Energy storage control device, energy storage device, method for calculating remaining charging time, and program for calculating remaining charging time

Abstract

To improve the estimation accuracy of the remaining charging time.SOLUTION: A power storage control device includes a processing unit that calculates the remaining charging time of a power storage device that supplies power to a load device that operates by supplying power from an external power supply in an emergency when the external power supply is in a power supply state. The processing unit calculates the remaining charging time of the power storage device on the basis of a linearly approximated correlation between the usage environment of the power storage device and the charging time including a charging interruption time of the power storage device.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This disclosure relates to an energy storage control device, an energy storage device, a method for calculating remaining charging time, and a program for calculating remaining charging time. [Background technology]

[0002] A battery storage device (also called a "battery bank unit") has been known for discharging power to load devices that operate on power supplied from an external power source, primarily in the event of an emergency (e.g., a power outage) where the external power supply is unavailable (see, for example, Patent Document 1). A battery storage device generally has multiple battery storage devices (also called a "battery bank" or "battery pack"), each of which is composed of multiple secondary batteries that can be charged by power supplied from an external power source during normal operation, and which are connected in parallel to each other.

[0003] Multiple energy storage devices can each have their discharge capabilities controlled by switching their corresponding output switches on or off. To prevent one of the energy storage devices from discharging for charging, its corresponding output switch is turned off. Simultaneously, to enable other energy storage devices to discharge for power supply, their corresponding output switches are turned on. This type of charging method is sometimes called a "bank switching method." The bank switching method allows for uninterrupted power supply to load devices when needed, and prevents unnecessary power supply to load devices when not required.

[0004] By the way, for example, for the purpose of managing load devices, there is a need to know the time required to charge an energy storage device, and especially the remaining time required for charging (remaining charging time) when it is currently charging.

[0005] One method for calculating the remaining charging time to estimate the remaining charging time is described in Patent Document 2, for example. The conventional method for calculating the remaining charging time described in Patent Document 2 obtains an estimated value of the remaining charging time from the SOC (State of Charge) obtained by integrating the charging current and the charging current during charging. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-10250 [Patent Document 2] Japanese Patent Application Publication No. 9-322420 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in energy storage devices, there may be periods of charging interruption during which the built-in energy storage devices are not temporarily charged. For example, in energy storage devices that employ the bank switching method described above, there may be a period during which neither energy storage device is temporarily charged after one energy storage device has finished charging and before the other energy storage device begins charging.

[0008] The conventional method for calculating remaining charge time described above does not account for periods of charging interruption. Therefore, there are certain limitations to improving the accuracy of the remaining charge time estimation.

[0009] This disclosure aims to provide a power storage control device, a power storage device, a method for calculating remaining charging time, and a program for calculating remaining charging time that can improve the accuracy of estimating remaining charging time. [Means for solving the problem]

[0010] One embodiment of the energy storage control device relating to this disclosure is: The charging method employs a bank switching system. remaining charge of the energy storage device interval It has a processing unit that performs calculations. In an energy storage control device, The aforementioned processing unit, From among the multiple correlation data stored in the memory unit that correspond to the battery temperature of the energy storage device, a specific correlation data corresponding to the battery temperature at the start of charging is selected. Using the selected correlation data, an estimated value of the full charge time corresponding to the input voltage at the start of charging is calculated based on a linearly approximated correlation between the input voltage from the external power supply and the full charge time including the charging interruption time of the energy storage device. The estimated full charging time is adjusted based on the charging state of the energy storage device at the start of charging to calculate the remaining charging time. Furthermore, after charging is complete, the measured value, which is the result of measuring the charging time from the start of charging to full charge, is normalized to a value equivalent to the full charging time based on the charging state at the start of charging, and the converted value of the full charging time is obtained. The reference value for the full charging time corresponding to the battery temperature at the start of charging is updated based on the acquired converted value of the full charging time. The reference value of the input voltage corresponding to the battery temperature at the start of charging is updated based on the input voltage at the start of charging.

[0011] One aspect of the power storage device according to the present disclosure is a power storage device that supplies power to a load device that operates by power supply from an external power source in an emergency of the power supply state of the external power source, and has the above-described power storage control device.

[0012] One aspect of the remaining charge time calculation method according to the present disclosure is by a processing unit, The charging method employs a bank switching system. the remaining charge time of the power storage device Calculate is output In the method for calculating remaining charging time , The aforementioned processing unit, From among the multiple correlation data stored in the memory unit that correspond to the battery temperature of the energy storage device, a specific correlation data corresponding to the battery temperature at the start of charging is selected. Using the selected correlation data, an estimated value of the full charge time corresponding to the input voltage at the start of charging is calculated based on a linearly approximated correlation between the input voltage from the external power supply and the full charge time including the charging interruption time of the energy storage device. The estimated full charging time is adjusted based on the charging state of the energy storage device at the start of charging to calculate the remaining charging time. Furthermore, after charging is complete, the measured value, which is the result of measuring the charging time required from the start of charging to full charge, is normalized to a value equivalent to the full charging time based on the charging state at the start of charging, and a converted value of the full charging time is obtained. The reference value for the full charging time corresponding to the battery temperature at the start of charging is updated based on the acquired converted value of the full charging time. The reference value of the input voltage corresponding to the battery temperature at the start of charging is updated based on the input voltage at the start of charging.

[0013] One aspect of the remaining charge time calculation program according to the present disclosure is to cause a computer to realize the above-described remaining charge time calculation method.

Effects of the Invention

[0014] According to the present disclosure, the estimation accuracy of the remaining charge time can be improved.

Brief Description of the Drawings

[0015] [Figure 1] A diagram schematically showing the configuration of a battery bank unit according to an embodiment of the present disclosure [Figure 2] A block diagram showing the configuration of the control device shown in FIG. 1 [Figure 3] A diagram showing an example of a table stored in the storage unit shown in FIG. 2 [Figure 4] A flowchart showing the charging process of the battery bank unit according to the present embodiment [Figure 5]Time chart showing the charging process of the battery bank unit according to this embodiment [Figure 6] Flowchart showing the method for calculating the remaining charge time of the battery bank unit according to this embodiment. [Figure 7A] A diagram illustrating the correlation between input voltage and charging time. [Figure 7B] A diagram illustrating the correlation between SOC and charging time. [Modes for carrying out the invention]

[0016] Hereinafter, a battery bank unit (BBU) according to one embodiment of the present disclosure will be described with reference to the drawings.

[0017] Figure 1 is a schematic diagram of the BBU1 according to this embodiment. The BBU1 supplies power to the load device 3 connected to the external power supply 2 when the external power supply 2 fails. The BBU1 is also charged by the power from the external power supply 2.

[0018] External power supply 2 is a device that converts commercial AC power to DC power and outputs it, for example. Load device 3 is a device that operates on DC power (for example, a server device).

[0019] BBU1 has input / output terminals 10, a control device 20, a power storage unit 30, and a charge / discharge circuit 40. BBU1 is an example of a power storage device.

[0020] The input / output terminal 10 is connected to a power line 4 that supplies power from an external power supply 2 to the load device 3. By connecting the input / output terminal 10 to the power line 4, the BBU1 can supply power to the load device 3 in the event of an emergency (mainly a power outage) in the power supply state of the external power supply 2.

[0021] The energy storage unit 30 includes a first battery bank (BB) 31 and a second BB 32. The first BB 31 and the second BB 32 are each examples of energy storage devices, and they are configured similarly to each other. For example, the first BB 31 and the second BB 32 each have a configuration in which multiple secondary batteries are connected in series. In this embodiment, the type of secondary battery is a nickel-metal hydride secondary battery. However, the type of secondary battery may be a lithium-ion secondary battery or other secondary battery besides a nickel-metal hydride secondary battery. The first BB 31 and the second BB 32 are connected in parallel to each other.

[0022] The charge / discharge circuit 40 functions as a circuit that charges and discharges the first BB31 and the second BB32 via the input / output terminals 10. The charge / discharge circuit 40 includes a boost DC / DC converter 41, a changeover switch 42, a first charge switch 43, a first discharge switch 44, a second charge switch 45, a second discharge switch 46, a first constant current circuit 48, and a second constant current circuit 49. In the charging process described later, the charge / discharge circuit 40 sequentially (or alternately) charges the first BB31 and the second BB32. In other words, BBU1 employs a bank switching method as its charging method.

[0023] The boost DC / DC converter 41 is a power conversion device that boosts the power supplied from the external power supply 2 and outputs it.

[0024] The changeover switch 42 switches the voltage values ​​applied to the first BB31 and the second BB32. In the changeover switch 42, the first terminal 42a is connected to the output terminal of the boost DC / DC converter 41, and the second terminal 42b is connected to the input / output terminal 10. The third terminal 42c is connected to the first BB31 via the first charging switch 43 and the first constant current circuit 48, and to the second BB32 via the second charging switch 45 and the second constant current circuit 49.

[0025] When the changeover switch 42 is in the ON position, the first terminal 42a and the third terminal 42c are connected. In this case, the power output from the external power supply is output via the boost DC / DC converter 41. That is, the power output from the boost DC / DC converter 41 is supplied to the first BB31 and the second BB32 via the first charging switch 43 and the second charging switch 45. On the other hand, when the changeover switch 42 is in the OFF position, the second terminal 42b and the third terminal 42c are connected, and the power output from the external power supply 2 is supplied to the first BB31 and the second BB32 via the first charging switch 43 and the second charging switch 45 without going through the boost DC / DC converter 41.

[0026] The first charging switch 43 allows charging of the first BB31 when it is in the ON state, and does not allow charging of the first BB31 when it is in the OFF state. In the first charging switch 43, the first terminal 43a is connected to the third terminal 42c of the changeover switch 42, and the second terminal 43b is connected to the positive terminal of the first BB31. The negative terminal of the first BB31 is connected to ground.

[0027] The first discharge switch 44 allows discharge of the first BB31 when it is in the ON state, and does not allow discharge of the first BB31 when it is in the OFF state. In the first discharge switch 44, the first terminal 44a is connected to the positive terminal of the first BB31, and the second terminal 44b is connected to the input / output terminal 10.

[0028] The second charging switch 45 allows charging of the second BB32 when it is in the ON state, and does not allow charging of the second BB32 when it is in the OFF state. In the second charging switch 45, the first terminal 45a is connected to the third terminal 42c of the changeover switch 42, and the second terminal 45b is connected to the positive terminal of the second BB32. The negative terminal of the second BB32 is connected to ground.

[0029] The second discharge switch 46 allows discharge of the second BB32 when it is in the ON state, and does not allow discharge of the second BB32 when it is in the OFF state. In the second discharge switch 46, the first terminal 46a is connected to the positive terminal of the second BB32, and the second terminal 46b is connected to the input / output terminal 10.

[0030] Figure 2 is a block diagram of BBU1. As shown in Figure 2, BBU1 further includes an input / output voltage sensor 61, an input / output current sensor 62, a first battery voltage sensor 63, a first battery temperature sensor 64, a second battery voltage sensor 65, and a second battery temperature sensor 66.

[0031] The input / output voltage sensor 61 detects the voltage value that is input from the external power supply 2 to the BBU 1 via the input / output terminal 10, or output from the BBU 1 to the load device 3 via the input / output terminal 10. Specifically, the input / output voltage sensor 61 detects the voltage value between the input / output terminal 10 and the connection point 40a of the charge / discharge circuit 40. Based on the input voltage value (power supply voltage value) from the external power supply 2 to the BBU 1 detected by the input / output voltage sensor 61, a power outage of the external power supply 2 can be detected.

[0032] The input / output current sensor 62 detects the current value flowing into or out of the power line 4 via the input / output terminal 10. Specifically, the input / output current sensor 62 detects the current value between the input / output terminal 10 and the connection point 40a of the charge / discharge circuit 40.

[0033] The first battery voltage sensor 63 detects the voltage value of the first battery battery 31. The first battery temperature sensor 64 detects the temperature of the first battery battery 31.

[0034] The second battery voltage sensor 65 detects the voltage value of the second battery battery 32. The second battery temperature sensor 66 detects the temperature of the second battery battery 32. The input / output voltage sensor 61, input / output current sensor 62, first battery voltage sensor 63, first battery temperature sensor 64, second battery voltage sensor 65, and second battery temperature sensor 66 each transmit their detected values ​​to the control device 20.

[0035] The first constant current circuit 48 and the second constant current circuit 49 are provided corresponding to the first BB31 and the second BB32, respectively. The first constant current circuit 48 and the second constant current circuit 49 output a constant current to the corresponding first BB31 and second BB32, regardless of the voltage input from the external power supply 2 (either via or without the boost DC / DC converter 41).

[0036] The first constant current circuit 48 and the second constant current circuit 49 may be provided in accordance with the respective secondary batteries when a type of secondary battery for which constant current charging is desirable is used, such as the nickel-metal hydride secondary battery used in this embodiment.

[0037] The control device 20 has a storage unit 21 and a processing unit 22, and is implemented by, for example, a computer. The processing unit 22 is implemented by, for example, a CPU (Central Processing Unit). The storage unit 21 includes a storage device implemented by, for example, an HDD (Hard Disk Drive) and a memory device implemented by, for example, RAM (Random Access Memory).

[0038] The processing unit 22 reads various control programs or instructions for realizing each function of the BBU1, and data etc. related to said programs or instructions (hereinafter also simply referred to as "programs etc.") from the storage device and stores them in the memory device, and executes various control programs or instructions using the data etc. In this embodiment, the data etc. includes table T and mathematical formulas, which will be described later.

[0039] The program and other data may be stored in a removable storage medium such as flash memory. In this case, the control device 20 is configured to allow the removable storage medium to be attached and detached, and reads the program and other data from the storage medium. Alternatively, the control device 20 may be configured to communicate with the outside world so that the program and other data can be downloaded to the control device 20 from the outside via a communication network.

[0040] The storage devices, memory devices, and removable storage media described above are examples of non-temporary storage media.

[0041] The control device 20 controls the state of each of the switches 42 to 46. The control device 20 also controls the drive of the boost DC / DC converter 41. By controlling each part of the BBU1 with the control device 20, the charging and discharging of the BBU1 is controlled, and the BBU1 functions as, for example, an uninterruptible power supply. The control device 20 is an example of an energy storage control device that controls the BBU1, which is an energy storage device.

[0042] Table T is a set of data referenced by the control device 20 when calculating the remaining charge time. The calculation of the remaining charge time is performed when charging of BBU1 begins. The remaining charge time is the time required from the start of charging of BBU1 until charging is complete.

[0043] Figure 3 shows an example of table T. In table T, the battery temperature, the reference value for full charge time (reference value for full charge time FTR), and the reference value for input voltage (reference value for input voltage VR) are associated with each other for each reference value for battery temperature (in this embodiment, temperature range).

[0044] Table T is an example of correlation data showing the correlation between the operating environment of BBU1 and the charging time of BBU1. The combination of the full charging time reference value FTR and the input voltage reference value VR is an example of battery temperature-specific data set for each battery temperature reference value of BBU1. In this embodiment, "operating environment" includes, for example, the battery temperature at the start of charging, the input voltage at the start of charging, and the SOC at the start of charging.

[0045] In Table T, the battery temperature is divided into a total of six temperature zones. Within the typical operating temperature range of nickel-metal hydride rechargeable batteries, from 0°C to 40°C, the temperature is divided into six zones of 10°C each. It goes without saying that the number of temperature zones is not limited to the example shown in Figure 3.

[0046] In the example shown in Figure 3, for example, for a battery temperature of "below 0°C," "A0" is stored as the full charge time reference value FTR and "B0" as the input voltage reference value. "A0," "A1," "A2," "A3," "A4," and "A5" as full charge time reference values ​​FTR, and "B0," "B1," "B2," "B3," "B4," and "B5" as input voltage reference values ​​are all shown as symbols for convenience, but are actually numerical values, and these values ​​may be updated after charging is complete. The usage of Table T (method for calculating remaining charging time) will be described later.

[0047] The configuration of the BBU1 according to this embodiment has been described above.

[0048] Next, an example of the charging process of the BBU1 performed by the control device 20 will be explained using the flowchart in Figure 4 and the time chart in Figure 5.

[0049] In the graph shown in the upper part of Figure 5, the solid line voltage value represents the voltage value of the first BB31, and the dashed line voltage value represents the voltage value of the second BB32. In this example, the voltage values ​​of the first BB31 and the second BB32 are assumed to be approximately equal before the start of the batch charging process and during the batch charging process. In other words, the lines representing the voltage values ​​of the first BB31 and the second BB32 overlap and are therefore shown as solid lines. Also, the "power supply voltage value" shown in Figure 5 is the voltage value that is normally input from the external power supply 2 to the load device 3 and BBU1. Therefore, in the following explanation, unless otherwise specified, the power supply voltage value is the normal power supply voltage value. Needless to say, in emergencies such as power outages, the actual power supply voltage value of the external power supply 2 will be significantly lower than the normal power supply voltage value.

[0050] When the charging process has not started, the changeover switch 42, the first charging switch 43, and the second charging switch 45 are all in the OFF state, and the first discharge switch 44 and the second discharge switch 46 are all in the ON state. This allows the discharge of the first BB31 and the second BB32. In this example, the voltage values ​​and charge amounts of the first BB31 and the second BB32 are assumed to be approximately equal before the charging process starts. Therefore, the SOC of BBU1, which is the average of the SOC of the first BB31 and the SOC of the second BB32, is approximately equal to the SOC of the first BB31 and the second BB32, respectively. Incidentally, the SOC of the first BB31 and the second BB32 can be calculated, for example, from the measured values ​​of their respective battery voltages.

[0051] The control device 20 starts the charging process when it detects a connection to the external power supply 2 based on the input / output voltage sensor 61, or when it detects the end of a power outage at the external power supply 2. The control device 20 may also start the charging process when the SOC of the BBU 1 drops below a predetermined value.

[0052] In step S101, the control device 20 starts the batch charging process. The batch charging process is a process of charging the first BB31 and the second BB32 at the same time. Specifically, as shown in Figure 5, the control device 20 switches the changeover switch 42, the first charging switch 43, and the second charging switch 45 to the ON state from a state in which the changeover switch 42, the first charging switch 43, and the second charging switch 45 are all OFF, and the first discharge switch 44 and the second discharge switch 46 are all ON (time t0).

[0053] The first discharge switch 44 and the second discharge switch remain in the ON state. As a result, even if the external power supply 2 experiences a power outage during the batch charging process, if the battery voltage value of at least one of the first BB31 and the second BB32 exceeds the power supply voltage value of the external power supply 2 (during a power outage), discharge will occur and power can be supplied from the BBU1 to the load device 3.

[0054] When the batch charging process begins (time t0), power is supplied from the boost DC / DC converter 41 to the first BB31 and the second BB32, and the voltage values ​​of the first BB31 and the second BB32 increase.

[0055] Next, in step S102, the control device 20 determines whether the bank voltage value, which is the voltage value of BBU1, is equal to or greater than the power supply voltage value. Specifically, the bank voltage value is the average value of the voltage value of the first BB31 and the voltage value of the second BB32. Note that the bank voltage value may be the voltage value of either the first BB31 or the second BB32. If the bank voltage value is lower than the power supply voltage value (NO in S102), the batch charging process continues.

[0056] On the other hand, if the voltage values ​​of the first BB31 and the second BB32 rise and the bank voltage value becomes equal to or greater than the power supply voltage value (YES at time t1; S102), the control device 20 terminates the batch charging process in step S103 and starts the first bank charging process.

[0057] The first bank charging process is a process that charges only the first BB31. During the first bank charging process, the first BB31 is charged to a fully charged state. The battery voltage value in the fully charged state is a voltage value that is sufficiently higher than the power supply voltage value. The second BB32 is not charged during the first bank charging process.

[0058] Specifically, the control device 20 switches the second charging switch 45 to the off state and also switches the first discharge switch 44 to the off state (time t1). As a result, power from the boost DC / DC converter 41 is supplied only to the first BB31, and the voltage value of the first BB32 rises further than the power supply voltage value. During the first bank charging process, the first discharge switch 44 is in the off state, and the first BB31 is not discharged. Therefore, it is possible to prevent a voltage higher than the power supply voltage value from being applied to the load device 3, and consequently, to prevent failure of the load device 3.

[0059] Meanwhile, charging of the second BB32 is stopped, and the voltage value of the second BB32 gradually decreases due to self-discharge. During the first bank charging process, the second discharge switch 46 is in the ON state. Therefore, if the external power supply 2 experiences a power outage during the first bank charging process and the power supply voltage value drops significantly below the normal power supply voltage value, the discharge of the second BB32 will begin, and power will be supplied from the BBU1 to the load device 3.

[0060] Next, in step S104, the control device 20 determines whether the first BB31 has reached a fully charged state. Specifically, the control device 20 determines whether the value detected by the first battery temperature sensor 64 has reached a predetermined first temperature. The first temperature is the temperature at which the first BB31 reaches a fully charged state. If the value detected by the first battery temperature sensor 64 is lower than the first temperature (NO in S104), the control device 20 continues the first bank charging process, which charges only the first BB31.

[0061] On the other hand, when the first BB31 is fully charged and the value detected by the first battery temperature sensor 64 reaches the first temperature (time t2; YES at S104), the control device 20 stops the first bank charging process, which charges only the first BB31, in step S105.

[0062] Specifically, the control device 20 switches the first charging switch 43 to the off state (time t2). As a result, charging of the first BB31 stops, and the voltage value of the first BB31 gradually decreases due to self-discharge. At this time, the temperature of the first BB31 is higher than the temperature of the second BB32. Therefore, the rate of voltage drop per unit time of the first BB31 is greater than the rate of voltage drop per unit time of the second BB32.

[0063] Next, in step S106, the control device 20 determines whether the voltage value of the first BB31 has become less than or equal to the power supply voltage value. If the voltage value of the first BB31 is higher than the power supply voltage value (NO in S106), the control device 20 continues to keep the charging of both the first BB31 and the second BB32 stopped. This period (from time t2 to time t3) is the charging interruption period.

[0064] On the other hand, if the voltage value of the first BB31 falls below the power supply voltage value (YES at time t3; S106), the control device 20 terminates the first bank charging process and starts the second bank charging process in step S107.

[0065] The second bank charging process is a process that charges only the second BB32. During the second bank charging process, the second BB32 is charged to a fully charged state. The first BB31 is not charged during the second bank charging process.

[0066] Specifically, the control device 20 switches the second charging switch 45 to the ON state, the first discharge switch 44 to the ON state, and the second discharge switch 46 to the OFF state (time t3). As a result, power is supplied from the boost DC / DC converter 41 only to the second BB32, the voltage value of the second BB32 rises and eventually exceeds the power supply voltage value. During the second bank charging process, the second discharge switch 46 is in the OFF state, and the second BB32 is not discharged. Therefore, it is possible to prevent a voltage value higher than the power supply voltage value from being applied to the load device 3, and consequently, to prevent failure of the load device 3.

[0067] Meanwhile, charging of the first BB31 remains stopped, and the voltage value of the first BB31 gradually decreases due to self-discharge. During the second bank charging process, the first discharge switch 44 is in the ON state. Therefore, if the external power supply 2 experiences a power outage during the second bank charging process and the power supply voltage value drops significantly below the normal power supply voltage value, the discharge of the first BB31 will begin, and power will be supplied from the BBU1 to the load device 3.

[0068] Next, in step S108, the control device 20 determines whether the second BB32 has reached a fully charged state. Specifically, the control device 20 determines whether the value detected by the second battery temperature sensor 66 has reached a predetermined second temperature. The second temperature is the temperature at which the second BB32 reaches a fully charged state. The second temperature may be the same as the first temperature. If the value detected by the second battery temperature sensor 66 is lower than the second temperature (NO in S108), the control device 20 continues the second bank charging process, which charges only the second BB32.

[0069] On the other hand, when the second BB32 is fully charged and the value detected by the second battery temperature sensor 66 reaches the second temperature (time t4; YES at S108), the control device 20 stops the second bank charging process, which charges only the second BB32, in step S109.

[0070] Specifically, the control device 20 switches the second charging switch 45 to the off state (time t4). As a result, charging of the second BB32 stops, and the voltage value of the second BB32 gradually decreases due to self-discharge. At this time, the temperature of the second BB32 is higher than the temperature of the first BB31. Therefore, the rate of voltage drop per unit time of the second BB32 is greater than the rate of voltage drop per unit time of the first BB31.

[0071] Next, in step S110, the control device 20 determines whether the voltage value of the second BB32 has become less than or equal to the power supply voltage value. If the voltage value of the second BB32 is higher than the power supply voltage value (NO in S110), the control device 20 continues the state in which charging of the first BB31 and the second BB32 is stopped.

[0072] On the other hand, if the voltage value of the second BB32 falls below the power supply voltage value (time t5; YES in S110), the control device 20 terminates the second bank charging process in step S111. Specifically, the control device 20 switches the changeover switch 42 to the OFF state and the second discharge switch 46 to the ON state (time t5). This terminates the charging of BBU1 and ends the series of charging processes. The control device 20 sets the SOC of BBU1 at the time the charging of BBU1 is terminated to 100%.

[0073] Note that BBU1 may have three or more battery banks. If there are N battery banks (where N is an integer greater than or equal to 3), the batch charging process charges all N battery banks at once. After the batch charging process is completed, the nth bank charging process (where n is an integer from 1 to N) is executed sequentially for each of the N battery banks, similar to the first and second bank charging processes described above. If there are many battery banks, the N battery banks may be divided into M battery bank groups (where M is an integer greater than or equal to 2), and the mth bank charging process (where m is an integer from 1 to M) may be executed sequentially for each of the M battery bank groups. In the mth bank charging process, multiple battery banks belonging to the same battery bank group are charged simultaneously.

[0074] Next, the method for calculating the remaining charge time of the BBU1, which is executed by the processing unit 22 of the control device 20, will be explained using the flowchart in Figure 6.

[0075] When the charging process begins (step S201), the processing unit 22 acquires the battery temperature, input voltage, and SOC at the start of charging (step S202). The conditions for starting the charging process include, as described above, the connection of BBU1 to the external power supply 2, the end of a power outage of the external power supply 2, or a decrease in the SOC of BBU1. The processing unit 22 calculates the battery temperature at the start of charging by taking the average value of the detection value of the first battery temperature sensor 64 and the detection value of the second battery temperature sensor 66, which are acquired at the start of the charging process. The processing unit 22 also acquires the detection value of the input / output voltage sensor 61 as the input voltage at the start of charging (input voltage VM at the start of charging). The processing unit 22 also acquires the SOC at the start of charging (hereinafter referred to as "charging state at the start of charging SOCS") from the detection value of the first battery voltage sensor 63 and the detection value of the second battery voltage sensor 65, which are acquired at the start of the charging process, as well as a predetermined voltage value corresponding to 100% SOC of BBU1.

[0076] Then, the processing unit 22 refers to table T (step S203). At this time, the processing unit 22 reads out the input voltage (input voltage reference value VR) and full charging time (full charging time reference value FTR) from table T that correspond to the temperature range to which the battery temperature at the start of charging is located.

[0077] Then, the processing unit 22 performs a charging time estimation process (step S204). Specifically, the processing unit 22 calculates an estimated full charging time and then calculates an estimated remaining charging time.

[0078] The estimated full charging time is calculated using the following equation (1). Equation (1) is pre-stored in the memory unit 21.

number

[0079] In equation (1), k is a constant. The specific numerical values ​​of equation (1) and the constant k are stored in the storage unit 21 beforehand. The constant k is an example of correlation data.

[0080] In equation (1), the full charge time estimate FTE can be obtained by adjusting the full charge time reference value FTR with a value obtained by multiplying the difference between the input voltage VM at the start of charging and the input voltage reference value VR by a constant k.

[0081] The remaining charging time is calculated using the following formula (2).

number

[0082] In equation (2), k temp k is a constant set for each temperature zone divided in table T. Equation (2) and constant k temp The specific numerical value is stored in the memory unit 21 beforehand. Constant k temp This is an example of correlation data.

[0083] In equation (2), the estimated full charge time FTE calculated in equation (1) is used, and the charge state SOCS at the start of charging is used as a constant k. temp By adjusting the value obtained by multiplying by the constant k, the estimated remaining charging time RTE can be obtained. temp The value multiplied by is the estimated length of time by which the charging time is shortened depending on the initial charge state SOCS; in other words, it is the estimated length of time required to charge the SOC from 0% to the initial charge state SOCS.

[0084] The calculated estimated remaining charging time (RTE) can be used as appropriate, for example, by displaying it on the display unit (not shown) of the administrator terminal of the load device 3 or BBU1.

[0085] Here, constant k and constant k temp This will be explained with reference to Figures 7A and 7B. Figure 7A shows the correlation between the input voltage at the start of charging and the charging time, and Figure 7B shows the correlation between the state of charge (SOC) at the start of charging and the charging time.

[0086] Figure 7A is a graph plotting data collected from experiments conducted beforehand using BBU1 or a BBU with the same configuration as BBU1, before BBU1 was connected to the power line 4. The graph in Figure 7A plots the measurement results of full charging time at different input voltages (power supply voltage values) measured multiple times under different battery temperatures. Since the measurement results were obtained using a bank-switching type BBU, the full charging time includes not only the time when any BB is being charged, but also the charging interruption time when no BB is being charged.

[0087] The graph in Figure 7A shows the approximate lines ALa25 and ALa35, which linearly approximate the correlation between measurement results at the same battery temperature. That is, it can be seen that there is a correlation between input voltage and full charge time that can be approximated by a line. As shown in Figure 7A, according to these experimental results, the slope (constant of the first-order approximation formula) of these lines ALa25 and ALa35 is constant regardless of the battery temperature. Therefore, the correlation between input voltage and full charge time does not depend on the battery temperature. Accordingly, assuming that there are known combinations of input voltages and corresponding known full charge times, when determining a new full charge time from a new input voltage, the known full charge time should be adjusted based on a value obtained by multiplying the difference between these two input voltages by a constant k that does not depend on the battery temperature. The reason for using the above formula (1) when calculating the full charge time estimate FTE is as described above.

[0088] Figure 7B is a graph plotting data collected from experiments conducted beforehand using BBU1 or a BBU with the same configuration as BBU1, before BBU1 is connected to the power line 4. The graph in Figure 7B plots the measurement results of the required charging time from different initial states of charge (SOC) to a fully charged state, measured multiple times under different battery temperatures. Since the measurement results are from a bank-switching type BBU, the required charging time includes not only the time when any BB is being charged, but also the charging interruption time when no BB is being charged.

[0089] The graph in Figure 7B shows the approximate lines ALb25 and ALb35, which linearly approximate the correlation between measurement results at the same battery temperature. That is, it can be seen that there is a linearly approximated correlation between the initial state of charge (SOC) and the required charging time. As shown in Figure 7B, according to these experimental results, the slopes (constants in the linear approximation equation) of these lines ALb25 and ALb35 differ depending on the battery temperature. Therefore, the correlation between the initial SOC and the required charging time depends on the battery temperature. Consequently, assuming that an estimated full charging time exists for a specific battery temperature, when determining the new required charging time (i.e., remaining charging time) from a new initial SOC, the constant k corresponding to that specific battery temperature is used for this new initial SOC. temp The existing full-charge time estimate should be adjusted based on the value obtained by multiplying by . The reason for using equation (2) above when calculating the remaining charge time estimate RTE is as described above.

[0090] In step S205, the processing unit 22 waits until the charging process is completed (NO in S205). When the charging process is completed (YES in S205), the processing unit 22 obtains the measured value of the charging time (measured charging time TM) (step S206). The measured charging time TM can be obtained, for example, by the processing unit 22 using a timer (not shown) in the control device 20 to measure the elapsed time from the start of charging to the completion of charging. Needless to say, if a charging interruption occurs during the charging process, the charging interruption time will be included in this measured charging time TM.

[0091] The processing unit 22 normalizes the acquired measured charging time TM (step S207). Specifically, the processing unit 22 converts the measured charging time TM to obtain an estimated full charging time (full charging time conversion value FTC).

[0092] The FTC (Full Charging Time) is calculated using the following formula (3).

number

[0093] In equation (3) above, the FTC (Full Charge Time) can be calculated by adding the measured charging time TM to the estimated length of time required to charge the SOC from 0% to the initial charging state SOCS.

[0094] This full charge time equivalent (FTC) includes the most recent measured charging time (TM) as one component. Furthermore, if there is a charging interruption during the charging process, that interruption time is included in the measured charging time (TM). Therefore, the full charge time equivalent (FTC) is more accurate than the full charge time estimate (FTE) obtained using the above formula (1) as an estimate of the time required for a full charge (charging from 0% to 100%) in the current usage environment.

[0095] The processing unit 22 updates the full charge time reference value FTR and the input voltage reference value VR in table T using the full charge time conversion value FTC calculated in step S207 and the input voltage TM at the start of charging acquired in step S201 (step S208). For example, if the battery temperature at the start of charging is 15°C, then the full charge time reference value FTR "A2" and input voltage reference value VR "B2" in table T, which are associated with a battery temperature of "10°C or more and less than 20°C", will be updated. The updated full charge time reference value FTR and input voltage reference value VR will be used in subsequent calculations of the remaining charge time. In subsequent calculations of the remaining charge time, correlation data learned according to the most recent usage environment will be used, enabling more accurate estimation of the remaining charge time.

[0096] As described above, according to this embodiment, in the control device 20, the processing unit 22 that calculates the remaining charge time of BBU1 calculates the remaining charge time of BBU1 based on a linearly approximated correlation between the operating environment of BBU1 and the charging time that includes the charging interruption time of BBU1. This makes it possible to estimate the remaining charge time taking into account the charging interruption time that occurs in, for example, the bank switching method, thereby improving the accuracy of the remaining charge time estimation.

[0097] In addition, the processing unit 22 reads out the correlation data stored in advance in the storage unit 21, calculates the remaining charge time using the read correlation data, and updates the correlation data in the storage unit 21 based on the measured value of the charging time. As a result, the correlation data learned according to the most recent usage environment of the BBU1 can be used for estimating the remaining charge time after the next time, so that the estimation accuracy can be continuously improved. By repeatedly performing the estimation, the estimation error can be minimized.

[0098] In addition, the processing unit 22 calculates the remaining charge time using specific battery temperature-specific data corresponding to the battery temperature at the start of charging among the battery temperature-specific data set for each reference value of the battery temperature of the BBU1. As a result, different correlation data according to the battery temperature can be reflected in the calculation of the remaining charge time, so that highly accurate estimation of the remaining charge time can be performed for any battery temperature.

[0099] In addition, the battery temperature-specific data includes a full charge time reference value FTR and an input voltage reference value VR. The processing unit 22 adjusts the full charge time reference value FTR based on the difference between the input voltage VM at the start of charging and the input voltage reference value VR to obtain a full charge time estimated value FTE, and adjusts the obtained full charge time estimated value FTE based on the state of charge SOCS at the start of charging to obtain a remaining charge time estimated value RTE. As a result, highly accurate estimation of the remaining charge time can be performed based on the known full charge time reference value FTR and input voltage reference value VR.

[0100] In addition, the correlation data includes constants k and k of an approximate expression representing the correlation. temp The processing unit 22 uses a constant k independent of the battery temperature for adjusting the full charge time reference value FTR, and uses a constant k temp dependent on the battery temperature for adjusting the full charge time estimated value FTE. As a result, the correlation between the input voltage independent of the battery temperature and the full charge time (see FIG. 7A), and the correlation between the SOC at the start of charging dependent on the battery temperature and the required charging time (see FIG. 7B) can be reflected in the calculation of the remaining charge time, so that highly accurate estimation of the remaining charge time can be more reliably performed.

[0101] Furthermore, the processing unit 22 converts the measured charging time TM to obtain a full charging time equivalent value FTC, updates the full charging time reference value FTR corresponding to the battery temperature at the start of charging based on the obtained full charging time equivalent value FTC, and updates the input voltage reference value VR corresponding to the battery temperature at the start of charging based on the input voltage VM at the start of charging. By normalizing the measured charging time TM to a value that is easy to use for subsequent estimations (full charging time equivalent value FTC), the correlation data can be easily updated.

[0102] Although embodiments of this disclosure have been specifically described above, this disclosure is not limited to the specific embodiments described above. Various modifications and changes are possible to the specific examples described above within the scope of the gist of this disclosure as stated in the claims.

[0103] For example, a separate energy storage control device may be placed outside the BBU1, and the control device 20 inside the BBU1 and the energy storage control device outside the BBU1 may communicate with each other to execute the remaining charge time calculation method described in the above embodiment at the external energy storage control device. [Industrial applicability]

[0104] This disclosure can be suitably used as a control device for a power storage device that supplies power to a load device that operates on power supplied from an external power source in the event of an emergency in the power supply state of the external power source. [Explanation of Symbols]

[0105] 1 Battery Bank Unit 2 External power supply 3 Load device 4 Power lines 10 Input / output terminals 20 Control device 21 Memory section 22 Processing Units 30 Energy storage unit 31. Battery Bank No. 1 32. Second Battery Bank 40 Charge / discharge circuit 41. Boost DC / DC Converter 42 Changeover switch 42a Terminal 1 42b 2nd terminal 42c Third terminal 43. First charging switch 43a Terminal 1 43b 2nd terminal 44. First discharge switch 44a Terminal 1 44b Second terminal 45. Second charging switch 45a First terminal 45b Second terminal 46. ​​Second discharge switch 46a Terminal 1 46b Second terminal 48 1st constant current circuit 49 2nd constant current circuit 61 Input / Output Voltage Sensor 62 Input / Output Current Sensor 63. First battery voltage sensor 64. First battery temperature sensor 65. Second battery voltage sensor 66. Second battery temperature sensor T Table ALa25, ALa35, ALb25, ALb35 Approximate straight line

Claims

1. A power storage control device having a processing unit for calculating the remaining charging time of a power storage device that employs a bank switching method as a charging method, The aforementioned processing unit, From among the multiple correlation data stored in the memory unit that correspond to the battery temperature of the energy storage device, a specific correlation data corresponding to the battery temperature at the start of charging is selected. Using the selected correlation data, an estimated value of the full charge time corresponding to the input voltage at the start of charging is calculated based on a linearly approximated correlation between the input voltage from the external power supply and the full charge time including the charging interruption time of the energy storage device. The estimated full charging time is adjusted based on the charging state of the energy storage device at the start of charging to calculate the remaining charging time. Furthermore, after charging is complete, the measured value, which is the result of measuring the charging time from the start of charging to full charge, is normalized to a value equivalent to the full charging time based on the charging state at the start of charging, and the converted value of the full charging time is obtained. The reference value for the full charging time corresponding to the battery temperature at the start of charging is updated based on the acquired converted value of the full charging time. The reference value of the input voltage corresponding to the battery temperature at the start of charging is updated based on the input voltage at the start of charging. Energy storage control device.

2. The correlation data includes constants in the approximation formula representing the correlation, The processing unit uses a constant independent of the battery temperature to adjust the reference value of the full charging time, and uses a constant dependent on the battery temperature to adjust the estimated value of the full charging time. The energy storage control device according to claim 1.

3. A power storage device that supplies power to a load device that operates using power supplied from an external power source in the event of an emergency in the power supply state of the external power source, Having the energy storage control device described in claim 1, Energy storage device.

4. In a method for calculating the remaining charge time of an energy storage device that employs a bank switching method as its charging method, the processing unit calculates the remaining charge time of the energy storage device. The aforementioned processing unit, From among the multiple correlation data stored in the memory unit that correspond to the battery temperature of the energy storage device, a specific correlation data corresponding to the battery temperature at the start of charging is selected. Using the selected correlation data, an estimated value of the full charge time corresponding to the input voltage at the start of charging is calculated based on a linearly approximated correlation between the input voltage from the external power supply and the full charge time including the charging interruption time of the energy storage device. The estimated full charging time is adjusted based on the charging state of the energy storage device at the start of charging to calculate the remaining charging time. Furthermore, after charging is complete, the measured value, which is the result of measuring the charging time from the start of charging to full charge, is normalized to a value equivalent to the full charging time based on the charging state at the start of charging, and the converted value of the full charging time is obtained. The reference value for the full charging time corresponding to the battery temperature at the start of charging is updated based on the acquired converted value of the full charging time. The reference value of the input voltage corresponding to the battery temperature at the start of charging is updated based on the input voltage at the start of charging. How to calculate remaining charging time.

5. A program for calculating remaining charging time, which causes a computer to execute the charging time calculation method described in claim 4.

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