the plurality of storage battery modules calculated from the difference between the amount of heat dissipation and the amount of heat generated, the difference being calculated from the difference between the temperature of each of the plurality of storage battery modules and the ambient temperature.

5. The battery system according to claim 4, further comprising a temperature adjustment unit that provides cooling output for temperature adjustment to the plurality of battery modules, wherein the distribution adjustment unit controls the temperature adjustment unit to adjust at least one of the magnitude of the cooling output and the distribution of the cooling output to each of the plurality of battery modules so that the temperature of the battery unit is equal to or lower than the upper limit temperature when the variation in the heat parameter is equal to or lower than a set value and the temperature of the battery unit is higher than an upper limit temperature.

6. The storage battery system according to any one of claims 1 to 5, further comprising a temperature sensor for measuring the temperature of each of the plurality of storage battery modules, and between each of the plurality of storage battery modules and the power converter, in addition to a main system for inputting and outputting power to and from an external load or power source via the power converter, a sub-system for receiving an output from a converter circuit that boosts DC power input from the main system of the power converter to a predetermined voltage, and a system distributor for distributing the connection destinations of each of the plurality of storage battery modules to one of the main system and the sub-system, wherein, when the input / output of power is not required and the number of modules among the plurality of storage battery modules that have a temperature lower than a lower limit temperature exceeds a control reference number, the system distributor selects a storage battery module among the plurality of storage battery modules that has a relatively high temperature as an output target module and selects one of the remaining storage battery modules as an input target module, and distributes the systems so that the output target module is connected to the main system and the input target module is connected to the sub-system.

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