JP2014220236A - Secondary battery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery device useful in a device which has less error in estimated remaining capacity and performs charge and discharge at short intervals.SOLUTION: A secondary battery device comprises a control part 200 which includes: a measurement part 211 for measuring an open circuit voltage of a secondary battery (battery module 111); a table memory 220 including an SOC estimation table in which a value of a first remaining capacity corresponding to an open circuit voltage of the secondary battery at a predetermined temperature is stored and a remaining capacity estimation error table in which an error included in a value of the first remaining capacity corresponding to an open circuit voltage of the secondary battery when charge or discharge of the secondary battery at the predetermined temperature is stopped; a correction part 234 for acquiring a first remaining capacity corresponding an open circuit voltage of the secondary battery by using the SOC estimation table; an estimation error creation part 235 for acquiring an estimated error included in the first remaining capacity by using the remaining capacity estimation error table; and a remaining capacity calculation part 236 for calculating an estimated value of the remaining capacity of the secondary battery from the first remaining capacity and the estimated error.

Description

  Embodiments described herein relate generally to a secondary battery device.

  In a system using a secondary battery, the remaining energy capacity of the secondary battery (hereinafter referred to as “SOC: State Of Charge”) is monitored. The remaining capacity of the secondary battery is monitored, and charging and discharging of the secondary battery are controlled so that the secondary battery can be used effectively.

  Various techniques have been proposed for calculating the remaining capacity of the secondary battery. For example, the current flowing through the secondary battery is obtained by integrating according to a predetermined algorithm. Next, an estimated value of the remaining capacity is calculated from a predetermined relationship between the current integrated value measured in advance and the remaining capacity.

  As another example, the open circuit voltage (OCV) (voltage when no current flows through the secondary battery) of the secondary battery is actually measured, and the remaining capacity is estimated from the open circuit voltage. There is also a method of calculating the value. That is, the relationship between the open circuit voltage and the remaining capacity in the secondary battery can be tabulated based on data measured in advance. By measuring the open circuit voltage of the secondary battery and referring to the table, it is possible to calculate an estimated value of the remaining capacity.

  Although it is possible to calculate an estimated value of the remaining capacity based on the integrated current value, if only the integrated current value is used, there is a possibility that the error of the remaining capacity increases due to a current measurement error. Therefore, a method (OCV correction) for correcting an error in the remaining capacity using an open circuit voltage has been proposed.

  In another example, an estimated value of remaining capacity (= SOC1) calculated based on the integrated current value and an estimated value of remaining capacity (= SOC2) calculated based on the open circuit voltage are obtained. . Then, when SOC2 is compared with SOC2 and the estimated value of the remaining capacity is obtained, the smaller one is adopted as the remaining capacity when the state of the secondary battery is in the charged state, and the larger remaining one is obtained in the discharged state. Adopted as capacity.

JP 2012-58088 A

  There is a certain relationship between the remaining capacity and the open circuit voltage of the secondary battery. For this reason, if the open circuit voltage of a secondary battery is measured, the remaining capacity can be obtained. However, while the secondary battery is repeatedly charged and discharged (hereinafter referred to as charge / discharge), the voltage of the secondary battery deviates from the original open circuit voltage. Therefore, the voltage of the secondary battery immediately after stopping the charge / discharge charge and discharge does not match the original open circuit voltage which is not stable. The voltage of the secondary battery immediately after stopping charging and discharging gradually approaches the open circuit voltage as time passes. In other words, using the voltage of the secondary battery immediately after stopping charging / discharging and performing OCV correction based on the relationship between the open circuit voltage of the secondary battery measured in advance and the remaining capacity, a value different from the actual remaining capacity is obtained. Become.

  In order to increase the calculation accuracy of the estimated value of the remaining capacity, after the charging and discharging of the secondary battery is completed, the voltage is stabilized, and then the open circuit voltage of the secondary battery is measured to correct the OCV. Can be considered. However, the charging or discharging of the secondary battery may be resumed immediately after the charging and discharging are stopped and before the voltage of the secondary battery is stabilized. Alternatively, there is a system that is operated so that charging or discharging of the secondary battery is resumed immediately after the charging or discharging of the secondary battery is stopped and before the voltage of the secondary battery is stabilized. In such a case, the situation where the OCV correction is not performed continues, and the error of the remaining capacity increases.

  An object of the present invention is to provide a secondary battery device capable of calculating an estimated value of the remaining capacity of a secondary battery in a short time.

  The secondary battery device according to the embodiment includes a measurement unit that measures an open circuit voltage of a secondary battery, an SOC estimation table that stores a value of a first remaining capacity with respect to the open circuit voltage of the secondary battery at a predetermined temperature, and A remaining capacity estimation error table storing an error included in the value of the first remaining capacity corresponding to an open circuit voltage of the secondary battery when charging or discharging of the secondary battery at a predetermined temperature is stopped; Including a table memory, a correction unit that acquires a first remaining capacity with respect to an open circuit voltage of the secondary battery using the SOC estimation table, and an estimation included in the first remaining capacity using the remaining capacity estimation error table An estimation error generation unit that acquires an error; and a remaining capacity calculation unit that calculates an estimated value of the remaining capacity of the secondary battery from the first remaining capacity and the estimation error.

FIG. 1 is a diagram illustrating a schematic configuration of a secondary battery device according to an embodiment. FIG. 2 is a flowchart illustrating an operation example of the secondary battery device according to the embodiment of FIG. 1. FIG. 3 is a diagram illustrating an example of an SOC remaining capacity estimation error table used in one embodiment. FIG. 4 is a diagram showing an example of a remaining capacity estimation error table based on the correlation between the battery voltage change rate and the battery temperature immediately after the charging (or discharging) is stopped. FIG. 5 is a flowchart illustrating an operation example of the secondary battery device according to the embodiment of FIG. 4. FIG. 6 is a diagram for describing an example of a method for creating data of a remaining capacity estimation error table used in the secondary battery device according to the embodiment. FIG. 7 is a diagram illustrating an example of the measurement result of the SOC estimation error when creating the SOC remaining capacity estimation error table used in the embodiment. FIG. 8 is a diagram illustrating an example of the relationship of the SOC estimation error with respect to the voltage (OCV) of the secondary battery. FIG. 9 is a diagram for explaining an example of items that can be omitted from the measurement result of the SOC estimation error shown in FIG. FIG. 10 is a diagram illustrating an example of a result of SOC estimation error in a plurality of temperature environments when the SOC remaining capacity estimation error table is created. FIG. 11 is a remaining capacity estimation error table created by thinning out the shaded portion from the SOC estimation error result shown in FIG. FIG. 12 is a diagram showing another example of the remaining capacity estimation error table based on the correlation between the battery voltage change rate and the battery temperature immediately after the charging (or discharging) is stopped. FIG. 13 is a remaining capacity estimation error table created by thinning out predetermined items from the SOC estimation error results shown in FIG.

Hereinafter, embodiments will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a schematic configuration of a secondary battery device according to an embodiment. FIG. 1 shows a battery module 111, a secondary battery device, and a load 300.

  The battery module 111 includes a plurality of secondary batteries C1, C2,... Cn, a positive terminal 101, a negative terminal 102, a current detector 112, and a temperature sensor Ts.

  The plurality of secondary batteries C1, C2,... Cn are, for example, connected in series and housed in a casing in a state in which a series circuit is formed. Each of secondary batteries C1, C2,... Cn may be a single secondary battery cell or a combination of a plurality of secondary battery cells. Although the battery module will be described as a representative here, the present embodiment is applicable to all types of secondary batteries and can be applied to single cell packs. The secondary batteries C1, C2,... Cn are not limited to series connection but may be parallel connection, and may be a combination of series connection and parallel connection.

  The plus terminal 101 and the minus terminal 102 are electrically connected to the load 300. The charging current from the load 300 is supplied to the plurality of secondary batteries C1, C2,... Cn via the plus terminal 101 and the minus terminal 102, and the plurality of secondary batteries C1, according to the energy consumed by the load 300, A discharge current is output from C2,.

  The current detector 112 is inserted in series with a plurality of secondary batteries C1, C2,... Cn in the main circuit on the negative terminal 102 side of the battery module 111. For example, a shunt resistor can be used as the current detector 112.

  At least one temperature sensor Ts is disposed in the vicinity of the plurality of secondary batteries C1, C2,. The temperature sensor Ts may be attached to, for example, a casing (not shown) that houses the plurality of secondary batteries C1, C2,... Cn, or is attached to any of the plurality of secondary batteries C1, C2,. Also good.

  The secondary battery device includes a voltage detector 113, a temperature detector 114, a cell selector 115, a charger / discharger 121, and a control unit 200.

  The voltage detector 113 can detect, for example, the voltages of the positive terminal 101 and the negative terminal 102 of the battery module 111 and the voltages of the positive terminals and the negative terminals of the plurality of secondary batteries C1, C2,. 111 is connected. The voltage detector 113 outputs the detected voltage value to the control unit 200.

  The temperature detector 114 is connected to the temperature sensor Ts and detects at least one temperature in the vicinity of the plurality of secondary batteries C1, C2,... Cn.

  The voltage data measured by the voltage detector 113, the temperature data detected by the temperature detector 114, and the current data detected by the current detector 112 are supplied to the control unit 200, and each value is measured.

  The cell selector 115 switches, for example, the connection between the plurality of secondary batteries C1, C2,... Cn and the voltage detector 113 and the current detector 112.

  The charger / discharger 121 is arranged in the main circuit on the positive terminal 101 side of the battery module 111. The charger / discharger 121 is controlled by the control unit 200, and a state in which the discharge current from the battery module 111 is supplied to the load 300, and a state in which the regenerative current from the load 300 is supplied to the battery module 111 as a charging current. Form.

  The control unit 200 includes a voltage measurement unit 211, a temperature measurement unit 212, a current measurement unit 213, a current value integration unit 214, a charge / discharge control unit 215, a table memory 220, an OCV determination unit 232, and a current value. A tracking unit 233, an OCV correction unit 234, an estimation error generation unit 235, and a remaining capacity calculation unit 236 are provided.

  The voltage measuring device 211 acquires the detection data from the voltage detector 113. The voltage measuring device 211 can measure the output voltage of the battery module 111 and the voltages of the plurality of secondary batteries C1, C2,... Cn from the acquired voltage value. In addition, when the voltage of each cell is measured by the voltage detector 113 and the voltage measuring unit 211, a switch in the battery module 111 is used so that the cell selector 115 can extract and measure the voltage of each cell. (Not shown).

  The temperature measuring device 212 acquires detection data from the temperature detector 114. The temperature measuring device 212 can acquire temperature data in the battery module 111 sensed by the temperature sensor Ts from the temperature detector 114.

  The voltage detector 211 and the temperature detector 212 may be mounted on a separate substrate from the control unit 200, and may be further included in the battery module 111.

  The current measurement unit 213 acquires detection data from the current detector 112. The current detector 112 and the control unit 200 can measure the output current of the series circuit of the secondary batteries C1-Cn. Moreover, the electric current which flows into each secondary battery C1-Cn can also be measured as needed. At this time, the cell selector 115 controls a switch (not shown) in the battery module 111 so that the current of each secondary battery can be taken out and measured. The current value measured by the current measuring unit 213 can be regarded as a charging current or a discharging current.

  The current value integrating unit 214 integrates the current value measured by the current measuring unit 213 in the current value integrating unit 214. The integration result of the current value is used to calculate the SOC.

  The voltage, current and temperature measuring means and measuring method can be variously configured, and are not limited to the configurations described here.

  The charge / discharge control unit 215 can control the charger / discharger 121 connected to the positive terminal 101 side. When the charger / discharger 121 is controlled, a state in which the discharge current from the battery module 111 is supplied to the load 300 or a state in which the regenerative current from the load 300 is supplied to the battery module 111 as a charging current is formed. can do. The battery module 111 may be charged by a dedicated charging device.

  In addition, the control unit 200 can detect the voltages of the individual secondary batteries and perform equalization processing so that the voltages of the individual secondary batteries become equal.

  The table memory 220 stores data of various tables (an SOC estimation table, a remaining capacity estimation error table, etc.). The table memory 220 is a writable memory, and data such as a remaining capacity estimation error table described later can be rewritten as necessary. When battery performance, device specifications, standards, etc. are changed and data adjustment is required, the data stored in the table memory 220 is rewritten. The data change or rewrite work includes a method of exchanging a chip of the memory itself or a method of rewriting from the outside via a communication line.

  The deterioration estimation unit 231 determines the deterioration state of the secondary battery from the battery deterioration information such as use history, use environment, use years, charge / discharge characteristics. Here, the deterioration state of the secondary battery is, for example, information on the battery capacity [%] that has decreased with respect to the shipping time of the secondary battery or the internal resistance [%] that has increased with respect to the shipping time of the secondary battery.

  The OCV determination unit 232 obtains a current measurement result from the current measurement unit 213, and when the current measurement result is equal to or less than a certain value, the voltage measurement result in the voltage measurement unit 211 is regarded as OCV and transmits the voltage value to the OCV correction unit 234. When the control unit 200 does not have a current measurement function, the OCV determination unit 232 always regards the voltage measurement result in the voltage measurement unit 211 as OCV, and transmits the voltage measurement result to the OCV correction unit 234.

  The current value tracking unit 233 tracks the current value detected by the current measuring unit 213 and monitors a change in current for each predetermined period. The current value tracking unit 233 may be referred to as a current direction detection unit. The current tracking unit 233 can measure and record the magnitude of the current immediately before the charging current and the discharging current are stopped and the direction of the current (whether the charging state or the discharging state), and can store it for a certain period.

  The OCV correction unit 234 corrects the SOC using the measurement result (OCV) of the OCV determination unit 232. The OCV correction unit 234 may be referred to as a first correction unit. The SOC obtained at this time may be referred to as a first remaining capacity (SOC_C).

  The first remaining capacity (SOC_C) is generated using data of an SOC estimation table prepared and prepared in advance. The SOC estimation table has data obtained by measuring the correlation between the OCV and the SOC of the secondary battery under a plurality of temperature environments. That is, this is an SOC estimation table in which the SOC corresponding to the change in the OCV of the secondary battery is measured in advance, and the SOC can be estimated by measuring the OCV. Since the relationship between the OCV and SOC of the secondary battery varies depending on the battery temperature, an SOC estimation table is prepared for each of a plurality of battery temperatures. Furthermore, the secondary battery may also be deteriorated depending on the deterioration state of the secondary battery (for example, the battery capacity [%] decreased with respect to the shipping time of the secondary battery or the internal resistance [%] increased with respect to the shipping time of the secondary battery). The relationship between OCV and SOC changes. For this purpose, an SOC estimation table and a remaining capacity estimation error table used according to the deterioration state are prepared. There are various methods for determining the deterioration state, and the deterioration state may be determined from information such as battery usage time and charge / discharge characteristics of the secondary battery. Also, the SOC variation characteristic varies depending on the type of secondary battery used, and an SOC estimation table corresponding to the type of secondary battery used is used.

  The estimation error generation unit 235 generates a remaining capacity estimation error (SOC_E). Based on the measured OCV, the measured temperature, and the current at the time of measurement (current direction), the estimation error generation unit 235 performs an estimation error by calculation using data of a remaining capacity estimation error table prepared in advance. (SOC_E) is generated. This estimation error (SOC_E) is data (error) used to adjust the previously estimated first remaining capacity (SOC_C).

The remaining capacity calculation unit 236 executes, for example, the following calculation.
SOC = first remaining capacity (SOC_C) + estimation error (SOC_E)
The secondary battery device of the present embodiment outputs the SOC obtained by this calculation as the final estimated remaining capacity (SOC). This estimated value (SOC) of the remaining capacity is used as a notification element for displaying the SOC state. The notification of the remaining amount estimation value (SOC) may be used as information for determining the number of times charging or discharging has been performed.

  The example of FIG. 1 shows one set of the control unit 200, the battery module 111, the current detector 112, the voltage detector 113, the temperature detector 114, and the cell selector 115, but there are a plurality of these blocks. Thus, a battery pack may be formed. In some cases, this device only instructs charging and discharging and does not have a charger / discharger. In other words, a charger / discharger may be provided separately.

FIG. 2 is a flowchart illustrating an operation example of the secondary battery device according to the embodiment of FIG. 1.
The control unit 200 can execute a program described by a plurality of codes. The control unit 200 may be referred to as an arithmetic device, an arithmetic unit, a processor, or the like. Each operation block may be referred to as a module, a unit, or the like. Each block in the control unit 200 can be realized by a code (or an instruction) that executes software.

  The operation until the control unit 200 obtains the final estimated remaining capacity (SOC) will be described with reference to FIG.

  In step SA1, the control unit 200 measures and records the current magnitude and current direction immediately before the charging or discharging of the battery module 111 stops. That is, the control unit 200 controls the charger / discharger 121 by the charge / discharge control unit 215 and measures the current flowing through the battery module 111 by the current measurement unit 213 before stopping the charging or discharging, The direction (charging or discharging) is recorded in the current value tracking unit 233. Thereafter, charging or discharging of the battery module 111 is stopped by the charge / discharge control unit 215.

  In the next step SA2, the control unit 200 measures the battery voltage (OCV) immediately after the charging or discharging is stopped by the OCV determination unit 232, and measures the battery temperature (T) by the temperature measuring unit 212. The OCV determination unit 232 and the temperature measurement unit 212 store the measured values in a memory (not shown), for example.

  In the next step SA3, the control unit 200 is controlled by the OCV correction unit 234, and the control unit 200 is based on the measured battery voltage (OCV), battery temperature (T), and current (current direction) at the time of measurement. The first remaining capacity (SOC_C) is acquired using data of the SOC estimation table created in advance.

  In the next step SA4, the control unit 200 uses the estimation error generation unit 235 to calculate the remaining capacity estimation error prepared and prepared in advance based on the measured battery voltage (OCV), battery temperature (T), and current. An estimation error (SOC_E) is generated using the data in the table.

  The remaining capacity estimation error table data is data for correcting an error included in the first remaining capacity SOC_C acquired in step SA3. The reason for using this remaining capacity estimation error table is as follows. There is a certain relationship between the voltage (OCV) and the remaining capacity (SOC). For this reason, if the voltage (OCV) of a secondary battery is measured, the remaining capacity (SOC) can be estimated.

  However, while the secondary battery is repeatedly charged and discharged, the voltage of the secondary battery deviates from the original voltage. That is, the voltage of the secondary battery is different when charging and discharging are performed and when time is elapsed after stopping charging and discharging. Therefore, when charging and discharging are stopped (or a voltage immediately after stopping), the original voltage when the voltage of the secondary battery is stable does not match. When charging and discharging are stopped (or voltage immediately after stopping), the voltage gradually approaches the original voltage as time passes.

In other words, when the OCV correction for the SOC is performed using the open circuit voltage (OCV) when charging and discharging are stopped (immediately after the stop), the remaining capacity estimated using the SOC estimation table as described above ( SOC_C) is a value including an error, and is different from the actual remaining capacity of the secondary battery.
Therefore, in the present embodiment, the estimation error (SOC_E) included in the first remaining capacity (SOC_C) estimated in step SA3 is generated using the remaining capacity estimation error table.

FIG. 3 is a diagram showing an example of an SOC remaining capacity estimation error table used in the present embodiment.
The remaining capacity estimation error table of FIG. 3 shows the remaining capacity error when the battery module 111 is charged with the current (1C). For example, when the temperature is 25 ° C. and the measured voltage (OCV) immediately after the charging is stopped is 3 V, for example, the estimation error (SOC_E) included in the first remaining capacity (SOC_C) is −45%. It shows that there is. When the temperature is 25 ° C., the measured voltage (OCV) immediately after the charging is stopped is 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V. The obtained errors (SOC_E) are −43%, −43%, −42%, −42%, −41%, −41%, and −40%, respectively.

  Similarly, when the battery temperature is 0 ° C., an error in each voltage in the case of 55 ° C. is measured and prepared in advance. This remaining capacity estimation error table is an example, and actually, a plurality of remaining capacity estimation error tables are prepared according to the magnitude of the charging current (or discharging current).

  When the remaining capacity estimation error table as described above exists, an estimated value of the remaining capacity can be obtained by calculation based on the SOC estimation error corresponding to the measured battery temperature and voltage.

That is, in step SA5, the control unit 200 uses the remaining capacity calculation unit 236 to calculate an estimated value of the remaining capacity as follows.
Estimated value of remaining capacity (SOC) = first remaining capacity (SOC_C) + estimation error (SOC_E)
Here, not all the errors corresponding to the actually measured battery temperature and voltage are prepared in the remaining capacity estimation error table prepared in advance. In such a case, an error is calculated by an approximate expression using the data of the remaining capacity estimation error table close to the measured battery temperature and voltage.

  The present invention is not limited to the above-described embodiment. In the apparatus of the present invention, an error table for estimating the remaining capacity is prepared so that it is not necessary to spend time from immediately after charging and discharging until the battery voltage (OCV) is stabilized. In the remaining capacity estimation error table of the previous embodiment, an error based on the correlation between the battery voltage and the battery temperature is stored as a percentage.

  However, not only the correlation between the battery voltage and the battery temperature, but also an error can be created based on the correlation between the battery voltage change rate dV and the battery temperature immediately after the charging and discharging are stopped. In order to obtain the change rate dV of the battery voltage immediately after the charging and discharging are stopped, at least two voltage measurements are necessary, but there is no need to wait until the OCV is stabilized.

  Therefore, in the second embodiment described below, if the correlation between the battery voltage change rate dV and the battery temperature immediately after the charging and discharging are stopped is known, it can be obtained when waiting until the OCV stabilizes. We focus on the ability to predict SOC errors.

  FIG. 4 is a diagram showing an example of a remaining capacity estimation error table based on the correlation between the battery voltage change rate dV and the battery temperature immediately after the charging / discharging is stopped.

  This table shows that an error of −31% exists in the first remaining capacity (SOC_C) when the voltage change rate dV is, for example, 0.5% under an environment of 25 ° C. Furthermore, when the voltage change rate dV is 0.9%, 1.3%, 1.7%, 2.1%, 2.5%, 2.9%, 3.3%, -32%,- It shows that there are errors of 34%, -35%, -47%, -47%, -49%, and 45%.

  Although one table is shown here, a plurality of remaining capacity estimation error tables are prepared according to the difference in battery temperature. If the measured voltage change rate / battery temperature value is not found in multiple tables, the voltage change rate / battery temperature value close to the measured voltage change rate / battery temperature value is The remaining amount estimation error data is calculated by an approximate expression.

  Furthermore, when the measured voltage change rate value is less than the minimum value of the voltage change rate stored in the remaining capacity estimation error table, it can be considered that the voltage change is minute (almost no). In this case, error correction is not performed, and the first remaining capacity (SOC_C) obtained by the measured OCV is directly adopted as the SOC subjected to OCV correction.

  Furthermore, when the measured voltage change rate value is larger than the maximum value stored in the remaining capacity estimation error table, the OCV correction error is considered to be large. In this case, OCV correction is not performed, and the previous SOC (current integrated value before OCV correction) is maintained.

  That is, when the voltage change rate obtained from the change of the open circuit voltage is below a certain value, the first remaining capacity obtained by the open circuit voltage immediately after the stop of charging or discharging of the secondary battery is adopted as the estimated value of the remaining capacity. To do. On the other hand, when the voltage change rate obtained from the change in the open circuit voltage is a certain value or more, the error correction of the first remaining capacity (SOC_C) is not performed. As will be described later, when the control unit 200 does not have a current measurement function, the remaining capacity obtained by the previous OCV correction is used.

  FIG. 5 is a flowchart shown for explaining the operation until the control unit 200 obtains the estimated value (SOC) of the remaining capacity.

First, the control unit 200 periodically measures and records the battery voltage (OCV) and the battery temperature immediately after the charging and discharging are stopped by the temperature measurement unit 212 and the OCV determination unit 232. (Step SB1)
Next, based on the measured battery voltage (OCV) and temperature, the control unit 200 uses the corresponding SOC estimation table stored in the table memory 220 to calculate the first remaining capacity (SOC_C) by the OCV correction unit 234. get. (Step SB2)
Subsequently, the control unit 200 uses the voltage measuring unit 211 to calculate the battery voltage change rate dV using the plurality of battery voltages (OCV) measured in step SB1. (Step SB3)
Next, based on the battery voltage change rate dV and the value of the battery temperature obtained by the estimation error generation unit 235, the control unit 200 corresponds to the corresponding remaining capacity estimation error table stored in the table memory 220. Select capacity estimation error data. Further, the estimation error generation unit 235 calculates an estimation error (SOC_E) using the selected remaining capacity estimation error data. (Step SB4)
In the next step SB5, the control unit 200 uses the remaining capacity calculation unit 236 to
The estimated value (SOC) of the remaining capacity can be obtained by calculating the estimated value (SOC) of the remaining capacity = the first remaining capacity (SOC_C) + the estimation error (SOC_E).

In the case of the second embodiment described above, the estimated value (SOC) of the remaining capacity can be obtained even when the control unit 200 does not have a current measurement function.
Instead, a calculation unit for calculating the voltage change rate dV is required. However, the calculation of the voltage change rate dV can be easily handled by a slight change in the processing program of the voltage measuring unit 211.

  In the above-described apparatus according to the present embodiment, the first remaining capacity SOC_C can be obtained using the OCV immediately after charging and immediately after discharging. Therefore, the open circuit voltage OCV is used to calculate the estimated value (SOC) of the remaining capacity. Does not require time to stabilize. For this reason, the estimated value SOC of the remaining capacity can be obtained early.

  That is, according to the secondary battery device of the present embodiment, the remaining capacity can be corrected before the voltage of the secondary battery is stabilized after the charge / discharge is stopped. It is possible to provide a secondary battery device that can be used effectively even when the device has a small capacity error, charging / discharging is performed at short intervals, and charging / discharging is short from start to stop.

  Further, according to the apparatus of the above embodiment, if the SOC value in which the error is calculated in advance is prepared in the tables shown in FIG. 3 and FIG. 4 and this value is directly used, the final remaining capacity is calculated. The estimation value (SOC) can be easily acquired. That is, the control unit 200 can omit the steps of calculating the first remaining capacity SOC_C and further calculating the remaining capacity error.

  It goes without saying that each block in the control unit 220 can be realized by a code (or an instruction) for executing software.

  Therefore, in this case, the program is installed in a control unit that monitors charging and discharging performed on the secondary battery and the temperature of the secondary battery. This program is created in advance based on the instruction for obtaining the first remaining capacity based on the open circuit voltage when the charging or discharging of the secondary battery is stopped, the estimated remaining battery capacity, and the open circuit voltage and temperature. And an instruction for obtaining an estimation error of the first remaining capacity using the error data of the remaining capacity estimation error table. Furthermore, the first remaining capacity is corrected with the estimation error, and the instruction for determining the estimated remaining capacity of the secondary battery is included.

  Next, an example regarding the creation of the remaining capacity estimation error table will be described. The remaining capacity estimation error table is collected by measuring the battery voltage under various temperature environments by changing the values of the charging current and discharging current (by various charging / discharging patterns).

For example, the following conditions are set as measurement conditions.
Environmental temperature, for example, 0 ° C, 25 ° C, 55 ° C
As current values, 1C is charged and -1C is discharged.
For example, when it is desired to collect data when charging is performed, the following procedure is taken.
(A1) Completely discharge the selected battery at room temperature. (B1) Next, the following evaluation is performed when the battery is charged to 100% in units of 10% of SOC, for example.
For example, the battery is charged with 10% of SOC based on the integrated current value, and then rests for 1 hour. For example, when the capacity of the battery is 100 Ah, the battery capacity for 10% is 10 Ah, so charging is performed at 10 A for 1 hour, and then charging and discharging are suspended for 1 hour.

  Here, in order to obtain evaluation data, a change in voltage after charging is measured to obtain a voltage change pattern.

(A2) Next, the selected battery is completely discharged at room temperature. (B2) Next, for example, the battery is charged with 20% of SOC based on the integrated current value, and then rests for 1 hour.
Here, in order to obtain evaluation data, a change in voltage after charging is measured to obtain a voltage change pattern.

(A3) Next, the selected battery is completely discharged at room temperature. (B3) Next, for example, the battery is charged with 30% of SOC based on the integrated current value, and then rests for 1 hour.
Here, in order to obtain evaluation data, a change in voltage after charging is measured to obtain a voltage change pattern.

  As described above, evaluation data can be collected by repeating measurement of the voltage change pattern after charging for each charging percentage.

  FIG. 6 is a diagram for describing an example of a method for creating data of a remaining capacity estimation error table used in the secondary battery device according to the embodiment. 6 (A), 6 (B) and 6 (C) are samples when a voltage change pattern is obtained after charging with SOC 50%, SOC 65% and SOC 85% at an environmental temperature of 25 ° C., for example. Is shown. In addition, the sample of the voltage change pattern shown here has shown the result of having measured the change of the open circuit voltage of a secondary battery in time series, making the time of stopping charging 0 seconds.

  In such a sample, for example, when the battery is charged with an SOC of 65% based on the integrated current value at an environmental temperature of 25 ° C., a voltage change pattern after charging is examined. In this voltage change pattern, the open circuit voltage became 2.7 V after 30 seconds from charging. On the other hand, the SOC calculation result when OCV correction was performed for this measured voltage of 2.7 V was 75.5%.

In other words, if OCV correction is simply performed, this means that an error of 15.5% occurs.
Therefore, it can be seen that the OCV-corrected first remaining capacity (SOC_C) is + 15.5% larger than the SOC that should be originally obtained. Therefore, 15.5% is described in the remaining capacity estimation error table as the estimation error (SOC_E).

  For other various estimation errors, data for correcting the error can be constructed from the voltage change pattern of each case in the same manner as described above. Further, not only when the ambient temperature is 25 ° C. but also when there are a plurality of temperatures, data for correcting an error can be constructed from the voltage change pattern of each case in the same manner as described above.

When the data of the remaining capacity estimation error table of FIG. 4 showing the correlation between the voltage change rate and the temperature is constructed, it is constructed as follows.
That is, the rate of change is calculated by comparing the voltage (OCV) based on the data of the SOC estimation table prepared in advance with the measured voltage after charging or discharging in the voltage pattern. This rate of change depends on the voltage (OCV) corresponding to each SOC percentage (for example, SOC 60%, SOC 70%, SOC 80%) and actually charge or discharge to SOC 60%, SOC 70%, SOC 80% for each temperature. And the measured voltage measured after.

  For example, the voltage change rate dV when charging to SOC 70% at a predetermined environmental temperature is stable over time after the open circuit voltage measured immediately after charging and SOC 70% at a predetermined environmental temperature. Calculated by the difference from the open circuit voltage (obtained from the SOC estimation table).

  For example, the voltage values that are the items in the column of the remaining capacity estimation error table shown in FIG. 3 are defined at equal intervals in units of 0.1 V, but this need not be particular about equal intervals. Further, it is not necessary to limit the temperature to 0, 25, and 55 ° C.

  In the above embodiment, when the remaining capacity estimation error table shown in FIG. 3 is created, data is collected by measuring the battery voltage under the following conditions.

Environmental temperature, for example, 0 ° C, 25 ° C, 55 ° C
As current values, 1C is charged and -1C is discharged.
For example, when it is desired to collect data when charging is performed, the following procedure is taken.
(A1) Completely discharge the selected battery at room temperature. (B1) Next, the following evaluation is performed when the battery is charged to 100% in units of 10% of SOC, for example.
For example, the battery is charged with 10% of (?) SOC based on the integrated current value, and then rests for 1 hour.
FIG. 7 is a diagram illustrating an example of the measurement result of the SOC estimation error when creating the SOC remaining capacity estimation error table used in the embodiment.
The battery voltage measurement conditions may be changed, for example, as follows.

The environmental temperature is -30 to 70 ° C in increments of 5 ° C.
The current value is charged at a value of 0.5C between 0.1C, 0.3C, 0.5C and 10C, and between -0.1C, -0.3C, -0.5C and -10C. Discharge at 0.5C intervals.

For example, when it is desired to collect data when charging is performed, the following procedure is taken.
(A1) Completely discharge the selected battery at room temperature, (b1) Next, charge the battery to 100% in units of 5% of SOC, for example, and measure the battery voltage as in the above embodiment I do.

  As described above, the temperature, current value, and charge / discharge pattern are set more finely. The SOC is obtained by OCV correction at a voltage n seconds after the end of charging, and is obtained by OCV correction when sufficient time has elapsed from the end of charging. If the difference from the calculated SOC (obtained from the SOC estimation table) tends to be constant with respect to the temperature / current / setting change, the calculated SOC difference can be estimated from the previous and subsequent values. It is not necessary to define the values of the row (temperature) and the column (voltage) at regular intervals as in the table shown in FIG.

FIG. 8 is a diagram illustrating an example of the relationship of the SOC estimation error with respect to the voltage (OCV) of the secondary battery.
For example, the case where the result shown in FIG. 8 is obtained as an evaluation result at a certain temperature will be described. In the graph shown in FIG. 8, the tendency of change varies with voltages of 2.5 to 3.1 V, 3.1 to 3.4 V, 3.4 to 3.5 V, and 3.5 to 4.3 V. In other words, if the values at both ends and the change rate of the SOC estimation error in each range are known within each range, the change rate included in the range can be calculated by an approximate expression. Therefore, as a table, it is sufficient to prepare SOCs corresponding to five points of 2.5, 3.1, 3.4, 3.5, and 4.3 V as a column.

FIG. 9 is a diagram for explaining an example of items that can be omitted from the measurement result of the SOC estimation error shown in FIG.
That is, the SOC estimation error of the shaded portion in FIG. 9 can be estimated from the values before and after that, and can be omitted from the table. For example, the SOC estimation error in the case of 2.7 V can be easily estimated as follows by linear approximation from the values (2.5, 20) and (3.1, 8) in the tables before and after that. .
{(−20 − (− 8)) / (2.5−3.1)} * (2.7−2.5) + (− 20) = 20 * 0.2 + (− 20) = 4 + (− 20) = − 16
Note that although linear approximation is used here, polynomial approximation may be used. When polynomial approximation is performed, values before and after the omitted value and a polynomial to be applied to the omitted range are required.

  The examples shown in FIGS. 7 to 9 summarize the evaluation for a predetermined temperature, but the same evaluation is performed when the temperature is changed or the charge / discharge rate is changed. The table can be thinned out according to the trend of the results.

  FIG. 10 is a diagram illustrating an example of a result of SOC estimation error in a plurality of temperature environments when the SOC remaining capacity estimation error table is created.

  For example, assuming that the example shown in FIGS. 7 to 9 is an environment temperature of 25 ° C., it is assumed that the SOC estimation error [%] shown in FIG. 10 is obtained by evaluating other temperatures. Although the voltage when evaluated at each temperature is the same, even if the voltage becomes different, the method of creating the remaining capacity estimation error table is not affected.

  At this time, for example, since the SOC estimation error at 20 ° C. can be estimated from the cases of 25 ° C. and 15 ° C. at each voltage, the 20 ° C. row can be deleted from the remaining capacity estimation error table.

FIG. 11 is a remaining capacity estimation error table created by thinning out the shaded portion from the SOC estimation error result shown in FIG.
For example, when the environmental temperature is 20 ° C. and the battery voltage is 3.4 V, the SOC estimation error can be calculated as follows.
{(−8 − (− 5)) / (15−25)} * (20−15) + (− 8) = 0.3 * 5 + (− 8) = 1.5 + (− 8) = − 6. 5
In the example shown in FIG. 10, the battery voltage of the portion that can be thinned (shaded portion) is different between 15 ° C. and 25 ° C. As a method for creating the remaining capacity estimation error table at this time, priority may be given to the simplicity of the battery control method, and only portions that can be thinned out simultaneously may be thinned out.

  For example, when calculating the estimated value of the remaining capacity of the secondary battery using the remaining capacity estimation error table shown in FIG. 11, the remaining temperature estimation error table is referred to in step SA4 of the flowchart shown in FIG. When there is no value corresponding to the battery voltage in the remaining capacity estimation error table, an estimation error (SOC_E) is calculated using an approximate expression. In this case, the estimated value of SOC can be calculated in step SA5 using the value of the calculated estimation error (SOC_E).

  For example, as the number of items in the table increases, the capacity of the table memory 220 increases. Therefore, by reducing the items of the remaining capacity estimation error table as described above, the capacity of the table memory 220 can be reduced and the price of the battery control device can be reduced.

  Although not described in the above configuration, the calculated estimated SOC value may be notified to the outside of the battery control device (for example, the host device) via the communication IF 238, and is satisfied by the calculated estimated SOC value. Discharge permission / stop control may be performed, or a combination thereof may be used.

  CAN, RS485, PLC (Power Line Communication), etc. are applicable as a communication system via communication IF. In this case, the estimated value of the SOC itself is notified to the host device.

  As a charge / discharge control method, for example, when the estimated value of SOC becomes larger than the reference value or becomes smaller than the reference value, the battery is disconnected from the main circuit by opening a breaker such as a relay, contactor, MCCB, etc. There is a method.

FIG. 12 is a diagram showing another example of the remaining capacity estimation error table based on the correlation between the battery voltage change rate and the battery temperature immediately after the charging (or discharging) is stopped.
FIG. 13 is a remaining capacity estimation error table created by thinning out predetermined items from the SOC estimation error results shown in FIG.

  The remaining capacity estimation error table used in the second embodiment can also be reduced in size, for example, similarly to the table shown in FIG. That is, in the remaining capacity estimation error table used in the second embodiment, the voltage change rate is a constant interval as shown in FIG. 4, but the voltage change rate and the temperature interval may be set finely.

  In the example shown in FIG. 12, for example, the change in the estimation error of the SOC with a voltage change rate of 0.3% or more and 0.6% or less is constant, so that table items can be thinned out like the table shown in FIG. I can do it. Note that items can be thinned out similarly to the table shown in FIG. 11 for the temperature and the charge / discharge rate.

  In the example shown in FIG. 11 and FIG. 13, the table is created by thinning out a part of the remaining capacity estimation error table created in advance, but when the range that can be thinned out is known in advance due to the characteristics of the secondary battery, A remaining capacity estimation error table may be created without calculating an estimation error for the thinning range.

  Various secondary batteries such as a lithium ion battery and a nickel metal hydride battery have been developed as secondary batteries to which the present embodiment is applied, and any battery can be used. In addition, in the case of a characteristic in which the change in the OCV follows the change in the SOC, the SOC can be estimated from the OCV with relatively high accuracy.

  Examples of materials such as the negative electrode, the positive electrode, and the electrolyte of the secondary battery are shown below.

1) Negative electrode: The negative electrode has a negative electrode current collector and a negative electrode active material-containing layer. The negative electrode active material-containing layer includes a negative electrode active material, a conductive agent, and a binder. A metal foil such as an aluminum alloy foil can be used for the negative electrode current collector. Examples of the aluminum alloy include, in addition to aluminum, an Al—Fe alloy, an Al—Mn alloy, and an Al—Mg alloy.

  As the negative electrode active material, a material that occludes and releases lithium can be used. Among them, metal oxides, metal sulfides, metal nitrides, alloys, and the like can be given. The lithium occlusion potential of the negative electrode active material is preferably 0.4 V or more in terms of open circuit potential relative to the open circuit potential of lithium metal. Thereby, the progress of the alloying reaction between the aluminum component of the negative electrode current collector and lithium and the pulverization of the negative electrode current collector can be suppressed. Furthermore, the lithium occlusion potential is preferably in the range of 0.4 V or more and 3 V or less in terms of open circuit potential with respect to the open circuit potential of lithium metal. Thereby, a battery voltage can be improved. A more preferable potential range is 0.4 V or more and 2 V or less. Examples of the metal oxide capable of occluding lithium in the range of 0.4 V or more and 3 V or less include titanium oxide, such as lithium titanium oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, and silicon oxide. Etc. Among these, lithium titanium oxide is preferable.

  Examples of the metal sulfide that can occlude lithium in the range of 0.4 V or more and 3 V or less include lithium sulfide, molybdenum sulfide, iron sulfide, and the like.

  Examples of the metal nitride capable of occluding lithium in the range of 0.4 V or more and 3 V or less include lithium cobalt nitride.

  A carbon material can be used as the conductive agent. Examples thereof include acetylene black, carbon black, coke, carbon fiber, and graphite.

  2) Positive electrode: The positive electrode has a positive electrode current collector and a positive electrode active material-containing layer. The positive electrode active material-containing layer is supported on one surface or both surfaces of the positive electrode current collector 19a and includes a positive electrode active material, a conductive agent, and a binder.

  A metal foil such as an aluminum alloy foil can be used for the positive electrode current collector. Examples of the positive electrode active material include oxides, sulfides, and polymers.

  Examples of oxides include manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, and lithium manganese cobalt composite. Examples thereof include oxides, spinel-type lithium manganese nickel composite oxides, lithium phosphorus oxides having an olipine structure, iron sulfate, and vanadium oxides.

  Examples of the polymer include conductive polymer materials such as polyaniline and polypyrrole, and disulfide polymer materials. In addition, sulfur (S), carbon fluoride, and the like can be used.

  As a preferable positive electrode active material, since a high positive electrode voltage can be obtained, lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, spinel type lithium manganese nickel composite oxide, lithium Examples thereof include manganese cobalt composite oxide and lithium iron phosphate.

  Examples of the conductive agent for increasing the electron conductivity and suppressing the contact resistance with the current collector include acetylene black, carbon black, and graphite.

  3) Electrolytic solution: The electrolytic solution is prepared by dissolving an electrolyte in an organic solvent. The electrolyte concentration can be in the range of 0.5 to 2 mol / L.

  An example of the electrolyte is LiBF4. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC), chains such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), and diethyl carbonate (DEC). Carbonates, cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), chain ethers such as dimethoxyethane (DME), γ-butyrolactone (BL), acetonitrile (AN), sulfolane (SL), phosphate esters Etc. These organic solvents can be used alone or in the form of a mixture of two or more.

  In the above description, the terms “unit” and “unit” in terms of detector, control unit, and the like are within the scope of the present invention even if they are replaced with “device”, “block”, “module”, “calculation means”, and the like. Of course. Furthermore, in each constituent element of the claims, even when the constituent element is expressed in a divided manner, when a plurality of constituent elements are expressed together, or when they are expressed in combination, they are within the scope of the present invention. Even when the claims are expressed as a method, the apparatus of the present invention is applied.

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 111 ... Battery module, 112 ... Current detector, 113 ... Voltage detector, 114 ... Temperature detector, 115 ... Cell selector, 121 ... Charge / discharge device, 200 ..Control unit 211 ... Voltage measurement unit 212 ... Temperature measurement unit 213 ... Current measurement unit 214 ... Current value integration unit 232 ... OCV determination unit 233 ... Current value tracking unit, 234 ... SOC correction unit, 236 ... remaining capacity calculation unit, 220 ... table memory, 300 ... load.

Claims (10)

A measurement unit for measuring the open circuit voltage of the secondary battery;
An SOC estimation table storing a value of a first remaining capacity with respect to an open circuit voltage of the secondary battery at a predetermined temperature, and an open circuit of the secondary battery when charging or discharging of the secondary battery at the predetermined temperature is stopped A table memory including a remaining capacity estimation error table that stores an error included in the value of the first remaining capacity corresponding to the voltage;
A correction unit that obtains a first remaining capacity with respect to an open circuit voltage of the secondary battery using the SOC estimation table;
An estimation error generating unit that acquires an estimation error included in the first remaining capacity using the remaining capacity estimation error table;
A secondary battery device comprising: a remaining capacity calculation unit that calculates an estimated value of the remaining capacity of the secondary battery from the first remaining capacity and the estimation error.   The secondary battery device according to claim 1, wherein the remaining capacity estimation error table is created in advance based on the open circuit voltage, the temperature, and the current.   The secondary battery device according to claim 1, wherein the remaining capacity estimation error table is created in advance based on the open circuit voltage, the temperature, and a deterioration state of the secondary battery.   The secondary battery device according to claim 1, wherein the remaining capacity estimation error table is created in advance based on the open circuit voltage, the temperature, the current, and a deterioration state of the secondary battery. The error data of the remaining capacity estimation error table created in advance is the battery voltage immediately after stopping charging of the secondary battery or immediately after stopping discharging of the secondary battery under a certain temperature environment, and the secondary battery It is error data obtained from the battery voltage measured after a certain period of time immediately after stopping charging of the battery or immediately after stopping discharging of the secondary battery,
The secondary battery device according to claim 1. A measurement unit for measuring the open circuit voltage of the secondary battery;
An SOC estimation table storing a value of a first remaining capacity with respect to an open circuit voltage of the secondary battery, and an open circuit voltage of the secondary battery until a predetermined time elapses after charging or discharging of the secondary battery is stopped. A remaining capacity estimation error table that stores an error included in the value of the first remaining capacity corresponding to at least the rate of change of
Using the SOC estimation table, a correction unit that acquires a first remaining capacity with respect to the predetermined temperature and an open circuit voltage of the secondary battery;
Using the remaining capacity estimation error table, an estimation error generating unit that acquires an estimation error included in the first remaining capacity corresponding to a change rate of the open circuit voltage of the predetermined temperature and the secondary battery;
A secondary battery device comprising: a remaining capacity calculation unit that calculates an estimated value of the remaining capacity of the secondary battery from the first remaining capacity and the estimation error.   The secondary battery device according to any one of claims 1 to 6, wherein the remaining capacity estimation error table includes a plurality of remaining capacity estimation error tables obtained under a plurality of temperature environments.   The secondary battery device according to claim 6, wherein when the voltage change rate obtained from the change in the open circuit voltage is equal to or greater than a predetermined value, the first estimated capacity is set as an estimated value of the remaining capacity of the secondary battery.   The secondary battery according to claim 6, wherein when the voltage change rate obtained from the change of the open circuit voltage is equal to or less than a predetermined value, the integrated value of the charging current and discharging current of the secondary battery is set as the remaining capacity of the secondary battery. Battery device.   The estimated error generating unit refers to the remaining capacity estimated error table, and when there is no value corresponding to the predetermined temperature and the open circuit voltage of the secondary battery, the error of the first estimated capacity is calculated using an approximate expression. The secondary battery device according to claim 1, wherein the value of is calculated.

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