WO2013146248A1

WO2013146248A1 - Soc estimation device

Info

Publication number: WO2013146248A1
Application number: PCT/JP2013/056942
Authority: WO
Inventors: 尚人右田; 智哉寺内; 晶彦山田
Original assignee: 三洋電機株式会社
Priority date: 2012-03-26
Filing date: 2013-03-13
Publication date: 2013-10-03

Abstract

[Problem] To improve the estimation accuracy not only in the vicinity of 0% and 100% of the SOC but also over the entire range of the SOC. [Solution] A second calculation unit (83) acquires the target values of targeted charge electricity quantity and SOC from among the target values of a charge electricity quantity and the SOC calculated by a first calculation unit (82). Further, the second calculation unit (83) calculates an integrating factor from the ratio between the quantity of a difference between the target value of the targeted charge electricity quantity and a charge electricity quantity calculated at the last time before a time (T1), and the quantity of a difference between the target value of the targeted SOC and the SOC calculated at the last time before the time (T1). An SOC estimation unit (84) calculates the SOC by a current integration method using the integrating factor acquired from the second calculation unit.

Description

SOC estimation device

The present invention relates to an SOC estimation device for a storage battery.

When using a device using a storage battery, the storage battery can be used efficiently by performing charge / discharge control based on the remaining capacity of the storage battery (hereinafter referred to as SOC: State of Charge). Therefore, it is necessary to accurately estimate the SOC. As a method for calculating the SOC estimation of a storage battery, a current integration method of charge / discharge current is known. Moreover, the internal resistance of a storage battery changes with states, such as temperature and an electric current. When the internal resistance of the storage battery changes, the chargeable / dischargeable capacity also changes, so that an error occurs between the actually measured remaining capacity and the estimated SOC. For this reason, it is also known that the efficiency corresponding to the charge / discharge characteristics of the storage battery is calculated based on the current and temperature of the storage battery, and the remaining capacity is calculated in consideration of the capacity that can be discharged using the efficiency.

As disclosed in Patent Document 1 below, an apparatus and a method for estimating SOC using efficiency by a current integration method are disclosed.

JP2008-190995

Now, when the SOC is estimated using the efficiency in the current integration method, the current integration value is corrected so that the values match at 0% and 100% of the SOC. For this reason, the SOC estimation accuracy is good in the vicinity of 0% and 100% of the SOC, but the SOC estimation error increases as the SOC moves away from the vicinity of 0% and 100%, and the SOC estimation accuracy deteriorates.

Therefore, an object of the present invention is to improve the estimation accuracy not only in the vicinity of 0% and 100% of the SOC but also in the entire SOC range.

The SOC estimation apparatus detects the current and temperature of the storage battery, a table that defines the dependency between the efficiency of correcting the amount of electricity of the storage battery when fully charged, the temperature and the current, and the detection unit. The table is referred to based on the current and the temperature, and a table reference unit for acquiring the efficiency, and the charge amount corrected with the efficiency acquired by the table reference unit is set as the first target value, which is smaller than the first target value. The second target value, the third target value, and the fourth target value are set in order, and the first SOC, the second target value, and the fourth target value corresponding to the first to fourth target values are stopped. 2 SOC, 3rd SOC, 4th SOC in the state of the end of discharge, and from the first target value to the 4th target value from the charge amount and SOC obtained before time T1, The first SOC to the fourth SO A target value and a first calculation unit that calculates the SOC, and a difference amount between the target value obtained from the first calculation unit and the amount of charged electricity estimated before time T1 And a second calculation unit that calculates an integration coefficient from a ratio between the target SOC and a difference amount between the SOC estimated before time T1 and the integration coefficient calculated by the calculation unit and detected at time T1 An SOC estimation unit that obtains the SOC from the current integrated value obtained by adding the product of the current to the current integrated value before time T1.

The SOC estimation apparatus according to the present invention can reduce errors throughout the SOC estimation and improve the SOC estimation accuracy.

It is drawing explaining the structure of the SOC estimation apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the process for SOC estimation which concerns on Embodiment 1 of this invention. It is drawing which prescribed | regulated the relationship between the amount of electric charge and SOC which concern on Embodiment 1 of this invention. It is drawing which prescribed | regulated the relationship between the amount of charge electricity at the time of charge and SOC concerning Embodiment 1 of this invention. It is drawing which prescribed | regulated the relationship between the amount of charge electricity at the time of discharge and SOC concerning Embodiment 1 of this invention. It is drawing which showed the flowchart for demonstrating the process for SOC estimation which concerns on Embodiment 1 of this invention. It is drawing which prescribed | regulated the relationship between the amount of charge electricity at the time of charge and SOC concerning Embodiment 2 of this invention. It is drawing which prescribed | regulated the relationship between the amount of charge electricity at the time of discharge and SOC concerning Embodiment 2 of this invention.

An outline of the embodiment of the present invention will be described. The embodiment relates to a storage battery used in a power distribution system equipped with an industrial / residential storage battery, HEV (Hybrid Electric vehicle), or the like. Such a device is used, for example, in such a manner that power is discharged when a user wants to use it, and power is charged when he wants to charge. Therefore, it is considered that the SOC of the storage battery is not charged / discharged between 100% and 0%, and the SOC of the storage battery is repeatedly charged / discharged between 70% and 30%. Therefore, if the SOC is estimated using the efficiency in the current integration method, an error from the actual amount of electricity occurs in the middle region of the SOC where the SOC is between 70% and 30%. Therefore, regarding the storage battery used in the above-mentioned device, it is desired to eliminate the error in the amount of electricity in the intermediate region of the SOC of the storage battery.

FIG. 1 is a diagram for explaining a configuration of an SOC estimation apparatus 60 according to an embodiment of the present invention.

Storage battery unit 50 is connected to SOC estimation device 60 through

connection terminals

10 and 20. The connection terminal 10 is connected to the positive terminal of the storage battery unit 50, and the connection terminal 20 is connected to the negative terminal of the storage battery unit 50. The connection terminal 10 is connected to the output-side connection terminal 30 via the SOC estimation device 60, and the connection terminal 20 is connected to the output-side connection terminal 40 via the SOC estimation device 60. The electric power of the storage battery unit 50 is charged and discharged from the

connection terminals

30 and 40.

The storage battery unit 50 charges and discharges DC power supplied from the outside. When the supplied power is AC, the storage battery unit 50 is supplied with DC power converted by a bidirectional power conditioner (not shown) that converts AC power into DC power.

The storage battery unit 50 may be composed of at least one storage battery, but a storage battery unit 50 may be formed by connecting a plurality of storage batteries in series or in parallel. In addition, a storage battery should just be a secondary battery, for example, there exist a lithium ion battery, a nickel metal hydride battery, a lead acid battery, etc. When the storage battery unit 50 is composed of a plurality of storage batteries, the number of storage batteries is arbitrary and is determined by the designer.

The SOC estimation device 60 includes at least a control unit 80 and a detection unit 70. However, the SOC estimation device 60 may be configured to include the storage battery unit 50. The detection unit 70 detects at least the current and temperature of the storage battery unit 50. In the embodiment of the present invention, regarding the temperature detection, the method of detecting the temperature of the storage battery unit 50 from the current flowing through the storage battery unit 50 using a thermistor, and the current detection, the storage battery unit 50 is detected by a current detection resistor. A description will be given using a method of detecting a charged / discharged current, A / D converting the detected current via an A / D conversion terminal, and calculating a current by the control unit 80. Further, when the current is detected, the detection unit 70 determines that charging is performed if the current is a positive value, and discharging is performed if the current is a negative value. In addition to temperature and current, voltage or the like may be detected. The detection unit 70 may be any detection method as long as it can detect temperature and current.

The control unit 80 acquires the current and temperature values detected by the detection unit 70. The control unit 80 includes a communication terminal 90 that outputs data acquired from the detection unit 70 or data calculated in the control unit 80 to the outside. As data to be output to the outside, current, temperature, SOC calculated by the control unit 80, and the like can be considered.

Next, the SOC estimation process performed in the control unit 80 will be described. FIG. 2 is a block diagram showing processing for SOC estimation according to Embodiment 1 of the present invention.

The control unit 80 includes at least a table reference unit 81, a first calculation unit 82, a second calculation unit 83, and an SOC estimation unit 84.

The table reference unit 81 has a table that defines the dependency relationship between the efficiency of correcting the amount of electricity when the storage battery unit 50 is fully charged and the current and temperature of the storage battery unit 50. (Not shown) The table reference unit 81 refers to the table from the current and temperature values acquired at time T1, and acquires the efficiency.

In the following description, the table is described as one table, but the table includes a table of current and temperature when the storage battery unit 50 is charged, and charging efficiency for correcting the amount of electricity when the storage battery unit 50 is fully charged, and a storage battery. The unit 50 may be divided into a table of current and temperature when discharging, and discharge efficiency for correcting the amount of electricity when the storage battery unit 50 is fully charged.

The first calculation unit 82 calculates the SOC associated with the target point of charge electricity amount and the target point of charge electricity amount at the time of charging or discharging. Here, the amount of electricity charged is a percentage of the amount of electricity of the storage battery unit 50 obtained by dividing a full charge capacity (hereinafter referred to as FCC: Full Charge Capacity) by a value obtained by integrating the current flowing through the storage battery unit 50.

Since the charge electricity amount at the time of charging and discharging is the same calculation method, the following description will describe a calculation method for the charge electricity amount at the time of charging using efficiency. The first calculation unit 82 calculates a first charge electricity amount that is a charge electricity amount at which charging is terminated from the efficiency acquired by the table reference unit 81.

In the first method for calculating the amount of charged electricity, the efficiency acquired by the table reference unit 81 is multiplied by the current integrated value calculated immediately before time T1, and the percentage obtained by dividing the multiplied value by the FCC is obtained. it can. In addition, when there is no current integrated value calculated immediately before time T1, if the current detected by the detection unit 70 at time T1 is a positive value, the amount of charge to be in a predetermined discharge end state at time T1. If the current detected by the detection unit 70 is a negative value, the charge amount that is in a predetermined charge termination state may be set as the first charge amount. Or you may obtain | require charge electric energy from the table which prescribed | regulated the relationship between the value of open circuit voltage, and charge electricity by further providing the detection part 70 which can detect open circuit voltage.

Since the first calculation unit 82 defines the SOC when the amount of charge electricity is in the state of charge termination as 100%, when the first amount of charge electricity is obtained, the first charge amount corresponding to the first amount of charge electricity is calculated. The SOC can also be obtained. The first calculator 82 has a first table that defines the relationship between the amount of charge electricity and SOC during charging, and a second table that defines the relationship between the amount of charge electricity and SOC during discharge. Here, the first charge electric quantity and the first SOC are the coordinates when the electric charge is indicated by a coordinate on a plane (refer to FIG. 5) with the horizontal axis of the SOC and the vertical axis of the SOC. The target point. By obtaining the first target point, the second, third, and fourth target points can also be obtained by a calculation method defined in advance. Hereinafter, how to obtain the second, third, and fourth target points will be described.

The fourth target point calculation method can obtain the fourth charge electricity amount that is in the discharge end state by subtracting the first charge electricity amount from 100%. In addition, since the SOC corresponding to the fourth charge electricity amount is defined as 0%, a point that coordinates the fourth charge electricity amount and the fourth SOC is set as a fourth target point.

The second target point is calculated by subtracting a preset value X from the first charge electricity amount to obtain the second charge electricity amount. The second SOC corresponding to the second charge electricity amount is set to be the same value as the second charge electricity amount. Therefore, at the second target point, the second charge electricity amount and the second SOC are the same value, and a point having the second charge electricity amount and the second SOC as coordinates is set as the second target point.

The calculation method of the third target point is obtained by adding the preset value X used at the second target point to the fourth charge electricity amount. Further, the third SOC corresponding to the third target point of the charged electricity amount is set to be the same value as the third target point of the charged electricity amount. A point having the third charge electricity amount and the third SOC as coordinates is set as a third target point. Note that the preset value X is freely changed depending on the usage state of the storage battery, but it is desirable to set it so that an intermediate region of the SOC exists. Further, the preset value X may be set so that the value subtracted from the first charge electricity amount does not become less than 50%, or the value added from the third charge electricity amount does not become 50% or more. desirable.

The first to fourth charge electricity amounts and the first to fourth SOC obtained by the first calculation unit 82, the charge electricity amount and SOC obtained immediately before the time T1, the charge electricity amount and SOC at the time of charge, Based on a table that defines the relationship, a target point at the time T1 is determined from the first target point to the fourth target point. A method of determining the target point will be described in detail with reference to FIG.

FIG. 3 is a drawing of a first table that defines the relationship between the amount of charged electricity and SOC during charging according to the embodiment of the present invention.

In FIG. 3, the horizontal axis of the first table indicates the amount of charged electricity, and the vertical axis indicates the SOC. The first table is selected by determining whether charging or discharging is performed based on the positive and negative values of the current detected by the detection unit 70. In the first table, the amount of charged electricity and the SOC are each divided in a preset area, and a target point is set for each divided area.

Here, in the preset area, each of the charge amount and SOC is divided into three areas, and the first table is set to be divided into nine areas. The boundary lines of the regions for dividing into three regions are calculated based on the efficiency acquired from the table reference unit 81, the calculated second charging electricity amount and the third charging electricity amount, the second SOC, and the third SOC. Set by the SOC.

In the first table, target points are set in advance for each divided area. For example, 2 is displayed in the area 500, which indicates the number of the target point, and the target point in the area 500 is 2. A target point number is set for each of the divided areas, but the target point number may be set so as to reduce an error between the charge / discharge electricity amount and the SOC. For example, when the storage battery unit 50 is charged, the target point in the region 100 is a target point from 1 to 3, and the target point 3 closest to the region 100 among the candidates is set as the target point. In the

regions

200, 400, and 500, the target points 1 and 2 are candidate targets, and the target point 2 closest to the

regions

200, 400, and 500 is set as the target point. In the

regions

300, 600, 700, 800, and 900, the target candidate is only 1, and 1 is set as the target point.

The target point is set to 1 to 4 in a region to which a point having the coordinates of the charged electric energy and SOC obtained immediately before time T1 belongs. The drawing that defines the relationship between the amount of charged electricity and SOC during charging according to Embodiment 1 of the present invention shown in FIG. 4 also sets the target point with the same setting as in FIG.

The second calculation unit 83 is a coefficient for correcting the current integrated value at the time T1 from the target point calculated by the first calculation unit 82, the charge amount estimated immediately before the time T1, and the SOC value. Calculate the integration coefficient. The method for calculating the integration coefficient will be described in detail with reference to FIG.

FIG. 5 is a drawing that defines the relationship between the amount of charged electricity during discharging and the SOC according to the embodiment of the present invention. The relationship between the charge electricity amount and the SOC is based on the charge electricity amount and the SOC calculated by the first calculation unit 82.

5, the horizontal axis indicates the amount of charged electricity, and the vertical axis indicates the SOC. Points 1 to 4 shown in the figure indicate the coordinate relationship of the SOC corresponding to the target value of the charge electricity amount and the charge electricity amount in the first calculation unit 82. From the largest, they are the first target point, the second target point, the third target point, and the fourth target point.

The SOC estimation unit 84 acquires the current value detected at time T1. Moreover, the integrated current value calculated immediately before time T1 is stored.

The integration coefficient is obtained by subtracting the SOC corresponding to the target point from the SOC measured before time T1 and the difference amount when the charging electricity amount at the target point is subtracted from the charging electricity amount measured immediately before time T1. It is calculated | required from the ratio with the difference amount.

The SOC multiplies the current value acquired at time T1 by the integration coefficient calculated by the second calculation unit 83, and adds the current integration value immediately before time T1 to the multiplied value. The added value is divided by the FCC and can be obtained from the percentage of the divided value.

FIG. 6 is a flowchart showing a process of the control unit 80 for estimating the SOC according to the embodiment of the present invention.

The table reference unit 81 acquires the current and temperature detected by the detection unit 70 at time T1. Moreover, the table reference part 81 judges whether the storage battery part 50 is a charge state or a discharge state from the positive / negative value of the acquired electric current, and sends the charging / discharging information of the storage battery part 50 to a 1st calculation part. (S1)
The table reference unit 81 refers to the table based on the acquired current and temperature, and acquires the efficiency. (S2)
The first calculation unit 82 selects the first table or the second table based on the positive and negative values of the current acquired from the detection unit 70. Then, based on the efficiency acquired from the table reference unit 81, the first to fourth charge electricity amounts and the first to fourth SOC are calculated. Based on the selected table, the calculated first to fourth charge amounts and the first to fourth SOCs, the selected table is divided for each region, and a target point is set for each region. (S3)
The first to fourth targets corresponding to the first to fourth charge electricity amounts and the first to fourth SOCs based on the calculated first to fourth charge electricity amounts and the first to fourth SOCs. Calculate points. (S4)
The first calculation unit 82 determines a target point from the first to the fourth based on the corresponding positional relationship between the SOC and the SOC calculated one time before the time T1 in each divided table area. . (S5)
The second calculation unit 83 obtains the difference amount of the charge electricity amount and the difference amount of the SOC from the target point calculated by the first calculation unit 82 and the charge amount and SOC calculated immediately before the time T1. The integration coefficient is calculated from the difference amount ratio. (S6)
The SOC estimation unit 84 obtains a value obtained by multiplying the integration coefficient calculated by the second calculation unit 83 by the current detected at time T1. The value is added to the current integrated value obtained immediately before time T1, and the SOC at time T1 is obtained from the ratio of the added value and FCC. (S7)
The above processing is executed at a constant cycle, for example, at a cycle of 1 ms.

As described above, according to the SOC estimation apparatus 60 according to the embodiment as described above, the present invention can reduce the estimation error of the entire SOC and improve the SOC estimation accuracy.

Further, the second target point and the third target point are set by matching the values of the second target point and the second SOC and the values of the third target point and the third SOC. It is possible to reduce the estimation error in the region. Therefore, the SOC estimation accuracy is improved particularly in the middle region of the SOC.

In the first table that defines the relationship between the amount of charge electricity and SOC during charging according to the first embodiment shown in FIG. 3, the coordinates of the amount of charge electricity calculated before the time T1 and the SOC are the amount of charge electricity. In the case where the SOC value is larger than the range, the SOC estimation is continued without eliminating the error generated between the charged electric charge and the SOC. Further, in the second table that defines the relationship between the charged electric charge during discharging and the SOC according to the first embodiment shown in FIG. 4, the coordinates of the charged electric charge and SOC calculated immediately before time T1 are charged. Even when the SOC value is smaller than the amount of electricity, the SOC estimation is continued without eliminating the error between the charged amount of electricity and the SOC. Embodiment 2 of the present invention corresponding to the case where an error occurring between the amount of charged electricity and the SOC is included can be solved.

FIG. 7 is a drawing of a third table that defines the relationship between the amount of charged electricity and SOC during charging according to the second embodiment. FIG. 8 is a drawing of a fourth table that defines the relationship between the amount of charged electricity during discharging and the SOC according to the second embodiment.

7 and 8, the horizontal axis of the third table and the fourth table indicates the amount of charged electricity, and the vertical axis indicates the SOC. The third table shown in FIGS. 7 and 8 is the same setting as the first table, and the fourth table is the same as the second table, so the description is omitted. Here, when the third table is selected, and the positional relationship between the SOC and the SOC calculated just before time T1 belongs to a region where the SOC value is larger than the SOC, the target point is the time T1. A target value that is larger and closest to the amount of charged electricity calculated immediately before is selected. When the fourth table is selected and the positional relationship between the SOC and the SOC calculated just before time T1 belongs to a region where the SOC value is smaller than the SOC, the target point is one at time T1. A target value that is smaller and closest to the amount of charge electricity calculated previously is selected.

The setting of the target point for each area of the third table and the fourth table is set depending only on the amount of charged electricity. Therefore, the error can be quickly eliminated as compared with the first table and the second table.

The first calculation unit 82 has first to fourth tables, and the first table is changed to the third table or the second table is changed to the third table depending on the temperature and current values detected by the detection unit 70. You may enable it to change to the table of 4.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

For example, the first table and the second table described in the first embodiment of the present invention and the third table and the fourth table described in the second embodiment of the present invention are divided into nine setting areas. You may increase or decrease. If the target point is set to two and the setting area is divided into two areas for the charge electricity amount and the SOC area is divided into four areas, the charge electricity amount is 50% and the SOC is 50%, which are intermediate values. Corresponds by positional relationship. In addition, if the target point is set to four, and the setting area is divided into four charging electric charge areas and the SOC area into four 16 areas, the charging electric power is more than that in the case of dividing into nine setting areas. The error in the area where the amount and the SOC do not match can be reduced.

10, 20, 30, 40 connection terminal, 50 storage battery unit, 60 SOC estimation device, 70 detection unit, 80 control unit, 81 table reference unit, 82 first calculation unit, 83 third calculation unit, 84 SOC estimation unit , 90 communication terminals, 100, 200, 300, 400, 500, 600, 700, 800, 900 areas.

Claims

A detection unit for detecting the current and temperature of the storage battery;
A table that defines the efficiency of correcting the amount of electricity of the storage battery at full charge, and the dependence relationship between temperature and current;
Referring to the table based on the current and temperature detected by the detection unit, and a table reference unit for obtaining efficiency;
The amount of charged electricity corrected by the efficiency acquired by the table reference unit is set as the first target value, and the second target value, the third target value, and the fourth target value are set in order from the first target value. The first SOC, the second SOC, the third SOC, and the fourth SOC in the end of discharge state are set to correspond to the first to fourth target values. Set,
A target value and SOC are calculated from the first target value to the fourth target value and from the first SOC to the fourth SOC from the charged electricity amount and SOC obtained before time T1. A first calculation unit;
The amount of difference between the target value obtained as a target obtained from the first calculation unit and the amount of charged electricity estimated before time T1, and the amount of difference between the target SOC and the SOC estimated before time T1 A second calculation unit that calculates the integration coefficient from the ratio of:
An SOC estimation unit 84 for obtaining SOC from a current integrated value obtained by adding the product of the integration coefficient calculated by the calculation unit and the current detected at time T1 to the current integrated value before time T1,
An SOC estimation apparatus comprising:
The first calculation unit calculates a target value and an SOC that are targets according to a charge / discharge state of a storage battery from the first target value to the fourth target value and from the first SOC to the fourth SOC. A table for calculating,
The SOC estimation apparatus according to claim 1, wherein the storage battery calculates the target value and SOC as the target in consideration of a charge / discharge state from the table.
The integration coefficient is determined between the second target value and the third target value, with the integration coefficient determined between the first target value and the second target value as the first integration coefficient. The second integration coefficient is the second integration coefficient, the integration coefficient obtained between the third target value and the fourth target value is the third integration coefficient, and the second integration coefficient is the first integration coefficient. 3. The SOC estimation apparatus according to claim 1, wherein the SOC estimation device has a value smaller than an integration coefficient and the third integration coefficient.
4. The SOC estimation apparatus according to claim 3, wherein the value of the second integration coefficient is 1.