KR101546324B1 - Apparatus and Method for Predicting SoC of Secondary Battery - Google Patents

Abstract

The present invention relates to an apparatus and a method for predicting a state of charge (SOC) of a secondary battery. The apparatus of the present invention includes: an interpolation calculation part which calculates a state of charge by applying interpolation from a voltage-current characteristics graph; an integration calculation part which calculates the SOC by applying integration; an assembly computation processing part which performs assembly computation of the SOC value outputted from the interpolation calculation part and the SOC value outputted from the integration calculation part; an SOC judgment part which outputs the SOC value processed by assembly computation, and outputs a switching control signal at an established SOC value; and a switching part which is connected between the interpolation calculation part and the assembly computation processing part, and performs on/off switching in correspondence to the switching control signal. According to the present invention, the apparatus can prevent full discharge by alarming a charging restart time in case remaining power is within a zone 1 (0% ~ 20%), and can prevent over-charging and also can maintain full charging state by alarming a charging finish time in case the remaining power is within a zone 2 (80% ~ 100%).

Description

Technical Field [0001] The present invention relates to an apparatus and method for predicting a state of charge of a secondary battery,

The present invention relates to an apparatus and method for predicting a state of charge of a secondary battery, and more particularly, to an apparatus and method for predicting state of charge of a secondary battery, which improves measurement accuracy of a state of charge by applying different prediction techniques corresponding to a state of charge Apparatus and method.

A secondary battery (rechargeable battery) means a battery which is charged semi-permanently by using an external power source. Secondary batteries are mainly used in portable devices, and they are considered to be 'three major electronic components' in the 21st century along with semiconductors and displays due to their high added value. Examples of the secondary battery include a nickel battery, an ion battery, a lithium ion battery, a polymer battery, a lithium polymer battery, and a lithium sulfide battery, depending on the kind of the filling material.

One of the main tasks of such a secondary battery is to increase the use time and accurately predict the state of charge (SoC). For example, if the measurement accuracy of the charge state is 10%, the system uses only 90% of the charge state (battery level) to prevent significant data loss, and then notifies the system user of the secondary battery replacement time. This means a 10% capacity wastage, or a 10% drive time loss.

For example, in the case of a secondary lithium battery including a lithium ion battery, a lithium polymer battery, and a lithium sulfide battery, the state of charge (remaining battery power) is determined by the mechanical properties of the battery Voltage, current, temperature, resistance, etc., and deriving the correlation for each variable. The application of the open circuit voltage (OCV) of the battery in a relatively simple manner and the application of the interpolation method from the voltage-current characteristic graph are examples. However, this method has a disadvantage in that an error increases with respect to dynamic variation. As another method, as an integration method, there is a method of integrating the current with respect to the measurement time interval. However, this method is relatively accurate in estimating the dynamic change, but has a disadvantage of accumulating errors.

On the other hand, the remaining amount of the battery requires a higher precision in a specific region among the entire region (0% to 100%). That is, in region 1 (0% to 20%), it is necessary to accurately calculate the end-of-use point to predict the time point of recharging. In Region 2 (80% to 100%), it is necessary to accurately predict the end of charge in order to prevent overcharge.

Korean Patent Publication No. 10-2005-0065553 (Published Jun. 27, 2005) Korean Patent Publication No. 10-2007-0060215 (Published Jun. 23, 2007) Korean Registered Patent No. 10-1097956 (Published on December 22, 2011)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems of the prior art, and it is an object of the present invention to provide a battery, which is obtained by internal interpolation and integration using a battery capacity and a current- The present invention provides an apparatus and method for predicting the state of charge of a secondary battery that improves the measurement accuracy of a battery remaining amount through a combination calculation process of residual amounts.

According to an aspect of the present invention, there is provided an apparatus for predicting a state of charge of a secondary battery, the apparatus including: an internal interpolation method calculator for calculating a state of charge by applying interpolation from a voltage-current characteristic graph; An integration method calculation unit for calculating a charge state by applying an integration method; A combination operation processing unit for performing a combination operation process on the charge state value output from the internal interpolation method calculation unit and the charge state value output from the integration method calculation unit; A charge state determiner for outputting a charge state value after the combination operation and outputting a switching control signal at a set charge state value; And a switching unit connected between the internal interpolation method calculating unit and the combining operation processing unit and performing on / off switching according to the switching control signal.

In another aspect of the present invention, there is provided a secondary battery charging state predicting method including: acquiring secondary battery information including voltage, current, and temperature; Calculating a state of charge by applying an interpolation method from the voltage-current characteristic graph, and calculating a state of charge by applying integration from the secondary battery information; Calculating a charge state value calculated by the internal interpolation method and a charge state value calculated by an integration method at a predetermined ratio; And outputting a charge state value output by the combination operation processing.

를 이용하여 계산되는 것이 바람직하다.At this time, the combination operation processing

As shown in FIG.

Here, "y" is the corrected charge state value, "y1" is the charge state value calculated by the internal interpolation method from the voltage-current characteristic graph, "y2" is the charge state value calculated by the integration method, "m" Current / battery capacity).

On the other hand, when the charge state value output by the combination operation processing is 0% to 20%, or 80% to 100%, it is preferable to calculate the charge state value by applying only the integration method.

As described above, according to the apparatus and method for predicting the state of charge of the secondary battery according to the present invention, when the remaining battery level is in the region 1 (0% to 20%), the full-discharge can be prevented by alerting the charging resume point.

Further, according to the present invention, when the battery remaining amount is in the region 2 (80% to 100%), overcharge is prevented by alerting the charging end point, and the maximum buffering state can be maintained.

1 is a block diagram of a control circuit of a secondary battery charging state predicting apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart of a method of predicting a state of charge of a secondary battery according to an embodiment of the present invention.
FIG. 3 is a graph comparing SOC changes during discharge of a lithium secondary battery having a rated capacity of 20 Ah.
FIG. 4 is a graph comparing SOC changes during discharge of a lithium secondary battery having a rated capacity of 20 Ah.
5 is a graph comparing the SOC changes of a lithium secondary battery having a rated capacity of 20 Ah during 10 A discharging.

Hereinafter, an apparatus and method for predicting the state of charge of a secondary battery according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a control circuit of a secondary battery charging state predicting apparatus according to an embodiment of the present invention.

Referring to FIG. 1, an apparatus for predicting the state of charge of a secondary battery according to the present invention includes an internal interpolation method calculation unit 1 for calculating a charging state by applying an interpolation from a voltage-current characteristic graph, A charge state value output from the internal interpolation method calculation unit 1 and a charge state value output from the accumulation method calculation unit 2, A charge state judging section 4 for outputting a charge state value subjected to a combination operation process and outputting a switching control signal at a set charge state value and an internal interpolation method calculating section 1 and a combination operation processing section 3 ) For switching on / off in response to the switching control signal.

The apparatus for predicting the state of charge of a secondary battery configured as described above calculates a state of charge by applying an internal interpolation method in the internal interpolation method calculation unit 1 and applies an integration method in the integration method calculation unit 2 Calculate the state of charge. The combination operation processing unit 3 then performs a combination operation process using the battery capacity and current correction factors for the charge state value output from the internal interpolation method calculation unit 1 and the charge state value output from the integration method calculation unit 2 And outputs the charge state value subjected to the combination operation processing. Subsequently, when the charge state determining unit 4 outputs the charge state value that has undergone the combination operation processing and the charge state value that has undergone the combination operation processing is out of the setting range (21 to 79%), that is, And outputs a switching control signal when the value is the area 1 (0% to 20%) or the area 2 (80% to 100%). In response to the switching control signal, the switching unit 5 outputs the charge state value output from the internal interpolation method calculation unit 1 as "0 ". That is, when the charge state value subjected to the combination operation process is the region 1 (0% to 20%) or the region 2 (80% to 100%), only the charge state value output from the integration method calculation section 2 is output, So that accurate prediction can be made for the corresponding dynamic variation.

A description will now be made of a secondary battery charging state predicting method using the secondary battery charging state predicting apparatus configured as described above.

FIG. 2 is a flowchart of a method of predicting a state of charge of a secondary battery according to an embodiment of the present invention.

Referring to FIG. 2, first, secondary battery information including voltage, current, temperature, and the like is acquired to calculate a charged state (remaining battery level) (S1).

The charging state is calculated by applying an interpolation from the voltage-current characteristic graph from the secondary battery information, and the charging state is calculated by applying the integration from the secondary battery information (S2).

The charge state value calculated by the internal interpolation method and the charge state value calculated by the integration method calculation unit 2 are subjected to a combination calculation process using the following formula (S3).

[expression]

"Y1" is the charge state value calculated by the internal interpolation method from the voltage-current characteristic graph, "y2" is the charge state value calculated by the integration method, "m" is the correction factor (= Current / battery capacity).

At this time, it is judged whether or not the charge state value in the combination calculation process is within the set range (21 to 79%) (S4). If the charge state value exists within the set range, the output of the charge state value outputted by the above- (S5).

As described above, it is possible to improve the measurement accuracy of the charged state by proportionally applying the interpolation method and the integration method corresponding to the charged state (remaining battery level).

(0% to 20%) or the region 2 (80% to 100%) is not present within the set range (21 to 79%), (S6), only the integration method is applied so that the dynamic variation corresponding to the battery remaining amount can be accurately predicted. This process is repeated until the charge state value of the combination operation process is returned to the original setting range (S7).

Table 1 shows SOC value (y1) calculated by interpolation method, SOC value (y2) calculated by the integration method while discharging lithium secondary battery to 2A, SOC value (y) (measured). The lithium-ion battery used here was manufactured by connecting 10 pieces of single cells having an average voltage of 3.6 V and a capacity of 3.33AH in series, and connecting them in parallel to each other to obtain an average voltage of 36 V and a rated capacity of 20 Ah. FIG. 3 is a graph comparing SOC changes during discharge of a lithium secondary battery having a rated capacity of 20 Ah.

Table 2 shows SOC value (y1) calculated by interpolation method, SOC value (y2) calculated by integrating method while discharge at 6A using the same battery as in Table 1, correction SOC value (y) proposed by the present invention, And the measured SOC values (measured) in the experiment. FIG. 4 is a graph comparing SOC changes during discharge of a lithium secondary battery having a rated capacity of 20 Ah.

Table 3 shows the SOC value y1 calculated by the interpolation method, the SOC value y2 calculated by the integration method, the corrected SOC value y suggested by the present invention, And the measured SOC values (measured) in the experiment. 5 is a graph comparing the SOC changes of a lithium secondary battery having a rated capacity of 20 Ah during 10 A discharging.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

1: internal interpolation method calculation unit
2:
3: Combination operation processing unit
4: charge state judging unit
5:

Claims (4)

An internal interpolation method calculation unit for calculating a charging state by applying interpolation from a voltage-current characteristic graph;
An integration method calculation unit for calculating a charge state by applying an integration method;
A combination operation processing unit for performing a combination operation process on the charge state value output from the internal interpolation method calculation unit and the charge state value output from the integration method calculation unit;
A charge state determiner for outputting a charge state value after the combination operation and outputting a switching control signal at a set charge state value; And
And a switching unit connected between the internal interpolation method calculation unit and the combination operation processing unit to perform on / off switching in response to the switching control signal,
Wherein the combination calculation processing is calculated using the following equation.

--- (expression)
Here, "y" is the corrected charge state value, "y1" is the charge state value calculated by the internal interpolation method from the voltage-current characteristic graph, "y2" is the charge state value calculated by the integration method, "m" Current / battery capacity).
Obtaining secondary battery information including voltage, current, and temperature;
Calculating charge state by applying interpolation from the voltage-current characteristic graph and calculating charge state by applying integration from the secondary battery information;
Calculating a charge state value calculated by the internal interpolation method and a charge state value calculated by an integration method at a predetermined ratio; And
And outputting a charge state value output by the combination operation processing,
Wherein the combined operation processing is calculated using the following equation.

--- (expression)
Here, "y" is the corrected charge state value, "y1" is the charge state value calculated by the internal interpolation method from the voltage-current characteristic graph, "y2" is the charge state value calculated by the integration method, "m" Current / battery capacity).
delete 3. The method of claim 2,
Wherein the charge state value is calculated by applying only the integration when the charge state value output by the combination operation processing is 0% to 20% or 80% to 100%.

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