Battery management system, battery management method, and program

Abstract

This invention provides a battery management system, a battery management method, and a program that enable accurate estimation of remaining battery charge. [Solution] In the battery device 100, the battery management system 110 includes a charge control unit 112 that controls the charging of the secondary battery 102, a voltage sensor 121 that detects the voltage of the secondary battery 102, and a control unit 113 that estimates which of a plurality of ranges the remaining charge of the secondary battery is in as an estimated range. The control unit 113 determines a provisional range that provisionally indicates which of the plurality of ranges the remaining charge is in based on the voltage detected in each of the plurality of charging conditions of the charge control unit 112, and estimates the current estimated range based on a comparison of the provisional range and past estimated ranges.

Description

Technical Field

[0006] , , ,

[0005] , ,

[0001] The present invention relates to a battery management system, a battery management method, and a program.

Background Art

[0002] Patent Document 1 describes a vacuum cleaner that notifies a user of information on the remaining charge of a secondary battery by a light emission mode. Generally, the voltage of a secondary battery fluctuates as the remaining charge increases or decreases. Furthermore, even when the remaining charge is the same, the voltage of the secondary battery fluctuates when the charging status switches, such as from charging to non-charging or vice versa.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The remaining charge of a secondary battery has a correlation with the voltage, and the remaining charge can be mainly expressed as a function of the voltage. On the other hand, the above function is different when the charging status of the secondary battery is charging and when it is non-charging. Therefore, the remaining charge of the secondary battery can be estimated based on the information on the charging status and the voltage. However, when the charging status switches, there may be a delay until the control unit can identify the switch. During the delay period, since the estimation result of the charging status is different from the actual charging status, an error is given to the estimation result of the remaining charge.

[0005] An object of the present invention is to provide a battery management system, a battery management method, and a program capable of more accurately estimating the remaining charge.

Means for Solving the Problems

[0006] A battery management system according to one aspect of the present invention is A charge control unit that controls the charging of a secondary battery, A voltage sensor for detecting the voltage of the secondary battery, A control unit that estimates which of a plurality of ranges the remaining charge of the secondary battery is within, and sets that range as the estimated range. Equipped with, The control unit, Based on the detected voltage in each of the multiple charging conditions of the charging control unit, a provisional range is determined that provisionally indicates which of the multiple ranges the remaining charge falls into. The current estimated range is estimated based on a comparison of the aforementioned provisional range with the previously estimated range. [Effects of the Invention]

[0007] According to the present invention, the effect is obtained that accurate estimation of the remaining charge can be obtained. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing an electrical device incorporating the battery management system of this embodiment. [Figure 2] This is the first part of a flowchart showing the procedure for the remaining quantity estimation process performed by the control unit. [Figure 3] This is the second part of the flowchart. [Figure 4] This is the third part of the flowchart. [Figure 5] This diagram illustrates an example of the behavior when the charging status switches from charging to not charging. [Figure 6] This diagram illustrates an example of the behavior when the charging status switches from not charging to charging. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in Figure 1, the battery management system 110 of this embodiment is incorporated into an electrical device 100. The electrical device 100 includes a secondary battery 102 and a functional unit 101 that operates using the power of the secondary battery 102. The electrical device 100 is not particularly limited, but a wide variety of devices can be applied, such as a sensor device that detects a predetermined physical quantity, household electrical appliances, or a robot. The functional unit 101 corresponds to an electronic or electrical device that performs some or all of the functions of the electrical device 100.

[0010] The battery management system 110 includes a charger 111 that takes power from an external power source and supplies charging power to the secondary battery 102, a charging control unit 112 that controls the charging of the secondary battery 102 via the charger 111, a control unit 113 that estimates the remaining charge of the secondary battery 102, and a communication unit 114 that communicates with the communication terminal 200 at least regarding the remaining charge. Furthermore, the battery management system 110 includes a voltage sensor 121 that detects the voltage of the secondary battery 102 and a temperature sensor 122 that detects the temperature of the secondary battery 102. The remaining charge corresponds to, for example, SOC (State of Charge). The communication unit 114 corresponds to an example of a transmission unit that sends out information regarding the estimated remaining charge to the outside.

[0011] The secondary battery 102 is, for example, a lithium-ion secondary battery, but various other secondary batteries such as lithium polymer secondary batteries and nickel-metal hydride secondary batteries may be used. The charger 111 is configured to take in power non-contact (specifically, a method in which there is no contact between power lines) via electromagnetic action, but it may also be configured to take in power via a wire. The charger 111 charges the secondary battery 102 using a constant current constant voltage method, but various other charging methods may be used. When power is supplied from the secondary battery 102 to the functional unit 101 etc. in a non-charging state, a voltage drop occurs due to the internal resistance of the secondary battery 102. On the other hand, during charging, power is supplied from an external power source to the functional unit 101 etc., and no discharge current is generated from the secondary battery 102, so the above voltage drop does not occur. Therefore, the voltage of the secondary battery 102 appears higher during charging than when it is not charging.

[0012] The voltage sensor 121 sends its detected value to at least the charge control unit 112 and the control unit 113. The temperature sensor 122 sends its detected value to at least the charge control unit 112.

[0013] The charging control unit 112 controls the charging status of the secondary battery 102. The charging status includes "charging" where the secondary battery 102 is being charged by the charger 111, "charging complete" where charging has stopped because the secondary battery 102 is fully charged, "charging error" where charging has stopped due to an error, and "not charging" where charging is not taking place due to factors other than full charge or error. Specifically, "charging error" refers to situations where charging does not start even though the battery is in a state where it can be charged, or where the temperature of the secondary battery 102 is abnormally high, or any other abnormality that prevents charging. The charging control unit 112 switches the charging status to "not charging" when the connection to the external power supply is lost while in the "charging" state. The charging control unit 112 switches the charging status to "not charging" when the power of the secondary battery 102 is consumed and the remaining charge decreases by a predetermined amount from the "charging complete" state. The charging control unit 112 stops the charging operation of the charger 111 when it is in the "not charging" state.

[0014] "Fully charged" in the context of "charging complete" more specifically refers to the point when the voltage of the secondary battery 102 reaches the full charge voltage, or when the charging is switched to constant current charging after reaching the full charge voltage and the charging current falls below a predetermined value. The full charge voltage is set to a value that protects the secondary battery 102 from overcharging. When the secondary battery 102 is within the standard temperature range, the standard full charge voltage (e.g., 4V) is applied. On the other hand, when the secondary battery 102 is in the caution temperature range, which is outside the standard temperature range, a different high-temperature full charge voltage (e.g., 3.9V) is applied. The charging control unit 112 switches the charging status to "charging complete" when charging is completed at the standard full charge voltage if the battery is within the standard temperature range. On the other hand, when the battery is within the caution temperature range, the charging control unit 112 switches the charging status to "charging complete" when charging is completed at the high-temperature full charge voltage.

[0015] The charge control unit 112 identifies the charging status of the secondary battery 102 based on the detection signal of the voltage sensor 121, the detection signal of the temperature sensor 122, the status information of the charger 111 (connection information with the non-contact power transmitter, input voltage information, etc.), and the like. The charge control unit 112 notifies the user of the identified charging status, for example, by the light emission state of the light emitting unit. Further, the charge control unit 112 sends charging status information indicating the charging status to the control unit 113. The charging status information may be a signal or the like generated for the purpose of notifying the control unit 113 of the charging status, but may also be information or a signal generated for other purposes. For example, the charging status information may be used in combination with a signal for controlling the light emission state of the above-mentioned light emitting unit. That is, the charging status may be represented by the light emission state, and a signal corresponding to the light emission state may be sent to the control unit 113 as the charging status information. Note that the above light emission may be replaced by the output of other notification media such as voice output, vibration, and notification to the mobile terminal. If the time required for the charging status information to represent one charging status is long, there will be a delay in identifying the charging status from the charging status information for that time.

[0016] The control unit 113 is a controller that operates by executing a control program stored in the storage unit 113a. The controller may be called a microcomputer or a computer. The control program includes a program 113b for remaining amount estimation processing. The control unit 113 may be configured to read and execute the program 113b for remaining amount estimation processing stored in a portable storage medium.

[0017] In the remaining charge estimation process, the control unit 113 estimates the remaining charge of the secondary battery 102 based on the voltage of the secondary battery 102 and the charging status information. The control unit 113 may be configured to perform the remaining charge estimation process irregularly based on an external request from the battery management system 110 and return the estimated charge amount. Specifically, the external request may be a request from a communication terminal 200 having a display unit 201, a communication unit 203, and a terminal control unit 202, such as a mobile phone. The communication unit 114 can communicate with the communication unit 203 of the terminal control unit 202, for example, via wireless communication. The display unit 201 of the communication terminal 200 may be configured to display and output the remaining charge amount. The terminal control unit 202 requests information on the remaining charge amount from the control unit 113 irregularly or at repeating timings that include variations. For example, the communication terminal 200 may periodically make a request only when the output of the display unit 201 transitions to the battery level display screen, or, if other priority processing is being performed on the communication terminal 200, it may make a request when there is free time between priority processing. More specifically, a configuration may be adopted in which the above request is made at a predetermined interval of seconds, minutes, or hours, or at the timing when a predetermined interval of variation is added during that period. The minimum interval for the above request is shorter than the delay ΔT described later. The control unit 113 estimates the battery level based on the request and sends the battery level information to the terminal control unit 202. The terminal control unit 202 updates the battery level display based on the battery level information.

[0018] The control unit 113 stores in advance in the storage unit 113a a first table 113c and a second table 113d that show the relationship between the voltage of the secondary battery 102 and the remaining charge amount. The first table 113c is a data table showing the relationship between the voltage and the remaining charge amount when not charging. The second table 113d is a data table showing the relationship between the voltage and the remaining charge amount during charging. In the first table 113c and the second table 113d, the remaining charge amount may be represented by discrete values indicating in which of a plurality of ranges the remaining charge amount is. In the present embodiment, an example is shown in which three ranges are applied as the plurality of ranges of the remaining charge amount: a "first level" of less than 33%, a "second level" of 33% or more and less than 67%, and a "third level" of 67% or more. However, different ranges such as four or more ranges may be adopted for the above plurality of ranges.

[0019] The voltage values in the first table 113c and the second table 113d show voltage values in a plurality of ranges respectively corresponding to the above plurality of ranges of the remaining charge amount. When the secondary battery 102 has the same remaining charge amount, the voltage is higher during charging than when not charging. During charging, the output voltage of the charger 111 matches the voltage of the secondary battery 102. Therefore, when comparing the voltage range corresponding to the third level (for example, 3.75V or more) in the first table 113c with the voltage range corresponding to the first level (for example, 3.9V or more) in the second table 113d, they may have a partial overlap, but the latter is higher. The same applies to the voltage ranges corresponding to the second level (for example, less than 3.75V and 3.65V or more, less than 3.9V and 3.85V or more, etc.) and the voltage ranges corresponding to the third level (for example, less than 3.65V, less than 3.85V, etc.).

[0020] The control unit 113 uses the first table 113c and the second table 113d to provisionally determine which of several ranges the remaining charge of the secondary battery 102 falls within. Hereinafter, the provisionally determined range will be referred to as the "provisional range." Furthermore, the control unit 113 finally estimates which of several ranges the remaining charge of the secondary battery 102 falls within. Hereinafter, the estimated range will be referred to as the "estimated range." The provisional range and the estimated range are any of the above-mentioned ranges (specifically, the first to third levels). The display unit 201 may display the remaining charge using a graphic 201a. The graphic 201a may be a graphic indicating which of the above-mentioned ranges the remaining charge falls within.

[0021] The control unit 113 repeatedly executes the remaining charge estimation process shown in Figures 2 to 4 based on an external request (specifically, a request from the communication terminal 200). The external request may also be a request from a higher-level control unit. In each of the repeatedly executed remaining charge estimation processes, the currently executed process is referred to as "this time," and the previously executed process is referred to as "last time." In Figures 2 to 4, "cur0_lv" indicates a provisional range (one of the first to third levels) that shows the range of the remaining charge provisionally estimated in the current process, or the variable that stores it. "cur_lv" indicates the estimated range (one of the first to third levels) that is the estimation result of the current process, or the variable that stores it. "pre_lv" indicates the estimated range (one of the first to third levels) that is the estimation result of the previous process, or mainly the variable that stores it. "clip_cnt" is a variable that stores the number of consecutive clipping processes, which will be described later. "pre_time" is a variable that stores the time when the previous estimation range was determined (or the time when the previous estimation range was sent to the communication terminal 200). "cur_vol" indicates the voltage of the secondary battery 102 obtained in the current remaining charge estimation process, or the variable that stores it. More specifically, "cur_vol" stores the average value of the voltage measured over the most recent predetermined time period (e.g., 1 second). The remaining charge estimation process in Figures 2 to 4 corresponds to an example of a battery management method that manages the charging and remaining charge of the secondary battery 102. The remaining charge estimation program 113b causes the control unit 113, which is a computer, to function as a means for estimating the remaining charge.

[0022] As shown in Figure 2, when the control unit 113 receives a request for information on the remaining charge of the secondary battery 102 from the communication terminal 200, it starts a single remaining charge estimation process. When the process starts, the control unit 113 first estimates the charge status of the secondary battery 102 based on the charge status information from the charge control unit 112 (step S1). If there is a change in the charge status, there is a delay between the actual change and the time when the change can be identified. Therefore, when there is a change in the charge status, the charge status estimated in step S1 may be the charge status before the change. Specifically, "when ~" means "a period of several seconds (for example, 1 second to 5 seconds) after ~ occurs".

[0023] Next, the control unit 113 determines whether the charging status estimated in step S1 has changed from the previous time to the current time, or whether a threshold time (e.g., 5 seconds) or more has elapsed since pre_time, or whether clip_cnt has exceeded a threshold number of times (e.g., 5 times) (step S2). If any of these is YES, the control unit 113 proceeds to step S3; if all are NO, the control unit 113 proceeds to step S5.

[0024] As a result, if the process proceeds to step S3, the control unit 113 performs a reset process to disable the clipping process (the process of setting the previous estimated range as the current estimated range), which will be described later. Specifically, the control unit 113 writes an invalid value to pre_lv as part of the reset process (step S3). Subsequently, since the clipping process will not be performed, the control unit 113 sets clip_cnt to zero (step S4) and proceeds to step S5.

[0025] In step S5, the control unit 113 performs branching processing according to the charging status estimated in step S1. If charging is complete, the control unit 113 writes "3" to the current estimated range cur_lv to indicate the third level (step S6). Then, the control unit 113 transmits the current estimated range cur_lv to the communication terminal 200 (step S51). In addition, the control unit 113 writes the value of the current estimated range cur_lv to the variable of the previous estimated range pre_lv for the next remaining charge estimation process (step S52), and updates pre_time to the current time (step S53). Then, one remaining charge estimation process is completed.

[0026] According to the processing in steps S5 to S6, if the charging status is complete, the estimated range cur_lv is determined to be the third level. Therefore, even if the temperature of the secondary battery 102 is within the caution temperature range and charging is completed at a low voltage, the estimated range cur_lv will be the third level, which is the range for full charge, regardless of the voltage. If the configuration were such that the estimated range cur_lv is determined according to the voltage even when the charging status is complete, then if the secondary battery 102 is within the caution temperature range, the voltage for full charge may be set low, and the estimated range cur_lv may be other than the third level when charging is complete. In such a case, the user may feel a sense of unease, thinking that charging should be complete but it has not reached full charge. However, according to this embodiment, it is possible to suppress the user from feeling such a sense of unease.

[0027] In the branching process of step S5, if the estimated charging status is non-charging or a charging error, the control unit 113 first determines a provisional range cur0_lv using the voltage cur_vol of the secondary battery 102 and the first table 113c (steps S11 to S15). The correspondence between the voltage range and the remaining charge range in the first table 113c is as described above. The first table 113c may be stored alone in the storage unit 113a as shown in Figure 1, or it may be stored as program code as shown in block B113c in Figure 3.

[0028] Once the provisional range cur0_lv is determined, the control unit 113 then determines whether the previous estimated range pre_lv has been invalidated by the reset process in step S3 (step S16). If the answer is NO, the control unit 113 compares the previous estimated range pre_lv with the provisional range cur0_lv (step S17). If, as a result, the previous estimated range pre_lv is invalid, or the provisional range cur0_lv is less than or equal to the previous estimated range pre_lv, the control unit 113 decides not to perform the clipping process described later. That is, the control unit 113 decides the provisional range cur0_lv to be the current estimated range cur_lv (step S18). Furthermore, since the control unit 113 does not perform the clipping process, it writes zero to clip_cnt (step S19) and proceeds to step S51.

[0029] On the other hand, if the determination in steps S16 and S17 shows that the previous estimated range pre_lv is a valid value and that the previous estimated range pre_lv is lower than the provisional range cur0_lv, the control unit 113 performs clipping (step S20). Clipping is a process that keeps the value of the estimated range cur_lv at the previous estimated range pre_lv so that the value does not show an abnormal change. When the charging status is non-charging or there is a charging error, an increase in the remaining charge is an abnormal change, and clipping is effective when such an abnormal change occurs. In clipping, the control unit 113 determines the same value as the previous estimated range pre_lv as the current estimated range cur_lv (step S20). Then, the control unit 113 adds "1" to clip_cnt, which indicates the number of consecutive clipping operations (step S21), and proceeds to step S51.

[0030] Then, the control unit 113 performs the processing described in steps S51 to S53, and the estimated range cur_lv determined in this process is sent to the communication terminal 200. Then, one remaining amount estimation process is completed.

[0031] In the branching process of step S5, if the estimated charging status is charging, the control unit 113 first determines a provisional range cur0_lv using the voltage cur_vol of the secondary battery 102 and the second table 113d (steps S31 to S35). The correspondence between the voltage range and the remaining charge range in the second table 113d is as described above. The second table 113d may be stored alone in the storage unit 113a as shown in Figure 1, or it may be stored as program code as shown in block B113d in Figure 4.

[0032] Once the provisional range cur0_lv is determined, the control unit 113 then determines whether the previous estimated range pre_lv has been invalidated by the reset process in step S3 (step S36). If the answer is NO, the control unit 113 compares the previous estimated range pre_lv with the provisional range cur0_lv (step S37). If, as a result of these comparisons, the previous estimated range pre_lv is invalid, or the provisional range cur0_lv is greater than or equal to the previous estimated range pre_lv, the control unit 113 decides not to perform the clipping process. In other words, the control unit 113 determines the provisional range cur0_lv as the current estimated range cur_lv (step S38). Furthermore, since the control unit 113 does not perform the clipping process, it writes zero to clip_cnt (step S39) and proceeds to step S51.

[0033] On the other hand, if the determination in steps S36 and S37 shows that the previous estimated range pre_lv is a valid value and the provisional range cur0_lv is lower than the previous estimated range pre_lv, the control unit 113 performs clipping (step S40). The clipping process is as described above. When the charging status is charging, a decrease in the remaining charge is an abnormal change, and the clipping process is effective when such an abnormal change occurs. In the clipping process, the control unit 113 determines the current estimated range cur_lv to be the same value as the previous estimated range pre_lv (step S40). Then, the control unit 113 adds "1" to clip_cnt, which indicates the number of consecutive clipping operations (step S41), and proceeds to step S51.

[0034] Then, the control unit 113 performs the processing described in steps S51 to S53, and the estimated range cur_lv determined in this process is sent to the communication terminal 200. Then, one remaining amount estimation process is completed.

[0035] Next, the operation of the clipping process will be explained with reference to Figure 5. In Figure 5, the charging status switches from charging to not charging at timing t1. When switching occurs, there may be a delay ΔT before the switch can be identified from the charging status information. Also, at timing t1, the voltage of the secondary battery 102 drops by one level as the actual charging status switches to not charging. On the other hand, the control unit 113 estimates that the charging status is charging even though it is not charging, and therefore determines a provisional range cur0_lv using the second table 113d corresponding to charging. As a result, although the actual remaining charge range is the third level, the control unit 113 determines the provisional range cur0_lv to be the second level. However, in this embodiment, due to the clipping process in step S40 of Figure 4, during the delay ΔT period, the control unit 113 does not adopt the provisional range cur0_lv as the estimated range cur_lv, but instead retains the value of the previous estimated range pre_lv. Therefore, when the charging status changes, it is possible to prevent situations in which the estimated range of remaining charge and the display pattern of the remaining charge symbol 201a temporarily change incorrectly.

[0036] Next, the operation of the clipping process will be explained with reference to Figure 6. In Figure 6, the charging status switches from non-charging to charging at timing t2. At the time of the switch, a delay ΔT may occur before the switch can be identified from the charging status information. Also, at timing t2, the voltage of the secondary battery 102 rises by one level as the actual charging status switches to charging. On the other hand, the control unit 113 estimates that the charging status is non-charging, even though the charging status is charging, and therefore determines a provisional range cur0_lv using the first table 113c corresponding to non-charging. As a result, although the actual remaining charge range is the second level, the control unit 113 determines the provisional range cur0_lv to be the third level. However, in this embodiment, due to the clipping process in step S20 of Figure 3, during the delay ΔT period, the control unit 113 does not adopt the provisional range cur0_lv as the estimated range cur_lv, but instead retains the value of the previous estimated range pre_lv. Therefore, when the charging status changes, it is possible to prevent situations in which the estimated range of remaining charge and the display pattern of the remaining charge symbol 201a temporarily change incorrectly.

[0037] As described above, the battery management system 110, battery management method, and program 113b of this embodiment provide the following effects. Specifically, the charging control unit 112 and the control unit 113 are provided separately as a prerequisite configuration. The control unit 113 determines a provisional range of remaining charge based on charging status information and the voltage of the secondary battery 102. On the other hand, the control unit 113 determines the current estimated range based on a comparison between the past estimated range and the provisional range of remaining charge. Therefore, even if an error occurs in estimating the charging status when the charging status changes, and this error affects the determination of the provisional range, the control unit 113 can perform the estimation range determination process that addresses the error. Thus, it can contribute to accurate estimation of remaining charge.

[0038] Furthermore, the battery management system 110 of this embodiment includes a communication unit 114 that acts as a transmission unit to send the estimated range of the remaining charge to the outside of the battery management system 110. Based on the estimated range sent to the outside by the communication unit 114, the display of the pattern 201a on the display unit 201 of the communication terminal 200 is updated. Therefore, the estimation range determination process that addresses the aforementioned errors can prevent the transmission of an incorrect estimated charge result and the notification of an unnatural and incorrect estimated charge result from the display unit 201 to the user.

[0039] In the above embodiment, a communication unit 114 capable of communicating with a communication terminal 200 was shown as an example of a transmission unit that sends the estimated range to the outside. However, the transmission unit is not limited to this configuration, and for example, it may be configured to send a signal indicating the estimated range of the remaining charge to a notification unit provided in the electrical device 100. The notification unit may be configured to notify the user of the remaining charge in various ways, such as display, sound, or light emission.

[0040] According to the battery management system 110 of this embodiment, the control unit 113 further has a prerequisite configuration in which it performs a remaining charge estimation process that determines the estimated range of the remaining charge based on a request from outside the battery management system 110. With this prerequisite configuration, the remaining charge estimation process is not performed unnecessarily, and the power consumption of the system can be reduced. On the other hand, in the above prerequisite configuration, the remaining charge estimation process is performed discontinuously, so the control unit 113 must perform the charging status estimation process discontinuously, and therefore, when the charging status changes, there is a tendency for delays to occur in identifying the change. Here, let's assume that the charging status is estimated from the signal pattern of the light-emitting part that represents the charging status. In this case, if the estimation process is performed continuously, the signal pattern can be quickly identified by using the signal of the light-emitting part input in the previous estimation process in the current estimation process as well. On the other hand, if the estimation process is discontinuous, it is not possible to use the previous signal as described above, and it takes time to correctly identify the signal pattern. Therefore, in the above prerequisite configuration, the estimation range determination process that addresses the aforementioned errors is particularly useful.

[0041] Furthermore, according to the battery management system 110 of this embodiment, the control unit 113 compares the provisional range of remaining charge (cur0_lv) with the past estimated range (pre_lv) during the period when the battery is estimated to be not charging based on the charging status information (step S17 in Figure 3). Then, if the past estimated range (pre_lv) is lower, the control unit 113 performs a clipping process (step S20 in Figure 3) to set the past estimated range (pre_lv) as the current estimated range (cur_lv). This clipping process can suppress errors in the estimated range that tend to occur when the charging status switches from not charging to charging, as shown in Figure 6.

[0042] Furthermore, according to the battery management system 110 of this embodiment, the control unit 113 compares the provisional range of remaining charge (cur0_lv) with the past estimated range (pre_lv) during the period estimated to be charging based on the charging status information (step S37 in Figure 4). Then, if the provisional range (cur0_lv) is lower, the control unit 113 performs a clipping process (step S40 in Figure 4) to set the past estimated range (pre_lv) as the current estimated range (cur_lv). This clipping process can suppress errors in the estimated range that tend to occur when the charging status switches from charging to not charging, as shown in Figure 5.

[0043] In the above embodiment, an example was shown in which the previous estimation range pre_lv was applied as the past estimation range. However, various modifications can be applied, such as applying the average value of the estimation ranges within a predetermined past period, including the previous one, as the past estimation range, for example, when the resolution of the estimation range is small. Also, if the previous and the one before that were performed within a short period, the estimation range of the one before that may be applied as the past estimation range.

[0044] According to the battery management system 110 of this embodiment, the control unit 113 further performs a reset process (step S3 in Figure 2) to disable clipping when conditions are met that reduce the reliability of clipping. The above conditions include, as shown in step S2 in Figure 2, a change in the estimated charge status, the elapsed time since the previous determination of the estimation range, or the continuous execution of clipping a threshold number of times (e.g., 5 times) or more. This reset process prevents clipping from being performed in a situation where the reliability of clipping has decreased, thereby preventing the estimated range of the remaining charge from being incorrectly determined. The threshold number of clipping operations should be set to a number that reduces erroneous estimations even when the charge status switches in various ways, based on the delay ΔT until the switch in the charge status can be identified and the minimum period time for estimating the remaining charge. The threshold time should be set to a number that reduces erroneous estimations even when the charge status switches in various ways, based on the slope of the charge / discharge characteristic curve (amount of voltage change per unit time). When the charging status changes in various ways, this may include, for example, a situation where the remaining charge is being estimated while charging, then the estimation of the remaining charge is paused and charging stops, and immediately afterward, charging resumes and the remaining charge is estimated again.

[0045] Furthermore, according to the battery management system 110 of this embodiment, the control unit 113 estimates at least the states of not charging, charging complete, and charging based on the charging status information. In addition, the control unit 113 has a first table 113c and a second table 113d that show the relationship between the voltage of the secondary battery 102 and multiple ranges of remaining charge, respectively, when it is not charging and when it is charging. Therefore, during periods when there is no change in the charging status, the control unit 113 can accurately estimate the range of remaining charge using the estimated charging status and the first table 113c and the second table 113d.

[0046] Furthermore, the battery management system 110 of this embodiment includes a charge control unit 112, a voltage sensor 121, and a control unit 113 that receives charge status information from the charge control unit 112 and the voltage value of the secondary battery 102. The control unit 113 determines the estimated range of remaining charge based on the charge status information and the voltage value. Furthermore, when the charge status is constant, the control unit 113 changes the estimated range from the second level to the third level or vice versa when the voltage changes across a threshold voltage (for example, 3.90V during charging or 3.75V when not charging). On the other hand, when the charge status switches from charging to not charging or vice versa, the control unit 113 does not change the estimated range even if the voltage changes across the threshold voltage, as shown at timing t1 in Figure 5 or timing t2 in Figure 6. Therefore, as shown in Figures 5 and 6, it is possible to suppress the control unit 113 from incorrectly determining the estimated range of remaining charge.

[0047] Embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. For example, the above embodiments show an example based on a configuration in which one secondary battery is charged using one charger, but the present invention may also be applied to a configuration in which one or more control units estimate the remaining charge of multiple secondary batteries charged using multiple chargers. Furthermore, the secondary battery and charger may be a secondary battery that drives an electric vehicle and a charger that takes power from a charging station for the vehicle. In addition, in a system in which the device having the secondary battery and the device having the charger are separate components, a configuration in which a control unit in the system similarly estimates the remaining charge may be adopted. For example, the details shown in the embodiments can be appropriately modified without departing from the spirit of the invention. [Explanation of Symbols]

[0048] 100 Electrical device, 102 Secondary battery, 110 Battery management system, 111 Charger, 112 Charging control unit, 113 Control unit, 121 Voltage sensor, 200 Communication terminal

Claims

1. A charge control unit that controls the charging of a secondary battery, A voltage sensor for detecting the voltage of the secondary battery, A control unit that estimates which of several ranges the remaining charge of the secondary battery falls within, and sets that range as the estimated range. Equipped with, The control unit, Based on the detected voltage in each of the multiple charging conditions of the charging control unit, a provisional range is determined that provisionally indicates which of the multiple ranges the remaining charge falls into. Based on a comparison of the aforementioned provisional range and the previously estimated range, the current estimated range is estimated. Battery management system.

2. The system further includes a sending unit that sends the estimated range to the outside of the battery management system. The battery management system according to claim 1.

3. The control unit estimates the estimated range based on an external request from the battery management system. The battery management system according to claim 1.

4. The control unit, If, during a period in which the charging status is estimated to be non-charging, the past estimated range is lower than the provisional range, a clipping process is performed to set the past estimated range as the current estimated range. The battery management system according to claim 1.

5. The control unit, During the period in which the charging status is estimated to be charging, if the provisional range is lower than the previously estimated range, a clipping process is performed to set the previously estimated range as the current estimated range. The battery management system according to claim 1.

6. The control unit, If there is a change in the estimated charging status, if a threshold time has elapsed since the last determination of the estimated range, or if the clipping process has been executed more times than the threshold number of times consecutively, the clipping process will not be executed. The battery management system according to claim 4 or claim 5.

7. The control unit, The aforementioned charging status is estimated to be at least non-charging, fully charged, and charging, and includes a first table showing the relationship between the voltage and the remaining charge range when non-charging, and a second table showing the relationship between the voltage and the remaining charge range when charging, Based on the first table, the provisional range when it is estimated to be non-charged is determined, Based on the second table, the provisional range when charging is estimated is determined. The battery management system according to claim 1.

8. A charge control unit that controls the charging of a secondary battery, A voltage sensor for detecting the voltage of the secondary battery, The detected voltage is acquired in each of the multiple charging states of the charging control unit. A control unit that estimates which of several ranges the remaining charge of the secondary battery falls within, and sets that range as the estimated range. Equipped with, The control unit, When the charging status is constant, the estimation range is changed when the voltage changes across the threshold voltage, When the charging status switches from non-charging to charging or from charging to non-charging, the estimated range is not changed even if the voltage changes across the threshold voltage. Battery management system.

9. The charging control unit controls the charging of the secondary battery. A control unit different from the aforementioned charging control unit estimates which of several ranges the remaining charge of the secondary battery falls within, and defines that range as the estimated range. The control unit, Based on the voltage of the secondary battery detected in each of the multiple charging states of the charging control unit, a provisional range is determined that provisionally indicates which of the multiple ranges the remaining charge falls into. The current estimated range is estimated based on a comparison of the aforementioned provisional range with the previously estimated range. How to manage batteries.

10. Computers, This function acts as an estimation means to estimate which of several ranges the remaining charge of a secondary battery falls into, and uses that range as the estimated range. The estimation means determines a provisional range that provisionally indicates which of the plurality of ranges the remaining charge is in, based on the voltage of the secondary battery detected in each of the plurality of charging states of the secondary battery. The current estimated range is estimated based on a comparison of the aforementioned provisional range with the previously estimated range. program.

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