Patent Publication Number: US-2021194071-A1

Title: Secondary battery management device, secondary battery management method, and non-transitory computer readable storage medium

Description:
BACKGROUND 
     Technical Fields 
     The present invention relates to a secondary battery management device, a secondary battery management method, and a non-transitory computer readable storage medium. 
     Priority is claimed on Japanese Patent Application No. 2019-229655, filed on Dec. 19, 2019, the contents of which are incorporated herein by reference. 
     Description of Related Art 
     In recent years, a system, which includes a secondary battery capable of being charged and discharged and charges and discharges the secondary battery when necessary, has been used in various fields. For example, in the field of electric power, the system is used to shift a part of daytime electric power consumption to nighttime electric power (a peak shift). In such a system, it is important to accurately detect information representing a state of the secondary battery so that the system is operated safely and efficiently for a long period. The information representing the state of the secondary battery is, for example, the remaining capacity or a charging rate (a state of charge, hereinafter also referred to as an “SOC”) of the secondary battery or the like. 
     Incidentally, in many conventional systems, information representing a detected state of a secondary battery is managed independently inside a secondary battery unit. If a manufacturer of the secondary battery unit is different, information representing the state of the secondary battery and a charging and discharging control management method are different. Conventionally, because information representing the state of the secondary battery is managed internally as described above, there is a problem in accurately ascertaining the state of the secondary battery and appropriately controlling the charging and discharging of the secondary battery. 
     SUMMARY 
     A secondary battery management device may be communicably connected to a secondary battery unit including a secondary battery, and manages the secondary battery unit. The secondary battery management device may be configured to: request the secondary battery unit to transmit a voltage and a state value of the secondary battery; receive the voltage and the state value of the secondary battery transmitted from the secondary battery unit; calculate a value of correction of the state value on the basis of the voltage and the state value which have been received; and transmit the calculated value of correction to the secondary battery unit in order to apply the calculated value of correction. 
     Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a configuration of a secondary battery management system according to a first embodiment. 
         FIG. 2  is a diagram showing an example of a hardware configuration of a management device shown in  FIG. 1 . 
         FIG. 3  is a diagram showing an example of charging characteristics of a secondary battery. 
         FIG. 4  is a flowchart showing an example of a process of the management device according to the present embodiment. 
         FIG. 5  is a flowchart showing an example of a process of a secondary battery unit according to the present embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The embodiments of the present invention will be now described herein with reference to illustrative preferred embodiments. Those skilled in the art will recognize that many alternative preferred embodiments can be accomplished using the teaching of the present invention and that the present invention is not limited to the preferred embodiments illustrated herein for explanatory purposes. 
     An aspect of the present invention is to provide a secondary battery management device, a secondary battery management method, and a non-transitory computer readable storage medium capable of externally managing information representing a state of a secondary battery. 
     Hereinafter, embodiments of a secondary battery management device, a secondary battery management method, and a non-transitory computer readable storage medium according to the present invention will be described with reference to the drawings. 
     [Overview] 
     A management device according to the embodiment of the present invention enables information representing a state of a secondary battery to be externally managed. Specifically, the management device can correct the information representing the state of the secondary battery according to control from outside of the secondary battery unit. That is, the management device can correct the information representing the state of the secondary battery at a planned timing. Also, the information representing the state of the secondary battery can be corrected according to a unified method without depending upon a technique of a manufacturer of a secondary battery unit. 
     It is important for a system equipped with a secondary battery capable of being charged and discharged to accurately detect the information representing the state of the secondary battery (hereinafter referred to as a “state value”). By accurately detecting the state value, the system can be operated safely and efficiently for a long period. The state value of the secondary battery is, for example, the remaining capacity, an SOC, the maximum capacity, a degree of deterioration (a state of health, hereinafter also referred to as an “SOH”), or the like of the secondary battery. 
     For example, as one of methods of calculating the remaining capacity, there is a method using an integrated value of electric current. In this method, the remaining capacity is calculated by integrating electric currents of charging and discharging to acquire an integrated value and adding an integrated value to the initial remaining capacity. When the secondary battery unit is used for a long period, a measurement error of the electric current value is accumulated, and an error occurs between the calculated remaining capacity and the actual remaining capacity. In order to correct the error, the remaining capacity is corrected. However, the management of the state value such as correction is performed independently inside the secondary battery unit. Thus, the state value may be corrected at a timing which is not intended by the user and charging and discharging control may not be performed as planned. 
     Also, there may be efforts to make a function of a virtual power plant by utilizing distributed power sources such as virtual power plants. This system includes secondary battery units from several different manufacturers. A state value correction algorithm and a correction timing differ in accordance with a manufacturer or type of the secondary battery unit. Thus, it may be difficult to manage state values of a plurality of secondary battery units according to a unified method. 
     A concept of the state value of the secondary battery also differs in accordance with the manufacturer or type of the secondary battery unit. For example, an SOC value at the time of full charging may differ between a plurality of secondary battery units. Thus, it may be difficult to utilize state values of a plurality of secondary battery units according to a unified concept. 
     Also, if an attempt is made to detect a state value with high accuracy by performing an advanced calculation process inside each secondary battery unit, it is necessary to provide a high-performance processor in the secondary battery unit. However, the cost of the system is increased by mounting a high-performance processor inside each secondary battery unit. 
     Therefore, the secondary battery management device of the present embodiment is connected to a secondary battery unit including a secondary battery so that communication with the secondary battery unit is possible and externally manages the secondary battery unit. The management device requests the secondary battery unit to transmit a voltage and a state value of the secondary battery and receives the voltage and state value of the secondary battery transmitted from the secondary battery unit. The management device calculates a value of correction of the state value on the basis of the voltage and the state value that have been received and transmits the calculated value of correction to the secondary battery unit so that the calculated value of correction is applied. Thereby, information representing the state of the secondary battery can be externally managed. 
     First Embodiment 
     &lt;Configuration of Secondary Battery Management System&gt; 
     An example of a configuration of a secondary battery management system according to an embodiment of the present invention will be described.  FIG. 1  is a block diagram showing a configuration of a secondary battery management system according to a first embodiment. The secondary battery management system shown in  FIG. 1  includes a management device  100  and a plurality of secondary battery units  200 A to  200 C. Users of the secondary battery management system are, for example, an electric power provider, an information service provider, a facility manager, an aggregator, and the like. 
     The plurality of secondary battery units  200 A to  200 C shown in  FIG. 1  may be secondary battery units  200  made by different manufacturers. Although an example in which the secondary battery management system includes the plurality of secondary battery units  200 A to  200 C is shown in the example of  FIG. 1 , the number of secondary battery units  200  may be one. Hereinafter, when the plurality of secondary battery units  200 A to  200 C are not distinguished, they are referred to as secondary battery units  200 . 
     The management device  100  and each secondary battery unit  200  are connected via a network. The management device  100  controls the charging and discharging of each secondary battery unit  200  and manages a state value of each secondary battery  201 . Also, the management device  100  may be a server in a cloud environment. 
     The management device  100  includes a controller  101  and a correction calculator  102 . The controller  101  controls charging and discharging of each secondary battery unit  200 . The controller  101  outputs a charging and discharging control instruction to each secondary battery unit  200  according to a charging and discharging plan. The correction calculator  102  requests the secondary battery unit  200  to transmit data used for calculating the value of correction of the state value and calculates the value of correction on the basis of the data that has been received. The correction calculator  102  causes the calculated value of correction to be applied to the secondary battery unit  200  at a timing designated for the secondary battery unit  200 . 
     The state value in the present embodiment represents, for example, the remaining capacity, an SOC, the maximum capacity, an SOH, or the like of the secondary battery. The remaining capacity (Ah) is the remaining value of electricity with which the secondary battery can be discharged at a current point in time. The maximum capacity (Ah) is the maximum value of electricity that can be stored in a secondary battery within a specified voltage range. The SOC (%) represents a charging rate of the secondary battery and is calculated according to the formula “remaining capacity maximum capacity×100.” The SOH (%) represents the degree of deterioration of the secondary battery and is calculated by the formula “maximum capacity at current point in time=initial maximum capacity×100.” Also, in the present embodiment, an example in which the remaining capacity is corrected as a state value is shown. 
     The secondary battery unit  200  includes a secondary battery  201 , a charging and discharging controller  202 , a measurer  203 , an electric current value integrator  204 , and a remaining capacity calculator  205 . Here, the configuration of one secondary battery unit  200  will be described, but the same applies to the configuration of the other secondary battery unit  200 . 
     The secondary battery  201  is a lithium ion battery, a nickel hydrogen battery, or the like. The charging and discharging controller  202  controls charging and discharging states of the secondary battery  201  according to an instruction output from the controller  101  of the management device  100 . The measurer  203  measures an electric current value and a voltage value of the secondary battery  201  at predetermined intervals. The measurer  203  includes, for example, a voltage sensor, an electric current sensor, and the like. The measurer  203  outputs the electric current value and the voltage value that have been measured to the electric current value integrator  204  and the correction calculator  102 . 
     The electric current value integrator  204  integrates electric current values measured by the measurer  203  according to a Coulomb counting process and calculates the integrated value of the electric current values for a predetermined period. The electric current value integrator  204  performs a subtraction operation on the integrated value at the time of discharging and performs an addition operation on the integrated value at the time of charging. That is, the electric current value integrator  204  integrates an electric current flowing into the secondary battery  201  and an electric current flowing out from the secondary battery  201  to calculate an integrated value for a predetermined period. 
     The remaining capacity calculator  205  updates the remaining capacity by adding the remaining capacity to the integrated value. In response to a request from the management device  100 , the remaining capacity calculator  205  outputs measured values obtained by measuring the voltage value and the electric current value and the remaining capacity calculated by the electric current value integrator  204  to the management device  100 . Also, when the value of correction of the remaining capacity is received from the management device  100 , the remaining capacity calculator  205  updates the remaining capacity according to the value of correction. 
       FIG. 2  is a diagram showing an example of a hardware configuration of the management device  100  shown in  FIG. 1 . The management device  100  is a computer including a central processing unit (CPU)  110 , a communication module  111 , an interface  112 , and the like. The management device  100  further includes a random access memory (RAM)  113 , a read only memory (ROM)  115 , a hard disk drive (HDD)  116 , and the like. 
     The RAM  113  stores a management program  114 . The CPU  110  reads and executes the management program  114  stored in the RAM  113  or the like. Thereby, the management device  100  implements the functions of the controller  101  and the correction calculator  102 . Some of these functions of the controller  101  and the correction calculator  102  may be implemented by an electronic circuit. 
     The communication module  111  is connected to each secondary battery unit  200 . The communication module  111  may perform wireless communication with each secondary battery unit  200  or may perform wired communication with each secondary battery unit  200 . Also, the management device  100  may be connected to a terminal device (not shown) via the communication module  111 . For example, by operating the terminal device, the user causes the terminal device to display the value of correction calculated by the management device  100  or the remaining capacity after the correction. 
     Here, a general state value correction method will be described with reference to  FIG. 3 . A method of calculating the value of correction in the present embodiment is not limited to the example of  FIG. 3 . There are various generally known methods of correcting the state value. 
     &lt;Remaining capacity correction method&gt; 
       FIG. 3  is a diagram showing an example of charging characteristics of the secondary battery. The horizontal axis of  FIG. 3  represents the remaining capacity (Ah) and the vertical axis represents a voltage value (V).  FIG. 3  shows the transition of the voltage value when the secondary battery is charged while a constant current is flowing. A voltage of the secondary battery changes with a change in the remaining capacity of the secondary battery. In the example of  FIG. 3 , an SOC of “0%” is shown when the voltage value is the minimum and an SOC of “100%” is shown when the voltage value is the maximum. 
     As shown in  FIG. 3 , the relationship between the voltage of the secondary battery and the remaining capacity has predetermined characteristics. For example, as a characteristic, a distinctive feature appears in a relationship in a certain SOC section. An SOC value or an SOC section in which a distinctive feature appears is referred to as a feature point F 1  or a feature section F 2 . The feature point F 1  and the feature section F 2  differ according to, for example, characteristics of the secondary battery. The value of correction of the remaining capacity can be calculated using the feature point or the feature section. 
     For example, an example of a method of calculating the value of correction when the feature point F 1  has an SOC of “80%” will be shown. The voltage value and the remaining capacity measured when the secondary battery  201  has an SOC of “80%” are acquired. On the basis of characteristics shown in  FIG. 3  stored in advance, the remaining capacity corresponding to the measured voltage value is acquired. A difference between the remaining capacity acquired on the basis of the characteristics ( FIG. 3 ) and the remaining capacity when the secondary battery  201  has an SOC of “80%” is acquired as a value of correction. 
     Characteristics of a relationship between the remaining capacity and the voltage differ according to a manufacturer or type of the secondary battery. Thus, the feature point F 1  is not limited to the example of  FIG. 3 . The feature point F 1  may have an SOC of “100%” or another value. For example, when the SOC is “100%,” the SOC in the fully charged state is corrected to a value of “100%” by fully charging the secondary battery. However, in this case, the quality of the secondary battery tends to deteriorate by fully charging the secondary battery. 
     Also, an example of a method of calculating the value of correction when the feature section F 2  has an SOC of “30% to 40%” will be shown. The voltage value and the remaining capacity measured when the secondary battery  201  has an SOC of “30% to 40%” are acquired. On the basis of the characteristics ( FIG. 3 ) stored in advance, the remaining capacity corresponding to each measured voltage value is acquired. A difference between the remaining capacity acquired on the basis of the characteristics ( FIG. 3 ) and the remaining capacity when the secondary battery  201  has an SOC of “30% to 40%” is acquired as a value of correction. 
     As described above, the calculation of the value of correction of the remaining capacity is not limited to this example. For example, in addition to the voltage value and the remaining capacity, the value of correction of the remaining capacity may be further calculated on the basis of a temperature, a resistance value, or the like. The value of correction can be further obtained with higher accuracy on the basis of a temperature, a resistance value, and the like. 
     There is also a method of calculating the value of correction with high accuracy using complicated calculation processing. Such a method includes a method of obtaining an open current voltage (OCV) from which a change in voltage during charging and discharging is excluded and a method of using differential characteristics. The differential characteristic “dV/dQ” represents a ratio of a change value “dV” of the voltage value of the secondary battery to a change value “dQ” of the remaining capacity. Using a relationship between the differential characteristic “dV/dQ” and the remaining capacity, the value of correction can be obtained with higher accuracy. 
     &lt;Flow of Correction Calculation Process&gt; 
       FIG. 4  is a flowchart showing an example of a process of the management device  100  according to the present embodiment.  FIG. 5  is a flowchart showing an example of a process of each secondary battery unit  200  according to the present embodiment. As described above, in the present embodiment, an example in which the remaining capacity is corrected will be shown. 
     First, a flow of a process of the management device  100  will be described according to the flowchart of  FIG. 4 . The controller  101  of the management device  100  starts an operation of a correction condition with respect to the secondary battery unit  200  (step S 11 ). Specifically, the controller  101  controls charging and discharging of the secondary battery unit  200  so that the secondary battery has an SOC of the feature point F 1  or the feature section F 2  described with reference to  FIG. 3 . In this example, the controller  101  controls the charging and discharging of the secondary battery unit  200  so that at least one of charging and discharging is performed at an SOC of “30% to 40%.” 
     More specifically, for example, when the SOC at a current point in time is “20%,” the controller  101  sets an electric current flowing through the secondary battery  201  to a constant current and causes the secondary battery  201  to be charged until the SOC becomes “40%.” On the other hand, for example, when the current SOC is “40%,” the controller  101  causes the secondary battery  201  to be discharged until the SOC becomes “30%.” 
     When the secondary battery  201  satisfies the correction condition, the correction calculator  102  of the management device  100  outputs a data transmission request to the secondary battery unit  200  (step S 12 ). Data is measured values obtained by measuring the voltage value and the electric current value and the remaining capacity in a state in which the SOC of the secondary battery  201  is included in the feature section F 2 . That is, the correction calculator  102  requests the secondary battery unit  200  to transmit the measured values obtained by measuring the voltage value and the electric current value and the remaining capacity at predetermined time intervals in the state of an SOC of “30% to 40%.” The correction calculator  102  receives the data from the secondary battery unit  200  and stores the data in a memory such as the RAM  113  or the HDD  116 . The correction calculator  102  may receive the data from the secondary battery unit  200  at predetermined time intervals or may collectively receive the data. 
     The correction calculator  102  calculates the value of correction of the remaining capacity on the basis of the data received from the secondary battery unit  200  (step S 13 ). The correction calculator  102  calculates the value of correction according to a predetermined algorithm. Also, an algorithm for calculating the value of correction may be designated in advance from a plurality of algorithms. 
     For example, the correction calculator  102  obtains the remaining capacity corresponding to the measured value of the voltage value in the state of an SOC of “30% to 40%” on the basis of the characteristics ( FIG. 3 ) of the secondary battery  201  stored in advance. The correction calculator  102  obtains a difference between the obtained remaining capacity and the remaining capacity received from the secondary battery unit  200  as the value of correction. Also, in the present embodiment, the correction calculator  102  acquires an electric current value to verify whether or not charging and discharging are to be controlled in a state in which a constant current is flowing through the secondary battery  201 . 
     As described above, the management device  100  outside of the secondary battery unit  200  calculates the value of correction of the remaining capacity. Also, when a plurality of secondary battery units  200  are provided, the management device  100  calculates the value of correction using an algorithm common to the plurality of secondary battery units  200 . Thereby, the state value of the secondary battery can be corrected according to a unified method without depending upon a technique of the manufacturer of the secondary battery unit  200 . 
     The correction calculator  102  outputs a calculated value of correction “AQc” to the secondary battery unit  200  at a timing designated for the secondary battery unit  200  (step S 14 ). Thereby, the remaining capacity “Q” of the secondary battery unit  200  is corrected. Information such as a date and time designated as the timing is stored in a memory such as the RAM  113  or the HDD  116 . The CPU  110  performs control for causing the value of correction to be applied to the secondary battery unit  200  at a designated timing according to the management program  114 . 
     The timing of step S 14  is, for example, a point in time when the user has issued a correction instruction via the management device  100 . Alternatively, the timing may be a predetermined date and time designated in advance or a periodic date and time designated in advance. As described above, the remaining capacity is applied at the timing designated in advance. Thus, it is possible to restrict the occurrence of a situation in which the remaining capacity is corrected at a timing that is not intended by the user and therefore charging and discharging control cannot be performed as planned. 
     Also, when a plurality of secondary battery units  200  are provided, the management device  100  causes the value of correction to be applied at a timing designated for each of the plurality of secondary battery units  200 . In this case, timing information such as a date and time is stored in the memory with respect to each of the plurality of secondary battery units  200 . The CPU  110  performs control for causing the value of correction corresponding to each secondary battery unit  200  to be applied at a timing designated for each secondary battery unit  200  according to the management program  114 . Thereby, the management device  100  can correct the remaining capacity at a timing suitable for each secondary battery unit  200 . 
     Also, the management device  100  performs the processing of steps S 11  to S 13  at the designated timing. For example, the management device  100  may perform the processing of steps S 11  to S 13  immediately before the designated timing. Alternatively, the management device  100  may perform the processing of steps S 11  to S 13  in advance on the day before the designated timing or the like. 
     For example, the CPU  110  reads in advance information about a timing at which the value of correction of the secondary battery unit  200  will be applied from the memory to acquire the information. The CPU  110  sets a processing period for executing the processing of steps S 11  to S 13  according to the acquired information about the timing and controls the execution of the process. Also, a processing period such as a designated period immediately before the timing may be further designated in addition to the timing. Thereby, the remaining capacity can be externally managed more flexibly. 
     Also, the processing of steps S 11  and S 12  and the processing of step S 13  may be executed in different periods. That is, the correction calculator  102  may execute a correction condition operation instruction, a data acquisition process, and a value-of-correction calculation process in different periods. For example, the correction calculator  102  may acquire data in advance and calculate the value of correction immediately before the timing at which the value of correction is applied. 
     Next, a flow of a process of the secondary battery unit  200  will be described according to the flowchart of  FIG. 5 . Although not shown in the flowchart, the secondary battery unit  200  receives a correction condition operation instruction from the management device  100 . The secondary battery unit  200  iterates the processing of steps S 21  to S 24  shown below while charging and discharging are being controlled in accordance with the correction condition operation instruction. 
     The measurer  203  of the secondary battery unit  200  measures a voltage value and an electric current value of the secondary battery  201  (step S 21 ). The electric current value integrator  204  of the secondary battery unit  200  integrates measured values obtained by measuring electric current values for a predetermined period (step S 22 ). The electric current value integrator  204  obtains an integrated value “AQ” obtained by integrating the electric current values for the predetermined period (step S 23 ). The remaining capacity calculator  205  of the secondary battery unit  200  adds the integrated value “ΔQ” obtained by integrating the electric current values for the predetermined period to the remaining capacity “Q” that has been retained to update the remaining capacity (step S 24 ). 
     The remaining capacity calculator  205  determines whether or not a data transmission request has been received from the management device  100  (step S 25 ). When the data transmission request has been received (YES in S 25 ), the remaining capacity calculator  205  transmits continuous time-series data in a state in which the correction condition has been satisfied to the management device  100  (step S 26 ). That is, the remaining capacity calculator  205  outputs the measured values (S 21 ) obtained by measuring the voltage value and the electric current value at the time of an SOC of “30% to 40%” and the remaining capacity (S 24 ) to the management device  100 . 
     The remaining capacity calculator  205  determines whether or not the value of correction “ΔQc” has been received from the management device  100  (step S 27 ). When the value of correction “ΔQc” has been received (YES in S 27 ), the remaining capacity calculator  205  corrects the remaining capacity according to the received value of correction “ΔQc” (step S 28 ). That is, the remaining capacity calculator  205  updates the remaining capacity by adding the received value of correction “ΔQc” to the latest remaining capacity “Q” updated in step S 24 . 
     After the remaining capacity correction process (step S 28 ), or when the value of correction has not been received (NO in S 27 ), the remaining capacity calculator  205  returns to the processing of step S 21 . 
     As described above, the secondary battery unit  200  iterates a process of detecting the remaining capacity through an integration process while periodically measuring the voltage value and the electric current value. During the process, when the correction condition operation instruction is received from the management device  100 , the secondary battery unit  200  controls the SOC in the state of the feature point or the feature section. The secondary battery unit  200  outputs data for calculating the value of correction in the feature point or the feature section of the SOC to the management device  100 . When the secondary battery unit  200  receives the value of correction from the management device  100  at a timing designated for the secondary battery unit  200 , the secondary battery unit  200  updates the remaining capacity on the basis of the value of correction. 
     Although an example in which the value of correction of the remaining capacity is calculated has been described in the above-described embodiment, the same applies to a case in which the value of correction of the SOC is calculated. The management device  100  may calculate a difference value of the SOC as a value of correction in step S 13 . Alternatively, the SOC may be corrected on the basis of the corrected remaining capacity. 
     Also, in the above-described embodiment, an example in which the management device  100  receives the voltage value, the electric current value, and the remaining capacity from the secondary battery unit  200  has been described. However, the present invention is not limited to this example and the management device  100  may receive only the voltage value and the remaining capacity. Alternatively, the management device  100  may receive other data such as a temperature and a resistance value from the secondary battery unit  200  in addition to the voltage value and the remaining capacity. 
     Also, the feature point F 1  or the feature section F 2  used for calculating the value of correction may differ in accordance with the secondary battery unit  200 . As described above, if a manufacturers or type of the secondary battery unit  200  is different, characteristics of the secondary battery  201  are also different. Therefore, the feature point F 1  or the feature section F 2  is set for each secondary battery  201  in accordance with the characteristics of the secondary battery  201 . Also, the feature point F 1  or the feature section F 2  of each secondary battery unit  200  may be managed by the user via the management device  100 . 
     Modified Examples 
     In the above-described embodiment, an example in which the remaining capacity or the SOC is corrected has been described. The present embodiment is not limited to this example and the present embodiment is also applicable to the correction of the maximum capacity and the SOH. As in the calculation of the value of correction of the remaining capacity, the maximum capacity and the value of correction of the SOH can be calculated on the basis of the voltage value and the remaining capacity. There are various methods for calculating the maximum capacity and the value of correction of the SOH, which are generally known technologies. 
     For example, the management device  100  requests the secondary battery unit  200  to transmit a voltage value and the remaining capacity at a characteristic point or a feature section of the SOC. The management device  100  calculates the value of correction of the maximum capacity on the basis of the voltage value and the remaining capacity received from the secondary battery unit  200 . The management device  100  transmits the value of correction of the maximum capacity to the secondary battery unit  200  at the timing designated by the secondary battery unit  200  and causes the value of correction to be applied. Also, the management device  100  may calculate a difference value of the SOH as the value of correction. Alternatively, the SOH may be corrected on the basis of the corrected maximum capacity. 
     As described above, the management device  100  according to the present embodiment is connected to the secondary battery unit  200  including the secondary battery  201  so that communication with the secondary battery unit  200  is possible and manages the secondary battery unit  200 . The management device  100  requests the secondary battery unit  200  to transmit a voltage and a state value of the secondary battery, and receives the voltage and the state value of the secondary battery  201  transmitted from the secondary battery unit  200 . The management device  100  calculates the value of correction of the state value on the basis of the received voltage and the state value and transmits the value of correction to the secondary battery unit  200  so that the calculated value of correction is applied. 
     Thereby, the management device  100  can issue an instruction for correcting the state value of the secondary battery  201  from outside of the secondary battery unit  200 . That is, a timing of correction of the state value of the secondary battery  201  can be controlled from outside of the secondary battery unit  200 . Thereby, the state value of the secondary battery  201  can be corrected at a timing intended by the user. 
     Therefore, it is possible to restrict the occurrence of a situation in which the state value of the secondary battery  201  is corrected at a timing that is not intended by the user and charging and discharging control cannot be performed as planned. In other words, charging and discharging control can be performed as planned by correcting the state value of the secondary battery  201  at a planned timing. 
     Also, in the present embodiment, the management device  100  outside of the secondary battery unit  200  calculates the value of correction of the state value according to a shared algorithm. Thus, when the secondary battery management system includes a plurality of secondary battery units  200 , the following effects are obtained. That is, the state value can be corrected according to a common algorithm that does not depend on the manufacturer&#39;s technique and the algorithm for use in calculation of the value of correction can be recognized. Also, the concept of the state value can be unified regardless of the manufacturer of the secondary battery unit  200 . As described above, the state value of the secondary battery  201  can be managed according to a unified algorithm or concept. 
     Also, as the management device  100  according to the present embodiment, the management device  100  outside the secondary battery unit  200  has a function of calculating the value of correction of the state value. Thereby, it is not necessary to provide a processor having an advanced calculation function inside each secondary battery unit  200 . Thus, the cost of the secondary battery unit  200  can be reduced. 
     Second Embodiment 
     Although not shown in  FIG. 1 , a secondary battery unit  200  includes a group of cells in which a plurality of single battery cells of the secondary battery  201  are connected in series. When the remaining capacities do not match between the plurality of cells, the remaining capacity of the secondary battery  201  is limited to the remaining capacity of the cell having the smallest remaining capacity. Therefore, discharging control (a cell balance function) between cells is performed to equalize the remaining capacities of cells. 
     Here, an example of control of the cell balance function will be described. For example, in the control of the cell balance function, when a specific cell among a plurality of cells reaches the maximum voltage (a fully charged state), the charging of the cell is stopped and the cell is discharged. Also, for example, a charging instruction is issued with respect to other cells that have not been fully charged. By iterating charging and discharging for the cells connected in series, the plurality of cells is fully charged with respect to the remaining capacity. 
     According to this example, a period in which the secondary battery  201  cannot be used occurs by iterating charging and discharging for the number of cells connected in series. Therefore, it is desirable to implement cell balance without fully charging each cell. However, when an algorithm for analyzing the balance of the remaining capacity among a plurality of cells is implemented inside each secondary battery unit  200 , the cost increases. 
     Therefore, in the management device  100  according to the second embodiment, the management device  100  outside the secondary battery unit  200  implements the cell balance function. That is, the remaining capacity of each cell of the secondary battery unit  200  is detected and discharging control is performed for each cell. The configuration example of the system and the hardware configuration of the management device  100  are similar to those in the first embodiment. The flowchart of the process of the management device  100  and the secondary battery unit  200  is similar to that of the first embodiment except for the following processing. 
     The management device  100  according to the second embodiment requires the secondary battery unit  200  to transmit a voltage and the remaining capacity of each of the plurality of cells. The management device  100  calculates a value of correction of the remaining capacity of each cell on the basis of the voltage and the remaining capacity of each cell that have been received. The management device  100  transmits the calculated value of correction of each cell to the secondary battery unit  200  and issues a discharging control instruction for each cell on the basis of the remaining capacity after the correction of each cell. 
     The management device  100  compares the remaining capacities between a plurality of cells and controls discharging times of some cells having the remaining capacities which are relatively high. That is, the management device  100  causes a cell having the remaining capacity which is relatively high to be discharged. Thereby, the remaining capacities of a plurality of cells can be equalized without fully charging each cell. Also, it is possible to restrict the occurrence of a period that cannot be used for the execution of the cell balance. In this manner, the management device  100  can manage the remaining capacity of each cell of the secondary battery unit  200  and manage the discharging of each cell. 
     Although an example in which the value of correction of the remaining capacity of each of the plurality of cells is calculated has been described in the second embodiment, the present invention is effective even if the value of correction of the SOC is calculated as in the first embodiment. The management device  100  may also calculate the difference value of the SOC as the value of correction of the state value of each cell. Alternatively, the SOC may be acquired on the basis of the corrected remaining capacity. Also, as in the first embodiment, the present invention is effective even if the maximum capacity and the value of correction of the SOH of each of the plurality of cells are calculated. 
     As described above with reference to  FIG. 2 , the management device  100  may be implemented by a computer. In this case, a program for implementing each function is recorded on a computer-readable recording medium. Each function may be implemented by causing a computer system to read the program recorded on the recording medium and execute the program using a calculation processing circuit such as a CPU. 
     Also, it is assumed that the “computer system” described here is a computer system embedded in each device and includes an operating system (OS) and hardware such as peripheral devices. Also, the “computer-readable recording medium” refers to a storage device including a flexible disk, a magneto-optical disc, a ROM, a portable medium such as a CD-ROM, a hard disk embedded in the computer system, and the like. 
     The “computer-readable recording medium” may include a computer-readable recording medium for dynamically retaining a program for a short time period as in a communication line when the program is transmitted via a network such as the Internet or a communication circuit such as a telephone circuit. Also, the “computer-readable recording medium” may include a computer-readable recording medium for retaining the program for a certain time period as in a volatile memory inside the computer system including a server and a client when the program is transmitted. 
     The above-described program may be used to implement some of the above-described functions. Also, the program may implement the above-described functions in combination with a program already recorded on the computer system. Also, the above-described computer system may be configured as a computing resource which is a component of a cloud computing system. The cloud computing system makes it possible to mutually transmit and receive various types of data via a network. 
     Also, a part of all of each of the devices may be implemented as an integrated circuit such as a large scale integration (LSI) circuit. Functional blocks of each device may be made into a processor individually or a part or all thereof may be integrated into a processor. Also, a technique of forming an integrated circuit is not limited to an LSI circuit and this may be implemented by a dedicated circuit and/or a general-purpose processor. Also, if technology for an integrated circuit which replaces an LSI circuit emerges with the advancement of semiconductor technology, an integrated circuit based on this technology may be used. 
     [Supplementary Note] 
     (1) According to an aspect of the present invention, there is provided a secondary battery management device, which is communicably connected to a secondary battery unit including a secondary battery and which manages the secondary battery unit, wherein the secondary battery management device is configured to: request the secondary battery unit to transmit a voltage and a state value of the secondary battery; receive the voltage and the state value of the secondary battery transmitted from the secondary battery unit; calculate a value of correction of the state value on the basis of the voltage and the state value which have been received; and transmit the calculated value of correction to the secondary battery unit in order to apply the calculated value of correction. 
     (2) According to another aspect of the present invention, in the secondary battery management device according to the aspect (1), the secondary battery management device is configured to apply the value of correction to the secondary battery at a timing designated for the secondary battery. 
     (3) According to another aspect of the present invention, in the secondary battery management device according to the aspect (1) or (2), the secondary battery management device is configured to: receive the voltage and the state value from each of a plurality of secondary battery units; calculate the value of correction using an algorithm common to the plurality of secondary battery units; and apply the value of correction at a tuning designated for each of the plurality of secondary battery units. 
     (4) According to another aspect of the present invention, in the secondary battery management device according to any one of the aspects (1) to (3), the secondary battery includes a plurality of cells, and the secondary battery management device is configured to: receive the voltage and the state value of each of the plurality of cells; calculate the value of correction of each of the plurality of cells on the basis of the voltage and the state value that have been received; transmit the calculated value of correction to the secondary battery unit; and instruct the secondary battery unit to perform discharging control for each cell. 
     (5) According to another aspect of the present invention, in the secondary battery management device according to any one of the aspects (1) to (4), the state value includes at least one of a charging rate, a remaining capacity, a maximum capacity, or a degree of deterioration of the secondary battery. 
     (6) According to another aspect of the present invention, in the secondary battery management device according to the aspect (1), a relationship between the voltage and the state value of the secondary battery has predetermined characteristics, and the secondary battery management device is configured to calculate the value of correction of the state value using a feature point or a feature section in the predetermined characteristics. 
     (7) According to another aspect of the present invention, in the secondary battery management device according to the aspect (4), the state value is a remaining capacity of the secondary battery, and the secondary battery management device is configured to: compare remaining capacities between the plurality of cells; and control discharging times of some cells having the remaining capacities which are relatively high. 
     (8) According to another aspect of the present invention, there is provided a secondary battery management method performed by a secondary battery management device, which is communicably connected to a secondary battery unit including a secondary battery and which manages the secondary battery unit, the secondary battery management method including: requesting the secondary battery unit to transmit a voltage and a state value of the secondary battery; receiving the voltage and the state value of the secondary battery transmitted from the secondary battery unit; calculating a value of correction of the state value on the basis of the voltage and the state value which have been received; and transmitting the calculated value of correction to the secondary battery unit in order to apply the calculated value of correction. 
     (9) According to another aspect of the present invention, the secondary battery management method according to the aspect (8) further includes: applying the value of correction to the secondary battery at a timing designated for the secondary battery. 
     (10) According to another aspect of the present invention, the secondary battery management method according to the aspect (8) or (9) further includes: receiving the voltage and the state value from each of a plurality of secondary battery units; calculating the value of correction using an algorithm common to the plurality of secondary battery units; and applying the value of correction at a timing designated for each of the plurality of secondary battery units. 
     (11) According to another aspect of the present invention, in the secondary battery management method according to any one of the aspects (8) to (10), the secondary battery includes a plurality of cells, and the secondary battery management method further includes: receiving the voltage and the state value of each of the plurality of cells; calculating the value of correction of each of the plurality of cells on the basis of the voltage and the state value that have been received; transmitting the calculated value of correction to the secondary battery unit; and instructing the secondary battery unit to perform discharging control for each cell. 
     (12) According to another aspect of the present invention, in the secondary battery management method according to any one of the aspects (8) to (11), the state value includes at least one of a charging rate, a remaining capacity, a maximum capacity, or a degree of deterioration of the secondary battery. 
     (13) According to another aspect of the present invention, in the secondary battery management method according to the aspect (8), a relationship between the voltage and the state value of the secondary battery has predetermined characteristics, and the secondary battery management method further includes: calculating the value of correction of the state value using a feature point or a feature section in the predetermined characteristics. 
     (14) According to another aspect of the present invention, in the secondary battery management method according to the aspect (11), the state value is a remaining capacity of the secondary battery, and the secondary battery management method further includes: comparing remaining capacities between the plurality of cells; and controlling discharging times of some cells having the remaining capacities which are relatively high. 
     (15) According to another aspect of the present invention, there is provided a non-transitory computer readable storage medium storing a program executed by a secondary battery management device, which is communicably connected to a secondary battery unit including a secondary battery and which manages the secondary battery unit, the program instructing the secondary battery management device to: request the secondary battery unit to transmit a voltage and a state value of the secondary battery; receive the voltage and the state value of the secondary battery transmitted from the secondary battery unit; calculate a value of correction of the state value on the basis of the voltage and the state value which have been received; and transmit the calculated value of correction to the secondary battery unit in order to apply the calculated value of correction. 
     (16) According to another aspect of the present invention, in the non-transitory computer readable storage medium according to the aspect (15), the program further instructs the secondary battery management device to: apply the value of correction to the secondary battery at a timing designated for the secondary battery. 
     (17) According to another aspect of the present invention, in the non-transitory computer readable storage medium according to the aspect (15) or (16), the program further instructs the secondary battery management device to: receive the voltage and the state value from each of a plurality of secondary battery units; calculate the value of correction using an algorithm common to the plurality of secondary battery units; and apply the value of correction at a timing designated for each of the plurality of secondary battery units. 
     (18) According to another aspect of the present invention, in the non-transitory computer readable storage medium according to any one of the aspects (15) to (17), the secondary battery includes a plurality of cells, and the program further instructs the secondary battery management device to: receive the voltage and the state value of each of the plurality of cells; calculate the value of correction of each of the plurality of cells on the basis of the voltage and the state value that have been received; transmit the calculated value of correction to the secondary battery unit; and instruct the secondary battery unit to perform discharging control for each cell. 
     (19) According to another aspect of the present invention, in the non-transitory computer readable storage medium according to any one of the aspects (15) to (18), the state value includes at least one of a charging rate, a remaining capacity, a maximum capacity, or a degree of deterioration of the secondary battery. 
     (20) According to another aspect of the present invention, in the non-transitory computer readable storage medium according to the aspect (15), a relationship between the voltage and the state value of the secondary battery has predetermined characteristics, and the program further instructs the secondary battery management device to: calculate the value of correction of the state value using a feature point or a feature section in the predetermined characteristics. 
     As used herein, the following directional terms “front, back, above, downward, right, left, vertical, horizontal, below, transverse, row and column” as well as any other similar directional terms refer to those instructions of a device equipped with the present invention. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a device equipped with the present invention. 
     The term “configured” is used to describe a component, unit or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function. 
     Moreover, terms that are expressed as “means-plus function” in the claims should include any structure that can be utilized to carry out the function of that part of the present invention. 
     The term “unit” is used to describe a component, unit or part of a hardware and/or software that is constructed and/or programmed to carry out the desired function. Typical examples of the hardware may include, but are not limited to, a device and a circuit. 
     While preferred embodiments of the present invention have been described and illustrated above, it should be understood that these are examples of the present invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the present invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the claims.